[Maintenance of efficacy and its predictors after discontinuation of eltrombopag in adults with primary immune thrombocytopenia].

Objective: To determine the efficacy of eltrombopag for primary immune thrombocytopenia (ITP) in adults and the predictive factors for treatment-free response (TFR) . Methods: Clinical data of adults with ITP who received eltrombopag from June 14, 2013 to May 31, 2021 in the Hematology Department of Ruijin Hospital affiliated with Shanghai Jiao Tong University Medical College were retrospectively analyzed. The initial dose of eltrombopag was 25 mg/d, and the maximum dose was 75 mg/d; the dose was adjusted to maintain the platelet count to within 50-150×10(9)/L. Treatment was discontinued according either to the protocol, on the patient's wishes or doctor's judgment (prescription medication), or based on clinical trials. The efficacy of eltrombopag and factors for TFR among patients who achieved complete response and those who discontinued treatment were analyzed. Results: Overall, 106 patients with ITP (33 men and 73 women) were included in the study. The median age of patients was 50 (18-89) years. There were 2, 10, and 94 cases of newly diagnosed, persistent, and chronic ITP, respectively. The complete response rate was 44.3% (47/106), the response rate was 34.0% (36/106), and the overall response rate was 78.3% (83/106). Meanwhile, 83 patients who responded to treatment discontinued eltrombopag; of these, 81 patients were evaluated. Additionally, 17 patients (21.0%) achieved TFR. The median follow-up duration of patients who achieved TFR was 126 (30-170) weeks. The recurrence rate was 17.6% (3/17), and the relapse-free survival rate was 76.5%. The results of univariate analysis revealed that non-recurrence after discontinuation of other treatments for ITP ( P =0.001), and platelet count and eltrombopag dose of ≥100×10(9)/L ( P =0.007) and ≤25 mg/d ( P =0.031), respectively, upon discontinuation of eltrombopag were predictors of TFR; these effects were attributed to prolonged effective duration of eltrombopag. Multivariate analysis showed that there was a correlation between non-recurrence and prolonged effective duration after discontinuation of other treatments for ITP ( P =0.002) . Conclusion: Eltrombopag is effective for patients with ITP as it can result in TFR. Predictors for TFR include non-recurrence after discontinuation of concomitant ITP treatment, and platelet count and eltrombopag dose of ≥100 × 10(9)/L and ≤25 mg/d upon discontinuation of treatment, respectively.