Aplastic anemia (AA) secondary to radiotherapy presents a difficult situation in the treatment of both the malignant tumor and AA itself. We aimed to evaluate the efficacy of avatrombopag (AVA), a thrombopoietin receptor agonist, in patients with AA secondary to chemoradiotherapy. In this retrospective study, patients with malignant tumors who were diagnosed with AA after radiotherapy and chemotherapy and accepted AVA between September 2020 and October 2021 at Peking Union Medical College Hospital were selected. A total of 34 patients were enrolled, including 13 (38.2%) men, with a median age of 60 (20-71) years. At a median of 8 (6-18) months of follow-up, the overall response rates (ORRs) at 1, 3, and 6 months were 32.4%, 55.9%, and 58.8%, respectively, and the complete response rates (CRRs) were 5.9%, 14.7%, and 23.5%, respectively. The median time to respond was 3 (1-6) months. In total, 15.0% of patients relapsed during follow-up, but no clonal evolution was noticed. Mild side effects were observed in 17.6% of patients without drug withdrawal. At the end of follow-up, 17.6% of patients had tumors relapsed. Four patients died, three from tumor relapse and one from cerebral hemorrhage. The ORR and CRR did not correlate with eltrombopag before AVA (p > 0.05) but increased when the total exposure of AVA increased (p = 0.011), and the threshold for AVA response was a cumulative dose > 3,000 mg (p = 0.013). AVA yielded good response and tolerance in patients treated for AA secondary to chemoradiotherapy, and a higher dose may correlate with better response.
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