A phase III randomized, double-blinded, placebo-controlled study of suvemcitug combined with chemotherapy for platinum-resistant ovarian cancer (SCORES).

LBA5516 Background: Suvemcitug is a new-generation recombinant humanized anti-VEGF rabbit monoclonal antibody. In the previous P1b study, Suvemcitug demonstrated its favorable safety profile and efficacy signals when combo with chemotherapy in platinum-resistant ovarian cancer (PROC). SCORES is the first randomized, double-blind, placebo-controlled phase III clinical trial to confirm the efficacy of Suvemcitug combo with chemo in PROC, whether or not previously received antiangiogenic agents or PARP inhibitors. Methods: Eligible patients had progressed during platinum-based therapy or within 6 months after ≥4 cycles of platinum-based therapy with at least one measurable lesion. After the investigators chose chemotherapy (CT) (weekly paclitaxel 80 mg/ m 2 d1, 8, 15 & 22 q4w, pegylated liposomal doxorubicin 40 mg/m 2 d1 q4w or topotecan 4 mg/m 2 d1, 8 & 15 q4w), patients were randomly assigned (2:1) to either Suvemcitug (1.5 mg/kg q2w) or placebo combine with CT until progression or unacceptable toxicity. The primary endpoint was progression-free survival (PFS) by blinded independent review committee (BIRC) according to the RECIST 1.1. Key secondary end point is the overall survival (OS). Results: A total of 421 patients were enrolled between June 2021 and June 2023 in China. As the data cut off of the primary efficacy analysis (8 December 2023), 197 PFS events (70.1%) in Suvemcitug arm and 111 PFS events (79.3%) in placebo arm had occurred with the median follow-up of 14.36 and 14.26 months, respectively. The median PFS by BIRC was 5.49 months in Suvemcitug arm versus 2.73 months in placebo arm (hazard ratio[HR] 0.46, p<0.0001). OS data are immature. 42.7% and 50.7% of patients are deceased in Suvemcitug arm or placebo arm respectively, and there is a trend of OS benefit trend: median OS 16.07 months vs. 14.88 months, HR 0.79, p=0.1244. Efficacy results are summarized below. Treatment-emergent adverse events (TRAEs) occurred in all patients in Suvemcitug arm, with the most common being neutrophil count decreased, white blood cell count decreased and platelet count decreased. No Suvemcitug-related grade 5 TEAE occurred. Conclusions: To the best of our knowledge, this is the first double-blinded phase III study demonstrated promising antitumor activity of anti-angiogenic agent in patients with PROC. The improvement in PFS, ORR and DCR gained by adding Suvemcitug to single-agent CT was observed with no new safety concern. Clinical trial information: NCT04908787 . [Table: see text]