Jideytro Shrank Tumors in 94% of Patients With ROS1-Positive Lung Cancer

Jideytro (zidesamtinib) shrank tumors in 94% of patients with advanced or metastatic ROS1-positive non-small cell lung cancer (NSCLC) who had not previously received a ROS1 tyrosine kinase inhibitor (TKI), according to findings from the phase 1/2 ARROS-1 trial.

ROS1-positive lung cancer is driven by a change in the ROS1 gene. TKIs are targeted therapies designed to block proteins that help these cancer cells grow.

How well did Jideytro work in the ARROS-1 trial?

Among 94 patients, 88 (94%) experienced an objective response, meaning their tumors shrank by a predetermined amount on scans. The objective response rate was the main goal of the phase 2 portion of the trial and was assessed by independent radiologists. Fourteen patients (15%) had a complete response, meaning no signs of cancer were detected on scans.

Responses also appeared to last over time. The median duration of response had not yet been reached, meaning more than half of patients who responded were still responding when the data were analyzed. At 12 months, an estimated 86% of responses were ongoing.

The median progression-free survival, or the length of time patients lived without their cancer growing or spreading, had also not been reached. At 12 months, 90% of patients were living without disease progression. Patients had been followed for a median of 15.2 months.

“[Jideytro] demonstrated clinically meaningful activity in [patients new to TKIs] with advanced ROS1-positive [non-small cell lung cancer],” lead study author Dr. Alexander Drilon, chief of the Early Drug Development Service at Memorial Sloan Kettering Cancer Center in New York, said during the presentation.

Did Jideytro work against lung cancer that spread to the brain?

Ten patients entered the trial with measurable cancer that had spread to the brain and had not received brain radiation within the previous two months. All 10 patients (100%) experienced shrinkage of their brain tumors, including seven (70%) who had a complete response in the brain.

At 12 months, 78% of the brain responses were still ongoing.

Among 78 patients who did not have cancer in the brain when they entered the trial, none developed new cancer in the brain during the study period.

Who was included in the ARROS-1 trial?

ARROS-1 is a global trial evaluating Jideytro in patients with advanced ROS1-positive NSCLC and other ROS1-positive solid tumors.

Patients included in this analysis received 100 milligrams of Jideytro once daily. They could have previously received up to one line of platinum-based chemotherapy, with or without immunotherapy. Twenty-seven percent of patients had received this treatment before entering the trial.

The median patient age was 59. Most patients (93%) had stage 4 disease, and 17% had cancer that had spread to the brain when they entered the study.

What side effects occurred with Jideytro?

Researchers evaluated side effects among 532 patients with ROS1-positive NSCLC who received Jideytro, including patients who had and had not previously received a ROS1 TKI.

The most common side effects of any severity were swelling in the legs, feet or hands (42%), increased creatine phosphokinase levels (23%), constipation (23%), weight gain (22%) and increased levels of the liver enzyme aspartate aminotransferase (19%). Creatine phosphokinase is an enzyme found primarily in muscles, and higher levels can indicate muscle injury or stress.

The most common severe side effects were weight gain, reported in 7% of patients, and increased creatine phosphokinase levels, reported in 5%.

Side effects led to dose reductions in 12% of patients, while 4% stopped treatment because of side effects.

Is Jideytro approved for ROS1-positive lung cancer?

The Food and Drug Administration (FDA) has approved Jideytro for adults with locally advanced or metastatic ROS1-positive NSCLC who have previously received a ROS1 TKI.

Jideytro remains investigational for patients who have not previously received a ROS1-targeted TKI. Investigators concluded that the ARROS-1 findings support continued study of Jideytro as an earlier treatment option for these patients.

The findings were presented at the International Association for the Study of Lung Cancer (IASLC) 2026 World Conference on Lung Cancer.

References

1. Drilon A, et al. “Zidesamtinib in TKI-naive patients with advanced/metastatic ROS1+ NSCLC: ARROS-1 efficacy and safety data.” Presented at: IASLC 2026 World Conference on Lung Cancer; Sept. 12-15, 2026.
2. “FDA approves zidesamtinib for ROS1-positive non-small cell lung cancer.” FDA. Updated July 24, 2026.

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