CStone Pharmaceuticals has reported that its sugemalimab met the primary goal of improving progression-free survival (PFS) in a Phase III GEMSTONE-301 clinical study conducted on patients with stage III non-small-cell lung cancer (NSCLC).

Sugemalimab is an investigational anti-programmed cell death ligand 1 (PD-L1) monoclonal antibody. It mimics the natural G-type immunoglobulin 4 human antibody, which lowers immunogenicity and possible toxicity risks.

The multi-centre, randomised, double-blind Phase III GEMSTONE-301 trial assessed the efficacy and safety of sugemalimab as consolidation therapy in locally advanced/unresectable stage III NSCLC subjects who had no disease progression on receiving concurrent or sequential chemoradiotherapy.

The secondary goals of the trial included safety profile, overall survival, and PFS as evaluated by investigators.

The latest interim analysis data demonstrated that subjects receiving sugemalimab had a statistically significant and clinically meaningful increase in PFS.

In addition, the investigator evaluated PFS was in line with the primary endpoint data.

The antibody was found to be well-tolerated in the trial, with no new safety signals noted.

Sugemalimab offered clinical benefit irrespective of whether patients received concurrent or sequential chemoradiotherapy before the antibody treatment, subgroup analyses showed.

CStone Pharmaceuticals chairman and CEO Dr Frank Jiang said: “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.

“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.”

The company intends to submit a new drug application (NDA) to the Chinese drug regulator National Medical Products Administration for sugemalimab in stage III NSCLC indication.

CStone along with EQRx will have discussions on stage III and stage IV NSCLC indications with various regulators, which includes the US Food and Drug Administration.

In October last year, CStone completed the previously announced share subscription agreement through which a Pfizer affiliate subscribed for newly issued CStone shares at around $200m.