Eltrombopag, a small molecule acting as a thrombopoietin receptor (TPO-R) agonist, is effective in patients with low-risk myelodysplastic syndrome (MDS) with severe thrombocytopenia, according to a study published in the Journal of Clinical Oncology. Interim study results showed it also has an acceptable safety profile.
Preliminary studies indicated that eltrombopag may have a role in treating patients with low-risk MDS and long-term thrombocytopenia. The authors of the study sought to conduct a trial to assess the merits of eltrombopag in ameliorating severe thrombocytopenia in MDS.
THE EQOL-MDS study (ClinicalTrials.gov Identifier: NCT02912208) is a multicenter, single-blind, placebo-controlled trial. The research team included adult patients with low-to-intermediate risk MDS with a stable platelet count. Among the exclusion criteria was previous treatment with TPO-R agonists.
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Participants were randomly assigned in a 2:1 ratio to either receive eltrombopag (n=112) or placebo (n=57). Patients who received eltrombopag were administered an initial dose of 50 mg once daily, followed by 50 mg increments every 2 weeks until a dose of 300 mg is reached.
The researchers conducted peripheral blood and bone marrow assessments at baseline and at predetermined times during the study. In addition, they assessed changes in quality of life as determined via the filling in of a questionnaire.
Endpoints of the trial included short- and long-term efficacy of eltrombopag, as well as its safety and tolerability profile. The research team also assessed parameters such as frequency of platelet transfusions needed, duration of transfusion independence, and progression-free survival.
A total of 169 patients participated in the study; 112 received eltrombopag and 57 were assigned the placebo. The researchers reported that eltrombopag was safe and well-tolerated among participants receiving the drug; importantly, a complete platelet response (defined according to the International Working Group 2006 criteria) was observed only among participants who received eltrombopag (27.9%).
Of the 47 patients receiving eltrombopag who achieved a stable platelet count, 31 (66.0%) showed a complete response, compared with 6 patients in the placebo group (odds ratio, 5.9; 95% CI, 2.3-14.9; P <.001). At the time of data cutoff, 16 of 47 (34.0%) responsive patients in the eltrombopag arm continued to have responses to treatment vs 1 of 6 (16.6%) responsive patients in the placebo arm.
For patients in the eltrombopag arm, 12 of 47 (25.5%) lost stable platelet count with a cumulative thrombocytopenia relapse-free survival at 60 months of 63.6% (95% CI, 46.0-81.2). In the placebo arm, the 6 responders maintained stable platelet count until study termination with 1 patient remaining on the study after 76 months of response.
Furthermore, the platelet response achieved was “durable and stable,” according to the authors of the study. The research team also found that a dose of 50 mg once daily was not only sufficient to obtain a platelet response, but that the median time needed to achieve this was shorter than expected.
In terms of safety, 62 patients in the eltrombopag arm and 29 in the placebo arm experienced grade 1-2 adverse events (AEs), with no statistically significant difference between the arms. Notably, 18 patients on the eltrombopag arm required permanent treatment discontinuation due to severe liver or persistent grade 3-4 AEs, with no patients in the placebo arm requiring the same.
“In conclusion, eltrombopag has an acceptable toxicity profile and is effective in raising and maintaining [platelet] count and reducing bleeding without any associated risk of MDS progression,” the study authors wrote in their report.
Reference
Oliva EN, Riva M, Niscola P, et al. Eltrombopag for low-risk myelodysplastic syndromes with thrombocytopenia: interim results of a phase-II, randomized, placebo-controlled clinical trial (EQOL-MDS). J Clin Oncol. Published online June 9, 2023. doi:10.1200/JCO.22.02699
