Novartis drops after Avidity-acquired muscle-drug trial miss

Novartis shares fell sharply after del-desiran, an RNA therapy acquired in its roughly $12 billion purchase of Avidity Biosciences, failed the Phase III HARBOR study in myotonic dystrophy type 1 (DM1). Reuters reported an intraday decline of about 10%; other reports cited a roughly 3% close-to-close move.

The study’s primary endpoint was not met:
del-desiran did not significantly improve video hand-opening time versus placebo. The measure assesses delayed muscle relaxation/stiffness, a hallmark of DM1.

Novartis said there were indications of clinical activity in secondary and exploratory analyses. It plans to review the complete dataset and discuss potential next steps with regulators.

The miss was the company’s second major pipeline disappointment in days. Its cardiovascular drug pelacarsen had just failed to reduce cardiovascular events—including heart attack and stroke—in the Phase III Lp(a)HORIZON trial.

The back-to-back setbacks intensify investor concern about Novartis’s growth pipeline and the strategic rationale for the Avidity acquisition. Analysts had viewed del-desiran as an important potential contributor, with one cited estimate placing possible peak annual sales near $3 billion.