Romiplostim N01 Plus ATRA for Persistent Isolated Chemotherapy-Induced Thrombocytopenia After Complete Remission of Gastrointestinal Solid Tumors

Chemotherapy-induced thrombocytopenia is a clinically important complication of anticancer treatment. In some patients, thrombocytopenia persists after completion of chemotherapy despite complete remission of the underlying tumor. Persistent isolated chemotherapy-induced thrombocytopenia (PICIT) is characterized by prolonged thrombocytopenia with relatively preserved red blood cell and neutrophil counts, after exclusion of other causes of thrombocytopenia. This study focuses on adult patients with PICIT after complete remission of gastrointestinal/digestive system solid tumors, including but not limited to gastrointestinal tract, pancreatic, and colorectal cancers. Romiplostim N01 is a thrombopoietin receptor agonist intended to stimulate megakaryocyte proliferation and platelet production. All-trans retinoic acid (ATRA) may provide additional hematopoietic and immunomodulatory effects. The study will compare Romiplostim N01 plus ATRA with Romiplostim N01 alone. Eligible participants will be centrally randomized in a 1:1 ratio to one of two treatment arms. Participants in the experimental arm will receive Romiplostim N01 by subcutaneous injection once weekly plus oral ATRA twice daily for 12 weeks. Participants in the active comparator arm will receive Romiplostim N01 alone once weekly for 12 weeks. Romiplostim N01 dose adjustment will be based on platelet count according to the protocol. Supportive care and rescue treatment, including platelet transfusion for severe bleeding or clinically indicated thrombocytopenia, are permitted. Participants will be followed weekly during Weeks 1 to 12 and every 2 weeks during Weeks 13 to 24. The primary endpoint is overall response rate at Week 12. Secondary endpoints include sustained response rate during Weeks 13 to 24, complete response rate, partial response rate, duration of response, time to response, platelet count changes, platelet transfusion requirements, bleeding events, and adverse events. Safety will be assessed by monitoring adverse events and serious adverse events, including ATRA-related toxicities and thrombopoietin receptor agonist-associated risks such as thromboembolic events.