Phase Ia/Ib Study of FXB0871 Monotherapy in Locally Advanced/Metastatic Solid Tumors

Inclusion Criteria: * Signed informed consent. * Age ≥18 years. * Histologically confirmed selected locally advanced or metastatic solid tumor with progression on, intolerance to, or no suitable standard therapy. * ECOG performance status 0 or 1. * At least one measurable lesion per RECIST v1.1. * Pretreatment tumor tissue available (archival or fresh biopsy). * Life expectancy ≥12 weeks. * Oxygen saturation ≥92% on room air. * Left ventricular ejection fraction \>50%. * Adequate hematologic, coagulation, renal, hepatic, and cardiac function. * Women of childbearing potential and sexually active men must use highly effective contraception. * Tumor-specific eligibility applies, including prior anti-PD-(L)1 treatment failure for the selected cohorts. Key Exclusion Criteria: * Systemic anti-cancer therapy, major surgery, or radical radiotherapy within 4 weeks before first dose. * Prior treatment with IL-2, IL-15, or IL-7. * Active autoimmune disease requiring systemic treatment or immunodeficiency. * Systemic corticosteroids (≥10 mg/day prednisone equivalent) or other immunosuppressive therapy within 28 days before first dose, with limited protocol-defined exceptions. * Active or untreated central nervous system metastases, carcinomatous meningitis, or leptomeningeal disease. * Uncontrolled infection or clinically significant unresolved toxicities from prior therapy. * Clinically significant cardiovascular/cerebrovascular disease, uncontrolled effusions/ascites, uncontrolled …