Alnylam's Amvuttra Surpasses Expectations, Reshaping ATTR Treatment Landscape

Alnylam Pharmaceuticals has reported exceptional second-quarter sales for its rare disease drug Amvuttra, significantly outperforming Wall Street projections and prompting a substantial increase in the company's financial outlook for 2025. The strong performance of Amvuttra, particularly in its newly approved indication for transthyretin amyloidosis cardiomyopathy (ATTR-CM), has positioned Alnylam as a formidable competitor in the ATTR treatment market.

Amvuttra's Impressive Q2 Performance

Amvuttra, Alnylam's injectable medication for transthyretin amyloidosis (ATTR), generated sales of $492 million between April and June, far exceeding analyst expectations of around $350 million. This figure includes approximately $150 million attributed to patients with ATTR-CM, following the drug's expanded approval by U.S. regulators in March. By the end of the quarter, approximately 1,400 patients were receiving Amvuttra therapy.

In response to these robust results, Alnylam has significantly raised its 2025 financial projections. The company now anticipates net revenue from Amvuttra and its other ATTR drug, Onpattro, to range between $2.18 billion and $2.28 billion, a substantial increase from the previous forecast of $1.6 billion to $1.73 billion. Total net revenues for 2025 are now expected to reach $2.65 billion to $2.8 billion.

Market Dynamics and Competitive Landscape

Amvuttra's success comes amid intense competition in the ATTR treatment market. The drug, priced at $476,000 per year for ATTR-CM, faces competition from Pfizer's oral medication tafamidis, which recorded sales exceeding $5 billion last year, and BridgeBio Pharma's recently launched Attruby.

Despite entering the market later than its competitors, Amvuttra has shown promising uptake. Alnylam CEO Yvonne Greenstreet emphasized that the drug's performance is "not just a flash in the pan," citing broad adoption across newly diagnosed patients and those switching from other treatments. The company's Chief Commercial Officer, Tolga Tanguler, noted that many commercial and Medicare insurers are already approving Amvuttra for newly diagnosed patients without requiring prior treatment with competing drugs.

Future Outlook and Market Expansion

Alnylam executives express confidence in Amvuttra's potential to expand the ATTR-CM treatment market, noting that a significant portion of patients remain untreated. The drug's unique mechanism of action and less frequent dosing schedule (four injections per year) are viewed as potential advantages for patient adherence.

Following the strong Q2 results, some analysts have revised their projections for Amvuttra's peak annual sales. Stifel analyst Paul Matteis, for instance, has increased his estimate from $7 billion to $9 billion.

As Amvuttra's patient base grows, Alnylam plans to gradually lower the drug's net price through rebates and pay-for-performance deals. CFO Jeff Poulton indicated that a "mid-single digit reduction in net price" is expected this year.