ArticleLiterature Review

The future of antibodies as cancer drugs

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Abstract

Targeted therapeutics such as monoclonal antibodies (mAbs) have proven successful as cancer drugs. To profile products that could be marketed in the future, we examined the current commercial clinical pipeline of mAb candidates for cancer. Our analysis revealed trends toward development of a variety of noncanonical mAbs, including antibody-drug conjugates (ADCs), bispecific antibodies, engineered antibodies and antibody fragments and/or domains. We found substantial diversity in the antibody sequence source, isotype, carbohydrate residues, targets and mechanisms of action (MOA). Although well-validated targets, such as epidermal growth factor receptor (EGFR) and CD20, continue to provide opportunities for companies, we found notable trends toward targeting less-well-validated antigens and exploration of innovative MOA such as the generation of anticancer immune responses or recruitment of cytotoxic T cells.

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... Epidermal growth factor receptor (EGFR) is an important target for cancer therapeutic agents because it is expressed in many types of solid tumor and its expression level is correlated with malignancy, metastatic phenotype, and poor prognosis [12][13][14]. Two anti-EGFR therapeutic antibodies, cetuximab and panitumumab, are currently approved by the US Food and Drug Administration, and other anti-EGFR therapeutic antibodies are undergoing clinical trials [15]. Panitumumab is characterized by its high affinity to EGFR and is thought to function primarily through the blocking of ligand-receptor interactions. ...
... Panitumumab is characterized by its high affinity to EGFR and is thought to function primarily through the blocking of ligand-receptor interactions. It also has a decreased likelihood of damaging normal EGFR-positive cells because it belongs to the IgG2 subclass and therefore has reduced effector functions compared with cetuximab, which belongs to the IgG1 subclass [15,16]. ...
... There have also been reports of the induction of strong agonist activities by converting to the scFv diabody from the parental IgG [10,11]. Among the two currently approved therapeutic anti-EGFR antibodies, panitumumab is characterized by its high affinity, and it does not induce natural killer cell-mediated antibody-dependent cellular cytotoxicity like cetuximab does [15,16]. We previously constructed anti-EGFR scFv multimers that inhibited cancer cell growth in a multimerizationdependent manner [17]. ...
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The development of single-chain variable fragments (scFvs) as therapeutic agents has the potential to reduce the high cost of antibody production, but the development process often impairs scFv functions such as binding affinity and pharmacokinetics. Multimerization is one strategy for recovering or enhancing these lost functions. Previously, we constructed several antiepidermal growth factor receptor (EGFR) scFv multimers by modifying linker length and domain order. Antitumor effects comparable with those of the currently approved anti-EGFR therapeutic antibodies were observed for scFv trimers. In the present study, we fractionated an anti-EGFR scFv tetramer from the intracellular soluble fraction of an Escherichia coli transformant. Compared with the trimer, the tetramer showed higher affinity, greater cancer cell growth inhibition, and prolonged blood retention time. Furthermore, the tetramer did not dissociate into the trimer or other smaller species during long-term storage (up to 33 weeks). Thus, our developed scFv tetramer is an attractive candidate next-generation anti-EGFR therapeutic antibody that can be produced via a low-cost bacterial expression system.
... Monoclonal antibody (mAb) technology is an excellent tool for the identification of novel and overexpressed cell surface antigens in human malignancies and mAb-based products have untapped therapeutic and diagnostic potential in cancer. Indeed, the exquisite specificity of mAbs for their target antigens makes them an attractive approach for targeted cancer therapy [9][10][11][12][13][14]. To date, 32 mAbs have been approved for cancer treatment in the U.S. and/or European Union. ...
... There is an urgent need to discover novel biomarkers of diagnostic, prognostic and predictive values and therapeutic targets in patients with pancreatic cancer. As mAb-based products are highly specific for their target antigens, they have been routinely used as diagnostic and therapeutic agents in many pathological conditions including cancer [9][10][11][12][17][18]. Moreover, mAb technology is an excellent tool for the discovery of novel overexpressed cell surface tumour antigens and the study of their functions. ...
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Pancreatic cancer is one of the most aggressive and lethal types of cancer, and more effective therapeutic agents are urgently needed. Overexpressed cell surface antigens are ideal targets for therapy with monoclonal antibody (mAb)-based drugs, but none have been approved for the treatment of pancreatic cancer. Here, we report development of two novel mouse mAbs, KU42.33C and KU43.13A, against the human pancreatic cancer cell line BxPC-3. Using ELISA, flow cytometry, competitive assay and immunoprecipitation followed by mass spectrometry, we discovered that these two mAbs target two distinct epitopes on the external domain of CD109 that are overexpressed by varying amounts in human pancreatic cancer cell lines. Treatment with these two naked antibodies alone did not affect tumour cell growth or migration in vitro. Of the two mAbs, only KU42.33C was useful in determining the expression of CD109 in tumour cells by Western blot and immunohistochemistry. Interestingly, immunohistochemistry of human pancreatic carcinoma tissue arrays with mAb KU42.33C showed that 94% of the 65 human pancreatic adenocarcinoma cases were CD109 positive, with no expression in normal pancreatic tissues. Our results suggest that these two novel mAbs are excellent tools for determining the expression level of CD109 in the tumour specimens and sera of patients with a wide range of cancers, in particular pancreatic cancer, and for investigating its diagnostic, prognostic and predictive value. Further research is warranted and should aim to unravel the therapeutic potential of the humanised forms or conjugated versions of such antibodies in patients whose tumours overexpress CD109 antigen.
... Some potential advances in antibody-related therapies also include the use of antibody-drug conjugates, bispecific antibodies, engineered antibodies, and antibody fragments (Reichert and Dhimolea 2012). The most advanced is the use of antibody-drug conjugates, which are already considered to be one of the most important subclasses of monoclonal antibodies (Peters and Brown 2015;Reichert and Dhimolea 2012). ...
... Some potential advances in antibody-related therapies also include the use of antibody-drug conjugates, bispecific antibodies, engineered antibodies, and antibody fragments (Reichert and Dhimolea 2012). The most advanced is the use of antibody-drug conjugates, which are already considered to be one of the most important subclasses of monoclonal antibodies (Peters and Brown 2015;Reichert and Dhimolea 2012). Although there is much progress yet to be made in these therapies, the literature recognizes room for improvement principally in immunogenicity, antigen-binding affinity, effector functions, and pharmacokinetics (Liu 2014). ...
Article
The aim of this paper is to generate qualified information on technologies that are expected to be relevant to cancer care over the next thirty years (2017–2037). Drawing on the concepts of technology foresight, a methodology was developed for future technology research. Future technologies were identified by consulting editorials of journals specializing in oncology. Nine technologies were selected with the potential to impact cancer care in the future. Additionally, a method was developed for consulting a large number of experts from articles indexed in Thomson Reuters Web of Science. In this survey, more than 83,000 cancer specialists were invited to answer a web survey in which they expressed their expectations about the future of cancer care. The questionnaire was answered by 2408 specialists, 56% of whom stated they were highly knowledgeable experts. Our results show that antibody-related therapies, molecular imaging, and tumor delivery systems are the technologies most likely to be used in cancer care in the next thirty years. The main reasons pointed out for the choice of these technologies were improvements in the prognosis of the disease and improved diagnostic reliability. Meanwhile, knowledge and scientific barriers were highlighted as the main obstacles to the development of the technologies deemed to have more limited chances of success.
... However, these molecules only provide short-term survival improvement [6] and more effective treatments to address chemo-resistant recurrent OC are not available yet. MAbs against surface antigens that are effective in different cancer types [7,8] display no or extremely moderate activities when tested in OCs. Nevertheless, a few innovative targets, among which folate receptor [9] or angiopoietins [10], are currently evaluated. ...
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Ovarian cancer is the leading cause of death in women with gynecological cancers and despite recent advances, new and more efficient therapies are crucially needed. Müllerian Inhibiting Substance type II Receptor (MISRII, also named AMHRII) is expressed in most ovarian cancer subtypes and is a novel potential target for ovarian cancer immunotherapy. We previously developed and tested 12G4, the first murine monoclonal antibody (MAb) against human MISRII. Here, we report the humanization, affinity maturation and glyco-engineering steps of 12G4 to generate the Fc-optimized 3C23K MAb, and the evaluation of its in vivo anti-tumor activity. The epitopes of 3C23K and 12G4 were strictly identical and 3C23K affinity for MISRII was enhanced by a factor of about 14 (KD = 5.5 × 10-11 M vs 7.9 × 10-10 M), while the use of the EMABling® platform allowed the production of a low-fucosylated 3C23K antibody with a 30-fold KD improvement of its affinity to FcγRIIIa. In COV434-MISRII tumor-bearing mice, 3C23K reduced tumor growth more efficiently than 12G4 and its combination with carboplatin was more efficient than each monotherapy with a mean tumor size of 500, 1100 and 100 mm3 at the end of treatment with 3C23K (10 mg/kg, Q3-4D12), carboplatin (60 mg/kg, Q7D4) and 3C23K+carboplatin, respectively. Conversely, 3C23K-FcKO, a 3C23K form without affinity for the FcγRIIIa receptor, did not display any anti-tumor effect in vivo. These results strongly suggested that 3C23K mechanisms of action are mainly Fc-related. In vitro, antibody-dependent cytotoxicity (ADCC) and antibody-dependent cell phagocytosis (ADCP) were induced by 3C23K, as demonstrated with human effector cells. Using human NK cells, 50% of the maximal lysis was obtained with a 46-fold lower concentration of low-fucosylated 3C23K (2.9 ng/ml) than of 3C23K expressed in CHO cells (133.35 ng/ml). As 3C23K induced strong ADCC with human PBMC but almost none with murine PBMC, antibody-dependent cell phagocytosis (ADCP) was then investigated. 3C23K-dependent (100 ng/ml) ADCP was more active with murine than human macrophages (only 10% of living target cells vs. about 25%). These in vitro results suggest that the reduced ADCC with murine effectors could be partially balanced by ADCP activity in in vivo experiments. Taken together, these preclinical data indicate that 3C23K is a new promising therapeutic candidate for ovarian cancer immunotherapy and justify its recent introduction in a phase I clinical trial.
... [1][2] This success has evolved into new generations of products, such as bispecific mAbs, mAb fragments, antibody-drug conjugates, and other derivatives. [3][4] However, because of their large size and the high degree of heterogeneity that may arise from various post-translational and chemical modifications during cell culture, purification, formulation, and storage, the characterization of these proteins continue to present a substantial challenge. [5][6][7] In an effort to support and promote high-quality measurements, the National Institute of Standards and Technology (NIST) issued a humanized IgG1k mAb reference material, RM 8671 (NIST-mAb). ...
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We describe the creation of a mass spectral library composed of all identifiable spectra derived from the tryptic digest of the NISTmAb IgG1κ. The library is a unique reference spectral collection developed from over six million peptide-spectrum matches acquired by liquid chromatography-mass spectrometry (LC-MS) over a wide range of collision energy. Conventional one-dimensional (1D) LC-MS was used for various digestion conditions and 20- and 24-fraction two-dimensional (2D) LC-MS studies permitted in-depth analyses of single digests. Computer methods were developed for automated analysis of LC-MS isotopic clusters to determine the attributes for all ions detected in the 1D and 2D studies. The library contains a selection of over 12,600 high-quality tandem spectra of more than 3,300 peptide ions identified and validated by accurate mass, differential elution pattern, and expected peptide classes in peptide map experiments. These include a variety of biologically modified peptide spectra involving glycosylated, oxidized, deamidated, glycated, and N/C-terminal modified peptides, as well as artifacts. A complete glycation profile was obtained for the NISTmAb with spectra for 63% and 100% of all possible glycation sites in the heavy and light chains, respectively. The site-specific quantification of methionine oxidation in the protein is described. The utility of this reference library is demonstrated by the analysis of a commercial monoclonal antibody (adalimumab, Humira®), where 691 peptide ion spectra are identifiable in the constant regions, accounting for 60% coverage for both heavy and light chains. The NIST reference library platform may be used as a tool for facile identification of the primary sequence and post-translational modifications, as well as the recognition of LC-MS method-induced artifacts for human and recombinant IgG antibodies. Its development also provides a general method for creating comprehensive peptide libraries of individual proteins.
... The biological activity of therapeutic IgGs is determined by two independent mechanisms: antigen recognition and Fc-mediated antibody effector functions, i.e., antibody-dependent cell-mediated cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC). [1][2][3][4][5][6][7] The N-glycans attached to the constant region (Fc) of an antibody have been demonstrated to be important for interaction of antibody with FcgRs and complement activation. The Fc-incorporated sugar is generally of the biantennary complex type, and consists of heptasaccharide comprising four N-Acetyl-Glucosamine (GlcNAc) and three mannose (Man) residues, and can be further varied by addition of galactose (Gal) and fucose (Fuc) residues as well as sialic acid (Sia, or N-acetylneuraminic acid, NANA, in human or N-glycolylneuraminic acid, NGNA, in mouse). ...
