2589 Background: HB0025 is a recombinant humanized anti-PD-L1 monoclonal antibody-VEGFR1 fusion Protein. Nonclinical data both in vitro and vivo have shown high-affinity binding to both targets as well as the inhibition of tumor growth in animal models. Here, we present preliminary safety and efficacy data from a dose escalation phase I study of HB0025. Methods: Eligible patients(pts) were ≥18 years old (ECOG PS 0–1) who had advanced solid tumors (NSCLC, gynecological tumors, digestive system tumors, etc.) and failed standard treatment. This phase 1 dose escalation includes accelerated titration (0.01, 0.03, 0.1 and 0.3mg/kg) and conventional 3+3 dose escalation (1.0, 3.0, 6.0, 10, 12, 20, and 30.0 mg/kg). HB0025 is administered intravenously every 14 days (Q2W). Objectives include evaluation of safety, pharmacokinetics (PK), pharmacodynamics (PD), immunogenicity, and antitumor activity. Adverse events (AEs) were reported with CTCAE v5.0 and DLTs were evaluated within a 28-day window. Results: As of Aug 30th 2022, 30 pts including 8 male and 22 female from Caucasian and Mongoloid have received HB0025 at doses of 0.01 mg/kg (n=1), 0.03 mg/kg (n=2), 0.1 mg/kg (n=1), 0.3 mg/kg (n=1),1.0 mg/kg (n=3), 3.0 mg/kg (n=7), 6.0mg/kg (n=7), 10.0 mg/kg (n=5), and 12.0mg/kg (n=3) Q2W. Overall, the median age was 55 years and the median lines of previous treatment was four. Of the 22 evaluable pts dosed at ≥ 3 mg/kg Q2W, the ORR was 9.1% (2/22) and the disease control rate (DCR) was 50% [11/22]. Among the 2 responders, a CR (colorectal ca) pt whose prior therapy was no immune checkpoint inhibitor (ICI) or bevacizumab have continued more than 36 weeks; and a PR (NSCLC) pt with duration more than 18 weeks whose tumor was 60.2% regression and prior ICI failure. Till the date of submission, the therapy was continuing for the CR and PR pts. Treatment-related adverse events (TRAEs) occurred in 83.3% of pts. The grade 3 TRAEs occurred in 20% [6/30] and treatment-related SAEs occurred in 13.3% [4/30]. One DLT occurred in the 12.0mg/kg cohort. No death occurred related to HB0025. TRAEs leading to treatment discontinuation occurred in 13.3% of pts [4/30]. The most frequent TRAEs were hypertriglyceridemia (23.3%), hypercholesterolemia (23.3%), anemia (16.7%), alanine aminotransferase increase (16.7%), and proteinuria (13.3%). Conclusions: HB0025 shows manageable safety and promising anti-tumor activity in pts with various solid tumors. To better characterize the risk-benefit profile, HB0025 is currently enrolled at 20.0 mg/kg Q2W and is being explored at doses 10 mg/kg in expansion cohorts. The future data, including PK, PD and ADA will be presented. Clinical trial information: NCT04678908 .