Dados do Resumo

Título

Targeting PRC2 enhances the antitumor cytotoxic capacity of anti-CD19 CAR-T cells against hematological malignancies

Introdução

Chimeric Antigen Receptor (CAR) T cell therapy was adopted as a clinical modality for patients with relapsed/refractory hematological malignancies. Despite the clinical efficacy of CAR-T cell therapy, a considerable fraction of patients still relapses during the first months following CAR-T cell infusion. We believe that part of the problem is related to epigenetic mechanisms involved on T cell suppression, which could be reverted trought the use of epigenetic modulators.

Objetivo

The aim of this study is to evaluate whether inhibition of the PRC2 complex in human CAR-T cells can enhance their antitumor efficacy both in vitro and in vivo.

Métodos

We initially assessed the modulatory effects of inhibitors targeting different subunits of the Polycomb Repressive Complex 2 (PRC2) — specifically A395 and GSK343 — on the effector function of CD8+ T lymphocytes isolated from PBMCs of healthy donors (CEP 2710/19). Additionally, we developed an in-house anti-CD19 CAR-T cell system, which was treated with these PRC2 inhibitors or their respective controls. To evaluate cytotoxic potential, anti-CD19 CAR-T cells, with or without PRC2 inhibitor treatment, were co-cultured with Nalm-6 CD19+ cells, a B-ALL cell line. For in vivo antitumor activity, anti-CD19 CAR-T cells, treated or untreated with PRC2 inhibitors, were transferred into NSG mice previously engrafted with Nalm-6 CD19+ cells. Furthermore, to assess the clinical impact of PRC2 inhibition, anti-CD19 CAR-T cells derived from infusion products of patients with B-ALL and Non-Hodgkin lymphoma were stimulated and treated in vitro with epigenetic inhibitors and challenged with tumor cell lines to the evaluation of their cytotoxicity capacity.

Resultados

The inhibition of the PRC2 complex increased the frequency of CD8+ T cells expressing activation markers (CD25, CD69 and HLA-DR), inflammatory mediators (IFN-γ and TNF-α), and cytotoxic factors such as granzyme B (GzmB) and Perforin 1. Additionally, PRC2 inhibition induced an effector memory profile characterized by GzmB+ and reduced the frequency of inhibitory markers. Furthermore, A-395 and GSK343 promoted the differentiation of GZMB+ effector memory 19BBζ CAR-T cells and enhanced their antitumor activity both in vitro and in vivo. Consistent with their long-lasting antitumor activity, PRC2-inhibited 19BBζ CAR-T cells did not exhibit any signs of dysfunctionality/exhaustion. Besides, TCR restimulation along with PRC2 inhibition of patient-derived anti-CD19 CAR-T cells also induced the development of GZMB+ effector memory cells and elicited potent antitumor responses against CD19+ Daudi cells. In line with this, the gene signature derived from in-house PRC2-inhibited 19BBζ CAR-T cells was enriched in tisagenlecleucel (tisa-cel) BBζ CAR-T cell therapy responders with large B-cell lymphoma.

Conclusões

Based on a characterization using three complementary approaches (in vitro assays with human CD8+ T lymphocytes, in vitro and in vivo assays with in-house generated CAR-T cells, and in vitro assays with CAR-T cells derived from patients with B-ALL and NHL), our results demonstrated that targeting PRC2 represents a promising approach to enhance a functional effector program in CAR-T cells against hematological malignancies.

Financiador do resumo

FAPESP, CAPES, CNPq

Palavras Chave

CAR-T Cell; epigenetic; hematological malignancies