The French drugmaker Servier said on Tuesday that sevasemten, an experimental pill it bought in June, failed to slow Becker muscular dystrophy in a long trial that compared it with a placebo (a dummy pill)1. Servier paid $1.55 billion in cash for the drug, plus about $1 billion more in possible milestone payments, according to STAT1. The drug was originally developed by Edgewise Therapeutics1.
STAT called the result a surprising setback for both Servier and patients, because people with Becker muscular dystrophy currently have no approved treatments1. The same drug had previously shown promising results in a smaller study in which patients were randomly assigned to the drug or a placebo1.
What happened
The trial is called GRAND CANYON1. In a statement, Servier did not hide that the outcome clashed with what came before:
“The results of the pivotal GRAND CANYON study are not aligned with certain findings observed in prior clinical studies.”
That statement was reported by STAT1. The company added that it “is conducting a comprehensive analysis of the GRAND CANYON study dataset, together with relevant prior clinical data, to better understand and further characterize the study findings”1.
Servier has not released the detailed numbers. What is known so far comes from its short statement and from earlier descriptions of the trial by Edgewise and in a public trial registry.
What the trial was testing
Sevasemten is a pill, a small chemical drug taken by mouth, designed to prevent the muscle damage that happens when muscles contract in people with Becker and a related disease, Duchenne muscular dystrophy2. Edgewise described it as a “fast skeletal myosin inhibitor,” meaning it acts on a motor protein inside fast-twitch muscle fibers to protect them from damage caused by their own contractions3.
GRAND CANYON enrolled 175 adults with Becker muscular dystrophy across 12 countries, finished enrollment in February 2025, and followed each person for 18 months3. Its main goal was the change in a score called the North Star Ambulatory Assessment, a measure of physical function, compared with placebo3. The public trial registry lists the same main goal: the change from the start of the study in the total North Star score at 18 months4. The registry also lists side effects, counted and graded, as main outcomes4.
The trial was “double-blind,” meaning neither patients nor doctors knew who got the drug and who got the dummy pill4. Edgewise had said the trial was “highly powered,” meaning it was large enough to detect a real difference in the North Star score over 18 months if one existed3.
One labeling detail differs between sources. STAT describes GRAND CANYON as a Phase 3 trial, the last big stage of testing before a drug can be approved1. The registry lists the overall study as Phase 2, with GRAND CANYON as an added “pivotal cohort,” a group of patients meant to provide the main evidence for approval4. The registry shows the study as completed, with its main data collection finished on September 7, 2026, and 244 people enrolled across all its groups4.
The earlier, smaller results
GRAND CANYON grew out of an earlier study called CANYON, which looked at safety, physical function and blood signs of muscle damage in adult men with Becker2. In 2024, when CANYON was fully enrolled, Edgewise expanded it to add a pivotal group of adults that became GRAND CANYON2. The 2024 announcement planned for 120 additional participants2, and the final group reached 1753.
For the earliest CANYON groups, the main measure in the registry was creatine kinase, a substance that leaks into the blood when muscle is damaged, averaged over months 6, 9 and 124. This is a sign of muscle damage in the blood, not a direct measure of how well someone walks or climbs stairs. The new failure was on the physical function score.
STAT reports that the smaller study’s results had been promising1, but the sources available here do not give its numbers, so Biohack cannot say exactly what it showed or how large any effect was.
What this does not show yet
Several important questions remain open because Servier has released only a brief statement:
- How large the difference between the drug and placebo was, and whether any group of patients appeared to do better.
- How the drug affected the blood signs of muscle damage in this larger trial.
- What the safety results were. The registry lists side effects as a main outcome, but no results have been posted4.
- Why the result differs from earlier studies. Servier says that is what its ongoing analysis is meant to find out1.
A failed main goal means the trial did not show the benefit it was designed to show. It does not, on its own, explain why. Until the full data are published and reviewed by outside experts, the reasons stay unknown.
Who is behind it
Edgewise Therapeutics, based in Boulder, Colorado, developed sevasemten and sponsored the trial, according to the registry4. Servier bought the drug from Edgewise in June1.
Before the readout, Edgewise was openly preparing for success. In November 2025, chief executive Kevin Koch said, “Planning for success in GRAND CANYON, we are building the commercial infrastructure to support a potential launch of sevasemten in Becker”3. The company had said it expected to report the main results in the last quarter of 20263, which is when Servier’s announcement came.
The drug also had regulatory support before this result. The U.S. Food and Drug Administration had granted it orphan drug status (incentives for rare diseases) and Fast Track status (a faster review path) for Becker and Duchenne, and Europe’s medicines regulator granted it orphan status for both diseases in April 20242. These designations help a drug’s development; they are not approvals and do not mean a drug works.
Becker muscular dystrophy and the wider program
Becker muscular dystrophy is a rare, genetic disease that mostly affects males, according to Edgewise’s description2. Muscles are damaged when they contract, and that damage drives muscle loss and declining movement2. Once muscle is lost, the decline in function cannot be reversed, and some people develop heart failure from damage to the heart muscle, which can lead to a heart transplant or early death2.
Interest among patients was high. Edgewise said that as of September 2025, 99% of eligible participants from its Becker studies had joined MESA, a follow-on study in which everyone receives the drug and long-term safety is tracked3. What happens to that study now has not been stated in the sources.
Sevasemten was also being tested in boys with Duchenne muscular dystrophy, a more severe related disease2. One of those studies, LYNX, enrolled 76 children and is listed as active but no longer recruiting, with main data collection expected in January 20275. In late 2025, Edgewise said it planned to discuss a larger Duchenne trial with the FDA and hoped to start one in 20263. The sources do not say whether the Becker result changes those plans.
What to watch next
- Full results. The detailed numbers, including safety, have not been posted to the trial registry yet4.
- Servier’s analysis. The company says it is reviewing GRAND CANYON together with earlier data1. Its conclusions will shape whether the drug continues in Becker.
- Duchenne plans. Whether the Duchenne studies move ahead, including the planned larger trial3.
- Patients in the follow-on study. What happens to people still taking the drug in the long-term extension3.
For now, the only firm fact is the one Servier announced: in its largest and longest test, the pill did not slow Becker muscular dystrophy compared with a dummy pill1.
