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Laura A Vitale,
Li-Zhen He,
Lawrence J Thomas,
Jennifer Widger,
Jeffrey Weidlick,
Andrea Crocker,
Thomas O'Neill,
James Storey,
Martin J Glennie,
Deanna M Grote,
Stephen M Ansell,
Henry Marsh,
Tibor Keler
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ABSTRACT: The TNF receptor superfamily member CD27 is best known for its important role in T-cell immunity but is also recognized as a cell-surface marker on a number of B- and T-cell malignancies. In this article, we describe a novel human monoclonal antibody (mAb) specific for CD27 with properties that suggest a potential utility against malignancies that express CD27.
The fully human mAb 1F5 was generated using human Ig transgenic mice and characterized by analytical and functional assays in vitro. Severe combined immunodeficient (SCID) mice inoculated with human CD27-expressing lymphoma cells were administered 1F5 to investigate direct antitumor effects. A pilot study of 1F5 was conducted in non-human primates to assess toxicity.
1F5 binds with high affinity and specificity to human and macaque CD27 and competes with ligand binding. 1F5 activates T cells only in combination with T-cell receptor stimulation and does not induce proliferation of primary CD27-expressing tumor cells. 1F5 significantly enhanced the survival of SCID mice bearing Raji or Daudi tumors, which may be mediated through direct effector mechanisms such as antibody-dependent cellular cytotoxicity. Importantly, administration of up to 10 mg/kg of 1F5 to cynomolgus monkeys was well tolerated without evidence of significant toxicity or depletion of circulating lymphocytes.
Collectively, the data suggest that the human mAb 1F5, which has recently entered clinical development under the name CDX-1127, may provide direct antitumor activity against CD27-expressing lymphoma or leukemia, independent of its potential to enhance immunity through its agonistic properties.
Clinical Cancer Research 05/2012; 18(14):3812-21. · 7.74 Impact Factor
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Michael A Morse,
Robert Chapman,
John Powderly,
Kimberly Blackwell,
Tibor Keler,
Jennifer Green,
Renee Riggs,
Li-Zhen He,
Venky Ramakrishna, Laura Vitale,
Biwei Zhao,
Stephen A Butler,
Amy Hobeika,
Takuya Osada,
Thomas Davis,
Timothy Clay,
H Kim Lyerly
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ABSTRACT: The use of tumor-derived proteins as cancer vaccines is complicated by tolerance to these self-antigens. Tolerance may be broken by immunization with activated, autologous, ex vivo generated and antigen-loaded, antigen-presenting cells (APC); however, targeting tumor antigen directly to APC in vivo would be a less complicated strategy. We wished to test whether targeted delivery of an otherwise poorly immunogenic, soluble antigen to APC through their mannose receptors (MR) would induce clinically relevant immunity.
Two phase I studies were conducted with CDX-1307, a vaccine composed of human chorionic gonadotropin beta-chain (hCG-β) fused to an MR-specific monoclonal antibody, administered either locally (intradermally) or systemically (intravenously) in patients with advanced epithelial malignancies. An initial dose escalation of single-agent CDX-1307 was followed by additional cohorts of CDX-1307 combined with granulocyte-macrophage colony-stimulating factor (GM-CSF) and the Toll-like receptor (TLR) 3 agonist polyinosinic-polycytidylic acid (poly-ICLC) and TLR7/8 agonist resiquimod to activate the APC.
CDX-1307 induced consistent humoral and T-cell responses to hCG-β when coadministered with TLR agonists. Greater immune responses and clinical benefit, including the longest duration of stable disease, were observed with immunization combined with local TLR agonists. Immune responses were induced equally efficiently in patients with elevated and nonelevated levels of serum hCG-β. Antibodies within the serum of vaccinated participants had tumor suppressive function in vitro. Toxicity consisted chiefly of mild injection site reactions.
APC targeting and activation induce adaptive immunity against poorly immunogenic self-antigens which has implications for enhancing the efficacy of cancer immunotherapy.