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Novel biotherapeutic glycoproteins, like recombinant monoclonal antibodies (mAbs) are widely used for the treatment of numerous diseases. The N-glycans attached to the constant region of an antibody have been demonstrated to be crucial for the biological efficacy. Even minor modifications of the N-glycan structure can dictate the potency of IgG effector functions such as the antibody-dependent cell-mediated cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC). Here, we present the development of a glycoengineered CHO-K1 host cell line (HCL), stably expressing β1,4-N-Acetylglucoseaminyltransferase III (GnT-III) and α-mannosidase II (Man-II), for the expression of a-fucosylated antibodies with enhanced Fc-mediated effector function. Glycoengineered HCLs were generated in a two-step strategy, starting with generating parental HCLs by stable transfection of CHO-K1 cells with GnT-III and Man-II. In a second step, parental HCLs were stably transfected a second time with these two transgenes to increase their copy number in the genetic background. Generated glycoengineered CHO-K1 cell lines expressing two different mAbs deliver antibody products with a content of more than 60% a-fucosylated glycans. In-depth analysis of the N-glycan structure revealed that the majority of the Fc-attached glycans of the obtained mAbs were of complex bisected type. Furthermore, we showed the efficient use of FcγRIIIa affinity chromatography as a novel method for the fast assessment of the mAbs a-fucosylation level. By testing different cultivation conditions for the pre-glycoengineered recombinant CHO-K1 clones, we identified key components essential for the production of a-fucosylated mAbs. The prevalent effect could be attributed to the trace element manganese, which leads to a strong increase of a-fucosylated complex- and hybrid-type glycans. In conclusion, the novel pre-glycoengineered CHO-K1 HCL can be used for the production of antibodies with high ratios of a-fucosylated Fc-attached N-glycans. Application of our newly developed FcγRIIIa affinity chromatography method during cell line development and use of optimized cultivation conditions can ultimately support the efficient development of a-fucosylated mAbs.
... The contributions of immune mechanisms to the antitumor effect of cetuximab and panitumumab are not yet fully defined. But immune mechanisms are unlikely to play a primary role here since it has been shown that panitumumab does not exhibit NKmediated antibody-dependent cytotoxicity, that not being the case for cetuximab, while both antibodies induce similar antitumor effects [184,187]. The predominant role of the mechanism of blockage of ligandreceptor interaction of anti-EGFR antibodies allows employing antibody fragments targeting this receptor for antitumor therapy. ...
Article
Monoclonal antibodies (mAbs) are an important class of therapeutic agents approved for the therapy of many types of malignancies. However, in certain cases applications of conventional mAbs have several limitations in anticancer immunotherapy. These limitations include insufficient efficacy and adverse effects. The antigen-binding fragments of antibodies have a considerable potential to overcome the disadvantages of conventional mAbs, such as poor penetration into solid tumors and Fc-mediated bystander activation of the immune system. Fragments of antibodies retain antigen specificity and part of functional properties of conventional mAbs and at the same time have much better penetration into the tumors and a greatly reduced level of adverse effects. Recent advantages in antibody engineering allowed to produce different types of antibody fragments with improved structure and properties for efficient elimination of tumor cells. These molecules opened up new perspectives for anticancer therapy. Here we will overview the structural features of the various types of antibody fragments and their applications for anticancer therapy as separate molecules and as part of complex conjugates or structures. Mechanisms of antitumor action of antibody fragments as well as their advantages and disadvantages for clinical application will be discussed in this review.
... Interestingly, splenic enlargement has been recently observed at magnetic resonance imaging (MRI) in 92% of the patients treated with T-DM1 for metastatic breast cancer [78] ( Figure 2D). Under these premises, the issue of splenic distribution of ADCs and of its possible impact on splenic function will certainly deserve further attention with the larger use in therapy of these drugs [79]. ...
Article
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After being absorbed, drugs distribute in the body in part to reach target tissues, in part to be disposed in tissues where they do not exert clinically-relevant effects. Therapeutically-relevant effects are usually terminated by drug metabolism and/or elimination. The role that has been traditionally ascribed to the spleen in these fundamental pharmacokinetic processes was definitely marginal. However, due to its high blood flow and to the characteristics of its microcirculation, this organ would be expected to be significantly exposed to large, new generation drugs that can hardly penetrate in other tissues with tight endothelial barriers. In the present review, we examine the involvement of the spleen in the disposition of monoclonal antibodies, nanoparticles and exosomes and the possible implications for their therapeutic efficacy and toxicity. The data that we will review lead to the conclusion that a new role is emerging for the spleen in the pharmacokinetics of new generation drugs, hence suggesting that this small, neglected organ will certainly deserve stronger attention by pharmacologists in the future.
... With the advent of genetic and protein engineering, modern medicine has reached a new era whereby protein therapeutics are playing an increasingly diverse and central role. One group in particular, monoclonal antibodies, make up the majority of these recombinant biotherapeutics currently in the clinical pipeline and are still one of the fastest growing classes of biologics to date (Reichert and Dhimolea, 2012). ...
... As shown in Figure 4d,e, the as-prepared nanodots showed a size of around 100 nm and were first taken up by cells, then escaped from the endosome owing to the proton sponge effect, and finally entered the ER, which can be exploited to track the vesicular transportation [67]. To evaluate the potential of nanoparticles as a visualization agent, researchers compared the photostability of nanodots and the commercial ER tracker under continuous light exposure for 15 min in MCF-7 cells The levels of IgM and IgG can serve as important indicators for infection in the early stage, and the detection of IgM/IgG is considered as an admirable and alternative method to diagnose COVID-19 [77,78]. Recently, a lateral flow immunoassay mediated by an NIR AIEgen-antigen probe for early detection of IgM/IgG was reported by Chen and coworkers [72]. ...
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Near-infrared (NIR) fluorescence materials have exhibited formidable power in the field of biomedicine, benefiting from their merits of low autofluorescence background, reduced photon scattering, and deeper penetration depth. Fluorophores possessing planar conformation may confront the shortcomings of aggregation-caused quenching effects at the aggregate level. Fortunately, the concept of aggregation-induced emission (AIE) thoroughly reverses this dilemma. AIE bioconjugates referring to the combination of luminogens showing an AIE nature with biomolecules possessing specific functionalities are generated via the covalent conjugation between AIEgens and functional biological species, covering carbohydrates, peptides, proteins, DNA, and so on. This perfect integration breeds unique superiorities containing high brightness, good water solubility, versatile functionalities, and prominent biosafety. In this review, we summarize the recent progresses of NIR-emissive AIE bioconjugates focusing on their design principles and biomedical applications. Furthermore, a brief prospect of the challenges and opportunities of AIE bioconjugates for a wide range of biomedical applications is presented.
... In addition, bispecific antibodies have made rapid inroad in cancer therapy. Together with bispecific antibodies, antibody-drug conjugates constitute the current trend for cancer treatment (37,38). The development of antibody and peptide conjugates will offer a novel design of targeted therapeutic drug delivery systems that have specificity and potent therapeutic efficacy. ...
Article
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PurposeLyP-1, a nine-amino-acid tumor homing peptide, selectively binds to its cognate receptor, p32. Overexpression of p32 in certain tumors should allow use of LyP-1 as a targeting agent for the delivery of therapeutic or diagnostic agents. Peptide conjugates are developed for enhanced pre-targeting of MDA-MB-231 breast cancer cells with peptide-antibody bispecific complexes and targeting with multiple-drug/-fluorophore-conjugated nano-polymers. Methods LyP-1-anti-DTPA bispecific antibody complexes (LyP-1-bsAbCx) were generated by conjugation of anti-DTPA antibody and LyP-1. LyP-1–doxorubicin (Dox), Dox-DTPA-succinyl-polylysine (Dox-DSPL), Dox-DSPL-LyP-1, DTPA-Dox-poly glutamic acid (D-Dox-PGA) or DTPA-rhodamine conjugated polylysine (DSPL-RITC) were prepared. In vitro therapeutic efficacy and targeting by immunofluorescence in MDA-MB-231 breast cancer cells were assessed with Dox-LyP-1. Immunofluorescence visualization of cancer cells was evaluated after pretargeting with LyP-1-bsAbCx and targeting with DSPL-RITC. ResultsCytotoxicity of Dox-LyP-1 conjugates was significantly greater than free doxorubicin (p < 0.0001). For fluorescent-labeled LyP-1, internalization occurred in 30 min in tumor cells. Fluorescence intensity of two-step targeted cells showed that pretargeting with LyP-1-bsAbC, followed by targeting with DSPL-RITC was greater than non-pretargeted DSPL-RITC (p < 0.05). Conclusions Peptide-conjugates are effective targeting agents for MDA-MB-231 breast cancer cells in culture. LyP-1-bsAbCx and Dox-LyP-1 conjugates may allow development of novel targeted cancer therapy and diagnosis.
... Antibodies targeting surface antigens have been demonstrated to be effective against different cancer types [21,22]. While some of these agents target tumor driver pathways (e.g. ...
... Different strategies have been used in the development of cancer therapeutic monoclonal antibodies (mAbs) including direct and immune-mediated cell killing, and targeting of the tumor neovasculature [2]. To improve clinical efficacy and to overcome some limitations of first generation mAb-based therapeutics, the industry is currently shifting towards innovative and more powerful modalities such as bi-specific antibodies and antibody-drug conjugates (ADCs) [3,4]. Antibody-drug conjugates offer the ability to deliver potent cytotoxic drugs specifically to tumor cells [5]. ...
Article
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The selection of therapeutic targets is a critical aspect of antibody-drug conjugate research and development. In this study, we applied computational methods to select candidate targets overexpressed in three major breast cancer subtypes as compared with a range of vital organs and tissues. Microarray data corresponding to over 8,000 tissue samples were collected from the public domain. Breast cancer samples were classified into molecular subtypes using an iterative ensemble approach combining six classification algorithms and three feature selection techniques, including a novel kernel density-based method. This feature selection method was used in conjunction with differential expression and subcellular localization information to assemble a primary list of targets. A total of 50 cell membrane targets were identified, including one target for which an antibody-drug conjugate is in clinical use, and six targets for which antibody-drug conjugates are in clinical trials for the treatment of breast cancer and other solid tumors. In addition, 50 extracellular proteins were identified as potential targets for non-internalizing strategies and alternative modalities. Candidate targets linked with the epithelial-to-mesenchymal transition were identified by analyzing differential gene expression in epithelial and mesenchymal tumor-derived cell lines. Overall, these results show that mining human gene expression data has the power to select and prioritize breast cancer antibody-drug conjugate targets, and the potential to lead to new and more effective cancer therapeutics.
... Therefore, such antibodies can be used for therapeutic development. Thus, more and more fully human antibodies obtained from antibody libraries are entering clinical development and are reaching the market (8). ...
Article
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We have developed the CD44v6-targeting human bivalent antibody fragment AbD19384, an engineered recombinant human bivalent Fab antibody formed via dimerization of dHLX (synthetic double helix loop helix motif) domains, for potential use in antibody-based molecular imaging of squamous cell carcinoma in the head and neck region. This is a unique construct that has, to the best of our knowledge, never been assessed for molecular imaging in vivo before. The objective of the present study was to evaluate for the first time the in vitro and in vivo binding properties of radio-iodinated AbD19384, and to assess its utility as a targeting agent for molecular imaging of CD44v6-expressing tumors. Antigen specificity and binding properties were assessed in vitro. In vivo specificity and biodistribution of 125I-AbD19384 were next evaluated in tumor-bearing mice using a dual-tumor setup. Finally, AbD19384 was labeled with 124I, and its imaging properties were assessed by small animal PET/CT in tumor bearing mice, and compared with 2-deoxy-2-[18F]fluoro-D-glucose (18F-FDG). In vitro studies demonstrated CD44v6-specific binding with slow off-rate for AbD19384. A favorable biodistribution profile was seen in vivo, with tumor-specific uptake. Small animal PET/CT images of 124I-AbD19384 supported the results through clearly visible high CD44v6-expressing tumors and faintly visible low expressing tumors, with superior imaging properties compared to 18F-FDG. Tumor-to-blood ratios increased with time for the conjugate (assessed up to 72 h p.i.), although 48 h p.i. proved best for imaging. Biodistribution and small-animal PET studies demonstrated that the recombinant Fab-dHLX construct AbD19384 is a promising tracer for imaging of CD44v6 antigen expression in vivo, with the future aim to be used for individualized diagnosis and early detection of squamous cell carcinomas in the head and neck region. Furthermore, this proof-of-concept research established the feasibility of using recombinant Fab-dHLX constructs for in vivo imaging of tumor biomarkers.
... This mAb is widely used in the treatment of B-cell malignancies and has significantly improved clinical outcome of patients. The success of rituximab sparked the development of multiple mAbs against a variety of targets for the treatment of hematologic or solid malignancies (2). ...
