[Show abstract][Hide abstract] ABSTRACT: The capture and activation of individual T cells on functionalised surfaces enables real-time analyses of the magnitude and rhythm of intracellular calcium release. Application of Haarlet transformations generate a calcium flux 'threshold', with the frequency of the 'threshold crossings' correlating with the strength of the original T cell stimulus. These findings represent a new method to evaluate graduations in T cell activation in real time, and at a single-cell level.
[Show abstract][Hide abstract] ABSTRACT: Cancer immunotherapy has long been used in the treatment of metastatic melanoma, and an anti-CTLA-4 monoclonal antibody treatment has recently been approved by the US Food and Drug Administration. Targeted therapies such as small molecule kinase inhibitors targeting deregulated mitogen-activated protein kinase (MAPK) signaling have markedly improved melanoma control in up to 50% of metastatic disease patients and have likewise been recently approved. Combination therapies for melanoma have been proposed as a way to exploit the high-level but short-term responses associated with kinase inhibitor therapies and the low-level but longer-term responses associated with immunotherapy. Cancer immunotherapy now includes adoptive transfer of autologous tumor-specific chimeric antigen receptor (CAR) T cells and this mode of therapy is a candidate for combination with small molecule drugs. This paper describes CART cells that target GD2-expressing melanoma cells and investigates the effects of approved MAPK pathway-targeted therapies for melanoma [vemurafenib (Vem), dabrafenib (Dab), and trametinib (Tram)] on the viability, activation, proliferation, and cytotoxic T lymphocyte activity of these CAR T cells, as well as on normal peripheral blood mononuclear cells. We report that, although all these drugs lead to inhibition of stimulated T cells at high concentrations in vitro, only Vem inhibited T cells at concentrations equivalent to reported plasma concentrations in treated patients. Although the combination of Dab and Tram also resulted in inhibition of T-cell effector functions at some therapeutic concentrations, Dab itself had little adverse effect on CAR T-cell function. These findings may have implications for novel therapeutic combinations of adoptive CAR T-cell immunotherapy and MAPK pathway inhibitors.
[Show abstract][Hide abstract] ABSTRACT: Immune modulation has become a central element in many cancer treatments, and T cells genetically engineered to express chimeric antigen receptors (CAR) may provide a new approach to cancer immunotherapy. Autologous CAR T cells that have been re-directed toward tumor-associated antigens (TAA) have shown promising results in phase 1 clinical trials, with some patients undergoing complete tumor regression. However, this T-cell therapy must carefully balance effective T-cell activation, to ensure antitumor activity, with the potential for uncontrolled activation that may produce immunopathology. An inducible Caspase 9 (iCasp9) "safety switch" offers a solution that allows for the removal of inappropriately activated CAR T cells. The induction of iCasp9 depends on the administration of the small molecule dimerizer drug AP1903 and dimerization results in rapid induction of apoptosis in transduced cells, preferentially killing activated cells expressing high levels of transgene. The iCasp9 gene has been incorporated into vectors for use in preclinical studies and demonstrates effective and reliable suicide gene activity in phase 1 clinical trials. A third-generation CAR incorporating iCasp9 re-directs T cells toward the GD2 TAA. GD2 is over-expressed in melanoma and other malignancies of neural crest origin and the safety and activity of these GD2-iCAR T cells will be investigated in CARPETS and other actively recruiting phase 1 trials.
Frontiers in Pharmacology 10/2014; 5:235. DOI:10.3389/fphar.2014.00235 · 3.80 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Resistance to conventional cancer treatments is a major problem associated with solid tumours. Tumour hypoxia is associated with a poor prognosis and with poor treatment outcomes; therefore, there is a need for treatments that can kill hypoxic tumour cells. One potential option is targeted α-radioimmunotherapy, as α-particles can directly kill hypoxic tumour cells. The murine monoclonal antibody DAB4 (APOMAB), which binds dead tumour cells after DNA-damaging treatment, was conjugated and radiolabelled with the α-particle-emitting radionuclide thorium-227 (Th). Mice bearing Lewis lung tumours were administered Th-DAB4 alone or after chemotherapy and the tissue biodistribution of the radioimmunoconjugate was examined, as was the effect of these treatments on tumour growth and survival. Th-DAB4 accumulated in the tumour particularly after chemotherapy, whereas the distribution in healthy tissues did not change. Th-DAB4 as a monotherapy increased survival, with more pronounced responses observed when given after chemotherapy. We have shown that targeted α-therapy of necrotic tumour cells with Th-DAB4 had significant and surprising antitumour activity as it would occur only through a cross-fire effect.
