Checkpoint Blockade Therapy May Sensitize Hodgkin Lymphoma to Subsequent Therapy

Background: Relapsed or refractory (R/R) Hodgkin lymphoma (HL) remains a significant clinical problem. Recently checkpoint blockade therapy (CBT) has shown striking activity in this setting, but the complete response (CR) rate is modest. Patients who relapse after CBT have limited therapeutic options. A prior, retrospective study showed that after anti-PD-1 therapy the objective response rate to chemotherapy alone was 61% (Rossi et al 2017). We investigated the effect of treatment subsequent to CBT in a large international multicenter retrospective analysis. Methods: Seventeen centers across the US and Canada are participating in this study to date. Medical records of each institution were queried to identify HL patients who received CBT and were subsequently treated with an additional line of therapy. The primary aim of this analysis was to determine the best response to post-CBT treatment in patients who discontinued CBT due to progression of disease (PD), preparation for stem cell transplant (SCT), or toxicity. Patients who discontinued CBT due to CR, and patients whose best response could not be determined due to death from another cause were excluded from analysis. Responses were assessed using Lugano criteria. Survival status was analyzed for the entire study population and stratified by post-CBT treatment regimen and disease subgroups using the Kaplan-Meier method. Progression free survival (PFS) was calculated for patients with at least stable disease (SD) to post-CBT treatment. Log rank tests were performed to test for statistical significance. Two-sided P