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

Prior treatment

• 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.
• Systemic corticosteroids (≥10 mg/day prednisone equivalent) or other immunosuppressive therapy within 28 days before first dose, with limited protocol-defined exceptions.
• Uncontrolled infection or clinically significant unresolved toxicities from prior therapy.

Other illness

• Active autoimmune disease requiring systemic treatment or immunodeficiency.
• Active or untreated central nervous system metastases, carcinomatous meningitis, or leptomeningeal disease.
• Clinically significant cardiovascular/cerebrovascular disease, uncontrolled effusions/ascites, uncontrolled hypertension, or QTcF \>470 ms.
• Active hepatitis B/C, syphilis, or HIV infection.
• Clinically significant interstitial lung disease or active noninfectious pneumonitis.
• Any other serious medical or psychiatric condition that, in the investigator's judgment, would make participation inappropriate.

Other

• Pregnancy or breastfeeding.

• 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.