Safety and efficacy of hetrombopag in patients with chronic immune thrombocytopenia: a single-arm, open-label, multi-center phase 1 study

BACKGROUND: Thrombopoietin receptor agonists (TPO‐RAs) are promising therapeutic strategy for patients with immune thrombocytopenia (ITP). We conducted this phase 1 trial (NCT02614846) to evaluate the preliminary efficacy and safety of hetrombopag (a TPO-RA) in patients with ITP. METHODS: Patients with ITP who had an insufficient response or had progressed on at least one standard treatment for ITP were given hetrombopag orally at an initial dose of 5 mg once daily for up to 6 weeks. The primary endpoint was the proportion of patients who achieved platelet counts of ≥50×10(9)/L at week 6. RESULTS: A total of 37 eligible patients received hetrombopag treatment. This study met its primary endpoint, 22 (59.5%, 95% CI: 42.1–75.3) patients responded to hetrombopag, achieving platelet counts ≥50×10(9)/L at week 6. Of the 29 (78.4%, 95% CI: 61.8–90.2%) patients who responded at least once during the study, the median time from treatment initiation to first response was 2.1 weeks (95% CI: 1.3–4.1 weeks). The median accumulative response duration was 3.1 weeks [interquartile range (IQR), 2.1–4.1 weeks]. The incidence of bleeding was reduced with hetrombopag treatment compared to the baseline. Adverse events (AEs) occurred in 32 (86.5%) patients and treatment-related AEs occurred in 13 (35.1%) patients. Two (5.4%) serious AEs were reported, but neither were treatment related. The dose was modified in one (2.7%) patient due to an AE. There were no incidences of treatment discontinuation/interruption or death. CONCLUSIONS: Hetrombopag showed preliminary activity in elevating platelet counts and reducing bleeding in patients with chronic ITP who had received at least one standard therapy. It was well-tolerated.