Abstract 5583: SUV39H1 disruption enhances the persistence and anti-tumor efficacy of CD28-costimulated human CAR T cells
Authors: Jain Nayan , Zhao Zeguo , Koche Richard , Gozlan Yosi , Brocks David , Raveh-Sadka Tali , Wells Danny , Dobrin Anton , Shi Yuzhe , Lopez Michael , Gunset Gertrude , Sadelain Michel 
Published: June 2022

Abstract
Retrovirally encoded CD19-specific CARs that incorporate CD28 and CD3z signaling motifs (Rv-1928z) have induced remarkable responses in patients with refractory leukemia and lymphoma. These CARs induce a strong effector differentiation program in T cells that can limit their persistence and result in T cell dysfunction. This induction of terminal effector differentiation is accompanied by transcriptional and epigenetic changes resulting in induction of effector transcriptional factors, inhibitory receptors, and suppression of memory associated genes. In this study, we examine the effect of modulating the epigenome of human Rv-1928z CAR T cells by disruption of the histone methyl transferase, SUV39H1, which has been implicated in regulating memory to effector transition in murine T cells (Pace et al. 2018).
To assess the impact of SUV39H1 on human Rv-1928z CAR T cells, we treated immune deficient mice bearing the human ALL cell line, NALM6, with limiting doses of SUV39H1-edited T cells. SUV39H1 editing (SUV39H1etd) significantly enhanced the anti-tumor efficacy of Rv-1928z CAR T cells relative to non-edited counterparts, with 9/10 NALM6 bearing mice treated with SUV39H1etd Rv-1928z surviving over the duration of observation (90 days) as compared to 1/12 mice treated with WT Rv-1928z. This enhanced tumor control in SUV39H1etd Rv-1928z CAR T cells was associated with greater initial CAR T cell proliferation upon tumor encounter and enhanced long-term CAR T cell persistence (&gt; day 50).
To assess whether the persisting SUV39H1etd Rv-1928z CAR T cells can mount an effective effector response upon tumor rechallenge, we modified the stress test model such that post primary tumor clearance (day 17), mice were rechallenged by tumor 5 times over 70 days. SUV39H1etd Rv-1928z CAR T cells outperformed WT Rv-1928z CAR T cells in eliminating NALM6 upon rechallenge. Paired genome accessibility (ATACseq) and transcriptional analysis revealed epigenetic changes associated with SUV39H1 loss in Rv-1928z CAR T cells that promote expression of memory associated transcription factors and receptors while reducing expression of inhibitory receptors and transcriptional factors associated with T cell dysfunction. In summary, we find that loss of SUV39H1 in human Rv-1928z CAR T cells enhances their anti-tumor efficacy by bringing about changes in their epigenome that enhance their functional persistence.
Citation Format: Nayan Jain, Zeguo Zhao, Richard Koche, Yosi Gozlan, David Brocks, Tali Raveh-Sadka, Danny Wells, Anton Dobrin, Yuzhe Shi, Michael Lopez, Gertrude Gunset, Michel Sadelain. SUV39H1 disruption enhances the persistence and anti-tumor efficacy of CD28-costimulated human CAR T cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5583.