Abstract P129

You Don't Always Need a Transplant: Checkpoint Inhibitors Can Deliver Lasting Remissions in Relapsed and Refractory Classical Hodgkin Lymphoma

The PD1-targeting checkpoint inhibitors (CPI) nivolumab and pembrolizumab are established treatments for relapsed/refractory (R/R) classical Hodgkin Lymphoma (cHL) (Keynote-087/204, Checkmate-205). We retrospectively studied CPI-treated R/R cHL patients, evaluating survival, response, toxicity and post-CPI therapy in R.

Between 2015-2025, 26 patients received CPI monotherapy (pembrolizumab n=16, nivolumab n=10) for R/R cHL. Median age was 40 (range 22-87) and 14 were female. The median number of prior treatments was 3 (2-11); 69% had advanced stage at diagnosis. The commonest first-line treatment was ABVD (n=19); 19 had primary refractory disease. Second-line treatments were ICE (n=10) or GDP (n=7), and third-line: brentuximab (n=10) or chemotherapy (n=8). Nine had autologous and 5 allogeneic stem cell transplant (SCT) pre-CPI (2 had both). CPI was salvage therapy in third line (n=5) or fourth line and beyond (n=21). Median CPI treatment duration was 13 months.

For the cohort, ORR, complete response (CR), partial response (PR), stable disease (SD) and progression (PD) were 73.07%, 69.23%(n=18), 3.8%(n=1), 3.8% and 11.53%(n=3) respectively; 3 died before assessment. Median response duration was 21.9 months (95% CI 8.2-46.9). Eight proceeded to SCT as consolidation in CR (n=6), PR (n=1) or SD (n=1); median time from last CPI to transplant was 8.15 weeks. Post-transplant, 5 remain in CR, 3 progressed/relapsed. GVHD occurred in 6 patients, all grade 1-2. Of 12 in CR without SCT, 9 remain in CR (median treatment 13.4 months). Eight CPI-associated immune-related adverse events(AE) occurred in 6 patients (hepatitis, colitis, autoimmune haemolytic anaemia, panhypopituitarism, arthropathy, pneumonitis, neurotoxicity and thyrotoxicosis).

At a median follow-up of 4 years, 14 patients remain in CR. Median PFS was 4.07 years (95% CI 2.4-NE); 5-year Kaplan-Meier PFS was 47% (95% CI 23-67) overall and 66% (95% CI 16-91) in the SCT group. Median OS not reached; estimated 5-year OS 59% (95% CI 30-79). On Cox regression, older age was associated with significantly higher progression risk (HR 1.06, 95% CI 1.02-1.10; p=0.001) on univariate and multivariate analysis.

Our study demonstrates the real-world effectiveness of CPIs, with unselected patients achieving durable responses and an acceptable AE profile. It confirms that heavily pretreated patients can be safely consolidated with SCT, while many non-SCT patients in CR maintain durable remission. A UK-wide study is ongoing.