Nuclear Medicine Communications 09/2014; 35(12). DOI:10.1097/MNM.0000000000000199 · 1.37 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Radio-resistant hypoxic tumor cells are significant contributors to the locoregional recurrences and distant metastases that mark failure of radiotherapy. Due to restricted tissue oxygenation, chronically hypoxic tumor cells frequently become necrotic and thus there is often an association between chronically hypoxic and necrotic tumor regions. This simulation study is the first in a series to determine the feasibility of hypoxic cell killing after first targeting adjacent areas of necrosis with either an α- or β-emitting radioimmunoconjugate.
[Show abstract][Hide abstract] ABSTRACT: Over the last decade, the significance of the homeostatic CC chemokine receptor-7 and its ligands CC chemokine ligand-19 (CCL19) and CCL21, in various types of cancer, particularly mammary carcinoma, has been highlighted. The chemokine receptor CCX-CKR is a high-affinity receptor for these chemokine ligands but rather than inducing classical downstream signalling events promoting migration, it instead sequesters and targets its ligands for degradation, and appears to function as a regulator of the bioavailability of these chemokines in vivo. Therefore, in this study, we tested the hypothesis that local regulation of chemokine levels by CCX-CKR expressed on tumours alters tumour growth and metastasis in vivo. Expression of CCX-CKR on 4T1.2 mouse mammary carcinoma cells inhibited orthotopic tumour growth. However, this effect could not be correlated with chemokine scavenging in vivo and was not mediated by host adaptive immunity. Conversely, expression of CCX-CKR on 4T1.2 cells resulted in enhanced spontaneous metastasis and haematogenous metastasis in vivo. In vitro characterisation of the tumourigenicity of CCX-CKR-expressing 4T1.2 cells suggested accelerated epithelial-mesenchymal transition (EMT) revealed by their more invasive and motile character, lower adherence to the extracellular matrix and to each other, and greater resistance to anoikis. Further analysis of CCX-CKR-expressing 4T1.2 cells also revealed that transforming growth factor (TGF)-β1 expression was increased both at mRNA and protein levels leading to enhanced autocrine phosphorylation of Smad 2/3 in these cells. Together, our data show a novel function for the chemokine receptor CCX-CKR as a regulator of TGF-β1 expression and the EMT in breast cancer cells.Immunology and Cell Biology advance online publication, 15 July 2014; doi:10.1038/icb.2014.58.
[Show abstract][Hide abstract] ABSTRACT: Purpose: Dabrafenib is a selective, potent ATP-competitive inhibitor of the BRAFV600-mutant kinase that has demonstrated efficacy in clinical trials. We report the rationale for dose selection in the first-in-human study of dabrafenib, including pharmacokinetics, tissue pharmacodynamics, 18F-labelled fluorodeoxyglucose-positron emission tomography (FDG-PET) pharmacodynamics, and dose-response relationship. Methods: Dabrafenib was administered orally once, twice (BID), or three times (TID) daily. Selected dose cohorts were expanded to collect adequate data on safety, pharmacokinetics, or pharmacodynamics. A recommended phase 2 dose (RP2D) was chosen based on safety, pharmacokinetic, pharmacodynamic, and response data. Results: 184 patients were enrolled and treated with doses ranging from 12mg once daily to 300mg BID in 10 cohorts. Pharmacokinetic assessment of dabrafenib demonstrated a less-than-dose-proportional increase in exposure after repeat dosing above 150mg BID. Similar to parent drug concentrations, exposure for all metabolites demonstrated less-than-dose-proportional increases. Predicted target inhibition of pERK (>80%) was achieved at 150mg BID, with a similar magnitude of inhibition at higher doses in BRAFV600mutation melanoma biopsy samples. Although there was large variability between patients, FDG uptake decreased with higher daily doses in patients with BRAFV600 mutation-positive melanoma. A favorable activity and tolerability profile was demonstrated at 150mg BID. There was no improvement with TID dosing compared with BID dosing, based on FDG-PET and tumor response analyses in melanoma patients. Conclusion: The RP2D of dabrafenib was determined to be 150mg BID after considering multiple factors, including pharmacokinetics, tissue pharmacodynamics, FDG-PET pharmacodynamics, and the dose-response relationship. A maximum tolerated dose for dabrafenib was not determined.
