Combination of chidamide and PD-1 blockade in Refractory/Relapsed aggressive large B-cell lymphomas with high risk of failing CAR-T therapy

Background Refractoriness and relapse after chimeric antigen receptor T-cell therapy have emerged as major challenges for immunotherapy of aggressive large B-cell lymphoma. Thus far, there is no consensus on how to address treatment failure and whether to administer maintenance therapy following CAR-T cell therapy. Methods From August 2017 through November 2022, 52 patients with refractory/relapsed aggressive LBCL who had a high risk of resistance to CAR-T cell therapy were given chidamide in combination with a PD-1 inhibitor as maintenance therapy following either CAR19/22 T-cell cocktail therapy or CAR19/22 T-cell cocktail therapy plus autologous stem cell transplantation (ASCT). Another 52 aggressive LBCL patients who had comparable baseline characteristics and received similar therapeutic regimens but did not receive any interventions following CAR-T cell therapy or CAR-T cell therapy plus ASCT were regarded as the control group to evaluate the efficacy and safety of the combination of chidamide and a PD-1 inhibitor. Results Among the 52 patients who received chidamide and a PD-1 inhibitor as maintenance therapy, with a median follow-up of 26.5 months (range: 1.1–53.8), neither the median progression-free survival (PFS) nor overall survival (OS) was reached, and the expected 2-year OS and PFS rates were 89 % and 77 %, respectively, which were superior to those of the control group (p < 0.001). Long-term chidamide administration and a specific genetic subtype of EZB were strongly associated with a better response after chidamide plus PD-1 blockade therapy. Additionally, long-term chidamide administration was significantly associated with prolonged persistence and reactivation of CD19-directed CAR-T cells in the peripheral blood. Adverse effects (AEs) were moderate and reversible, and no treatment-related deaths occurred. Conclusion Our results indicate that the combination of chidamide and PD-1 blockade as maintenance therapy could improve the outcomes of aggressive LBCL patients at high risk of failing CAR-T cell therapy.