Long-term results of the phase II trial of the oral mTOR inhibitor everolimus (RAD001) in relapsed or refractory Waldenstrom Macroglobulinemia.

Everolimus is an oral raptor mTOR inhibitor and has shown activity in patients with Waldenstrom's macroglobulinemia (WM). This study examines a large cohort of patients with relapsed/refractory WM with long-term follow up for survival. Patients were eligible if they had measurable disease, a platelet count >75,000 x 10(6)/L, an absolute neutrophil count >1,000 x 10(6)/L. Patients received everolimus 10 mg PO daily and were evaluated monthly. A success was defined as a complete or partial response (PR); minor responses (MR) were recorded and considered to be of clinical benefit. Sixty patients were enrolled and treated. The overall response rate (ORR) was 50% (all PR); the clinical benefit rate including MR or better was 73% (95% CI: 60-84%) with 23% MR. The median time to response for patients who achieved PR was 2 months (range, 1-26). The median duration of response has not been reached and median progression-free survival (PFS) was 21 months. Grade 3 or higher toxicities (at least possibly related to everolimus) were observed in 67% of patients. The most common grade 3 or 4 toxicities were anemia (27%), leukopenia (22%), and thrombocytopenia (20%). Other nonhematological toxicities were diarrhea (5%), fatigue (8%), stomatitis (8%) and pulmonary toxicity (5%). Everolimus has a high single-agent activity of 73% including MR, with a progression free survival of 21 months, indicating that this agent is active in relapsed/refractory WM.