Novartis Stock Falls 10% After Second Drug Trial Setback

Key Takeaways

• Novartis stock fell about 10% after del-desiran failed to meet the primary endpoint in a Phase III trial.
• The result followed the recent failure of cardiovascular drug pelacarsen, increasing concerns about the company’s pipeline.
• Vontobel cut its Novartis price target to CHF125 after removing $3 billion in potential peak sales for del-desiran.

Novartis Stock Drops as Del-Desiran Misses Trial Goal

Novartis stock dropped about 10% in Zurich trading on Tuesday, September 8, after the Swiss pharmaceutical company reported disappointing Phase III results for delpacibart etedesiran, also known as del-desiran.

The shares fell to approximately CHF112.56, extending their five-day decline to more than 14%. The sharp market reaction reflects concerns about Novartis’s ability to develop new medicines as some of its established products face increasing competition and future patent expirations.

Del-desiran is an experimental treatment for myotonic dystrophy type 1, or DM1. The genetic disease can cause muscle stiffness, weakness and impaired hand function. There are currently no approved treatments targeting the underlying cause of DM1.

The drug was acquired through Novartis’s $12 billion purchase of Avidity Biosciences, making it an important part of the company’s neuromuscular pipeline.

What Happened in the HARBOR Trial?

The Phase III HARBOR study tested del-desiran in approximately 150 patients with DM1 over 54 weeks. Participants received the treatment or a placebo every eight weeks.

The trial’s primary endpoint was video hand-opening time, a measurement used to assess hand myotonia. Del-desiran did not produce a statistically significant improvement over placebo on this measure.

Missing a primary endpoint creates a major challenge for a drug’s approval prospects. However, Novartis reported signs of clinical activity across some secondary endpoints and exploratory analyses. The treatment’s safety profile was also generally consistent with previous studies.

Novartis will evaluate the complete dataset and consult health authorities before determining whether to continue, modify or discontinue the program.

Pelacarsen Failure Increases Pipeline Concerns

The del-desiran result followed another important Phase III setback involving pelacarsen, an experimental cardiovascular medicine.

The Lp(a)HORIZON trial involved 8,323 patients with elevated lipoprotein(a) and established cardiovascular disease. Pelacarsen successfully reduced Lp(a) levels but failed to significantly lower the risk of cardiovascular death, heart attack, stroke and urgent coronary procedures compared with placebo.

The two failures have raised concerns about the ability of Novartis’s pipeline to support future growth. The company needs successful new medicines to compensate for increasing generic competition affecting older products, including heart-failure treatment Entresto.

Novartis still has several major commercial growth drivers, including Kisqali, Kesimpta, Pluvicto, Scemblix and Leqvio. However, repeated late-stage disappointments may cause investors to assign lower valuations to experimental products that have not completed pivotal trials.

Avidity Acquisition Faces Greater Scrutiny

Novartis completed its acquisition of Avidity Biosciences in February 2026. The transaction valued Avidity at approximately $12 billion on a fully diluted basis and added three late-stage neuromuscular programs to the Novartis pipeline.

Because del-desiran was the most advanced of these treatments, the HARBOR failure has raised questions about the expected return from the acquisition.

Vontobel removed approximately $3 billion in potential peak annual del-desiran sales from its valuation model. The brokerage subsequently lowered its Novartis price target from CHF128 to CHF125.

The acquisition still includes two other important experimental drugs. Delpacibart zotadirsen, or del-zota, is being developed for a form of Duchenne muscular dystrophy and has received priority review from the US Food and Drug Administration.

Delpacibart braxlosiran, or del-brax, is being studied as a treatment for facioscapulohumeral muscular dystrophy. Novartis plans to discuss the program with the FDA following positive early-stage biomarker results.

Progress from these two assets could preserve some of the strategic value of the Avidity acquisition, although both remain exposed to clinical and regulatory risks.

Novartis Maintains Its Long-Term Guidance

Despite the latest trial failure, Novartis maintained its target for net sales to grow at a compound annual rate of 5% to 6% at constant currencies between 2025 and 2030.

The company expects growth to be supported by existing medicines, new indications and future product launches. Novartis has identified more than 30 potential high-value pipeline assets and previously projected more than 15 potentially submission-enabling trial results over two years.

Maintaining the guidance may provide some reassurance, but the recent setbacks have reduced the company’s margin for further clinical disappointments. Investors will watch whether established products can deliver enough growth to offset failed programs and declining contributions from older medicines.

Novartis may also need to rely more heavily on licensing agreements or acquisitions to strengthen its pipeline. Such transactions could create new growth opportunities but would introduce additional valuation and execution risks.

What Could Move Novartis Stock Next?

The full HARBOR dataset will be the immediate focus for Novartis stock. Investors will examine whether improvements in secondary endpoints were consistent, clinically meaningful and concentrated in particular patient groups.

Feedback from regulators will also be important. Positive secondary results do not automatically compensate for a failed primary endpoint, but they could influence whether Novartis conducts further analysis or launches another trial.

Other potential catalysts include FDA progress for del-zota, future clinical results for del-brax and sales growth from major products such as Kisqali, Kesimpta and Pluvicto.

The 10% decline suggests that investors have substantially reduced the expected value of del-desiran. The stock’s next direction may depend on whether the broader pipeline can restore confidence in Novartis’s 2025–2030 growth strategy.