Initial blood counts provide the best predictors of response to immunosuppressive therapy (IST) plus eltrombopag (EPAG) for patients with severe aplastic anemia (SAA), according to research published in Haematologica.
EPAG is a synthetic thrombopoietin receptor antagonist that has been found to improve outcomes compared to IST alone. This is the standard nontransplant treatment for SAA.
The single-center retrospective study sought to determine whether predictors of response to IST were also associated with response to IST plus EPAG. The authors also aimed to identify subgroups of patients who may benefit from the combination treatment.
A total of 176 patients aged 2 to 82 years treated with IST plus EPAG at the National Institutes of Health Clinical Center were included and were compared to 240 patients treated with IST alone.
IST plus EPAG had an overall response (OR) of 82% compared to 62% with IST alone (P <.0001) and a complete response (CR) of 39% vs 13% (P <.0001).
Patients who responded to IST plus EPAG had higher absolute reticulocyte count (ARC), absolute neutrophil count (ANC), and absolute lymphocyte count (ALC) before therapy than patients who did not respond. Patients with higher blood counts also responded better to IST alone.
Patients with an ARC of at least 10×109 /L before treatment had an OR of more than 91% when treated with IST and EPAG. In contrast, the OR for patients treated with IST alone is improved with pretreatment ARC of at least 30×109/L.
Baseline blood counts were not predictive of CR in patients treated with EPAG plus IST, although there was an age-based association. CR was associated with lower ALC in children younger than 10 years and with a higher ALC in adolescents and adults.
Based on these results, baseline blood counts are the best predictor of response to nontransplant therapies for SA. Patients with ANC between 10-30×109/L have better prognosis with IST plus EPAG.
Zaimoku Y, Patel BA, Shalhoub R, et al. Predicting response of severe aplastic anemia to immunosuppression combined with eltrombopag. Haematologica. Published online April 29, 2021. doi:10.3324/haematol.2021.278413