Rescuing CTLs from undergoing TCR restimulation induced necroptosis improves tumor control (VAC7P.1034)

Abstract

Abstract Engineering T cells with tumor epitope reactive T cell receptors (TCR) for adoptive cell transfer (ACT) therapy requires rapid proliferation and expansion, resulting in replicative senescent phenotype and increased susceptibility to cell death. Cell death may occur as apoptosis (programmed) or necrosis (un-programmed), or programmed necrosis (termed necroptosis). Our data shows that human T cells engineered with tumor epitope tyrosinase specific TIL1383I TCR upon restimulation with cognate antigen undergo caspase independent and reactive oxygen species mediated cell death cell death that involves JNK. Further, electron microscopic studies revealed that primarily effector-memory phenotype bearing T cells underwent antigen stimulated cell death resembling necroptosis, which was averted by pretreating with necroptosis inhibitor NecroX2 that inhibits RIPK1. Further, in vivo studies done to treat subcutaneously established B16-F10 tumors in C57BL/6 mice showed better tumor control when adoptively transferred tumor epitope gp100 reactive T cells were pretreated with NecroX2. Long-term tracking studies showed that NecroX2 pretreated T cells persisted better than the untreated T cells alone, and could account for differences in tumor growth. Our data highlights that understanding the morphology/type of cell death that a tumor reactive T cell may undergo upon TCR restimulation is important to effectively rescue anti-tumor T cells for increasing persistence and improving ACT.