Clinical Cancer Research 06/2011; 17(14):4844-53. · 7.74 Impact Factor
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Takemasa Tsuji,
Junko Matsuzaki,
Marcus P Kelly,
Venky Ramakrishna, Laura Vitale,
Li-Zhen He,
Tibor Keler,
Kunle Odunsi,
Lloyd J Old,
Gerd Ritter,
Sacha Gnjatic
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ABSTRACT: Immunization of cancer patients with vaccines containing full-length tumor Ags aims to elicit specific Abs and both CD4(+) and CD8(+) T cells. Vaccination with protein Ags, however, often elicits only CD4(+) T cell responses without inducing Ag-specific CD8(+) T cells, as exogenous protein is primarily presented to CD4(+) T cells. Recent data revealed that Ab-mediated targeting of protein Ags to cell surface receptors on dendritic cells could enhance the induction of both CD4(+) and CD8(+) T cells. We investigated in this study if these observations were applicable to NY-ESO-1, a cancer-testis Ag widely used in clinical cancer vaccine trials. We generated two novel targeting proteins consisting of the full-length NY-ESO-1 fused to the C terminus of two human mAbs against the human mannose receptor and DEC-205, both internalizing molecules expressed on APC. These targeting proteins were evaluated for their ability to activate NY-ESO-1-specific human CD4(+) and CD8(+) T cells in vitro. Both targeted NY-ESO-1 proteins rapidly bound to their respective targets on APC. Whereas nontargeted and Ab-targeted NY-ESO-1 proteins similarly activated CD4(+) T cells, cross-presentation to CD8(+) T cells was only efficiently induced by targeted NY-ESO-1. In addition, both mannose receptor and DEC-205 targeting elicited specific CD4(+) and CD8(+) T cells from PBLs of cancer patients. Receptor-specific delivery of NY-ESO-1 to APC appears to be a promising vaccination strategy to efficiently generate integrated and broad Ag-specific immune responses against NY-ESO-1 in cancer patients.
The Journal of Immunology 01/2011; 186(2):1218-27. · 5.79 Impact Factor
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Cheolho Cheong,
Jae-Hoon Choi, Laura Vitale,
Li-Zhen He,
Christine Trumpfheller,
Leonia Bozzacco,
Yoonkyung Do,
Godwin Nchinda,
Sung Ho Park,
Durga Bhavani Dandamudi,
Elina Shrestha,
Maggi Pack,
Han-Woong Lee,
Tibor Keler,
Ralph M Steinman,
Chae Gyu Park
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ABSTRACT: Protein vaccines for T-cell immunity are not being prioritized because of poor immunogenicity. To overcome this hurdle, proteins are being targeted to maturing dendritic cells (DCs) within monoclonal antibodies (mAbs) to DC receptors. To extend the concept to humans, we immunized human immunoglobulin-expressing mice with human DEC205 (hDEC205) extracellular domain. 3D6 and 3G9 mAbs were selected for high-affinity binding to hDEC205. In addition, CD11c promoter hDEC205 transgenic mice were generated, and 3G9 was selectively targeted to DCs in these animals. When mAb heavy chain was engineered to express HIV Gag p24, the fusion mAb induced interferon-γ- and interleukin-2-producing CD4(+) T cells in hDEC205 transgenic mice, if polynocinic polycytidylic acid was coadministered as an adjuvant. The T-cell response was broad, recognizing at least 3 Gag peptides, and high titers of anti-human immunoglobulin G antibody were made. Anti-hDEC205 also improved the cross-presentation of Gag to primed CD8(+) T cells from HIV-infected individuals. In all tests, 3D6 and 3G9 targeting greatly enhanced immunization relative to nonbinding control mAb. These results provide preclinical evidence that in vivo hDEC205 targeting increases the efficiency with which proteins elicit specific immunity, setting the stage for proof-of-concept studies of these new protein vaccines in human subjects.
Blood 11/2010; 116(19):3828-38. · 9.90 Impact Factor
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ABSTRACT: This study is an exploration of engagement in outpatient medical care, medication utilization, and barriers to treatment utilization among 24 predominantly low-income, ethnic minority adults who were admitted to an urban hospital for HIV-related illnesses. A semi-structured interview was administered during the sample's hospital stay to explore patterns of service use and identify barriers to care. The majority of the sample was connected to an outpatient provider and satisfied with the care they received; however, most missed treatment appointments and skipped medication dosages. Health and treatment-related barriers, competing demands, and co-occurring mental health symptoms and illicit substance use were identified as barriers to care. Multiple obstacles indigenous to the individual, their treatment, and the environment prevented consistent treatment use among an economically disadvantaged ethnic minority sample: Implications and future directions in engaging vulnerable populations into health care for HIV are discussed.
