Novartis Shares Plunge 10% in Zurich Trading After Second Pivotal Drug Trial Fails in a Week

Since Novartis disclosed on Friday, September 4 that its Lp(a) cholesterol drug pelacarsen failed to reduce heart attacks and strokes in the Lp(a)HORIZON trial, the company has delivered a second pivotal-trial disappointment in the same week. Novartis said Tuesday, September 8 that del-desiran, its experimental neuromuscular therapy for myotonic dystrophy type 1, missed its primary objective in a late-stage study, according to Dow Jones Newswires reporting carried by Morningstar.

Shares slid 10% shortly after the opening bell Tuesday on the Swiss exchange, according to Morningstar's report by Adria Calatayud. If that drop holds through the close, FactSet data cited by Morningstar shows it would be Novartis's worst one-day percentage decline since 1987, wiping out most of the stock's gains for the year.

Two out of three misses in one week

Morningstar's reporting frames the count plainly: two of the three pivotal studies Novartis released results for over the past week fell short of their main targets. Pelacarsen failed to cut cardiovascular events. Del-desiran failed its primary endpoint. Only a multiple-sclerosis pill succeeded, a result Jefferies analysts said, per Reuters reporting carried by WKZO and Euronext, "should make the conclusion of the pelacarsen study more palatable" for investors.

Del-desiran was the most advanced drug candidate Novartis picked up through its $12 billion acquisition of Avidity Biosciences, completed in February, according to Morningstar. Barclays analysts had said success in the muscle-disease trial "is needed to justify" that price tag, per the Reuters report carried by WKZO.

The trial measured how long it took patients with myotonic dystrophy type 1 to open their hand after gripping. Del-desiran did not show significant improvement over placebo on that measure, Novartis said. The company reported the drug showed "evidence of clinical activity for other objectives" and that safety data were generally consistent with prior studies. Novartis said it is evaluating the full dataset and will discuss the path forward with health authorities.

Jefferies analysts wrote that the failure means investor concerns about Novartis's growth prospects beyond 2030 will resurface, according to Morningstar. Novartis reiterated its guidance of 5% to 6% annual sales growth for the 2025-to-2030 period despite the setback.

The pelacarsen backdrop still weighing on the stock

The del-desiran news lands on top of last week's pelacarsen failure, which already cost Novartis roughly 3% on Monday, September 7, according to Reuters reporting from Bhanvi Satija carried by WKZO and Euronext. Ionis Pharmaceuticals, Novartis's partner on pelacarsen, lost 10% of its value on the same news, Pharmaphorum reported.

That failure also rattled Amgen and Eli Lilly, both of which are running their own late-stage trials of Lp(a)-lowering drugs, olpasiran and lepodisiran respectively. MarketBeat reported Amgen shares pulled back as the Novartis miss "raised concerns" about olpasiran, though the site noted its data covers Amgen sentiment rather than the Novartis situation directly. Analysts at BMO Capital Markets and William Blair, cited by BioSpace, said the pelacarsen result "raises the burden of proof" for both rival drugs, while cautioning that trial design differences involving deeper Lp(a) reduction and higher-risk patient populations could still let Amgen's and Lilly's drugs succeed where Novartis's did not.

Why it matters for the patent cliff

Novartis has been counting on new drugs to offset what CEO Vas Narasimhan has called the steepest patent cliff in the company's history. Its top-selling heart drug Entresto peaked at nearly $8 billion in sales in 2024 and brought in under $2.5 billion in the first half of 2026 after losing patent exclusivity, according to Pharmaphorum. The company has said it expects roughly $4 billion in lost sales from patent expiries.

The strongest case for patience is made by Novartis's own chief medical officer Shreeram Aradhye regarding the pelacarsen data. A single trial miss doesn't necessarily kill an entire drug class or a company's broader pipeline. Aradhye called the pelacarsen results "important evidence that advances scientific understanding" even in failure, and Novartis is still awaiting fourth-quarter data on remibrutinib in skin disease and continuing to advance two other Avidity-derived drug candidates.

What remains unresolved is what Novartis does next with del-desiran itself. The company has not said whether it will pursue a narrower regulatory pathway based on the "other objectives" where it says the drug showed activity, or whether discussions with health authorities could still lead to an approval filing. Full pelacarsen data, meanwhile, is still pending presentation at a future medical congress that Novartis has not yet dated, meaning the scope of both setbacks won't be fully clear until that data and any regulatory conversations play out.