Durable complete responses from therapy with combined epratuzumab and rituximab: final results from an international multicenter, phase 2 study in recurrent, indolent, non-Hodgkin lymphoma.

Background: In this international, multicenter trial, the authors evaluated rituximab (anti-CD20) plus epratuzumab (anti-CD22) in patients with postchemotherapy relapsed/refractory, indolent non-Hodgkin lymphoma (NHL), including long-term efficacy.

Methods: Forty-nine patients with follicular NHL (FL) (N = 41) or small lymphocytic lymphoma (SLL) (N = 7) received intravenous epratuzumab 360 mg/m2 and then intravenous rituximab 375 mg/m2 weekly x4. The regimen was tolerated well.

Results: Twenty-two of 41 patients with FL (54%) had an objective response (OR), including 10 (24%) complete responses (CR) (CR/unconfirmed CR [CRu]), whereas 4 of 7 patients with SLL (57%) had ORs, including 3 (43%) with CR/CRu. Rituximab-naive patients (N = 34) had an OR rate of 50% (26% CR/CRu rate), whereas patients who previously responded to rituximab (N = 14) had an OR rate of 64% (29% CR/CRu rate). An OR rate of 85% was observed in patients with FL who had Follicular Lymphoma International Prognostic Index (FLIPI) risk scores of 0 or 1 (N = 13), whereas 28 patients with intermediate or high-risk FLIPI scores (> or =2) had an OR rate of 39% (18% CR/CRu rate). In patients with FL, the median response duration was 13.4 months, and that duration increased to 29.1 months for 10 patients who had a CR/CRu, including 4 patients who had durable responses with remissions that continued for >4 years. In patients with SLL, the median response duration was 20 months, including 1 patient who had a response that continued for >3 years.

Conclusions: The combination of epratuzumab and rituximab induced durable responses in patients with recurrent, indolent NHL.