Retrospective analysis of efficacy and safety of romiplostim N01 in the treatment of chemotherapy-induced thrombocytopenia (CIT) in solid tumors

Abstract Background: Chemotherapy-induced thrombocytopenia (CIT), a common hematological toxicity in cancer treatment, occurs when anticancer drugs suppress bone marrow function, particularly megakaryocytes, leading to platelet counts below normal levels. Chemotherapy-induced thrombocytopenia (CIT) may increase bleeding risk, necessitate dose reduction, delay treatment cycles, or lead to therapy discontinuation. These consequences not only compromise anticancer efficacy but also significantly escalate healthcare burdens. Romiplostim N01, a recombinant human thrombopoietin mimetic peptide-Fc fusion protein, is a drug of the TPO-RA class, activates downstream signaling pathways through natural binding sites. It particularly enhances the signal transducer and activator of transcription (STAT) pathway with potent platelet-stimulating effects. The Fc constant region in romiplostim N01 structure extends the drugs half-life, allowing weekly subcutaneous administration. Its absence of endogenous TPO homologous sequences prevents cross-reactivity and neutralizing antibody formation, offering patients with thrombocytopenia a safe, convenient, and effective treatment option. Aims: We conducted a retrospective observational study to evaluate the efficacy and safety of Romiplostim N01 for CIT. Methods: This study enrolled 24 advanced solid tumor patients who received anti-tumor therapy at the Oncology Gastroenterology Department, First Hospital of Shanxi Medical University (July 2024 - July 2025). Eligible participants met the following criteria:Persistent thrombocytopenia (platelet count: 30-75 × 10⁹/L) ≥7 days after chemotherapy completionPatients received subcutaneous romiplostim N01 (3 μg/kg) for platelet recovery assessment. The primary endpoint—hematologic response rate—was defined as the proportion achieving: Platelet count ≥100 × 10⁹/L, or Absolute increase ≥50 × 10⁹/L from baseline without platelet transfusion during the evaluation period. Results: A total of 24 patients were included in the analysis. The median age was 64.5 years (range: 43-79 years), with 19 patients (79.2%) over 60 years old. Twelve patients were female. Tumor types included gastric cancer (7 cases, 29.2%), hepatocellular carcinoma (3 cases, 12.5%), colorectal cancer (9 cases, 37.5%), lung cancer (2 cases, 8.5%), pancreatic cancer (1 case, 4.1%), esophageal cancer (1 case, 4.1%), and ureteral cancer (1 case, 4.1%). One patient had bone metastasis. Regarding anti-tumor treatment regimens, 19 patients (79.2%) received monotherapy chemotherapy, while 5 patients (20.8%) received chemotherapy combined with other treatments. The median baseline platelet count was 63×109/L (range: 19-74 × 109/L). The total effective rate of injection of romiplostim N01 was 83.33% (20/24). Patients achieved platelet count ≥100 × 109 /L or platelet count increased by ≥50 × 109 from baseline, the median time required was 8 days (range: 4-12 days). 15% of patients achieved a platelet count of ≥100 × 10⁹/L or increase of platelet count from baseline of ≥50 × 109/L within 5 days。Conclusion: The results of this study demonstrate that subcutaneous injection of romiplostim N01 is an effective treatment option for CIT, showing high response rates and short recovery time in mixed patient populations.