Date of Award
Darnell Robert Laboratory
breast cancer immunotherapy, ovarian cancer immunotherapy, cdr2, adaptive T cell transfer therapy
Patients with paraneoplastic cerebellar degeneration (PCD), a form of neuronal autoimmunity, have a co-occurring natural immune response against a protein called cdr2 in their breast and ovarian carcinomas, and thus provide an innovative starting point for understanding how to harness the immune system to fight cancer. We previously demonstrated cdr2-specific cytotoxic T lymphocytes (CTL) in the peripheral blood of HLA-A2.1+ PCD patients, suggesting that CTLs mediate tumor immunity in these patients. Cdr2 is expressed by a large proportion of breast and ovarian tumors from individuals who do not develop neurological disease, suggesting that immune responses to this antigen may develop independently of autoimmune responses. Here we explore establishing cdr2 as a target for breast and ovarian cancer immunotherapy by identifying naturally processed A2.1-restricted epitopes of cdr2. Immunization of A2.1 transgenic mice with recombinant adenovirus encoding human full length cdr2 led to the identification of two naturally processed A2.1-restricted human cdr2 peptides: cdr2(289-297) and cdr2(290-298). Mouse-derived A2.1-restricted cdr2(289-297)-specific CTLs were able to target cells expressing endogenous human cdr2, but also cross-reacted with endogenous mouse cdr2, resulting in partial tolerance to this epitope. In contrast, mouse-derived A2.1-restricted cdr2(290-298)-specific CTL were capable of recognizing tumor cells expressing endogenous human cdr2, but were unable to recognize mouse cdr2 due to nonhomology of the human and mouse cdr2(290- 298) epitopes. cdr2(290-298)-specific CTL clones were isolated, and their TCR gene cloned. Transfer of the mouse-derived TCR into human CD8+ T cells turned them into efficient cdr2-specific CTLs. We have detected CD8+ T cells specific for both cdr2(289-297) and cdr2(290-298) in peripheral blood from A2.1+ PCD patients by tetramer staining. This correlates the presence of T cells specific to these epitopes with PCD and effective anti-gynecologic tumor immunity, and suggests that these are bona fide tumor-associated CTL epitopes. We conclude swthat gene transfer of TCR specific for cdr2(290-298) could provide the basis for potent breast and ovarian cancer immunotherapies, while cdr2(289-297)-specific T cells, able to target both mouse and human cdr2, offer a platform for generating a humanized animal model to investigate the whether cdr2-TCR gene transfer is possible without inducing neuronal autoimmunity.
Santomasso, Bianca D., "From Naturally Occurring Tumor Immunity to Supernatural T Cells: Isolation and Characterization of a Murine T Cell Receptor Specific for Human Breast and Ovarian Tumor Antigen Cdr2" (2007). Student Theses and Dissertations. 21.