China-based CStone Pharmaceuticals (HKG: 2616) has announced that its GEMSTONE-303 study for the programmed death-ligand 1 (PD-L1) inhibitor sugemalimab, combined with chemotherapy as a first-line treatment for locally advanced or metastatic gastric/gastroesophageal junction adenocarcinoma (GC/GEJC) with PD-L1 expression ≥ 5%, has reached the primary endpoint of progression-free survival (PFS). This marks a significant milestone in the development of sugemalimab for treating GC/GEJC.
Study Design and Results
The multi-center, randomized, placebo-controlled Phase III regulatory study is designed to assess the efficacy and safety of sugemalimab combined with oxaliplatin and capecitabine for the specified indication. Primary endpoints include investigator-assessed PFS and overall survival (OS), alongside secondary endpoints such as PFS assessed by Blind Independent Central Review (BICR), objective response rate (ORR), and duration of response (DoR) assessed by the investigator. Preliminary results showed that sugemalimab combined with chemotherapy significantly improved PFS compared to the placebo-combined chemotherapy control group (7.6 months vs 6.1 months) and demonstrated a significant benefit trend in OS (14.6 months vs 12.5 months). No new safety signals were identified.
Sugemalimab Profile
Sugemalimab, an in-house developed PD-L1 inhibitor, received its first approval in China in December 2021. Since then, it has gained approvals for use in the first-line treatment of epidermal growth factor receptor (EGFR) gene mutation-negative and anaplastic lymphoma kinase (ALK)-negative metastatic non-squamous non-small cell lung cancer (NSCLC) in combination with pemetrexed and carboplatin; for metastatic squamous NSCLC in combination with pemetrexed and carboplatin; and for unresectable stage III NSCLC without disease progression after platinum-based chemotherapy and radiotherapy. With the positive results in the GEMSTONE-303 study, sugemalimab has become the first PD-L1 inhibitor to achieve positive results in a Phase III study for GC/GEJC globally.-Fineline Info & Tech