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Nowadays, it is impossible to imagine modern cancer treatment without targeted therapies, such as mAbs, that bind to tumor-associated antigens. Subsequently, mAbs can use a wide range of effector functions that mostly engage the immune system. mAbs can bridge immune effector cells with tumor cells, which can result in antibody-dependent cytotoxicity. Increasing evidence, however, identified macrophages as prominent effector cells and induction of antibody-dependent cell phagocytosis as one of the primary mechanisms of action mediated by mAbs. Macrophages are extremely effective in eliminating tumor cells from the circulation. Several immunosuppressive mechanisms may, however, hamper their function, particularly in solid malignancies. In this review, we discuss the evolving insight of macrophages as effector cells in mAb therapy and address novel (co)therapeutic strategies that may be used to fully unleash their cytotoxic capacity for the treatment of cancer. Cancer Res; 75(23); 1-6. ©2015 AACR.
... A growing number of humanized mAbs directed against tumor-specific cell surface antigens have been approved by the FDA and are successfully used in the clinic, either as a monotherapy or in combination with chemotherapy. 23 Since surgery is still a main cancer treatment modality, targeted contrast agents for image-guided surgery will increasingly help to facilitate accurate tumor resection. 2,4 When labeled with optical "beacons", such as in the case of mAb−fluorophore conjugates, these contrast agents have proven highly useful for early cancer ...
... It provided protection in animals and demonstrated relative safety in humans, but further studies are required to define the optimal doses and boosters required to A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT 7 achieve a long-lasting response [10,12,13]. Therapeutic antibodies are widely used in the clinic ( [14][15][16]) and offer substantial advantages for post-exposure treatment of ricin intoxication, as toxicity should be low and they have demonstrated efficacy in animals. Postexposure administration of neutralizing anti-ricin monoclonal antibodies (mAbs), delivered locally into the lungs, was effective for rescuing mice from toxin-induced poisoning [11,[17][18][19][20]. Maximal efficacy was reached within hours of exposure, before the appearance of the first symptoms of intoxication. ...
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The high toxicity of ricin and its ease of production have made it a major bioterrorism threat worldwide. There is however no efficient and approved treatment for poisoning by ricin inhalation, although there have been major improvements in diagnosis and therapeutic strategies. We describe the development of an anti-ricin neutralizing monoclonal antibody (IgG 43RCA-G1) and a device for its rapid and effective delivery into the lungs for an application in humans. The antibody is a full-length IgG and binds to the ricin A-chain subunit with a high affinity (KD = 53 pM). Local administration of the antibody into the respiratory tract of mice 6 h after pulmonary ricin intoxication allowed the rescue of 100% of intoxicated animals. Specific operational constraints and aerosolization stresses, resulting in protein aggregation and loss of activity, were overcome by formulating the drug as a dry-powder that is solubilized extemporaneously in a stabilizing solution to be nebulized. Inhalation studies in mice showed that this formulation of IgG 43RCA-G1 did not induce pulmonary inflammation. A mesh nebulizer was customized to improve IgG 43RCA-G1 deposition into the alveolar region of human lungs, where ricin aerosol particles mostly accumulate. The drug delivery system also comprises a semi-automatic reconstitution system to facilitate its use and a specific holding chamber to maximize aerosol delivery deep into the lung. In vivo studies in monkeys showed that drug delivery with the device resulted in a high concentration of IgG 43RCA-G1 in the airways for at least 6 h after local deposition, which is consistent with the therapeutic window and limited passage into the bloodstream.
... For this reason, we produced mAbs decorated with fucose-free, human-type N-glycans (22). Such structures are considered "glycan-optimized," and they are the basis for next generation antibodies in cancer therapies (34) and other indications (16). As expected, PG9 and RSH produced in ΔXT/FT plants contained, in all cases, less than 5% fucosylated glycans. ...
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Broadly neutralizing anti-HIV-1 monoclonal antibodies, such as PG9, and its derivative RSH hold great promise in AIDS therapy and prevention. An important feature related to the exceptional efficacy of PG9 and RSH is the presence of sulfated tyrosine residues in their antigen-binding regions. To maximize antibody functionalities, we have now produced glycan-optimized, fucose-free versions of PG9 and RSH in Nicotiana benthamiana. Both antibodies were efficiently sulfated in planta on coexpression of an engineered human tyrosylprotein sulfotransferase, resulting in antigen-binding and virus neutralization activities equivalent to PG9 synthesized by mammalian cells ((CHO)PG9). Based on the controlled production of both sulfated and nonsulfated variants in plants, we could unequivocally prove that tyrosine sulfation is critical for the potency of PG9 and RSH. Moreover, the fucose-free antibodies generated in N. benthamiana are capable of inducing antibody-dependent cellular cytotoxicity, an activity not observed for (CHO)PG9. Thus, tailoring of the antigen-binding site combined with glycan modulation and sulfoengineering yielded plant-produced anti-HIV-1 antibodies with effector functions superior to PG9 made in CHO cells.
... As antibody-based therapeutics, full-length monoclonal antibodies (mAbs) have proven successful as drugs and remain unrivaled so far in spite of their drawback such as costly and timeconsuming production in mammalian cell lines. In fact, most approved mAbs and those in regulatory review are canonical IgG antibodies [26,27]. Among numerous methods to identify human mAbs, phage display is a powerful tool that enables to display proteins and peptides on the surface of phage, which can be applied to study protein-protein interactions, define epitopes, identify enzyme inhibitors, screen antibody libraries, and to identify agonists and antagonists of cellular receptors [28][29][30]. ...
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YKL-40, also known as chitinase-3-like 1 (CHI3L1), is a glycoprotein that is expressed and secreted by various cell types, including cancers and macrophages. Due to its implications for and upregulation in a variety of diseases, including inflammatory conditions, fibrotic disorders, and tumor growth, YKL-40 has been considered as a significant therapeutic biomarker. Here, we used a phage display to develop novel monoclonal antibodies (mAbs) targeting human YKL-40 (hYKL-40). Human synthetic antibody phage display libraries were panned against a recombinant hYKL-40 protein, yielding seven unique Fabs (Antigen-binding fragment), of which two Fabs (H1 and H2) were non-aggregating and thermally stable (75.5 °C and 76.5 °C, respectively) and had high apparent affinities (KD = 2.3 nM and 4.0 nM, respectively). Reformatting the Fabs into IgGs (Immunoglobulin Gs) increased their apparent affinities (notably, for H1 and H2, KD = 0.5 nM and 0.3 nM, respectively), presumably due to the effects of avidity, with little change to their non-aggregation property. The six anti-hYKL-40 IgGs were analyzed using a trans-well migration assay in vitro, revealing that three clones (H1, H2, and H4) were notably effective in reducing cell migration from both A549 and H460 lung cancer cell lines. The three clones were further analyzed in an in vivo animal test that assessed their anti-cancer activities, demonstrating that the tumor area and the number of tumor nodules were significantly reduced in the lung tissues treated with H1 (IgG). Given its high affinity and desirable properties, we expect that the H1 anti-hYKL-40 mAb will be a suitable candidate for developing anti-cancer therapeutics.
... [59] Studies have shown that high expression of cyclin D1 in glioma cells can lead to uncontrolled cell proliferation, and cyclin D1 can also bind to histone deacetylase to promote its own transcription. [60][61][62] After treatment with deacetylase inhibitors, the expression of cyclin D1 protein in glioma stem cells decreased, and the cell cycle was blocked in the G1 phase. The possible causes include the downregulation of the expression of cyclin D1 resulting in glioma stem cells being unable to enter S phase and the decrease in cyclin D1 gene expression induced via the inhibition of cyclin D1 and histone deacetylase binding. ...
Article
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Glioma is the most common primary tumor of the central nervous system. In addition to traditional anticancer drugs, some common nonchemotherapeutic drugs have been considered by some scholars, such as nonsteroidal anti-inflammatory drugs, metformin, and statins. These drugs are often used for the treatment of noncancerous diseases. However, it was found that those drugs could be considered for the clinical treatment of glioma, especially in combination with chemotherapy drugs, which may improve the treatment effect. This process is called “repurposing.” Here, we aim to review these drugs and the literature. These “old drugs” have been used clinically for many years, and their safety and feasibility are high. Such combinations are expected to become a new strategy in chemotherapy for glioma in the clinic.
... By blocking this family of tyrosine kinase receptors that are overexpressed in different types of tumors, the downstream signaling involved in uncontrolled cell proliferation is also inhibited. It has also been shown that there are immune responses associated with this pharmacological activity [117]. In the search for new therapeutic entities with the same mechanism of action, 7A7 emerged as a therapeutic analogue of cetuximab in mice. ...
Article
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Immunogenic cell death (ICD) elicited by cancer therapy reshapes the tumor immune microenvironment. A long-term adaptative immune response can be initiated by modulating cell death by therapeutic approaches. Here, the major hallmarks of ICD, endoplasmic reticulum (ER) stress, and damage-associated molecular patterns (DAMPs) are correlated with ICD inducers used in clinical practice to enhance antitumoral activity by suppressing tumor immune evasion. Approaches to monitoring the ICD triggered by antitumoral therapeutics in the tumor microenvironment (TME) and novel perspective in this immune system strategy are also reviewed to give an overview of the relevance of ICD in cancer treatment.
... erlotinib and gefitinib) or by monoclonal 15 antibodies (mAbs) [11]. Currently, three monoclonal antibodies (cetuximab, panitumumab, and 16 necitumumab) have been approved for therapeutic applications, but many more are in clinical de-17 velopment [12]. Approved indications include Kirsten rat sarcoma virus (KRAS) wild type colon cancer 18 for cetuximab and panitumumab, head and neck cancer, where only cetuximab has been approved so 19 far as well as non-small cell lung cancer [13]. ...
Preprint
Background & Aims: To enable rapid proliferation, colorectal tumor cells up-regulate epidermal growth factor receptor (EGFR) signaling and perform high level of aerobic glycolysis, resulting in substantial lactate release into the tumor microenvironment and impaired anti-tumor immune responses. We hypothesized that an optimized nutritional intervention designed to reduce aerobic glycolysis of tumor cells may boost EGFR-directed antibody (Ab)-based therapy of pre-existing colitis-driven colorectal carcinoma (CRC). Methods: CRC development was induced by azoxymethane (AOM) and dextran sodium sulfate (DSS) administration to C57BL/6 mice. AOM/DSS treated mice were fed a glucose-free, high-protein diet (GFHPD) or an isoenergetic control diet (CD) in the presence or absence of i.p. injection of PBS, an irrelevant control mIgG2a or an anti-EGFR mIgG2a. Ex vivo, health status, tumor load, metabolism, colonic epithelial cell differentiation and immune cell infiltration were studied. Functional validation was performed in murine and human CRC cell lines MC-38 or HT29-MTX. Results: AOM/DSS treated mice on GFHPD displayed reduced systemic glycolysis, resulting in improved tumoral energy homeostasis and diminished tumor load. Comparable but not additive to an anti-EGFR-Ab therapy, GFHPD was accompanied by enhanced tumoral differentiation and decreased colonic PD-L1 and splenic PD-1 immune checkpoint expression, presumably promoting intestinal barrier function and improved anti-tumor immune responses. In vitro, glucose-free, high-amino acid culture conditions reduced proliferation but improved differentiation of CRC cells in combination with down-regulation of PD-L1 expression. Conclusion: We here found GFHPD to metabolically reprogram colorectal tumors towards balanced OXPHOS, thereby improving anti-tumor T-cell responses and reducing CRC progression with a similar efficacy as EGFR-directed antibody therapy.
... Therapeutically, EGFR can be targeted by small-molecule tyrosine kinase inhibitors (e.g., erlotinib and gefitinib) or by monoclonal antibodies (mAbs) [8]. Currently, three monoclonal antibodies (cetuximab, panitumumab, and necitumumab) have been approved for therapeutic applications, but many more are in clinical development [11]. Approved indications include Kirsten rat sarcoma virus (KRAS), wild-type colon cancer for cetuximab and panitumumab, and head and neck cancer, where only cetuximab has been approved so far, as well as non-small cell lung cancer [12]. ...
Article
Full-text available
To enable rapid proliferation, colorectal tumor cells up-regulate epidermal growth factor receptor (EGFR) signaling and aerobic glycolysis, resulting in substantial lactate release into the tumor microenvironment and impaired anti-tumor immune responses. We hypothesized that a nutritional intervention designed to reduce aerobic glycolysis may boost the EGFR-directed antibody (Ab)-based therapy of pre-existing colitis-driven colorectal carcinoma (CRC). CRC development was induced by azoxymethane (AOM) and dextran sodium sulfate (DSS) administration to C57BL/6 mice. AOM/DSS-treated mice were fed a glucose-free, high-protein diet (GFHPD) or an isoenergetic control diet (CD) in the presence or absence of an i.p. injection of an anti-EGFR mIgG2a or respective controls. AOM/DSS-treated mice on a GFHPD displayed a reduced systemic glucose metabolism associated with reduced oxidative phosphorylation (OXPHOS) complex IV expression and diminished tumor loads. Comparable but not additive to an anti-EGFR-Ab therapy, the GFHPD was accompanied by enhanced tumoral goblet cell differentiation and decreased colonic PD-L1 and splenic CD3e, as well as PD-1 immune checkpoint expression. In vitro, glucose-free, high-amino acid culture conditions reduced proliferation but improved goblet cell differentiation of murine and human CRC cell lines MC-38 and HT29-MTX in combination with down-regulation of PD-L1 expression. We here found GFHPD to systemically dampen glycolysis activity, thereby reducing CRC progression with a similar efficacy to EGFR-directed antibody therapy.
