Targeting the T cell receptor β-chain constant region for immunotherapy of T cell malignancies

Paul M Maciocia, Patrycja A Wawrzyniecka, Brian Philip, Ida Ricciardelli, Ayse U Akarca, Shimobi C Onuoha, Mateusz Legut, David K Cole, Andrew K Sewell, Giuseppe Gritti, Joan Somja, Miguel A Piris, Karl S Peggs, David C Linch, Teresa Marafioti, Martin A Pule

Mature T cell cancers are typically aggressive, treatment resistant and associated with poor prognosis. Clinical application of immunotherapeutic approaches has been limited by a lack of target antigens that discriminate malignant from healthy (normal) T cells. Unlike B cell depletion, pan-T cell aplasia is prohibitively toxic. We report a new targeting strategy based on the mutually exclusive expression of T cell receptor β-chain constant domains 1 and 2 (TRBC1 and TRBC2). We identify an antibody with unique TRBC1 specificity and use it to demonstrate that normal and virus-specific T cell populations contain both TRBC1(+) and TRBC2(+) compartments, whereas malignancies are restricted to only one. As proof of concept for anti-TRBC immunotherapy, we developed anti-TRBC1 chimeric antigen receptor (CAR) T cells, which recognized and killed normal and malignant TRBC1(+), but not TRBC2(+), T cells in vitro and in a disseminated mouse model of leukemia. Unlike nonselective approaches targeting the entire T cell population, TRBC-targeted immunotherapy could eradicate a T cell malignancy while preserving sufficient normal T cells to maintain cellular immunity.