Pomalidomide, bortezomib, and dexamethasone for patients with relapsed lenalidomide-refractory multiple myeloma

This phase 1/2 trial evaluated the maximum tolerated doses, safety, and efficacy of pomalidomide, bortezomib, and dexamethasone (PVD) combination in patients with relapsed lenalidomide-refractory multiple myeloma (MM). In phase 1, dose level 1 consisted of pomalidomide (4 mg by mouth on days 1 to 21), IV or subcutaneous bortezomib (1.0 mg/m² on days 1, 8, 15, and 22), and dexamethasone (40 mg by mouth on days 1, 8, 15, and 22) given every 28 days. Bortezomib was increased to 1.3 mg/m² for dose level 2 and adopted in the phase 2 expansion cohort. We describe the results of 50 patients. Objective response rate was 86% (95% confidence interval [CI], 73-94) among all evaluable patients (stringent complete response, 12%; complete response, 10%; very good partial response, 28%; and partial response, 36%) and 100% among high-risk patients. Within a median follow-up of 42 months, 20% remain progression free, 66% are alive, and 4% remain on treatment. Median progression-free survival was 13.7 months (95% CI, 9.6-17.7). The most common toxicities were neutropenia (96%), leukopenia (84%), thrombocytopenia (82%), anemia (74%), and fatigue (72%); however, the majority of these were grade 1 or 2. The most common grade ≥3 toxicities included neutropenia (70%), leukopenia (36%), and lymphopenia (20%). Deep vein thrombosis occurred in 5 patients. In conclusion, PVD is a highly effective combination in lenalidomide-refractory MM patients. Weekly administration of bortezomib enhanced tolerability and convenience. Toxicities are manageable, mostly consisting of mild cytopenias with no significant neuropathy. This trial was registered at www.clinicaltrials.gov as #NCT01212952.