... Humanized and fully human antibodies have the advantage of being retained longer in circulation than their murine equivalents and led to a dramatic increase in the use of antibody-based drugs against cancer. 123,124 However, many challenges have to be overcome for the development of optimized and functional antibody−drug conjugates with possible application as therapeutic agents. ...
Article
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After the first seed concept introduced in the 18th century, different disciplines have attributed different names to dual-functional molecules depending on their application, including bioconjugates, bifunctional compounds, multi targeting molecules, chimeras, hybrids, engineered compounds. However, these engineered constructs share a general structure: a first component which targets a specific cell and a second component that exerts the pharmacological activity. A stable or cleavable linker connects the two modules of a chimera. Herein, we discuss the recent advances in the rapidly expanding field of chimeric molecules leveraging chemical biology concepts. This perspective is focused on bifunctional compounds in which one component is a lead compound or a drug. In details, we discuss chemical features of chimeric molecules, their use for targeted delivery, and for target engagement studies.
... Historically, about 50 % of these Abs recognize tumor Ags [ 273 ]. Although most of these mAbs are in initial development stages, more than one hundred anticancer mAbs are being evaluated in different phases of clinical trials [ 274 ]. Hence, in near future the number of approved mAbs is expected to rise signifi cantly, which could help to improve the outcome of cancer patients by overcoming the current therapeutic limitations. ...
Chapter
Over the past few decades, monoclonal antibodies (mAbs), as potent antitumor tools, have remarkably advanced the cancer therapy, because of their target specificity as well as little “off-target” effects in comparison to most small molecule drugs. The use of antibody engineering methods has made it possible for investigators to develop antibody structures with improved efficacy for application in clinical practice. The development of efficacious therapeutic mAbs entails gaining in-depth knowledge about factors including antibody structure and function, the properties of an ideal tumor antigen, the advantages of employing combinational therapies, and the limitations of antibody-based modalities. This chapter concentrates on mAbs as versatile platforms for cancer immunotherapy.
... The use of monoclonal antibodies (mAbs) in cancer therapies is rapidly increasing. These therapies include general checkpoint inhibitors such as α-CTLA4 (cytotoxic T-lymphocyte-associated protein-4) or α-PD-1/PD-1L (programmed cell death-1 Ligand), and tumor specific antibodies [1][2][3]. To enhance antibody effector functions, various novel formats have been developed [4], including formats such as bispecific antibodies and mini/nanobodies that can be formulated to trigger novel effector functions [5]. ...
Article
Full-text available
Promising strategies for maximizing IgG effector functions rely on the introduction of natural and non-immunogenic modifications. The Fc domain of IgG antibodies contains an N-linked oligosaccharide at position 297. Human IgG antibodies lacking the core fucose in this glycan have enhanced binding to human (FcγR) IIIa/b, resulting in enhanced antibody dependent cell cytotoxicity and phagocytosis through these receptors. However, it is not yet clear if glycan-enhancing modifications of human IgG translate into more effective treatment in mouse models. We generated humanized hIgG1-TA99 antibodies with and without core-fucose. C57Bl/6 mice that were injected intraperitoneally with B16F10-gp75 mouse melanoma developed significantly less metastasis outgrowth after treatment with afucosylated hIgG1-TA99 compared to mice treated with wildtype hhIgG1-TA99. Afucosylated human IgG1 showed stronger interaction with the murine FcγRIV, the mouse orthologue of human FcγRIIIa, indicating that this glycan change is functionally conserved between the species. In agreement with this, no significant differences were observed in tumor outgrowth in FcγRIV-/- mice treated with human hIgG1-TA99 with or without the core fucose. These results confirm the potential of using afucosylated therapeutic IgG to increase their efficacy. Moreover, we show that afucosylated human IgG1 antibodies act across species, supporting that mouse models can be suitable to test afucosylated antibodies.
... Therapeutically, EGFR can be targeted by small-molecule tyrosine kinase inhibitors (e.g., erlotinib and gefitinib) or by monoclonal antibodies (mAbs) [8]. Currently, three monoclonal antibodies (cetuximab, panitumumab, and necitumumab) have been approved for therapeutic applications, but many more are in clinical development [11]. Approved indications include Kirsten rat sarcoma virus (KRAS), wild-type colon cancer for cetuximab and panitumumab, and head and neck cancer, where only cetuximab has been approved so far, as well as non-small cell lung cancer [12]. ...
Article
Full-text available
To enable rapid proliferation, colorectal tumor cells up-regulate epidermal growth factor receptor (EGFR) signaling and aerobic glycolysis, resulting in substantial lactate release into the tumor microenvironment and impaired anti-tumor immune responses. We hypothesized that a nutritional intervention designed to reduce aerobic glycolysis may boost the EGFR-directed antibody (Ab)-based therapy of pre-existing colitis-driven colorectal carcinoma (CRC). CRC development was induced by azoxymethane (AOM) and dextran sodium sulfate (DSS) administration to C57BL/6 mice. AOM/DSS-treated mice were fed a glucose-free, high-protein diet (GFHPD) or an isoenergetic control diet (CD) in the presence or absence of an i.p. injection of an anti-EGFR mIgG2a or respective controls. AOM/DSS-treated mice on a GFHPD displayed a reduced systemic glucose metabolism associated with reduced oxidative phosphorylation (OXPHOS) complex IV expression and diminished tumor loads. Comparable but not additive to an anti-EGFR-Ab therapy, the GFHPD was accompanied by enhanced tumoral goblet cell differentiation and decreased colonic PD-L1 and splenic CD3ε, as well as PD-1 immune checkpoint expression. In vitro, glucose-free, high-amino acid culture conditions reduced proliferation but improved goblet cell differentiation of murine and human CRC cell lines MC-38 and HT29-MTX in combination with down-regulation of PD-L1 expression. We here found GFHPD to systemically dampen glycolysis activity, thereby reducing CRC progression with a similar efficacy to EGFR-directed antibody therapy.
... Meeting this challenge would also be very beneficial in efforts towards producing therapeutic glycoproteins on which core fucosylation can have a considerable effect. For example, monoclonal antibodies (mAbs) raised for cancer immunotherapy can be used in treatments to selectively kill cancer cells through antibody-directed cell-mediated cytotoxicity (ADCC), which is greatly enhanced in cancer-targeting mAbs devoid of core fucosylation since they bind Fcγ receptor IIIA (FcγRIIIA; CD16) on natural killer (NK) cells more tightly than those with core-fucosylated N-glycans [16][17][18][19][20]. ...
Preprint
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We report a straight-forward enzymatic synthesis of the 4-methylumbelliferyl glycoside of a complex-type oligosaccharide substrate for core-fucosylation. We demonstrate the use of this synthetic glycoconjugate in a newly developed enzyme assay to probe the activity and inhibition of fucosyltransferase VIII, which catalyzes the core fucosylation of N -glycans on eukaryotic glycoproteins. In this fucosyltransferase assay, we use the fluorogenic probe and a specific glycosidase in a sequential coupled enzyme reaction to distinguish an unmodified 4-methylumbelliferyl oligosaccharide probe from a fucosylated probe. Our findings show that this strategy is very sensitive and very specific in its detection of enzyme activity and can even be used for analyzing impure tissue lysate samples.
... Synergistic action can be expected with cytotoxic payload and mAb combination therapy. 17 [18][19][20] A combination of humanized or nonhumanized mAb and potential small molecules as chemotherapeutic payloads introduced a new class of cancer therapy, antibody drug conjugates (ADCs). 21 Typical ADC comprises three components, the mAb, a linker, and a cytotoxic payload ( Figure 1). ...
Article
Full-text available
Previously, cancer chemotherapy was often accompanied by severe side effects. Antibody drug conjugates (ADCs) were introduced to address this treatment complication. ADCs are a potent category of bioconjugates and immunoconjugates designed as targeted therapy for the treatment of cancer. ADCs are complex molecules composed of an antibody linked via linker chemistry to a cytotoxic payload or drug. Therefore, biologic properties of the cell‐surface target antigen are important in designing an effective ADC as an anticancer agent. ADCs have the ability to discriminate between the healthy and diseased tissue, so that healthy cells are less effected and get maximum therapeutic benefit. This review describes the development, characterization, and regulatory consideration of ADCs, and it summarizes the approved products in the market and in clinical trials.
... Directly targeting tumors via monoclonal antibodies (mAb) can be an effective strategy to reduce tumor burden, as illustrated by the clinical use of anti-CD20, anti-EGFR (epidermal growth factor receptor) or anti-HER2 (human epidermal growth factor receptor 2) mAb for treating lymphoma, colorectal and breast cancer respectively [46]. Multiple modes of action have been proposed for mAb, including Fc-independent effects as well as Fc-dependent mechanisms such as complement-dependent cytotoxicity (CDC), antibody-dependent cellular cytotoxicity (ADCC) or phagocytosis (ADP) [47]. ...
Article
Full-text available
Understanding complex interactions between the immune system and the tumor microenvironment is an essential step towards the rational development and optimization of immunotherapies. Several experimental approaches are available to tackle this complexity but most are not designed to address the dynamic features of immune reactions, including cell migration, cellular interactions, and transient signaling events. By providing a unique means to access these precious parameters, intravital imaging offers a fresh look at intratumoral immune responses at the single-cell level. Here, we discuss how in vivo imaging sheds light on fundamental aspects of tumor immunity and helps elucidate modes of action of immunotherapies. We conclude by discussing future developments that may consolidate the unique contribution of intravital imaging for our understanding of tumor immunity.
... However, the use of chemotherapeutic drugs faces constant limitations in terms of non-specificity, meaning that they kill not only the tumor cells but also healthy cells and cause serious adverse reactions, narrow therapeutic windows, and increased drug resistance [7][8][9][10][11][12][13]. Targeted drug therapy could potentially address these challenges, as it facilitates the delivery of drug agents to unhealthy cells without harming healthy ones [14][15][16][17][18][19][20]. Antibodies are a rapidly growing class of drug that play a major role in human health, mostly in oncology, autoimmunity and chronic inflammatory diseases [21][22][23]. ...
Article
Full-text available
As one of the major therapeutic options for cancer treatment, chemotherapy has limited selectivity against cancer cells. Consequently, this therapeutic strategy offers a small therapeutic window with potentially high toxicity and thus limited efficacy of doses that can be tolerated by patients. Antibody-drug conjugates (ADCs) are an emerging class of anti-cancer therapeutic drugs that can deliver highly cytotoxic molecules directly to cancer cells. To date, twelve ADCs have received market approval, with several others in clinical stages. ADCs have become a powerful class of therapeutic agents in oncology and hematology. ADCs consist of recombinant monoclonal antibodies that are covalently bound to cytotoxic chemicals via synthetic linkers. The linker has a key role in ADC outcomes because its characteristics substantially impact the therapeutic index efficacy and pharmacokinetics of these drugs. Stable linkers and ADCs can maintain antibody concentration in blood circulation, and they do not release the cytotoxic drug before it reaches its target, thus resulting in minimum off-target effects. The linkers used in ADC development can be classified as cleavable and non-cleavable. The former, in turn, can be grouped into three types: hydrazone, disulfide, or peptide linkers. In this review, we highlight the various linkers used in ADC development and their design strategy, release mechanisms, and future perspectives.
... Os produtos biológicos e biotecnológicos têm ocupado um lugar central no âmbito da pesquisa e do desenvolvimento, especialmente a partir da década de 1980, quando a farmacologia se reinventou com o surgimento de produtos produzidos por nova rota de síntese -a biotecnológica, objetivando oferecer opções voltadas à medicina personalizada e à terapêutica direcionada 1,2,3 . A Agência Nacional de Vigilância Sanitária (Anvisa) distingue seis principais grupos de produtos biológicos: (1) vacinas; (2) soros hiperimunes; (3) hemoderivados; (4) biomedicamentos obtidos a partir de fluidos biológicos, tecidos de origem animal ou a partir de procedimentos biotecnológicos; (5) medicamentos contendo microrganismos vivos, atenuados ou mortos; e (6) anticorpos monoclonais (mABs) 4 . ...
