Ibrutinib, rituximab, and lenalidomide in unfit or frail patients aged 75 years or older with de novo diffuse large B-cell lymphoma: a phase 2, single-arm study

Abstract

Background: The optimal treatment for older adults with diffuse large B-cell lymphoma (DLBCL) needs to be further explored due to patient comorbidities, standard immunochemotherapy intolerance, and unfavourable genetic features. We did a phase 2 trial of ibrutinib, rituximab, and lenalidomide (iR2) to evaluate the efficacy and safety in older adult patients with de novo DLBCL.

Methods: In this phase 2, single-arm study, unfit or frail patients with de novo DLBCL aged 75 years or older were enrolled at Shanghai Ruijin Hospital, Shanghai, China. During the induction phase from cycle 1 to 6, 560 mg ibrutinib was given orally daily throughout each 21-day treatment cycle, 375 mg/m² rituximab was given intravenously on day 1, and 25 mg lenalidomide was given orally daily from day 1 to 10 in each cycle. Patients who had a complete response after induction were given another 6 cycles of lenalidomide maintenance (25 mg orally daily from day 1 to 10 every 21 days from cycle 7 to 12). The primary endpoint was complete response rate after 6 cycles or at the end of the induction treatment. This trial is registered with ClinicalTrials.gov, NCT03949062.

Findings: Between May 15, 2019, and May 8, 2020, a total of 30 patients were enrolled. The end of induction complete response rate was 56·7% (95% CI 37·4-74·5), and overall response rate was 66·7% (95% CI 47·2-82·7). With a median follow-up of 27·6 months (IQR 23·9-29·6), the 2-year progression-free survival rate was 53·3% (95% CI 34·3-69·1) and the 2-year overall survival rate was 66·7% (95% CI 46·9-80·5). The main grade 3-4 haematological adverse events were neutropenia (seven patients [23%]), thrombocytopenia (three patients [10%]), and anaemia (two patients [7%]). The most common grade 3-4 non-haematological adverse event was pulmonary infection (seven patients [23%]). Atrial fibrillation was observed in three (10%) patients, including one grade 2 and two grade 3.

Interpretation: A chemotherapy-free iR2 regimen is clinically effective and safe and warrants further investigation in phase 3 trials as first-line treatment in older adult patients with DLBCL.

Funding: National Natural Science Foundation of China, Shanghai Municipal Education Commission Gaofeng Clinical Medicine Grant Support, Clinical Research Plan of Shanghai Hospital Development Center, and Multicenter Clinical Research Project by Shanghai Jiao Tong University School of Medicine.