Nivolumab combined with brentuximab vedotin for R/R primary mediastinal large B-cell lymphoma: a 3-year follow-up

: Patients with relapsed/refractory primary mediastinal large B-cell lymphoma (R/R PMBL) have poor responses to salvage therapy. Nivolumab and brentuximab vedotin (BV) showed promising early efficacy in patients with R/R PMBL in the phase I/II open-label, multicenter CheckMate 436 study; we report safety and efficacy findings from the 3-year follow-up. Eligible patients were aged ≥ 15 years with R/R PMBL previously treated with either high-dose chemotherapy plus autologous hematopoietic cell transplantation (HCT) or ≥ 2 prior multi-agent chemotherapies, and had Eastern Cooperative Oncology Group performance status 0-1 and CD30 expression ≥ 1%. Patients were treated with nivolumab 240 mg and BV 1.8 mg/kg once every 3 weeks until disease progression or unacceptable toxicity. Primary endpoint was objective response rate (ORR); secondary endpoints included complete response rate, duration of response, progression-free survival (PFS), and overall survival (OS). Safety was monitored throughout. At final database lock (March 30, 2022), 29 patients had received nivolumab plus BV; median follow-up was 39.6 months. Investigator-assessed ORR was 73.3%; median (range) time to response was 1.3 (1.1-4.8) months. Median PFS was 26.0 months; median OS was not reached. PFS and OS rates (95% CI) at 24 months were 55.5% (32.0%-73.8%) and 75.5% (55.4%-87.5%), respectively. The most frequently occurring grade 3/4 treatment-related adverse event was neutropenia. Consolidative HCT was received by 12 patients, with a 100-day complete response rate of 100.0%. This 3-year follow-up showed long-term efficacy for nivolumab plus BV in R/R PMBL, with no new safety signals. Clinicaltrials.gov: NCT02581631.