CStone Pharmaceuticals and partner EQRx announced top-line results Tuesday showing that the investigational anti-PD-L1 antibody sugemalimab, plus chemotherapy, significantly prolonged overall survival (OS) compared to chemotherapy alone in first-line non-small-cell lung cancer (NSCLC). The result satisfied a key secondary endpoint of the Phase III GEMSTONE-302 trial, which had previously met its main goal of progression-free survival (PFS).

The trial, which was conducted in China by CStone, included 479 patients with stage IV squamous or non-squamous NSCLC. Subjects were randomly assigned sugemalimab or placebo, both together with carboplatin-based chemotherapy as a first-line treatment.

Aside from meeting the OS endpoint, the companies noted that clinical benefit was observed across subgroups, including patients with squamous and non-squamous subtypes, and regardless of PD-L1 expression levels. They added that sugemalimab had a safety profile in line with the PD-1/PD-L1 class. Detailed GEMSTONE-302 results will be submitted for presentation at a future medical congress.

Recent approval in China

"Price remains a barrier to accessing innovative therapies for many people with lung cancer around the world, despite the availability of multiple anti-PD-(L)1 therapies," remarked Vince Miller, physician-in-chief at EQRx, which launched in 2020 with the express purpose of developing medicines at radically lower prices. "We look forward to engaging with global regulatory authorities with the aim of delivering a lower-cost treatment option to patients upon approval," Miller added. Sugemalimab was recently approved in China, under the name Cejemly, in combination with chemotherapy for treatment-naïve stave IV NSCLC. For related analysis, see ViewPoints: Could China's PD-1 inhibitors shake up the US checkpoint market in 2022? 

CStone and EQRx are also investigating sugemalimab as a consolidation therapy in patients with locally advanced, unresectable stage III NSCLC without disease progression after either concurrent or sequential chemoradiotherapy in the Phase III GEMSTONE-301 trial. That study has also met its primary goal, extending PFS by a median 9 months, compared to 5.8 months for placebo, according to results presented last September at the European Society for Medical Oncology (ESMO) congress.