Open-label pilot study of romiplostim for thrombocytopenia after autologous hematopoietic cell transplantation.

There are no standard treatments to prevent or hasten the recovery from severe conditioning-regimen-induced thrombocytopenia occurring after autologous hematopoietic cell transplantation (auto-HCT). We conducted an open-label, single-arm pilot study of romiplostim, a thrombopoietin receptor agonist, to enhance platelet recovery in patients with multiple myeloma or lymphoma undergoing auto-HCT. All patients were treated weekly with romiplostim starting day +1 after auto-HCT until the platelet count was >50 × 109/L without transfusion. Compared with contemporary retrospective data from romiplostim-naïve patients (N = 853), romiplostim-treated patients (N = 59) had a similar median number of days of grade 4 thrombocytopenia or days requiring transfusions, time to platelet engraftment, and number of platelets transfusions during the auto-HCT. However, romiplostim-treated patients had enhanced platelet recovery to normal values beginning at approximately day +15. In matched cohort multivariable analyses, romiplostim treatment was associated with higher platelet counts by an average of 40 × 109/L (95% confidence interval (CI) (14, 67), P = .003) and 118 × 109/L (95% CI [84, 152], P<.001) at days +21 and +30, respectively, compared with those of no romiplostim. Only 1 adverse event was deemed possibly attributable to romiplostim: a low-risk pulmonary embolism in a patient with multiple myeloma. In conclusion, romiplostim showed promising activity and safety after auto-HCT, but the improvement in platelet counts occurred later than the goal of shortening the duration and depth of the platelet nadir. This trial was registered at www.clinicaltrials.gov (#NCT04478123).

Romiplostim for chemotherapy-induced thrombocytopenia: Efficacy and safety of extended use.

Background: Chemotherapy-induced thrombocytopenia (CIT) is common during treatment with antineoplastic therapies and may adversely impact chemotherapy dose intensity. There is no approved therapy for CIT. In our recent phase II randomized study, romiplostim led to correction of platelet counts in 85% of treated patients and allowed resumption of chemotherapy, with low rates of recurrent CIT in the first two cycles or 8 weeks of chemotherapy. However, there is a lack of long-term data on the efficacy and safety of romiplostim in CIT. Objectives: To analyze efficacy and safety of romiplostim in the patients in the phase 2 study, who received romiplostim for ≥1 year. Patients/Methods: Twenty-one patients remained on romiplostim for ≥1 year. We analyzed the effect of romiplostim on platelet counts, absolute neutrophil counts, and hemoglobin, as well as impact on ongoing chemotherapy. We also tracked venous or arterial thrombotic events. Results: During the study period, romiplostim was effective in preventing reduction of chemotherapy dose intensity due to CIT. Fourteen of the 20 (70%) analyzable patients experienced no episode of CIT, 4 subjects experienced a single chemotherapy dose delay due CIT, and 2 patients required a chemotherapy dose reduction. Platelet counts were preserved throughout the duration of the extension analysis. One patient experienced a proximal deep vein thrombosis, and one patient experienced multiple tumor-related ischemic events. Conclusions: Long-term use of romiplostim for treatment of CIT was effective and safe, with no evidence of resistance or increased risk of thrombosis.