CStone's Sugemalimab: A New Standard in Gastric Cancer Treatment

CStone Pharmaceuticals (HKEX: 2616) has announced the publication of the GEMSTONE-303 study results for sugemalimab (Cejemly®) in the prestigious Journal of the American Medical Association (JAMA). The study establishes sugemalimab in combination with chemotherapy as the new standard first-line treatment for patients with PD-L1 combined positive score (CPS) ≥5 gastric or gastroesophageal junction (G/GEJ) adenocarcinoma. This breakthrough has significant implications for the global biopharmaceutical landscape, particularly in the context of other anti-PD-L1 monoclonal antibodies and immunotherapies.



The GEMSTONE-303 study results support sugemalimab in combination with chemotherapy as a new standard first-line treatment for patients with PD-L1 CPS ≥5. The dual primary endpoints of overall survival (OS) and progression-free survival (PFS) demonstrated statistically significant and clinically meaningful improvements compared to placebo plus chemotherapy. Median OS was 15.6 months in the sugemalimab group compared with 12.6 months in the control group, with a hazard ratio (HR) of 0.75 (95% CI, 0.61-0.92), P=0.006. Median PFS was 7.6 months in the sugemalimab group versus 6.1 months in the control group, with a HR of 0.66 (95% CI, 0.54-0.81), P<0.001. Grade ≥3 treatment-related adverse events (TRAE) occurred in 53.9% of patients in the sugemalimab group and 50.6% in the control group, indicating that the safety of this combination regimen was manageable.

Subgroup analyses demonstrated consistent clinical benefits across all pre-defined subgroups, including patients with varying PD-L1 expression levels. In patients with PD-L1 CPS ≥10, sugemalimab plus CAPOX significantly prolonged OS and PFS, with median OS of 17.8 months and median PFS of 7.8 months, respectively. Objective response rate (ORR) was 71.4% in the sugemalimab group compared with 48.6% in the control group.

Dr. Jason Yang, CEO, President of R&D, and Executive Director at CStone, stated: "We are honored to see the GEMSTONE-303 study results published in JAMA. This study establishes sugemalimab in combination with chemotherapy as the new standard first-line treatment for patients with PD-L1 CPS ≥5 G/GEJ adenocarcinoma. To date, sugemalimab has been approved for five indications in China. Internationally, we have expanded its regulatory pathways and forged commercialization partnerships in various global markets. The compelling clinical data from GEMSTONE-303 reinforce our confidence in advancing the global registration and commercialization of sugemalimab. We are committed to unlocking its full clinical potential and providing greater survival benefits to patients worldwide."

Professor Lin Shen, Peking University Cancer Hospital, the leading principal investigator of the GEMSTONE-303 study, said: "Before the availability of PD-1 monoclonal antibodies, chemotherapy was the standard first-line treatment for unresectable, locally advanced or metastatic G/GEJ adenocarcinoma, with median OS rarely exceeding one year. The combination of anti-PD-1 antibodies and chemotherapy has significantly extended survival for these patients. The GEMSTONE-303 study builds on this progress. As the first anti-PD-L1 antibody approved for this patient population, sugemalimab specifically targeted the PD-L1-expressing population in its pivotal study, achieving significant efficacy with a manageable safety profile."

In conclusion, the GEMSTONE-303 study results published in JAMA establish sugemalimab in combination with chemotherapy as the new standard first-line treatment for patients with PD-L1 CPS ≥5 G/GEJ adenocarcinoma. This breakthrough has significant implications for the global biopharmaceutical landscape, particularly in the context of other anti-PD-L1 monoclonal antibodies and immunotherapies. CStone Pharmaceuticals' commitment to advancing the global registration and commercialization of sugemalimab, along with its expanding regulatory pathways and commercialization partnerships, positions the company well for long-term success in the global biopharmaceutical market.