Prophylactic Recombinant Human Thrombopoietin Prevents Cancer Therapy-Induced Thrombocytopenia During Concurrent Chemoradiation Therapy in Limited-Stage Small Cell Lung Cancer: A Prospective, Multicenter, Phase II Clinical Trial.

Abstract

Concurrent chemoradiation therapy is the standard therapy for limited-stage small cell lung cancer (LS-SCLC) but induces cancer therapy-induced thrombocytopenia (CTIT), which leads to treatment delays. This study aims to assess the efficacy and safety of prophylactic recombinant human thrombopoietin (rhTPO) in preventing CTIT in this patient population. This prospective, multicenter, phase II trial was conducted across 14 Chinese centers. LS-SCLC patients receiving etoposide plus cisplatin or carboplatin chemotherapy with concurrent radiation therapy were given subcutaneous rhTPO (300 IU/kg/d) on days 1-5, 8-12, and 15-19 during radiation therapy. rhTPO treatment was stopped if platelet count reached ≥300 × 10⁹/L or increased by ≥100 × 10⁹/L from baseline. Primary endpoints were the nadir and peak platelet count. From March 8, 2024, to October 10, 2024, 56 LS-SCLC patients were enrolled. During the rhTPO treatment period, nadir platelet count (×10⁹/L) was 128.54 ± 54.15, and peak platelet count reached 409.23 ± 173.50. Overall incidence of CTIT was 33.9% (19/56), including 8.9% (5/56) grade 3, and no grade 4-5 events. A total of 78.9% of patients (15/19) experienced platelet count recovery to ≥100 × 10⁹/L during the rhTPO treatment period. Median time for platelet count recovery from <100 × 10⁹/L to ≥100 × 10⁹/L was 8 days (95% CI, 6-14). Multivariable logistic regression analysis revealed that low baseline platelet count (<150 × 10⁹/L) was an independent risk factor for developing CTIT (odds ratio, 4.26; 95% CI, 1.08-16.78; P = .038). No patients required platelet transfusions or experienced radiation therapy interruptions, and only one patient required a reduction in the dose of chemotherapy throughout the entire study. Moreover, no serious adverse events were reported. rhTPO-related adverse reactions were infrequent and predominantly grade 1 (eg, transient platelet elevation). Prophylactic rhTPO during concurrent chemoradiation therapy for patients with LS-SCLC demonstrated a potential benefit in maintaining platelet counts with a low incidence of CTIT. These findings support further investigation of rhTPO as a preventive strategy for high risk CTIT patients.