Pomalidomide plus low-dose dexamethasone in myeloma refractory to both bortezomib and lenalidomide: comparison of 2 dosing strategies in dual-refractory disease.

Pomalidomide at doses of 2 or 4 mg/d has demonstrated excellent activity in patients with multiple myeloma (MM). We opened 2 sequential phase 2 trials using the pomalidomide with weekly dexamethasone (Pom/dex) regimen at differing doses to study the efficacy of this regimen in patients who have failed both lenalidomide and bortezomib. Pomalidomide was given orally 2 or 4 mg daily with dexamethasone 40 mg weekly. Thirty-five patients were enrolled in each cohort. Confirmed responses in the 2-mg cohort consisted of very good partial response (VGPR) in 5 (14%), partial response (PR) in 4 (11%), minor response (MR) in 8 (23%) for an overall response rate of 49%. In the 4-mg cohort, confirmed responses consisted of complete response (CR) in 1 (3%), VGPR in 3 (9%), PR in 6 (17%), MR in 5 (14%) for an overall response rate of 43%. Overall survival at 6 months is 78% and 67% in the 2- and 4-mg cohort, respectively. Myelosuppression was the most common toxicity. This nonrandomized data suggests no advantage for 4 mg over the 2 mg daily. Pomalidomide overcomes resistance in myeloma refractory to both lenalidomide and bortezomib. This trial is registered at http://ClinicalTrials.gov, number NCT00558896.