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# Why Delaying Brain Relapse Was Not Enough for the FDA
- URL: https://www.bioreview.com/why-delaying-brain-relapse-was-not-enough-for-the-fda/
- Published: 2026-11-09T14:05:04.000Z
- Updated: 2026-11-10T14:02:38.000Z
- Description: The FDA issued a Not Approvable Letter for Novocure's Optune Mya in lung cancer brain metastases, citing uncertainty about the degree of clinical benefit despite a phase 3 win on time to intracranial progression.
- Author: BioReview Admin
- Tags: Policy, Pharmaceuticals

On November 9, 2026, Novocure [announced](https://www.businesswire.com/news/home/20261109483647/en/?ref=bioreview.com) that the Food and Drug Administration had issued a Not Approvable Letter for its Premarket Approval application for Optune Mya. The device was intended for adult patients with brain metastases from non-small cell lung cancer following stereotactic radiation. The FDA determined that uncertainty around the degree of clinical benefit provided by Optune Mya prevented approval. The agency raised no concerns about safety. Novocure shares were down about 2% in premarket trading.

The letter is a statement about evidence standards. The phase 3 METIS [trial](https://www.sec.gov/Archives/edgar/data/1645113/000164511324000009/specialreportprmarch2024.htm?ref=bioreview.com) enrolled 298 adult patients with 1 to 10 brain metastases from non-small cell lung cancer and randomized them after stereotactic radiosurgery to Tumor Treating Fields therapy plus supportive care or supportive care alone. The primary endpoint was time to first intracranial progression. Patients treated with Tumor Treating Fields plus supportive care had a median time to intracranial progression of 21.9 months versus 11.3 months with supportive care alone (hazard ratio 0.67, P=0.016). That delay did not, on this record, settle the question of clinical benefit the agency raised in the letter.

### The labeling endpoints did not come through

Median Tumor Treating Fields treatment duration in METIS was 16 weeks, and median usage was 67%. Preliminary analyses of key secondary endpoints, time to neurocognitive failure, overall survival, and radiological response rate, did not demonstrate statistical significance. Those key secondary endpoints were planned to be used in labeling claims if successful. Patients with known tumor mutations for which targeted agents are available were excluded. Patients could cross over to Tumor Treating Fields after confirmation of second intracranial progression, a design that can complicate overall survival even when intracranial control looks cleaner on the primary clock.

That is the gap the letter occupies. Tumor Treating Fields can push out the time to first brain relapse after radiosurgery and still leave the FDA unwilling to approve, if the analyses meant to underwrite a benefit claim on survival, cognition, and response do not reach significance. Safety was not the disputed point. Degree of clinical benefit was. For a Premarket Approval file, that distinction is the whole decision.

### Glioblastoma evidence included survival

Novocure's original Optune approval rests on the EF-14 trial in newly diagnosed glioblastoma. That study enrolled 695 [patients](https://pmc.ncbi.nlm.nih.gov/articles/PMC5820703/?ref=bioreview.com) and compared Tumor Treating Fields plus temozolomide with temozolomide alone. Median progression-free survival was 6.7 months versus 4.0 months. Median overall survival was 20.9 months versus 16.0 months. The hazard ratio was 0.63, with P less than .001 for both endpoints. EF-14 therefore put two statistically significant time-to-event results in front of the agency, including overall survival. METIS put one statistically significant intracranial-progression result in front of the agency, with no statistically significant findings on the key secondaries reserved for labeling.

### A larger population and a meeting, not a new study

Approximately 25% of patients with non-small cell lung cancer have brain metastasis at diagnosis, and lifetime risk is approximately 50%. That burden is why extending Tumor Treating Fields beyond glioblastoma into this population has been the growth case, and why a Not Approvable Letter here is more than a missed niche indication. Novocure plans to meet with the FDA to determine options that would support approval without additional clinical studies. The company said there is no assurance these discussions will lead to approval.

A path that does not require a new trial implies the remaining argument is about how to read METIS as it stands. The primary endpoint already hit. The key secondaries already missed in preliminary analyses. Crossover after second intracranial progression is already in the protocol. Mutation-positive patients who have targeted agents available are already outside the randomized set. If that meeting cannot convert the existing file into an approvability path, the option the company is trying to avoid is another study aimed at the endpoints the first one did not win.

The open question is the standard itself. For a device used after stereotactic radiosurgery, is a statistically significant delay in intracranial progression enough clinical benefit when overall survival, time to neurocognitive failure, and radiological response do not reach significance in the same trial? The FDA's answer, in the form of this letter, was that the uncertainty around the degree of benefit was disqualifying as filed. Until Novocure and the agency agree on another reading of the same dataset, Optune Mya remains unapproved for brain metastases from non-small cell lung cancer, despite a primary endpoint that favored treatment and a safety review that raised no concerns.