Clinical Cancer Research 06/2014; 20(17). DOI:10.1158/1078-0432.CCR-14-0887 · 8.19 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Purpose: To develop effective combination therapy against pancreatic ductal adenocarcinoma (PDAC) with a combination of chemotherapy, CHK1 inhibition, and EGFR-targeted radioimmunotherapy. Experimental Design: Maximum tolerated doses were determined for the combination of gemcitabine, the CHK1 inhibitor PF-477736, and Lutetium-177 (Lu-177)-labeled anti-EGFR antibody. This triple combination therapy was investigated using PDAC models from well-established cell lines, recently established patient-derived cell lines, and fresh patient-derived xenografts. Tumors were investigated for the accumulation of Lu-177-anti-EGFR antibody, survival of tumor-initiating cells, induction of DNA damage, cell death, and tumor tissue degeneration. Results: The combination of gemcitabine and CHK1 inhibitor PF-477736 with Lu-177-anti-EGFR antibody was tolerated in mice. This triplet was effective in established tumors and prevented the recurrence of PDAC in four cell line-derived and one patient-derived xenograft model. This exquisite response was associated with the loss of tumor-initiating cells as measured by flow cytometric analysis and secondary implantation of tumors from treated mice into treatment-naive mice. Extensive DNA damage, apoptosis, and tumor degeneration were detected in the patient-derived xenograft. Mechanistically, we observed CDC25A stabilization as a result of CHK1 inhibition with consequent inhibition of gemcitabine-induced S-phase arrest as well as a decrease in canonical (ERK1/2 phosphorylation) and noncanonical EGFR signaling (RAD51 degradation) as a result of EGFR inhibition. Conclusions: Our study developed an effective combination therapy against PDAC that has potential in the treatment of PDAC. (C) 2014 AACR.
Clinical Cancer Research 05/2014; 20(12). DOI:10.1158/1078-0432.CCR-14-0048 · 8.19 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Metastatic melanoma remains one of the major causes of death related to skin cancers and has been resistant to traditional anticancer therapies. The clinical development of vemurafenib in the treatment of metastatic melanoma with the V600 mutation of the BRAF gene has provided meaningful improvements in the overall survival and progression-free survival of metastatic melanoma patients. However, significant side effects have been noted with this therapy, in particular cutaneous adverse events (AEs) such as rashes, squamous cell carcinoma and severe photosensitivity to UVA light among others. With an emphasis on the Australian perspective, this review provides an overview of the clinical development of vemurafenib, its attendant dose-limiting toxicities and other AEs, recommendations for safety monitoring, supportive treatments of AEs and dose modifications, with the aim of maximizing the chances of continuing beneficial treatment.
[Show abstract][Hide abstract] ABSTRACT: Evaluation of: Younes A, Connors JM, Park SI et al. Brentuximab vedotin combined with ABVD or AVD for patients with newly diagnosed Hodgkin's lymphoma: a Phase 1, open-label, dose-escalation study. Lancet Oncol. 14(13), 1348-1356 (2013). With exceptionally high response rates, the CD30-directed antibody-drug conjugate brentuximab vedotin (BV) was US FDA approved for treatment of patients with relapsed/refractory Hodgkin lymphoma (HL). Now in Phase I clinical trial, it has been shown that combining BV with multiagent chemotherapy (excluding bleomycin) as first-line treatment in HL patients with high-risk disease is feasible. Complete response rates were over 90% and toxicity was manageable. Given that the malignant cell population comprises a minority of HL lesions, and that BV releases a diffusible cytotoxin via a cathepsin B-cleavable linker, we argue that a significant proportion of the antitumor activity of BV can be attributed to bystander cytotoxicity in addition to direct killing of CD30-expressing malignant cells.
[Show abstract][Hide abstract] ABSTRACT: Early identification of tumor responses to treatment is crucial for devising more effective and safer cancer treatments. No widely applicable, noninvasive method currently exists for specifically detecting tumor cell death after cytotoxic treatment and thus for predicting treatment outcomes.
