Novartis' Del-desiran Misses Primary Endpoint in Phase 3 HARBOR, Rattling DMPK-Targeting Field

Novartis查看公司主页 disclosed Tuesday that its global Phase 3 HARBOR study of del-desiran查看药品详情 in myotonic dystrophy type 1 (搜索)搜索该疾病 (DM1) did not show a statistically significant improvement over placebo on the trial's primary endpoint, video hand opening time (vHOT), a measure of how quickly a patient can open their hand after making a tight fist. The miss leaves the most common form of adult muscular dystrophy without an approved therapy directed at the disease itself and casts uncertainty over a class of agents designed to attack its genetic root cause.

Del-desiran查看药品详情 (delpacibart etedesiran) is an investigational antibody oligonucleotide conjugate (AOC) that pairs an antibody binding transferrin receptor 1 (搜索)搜索该靶点 on muscle cells with a small interfering RNA designed to break down the toxic DMPK (搜索)搜索该靶点 messenger RNA that drives the disease. It carries orphan drug, fast track and breakthrough therapy designations from the FDA and entered Novartis查看公司主页' pipeline through the company's acquisition of Avidity Biosciences查看公司主页, a deal valued at about $12 billion.

Trial Design and the Endpoint That Missed

HARBOR enrolled 159 people aged 16 to 65 with DM1 across nine countries, randomized to receive an intravenous infusion of del-desiran查看药品详情 or placebo every eight weeks for seven doses, with a final assessment at week 54. Alongside vHOT, the study tracked hand grip strength, quantitative muscle testing, activities of daily living and a 10-meter walk and run test.

The primary endpoint is a relatively new measure built to capture myotonia, the delayed muscle relaxation that makes it difficult to release a doorknob, steering wheel or handshake. It is considered clinically meaningful but relatively untested as a regulatory endpoint, which is part of why the result is being read carefully rather than as a verdict on the molecule. One analyst quoted in trade coverage pointed to variability in the hand relaxation test as a possible factor.

Novartis查看公司主页 said it saw evidence of clinical activity in secondary endpoints and exploratory analyses, including muscle strength and daily living activities, and that safety findings were generally consistent with previously reported data. The company has not disclosed numerical results, has not said when it will present the full dataset, and has not indicated whether HARBOR included biomarker analyses. An earlier Phase 1/2 study showed the drug reached skeletal muscle and reduced disease-associated DMPK (搜索)搜索该靶点 RNA.

"Developing therapies for a complex disease like [myotonic dystrophy type 1 (搜索)搜索该疾病] remains challenging, and setbacks are part of scientific progress," said Shreeram Aradhye, Novartis查看公司主页' president of development and chief medical officer. "As we continue to evaluate the full HARBOR dataset, we remain committed to identifying the most appropriate development path for the del-desiran查看药品详情 program and advancing innovative approaches for people living with [myotonic dystrophy] and other serious neuromuscular diseases."

Market Fallout and a Third Setback in a Week

Investors reacted sharply. Novartis查看公司主页 shares fell about 9% in Switzerland, among the worst trading days in the company's history, with one pricing snapshot in Swiss trading showing the stock at 112.66 francs, down 12.80 francs or 10.20%. The decline followed the failure of pelacarsen查看药品详情 in the late-stage HORIZON cardiovascular outcomes study and, about a week earlier, the pause of eight studies of the experimental cell therapy rap-cel after three patient deaths.

Barclays estimated del-desiran查看药品详情 and pelacarsen查看药品详情 together carried roughly $5 billion in risk-adjusted peak sales potential and argued del-desiran doubled as a litmus test for the Avidity acquisition. "We expect shares to materially [underperform], and Novartis查看公司主页' 20% sector premium may now be debated," Barclays wrote. Jefferies told clients the company's growth goal "will likely be perceived as unattainable without further M&A, which is now questionable again." Novartis reiterated guidance of average annual sales growth of 5% to 6% through 2030.

The read-through extended to competitors sharing design features. Reuters reported that shares of Dyne Therapeutics查看公司主页 and Sarepta Therapeutics查看公司主页 fell 30% and 15.5% in U.S. premarket trading, with BioPharma Dive later reporting Dyne down 22% and Novartis查看公司主页 more than 13% intraday. Sarepta's candidate is also a small interfering RNA aimed at DMPK (搜索)搜索该靶点 RNA using a different targeting approach, while Dyne's therapy uses a similar muscle-targeting antibody strategy with overlapping functional endpoints.

Dyne's Z-Basivarsen Under Scrutiny

Dyne Therapeutics查看公司主页' Z-Basivarsen (搜索)搜索该药品 (DYNE-101查看药品详情) is an antisense oligonucleotide conjugated to an antigen-binding fragment that binds transferrin receptor 1 (搜索)搜索该靶点, enabling delivery to muscle and the central nervous system. The company has enrolled 71 patients in the registrational expansion cohort of its Phase 1/2 ACHIEVE trial, with topline results expected in the first quarter of 2027. A Phase 3 confirmatory trial, HARMONIA, initiated in March and aligned with the FDA on design and protocol, will enroll approximately 150 participants age 16 and older and is intended to support conversion of Accelerated Approval to traditional approval in the U.S. and ex-U.S. marketing applications.

