A Phase 2 Study of pembrolizumab after Autologous Stem Cell Transplantation in Patients with T-Cell non-Hodgkin Lymphoma.

Autologous stem cell transplantation (ASCT) is often used as consolidation for several subtypes of peripheral T-cell lymphoma (PTCL) in first remission. However, many patients relapse after ASCT and have a very poor prognosis. There are no approved treatment options for post-transplant maintenance or consolidation in PTCL. PD-1 blockade has demonstrated some efficacy for patients with PTCL. We therefore conducted a phase 2 multicenter study of the anti-PD-1 monoclonal antibody pembrolizumab after ASCT in patients with PTCL in first remission. Pembrolizumab was administered at 200 mg IV every 3 weeks for up to 8 cycles within 21 days from post-ASCT discharge (and within 60 days of stem cell infusion). The primary endpoint was progression-free survival (PFS) at 18 months post-ASCT. Twenty-one patients were treated on this study and (14) 67% completed 8 cycles of treatment. Among all evaluable patients, 13/21 were alive and progression-free at 18-months post-ASCT, meeting the study's primary endpoint. The estimated 18-month PFS was 83.6% (95% CI: 68 - 100), and OS 94.4% (95% CI: 84 - 100). The toxicity profile was consistent with the known toxicity profile of pembrolizumab with no grade 5 toxicities. In conclusion, PD-1 blockade after ASCT with pembrolizumab is feasible with a favorable safety profile and promising activity, supporting further confirmatory studies. This trial was registered at www.clinicaltrials.gov (NCT02362997).