Combination of Bortezomib, Melphalan, Prednisone and Thalidomide (VMPT) for Relapsed Multiple Myeloma: Results of a Phase I/II Clinical Trial.

BACKGROUND: In newly diagnosed patients, the addition of thalidomide or bortezomib (Velcade™) to the standard oral melphalan/prednisone combination significantly increased response rate and event-free survival. In this multicenter, open-label, non randomized, phase I/II trial, the safety/efficacy profile of the 4 drug combination, bortezomib (Velcade™), melphalan, prednisone, and thalidomide (VMPT) was evaluated in patients with relapsed/refractory myeloma.

METHODS: Bortezomib was administered by IV bolus on days 1, 4, 15, 22 at three dose levels: in the first cohort (10 patients) at 1.0 mg/m²; in the second cohort (10 patients) at 1.3 mg/m²and in the third cohort (10 patients) at 1.6 mg/m². Oral melphalan was administered at 6 mg/m² on days 1–5, oral prednisone at 60 mg/m² on days 1–5. Thalidomide was delivered at 50 mg on days 1–35. Each course was repeated every 35 days for a total of 6 courses.

RESULTS: Thirty patients, median age 66 years (range 38–79), with relapsed or refractory myeloma were enrolled. Fourteen patients received VMPT as second line of therapy, 16 as third line. Twenty patients received prior autologous transplant, 10 conventional chemotherapy and 9 thalidomide-based regimens. After a median of 6 courses, 20 patients (67%) achieved a partial response (PR) including 13 patients (43%) who achieved at least a very good partial response (VGPR). Among patients who received VMPT as second line treatment, the PR rate was 79%, and the immunofixation negative complete response rate 36%. The 1-year progression-free survival was 61%, and the 1-year survival from study entry was 84%. Grade 3 non-hematological adverse events included: infections (5 patients), fatigue (1), vasculitis (1) and peripheral neuropathy (2); no grade 4 toxicities were recorded.

CONCLUSIONS: Initial results showed that VMPT is an effective salvage therapy with a high proportion of responses. Toxicities were manageable. The incidence of neurotoxicities was unexpectedly low.