Article
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Resumo: Os anticorpos monoclonais (mABs) têm sido indicados como tecnologia inovadora para o tratamento de alguns tipos de câncer, por serem capazes de alvejar e matar seletivamente células tumorais. Contudo, os altos custos dessas terapias colocam em questão a sustentabilidade do acesso. Este trabalho teve como objetivo identificar as principais características dos anticorpos monoclonais, destinados ao tratamento de câncer, com registro sanitário ativo, no Brasil, em 2016. Tratou-se de uma análise descritiva retrospectiva a partir de consulta à página de Internet da Agência Nacional de Vigilância Sanitária (Anvisa), em que esses mABs foram caracterizados de acordo com antígeno-alvo, tipo de anticorpo, ano de registro, indicações terapêuticas e empresa detentora do registro. Foram identificados 14 anticorpos com ação em sete antígenos-alvo diferentes. No que diz respeito às indicações clínicas, houve uma maior frequência de linfomas, leucemias, câncer de mama e câncer colorretal. Quanto ao tipo, foram identificados três anticorpos quiméricos, seis humanizados e cinco humanos. A Roche apareceu como a empresa detentora do registro de 6 dos 14 mABs, o que representa 43% dos registros sanitários. Foi possível, a partir desses dados, discutir a ideia de medicamentos me-too no mercado de biológicos, assim como pensar as tensões existentes nesse mercado e a ideia de oligopólio diferenciado. Apesar do desenvolvimento de novos produtos, ainda que para atuar em um mesmo alvo, representar a possibilidade de um incremento competitivo e, com isso, de uma diminuição dos preços praticados pelas empresas torna-se um problema quando é a mesma empresa que lança no mercado novos anticorpos direcionados ao mesmo alvo, sem mudanças relevantes.
Article
Antibodies (Abs) are a major constituent of the human immune system and have become an important class of therapeutics in cancer and inflammatory diseases. Antibody engineering technologies aim at the development of new generations of antibody-based drugs with more favorable properties, including higher potency or improved safety profiles. This chapter provides an overview over current strategies to tailor Abs for medical applications. While some of the engineering technologies improve the inherent features of the antibody-like target specificity, effector functions, or pharmacokinetics-others empower the antibody with additional mechanisms of action. The latter category includes the development of antibody-drug conjugates (ADCs), radioimmunoconjugates, or bispecific Abs. These novel antibody-based therapeutics will likely have a big impact on the future treatment of many diseases, but especially in cancer therapy.
Chapter
This chapter describes the different types of bispecific formats as well as the principles used to generate them, before elaborating on the biochemical and pharmacological properties including affinity, avidity, and pharmacokinetics (PK). In addition, assay strategies to measure these compounds and the use of pharmacokinetic/pharmacodynamic (PK/PD) modeling in the design and development of these complex molecules are also covered. Next, the chapter highlights some of the key properties of bispecific antibodies (bsAbs) that may be considered or leveraged while developing these novel and complex therapeutics. The overall PK behavior of the bsAb is strongly dependent on the format. BsAbs based on immunoglobulin G (IgG) may be preferred due to the favorable PK properties (e.g., long serum half-life) as well as the option to modulate the effector functions. Finally, it presents three case studies to highlight some of the challenges in the research and development of bsAbs.
Chapter
Antibody therapeutics is a thriving field with currently over thirty treatments that are approved primarily for oncology and inflammatory disorders. Antibodies have many advantages as drugs, including high specificity to their targets, long half-lives, and generally highly favorable toxicity profiles. The majority of the currently approved antibody therapeutics are conventional immunoglobulin Gs directed at a single target. However, as the field of protein engineering has advanced, a significant number of new antibody-like formats have been developed that possess robust bioactivity and manufacturability profiles. A number of these molecules have demonstrated superiority to conventional monoclonal antibodies in preclinical settings and have entered clinical testing. This review will discuss engineering of antibody-like molecules that optimize efficacy by targeting multiple receptors or by incorporating additional mechanisms of action, including altered effector function against established therapeutic targets. These molecules are commonly termed biobetters, which, formally speaking, are biologic drugs that are developed against previously validated target antigens but have some properties that are superior compared to currently approved products for commercial use.
Chapter
A monoclonal antibody (MAb) is an antibody made from a single clone (hybridoma) of white blood cells. MAbs are used to block key receptors on tumor cell surfaces, compromising their function. MAbs may also be used to recruit the cellular arm of the immune system, planting a homing beacon on the transformed cell. MAbs, although produced in the laboratory, mimic the antibodies naturally produced by the body as part of immune system’s response to disease. The remarkable specificity of MAbs is also being harnessed in other ways, e.g., they are being paired with powerful toxins to create specific agents that seek out cancer cells and kill them. MAbs are also being employed for diagnosis, helping to identify the source of a tumor and provide a possibility for the treatment. MAbs enable the combination of diagnostics with therapeutics.
Article
Since the turn of the century, cancer therapy has undergone a transformation in terms of new treatment modalities and renewed optimism in achieving long-lived tumor control and even cure. This is, in large part, thanks to the widespread incorporation of monoclonal antibodies (mAbs) into standard treatment regimens. These new therapies have, across many settings, significantly contributed to improved clinical responses, patient quality of life and survival. Moreover, the flexibility of the antibody platform has led to the development of a wide range of innovative and combinatorial therapies that continue to augment the clinician's armory. Despite these successes, there is a growing awareness that in many cases mAb therapy remains suboptimal, primarily due to inherent limitations imposed by the immune system's own homeostatic controls and the immunosuppressive tumor microenvironment. Here, we discuss the principal barriers that act to constrain the tumor-killing activity of antibody-based therapeutics, particularly those involving antibody glycans, using illustrative examples from both pre-clinical and market approved mAbs. We also discuss strategies that have been, or are in development to overcome these obstacles. Finally, we outline how the growing understanding of the biological terrain in which mAbs function is shaping innovation and regulation in cancer therapeutics.
Article
Affinity modulation of antibodies and antibody fragments of therapeutic value is often required in order to improve their clinical efficacies. Virtual affinity maturation has the potential to quickly focus on the critical hotspot residues without the combinatorial explosion problem of conventional display and library approaches. However, this requires a binding affinity scoring function that is capable of ranking single-point mutations of a starting antibody. We focus here on assessing the solvated interaction energy function (SIE) that was originally developed for and is widely applied to scoring protein-ligand binding affinities. To this end, we assembled a structure-function data set called SiPMAB (Single-Point Mutant Antibody Binding) comprising several antibody-antigen systems suitable for this assessment, i.e., based on high-resolution crystal structures for the parent antibodies, and coupled with high-quality binding affinity measurements for sets of single-point antibody mutants in each system. Using this data set we tested the SIE function with several mutation protocols based on the popular methods SCWRL, Rosetta and FoldX. We find that the SIE function coupled with a protocol limited to sampling only the mutated side-chain can reasonably predict relative binding affinities with a Spearman rank-order correlation coefficient of about 0.6, outperforming more aggressive sampling protocols. Importantly, this performance is maintained for the 7 component system-specific subsets as well as for other relevant subsets including non-alanine and charge-altering mutations. The transferability and enrichment in affinity-improving mutants can be further enhanced using consensus ranking over multiple methods including the SIE, Talaris and FOLDEF energy functions. The knowledge gained from this study can lead to successful prospective applications of virtual affinity maturation.
Chapter
Optical tweezers?assisted dynamic force spectroscopy is employed to investigate specific receptor?ligand interactions on the level of single binding events. In this regard, the binding between three antihuman tau monoclonal antibodies (mAbs) and synthetic tau-peptides with different phosphorylation patterns are presented. Furthermore, we introduce the basic concepts of optical tweezers and show how to analyze the experimental data in order to extract specific binding parameters. From this single-molecule approach, a detailed understanding of such noncovalent bonds can be gained. Additionally, we propose a method for differentiating between unspecific and specific interactions, showing how DFS can offer important insights about the dynamic binding process that are not accessible through common and widespread ensemble techniques.
Article
Bispecific antibody constructs (Bispecifics, bsAbs) may have greater functionality compared to established monoclonal antibodies because they bind to 2 different targets or, potentially, to 2 epitopes on the same target (dual targeting). This may result in enhanced binding avidity with preferential binding to cells that express both targets or binding to targets on different cells. However, development of these next-generation biologics, including new formats, creates unique challenges due to their increased complexity. Here we review aspects of bsAbs preclinical development programs that may increase the success rates of bsAbs in clinical development.
Article
Stability of therapeutic proteins (TPs) is a critical quality attribute that impacts both safety and efficacy of the drug. Size stability is routinely performed during and after biomanufacturing. Dynamic light scattering is a commonly used technique to characterize hydrodynamic (HD) size of the TPs. Herein we have developed a novel method to evaluate in-use and thermal stress stability of TPs using algorithm-driven high throughput dynamic light scattering (HTS-DLS). Five marketed TPs were tested under the guidance of customized algorithms. The TPs were evaluated at relevant temperature conditions as well as under dilution and thermal stress for size stability. We found that the TPs were stable under the in-use conditions tested however sample loss due to evaporation can lead to large protein aggregates. A combined assessment of autocorrelation function and photos of sample well images could be useful in formulation screening. Dilution of TPs also have an impact on the HD size. Thermal stress experiments showed the importance of using different data processing methods to access size distribution. Polydispersity index was useful in evaluating sample heterogeneity. Herein we show that algorithm-driven HTS-DLS can provide additional supportive information during and after biomanufacturing and the potential to be used in a QC environment.
Article
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Bispecific antibodies are considered attractive bio-therapeutic agents owing to their ability to target two distinct disease mediators. Cross-arm avidity targeting of antigen double-positive cancer cells over single-positive normal tissue is believed to enhance the therapeutic efficacy, restrict major escape mechanisms and increase tumor-targeting selectivity, leading to reduced systemic toxicity and improved therapeutic index. However, the interplay of factors regulating target selectivity is not well understood and often overlooked when developing clinically relevant bispecific therapeutics. We show in vivo that dual targeting alone is not sufficient to endow selective tumor-targeting, and report the pivotal roles played by the affinity of the individual arms, overall avidity and format valence. Specifically, a series of monovalent and bivalent bispecific IgGs composed of the anti-HER2 trastuzumab moiety paired with affinity-modulated VH and VL regions of the anti-EGFR GA201 mAb were tested for selective targeting and eradication of double-positive human NCI-H358 non-small cell lung cancer target tumors over single-positive, non-target NCI-H358-HER2 CRISPR knock out tumors in nude mice bearing dual-flank tumor xenografts. Affinity-reduced monovalent bispecific variants, but not their bivalent bispecific counterparts, mediated a greater degree of tumor targeting selectivity, while the overall efficacy against the targeted tumor was not substantially affected.
Article
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Colorectal cancer is considered a disease of the elderly population. Since the number of geriatric patients continues to rise, monoclonal antibody therapy is the most promising therapy in the recent research. Presently, the monoclonal antibodies most frequently used in the treatment of colorectal tumors are bevacizumab, cetuximab, panitumumab, and ramucirumab. Bevacizumab is a monoclonal antibody that acts on VEGF. Cetuximab and panitumumab act on EGFR. Ramucirumab binds directly to the ligand-binding pocket of VEGFR-2 to block the binding of VEGF-A, VEGF-C, and VEGF-D. These monoclonal antibodies, alone or in association with radiotherapy or chemotherapy, are presenting good results and are increasing patient survival, despite the side effects. Due to the limited number of molecules available, several studies are trying to develop new monoclonal antibodies for the treatment of colorectal tumors. Among those being studied, some recent molecules are in phase I and/or II trials and are yielding advantageous results, such as anti-DR5, anti-Fn14, anti-IGF-1R, anti-EGFR, anti-NRP1, and anti-A33 antibodies. This has been successful in reducing side effects and in treating nonresponsive patients.
Chapter
In this chapter we aim at describing a new class of biologics in development for rheumatoid arthritis (RA), bispecific antibodies (bsAbs). These recognize two different specificities, and in most cases targets, as implied in their name. These bring about a series of interesting questions related to target selection, potential mode of action, pharmacokinetics (PK), and whether their development differs from classical biologics. BsAb is a very dynamic field, and therefore it was not possible to review all preclinical developments in inflammatory diseases and RA in details here. As we feel a look at where bispecific antibodies have evolved from is instructive, we start this chapter with some of the main mode of actions and targets of biologics registered for RA, including combination of biologics which were tested in the clinic. We then address pathway and target selection and go over a series of points to consider where bsAbs may require special attention when compared to classical biologics for development. Related to mode of action and target is the selection of the right molecular format. We provide an overview on bsAb formats and then go more specifically over those used in molecules in development for RA and some inflammatory diseases. Finally, we provide an outlook on where this field might develop in the coming years.
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We report a straight-forward enzymatic synthesis of the 4-methylumbelliferyl glycoside of a complex-type oligosaccharide substrate for core-fucosylation. We demonstrate the use of this synthetic glycoconjugate in a newly developed enzyme assay to probe the activity and inhibition of fucosyltransferase VIII, which catalyzes the core fucosylation of N-glycans on eukaryotic glycoproteins. In this fucosyltransferase assay, we use the fluorogenic probe and a specific glycosidase in a sequential coupled enzyme reaction to distinguish an unmodified 4-methylumbelliferyl oligosaccharide probe from a fucosylated probe. Our findings show that this strategy is very sensitive and very specific in its detection of enzyme activity and can even be used for analyzing impure tissue lysate samples.
