A Single-Arm, Open-Label Phase Ia/Ib Clinical Trial Evaluating the Safety, Tolerability, Pharmacokinetic Profile, and Preliminary Efficacy of FS-207 in Patients With Advanced Solid Tumors With High Microsatellite Instability (MSI-H)

Who cannot join

• 1) Known diagnosis of Werner syndrome; 2) Prior treatment with any medication targeting Werner syndrome helicase (WRN); 3) Receipt of any anti-tumor therapy within 3 weeks or 5 half-lives (whichever is longer) prior to the first dose; 4) Patients with adverse events related to prior anti-tumor therapy that have not resolved to Grade ≤1 (according to NCI CTCAE v6.0), excluding toxicities deemed by the investigator to pose no safety risk-such as alopecia, Grade 2 peripheral neuropathy, hypothyroidism stable on hormone replacement therapy, mild rash, hyperpigmentation, etc.-with specific cases subject to the investigator's judgment; 5) Undergone, or scheduled to undergo during the study period, major surgery (excluding procedures for vascular access placement, or biopsies performed via laparoscopy, mediastinoscopy, or thoracoscopy) within 4 weeks prior to the first dose; or undergone radical radiotherapy (palliative radiotherapy within 2 weeks prior to the first dose); 6) Leptomeningeal metastases; central nervous system (CNS) metastases with clinical symptoms; or other evidence indicating that CNS metastases are not adequately controlled, as determined by the investigator to render the participant unsuitable for enrollment. 7) Patients with symptomatic and unstable pleural effusion, ascites, or pericardial effusion, as determined by the investigator (patients whose clinical symptoms stabilize following therapeutic drainage of pleural fluid, ascites, or pericardial fluid may be enrolled); 8) Patients with other severe or uncontrolled systemic diseases, as determined by the investigator, including but not limited to interstitial lung disease, non-infectious pneumonitis; uncontrolled diabetes, renal disease requiring dialysis, severe hepatic disease (Child-Pugh Class B or C), acute pancreatitis, etc.; 9) Patients with cardiovascular diseases of significant clinical relevance;
• 10) Patients with dysphagia, or gastrointestinal dysfunction or disease that could significantly affect the absorption of FS-207 tablets (e.g., severe ulcerative disease, poorly controlled nausea, vomiting, diarrhea, malabsorption syndrome, small bowel resection, etc.); 11) Patients with active autoimmune disease requiring systemic treatment, or a history of autoimmune disease with a potential for recurrence; 12) Patients with active Hepatitis B; active Hepatitis C; or Human Immunodeficiency Virus (HIV) infection; 13) Patients who have received a live vaccine or attenuated live vaccine within 4 weeks prior to the first dose of study medication; administration of inactivated vaccines is permitted; 14) Patients who have received treatment with other investigational drugs not yet approved for marketing, or who have participated in clinical trials involving interventional medical devices, within 4 weeks prior to the first dose of study medication; 15) Patients with active pulmonary tuberculosis (TB) (patients suspected of having active TB must undergo further evaluation by an infectious disease specialist to establish a definitive diagnosis) or a history of active TB; 16) Patients with any active infection requiring systemic treatment occurring within 2 weeks prior to the first dose of study medication; 17) Participants with a known or suspected history of severe allergic reactions to any component of the investigational drug, or a history of uncontrolled allergic asthma; 18) Patients who have previously undergone organ transplantation or allogeneic hematopoietic stem cell transplantation; 19) History of substance abuse, or known medical, psychological, or social conditions-such as a history of alcoholism or drug abuse; 20) Women who are pregnant or breastfeeding, or women of childbearing potential who have a positive pregnancy test result during the screening period; 21) Any other conditions that the investigator deems render the participant unsuitable for participation in this trial.