Anti-CD25 Radioimmunotherapy with BEAM Autologous Hematopoietic Cell Transplantation Conditioning in Hodgkin Lymphoma.

Abstract High-risk relapsed or refractory (R/R) classical Hodgkin lymphoma (HL) is associated with poor outcomes after conventional salvage therapy and autologous hematopoietic cell transplantation (AHCT). Post-AHCT consolidation with brentuximab vedotin (BV) improves progression-free survival (PFS), but with increasing use of BV early in the treatment course, the utility of consolidation is unclear. CD25 is often expressed on Reed-Sternberg cells and in the tumor microenvironment in HL and we hypothesized that the addition of 90Y-antiCD25 (aTac) to BEAM AHCT would be safe and result in a transplantation platform that is agnostic to prior HL-directed therapy. Twenty-five patients with high-risk R/R HL were enrolled onto this phase 1 dose-escalation trial of aTac-BEAM. Following an imaging dose of 111In-antiCD25, 2 patients had altered biodistribution and a third developed an unrelated catheter-associated bacteremia; therefore 22 patients ultimately received therapeutic90 Y-aTac-BEAM AHCT. No dose-limiting toxicities were observed and 0.6mCi/kg was deemed the recommended phase 2 dose, the dose at which the heart wall would not receive > 2500cGy. Toxicities and time to engraftment were similar to those observed with standard AHCT, though 95% of patients developed stomatitis (all grade 1-2 per Bearman toxicity scale). Seven relapses (32%) were observed, most commonly in patients with ≥3 risk factors. The estimated 5-year PFS and overall survival probabilities among 22 evaluable patients were 68% and 95%, respectively, and non-relapse mortality was 0%. aTac-BEAM AHCT was tolerable in patients with high-risk R/R HL and we are further evaluating the efficacy of this approach in a phase 2 trial. The clinical trial was registered at clinicaltrials.gov (NCT01476839).