Phase 3 Trial of Sugemalimab in Stage III NSCLC Meets Primary End Point


Based on positive phase 3 results, a new drug application for sugemalimab to treat patients with locally advanced or unresectable stage III non–small cell lung cancer will likely be submitted to the FDA.

The phase 3 GEMSTONE-301 trial (NCT03728556) of the anti–PD-L1 monoclonal antibody sugemalimab met its primary end point of progression-free survival (PFS) improvement versus placebo in patients with locally advanced or unresectable stage III non–small cell lung cancer (NSCLC) not progressing following concurrent or sequential chemoradiation, announced the company responsible for the agent, CStone Pharmaceuticals.

The findings from the planned interim analysis reviewed by the independent Data Monitoring Committee showed a statistically significant and clinically meaningful PFS benefit by both blinded independent central review and investigator assessment. Subgroup analyses revealed a consistent benefit of sugemalimab in patients regardless of prior therapy.

“Currently, there has not been an approved PD-1 or PD-L1 monoclonal antibody for treating patients in stage III NSCLC who have not developed disease progression after sequential chemoradiotherapy,” Jason Yang, Chief Medical Officer of CStone, said in a press release. “The GEMSTONE-301 is the first-in-class clinical study design that enrolled patients with either concurrent or sequential chemoradiotherapy to better reflect real-world clinical practice and cover a broader population. CStone is committed to providing treatment options to address the unmet medical needs. The GEMSTONE-301 study will advance the use of multidisciplinary treatment approaches in China to improve the quality of the diagnosis and treatment of stage III NSCLC. We will continue to explore the potential of sugemalimab in registrational clinical trials for patients with hematologic malignancies and advanced gastric and esophageal cancers.”

In addition to a new drug application planned for submission to the National Medical Products Administration of China for the treatment of the indicated patient population, the company is planning regulatory discussions regarding NDAs for sugemalimab in stage III and IV NSCLC with the FDA.

The ongoing randomized, double-blind, placebo-controlled trial has a recruitment goal of 381 patients who have histologically confirmed locally advanced/unresectable stage III NSCLC. Patients are to receive either intravenous sugemalimab at 1200 mg every 3 weeks for up to 24 months or matched placebo.

Patients should receive their first dose of therapy 1 to 42 days after concurrent or sequential chemoradiotherapy is completed. To be eligible, patients must have received platinum-containing chemotherapy, no progression after treatment, an ECOG performance status of 0 or 1, and life expectancy of 12 weeks or more. Patients who have mixed histology with a small cell lung cancer component, disease progression, major surgical procedures within 28 days, prior experience with immune checkpoint inhibitors, or autoimmune disease are not eligible for enrollment.

To commercialize the agent in China and global markets, CStone formed collaborative agreements with Pfizer and EQRx. “We are excited that sugemalimab becomes the first anti–PD-1/PD-L1 monoclonal antibody in the world to cover both stage III and stage IV NSCLC patients,” Frank Jiang, Chairman and CEO of CStone, said in a press release. “The continued success of sugemalimab in lung cancer demonstrates CStone’s leading research and development capabilities in the field of immuno-oncology. We are working closely with Pfizer and EQRx, our commercial partners for sugemalimab, on the next steps in our joint efforts to deliver this best-in-class drug to patients worldwide.”

In addition to this trial, sugemalimab is being explored in several phase 1 and 2 trials for indications in lymphoma and gastric and esophageal cancers. The pivotal single-arm, multicenter phase 2 CS1001-201 trial is evaluating the safety and efficacy of the agent in adult patients with relapsed or refractory extranodal natural killer/T-cell lymphoma (R/R ENKTL). Previously, the FDA granted orphan drug designation to sugemalimab for the treatment of T-cell lymphoma and breakthrough therapy designation for R/R ENKTL.


CStone Announces the First-in-Class Registrational Clinical Trial of Sugemalimab Met its Primary Endpoint in Stage III NSCLC and Plans to Submit a New Drug Application. News release. CStone. May 27, 2021. Accessed June 2, 2021.

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