Social Work in Health Care 11/2010; 49(10):934-45. · 0.62 Impact Factor
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ABSTRACT: The neutralizing antibody response to the protective antigen (PA) component of anthrax toxin elicited by approved anthrax vaccines is an accepted correlate for vaccine-mediated protection against anthrax. We reasoned that a human anti-PA monoclonal antibody (MAb) selected on the basis of superior toxin neutralization activity might provide potent protection against anthrax. The fully human MAb (also referred to as MDX-1303 or Valortim) was chosen from a large panel of anti-PA human MAbs generated using transgenic mice immunized with recombinant PA solely on the basis of in vitro anthrax toxin neutralization. This MAb was effective in prophylactic and postsymptomatic treatment of rabbits exposed to aerosolized anthrax spores, and a single intramuscular injection of 1 mg/kg of body weight fully protected cynomolgus monkeys challenged with aerosolized anthrax spores. Importantly, MAb 1303 defines a novel neutralizing epitope that requires Fc receptor engagement for maximal activity. F(ab')2 fragments of MAb 1303, which retain equivalent affinity for PA, are 10- to 100-fold less potent in neutralizing anthrax toxin in vitro. Addition of Fc receptor-blocking antibodies also greatly reduced the activity of MAb 1303. Moreover, we found that the neutralizing activity of mouse, rabbit, and human antisera elicited by PA vaccines was effectively abrogated by blocking Fc receptors. Selection of an anti-PA MAb by using a functional assay that is a surrogate for protection has resulted in the identification of a fully human MAb with potent activity in vivo and uncovered a previously unrecognized mechanism of antibody-mediated toxin neutralization that is important for currently used anthrax vaccines.
Infection and Immunity 11/2006; 74(10):5840-7. · 4.16 Impact Factor
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ABSTRACT: Expression of the type I receptor for Fc domain of immunoglobulin (Ig)G (Fc gammaRI or CD64) is restricted to myeloid effector cells, such as monocytes, macrophages and a subset of dendritic cells. Previous work has indicated a role for Fc gammaRI in antibody-dependent phagocytosis and lysis of tumour cells. We hypothesised that tagging of tumour cells with an anti-Fc gammaRI single chain Fv (sFv) may facilitate targeting to this receptor on effector cells, thereby initiating tumour cytotoxicity. A vector encoding the sFv for an Fc gammaRI-specific antibody (H22), linked to the transmembrane domain of platelet-derived growth factor was constructed. Transfected tumour cells expressed high surface levels of functional H22-sFv, which greatly enhanced susceptibility for phagocytosis and lysis by monocytes and macrophages. The expression of H22-sFv evoked the ability of tumour cells to directly activate monocytes, as evidenced by phosphorylation of mitogen-activated protein kinase and secretion of the inflammatory cytokines interleukin (IL)-1beta, tumour necrosis factor-alpha and IL-6. Moreover, growth of tumour cells in mice expressing H22-sFv was profoundly delayed (or absent) in transgenic mice expressing human Fc gammaRI. These results demonstrated that tumour cells can be readily modified to activate cell effector mechanisms, a strategy that may be useful for in vivo targeting in patients.
British Journal of Haematology 03/2006; 132(3):317-25. · 4.94 Impact Factor
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Annet van Royen-Kerkhof,
Elisabeth A M Sanders,
Vanessa Walraven,
Marleen Voorhorst-Ogink,
Eirikur Saeland,
Jessica L Teeling,
Arnout Gerritsen,
Marc A van Dijk,
Wietse Kuis,
Ger T Rijkers, Laura Vitale,
Tibor Keler,
Steven E McKenzie,
Jeanette H W Leusen,
Jan G J van de Winkel
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ABSTRACT: A fully human IgG1 kappa antibody (MDE-8) was generated, which recognised Fc-gamma receptor IIa (FcgammaRIIa) molecules on CD32 transfectants, peripheral blood monocytes, polymorphonuclear cells and platelets. This antibody blocked FcgammaRIIa ligand-binding via its F(ab')(2) fragment. Overnight incubation of monocytes with F(ab')(2) fragments of MDE-8 leads to a c. 60% decrease in cell surface expression of FcgammaRIIa. MDE-8 whole antibody induced a concomitant c. 30% decrease of FcgammaRI on THP-1 cells and monocytes. In humans FcgammaRIIa plays an important role in the clearance of antibody-coated red blood cells in vivo. As an equivalent of FcgammaRIIa does not exist in mice, the in vivo effect of MDE-8 was studied in an FcgammaRIIa transgenic mouse model. In these mice, antibody-induced anaemia could readily be blocked by MDE-8. These data document a new human antibody that effectively blocks FcgammaRIIa, induces modulation of both FcgammaRIIa and FcgammaRI from phagocytic cells, and ameliorates antibody-induced anaemia in vivo.