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Introduction: Trastuzumab, a therapeutic monoclonal antibody directed against ErbB2, is often noted as a successful example of targeted therapy. Trastuzumab improved outcomes for many patients with ErbB2-positive breast and gastric cancers, however, cardiac side effects [e.g., left ventricular dysfunction and congestive heart failure (CHF)] were reported in the early phase clinical studies. This finding, subsequently corroborated by multiple clinical studies, raised concerns that the observed cardiotoxicity induced by trastuzumab might adversely impact the clinical development of other therapeutics targeting ErbB family members. Areas covered: In this review we summarize both basic research and clinical findings regarding trastuzumab-induced cardiotoxicity and assess if there has been an impact of trastuzumab-induced cardiotoxicity on the development of other agents targeting ErbB family members. Expert opinion: There are a number of scientific gaps that are critically important to address for the continued success of HER2-targeted agents. These include: 1) elucidating the molecular mechanisms contributing to cardiotoxicity; 2) developing relevant preclinical testing systems for predicting cardiotoxicity; 3) developing clinical strategies to identify patients at risk of cardiotoxicity; and 4) enhancing management of clinical symptoms of cardiotoxicity.
Chapter
Trimerbodies, with their unique structural and functional properties, are the basis of a new generation of therapeutic antibodies, which due to their small size and plasticity are ideal for the generation of novel biological protein drugs with multiple competitive advantages over conventional full-length monoclonal antibodies. Since their emergence, trimerbodies have been used in preclinical cancer diagnosis and therapy. Trimerbodies are highly adaptable molecules, as they allow target-specific modulation of T cell–mediated anti-tumor immunity to enhance preexisting responses or to generate de novo immune responses. In fact, a tumor-specific humanized 4-1BB-agonistic trimerbody has shown a rather impressive safety and efficacy profile in preclinical studies making it a realistic option for clinical development. Moreover, thanks to the avidity effect they are endowed with considerable therapeutic potential as carriers to deliver cytotoxic payloads to tumors. In addition, molecular imaging studies could benefit from some intermediate-sized trivalent trimerbodies as promising candidates for targeted therapy and tumor imaging.
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The aim of this thesis is to generate qualified information about technologies that may be relevant to cancer care in the next 30 years (2017-2047). We used technology foresight framework to deepen concepts and incorporate methods for future technologies research. The research focused on technologies developed from biotechnological tools (or biopharmaceuticals). For the identification of future technologies, a method was developed from the consultation of editorials of journals specialized in oncology. This method allowed the selection of nine technologies with the potential to have a future impact on cancer care. In addition, a method of consulting a large number of experts was developed from e-mail from authors of indexed articles in the Thomson Reuters’ Web of Science database. In this survey, more than 83,000 cancer specialists were invited to report, through a Web Survey, their expectations about the future of cancer care. The questionnaire was answered by 2,408 specialists - of whom, 1,348 auto declared themselves experts with high knowledge in the subject. The results presented here refer to the answers of high knowledge specialists. These experts pointed out that antibody-related therapies, molecular imaging, and tumor delivery systems are the technologies most likely to be used in cancer care for the next thirty years. Among the reasons pointed out for the choice of these technologies, we highlight, mainly, the improvement in the prognosis of the disease and the greater reliability in the diagnoses. Among the technologies with a low expectation of success, knowledge and scientific barriers were highlighted as the main obstacles to its development.
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An antibody-AIEgen conjugate is designed and developed as a “turn-on” fluorescent probe for wash-free specific cancer cell imaging. The cetuximab-conjugated AIEgen shows red fluorescence only when it is internalized and accumulated in cancer cells with overexpressed epidermal growth factor receptor through endocytosis. The probe first lights up the lysosomes. After hydrolysis, its residue is accumulated in mitochondria, making them highly emissive with long cell retention time. Compared with conventional “always-on” fluorescent probes, the antibody-AIEgen conjugate exhibits a very good image contrast during wash-free cancer cell imaging and less interference from normal cells. To the best of our knowledge, this is the first time to report “turn-on” antibody-AIEgen conjugates. This new strategy can be further extended to many proteins and water-soluble AIEgens, and many of their potential applications such as real-time tracking of cell dynamics and cancer theranostics will be explored. The present work is expected to inspire more marvelous research in the fields of AIE and cancer imaging.
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Monoclonal antibodies are widely used for the treatment of cancer, inflammatory and infectious diseases and other disorders. Most of the marketed antibodies are monospecific and therefore capable of interacting and interfering with a single target. However, complex diseases are often multifactorial in nature, and involve redundant or synergistic action of disease mediators or upregulation of different receptors, including crosstalk between their signaling networks. Consequently, blockade of multiple, different pathological factors and pathways may result in improved therapeutic efficacy. This result can be achieved by combining different drugs, or use of the dual targeting strategies applying bispecific antibodies that have emerged as an alternative to combination therapy. This review discusses the various dual targeting strategies for which bispecific antibodies have been developed and provides an overview of the established bispecific antibody formats.
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Adult T-cell leukemia-lymphoma (ATL) is usually resistant to conventional chemotherapies, and there are few other treatment options. Because CC chemokine receptor 4 (CCR4) is expressed on tumor cells from most patients with ATL, KW-0761, a humanized anti-CCR4 monoclonal antibody, which markedly enhances antibody-dependent cellular cytotoxicity, was evaluated in the treatment of patients with relapsed ATL. A multicenter phase II study of KW-0761 for patients with relapsed, aggressive CCR4-positive ATL was conducted to evaluate efficacy, pharmacokinetic profile, and safety. The primary end point was overall response rate, and secondary end points included progression-free and overall survival from the first dose of KW-0761. Patients received intravenous infusions of KW-0761 once per week for 8 weeks at a dose of 1.0 mg/kg. Of 28 patients enrolled onto the study, 27 received at least one infusion of KW-0761. Objective responses were noted in 13 of 26 evaluable patients, including eight complete responses, with an overall response rate of 50% (95% CI, 30% to 70%). Median progression-free and overall survival were 5.2 and 13.7 months, respectively. The mean half-life period after the eighth infusion was 422 ± 147 hours (± standard deviation). The most common adverse events were infusion reactions (89%) and skin rashes (63%), which were manageable and reversible in all cases. KW-0761 demonstrated clinically meaningful antitumor activity in patients with relapsed ATL, with an acceptable toxicity profile. Further investigation of KW-0761 for treatment of ATL and other T-cell neoplasms is warranted.
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T-cell activation is dependent on signals delivered through the antigen-specific T-cell receptor and accessory receptors on T-cells. Integration of signals through this family of costimulatory and inhibitory receptors and their ligands regulates the balance between T-cell activation, tolerance, and immunopathology. Programmed death 1 (PD-1) and its ligands, PD-L1 and PD-L2, deliver inhibitory signals and exert a vital and diverse range of immunoregulatory roles in T-cell activation, tolerance, and immune-mediated tissue damage. In this review, we revisit current understanding of the immunoregulatory functions of PD-1 and its ligands and their involvement in immune-mediated diseases.
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4-1BB (CD137, TNFRSF9) is a costimulatory receptor expressed on several subsets of activated immune cells. Numerous studies of mouse and human T cells indicate that 4-1BB promotes cellular proliferation, survival, and cytokine production. 4-1BB agonist mAbs have demonstrated efficacy in prophylactic and therapeutic settings in both monotherapy and combination therapy tumor models and have established durable anti-tumor protective T-cell memory responses. PF-05082566 is a fully human IgG2 that binds to the extracellular domain of human 4-1BB with high affinity and specificity. In preclinical studies, this agonist antibody demonstrated its ability to activate NF-κB and induce downstream cytokine production, promote leukocyte proliferation, and inhibit tumor growth in a human PBMC xenograft tumor model. The mechanism of action and robust anti-tumor efficacy of PF-05082566 support its clinical development for the treatment of a broad spectrum of human malignancies.
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Introduction: Cancer is a devastating disease; however, several therapeutic advances have recently been made, wherein EGFR and its family members have emerged as useful biomarkers and therapeutic targets. EGFR, a transmembrane glycoprotein is a member of the ERBB receptor tyrosine kinase superfamily. EGFR binds to its cognate ligand EGF, which further induces tyrosine phosphorylation and receptor dimerization with other family members leading to enhanced uncontrolled proliferation. Several anti-EGFR therapies such as monoclonal antibodies and tyrosine kinase inhibitors have been developed, which has enabled clinicians to identify and treat specific patient cohorts. Areas covered: This review covers the basic mechanism of EGFR activation and the role of EGFR signaling in cancer progression. Furthermore, current developments made toward targeting the EGFR signaling pathway for the treatment of epithelial cancers and a summary of the various anti-EGFR therapeutic agents that are currently in use are also presented in this review. Expert opinion: EGFR signaling is a part of a complex network that has been the target of effective cancer therapies. However, a further understanding of the system is required to develop an effective anticancer regimen. A combination therapy that comprises an anti-EGFR and a chemotherapeutic/chemopreventive agent will exhibit a multi-pronged approach that can be developed into a highly attractive and specific molecular oriented remedy.
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The epidermal growth factor receptor (EGFR) is frequently dysregulated in human malignancies and a validated target for cancer therapy. Two monoclonal anti-EGFR antibodies (cetuximab and panitumumab) are approved for clinical use. However, the percentage of patients responding to treatment is low and many patients experiencing an initial response eventually relapse. Thus, the need for more efficacious treatments remains. Previous studies have reported that mixtures of antibodies targeting multiple distinct epitopes are more effective than single mAbs at inhibiting growth of human cancer cells in vitro and in vivo. The current work describes the rational approach that led to discovery and selection of a novel anti-EGFR antibody mixture Sym004, which is currently in Phase 2 clinical testing. Twenty-four selected anti-EGFR antibodies were systematically tested in dual and triple mixtures for their ability to inhibit cancer cells in vitro and tumor growth in vivo. The results show that targeting EGFR dependent cancer cells with mixtures of antibodies is superior at inhibiting their growth both in vitro and in vivo. In particular, antibody mixtures targeting non-overlapping epitopes on domain III are efficient and indeed Sym004 is composed of two monoclonal antibodies targeting this domain. The superior growth inhibitory activity of mixtures correlated with their ability to induce efficient EGFR degradation.
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Multiple myeloma (MM) patients who receive killer cell Ig-like receptor (KIR) ligand-mismatched, T cell-depleted, allogeneic transplantation may have a reduced risk of relapse compared with patients who receive KIR ligand-matched grafts, suggesting the importance of this signaling axis in the natural killer (NK) cell-versus-MM effect. Expanding on this concept, IPH2101 (1-7F9), an anti-inhibitory KIR mAb, enhances NK-cell function against autologous MM cells by blocking the engagement of inhibitory KIR with cognate ligands, promoting immune complex formation and NK-cell cytotoxicity specifically against MM cell targets but not normal cells. IPH2101 prevents negative regulatory signals by inhibitory KIR, whereas lenalidomide augments NK-cell function and also appears to up-regulate ligands for activating NK-cell receptors on MM cells. Lenalidomide and a murine anti-inhibitory NK-cell receptor Ab mediate in vivo rejection of a lenalidomide-resistant tumor. These mechanistic, preclinical data support the use of a combination of IPH2101 and lenalidomide in a phase 2 trial for MM.
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Trastuzumab emtansine (T-DM1) is a human epidermal growth factor receptor (HER2)-targeted antibody-drug conjugate, composed of trastuzumab, a stable thioether linker, and the potent cytotoxic agent DM1 (derivative of maytansine), in phase III development for HER2-positive cancer. Extensive analysis of T-DM1 in preclinical studies has shown that T-DM1 combines the distinct mechanisms of action of both DM1 and trastuzumab, and has antitumor activity in trastuzumab- and lapatinib-refractory experimental models. Clinically, T-DM1 has a consistent pharmacokinetics profile and minimal systemic exposure to free DM1, with no evidence of DM1 accumulation following repeated T-DM1 doses. Although a few covariates were shown to affect interindividual variability in T-DM1 exposure and clearance in population-pharmacokinetics analyses, the magnitude of their effect on T-DM1 exposure was not clinically relevant. Phase I and phase II clinical trials of T-DM1 as a single agent and in combination with paclitaxel, docetaxel, and pertuzumab have shown clinical activity and a favorable safety profile in patients with HER2-positive metastatic breast cancer. Two randomized phase III trials of T-DM1 are recruiting patients: EMILIA (NCT00829166) is evaluating T-DM1 compared with lapatinib plus capecitabine, and MARIANNE (NCT01120184) is evaluating T-DM1 plus placebo versus T-DM1 plus pertuzumab versus trastuzumab plus a taxane. Additional combinations of T-DM1 (for example, with GDC-0941) and additional disease settings (early-stage HER2-positive breast cancer) are also under investigation. Data from the phase III trials and other studies of T-DM1-containing agents are eagerly awaited.