We have further characterized the targeting of the murine monoclonal antibody DAB4 specifically to dead tumor cells in vitro, in vivo, and in clinical samples. We found that sustained DAB4 binding to treated cells was closely associated with markers of intrinsic apoptosis and DNA double-strand break formation. In a competition binding assay, DAB4 bound EL4 murine thymic lymphoma cells in preference to the normal counterpart of murine thymocytes. Defective in vivo clearance of apoptotic cells augmented in vivo accumulation of DAB4 in tumors particularly after chemotherapy but was unchanged in normal tissues. Tumor targeting of DAB4 was selective for syngeneic murine tumors and for human tumor xenografts of prostate cancer (PC-3) and pancreatic cancer (Panc-1) before and more so after chemotherapy. Furthermore, DAB4 was shown to bind to dead primary acute lymphoblastic leukemic blasts cultured with cytotoxic drugs and dead epithelial cancer cells isolated from peripheral blood of small cell lung carcinoma patients given chemotherapy.
Collectively, these results further demonstrate the selectivity of DAB4 for chemotherapy-induced dead tumor cells. This postchemotherapy selectivity is related to a relative increase in the availability of DAB4-binding targets in tumor tissue rather than in normal tissues. The in vitro findings were translated in vivo to human xenograft models and to ex vivo analyses of clinical samples, providing further evidence of the potential of DAB4 as a marker of tumor cell death after DNA-damaging cytotoxic treatment that could be harnessed as a predictive marker of treatment responses.
Journal of Nuclear Medicine 03/2014; 55(5). DOI:10.2967/jnumed.113.130559 · 5.56 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The orally available BRAF kinase inhibitor vemurafenib, compared with dacarbazine, shows improved response rates, progression-free survival (PFS), and overall survival in patients with metastatic melanoma that has a BRAF(V600) mutation. We assessed vemurafenib in patients with advanced metastatic melanoma with BRAF(V600) mutations who had few treatment options.
In an open-label, multicentre study, patients with untreated or previously treated melanoma and a BRAF(V600) mutation received oral vemurafenib 960 mg twice a day. The primary endpoint was safety. All analyses were done on the safety population, which included all patients who received at least one dose of vemurafenib. This report is the third interim analysis of this study. This study is registered with ClinicalTrials.gov, number NCT01307397.
Between March 1, 2011, and Jan 31, 2013, 3226 patients were enrolled in 44 countries. 3222 patients received at least one dose of vemurafenib (safety population). At data cutoff, 868 (27%) patients were on study treatment and 2354 (73%) had withdrawn, mainly because of disease progression. Common adverse events of all grades included rash (1592 [49%]), arthralgia (1259 [39%]), fatigue (1093 [34%]), photosensitivity reaction (994 [31%]), alopecia (826 [26%]), and nausea (628 [19%]). 1480 (46%) patients reported grade 3 or 4 adverse events, including cutaneous squamous cell carcinoma (389 [12%]), rash (155 [5%]), liver function abnormalities (165 [5%]), arthralgia (106 [3%]), and fatigue (93 [3%]). Grade 3 and 4 adverse events were reported more frequently in patients aged 75 years and older (n=257; 152 [59%, 95% CI 53-65] and ten [4%, 2-7], respectively) than in those younger than 75 years (n=2965; 1286 [43%, 42-45] and 82 [3%, 2-3], respectively).
Vemurafenib safety in this diverse population of patients with BRAF(V600) mutated metastatic melanoma, who are more representative of routine clinical practice, was consistent with the safety profile shown in the pivotal trials of this drug.
F Hoffmann-La Roche.
The Lancet Oncology 02/2014; 15(4). DOI:10.1016/S1470-2045(14)70051-8 · 24.73 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The lupus-associated (La)-specific murine monoclonal antibody DAB4 (APOMAB(R)) specifically binds dead cancer cells. Using DAB4, we examined La expression in human lung cancer samples to assess its suitability as a cancer-selective therapeutic target. We evaluated the safety and effectiveness of radioimmunotherapy (RIT) using DAB4 radiolabeled with Lutetium-177 (177Lu) in the murine Lewis Lung (LL2) carcinoma model, and determined whether combining RIT with DNA-damaging cisplatin-based chemotherapy, a PARP inhibitor (PARPi), or both alters treatment responses.
