CStone Pharmaceuticals announced that results of the GEMSTONE-302 study, a randomized double-blind registrational clinical study for sugemalimab as the first-line treatment of stage IV non-small cell lung cancer (NSCLC) were published in the world-leading oncology journal The Lancet Oncology. Sugemalimab plus chemotherapy demonstrates statistically significant and clinically meaningful improvement in progression-free survival (PFS) compared with placebo plus chemotherapy. The publication in The Lancet Oncology shows the great academic value and clinical potential of sugemalimab.

Based on the results of the GEMSTONE-302 study, sugemalimab has recently been approved in China in combination with chemotherapy as the first-line treatment of patients with metastatic NSCLC. The GEMSTONE-302 is the world's first randomized, double-blind, phase 3 trial of anti-PD-L1 monoclonal antibody plus chemotherapy as first-line treatment for stage IV squamous or non-squamous NSCLC, and the study was conducted in 35 hospitals and academic research centers in China. The leading Principal Investigator of the GEMSTONE-302 study is Professor Caicun Zhou, Director of the Department of Oncology, Shanghai Pulmonary Hospital.

The GEMSTONE-302 study was designed to evaluate the efficacy and safety of sugemalimab plus chemotherapy compared with placebo plus chemotherapy as first-line treatment of patients with stage IV NSCLC. In 2020, at the pre-planned interim analysis of PFS (median follow-up of 8.6 months), the GEMSTONE-302 study met its primary endpoint with significantly prolonged PFS in the sugemalimab group versus the placebo group. In 2021, with a median follow-up of 17.8 months, the final analysis of PFS showed that sugemalimab plus chemotherapy continued to enhance the benefit in the primary efficacy endpoint of PFS.

The hazard ratio (HR) (95% CI) of investigator-assessed PFS was 0.48 (0.39, 0.60). The median PFS was 9.0 months for sugemalimab plus chemotherapy and 4.9 months for placebo plus chemotherapy. Subgroup analyses of PFS showed clinical benefits across different histological types (squamous or non-squamous) and different PD-L1 expression levels (=1% or <1%).

Sugemalimab plus chemotherapy was well-tolerated, with no new safety signals observed. Meanwhile, sugemalimab showed an encouraging trend for overall survival (OS) in preliminary analysis. The trial is being continued and formal statistical testing for OS is to be performed.

In addition, the National Medical Products Administration (NMPA) of China accepted the new drug application (NDA) for sugemalimab in the treatment of patients with locally advanced (stage III) NSCLC in September 2021, and the review is ongoing. With the positive data of sugemalimab in locally advanced (stage III) and metastatic (stage IV) NSCLC, it has the potential to become the world's first PD-(L)1 monoclonal antibody to cover stage III and stage IV NSCLC in all-comer settings.