The thrombopoietic agent eltrombopag (Promacta) did more harm than good when given to adults with acute myeloid leukemia (AML) during standard induction chemotherapy, results of a randomized phase 2 trial show.
Patients who were randomly assigned to receive standard induction chemotherapy with daunorubicin and cytarabine plus eltrombopag had a higher incidence of serious adverse events and death from hemorrhage within 30 days of the last eltrombopag dose, compared with patients who received chemotherapy and placebo, reported Noelle Frey, MD, from the University of Pennsylvania in Philadelphia, and colleagues.
“Overall survival was also numerically longer in the placebo group, compared with the eltrombopag group. It remains unclear why there were more deaths, particularly due to hemorrhage within 30 days after the last dose of treatment, in the eltrombopag group,” they wrote in the Lancet Haematology.
The investigators had expected better results, based on eltrombopag’s demonstrated efficacy against thrombocytopenia (a common feature of AML, exacerbated by chemotherapy), and because of evidence suggesting that the thrombopoietin-receptor agonist might also have antileukemic properties.
They set out to test the safety, tolerability, and efficacy of eltrombopag added to standard induction therapy in patients with treatment-naive AML of any subtype except M3 (acute promyelocytic leukemia) or M7 (acute megakaryocytic leukemia).
Patients received chemotherapy with daunorubicin in a bolus intravenous infusion at a dose of 90 mg/m2 on days 1-3 for patients 18-60 years of age, or 60 mg/m2 for patients older than 60 years, plus cytarabine continuous intravenous infusion at a dose of 100 mg/m2 on days 1-7. The 148 patients were randomized in groups of 74 each to receive either eltrombopag 200 mg (100 mg for patients of east Asian heritage) or placebo, once daily.
Eltrombopag was continued until platelet counts were 200 × 109/L or higher, remission, or 42 days after the start of induction chemotherapy.
Grade 3 or 4 adverse events occurring in 10% or more of patients – a primary endpoint – were febrile neutropenia, which occurred in 42% of patients receiving eltrombopag, compared with 39% receiving placebo, decreased white blood cell count in 11% vs. 7%, and hypophosphatemia in 4% and 13%, respectively,
Serious adverse events occurred in 34% of patients on eltrombopag, compared with 20% on placebo. Similarly, 53% of patients receiving eltrombopag died, compared with 41% of patients receiving the placebo.
Most of the deaths were attributable to AML, including 19 patients (26%) on eltrombopag and 10 (14%) on placebo. Eleven patients on eltrombopag and four on placebo died within 30 days of the last dose of study treatment.
Hemorrhage accounted for the deaths of five patients on eltrombopag and three on placebo, and sepsis accounted for the deaths of five and six patients, respectively.
Both the incidence of thromboembolic events and mean change in left ventricular ejection fraction were similar between the groups.
Median overall survival was 15.4 months in the eltrombopag group vs. 25.7 months in the placebo group, although this difference was not statistically significant, likely because of the sample size.
The investigators were at a loss to explain why the eltrombopag-treated patients had numerically worse outcomes.
“In the present study, eltrombopag did not improve the time to platelet recovery or the incidences of grade 3-4 thrombocytopenia, neutropenia, or anemia, compared with placebo. Furthermore, the study did not reveal any differences in investigator-assessed response to treatment. These findings were unexpected given outcomes from previous studies of eltrombopag monotherapy in patients with myelodysplastic syndromes or acute myeloid leukemia,” they wrote.
Although the reasons behind the findings are unclear, “the data from this trial do not support a favorable benefit-risk profile for eltrombopag in combination with induction chemotherapy in patients with acute myeloid leukemia,” the investigators wrote.
The study was funded by Novartis. Dr. Frey reported nonfinancial support from Novartis during the conduct of the study and consultancy fees from Novartis outside of the submitted work. Multiple coauthors reported similar relationships with Novartis and/or other companies.
SOURCE: Frey N et al. Lancet Haematol. 2019 Jan 28. doi: 10.1016/S2352-3026(18)30231-X.