Novocure Shares Plunge 18% After Key Glioblastoma Trial Fails to Show Survival Benefit

Novocure’s TRIDENT Phase 3 trial was specifically designed to test whether starting Tumor Treating Fields (TTFields) therapy during chemoradiation improves outcomes versus initiating during the maintenance phase; 981 patients were enrolled and randomized shortly after surgery. In the intent-to-treat analysis, the trial reported a hazard ratio of 0.953 with a p-value of 0.519—supporting that the overall survival difference was not statistically significant.
Although TRIDENT missed its primary overall-survival endpoint, Novocure said earlier use of TTFields was “feasible and well tolerated,” with device-related adverse events staying consistent with prior TTFields studies.
The selloff included specific trading details reported by RTT News: shares fell about 18.16% to $14.51 on the Nasdaq, and the stock was trading within a 52-week range of $9.82 to $18.92.
GuruFocus provided additional financial context beyond “not profitable,” including that Novocure’s earnings per share were -1.53 and that the stock’s price-to-sales (P/S) ratio was 2.43 (with no P/E available).
NovoCure's stock plunged nearly 20% on June 18, 2026, after its Phase 3 TRIDENT trial failed to show that its electric-field cancer therapy helps brain cancer patients live longer. Shares fell 18.16% to $14.51 on the Nasdaq, according to RTT News, wiping out hundreds of millions of dollars in market value in a single session.
The TRIDENT trial enrolled 981 glioblastoma patients to test whether starting Tumor Treating Fields — a therapy that uses electric fields to disrupt cancer cell division — during chemotherapy and radiation was better than starting it later. The answer was essentially no. Median survival was 17.7 months in the treatment group versus 17.5 months in the control group, a difference so small it was almost certainly due to chance, RTT News reported.
The statistics from the TRIDENT trial told a brutal story. The hazard ratio — a measure of how much the treatment reduced the risk of death — was 0.953, barely below 1.0. The p-value was 0.519, far above the 0.05 threshold required to call a result statistically significant. In plain terms, a p-value that high means there is a 51.9% chance the tiny survival difference was pure random noise, according to GuruFocus.
The trial had been designed to test a specific scientific idea: that TTFields would make cancer cells more sensitive to radiation, creating a stronger combined effect. That synergy never showed up in the data. NovoCure CEO Asaf Danziger said the company was "disappointed that the TRIDENT trial did not reach its primary endpoint," but stressed that the therapy remained safe and "feasible" to use alongside radiation.
NovoCure started the TRIDENT trial in December 2018. It took roughly five years to enroll 981 patients across international sites. The company was building on its earlier EF-14 trial, which won FDA approval for Optune — its TTFields device — in the maintenance phase of glioblastoma treatment, meaning after radiation ends. TRIDENT was designed to push that starting point earlier, according to Seeking Alpha.
Glioblastoma is one of the deadliest brain cancers. The standard treatment — surgery, then chemoradiation, then maintenance chemotherapy — has barely changed in 20 years. A survival benefit of just 0.2 months will not change that standard of care. The FDA is also unlikely to approve TTFields for concurrent use with radiation based on these results, which closes off a key piece of NovoCure's growth plan in the brain cancer market.
NovoCure was already in a fragile financial position before the trial news broke. The company is not profitable, with earnings per share of -1.53 and no price-to-earnings ratio available. Its price-to-sales ratio sits at 2.43, according to GuruFocus, which also assigned the stock a GF Score of 70 out of 100 — described as "fair" performance relative to peers.
Making matters worse, GuruFocus reported that NovoCure insiders sold roughly $0.9 million worth of shares in the 90 days before the announcement. Insider selling ahead of a major trial failure often fuels distrust among investors, even when such sales are pre-scheduled. The stock's 52-week range runs from $9.82 to $18.92, meaning the post-trial price of $14.51 sits uncomfortably close to the bottom.
With the GBM expansion story effectively closed, NovoCure is expected to shift its focus to other cancers. The company already sells Optune Lua, a TTFields device approved for lung cancer treatment. Upcoming data readouts for non-small cell lung cancer and pancreatic cancer are now the most important remaining catalysts for the stock, according to Yahoo Finance.
Executive Chairman William Doyle said the company would keep "analyzing the TRIDENT data to understand specific subgroups that may have benefited." Analysts at major brokerages called the failure a "significant blow to the bull case" for the stock. Without a profitable earnings base to anchor it, NovoCure's valuation now rests almost entirely on whether TTFields can prove itself in cancers beyond glioblastoma.
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