Envafolimab in combination with lenvatinib and albumin paclitaxel for previously treated advanced GEJ adenocarcinoma: Latest analysis of a phase II, two-cohort study.

375 Background: The combination of first-line chemotherapy and PD-1 has emerged as a standard treatment, enhancing the efficacy in advanced gastric/gastroesophageal junction (GEJ) cancer. The efficacy of the combination of second-line chemotherapy and PD-1/PD-L1 remains unclear. This study aims to observe the efficacy of Envafolimab (PD-L1 inhibitor ) plus tyrosine kinase inhibitors (TKIs) and second-line chemotherapy in the treatment of patients (pts) with advanced GEJ adenocarcinoma. Methods: Eligible pts with HER2-negative, microsatellite stable (MSS), advanced GEJ adenocarcinoma were enrolled in this study. Pts who never received PD-1 or PD-L1 inhibitors before would assign into Group A. Pts in Group B have failed first-line PD-1 antibody combined chemotherapy, with optimal efficacy as or above stable disease (SD). Pts in both groups received Envafolimab (200mg, hypodermic injection, days 1, 15, Q4W) combined with Lenvatinib (8mg/12mg, po, once a day) and albumin paclitaxel (100mg/m2, IV, days 1, 8 and 15, Q4W, up to 6 cycles) until disease progression, unacceptable toxicity, or pts refusal to continue treatment. The primary endpoint was objective response rate(ORR) per iRECISTv1.1, and the secondary endpoints included disease control rate (DCR), progression free survival (PFS), overall survival (OS) and safety. Results: From Oct 2022 to Apr 2024, 32 pts were enrolled. Both groups enrolled 16 pts equally, and 15 pts of each group were evaluable for efficacy analysis. The average ages were 60.07 ± 11.73 y and 50.13 ± 12.18 y in group A and B respectively. In group A, 7 pts had been tested for PD-L1 status, of which 2 (13.3%) was positive and 5 (33.3%) were negative. PD-L1 status was negative in 5(33.3%) pts, positive in 9 (60.0%), and untested in 1(6.7%) in group B. As of Sep 14, 2024, The ORR was 60.0% (9/15) in group A and 46.7% (7/15) in group B. The DCR was 100.0% (15/15) in both groups. After a median follow-up of 17.0 mo (IQR: 8.0-18.8) in group A, the mPFS was 8.2 mo (95% CI = 6.1-10.4), and the mOS was 14.8 mo(95% CI = 7.4-22.2). With median follow-up of 9.0 mo (IQR: 6.1-16.2) in group B, the mPFS was 5.9 mo (95% CI= 3.8-8.1) and the mOS was 11.5 mo (95% CI = 3.1-19.9). Overall incidences of adverse events (AEs) of any grade was 100% (30/30), and 80.0% (24/30) pts had ≥ grade 3 AEs during treatment. Most treatment-related adverse events (TRAEs) of grade ≥3 included decreased neutrophil count (73.3%), decreased leukocyte count (63.33%), Anemia (10%), febrile neutropenia (6.67%). Conclusions: In pts of advanced gastric cancer who have previously received PD-1 inhibitors or not, this second-line combination therapy demonstrates promising preliminary effects. Pts who have not previously received ICIs might benefit more from this combination therapy. Clinical trial information: NCT06030934 .