CD19-directed chimeric antigen receptor T cell (CART19) therapy is efficient and approved for relapsed/refractory diffuse large B cell lymphoma (DLBCL). To increase durable antitumor response, we previously designed tandem CART19/20 cells and shown longer progression-free survival. However, a proportion of CART19/20-treated patients will finally progress and require salvage therapies. In this study, we analyzed data from five patients with relapsed/refractory DLBCL who had disease progression or relapse following CART19/20 therapy and then treated with PD-1-blocking antibodies as salvage therapy. Two of five patients acquired complete remissions after anti-PD-1 therapy, including one patient remained ongoing remission for more than 21 months. One patient achieved a partial remission, and the other two had progressive diseases. No ≥ grade 3 treatment-related adverse events or cytokine release syndrome was observed. Immunohistochemistry of tumor specimens revealed higher PD-1/PD-L1 expression in responsive patients with anti-PD-1 therapy as compared to that in non-responders. After anti-PD-1 treatment, circulating T cells were activated in responders, and no significant expansion of CART19/20 cells was detected. Our data suggest that PD-1 blockade therapy can be active in patients with relapsed/refractory DLBCL after failure of CAR T cell therapy who had PD-L1 expression in tumor cells and high PD-1 level in tumor-infiltrated T cells.
Keywords: Anti-PD-1; CART; DLBCL; PD-1/PD-L1; Salvage therapy.