Last updated: August 3, 2026
Zidesamtinib (Jideytro, formerly NVL-520) is the first ROS1-selective tyrosine kinase inhibitor (TKI), developed by Nuvalent. It targets the abnormal ROS1 kinase that drives ROS1-positive non-small cell lung cancer (NSCLC), while being designed to spare the related TRK kinases that cause some of the neurologic side effects of earlier ROS1 drugs. Dosing: oral (by mouth).
Mechanism of action:ROS1 gene rearrangements produce an always-on kinase that fuels cancer growth. Zidesamtinib is a macrocyclic, ROS1-selective inhibitor engineered to block ROS1 — including the G2032R resistance mutation that limits earlier TKIs — and to penetrate the brain, where ROS1+ lung cancer frequently spreads.
Regulatory status:FDA-approved July 22, 2026 for adults with locally advanced or metastatic ROS1-positive NSCLC previously treated with a ROS1 TKI, based on the ARROS-1 trial (NCT05118789).
About 1–2% of non-small cell lung cancers are driven by a rearrangement (a "fusion") involving the ROS1 gene. That may sound rare, but it defines a distinct group of patients — often younger, frequently never-smokers — whose cancer depends on a single, targetable switch. Blocking ROS1 with a pill can control these cancers, sometimes for years.
The problem this drug solves. Two challenges have limited earlier ROS1 drugs (crizotinib, entrectinib, repotrectinib, taletrectinib). First, most of them also block a related family of kinases called TRK, which contributes to side effects like dizziness, cognitive or mood changes, and weight gain. Second, over time the cancer often develops a specific resistance mutation, G2032R, that changes the shape of ROS1 so those drugs no longer fit — and the cancer, frequently including brain metastases, starts to grow again.
What's new. Zidesamtinib was purpose-built to answer both problems: it is selective for ROS1 (largely sparing TRK, with the goal of fewer neurologic side effects), it was designed to stay active against G2032R, and it is brain-penetrant. On July 22, 2026, the FDA approved it for ROS1+ NSCLC patients whose cancer has already progressed on a prior ROS1 TKI — exactly the setting where a next-generation, resistance-aware option was most needed.
Zidesamtinib's approval is in ROS1-positive NSCLC, in the previously-treated (post-ROS1-TKI) setting.
Previously-Treated ROS1-Positive NSCLC (NEW — July 22, 2026)
★ First-in-Class: A ROS1-Selective TKI Built for Resistance and the Brain
Zidesamtinib is the first ROS1-selective tyrosine kinase inhibitor. Where earlier ROS1 drugs are multi-target inhibitors that also block TRK (and sometimes ALK), zidesamtinib was engineered to hit ROS1 specifically. That selectivity is the point: sparing TRK is intended to reduce the neurologic side effects associated with the drug class, while the molecule was designed to remain active against the G2032R solvent-front mutation — the most common on-target reason ROS1+ lung cancer stops responding to prior TKIs — and to penetrate the central nervous system for brain metastases.
The result is a drug positioned squarely for the previously-treated patient: someone whose ROS1+ NSCLC has progressed on a first ROS1 TKI, often with new or growing brain disease, who previously had limited targeted options.
Curated set of recruiting ROS1-targeted trials in the ClinTrialFinder corpus as of August 2026. Zidesamtinib's own pivotal study (ARROS-1) is still enrolling; it is surrounded by a maturing field of next-generation and multi-target ROS1 TKIs. Statuses are as recorded in the corpus and can change — verify on ClinicalTrials.gov.
In ROS1-positive cancers, part of the ROS1 gene becomes fused to another gene. The resulting protein is an always-on kinase — a molecular switch stuck in the "grow" position — that drives the cancer. ROS1 TKIs work by fitting into the kinase's active site and switching it off.
What sets zidesamtinib apart is selectivity. Its macrocyclic (ring-shaped) design was optimized to bind ROS1 tightly while largely avoiding the closely related TRK kinases (encoded by the NTRK genes). Because TRK plays a role in the nervous system, drugs that inhibit it can cause dizziness, cognitive or mood changes, and weight gain; sparing TRK is intended to reduce those effects. The same design goals gave zidesamtinib two further properties that matter clinically: retained activity against the ROS1 G2032R "solvent-front" resistance mutation (which blunts earlier TKIs), and the ability to cross into the brain to act on central-nervous-system metastases. Together, these make it a targeted option specifically for patients whose cancer has grown resistant to a prior ROS1 TKI.
