On September 13, 2026 GSK plc (LSE/NYSE: GSK) reported positive results from the registrational phase I/II ARROS-1 trial evaluating Jideytro (zidesamtinib) in patients with advanced or metastatic ROS1-positive non-small cell lung cancer (NSCLC) who had not received previous treatment with a tyrosine kinase inhibitor (TKI-naïve). The data were presented in a Presidential Symposium session at the 2026 World Conference on Lung Cancer (WCLC) in Seoul, South Korea, and will support a planned supplemental New Drug Application to the US FDA this year to expand the indication for Jideytro to include first-line treatment.
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In the 94 TKI-naïve patients included in the analysis, zidesamtinib achieved a clinically meaningful 94% objective response rate (ORR) (88/94; 95% CI: 87-98), including a 15% complete response rate (14/94), after a median follow-up of 15.2 months (range 1.1–30.5). Responses were durable, with 94% of patients continuing to respond to treatment at nine months and 86% at 12 months. Progression-free survival (PFS) was 90% at 12 months. Median duration of response (DOR) and median PFS had not been reached at the time of analysis. In the trial, 100% of patients with measurable brain metastases at baseline (n=10) responded to zidesamtinib (10/10, 95% CI: 69–100), and 70% achieved a complete clearance of detectable brain tumours (7/10). At 12 months, 78% of patients maintained an intracranial response, and no central nervous system progression events were observed among patients without brain metastases at baseline.1
Hesham Abdullah, Senior Vice President, Global Head of Oncology, R&D, GSK said, "Today’s results show a combination of high response rates and a tolerability profile that helped most patients stay on treatment. They highlight the potential for a differentiated profile for zidesamtinib to become a first-line treatment for patients with ROS1-positive NSCLC – a condition where maintaining long-term disease control, managing spread to the brain and minimising treatment-related side effects remain key challenges. We look forward to sharing these data with regulators."
Low rates of treatment discontinuation were observed, consistent with previous safety reports for zidesamtinib. The most common (≥15%) treatment-related adverse events (TRAEs) were peripheral oedema, weight increase, blood creatine phosphokinase increase, dysgeusia and aspartate aminotransferase increase; most were low grade. TRAEs led to dose reductions in 11% of patients and discontinuation in 1%.1
Alexander Drilon, MD, ARROS-1 primary investigator and Chief of the Early Drug Development Service at Memorial Sloan Kettering Cancer Center, said: "Patients with ROS1-positive NSCLC may receive treatment for many years while continuing to work, care for their families and live their daily lives. They need treatments that provide lasting control of their disease, including in the brain, while limiting side effects and treatment disruption. The durable responses and low rates of treatment discontinuation observed in ARROS-1 represent encouraging progress toward addressing these long-term treatment needs."
Zidesamtinib is not approved anywhere in the world for use as first-line therapy. In July 2026, the FDA approved zidesamtinib for patients with ROS1-positive NSCLC previously treated with a TKI.2
About ARROS-1
The global, single-arm, first-in-human phase I/II ARROS-1 study (NCT05118789) included a phase II cohort of patients with locally advanced or metastatic ROS1-positive NSCLC who were naïve to ROS1 tyrosine kinase inhibitor (TKI) therapy, with up to one prior line of chemotherapy and/or immunotherapy permitted. Of 532 patients with ROS1-positive NSCLC who received zidesamtinib 100 mg once daily across all lines of therapy, 183 were receiving their first TKI-targeted treatment. The efficacy-evaluable population (n=94) included patients with measurable disease (by blinded independent central review) who initiated treatment by 15 June 2025, to allow at least nine months of follow-up for duration of response. 27% had received prior chemotherapy, 17% of whom also had prior immunotherapy. 17% had baseline central nervous system metastases by BICR. Data cut-off was 16 April 2026.
About ROS1-positive NSCLC
ROS1 mutations occur in approximately 2% of non-small cell lung cancers, contributing to an estimated 50,000 new diagnoses worldwide each year, typically in younger patients and more often in non-smokers. The disease has a high propensity to spread to the central nervous system, with brain metastases present in up to 40% of patients at diagnosis and remaining a common site of disease progression during treatment. Despite advances in targeted therapies, unmet need remains due to challenges including central nervous system progression, acquired resistance and treatment tolerability.3-6
About Jideytro
Jideytro (zidesamtinib), part of GSK’s portfolio from the recently completed acquisition of Nuvalent, Inc.7, was designed as a ROS1 TKI with broad coverage of ROS1 resistance mutations, activity against disease that has spread to the brain, durable treatment responses and a tolerable profile. Together, these features aim to help patients maintain disease control for longer while reducing the treatment challenges that can emerge over time.
Jideytro is FDA approved for the treatment of adult patients with locally advanced or metastatic ROS1-positive non-small cell lung cancer (NSCLC) who received a prior ROS1 TKI.
(Press release, GlaxoSmithKline, SEP 13, 2026, View Source [SID1234670817])