The expression of La mRNA in human lung cancer samples was analysed using the online database Oncomine, and the protein expression of La was examined using a TissueFocus Cancer Survey Tissue Microarray. The binding of DAB4 to cisplatin-treated LL2 cells was assessed in vitro. LL2 tumour-bearing mice were administered escalating doses of 177Lu-DAB4 alone or in combination with chemotherapy, and tumour growth and survival measured. Biodistribution analysis was used to determine tissue uptake of 177Lu-DAB4 or its isotype control (177Lu-Sal5), when delivered alone or after chemotherapy. PARPi (rucaparib; AG-014699) was combined with chemotherapy and the effects of combined treatment on tumour growth, tumour cell DNA damage and death, and intratumoural DAB4 binding were also analysed. The effect of the triple combination of PARPi, chemotherapy and 177Lu- DAB4 on tumour growth and survival of LL2 tumour-bearing mice was tested.
La was over-expressed at both mRNA and protein levels in surgical specimens of human lung cancer and the over-expression of La mRNA conferred a poorer prognosis. DAB4 bound specifically to cisplatin-induced dead LL2 cells in vitro. An anti-tumour dose response was observed when escalating doses of 177Lu-DAB4 were delivered in vivo, with supra-additive responses observed when chemotherapy was combined with 177Lu-DAB4. Combining PARPi with chemotherapy was more effective than chemotherapy alone with increased tumour cell DNA damage and death, and intratumoural DAB4 binding. The combination of PARPi, chemotherapy and 177Lu-DAB4 was well-tolerated and maximised tumour growth delay.
The La antigen represents a dead cancer cell-specific target in lung cancer, and DAB4 specifically targeted tumour tissue in vivo, particularly after chemotherapy. Tumour uptake of DAB4 increased further after the combination of PARPi and chemotherapy, which generated new dead tumour cell-binding targets. Consequently, combining 177Lu-DAB4 with PARPi and chemotherapy produced the greatest anti-tumour response. Therefore, the triple combination of PARPi, chemotherapy and RIT may have broad clinical utility.
[Show abstract][Hide abstract] ABSTRACT: Nutlin-3a is a small molecule antagonist of p53/MDM2 that is being explored as a treatment for sarcoma. In this study, we examined the molecular mechanisms underlying the sensitivity of sarcomas to Nutlin-3a. In an ex vivo tissue explant system, we found that TP53 pathway alterations (TP53 status, MDM2/MDM4 genomic amplification/mRNA overexpression, MDM2 SNP309, and TP53 SNP72) didn't confer apoptotic or cytostatic responses in sarcoma tissue biopsies (n=24). Unexpectedly, MDM2 status didn't predict Nutlin-3a sensitivity. RNA sequencing revealed that the global transcriptomic profiles of these sarcomas provided a more robust prediction of apoptotic responses to Nutlin-3a. Expression profiling revealed a subset of TP53 target genes which were transactivated specifically in sarcomas that were highly sensitive to Nutlin-3a. Of these target genes, the GADD45A promoter region was shown to be hypermethylated in 82% of wild-type TP53 sarcomas that didn't respond to Nutlin-3a, thereby providing mechanistic insight into the innate ability of sarcomas to resist apoptotic death following Nutlin-3a treatment. Collectively, our findings argue that the existing benchmark biomarker for MDM2 antagonist efficacy (MDM2 amplification) should not be used to predict outcome, but rather global gene expression profiles and epigenetic status of sarcomas dictate their sensitivity to p53/MDM2 antagonists.
Cancer Research 12/2013; 74(3). DOI:10.1158/0008-5472.CAN-13-2424 · 9.28 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: It is uncertain whether survival increases from melanoma recorded by some population registries include a treatment effect. The US Surveillance, Epidemiology and End Results (SEER) programme has good data quality control, large numbers of cases enabling high statistical precision and summary stage plus thickness, which we consider to be a best-case population registry scenario to investigate potential for a treatment effect. We have investigated SEER data to indicate whether survivals increases are fully attributable to earlier diagnosis and other non-treatment factors.
Through relative survival regression, the effects of diagnostic period on 5-year excess mortality were investigated, adjusting for socio-demographic factors, lesion sub-site, histology, thickness and stage at diagnosis in 1990-2009 (n = 99 690 cases).
The reduction in excess mortality (95% confidence interval) between 1990-1999 and 2000-2009 was 31 (20-41)% for localised melanoma, 18 (12-22)% for regional melanoma and 3 (-5-10)% for melanomas with distant spread. Younger age was predictive of a greater percentage reduction. Treatment benefits are inferred from the higher survivals in 2000-2009 but uncertainty remains due to incomplete data to adjust for non-treatment factors and a lack of treatment data.
