Updated results from a phase 2 trial of SSGJ-707 (PF-08634404), a PD-1/VEGF bispecific antibody, as monotherapy in patients with advanced non-small cell lung cancer (NSCLC).

Abstract

8514 Background: SSGJ-707 is a fully human IgG4 bispecific antibody that simultaneously binds PD-1 and VEGF. In the phase 2 study (NCT06361927), SSGJ-707 monotherapy demonstrated promising efficacy and manageable safety in first-line NSCLC with PD-L1 tumor proportion score (TPS) ≥1%. We report updated results from this study with the FDA-aligned pivotal dose of 10 mg/kg Q3W. Methods: Patients (pts) with treatment-naive advanced NSCLC (without actionable genomic alterations and PD-L1 TPS ≥1%) were enrolled to receive SSGJ-707 at 5 mg/kg, 10 mg/kg, 20 mg/kg, or 30 mg/kg Q3W until disease progression or unacceptable toxicity. Primary endpoint is objective response rate (ORR) per RECIST 1.1. Secondary endpoints include safety, duration of response (DOR), progression-free survival (PFS), overall survival (OS), and correlation between circulating tumor DNA (ctDNA) and efficacy. Results: As of Nov 28, 2025, 83 pts received ≥1 dose of SSGJ-707, of which 27.7% remained on treatment. In pts treated with the FDA-aligned dose of 10 mg/kg Q3W (n = 34), 41.2% remained on treatment and median duration of follow-up was 15.2 mos (95% CI, 14.3-16.2). In the 10 mg/kg group, confirmed ORR was 67.6% (95% CI, 49.5-82.6%), median DOR was not reached (NR; 95% CI, 10.9-NR), median PFS was 12.4 mos (95% CI, 8.2-NR), and median OS was NR (95% CI, 14.8-NR). High efficacy was noted for the 10 mg/kg Q3W dose irrespective of histology and TPS (table). Among all treated pts (n = 83), treatment-related adverse events (TRAEs) occurred in 92.8%; grade ≥3 TRAEs occurred in 42.2%. The most common grade ≥3 TRAEs (≥5%) were pneumonia (8.4%), hypertension (7.2%), and hemoptysis (6.0%). VEGF-related AEs occurred in 62.7% (grade ≥3, 18.1%) of pts; immune-mediated AEs occurred in 37.3% (grade ≥3, 8.4%). In the 10 mg/kg group, TRAEs led to permanent discontinuation in 1 pt (2.9%) and none had grade 5 TRAE. In pts with detectable ctDNA at baseline (n = 65), median PFS was NR (95% CI, 12.4-NR) in pts with nondetectable ctDNA at C3D1 (n = 19) compared to 7.6 mos (95% CI, 5.6-9.4) in those with detectable ctDNA at C3D1 (n = 33). Conclusions: With longer follow-up, SSGJ-707 monotherapy continues to show promising efficacy with a manageable safety profile in pts with treatment-naive advanced NSCLC across histology and PD-L1 expression subgroups. These results supported initiation of the phase 3 study (Symbiotic-Lung-01) of SSGJ-707 with platinum-based chemotherapy in 1L squamous (SQ) and nonsquamous (NSQ) NSCLC irrespective of TPS (NCT07222566). Clinical trial information: NCT06361927 . n=34 Confirmed ORR, % (95% CI) DOR, mos, median(95% CI) PFS, mos, median (95% CI) OS, mos, median(95% CI) Histology SQ 12 75.0(42.8-94.5) 6.2 (4.1-NR) 8.9 (2.7-NR) NR(4.9-NR) NSQ 22 63.6(40.7-82.8) NR(10.9-NR) 12.4 (8.2-NR) NR(14.8-NR) TPS 1%-49% 21 61.9(38.4-81.9) NR(4.1-NR) 9.6 (7.6-NR) NR(12.1-NR) ≥50% 13 76.9(46.2-95.0) NR(5.6-NR) 12.4(5.9-NR) NR(NR-NR)