Alnylam Stock Surges After Rival's Heart Drug Fails Late-Stage Trial

Alnylam Pharmaceuticals (ALNY) shares surged more than 11% in morning trading after a competing drug developed by Ionis Pharmaceuticals and AstraZeneca failed in a late-stage clinical trial. The setback for the rival therapy is seen as a significant competitive win for Alnylam's leading treatment in the rare disease space.

Key Trial Disappoints

Ionis and AstraZeneca announced that their drug, eplontersen (marketed as Wainua), did not meet its primary efficacy endpoint in the Phase 3 CARDIO-TTRansform trial. The study aimed to show that the drug could reduce the composite of cardiovascular mortality and recurrent cardiovascular events in patients with transthyretin-mediated amyloid cardiomyopathy (ATTR-CM).

The outcome was described as a major surprise, as Wall Street had widely anticipated the trial's success. Eplontersen was expected to become a strong competitor to Alnylam's AMVUTTRA (vutrisiran) in what analysts estimate could be a $15 billion-plus market.

Competitive Landscape Shifts

The trial's failure significantly reduces the near-term competitive pressure on Alnylam's AMVUTTRA. Analysts at Stifel, who maintained a Buy rating on Alnylam, noted the result reinforces the company's strong standing in the ATTR-CM market and removes a key valuation driver for Ionis.

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Notably, eplontersen failed to show a statistically significant benefit in the majority of trial patients who were already receiving TTR stabilizer therapy. This detail underscores the challenge of improving upon the current standard of care, where Alnylam's RNAi-based treatment is a leader.

Market Reaction

The news triggered a clear rotation among investors in the sector. In addition to Alnylam's 11.4% gain, shares of peer BridgeBio Pharma also rallied on the news.

Conversely, the companies behind the failed trial saw their stocks decline:

• Ionis Pharmaceuticals (IONS) shares plunged.
• AstraZeneca's (AZN) U.S.-listed shares fell meaningfully.