IMM2510, an anti-PD-L1/VEGF bispecific antibody fusion protein, in patients with R/R STS: A phase Ib expansion study.

Abstract

11545 Background: IMM2510 is a novel bispecific antibody fusion protein targeting PD-L1 and VEGF. The results of dose-escalation phase were previously reported. Here, we report further efficacy and safety of soft tissue sarcoma patients in cohort expansion stage. Methods: IMM2510-01 was a phase I, multicenter, open-label study designed to evaluate the safety, efficacy, recommended phase II dose (RP2D), and pharmacokinetics (PK) of IMM2510 monotherapy (NCT05972460). Dose escalation stage completed and administration of IMM2510 at 20mg/kg, Q2W was selected for cohort expansion. Advanced soft tissue sarcoma patients after prior systemic treatment failure were enrolled, including these with alveolar soft part sarcoma (ASPS), undifferentiated pleomorphic sarcoma (UPS), leiomyosarcoma (LMS) and synovial sarcoma (SS) patients. The primary endpoint was safety, tolerability and investigator assessed ORR. Results: As of 24 Dec 2024, 29 STS patients were treated in cohort expansion stage, including 10 with ASPS, 5 with UPS, 8 with LMS, 5 with SS and 1 with other STS subtypes. The median age was 45 and most patients (89.7%) were ECOG PS 1. The median number of prior systemic treatment was 2. Most patients (96.6%) experienced treatment-related adverse events (TRAEs), of which 3 (10.3%) were ≥ Grade 3. The most common TRAEs of any grade was infusion-related reaction (IRR) (37.9%), platelet decreased (31%) and AST increased (27.6%). TRAE of ≥ Grade 3 was reported in 3 patients, including 1 platelet decreased, 1 transaminase increased and 1 hypoaesthesia. No TRAE leading to treatment discontinuation was observed. Of 27 efficacy-evaluable STS patients, ORR was 7.4% and DCR was 55.6%. 2 PR and 4 SD with tumor shrinkage were observed. PRs were noted in the UPS and LMS cohorts, with an ORR of 20% and 14.3%, and a DCR of 60% and 42.9%, respectively. The DOR was not reached in UPS and 3.68 months in LMS. The study is ongoing. Conclusions: IMM2510 monotherapy demonstrated active anti-tumor activity in R/R STS patients with tolerable toxicity. Clinical trial information: NCT05972460 .