Registries should use new information systems to collect more complete data on stage, other prognostic indicators, co-morbidities and treatment, to provide more definitive and detailed information on population effects of cancer control.
Journal of Evaluation in Clinical Practice 09/2013; DOI:10.1111/jep.12081 · 1.58 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Passive immunotherapies utilising polyclonal antibodies could have a valuable role in preventing and treating infectious diseases such as influenza, particularly in pandemic situations but also in immunocompromised populations such as the elderly, the chronically immunosuppressed, pregnant women, infants and those with chronic diseases. The aim of this study was to optimise current methods used to generate ovine polyclonal antibodies. Polyclonal antibodies to baculovirus-expressed recombinant influenza haemagglutinin from A/Puerto Rico/8/1934 H1N1 (PR8) were elicited in sheep using various immunisation regimens designed to investigate the priming immunisation route, adjuvant formulation, sheep age, and antigen dose, and to empirically ascertain which combination maximised antibody output. The novel adjuvant CoVaccine HTâ„¢ was compared to Freundâ€™s adjuvant which is currently the adjuvant of choice for commercial production of ovine polyclonal Fab therapies. CoVaccine HTâ„¢ induced significantly higher titres of functional ovine anti-haemagglutinin IgG than Freundâ€™s adjuvant but with fewer side effects, including reduced site reactions. Polyclonal hyperimmune sheep sera effectively neutralised influenza virus in vitro and, when given before or after influenza virus challenge, prevented the death of infected mice. Neither the age of the sheep nor the route of antigen administration appeared to influence antibody titre. Moreover, reducing the administrated dose of haemagglutinin antigen minimally affected antibody titre. Together, these results suggest a cost effective way of producing high and sustained yields of functional ovine polyclonal antibodies specifically for the prevention and treatment of globally significant diseases.
PLoS ONE 07/2013; 8(7-7):e68895. DOI:10.1371/journal.pone.0068895 · 3.23 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Dabrafenib is a selective inhibitor of V600-mutant BRAF kinase, which recently demonstrated improved progression free survival (PFS) as compared with dacarbazine, in metastatic melanoma patients. The current study examined potential genetic markers associated with response and PFS in the phase I study of dabrafenib.
Baseline (pre-treatment or archival) melanoma samples were evaluated in 41 patients using a custom genotyping melanoma-specific assay, sequencing of PTEN, and copy number analysis using multiplex ligation amplification and array based comparative genomic hybridization. Nine patients had on-treatment and/or progression samples available.
All baseline patient samples had BRAFV600E/K confirmed. Baseline PTEN loss/mutation was not associated with best overall response (BOR) to dabrafenib, but it showed a trend for shorter median progression free survival (PFS) (18.3 [95% confidence interval (CI) 9.1-24.3] vs. 32.1 weeks [95% CI 24.1-33], p=0.059). Higher copy number of CCND1 (p=0.009) and lower copy number of CDKN2A (p=0.012) at baseline were significantly associated with decreased PFS. Although no melanomas had high level amplification of BRAF, the two patients with progressive disease as their best response had BRAF copy gain in their tumors.
Copy number changes in CDKN2A, CCND1, and mutation/copy number changes in PTEN correlated with the duration of PFS in patients treated with dabrafenib. The results suggest that these markers should be considered in the design and interpretation of future trials with selective BRAF inhibitors in advanced melanoma patients.
Clinical Cancer Research 07/2013; 19(17). DOI:10.1158/1078-0432.CCR-13-0827 · 8.19 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The present study evaluated the efficacy of drozitumab, a human monoclonal agonistic antibody directed against death receptor 5 (DR5), as a new therapeutic avenue for the targeted treatment of bone and soft-tissue sarcomas. The antitumour activity of drozitumab as a monotherapy or in combination with Nutlin-3a was evaluated in a panel of sarcoma cell lines in vitro and human sarcoma patient samples ex vivo. Knockdown experiments were used to investigate the central role of p53 as a regulator of drozitumab cytotoxicity. Pre-activation of the p53 pathway through Nutlin-3a upregulated DR5, subsequently sensitising sarcoma cell lines and human sarcoma specimens to the pro-apoptotic effects of drozitumab. Silencing of p53 strongly decreased DR5 mRNA expression resulting in abrogation of drozitumab-induced apoptosis. Our study provides the first pre-clinical evaluation of combination therapy using p53-activating agents with drozitumab to further sensitise sarcomas to the cytotoxic effects of DR5 antibody therapy.