Interim results of a phase II study (EQOL-MDS) reported in the Journal of Clinical Oncology by Oliva et al showed that eltrombopag, an orally bioavailable small molecule acting as a thrombopoietin receptor agonist, significantly increased the rate of platelet response vs placebo in patients with low-risk myelodysplastic syndrome (MDS) and severe thrombocytopenia.
Study Details
In the international trial, 169 patients with International Prognostic Scoring System low- or intermediate-1–risk MDS with a stable platelet count of less than 30 x 103/mm3 were randomly assigned 2:1 between 2011 and 2021 to receive oral eltrombopag at a starting dose of 50 mg once daily to a maximum of 300 mg once daily (n = 112) or placebo (n = 57) until disease progression. The primary efficacy endpoint was duration of platelet response calculated as the time from platelet response to the date of loss of platelet response, defined as bleeding/platelet count less than 30 x 103/mm3 or the last date in observation.
Key Findings
With a median follow-up of 25 weeks (interquartile range = 14–68 weeks), platelet response was observed in 47 of 111 evaluable patients (42.3%) in the eltrombopag group vs 6 of 54 evaluable patients (11.1%) in the placebo group (odds ratio = 5.9, 95% confidence interval [CI] = 2.3–14.9, P < .001).
Median duration of platelet response was not reached among responders in either group. At data cutoff with an observation period of 13 to 561 weeks, 12 of the 47 responders (25.5%) in the eltrombopag group had lost platelet response, with a cumulative thrombocytopenia relapse-free survival at 60 months of 63.6% (95% CI = 46.0%–81.2%). With an observation period of 83 to 398 weeks, all six responders in the placebo group maintained response until study termination. No difference in response duration was observed (P = .14).
Clinically significant bleeding occurred in 19.8% of patients in the eltrombopag group vs 31.5% of the placebo group (incidence rate ratio = 0.54, 95% CI = 0.38–0.75, P = .0002). No difference in the exposure-adjusted incidence rate of grade 1 or 2 adverse events was observed between groups (P = .868). Grade 3 or 4 nonhematologic adverse events were significantly more common in the eltrombopag group (exposure-adjusted incidence rate of 2.5 vs 1.6 events per 100 person-months, P = .002). The combined outcome of acute myeloid leukemia evolution or disease progression occurred in 17% of patients both in the eltrombopag group and in the placebo group.
The investigators concluded: “Eltrombopag was effective and relatively safe in low-risk MDS with severe thrombocytopenia.”
Esther Natalie Oliva, MD, of Grande Ospedale Metropolitano Bianchi Melacrino Morelli, Reggio Calabria, Italy, is the corresponding author of the Journal of Clinical Oncology article.
Disclosure: The study was funded by Associazione QOL-ONE, Novartis, and others. For full disclosures of the study authors, visit ascopubs.org.