As an oral ROS1-selective TKI, zidesamtinib's tolerability profile reflects its design goal of sparing TRK, which is intended to reduce the neurologic side effects (such as dizziness and cognitive or mood changes) associated with less-selective ROS1/TRK inhibitors. As with the drug class generally, patients may still experience effects such as changes in taste, swelling (edema), constipation, fatigue, and laboratory changes including liver-enzyme or blood-count abnormalities; your oncology team monitors bloodwork and symptoms and adjusts the dose as needed. Zidesamtinib is taken by mouth.
This section is a general, plain-language overview and is not a complete list of side effects. For the authoritative safety information — including warnings, monitoring, and drug interactions — refer to the FDA-approved prescribing information and discuss your individual risks with your oncologist.
Zidesamtinib is approved for ROS1+ NSCLC that has progressed on a prior ROS1 TKI — the second-line (or later) targeted setting. Its differentiators (G2032R activity, brain penetration, TRK-sparing selectivity) are most relevant precisely there: after a first ROS1 inhibitor stops working, often with brain involvement. First-line ROS1+ NSCLC is currently treated with other ROS1 TKIs, and several trials above are testing next-generation agents earlier in the course (including adjuvant and first-line studies). For the disease-level view of ROS1+ and other targetable lung-cancer subtypes, see the NSCLC trials page.
What is zidesamtinib (Jideytro) and how does it work?
Zidesamtinib (Jideytro, formerly NVL-520) is the first ROS1-selective tyrosine kinase inhibitor (TKI), from Nuvalent. In ROS1-positive lung cancer, a rearranged ROS1 gene makes an always-on kinase that drives the cancer. Zidesamtinib is an oral pill that blocks that ROS1 kinase. It was designed to be selective for ROS1 while sparing the related TRK kinases (a source of neurologic side effects with earlier drugs), to reach the brain, and to stay active against the G2032R resistance mutation.
What is zidesamtinib FDA-approved for?
On July 22, 2026, the FDA approved zidesamtinib for adults with locally advanced or metastatic ROS1-positive NSCLC who have already been treated with a ROS1 TKI — that is, patients whose ROS1+ lung cancer has progressed on a prior ROS1-targeted therapy. The approval was based on the ARROS-1 trial (NCT05118789).
How is it different from crizotinib, entrectinib, repotrectinib, or taletrectinib?
Those earlier ROS1 inhibitors also block other kinases — most notably TRK, and in some cases ALK. Blocking TRK contributes to side effects like dizziness, cognitive or mood changes, and weight gain. Zidesamtinib was engineered to be ROS1-selective — hitting ROS1 while largely sparing TRK — with the goals of fewer neurologic side effects, activity against the G2032R resistance mutation that limits earlier TKIs, and good penetration into the brain.
What is the ROS1 G2032R mutation, and why does it matter?
G2032R is a "solvent-front" resistance mutation in the ROS1 kinase and the most common way ROS1+ lung cancer becomes resistant to earlier ROS1 TKIs — it changes the target's shape so those drugs no longer bind well. Zidesamtinib was specifically designed to remain active against ROS1 including the G2032R-mutant form, which is central to its role after a prior ROS1 TKI has stopped working.
Are there clinical trials of zidesamtinib and other ROS1 therapies I can join?
Yes. The pivotal ARROS-1 trial (NCT05118789) is still recruiting patients with advanced ROS1-positive NSCLC and other ROS1-positive solid tumors. The broader recruiting ROS1-targeted NSCLC landscape includes repotrectinib (TRIDENT-1, NCT03093116; NCT06315010), taletrectinib (NCT06564324; adjuvant NCT07154706), and JYP0322 (NCT06128148), among others. Eligibility depends on your exact diagnosis, biomarker, prior treatments, and other factors — use the trial matcher to see which fit your situation.
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