British Journal of Haematology 08/2005; 130(1):130-7. · 4.94 Impact Factor
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Venky Ramakrishna,
John F Treml, Laura Vitale,
John E Connolly,
Thomas O'Neill,
Patricia A Smith,
Charles L Jones,
Li-Zhen He,
Joel Goldstein,
Paul K Wallace,
Tibor Keler,
Michael J Endres
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ABSTRACT: Targeting recycling endocytic receptors with specific Abs provides a means for introducing a variety of tumor-associated Ags into human dendritic cells (DCs), culminating in their efficient presentation to T cells. We have generated a human mAb (B11) against the mannose receptor that is rapidly internalized by DCs through receptor-mediated endocytosis. By genetically linking the melanoma Ag, pmel17, to Ab B11, we obtained the fully human fusion protein, B11-pmel17. Treatment of DCs with B11-pmel17 resulted in the presentation of pmel17 in the context of HLA class I and class II molecules. Thus, potent pmel17-specific T cells were cytotoxic toward gp100(+) HLA-matched melanoma targets, but not HLA-mismatched melanoma or gp100(-) nonmelanoma tumor lines. Importantly, competitive inhibition of lysis of an otherwise susceptible melanoma cell line by cold targets pulsed with known gp100 CD8 T cell epitopes as well as a dose-dependent proliferative response to Th epitopes demonstrates that DCs can process targeted Ag for activation of cytotoxic as well as helper arms of the immune response. Thus, the specific targeting of soluble exogenous tumor Ag to the DC mannose receptor directly contributes to the generation of multiple HLA-restricted Ag-specific T cell responses.
The Journal of Immunology 04/2004; 172(5):2845-52. · 5.79 Impact Factor
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Tibor Keler,
Ed Halk, Laura Vitale,
Tom O'Neill,
Diann Blanset,
Steven Lee,
Mohan Srinivasan,
Robert F Graziano,
Thomas Davis,
Nils Lonberg,
Alan Korman
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ABSTRACT: The immune modulatory molecule CTLA-4 (CD152), through interactions with the B7 costimulatory molecules, has been shown to be a negative regulator of T cell activation in various murine model systems. Abs that block CTLA-4 function can enhance immune responses that mediate potent antitumor activity. However, CTLA-4 blockade can also exacerbate autoimmune disease. The safety and activity of anti-CTLA-4 Abs in primates has not been addressed. To that end, we generated human Abs against CTLA-4 using transgenic mice expressing human Ig genes. A high affinity Ab (10D1) that blocked the binding of CTLA-4 to the B7-1 and B7-2 ligands and had cross-reactivity with macaque CTLA-4 was chosen for further development. Administration of 10D1 to cynomolgus macaques significantly enhanced Ab responses to hepatitis surface Ag and a human melanoma cell vaccine. Anti-self Ab responses as measured by immunoassays using lysate from melanocyte-rich tissues were elicited in those animals receiving the melanoma cell vaccine and anti-CTLA-4 Ab. Remarkably, chronic administration of 10D1 did not result in measurable polyclonal T cell activation, significant alteration of the lymphocyte subsets, or induce clinically observable autoimmunity. Repeated dosing of the 10D1 did not elicit monkey anti-human Ab responses in the monkeys. These observations support the development of CTLA-4 blockade for human immunotherapy.
The Journal of Immunology 01/2004; 171(11):6251-9. · 5.79 Impact Factor
