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

This first-in-human study consists of a dose-escalation part (Part Ia) and a dose-expansion part (Part Ib). In Part Ia, adults with selected locally advanced or metastatic solid tumors will receive FXB0871 monotherapy by intravenous infusion every 2 weeks in sequential pre-determinde dose cohorts using a Bayesian optimal interval design. The planned dosing schedule is every 2 weeks, with a dose-limiting toxicity observation period of the first 2 treatment cycles. Additional intermediate dose levels, cohort expansion, and schedule optimization to every 3 or 4 weeks may be allowed according to protocol-defined safety, PK/PD, and preliminary antitumor activity data. Part Ib will start after determination of the monotherapy recommended phase 2 dose (RP2D). Cohort A will enroll participants with PD-(L)1-resistant locally advanced or metastatic non-small cell lung cancer and randomize them 1:1 to receive FXB0871 at the RP2D or at a lower dose selected on the basis of Part Ia data. Cohort B will enroll participants with PD-(L)1-resistant locally advanced or metastatic hepatocellular carcinoma to receive FXB0871 at the RP2D. Participants may continue study treatment for up to 12 months or until unacceptable toxicity, disease progression, or another protocol-defined discontinuation criterion is met.