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Antibody conjugates are a diverse class of therapeutics consisting of a cytotoxic agent linked covalently to an antibody or antibody fragment directed toward a specific cell surface target expressed by tumor cells. The notion that antibodies directed toward targets on the surface of malignant cells could be used for drug delivery is not new. The history of antibody conjugates is marked by hurdles that have been identified and overcome. Early conjugates used mouse antibodies; cytotoxic agents that were immunogenic (proteins), too toxic, or not sufficiently potent; and linkers that were not sufficiently stable in circulation. Investigators have explored 4 main avenues using antibodies to target cytotoxic agents to malignant cells: antibody-protein toxin (or antibody fragment-protein toxin fusion) conjugates, antibody-chelated radionuclide conjugates, antibody-small-molecule drug conjugates, and antibody-enzyme conjugates administered along with small-molecule prodrugs that require metabolism by the conjugated enzyme to release the activated species. Only antibody-radionuclide conjugates and antibody-drug conjugates have reached the regulatory approval stage, and nearly 20 antibody conjugates are currently in clinical trials. The time may have come for this technology to become a major contributor to improving treatment for cancer patients.
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To date, more than 30 antibodies have been approved worldwide for therapeutic use. While the monoclonal antibody market is rapidly growing, the clinical use of therapeutic antibodies is mostly limited to treatment of cancers and immunological disorders. Moreover, antibodies against only five targets (TNF-α, HER2, CD20, EGFR, and VEGF) account for more than 80 percent of the worldwide market of therapeutic antibodies. The shortage of novel, clinically proven targets has resulted in the development of many distinct therapeutic antibodies against a small number of proven targets, based on the premise that different antibody molecules against the same target antigen have distinct biological and clinical effects from one another. For example, four antibodies against TNF-α have been approved by the FDA -- infliximab, adalimumab, golimumab, and certolizumab pegol -- with many more in clinical and preclinical development. The situation is similar for HER2, CD20, EGFR, and VEGF, each having one or more approved antibodies and many more under development. This review discusses the different binding characteristics, mechanisms of action, and biological and clinical activities of multiple monoclonal antibodies against TNF-α, HER-2, CD20, and EGFR and provides insights into the development of therapeutic antibodies.
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Blinatumomab, a bispecific single-chain antibody targeting the CD19 antigen, is a member of a novel class of antibodies that redirect T cells for selective lysis of tumor cells. In acute lymphoblastic leukemia (ALL), persistence or relapse of minimal residual disease (MRD) after chemotherapy indicates resistance to chemotherapy and results in hematologic relapse. A phase II clinical study was conducted to determine the efficacy of blinatumomab in MRD-positive B-lineage ALL. Patients with MRD persistence or relapse after induction and consolidation therapy were included. MRD was assessed by quantitative reverse transcriptase polymerase chain reaction for either rearrangements of immunoglobulin or T-cell receptor genes, or specific genetic aberrations. Blinatumomab was administered as a 4-week continuous intravenous infusion at a dose of 15 μg/m2/24 hours. Twenty-one patients were treated, of whom 16 patients became MRD negative. One patient was not evaluable due to a grade 3 adverse event leading to treatment discontinuation. Among the 16 responders, 12 patients had been molecularly refractory to previous chemotherapy. Probability for relapse-free survival is 78% at a median follow-up of 405 days. The most frequent grade 3 and 4 adverse event was lymphopenia, which was completely reversible like most other adverse events. Blinatumomab is an efficacious and well-tolerated treatment in patients with MRD-positive B-lineage ALL after intensive chemotherapy. T cells engaged by blinatumomab seem capable of eradicating chemotherapy-resistant tumor cells that otherwise cause clinical relapse.
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LFB-R603 is a chimeric anti-CD20 mouse/human monoclonal antibody with a human IgG1 constant (Fc) region. In comparison to rituximab, LFB-R603 exhibits a high affinity to the Fcγ RIII (CD16) and a potent in vitro antibody-dependent cellular cytotoxicity (ADCC). We examined several experimental designs for the biological anti-tumor activity of LFB-R603 as well as its sensitizing activity to apoptosis in resistant non-Hodgin's B-cell lymphoma (B-NHL) in comparison to rituximab. Treatment of the B-NHL cell line Ramos with LFB-R603 was not toxic at the concentrations used and induced cell aggregation following culture at 24 and 48 h similarly to rituximab. Hence, we hypothesized that LFB-R603 may signal the tumor cells and modify intracellular survival/anti-apoptotic pathways. Treatment of Ramos cells with LFB-R603 inhibited the constitutively active NF-κB survival pathway, followed by significant potentiation of TRAIL-mediated apoptosis. We examined the underlying molecular mechanism by which the LFB-R603-mediated NF-κB inhibition results in the reversal of tumor cell resistance to TRAIL. We hypothesized that downstream gene products regulated by NF-κB that are involved in the resistance may be involved in LFB-R603-mediated sensitization. We found that LFB-R603 inhibited NF-κB activation and the anti-apoptotic factor Snail and induced the pro-apoptotic factor RKIP. The direct roles of Snail and RKIP modulation by LFB-R603 in the reversal of B-NHL resistance to TRAIL were examined by knocking down Snail and overexpressing RKIP in Ramos cells, respectively. Both approaches increased significantly the cell sensitivity to TRAIL apoptosis. In addition to changes observed in the expression levels of Snail and RKIP, Ramos cells treated with LFB-R603 induced the expression of PTEN along with inhibition of the PI3K-AKT activated pathway. PTEN silencing in Ramos cells pretreated with LFB-R603 and TRAIL inhibited TRAIL apoptosis; thus, demonstrating that PTEN induction by LFB-R603 has a direct role in tumor cell sensitization to TRAIL apoptosis. Several of the findings obtained in the experimental designs with LFB-R603 were superior to those obtained with rituximab. Overall, the findings demonstrate that LFB-R603 interferes with the dysregulated NF-κB/Snail/RKIP/PTEN/AKT resistance circuitry in B-NHL cells. Further, the findings suggest that LFB-R603 may sensitize tumor cells to various apoptotic stimuli including cytotoxic ligands such as TRAIL and chemotherapeutic drugs.
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The Triomab family of trifunctional, bispecific antibodies that maintain an IgG-like shape are novel tumor targeting agents. These chimeras consist of two half antibodies, each with one light and one heavy chain, that originate from parental mouse IgG2a and rat IgG2b isotypes. This combination allows cost-effective biopharmaceutical manufacturing at an industrial scale since this specific mouse/rat isotype combination favors matching of corresponding antibody halves during production by means of quadroma technology. Whereas every Triomab family member is composed of an anti-CD3 rat IgG2b half antibody for T cell recognition, the antigen binding site presented by the mouse IgG2a isotype is exchangeable. Several Triomab antibodies have been generated that bind to tumor-associated antigens, e.g., EpCAM (catumaxomab), HER2/neu (ertumaxomab), CD20 (FBTA05), gangliosides GD2/GD3 (Ektomun), on appropriate tumor target cells associated with carcinomas, lymphomas or melanomas. Catumaxomab (Removab) was launched in Europe for treatment of malignant ascites in April 2009. Here, we report the structural and functional characterization of this product. Mass spectrometry revealed an intact mass of 150511 Dalton (Da) and 23717 Da, 24716 Da, 51957 Da and 52019 Da of the reduced and alkylated rat light chain, mouse light chain, rat heavy chain, mouse heavy chain chains, respectively. The observed masses were in agreement with the expected masses based on the amino acid sequence obtained from cDNA sequencing. The glycosylation profile was similar to other human IgG consisting of biantennary oligosaccharides with different numbers of terminal galactose. CD spectroscopy showed mainly beta-sheets secondary structure that is typical for IgG antibodies. Binding measurement revealed the unique trifunctional features of catumaxomab. Other analytical tools were used to evaluate characteristics of catumaxomab preparations, including the presence of isoforms and aggregates.
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The concept of using bispecific antibodies to retarget immune effector cells for cancer therapy was conceived more than 20 years ago. However, initial clinical studies were rather disappointing mainly due to low efficacy, severe adverse effects and immunogenicity of the bispecific antibodies. A deeper understanding of effector cell biology and especially developments in the field of antibody engineering has led to the generation of new classes of bispecific antibodies capable of circumventing many of these obstacles. Furthermore, new applications were established for bispecific antibodies, such as pre-targeting strategies in radioimmunotherapy or dual targeting approaches in order to improve binding, selectivity, and efficacy. This review summarizes recent progress in the development of bispecific antibodies and describes some new concepts developed for cancer immunotherapy.
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CD20 is an important target for the treatment of B-cell malignancies, including non-Hodgkin lymphoma as well as autoimmune disorders. B-cell depletion therapy using monoclonal antibodies against CD20, such as rituximab, has revolutionized the treatment of these disorders, greatly improving overall survival in patients. Here, we report the development of GA101 as the first Fc-engineered, type II humanized IgG1 antibody against CD20. Relative to rituximab, GA101 has increased direct and immune effector cell-mediated cytotoxicity and exhibits superior activity in cellular assays and whole blood B-cell depletion assays. In human lymphoma xenograft models, GA101 exhibits superior antitumor activity, resulting in the induction of complete tumor remission and increased overall survival. In nonhuman primates, GA101 demonstrates superior B cell-depleting activity in lymphoid tissue, including in lymph nodes and spleen. Taken together, these results provide compelling evidence for the development of GA101 as a promising new therapy for the treatment of B-cell disorders.
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Angiogenesis is required in normal physiological processes, but is also involved in tumor growth, progression and metastasis. Vascular endothelial growth factor (VEGF), a primary mediator of angiogenesis in normal physiology and in disease, and other VEGF family members and their receptors provide targets that have been explored extensively for cancer therapy. Small molecule inhibitors and antibody/protein-based strategies that target the VEGF pathway have been studied in multiple types of cancer. This review will focus on VEGF pathway targeting antibodies that are currently being evaluated in pre-clinical and clinical studies.
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Improved affinity for the neonatal Fc receptor (FcRn) is known to extend antibody half-life in vivo. However, this has never been linked with enhanced therapeutic efficacy. We tested whether antibodies with half-lives extended up to fivefold in human (h)FcRn transgenic mice and threefold in cynomolgus monkeys retain efficacy at longer dosing intervals. We observed that prolonged exposure due to FcRn-mediated enhancement of half-life improved antitumor activity of Fc-engineered antibodies in an hFcRn/Rag1(-/-) mouse model. This bridges the demand for dosing convenience with the clinical necessity of maintaining efficacy.
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Epidermal growth factor receptor (EGFR) is a validated therapeutic target in cancer and EGFR antagonists with greater effectiveness than existing clinical agents remain of interest. Here, we report a novel approach based on Sym004, a mixture of two anti-EGFR monoclonal antibodies directed against distinct nonoverlapping epitopes in EGFR extracellular domain III. Like anti-EGFR monoclonal antibodies in current clinical use, Sym004 inhibits cancer cell growth and survival by blocking ligand-binding receptor activation and phosphorylation and downstream receptor signaling. However, unlike the other antibodies, Sym004 induces rapid and efficient removal of the receptor from the cancer cell surface by triggering EGFR internalization and degradation. Compared with reference anti-EGFR monoclonal antibodies, Sym004 exhibited more pronounced growth inhibition in vitro and superior efficacy in vivo. Together, these findings illustrate a strategy to target EGFR more effectively than existing clinical antibodies.
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Purpose To evaluate the safety, maximum-tolerated dose (MTD), pharmacokinetics (PKs), pharmacodynamics, and preliminary anticancer activity of ramucirumab (IMC-1121B), a fully human immunoglobulin G 1 monoclonal antibody targeting the vascular endothelial growth factor receptor (VEGFR)-2. Patients and Methods Patients with advanced solid malignancies were treated once weekly with escalating doses of ramucirumab. Blood was sampled for PK studies throughout treatment. The effects of ramucirumab on circulating vascular endothelial growth factor-A (VEGF-A), soluble VEGFR-1 and VEGFR-2, tumor perfusion, and vascularity using dynamic contrast-enhanced magnetic resonance imaging were assessed. Results Thirty-seven patients were treated with 2 to 16 mg/kg of ramucirumab. After one patient each developed dose-limiting hypertension and deep venous thrombosis at 16 mg/kg, the next lower dose (13 mg/kg) was considered the MTD. Nausea, vomiting, headache, fatigue, and proteinuria were also noted. Four (15%) of 27 patients with measurable disease had a partial response (PR), and 11 (30%) of 37 patients had either a PR or stable disease lasting at least 6 months. PKs were characterized by dose-dependent elimination and nonlinear exposure consistent with saturable clearance. Mean trough concentrations exceeded biologically relevant target levels throughout treatment at all dose levels. Serum VEGF-A increased 1.5 to 3.5 times above pretreatment values and remained in this range throughout treatment at all dose levels. Tumor perfusion and vascularity decreased in 69% of evaluable patients. Conclusion Objective antitumor activity and antiangiogenic effects were observed over a wide range of dose levels, suggesting that ramucirumab may have a favorable therapeutic index in treating malignancies amenable to VEGFR-2 inhibition.
