A Prospective Randomized Phase I/II Study of Lenalidomide, Melphalan, Prednisone and Thalidomide (RMPT) for Relapsed/Refractory Multiple Myeloma Patients.

New drug associations may improve patients outcome in relapsed/refractory multiple myeloma (MM). In newly diagnosed MM patients the addition of lenalidomide or thalidomide or bortezomib, to the standard oral melphalan and prednisone combination significantly increased response rate and event-free survival, showing synergistic effects.

This is a multicenter, randomized, open label phase I/II trial designed to evaluate the safety/efficacy profile of the salvage treatment, Lenalidomide, Melphalan, Prednisone and Thalidomide (RMPT) in patients with relapsed/refractory myeloma.

Oral lenalidomide was administered at 10 mg/day on days 1-21, in combination with oral melphalan at 0.18 mg/kg on days 1–4 and oral prednisone at 2 mg/kg on days 1–4. Thalidomide was administered at 50 mg/day (Arm A) or 100 mg/day (Arm B) on days 1-28. Each course was repeated every 28 days for a total of 6 courses. Maintenance therapy included Lenalidomide alone at 10 mg/day on days 1-21. Aspirin 100 mg/day was given as a prophylaxis for thrombosis.

Forthy-four patients with relapsed/refractory MM were enrolled in the study between May 2007 and March 2008, including 22 patients in arm A and 22 patients in arm B. After a median of 5 cycles 75% of patients achieved at least a partial response (PR), including 20% very good partial response (VGPR) and 14% near or complete response (nCR or CR). Among patients who received thalidomide 100 mg, the PR rate was 82% (including 23% VGPR and 23% CR/nCR). Higher response rate was observed among patients who received RMPT in first relapse. The 1-year-progression-free survival was 51,5% and the 1-year survival from study entry was 72%. Hematologic toxicity was the most frequent adverse event. Grade 3-4 hematologic adverse events included: neutropenia (68%), thrombocytopenia (36%) and anemia (32%). Grade 3-4 non hematologic adverse events included: infections (22,7%), neurological toxicity (4,5%) and fatigue (6,8%). No grade 3-4 thromboembolic events were reported.

This is the first trial exploring the association of two immunomodulatory drugs, Thalidomide and Lenalidomide. RMPT is an active regimen in patients with relapsed/refractory MM. Toxicities were manageable and the incidence of neutrotoxcities was low. Updated results will be presented at the time of the meeting.

Cavallo:CELGENE: Honoraria. Petrucci:CELGENE: Honoraria. Canepa:CELGENE: Honoraria. Boccadoro:CELGENE: CONSULTANCY, ADVISORY COMMITTEES, Research Funding. Palumbo:CELGENE: Honoraria.