Abstract
Background: Cancer therapy-induced thrombocytopenia (CTIT) is a common hematologic toxicity for patients with breast cancer (BC) causing anti-cancer therapy delays, dose reductions, and discontinuation. As a novel oral thrombopoietin-receptor agonist (TPO-RA), hetrombopag might raise platelets in patients with CTIT. We carried out a prospective, single-arm trial to assess the efficacy and safety of hetrombopag monotherapy in CTIT among patients with BC (ChiCTR2200062811). Methods: Thrombocytopenic patients with BC (Age ≥18 years, platelet counts<75×109/L) caused by anti-tumor treatments were eligible. The enrolled patients received hetrombopag monotherapy (5.0mg, qd) until reaching a recovery in PLT ≥ 80×10 9 /L or an increase of ≥50×109/L compared to the baseline. The treatment would stop when patients accepted 14 consecutive days of treatment or reached the discontinuation criteria. Platelet examination was taken every 3 days during the study period. The daily blood test was required if the baseline platelet counts <50×109 /L. The primary endpoint was platelet response within 14 days, denoted by a recovery in PLT ≥75×109/L compared to the baseline. The secondary endpoints included the proportion of patients with platelets recovered to ≥ 100×10 9 /L, the proportion of patients with platelet transfusion, the incidence of dose reduction, delay, or discontinuation of consecutive cancer therapy cycles, and the safety. Results: From January 1, 2024, to June 30, 2024, 19 patients were screened for eligibility. The baseline characteristics were as follows: The median age was 51, with the majority (89.5%,17/19) at clinical stage IV. All patients with BC were treated with different anti-tumor regimens (31.6% (6/19) with chemotherapy therapy only, 21.1% (4/19) with antibody-drug conjugate (ADC) therapy, 15.8% (3/19) with chemotherapy plus targeted therapy, 15.8% (3/19) with endocrine therapy plus targeted therapy, 5.3% (1/19) with chemotherapy plus PD-1 inhibitors, 5.3% (1/19) with chemotherapy plus PD-1 inhibitor and antiangiogenic agent, 5.3% (1/19) with ADC plus antiangiogenic agent). Among them, 42.1% (8/19) of patients have received ≥3 lines of therapy. The median time from the last anti-tumor treatment to meet the inclusion requirement was 7 days (range, 1-22 days). The median value of baseline platelet counts was 65×10 9 /L (range, 28-74×10 9 /L). All patients experiencing ≥ grade 2 thrombocytopenia (PLT<75×10 9/L) after anti-tumor received hetrombopag monotherapy 5.0mg/day. Among them, 10.5% (2/19) experienced grade 3 thrombocytopenia. Treatment response was 89.5% (17/19), with a median time of 3 days (range, 3-9 days) to respond. The proportion of patients with platelets recovered to ≥100×109/L was 68.4% (13/19), with a median time of 6 days (range, 3-6 days) to respond. The incidence of dose reduction and delay of consecutive planned chemotherapy cycles were 18.8% (3/16, 3 patients had changed treatments due to disease progression or turning into maintenance therapy) and 42.1% (8/19), respectively. Especially, the platelet counts of 2 patients with severe thrombocytopenia (PLTs were 28×109/L and 39×109/L at baseline, respectively) increased to ≥100 × 109/L in 6 days after hetrombopag treatment. For safety, during the treatment of herombopag, there were 15.8% (3/19), 10.5% (2/19), and 5.3% (1/19) experienced grade 3-4 white blood cell count decreasing, neutrophil count decreasing, and anemia, respectively. No thrombosis was observed. There were no ≥ grade 3 increased AST and/or ALT. Conclusion: In this study, hetrombopag monotherapy is efficacious and well tolerated, substantiating its potential role as a novel treatment strategy for CTIT patients with breast cancer.
Citation Format: Hanfang Jiang, Anjie Zhu, Huiping Li, Yaxin Liu, Ran Ran, Guohong Song, Bin Shao, Jiayang Zhang, Nan Wang. Prospective phase II study on the efficacy and safety of hetrombopag for the treatment of cancer therapy-induced thrombocytopenia in patients with breast cancer [abstract]. In: Proceedings of the San Antonio Breast Cancer Symposium 2024; 2024 Dec 10-13; San Antonio, TX. Philadelphia (PA): AACR; Clin Cancer Res 2025;31(12 Suppl):Abstract nr P1-02-12.
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