Rituximab-PECC induction followed by ⁹⁰Y-ibritumomab tiuxetan consolidation in relapsed or refractory DLBCL patients who are ineligible for or have failed ASCT: results from a phase II HOVON study

Patients with relapsed/refractory diffuse large B-cell lymphoma (DLBCL) after, or ineligible for, autologous stem cell transplantation (ASCT) have a dismal prognosis. This phase II study evaluated treatment with R-PECC (rituximab, prednisolone, etoposide, chlorambucil, lomustine), every 28 days for 4 cycles in 62 patients, followed by radio-immunotherapy consolidation with ⁹⁰Y-ibritumomab tiuxetan in responsive patients. Primary endpoints were failure-free survival (FFS) and incidence of grade ≥3 adverse events from start of ⁹⁰Y-ibritumomab tiuxetan. The overall response rate after R-PECC was 50%. Twenty-nine of 31 responsive patients proceeded to ⁹⁰Y-ibritumomab tiuxetan. Five out of 15 partial remission patients converted to complete remission after ⁹⁰Y-ibritumomab tiuxetan. One-year FFS and overall survival (OS) from start of ⁹⁰Y-ibritumomab tiuxetan was 52% (95% confidence interval [CI], 33–68%) and 62% (95% CI, 42–77%), respectively. One-year FFS and OS from start of R-PECC was 28% (95% CI, 17–39%) and 49% (95% CI, 36–61%), respectively. Toxicities of R-PECC and ⁹⁰Y-ibritumomab tiuxetan were mainly haematological. In conclusion, for relapsed DLBCL patients the largely oral R-PECC regimen achieves promising response rates, combined with an acceptable safety profile. Consolidation with ⁹⁰Y-ibritumomab tiuxetan resulted in long-term response durations in approximately one third of the patients that received it.