Outcomes of patients with relapsed or refractory primary mediastinal B-cell lymphoma after frontline DA-EPOCH-R

Abstract

Introduction: Most patients diagnosed with primary mediastinal B-cell lymphoma (PMBCL) achieve cure following standard of care therapy with frontline DA-EPOCH-R. However, treatment strategies following relapse after DA-EPOCH-R are not well defined.

Methods: We performed a retrospective review of PMBCL patients relapsed/refractory (R/R) after frontline DA-EPOCH-R to obtain better insight on outcomes with salvage therapy and autologous stem cell transplant (Auto-SCT).

Results: Our cohort consisted of 107 patients with R/R PMBCL. Ninety patients qualified for the intention to treat (ITT) salvage therapy (ST) analysis. With a median follow up of 48.9 months in the ST analysis, the median progression-free survival (PFS) was 5.4 months (95% CI: 2.3-not reached (NR)) with 5-year OS rate of 78% (95% CI: 69-88). Compared to relapsed patients (relapsing > 6 months after frontline DA-EPOCH-R, N=23), refractory patients (relapsing < 6 months after frontline DA-EPOCH-R, N=67) had inferior overall response rate (ORR) (48% vs 83%), complete remission (CR) rate (19% vs 44%), and 2-year PFS rate (30% vs 69%) with initial ST. Forty-eight patients (53%) underwent Auto-SCT after ST with estimated 5-year PFS and overall survival (OS) rates of 85% (95% CI: 75-96) and 88% (95% CI: 79-99), respectively. There were no relapses among 29 patients with CR prior to Auto-SCT.

Conclusions: This analysis is the largest review of R/R PMBCL to date and demonstrates unfavorable outcomes for patients with refractory disease after frontline DA-EPOCH-R chemotherapy. Patients able to receive Auto-SCT, especially those with CR prior to Auto-SCT, had excellent outcomes.