Hetrombopag for the Management of Chemotherapy-induced Thrombocytopenia in Patients with Advanced Solid Tumors: a Multicenter, Randomized, Double-blind, Placebo-controlled, Phase II Study

Background: Chemotherapy-induced thrombocytopenia (CIT) increases the risk of bleeding, necessitates chemotherapy dose reductions and delays, and negatively impacts prognosis.

Objectives: This study aimed to evaluate the efficacy and safety of hetrombopag for the management of CIT in patients with advanced solid tumors.

Design: A multicenter, randomized, double-blind, placebo-controlled, phase II study.

Methods: Patients with advanced solid tumors who experienced a chemotherapy delay of ⩾7 days due to thrombocytopenia (platelet count <75 × 10/L) were randomly assigned (1:1) to receive oral hetrombopag at an initial dose of 7.5 mg once daily or a matching placebo. The primary endpoint was the proportion of treatment responders, defined as patients resuming chemotherapy within 14 days (platelet count ⩾100 × 10/L) and not requiring a chemotherapy dose reduction of ⩾15% or a delay of ⩾4 days or rescue therapy for two consecutive cycles.

Results: Between 9 October 2021 and 5 May 2022, 60 patients were randomized, with 59 receiving ⩾1 dose of assigned treatment (hetrombopag/placebo arm,  = 28/31). The proportion of treatment responders was significantly higher in the hetrombopag arm than in the placebo arm [60.7% (17/28) 12.9% (4/31); difference of proportion: 47.6% (95% confidence interval (CI): 26.0-69.3); odds ratio = 10.44 (95% CI: 2.82-38.65); value (nominal) based on the Cochran-Mantel-Haenszel: <0.001)]. During the double-blind treatment period, grade 3 or higher adverse events (AEs) occurred in 35.7% (10/28) of patients with hetrombopag and 38.7% (12/31) of patients on placebo. The most common grade 3 or higher AEs were decreased neutrophil count [35.7% (10/28) 35.5% (11/31)] and decreased white blood cell count [17.9% (5/28) 19.4% (6/31)]. Serious AEs were reported in 3.6% (1/28) of patients with hetrombopag and 9.7% (3/31) of patients with placebo.

Conclusion: Hetrombopag is an effective and well-tolerated alternative for managing CIT in patients with solid tumors.

Trial Registration: ClinicalTrials.gov identifier: NCT03976882.