Objective: This study aimed at investigating the efficacy and safety of
eltrombopag in the treatment of adult primary
immune thrombocytopenia (
ITP) and evaluated the factors influencing its efficacy and side effects. Methods: A total of 198 patients with adult
ITP who were admitted to Tianjin Medical University General Hospital between January 2018 and March 2022 were retrospectively analyzed. The efficacy of each starting dose of
eltrombopag was evaluated, and adverse events were analyzed. The factors influencing efficacy were investigated, including sex, age, adult
ITP type, platelet
antibodies, and combined drug treatments. Results: Of the 198 patients, 70 males and 128 females with a median age of 45 years (18-88 years) were included; 130 (65.7%) had newly diagnosed adult
ITP, 25 (12.6%) had persistent adult
ITP, and 43 (21.7%) had chronic adult
ITP. The
bleeding event scores at baseline were assessed; 84.3% had scores of<4 and 15.7% had scores of ≥4. The
eltrombopag response rate (initial response) at 6 weeks was 78.8% (complete response [CR]: 49.0%; CR1: 14.6%; CR2: 15.2%). The median response time to
eltrombopag was 7 (7, 14) days. The initial response rates to 25, 50, and 75 mg
eltrombopag were 74.1%, 85.9%, and 60.0%, respectively (P=0.031). The initial response rate to the 50 mg dose was significantly higher than that of the 25-mg and 75-mg doses. Two patients received 100 mg as the starting dose, and their initial response was 0. Regarding dose adjustment, 70.7% of the patients remained on the starting dose, 8.6% underwent dose adjustment to 50 mg, and 6.1% underwent dose adjustment to 75 mg. Another two patients underwent dose adjustment to 100 mg. After dose adjustment, the persistent response rates were 83.6%, 85.3%, and 85.7% for the 25-, 50-, and 75-mg doses, respectively, with no significant difference. After dose adjustment, the sustained efficacy rate for the 100-mg dose (4 patients) was 100.0%. After 6 weeks of treatment with
eltrombopag, the overall
bleeding score of patients with
ITP decreased. The number of patients with a score of ≥4 decreased to 0, the number of patients with a score of<4 decreased, and there was no significant change in the number of patients with a score of 1-2. The most common adverse event associated with
eltrombopag was impaired liver function (7.7%). No
thrombosis events or other adverse events were observed.
ITP type and number of megakaryocytes significantly affected the initial response to
eltrombopag. The initial response rates to
eltrombopag for newly diagnosed adult
ITP, persistent adult
ITP, and chronic adult
ITP were 85.3%, 56.0%, and 76.2%, respectively (P=0.003). For megakaryocytes, the initial response rates were 61.8%, 87.1%, and 84.3% (P=0.009) for the decreased, normal, and increased megakaryocyte groups, respectively. Conclusion:
Eltrombopag, as a second-line or higher treatment for adult
ITP, has a rapid onset of action and good safety. The initial response rate is significantly higher with a dose of 50 mg than with a dose of 25 mg. Patients with newly diagnosed
ITP and those with normal or increased megakaryocyte numbers have a higher initial response rate to
eltrombopag.