Dyne shares fell 4.2% on Wednesday after cratering more than 16% a day earlier, yet the stock remains up about 5.5% year to date. Analysts trimmed targets while maintaining constructive ratings: Morgan Stanley cut to $36 from $45 (Overweight), RBC Capital to $30 from $35 (Outperform) and Baird to $26 from $30 (Outperform). RBC cautioned against directly applying Novartis查看公司主页' results to Dyne, pointing to differences in how the two drugs target transferrin, their payloads and their clinical trial designs. The consensus price target stands at $37.53, with 16 of 17 analysts rating the stock a Buy and one a Sell, according to Koyfin.

Dyne said it will present additional one-year clinical data from ACHIEVE at the Annual International Congress of the World Muscle Society and the 2026 Annual Meeting of the American Association of Neuromuscular & Electrodiagnostic Medicine, including six- and 12-month data from a pooled dose group of 25 to 26 participants and 12-month data from a propensity-matched natural history cohort of 41 to 46 participants.

A Multisystem Disease With No Approved Therapy

DM1 is caused by an expanded stretch of CTG repeats in the DMPK (搜索)搜索该靶点 gene and is inherited in an autosomal dominant pattern, giving a parent with the condition a 50% chance of passing it to each child. The National Human Genome Research Institute describes it as a multisystem disorder rather than a muscle disease alone: beyond weakness and myotonia, it can involve cardiac conduction problems, breathing difficulties during sleep, early cataracts, insulin resistance, gastrointestinal symptoms, excessive daytime sleepiness and cognitive effects. Cardiac and respiratory complications are the leading causes of death.

Prevalence estimates have long ranged from five to 20 cases per 100,000 people, but a study published in Neurology that screened de-identified newborn blood spots from New York State found CTG repeat expansions in DMPK (搜索)搜索该靶点 up to five times more common than those estimates suggested, at roughly one in 2,100 births. The authors concluded the disease is likely underdiagnosed, and diagnostic delays measured in years are common. Larger expansions are generally associated with earlier onset and a more severe course, with the largest linked to childhood and congenital forms; repeats also tend to lengthen when passed between generations.

Pipeline Context and Next Steps

Novartis查看公司主页 said it is conducting a comprehensive evaluation of the full HARBOR dataset and plans to engage with health authorities to determine the most appropriate development path for del-desiran查看药品详情. The candidate is one of three AOC therapies added through the Avidity acquisition. Novartis is advancing delpacibart zotadirsen查看药品详情 (del-zota) for Duchenne muscular dystrophy patients with mutations amenable to exon 44 skipping, with an accelerated approval filing granted Priority Review, and plans to meet with the FDA on delpacibart braxlosiran查看药品详情 (del-brax) in facioscapulohumeral muscular dystrophy following positive Phase 1/2 biomarker data. Jefferies said conviction on del-brax is unlikely before Phase 3 data expected in 2028.

The pelacarsen查看药品详情 failure came in HORIZON, which did not meet its primary endpoint of reducing the risk of cardiovascular events — a composite of cardiovascular death, non-fatal myocardial infarction, non-fatal stroke and urgent coronary revascularization requiring hospitalization — versus placebo, though lower lipoprotein(a) levels were achieved in a population receiving guideline-directed lipid-lowering and antihypertensive therapy. Novartis查看公司主页 licensed pelacarsen from Ionis Pharmaceuticals查看公司主页 in February 2019; Ionis shares also declined on the news.

Not all recent readouts were negative. Novartis查看公司主页 reported positive top-line results from the late-stage REMODEL-1/-2 studies of remibrutinib查看药品详情 in relapsing multiple sclerosis, where the highly selective oral Bruton's tyrosine kinase inhibitor significantly reduced annualized relapse rate versus Aubagio in the targeted population and showed a clinically meaningful delay in disability progression. Remibrutinib 25 mg is already approved as Rhapsido by the FDA in September 2025 and the EMA in April 2026 for adults with chronic spontaneous urticaria.

For patients, the HARBOR result does not change current clinical care. Del-desiran查看药品详情 was available only through trials, so no prescription is disrupted; what changed is the timeline, with a therapy many expected to reach the market within a couple of years now delayed and unresolved. Clinicians continue to emphasize cardiac monitoring including periodic ECGs, sleep and respiratory assessment, eye examinations and diabetes screening, along with continued use of medications prescribed for symptoms such as myotonia or daytime sleepiness. Anesthesia warrants particular attention, as people with DM1 face elevated risk of respiratory and cardiac complications during and after surgery, including procedures as routine as a colonoscopy. An open-label extension for HARBOR participants is listed on ClinicalTrials.gov.

Whether the molecular-to-clinical chain broke at the endpoint or the drug failed more broadly remains unresolved. Novartis查看公司主页 reported activity on secondary measures, leaving open the possibility that the trial measured the wrong thing rather than that the approach did nothing — a question that will not be settled until the full dataset is presented or published.