Second Line CD19 CAR-T vs Platinum Salvage and Autologous Stem Cell Transplant for Primary Mediastinal B-Cell...

Primary mediastinal B-cell lymphoma (PMBCL) is a rare form of large B-cell lymphoma (LBCL) with around 90% of patients cured with frontline treatment. For relapsed or refractory (R/R) disease, the optimal treatment is unclear. CD19 chimeric antigen receptor-T cell (CAR-T) has been established as the preferred second line (2L) treatment for primary refractory or early relapsing LBCL based on the overall survival benefits observed in the landmark phase III trials. However, PMBCL patients were underrepresented on these pivotal studies. This study evaluated outcomes of 252 patients treated with 2L therapies for R/R PMBCL at 14 US institutions between 2001 and 2025. Platinum-based salvage with intent to proceed to high dose therapy and autologous stem cell transplant (HDT/ASCT) (platinum cohort) and CD19 CAR-T (CAR-T cohort) were given as 2L therapy in the real-world setting in 157 and 26 patients, respectively. Overall response rate (ORR), complete response (CR) rate and median progression-free survival (PFS) were significantly higher in the CAR-T cohort compared with the platinum cohort (ORR: 91.3% vs 44.2%, p <0.001; CR 65.2% vs 14.7%, p<0.001; median PFS not reached vs 3.5 months, hazard ratio (HR) 0.28, 95% CI 0.15-0.54, p=0.001). No significant difference was observed in overall survival. This study demonstrated superior response rate and PFS of CD19 CAR-T over platinum-based salvage with intent to proceed to HDT/ASCT as 2L treatment for R/R PMBCL.