Phase 2 study of romiplostim in patients with low- or intermediate-risk myelodysplastic syndrome receiving azacitidine therapy

We evaluated the efficacy and safety of romiplostim, a thrombopoietin mimetic, in patients with low- or intermediate-risk myelodysplastic syndromes (MDS) receiving azacitidine therapy. Forty patients with low- or intermediate-risk MDS were stratified by baseline platelet counts (< 50 vs ≥ 50 × 10 ⁹/L) and randomized to romiplostim 500 μg or 750 μg or placebo subcutaneously once weekly during 4 cycles of azacitidine. The primary endpoint was the incidence of clinically significant thrombocytopenic events, defined by grade 3 or 4 thrombocytopenia starting on day 15 of the first cycle or platelet transfusion at any time during the 4-cycle treatment period. No formal hypothesis testing was planned. The incidence of clinically signifi-cant thrombocytopenic events in patients receiving romiplostim 500 μg, romiplostim 750 μg, or placebo was 62%, 71%, and 85%, respectively. The incidence of platelet transfusions was 46%, 36%, and 69%, respectively. These differences were not statistically significant with the small numbers in each group. Romiplostim 750 μg significantly raised median platelet counts during cycle 3 on day 1 (P = .0373) and at the nadir (P = .0035) compared with placebo. Grade 3 rash and arthralgia each were reported in 1 romiplostim-treated patient (4%). This study suggests romiplostim may provide clinical benefits in MDS patients during azacitidine therapy. This study was registered at www.clinicaltrials.gov as #NCT00321711.