CAR-T Cell Therapy in Primary Mediastinal B-cell Lymphoma

Abstract

A specific type of CAR-T cell therapy, the CAR19 therapy has demonstrated notable efficacy for relapsed or refractory (R/R) hematologic cancers, including B-cell lymphomas. After the recent reclassification of the rare subtype Primary Mediastinal B-cell Lymphoma (PMBCL) from general Diffuse Large B-cell Lymphoma (DLBCL), questions have been raised about the application of immunotherapies in this cancer, including the most discussed CAR-T cell therapy. The CAR-T cell therapy, more specifically the CAR19, exerts anti-tumor effects in multiple mechanisms, including different cytotoxic pathways—apoptosis triggering via perforin–granzyme release and Fas/FasL-pathway—driven by calcium-dependent signaling MAPK, PI3K/Akt, and NF-κB. Multiple extant clinical trials have evaluated the response of PMBCL patients to CAR19, specifically the Axi-cel, Liso-cel, and Tisa-cel therapies, focusing the rates of complete response (CR), progression-free survival (PFS), and the overall survival (OS). Studies exclusive to PMBCL patients showed that bridging therapies and other first-line treatments did not influence CAR19 effectiveness, while post-relapse application of Pembrolizumab yielded durable CRs in some patients, and allo-HSCT was associated with high mortality. The CAR-SIE trial in Italy, comparing Axi-cel CAR19 in PMBCL cancer with other B-cell lymphomas, demonstrated a better result in PMBCL patients with higher ORR, CR, and PFS. This paper integrates the underlying mechanisms of CAR19 with clinical trials, aiming to demonstrate both the potential and the limitations of this therapy in PMBCL cancer.