ABSTRACT
One strategy to generate T-cell responses to tumors is to alter subdominant epitopes through substitution of amino acids that are optimal anchors for specific MHC molecules, termed heteroclitic epitopes. This approach is manually error-prone and time-consuming. In here, we describe a computer-based algorithm (EpitOptimizer) for the streamlined design of heteroclitic epitopes. Analysis of two cancer-related proteins showed that EpitOptimizer-generated peptides have enhanced MHC-I binding compared with their wild-type counterparts; and were able to induce stronger CD8+ T-cell responses against their native epitope. These data demonstrate that this approach can serve as the basis of epitope-engineering against cancer and intracellular pathogens.
Subject(s)
Cancer Vaccines/immunology , Computational Biology/methods , Epitopes/immunology , Peptides/immunology , Algorithms , Amino Acid Sequence , Animals , CD8-Positive T-Lymphocytes/immunology , Cancer Vaccines/genetics , Cancer Vaccines/metabolism , Cross Reactions , Epitopes/chemistry , Epitopes/genetics , Epitopes/metabolism , Female , Histocompatibility Antigens Class I/metabolism , Mice , Mice, Inbred C57BL , Mice, Transgenic , Models, Animal , Molecular Sequence Data , Mutagenesis, Site-Directed , Neoplasms , Peptides/chemistry , Peptides/genetics , Peptides/metabolism , Protein EngineeringABSTRACT
PURPOSE: This open-label study assessed the safety and immunogenicity of two doses and two routes of the anti-idiotypic monoclonal antibody abagovomab (formerly ACA125) in patients with epithelial ovarian, fallopian tube, or primary peritoneal cancer. EXPERIMENTAL DESIGN: Eligible patients from the three participating institutions were any stage at diagnosis, had relapsed, and had complete or partial response to additional chemotherapy. Patients were randomized to receive abagovomab at 2.0 versus 0.2 mg and i.m. versus s.c. for four immunizations every 2 weeks and then monthly for two additional immunizations. Planned evaluation included interval physical examinations and laboratory assessments with immune assessment, including HLA typing, human anti-mouse antibody, ELISA, and enzyme-linked immunospot. Patients were required to remain on study until week 10 (the first post-baseline Ab3 determination) to be considered for immunologic assessment. The primary end points were safety and immunogenicity primarily determined by Ab3 response. RESULTS: Forty-two patients received at least one vaccination and were eligible for safety analysis. Thirty-three patients were available for Ab3 analysis (removed for progression of disease, 6; withdrawal of consent, 2; unrelated adverse event, 1). The most common adverse events were self-limited pain at injection site, myalgia, and fever. No hematologic or nonhematologic toxicity grade>2 related to immunization was seen. Ab3 was detectable in all patients (median, 236,794 ng/mL); none of route of administration (P=0.6268), dose (P=0.4602), or cohort (P=0.4944) was statistically significant in terms of effect on maximum post-baseline Ab3 titer. Human anti-mouse antibody was not detectable at baseline but was present in all patients at week 16 (range, 488-45,000 ng/mL). CONCLUSIONS: Immunization with abagovomab is well tolerated and induced robust Ab3 responses at the two doses and routes tested. A phase III randomized study with abagovomab (2.0 mg s.c.) is warranted.
