ZNF683 marks a CD8+ T cell population associated with anti-tumor immunity following anti-PD-1 therapy for Richter syndrome [TCR-seq]

Unlike many other hematologic malignancies, Richter syndrome (RS), an aggressive B cell lymphoma originating from indolent chronic lymphocytic leukemia, is responsive to PD-1 blockade. To discover the determinants of response, we analyzed single-cell transcriptome data generated from 17 bone marrow samples longitudinally collected from 6 RS patients. Response was associated with intermediate exhausted CD8 effector/effector memory T cells marked by high expression of the transcription factor ZNF683, determined to be evolving from stem-like memory cells and divergent from terminally exhausted cells. This signature overlapped with that of tumor-infiltrating populations from PD-1 responsive solid tumors. ZNF683 was found to directly target key T cell genes (TCF7, LMO2, CD69) and impact pathways of T cell cytotoxicity and activation. Analysis of pre-treatment peripheral blood from 10 independent RS PD-1 treated patients, as well as solid tumor PD-1 treated patients, supported an association of ZNF683high T cells with response. Overall design: rhTCRseq