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Nimotuzumab is a humanized therapeutic monoclonal antibody against epidermal growth factor receptor (EGFR). Clinical trials are ongoing globally to evaluate nimotuzumab in different indications. Nimotuzumab has been granted approval for use in squamous cell carcinoma of head and neck (SCCHN), glioma and nasopharyngeal cancer in different countries. This review focuses on the unique functional characteristics of nimotuzumab. Also, it discusses the safety and efficacy data obtained from the Phase IIb clinical trial conducted in India in SCCHN. Post marketing surveillance data from Cuba for the use of nimotuzumab in pediatric and adult glioma is also discussed. Overall, nimotuzumab has immense therapeutic potential in cancers of epithelial origin.
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Ab-dependent cellular cytotoxicity (ADCC) is usually considered an important mechanism of action for immunotherapy with human IgG1 but not IgG2 Abs. The epidermal growth factor receptor (EGF-R) Ab panitumumab represents the only human IgG2 Ab approved for immunotherapy and inhibition of EGF-R signaling has been described as its principal mechanism of action. In this study, we investigated effector mechanisms of panitumumab compared with zalutumumab, an EGF-R Ab of the human IgG1 isotype. Notably, panitumumab was as effective as zalutumumab in recruiting ADCC by myeloid effector cells (i.e., neutrophils and monocytes) in contrast to NK cell-mediated ADCC, which was only induced by the IgG1 Ab. Neutrophil-mediated tumor cell killing could be stimulated by myeloid growth factors and was triggered via FcgammaRIIa. Panitumumab-mediated ADCC was significantly affected by the functional FcgammaRIIa-R131H polymorphism and was induced more effectively by neutrophils from FcgammaRIIa-131H homozygous donors than from -131R individuals. This polymorphism did not affect neutrophil ADCC induced by the IgG1 Ab zalutumumab. The in vivo activity of both Abs was assessed in two animal models: a high-dose model, in which signaling inhibition is a dominant mechanism of action, and a low-dose model, in which effector cell recruitment plays a prominent role. Zalutumumab was more effective than panitumumab in the high-dose model, reflecting its stronger ability to induce EGF-R downmodulation and growth inhibition. In the low-dose model, zalutumumab and panitumumab similarly prevented tumor growth. Thus, our results identify myeloid cell-mediated ADCC as a potent and additional mechanism of action for EGF-R-directed immunotherapy.
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The human anti-epidermal growth factor receptor (EGFR) monoclonal antibody, panitumumab, represents a significant advance in the treatment of colorectal cancer. The strategy to target this receptor is based on sound cancer biology demonstrating its essential role in colorectal carcinogenesis. Panitumumab, unlike its predecessor, cetuximab, is fully human and thus reduces the incidence of hypersensitivity reactions. But, in several clinical trials, unexpected toxicities have become more apparent, raising concerns of how readily panitumumab can succeed cetuximab. This paper reviews the development of this agent and the pivotal clinical trials that help our understanding of its optimal use in colorectal cancer treatment.
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Epidermal growth factor receptor (EGFR) and HER2 are cell surface receptor tyrosine kinases (TKs) that transduce growth signals through dimerization with HER family receptors. The heterodimerization of EGFR with HER2 induces a more potent activation of EGFR TK than does EGFR homodimerization. When tumor cells overexpress both EGFR and HER2, they exhibit aggressive tumor cell growth, owing to the increased potential for EGFR/HER2 heterodimerization and signaling. Gefitinib and erlotinib are EGFR TK inhibitors (EGFR TKIs) and have antitumor activity in 8-18% of patients with advanced non-small-cell lung cancer (NSCLC). Certain patient subsets are particularly responsive to EGFR TKIs. Analyses of biomarkers from patients in clinical studies of EGFR TKIs show correlations between objective tumor response and EGFR overexpression, as detected by immunohistochemistry and increased gene copy number measured by fluorescence in situ hybridization analysis. Furthermore, NSCLC tumors that overexpress both EGFR and HER2 are more sensitive to EGFR TKIs than are tumors that overexpress EGFR but are HER2 negative. Therefore, the measurement of EGFR and HER2 protein expression and the gene copy number in NSCLC tumors may have a prognostic value in NSCLC and a predictive value for identifying patients likely to benefit from an EGFR TKI. These considerations suggest that the simultaneous inhibition of EGFR and HER2 may warrant further study in patients with NSCLC.
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Catumaxomab, a monoclonal bispecific trifunctional antibody, was approved in the European Union in April 2009 for the intraperitoneal treatment of patients with malignant ascites. The marketing authorization holder Fresenius Biotech GmbH developed catumaxomab (Removab*) together with its partner TRION Pharma GmbH, Germany. It is the first substance worldwide with a regulatory label for the treatment of malignant ascites due to epithelial carcinomas. Since the peritoneum is of mesothelial origin and therefore lacks EpCAM expression, the intraperitoneal administration of catumaxomab is an attractive targeted immunotherapeutic approach. Catumaxomab is able to destroy EpCAM positive tumor cells in the peritoneal cavity known as the main cause of malignant ascites. In addition, catumaxomab is a potential therapeutic option for several primary tumors since the EpCAM molecule is expressed on the majority of epithelial carcinomas. This review focuses on the clinical development of catumaxomab and indicates future directions.
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The human vascular endothelial growth factor receptor-1 (VEGFR-1, or Flt-1) is widely expressed in normal and pathologic tissue and contributes to the pathogenesis of both neoplastic and inflammatory diseases. In human cancer, VEGFR-1 mediated signaling is responsible for both direct tumor activation and angiogenesis. VEGFR-1 mediated activation of nonmalignant supporting cells, particularly stromal, dendritic, hematopoietic cells, and macrophages, is also likely important for cancer pathogenesis. VEGFR-1 is also hypothesized to enable the development of cancer metastases by means of activation and premetastatic localization in distant organs of bone marrow-derived hematopoietic progenitor cells, which express VEGFR-1. IMC-18F1 is a fully human IgG1 antibody that binds to VEGFR-1 and has been associated with the inhibition of cancer growth in multiple in vitro and human tumor xenograft models. The preliminary results of phase 1 investigations have also indicated a favorable safety profile for IMC-18F1 at doses that confer antibody concentrations that are associated with relevant antitumor activity in preclinical models. Cancer 2010;116(4 suppl):1027–32. © 2010 American Cancer Society.
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Conventional anticancer therapeutics often suffer from lack of specificity, resulting in poor therapeutic indexes and substantial toxicities to normal healthy tissues. Monoclonal antibodies have demonstrated considerable utility in cancer medicine, but their curative potential is often limited. Antibody-drug conjugates represent an innovative therapeutic approach that combines the desirable properties of monoclonal antibodies, with the cell killing activity of cytotoxic drugs, reducing systemic toxicity and increasing the therapeutic benefit for patients. In this review, we outline prominent examples of early and recent antibody-drug conjugates, discussing drugs, linker chemistries and classes of targets for product development.
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Introduction: Targeted therapy against CD20 with the mAb rituximab has led to significant improvements in survival for patients with B-cell non-Hodgkin's lymphoma (NHL). Despite these improvements, many patients relapse and/or become refractory after rituximab-containing therapies and thus better therapies are required for NHL. Areas covered: Obinutuzumab is a novel, humanized, anti-CD20 mAb currently being investigated in Phase III studies in comparison to rituximab. An overview of obinutuzumab, its mechanisms of action and the results of pre-clinical and Phase I/II studies are presented. Expert opinion: Pre-clinical studies suggest that obinutuzumab is a more potent anti-CD20 mAb than Rituximab at inducing antibody-dependent cellular cytotoxicity (ADCC) and direct cell death (DCD). Obinutuzumab is safe and effective in CD20 + NHL and further study is warranted. Results of ongoing Phase III clinical trials comparing Obinutuzumab to Rituximab in different disease settings and with different chemotherapy regimens are eagerly awaited.
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AME-133v is a humanized monoclonal antibody engineered to have increased affinity to CD20 and mediate antibody-dependent cell-mediated cytotoxicity (ADCC) better than rituximab. Safety, pharmacokinetics, and efficacy were assessed in a phase 1/2 trial in patients with previously treated follicular lymphoma (FL). AME-133v was characterized in vitro by ADCC and cell binding assays. A phase 1 study was conducted in which 23 previously treated patients with FL were assigned sequentially to one of five dose-escalation cohorts of AME-133v at 2, 7.5, 30, 100, or 375 mg/m(2) weekly × 4 doses. AME-133v showed a 13- to 20-fold greater binding affinity for CD20 and was 5- to 7-fold more potent than rituximab in ADCC assays. Cell binding assays showed AME-133v and rituximab competed for an overlapping epitope on the CD20 antigen, and AME-133v inhibited binding of biotinylated rituximab to CD20 in a concentration-dependent manner. AME-133v was well tolerated by patients and common related adverse events included chills and fatigue. One patient experienced a dose-limiting toxicity of neutropenia. AME-133v showed nonlinear pharmocokinetics with properties similar to rituximab. Selective reduction of B cells during and after AME-133v treatment was shown by flow cytometry of peripheral blood. A partial or complete response was observed in 5 of 23 (22%) patients and the median progression-free survival was 25.4 weeks. AME-133v was safe and well tolerated at the doses tested. AME-133v showed encouraging results as an anti-CD20 therapy in heavily pretreated FL patients with the less favorable FcγRIIIa F-carrier genotype.
Article
MEHD7945A is a novel dual-action monoclonal antibody in which each of the two antigen-binding fragments is capable of binding to EGFR and HER3 with high affinity. It is being evaluated as a potential therapy for human cancer. The purpose of these studies was to characterize the pharmacokinetics (PK) of MEHD7945A in mouse and monkey and predict its human PK and efficacious dose. PK of MEHD7945A was determined in SCID beige mice and cynomolgus monkeys after administration of single intravenous doses. Human PK profiles were projected from monkey PK profiles using a species-invariant time method, and human population PK parameters were estimated using a nonlinear, two-compartment model comprising specific (target-mediated) and nonspecific clearance pathways. The antitumor efficacy in mice bearing human tumor xenografts was used in conjunction with human PK projections to estimate human efficacious doses. The total clearance of MEHD7945A decreased with increase in dose in both mouse and monkey. The nonspecific clearance in monkey was estimated to be 14 mL/day/kg. The predicted nonspecific clearance range in humans was 6-10 mL/day/kg. Doses of 8-12 mg/kg administered every 2 weeks in humans were predicted to achieve exposure of 300 day μg/mL per week to match the efficacious exposure observed in xenograft models. The PK of MEHD7945A was nonlinear in mouse and monkey in the dose range tested. The nonspecific clearance in monkey was approximately twofold higher than typical humanized IgG1 antibodies. The projected human efficacious dose and dose regimen appear to be achievable in patients.
Article
CD33, a 67-kDa glycoprotein expressed on the majority of myeloid leukemia cells as well as on normal myeloid and monocytic precursors, has been an attractive target for monoclonal antibody (mAb)-based therapy of acute myeloid leukemia (AML). Lintuzumab, an unconjugated, humanized anti-CD33 mAb, has modest single-agent activity against AML but failed to improve patient outcomes in two randomized trials when combined with conventional chemotherapy. Gemtuzumab ozogamicin, an anti-CD33 mAb conjugated to the antitumor antibiotic calicheamicin, improved survival in a subset of AML patients when combined with standard chemotherapy, but safety concerns led to US marketing withdrawal. The activity of these agents confirms that CD33 remains a viable therapeutic target for AML. Strategies to improve the results of mAb-based therapies for AML include antibody engineering to enhance effector function, use of alternative drugs and chemical linkers to develop safer and more effective drug conjugates, and radioimmunotherapeutic approaches.
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On 13 July 2011 the European Commission issued a marketing authorisation valid throughout the European Union (EU) for ipilimumab for the treatment of advanced (unresectable or metastatic) melanoma in adults who have received prior therapy. Ipilimumab is a monoclonal antibody that specifically blocks the inhibitory signal of cytotoxic T lymphocyte antigen 4 (CTLA-4), resulting in T cell activation, proliferation and lymphocyte infiltration into tumours, leading to tumour cell death. The recommended induction regimen of ipilimumab is 3mg/kg administered intravenously over a 90 min period every 3 weeks for a total of four doses. In a phase 3 trial in patients with advanced melanoma, median overall survival for ipilimumab was 10 months versus 6 months for gp100, an experimental melanoma vaccine (Hazard ratio (HR) 0.66; 95% confidence interval (CI): 0.51, 0.87; p = 0.0026). Ipilimumab was most commonly associated with adverse reactions resulting from increased or excessive immune activity. Most of these, including severe reactions, resolved following initiation of appropriate medical therapy or withdrawal of ipilimumab. The most common side-effects (affecting more than 10% of patients) were diarrhoea, rash, pruritus, fatigue, nausea, vomiting, decreased appetite and abdominal pain. The objective of this paper is to summarise the scientific review of the application leading to approval in the EU. The detailed scientific assessment report and product information, including the summary of product characteristics (SmPC), are available on the European Medicines Agency (EMA) website (www.ema.europa.eu).