GSK’s lung cancer drug shows 94% response rate in frontline trial

GSK ↘ 0.08% presented data on Monday at the 2026 World Conference on Lung Cancer in Seoul showing that its ROS1 inhibitor Jideytro, known generically as zidesamtinib, produced a 94% objective response rate in patients with advanced ROS1-positive non-small cell lung cancer who had not previously been treated with a tyrosine kinase inhibitor. The results, from the phase 1/2 ARROS-1 trial, prompted the company to announce plans for a supplemental FDA application to expand the drug into first-line use later this year.

Among 94 evaluable patients, 88 responded to treatment, including 14 who achieved a complete response, according to GSK's press release. After a median follow-up of 15.2 months, 90% of patients remained progression-free at 12 months. The drug also showed notable activity against brain metastases: all 10 evaluable patients with central nervous system involvement responded, and 70% achieved complete intracranial clearance.gsk+3

A New Standard in a Rare Cancer Subset

ROS1-positive NSCLC accounts for roughly 1-2% of all lung cancer cases, making it a rare but well-defined molecular subgroup. Existing frontline options such as crizotinib and entrectinib have shown response rates in the range of 68-79%, making zidesamtinib's 94% figure a notable advance if confirmed in further study.pmc.ncbi.nlm.nih

"Zidesamtinib demonstrated clinically meaningful activity in TKI-naive patients with ROS1-positive NSCLC, with a safety profile consistent with previous reports and low rates of dose reduction and discontinuation," said Alexander Drilon of Memorial Sloan Kettering Cancer Center, who presented the findings. Treatment-related adverse events led to dose reductions in 11% of patients and discontinuation in just 1%.medicalxpress

Path to Broader Approval

The FDA approved zidesamtinib on July 22, 2026, for adults with ROS1-positive NSCLC who had received at least one prior ROS1 TKI. That approval, which came ahead of the original September 18 target action date, was based on a 44% response rate in 117 previously treated patients. The drug carries orphan drug and breakthrough therapy designations.gsk+1

GSK said it plans to file a supplemental New Drug Application with the FDA later in 2026 to seek first-line approval. The ARROS-1 trial enrolled a geographically diverse population, with roughly equal shares of patients from the Asia-Pacific region, Europe, and North America. Patients in the frontline cohort were permitted to have received up to one prior line of chemotherapy, with or without immunotherapy.fiercepharma+2