CStone, EQRx's anti-PD-L1 antibody sugemalimab hits main goal of lung cancer study

CStone Pharmaceuticals and partner EQRx announced Friday that a Phase III study of sugemalimab as consolidation therapy in patients with locally advanced/unresectable stage III non-small-cell lung cancer (NSCLC), without disease progression after concurrent or sequential chemoradiotherapy, met its primary endpoint of progression-free survival (PFS). The companies noted that the treatment is the first PD(L)1 monoclonal antibody to demonstrate a PFS benefit in this setting.

"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," remarked Frank Jiang, chief executive of CStone. In November last year, CStone reported that sugemalimab plus chemotherapy as a first-line treatment for stage IV squamous or non-squamous NSCLC demonstrated significant and clinically meaningful PFS benefit in the late-stage GEMSTONE-302 trial.

Significant, clinically meaningful improvement in PFS

The latest study, GEMSTONE-301, which is being conducted in China, included 381 patients with locally advanced/unresectable stage III NSCLC without disease progression after concurrent or sequential chemoradiotherapy. Participants were randomised to receive sugemalimab or placebo as consolidation therapy.

Results from the planned interim analysis showed that sugemalimab was associated with a significant and clinically meaningful improvement in PFS as determined by Blinded Independent Central Review (BICR), whilst investigator-assessed PFS was consistent with these results. In subgroup analyses, CStone and EQRx noted that sugemalimab was associated with clinical benefit regardless of whether patients received concurrent or sequential chemoradiotherapy prior to treatment with the anti-PD-L1 antibody.

The drugmakers said that sugemalimab, formerly known as CS1001, was well tolerated in the trial, which is also evaluating overall survival as a secondary goal. Specific study data will be presented at an upcoming medical conference.

Expected to lower cost of immunotherapy

CStone indicated that it plans to seek approval of sugemalimab for stage III NSCLC in China, where it is collaborating with Pfizer on development of the drug. Meanwhile, the Chinese company said it will work with EQRx on regulatory discussions for marketing applications in other countries, including the US (for further analysis, see ViewPoints: EQRx scores a potentially big win for its low-cost drive in lung cancer).

Alexis Borisy, chief executive of EQRx, remarked that while "the PD(L)1 market is becoming more crowded…we see tremendous opportunity for sugemalimab as a monotherapy or in combination regimens, lowering the overall costs of immunotherapy options." The drug is currently being investigated in a number of trials, including a Phase II registration study for lymphoma and Phase III registrational studies in gastric cancer and oesophageal cancer.

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