Alnylam's Amvuttra Dominates Q2 Earnings, Reshaping ATTR-CM Market

Alnylam Pharmaceuticals has reported a remarkable second-quarter performance, largely driven by the success of its siRNA therapy Amvuttra in the ATTR-cardiomyopathy (ATTR-CM) market. The company's revenues soared past analyst expectations, prompting a significant upward revision of its full-year 2025 guidance.

Amvuttra's Stellar Performance

In its first commercial quarter for ATTR-CM, Amvuttra reached approximately 1,400 patients and generated over $490 million in sales. This represents a 112% increase from the same period last year, combining revenues from both its polyneuropathy of hereditary transthyretin-mediated amyloidosis (ATTR) indication and the newly approved ATTR-CM indication.

Alnylam's total Q2 revenues hit $773.7 million, marking a 17% year-on-year growth and substantially beating the consensus forecast of $651 million. This impressive performance has led the company to raise its full-year sales guidance from $2.05-$2.25 billion to $2.65-$2.8 billion, a 27% increase.

Market Implications and Competitive Landscape

Amvuttra's strong launch has significant implications for the ATTR-CM market, where it faces competition from established players. Pfizer's transthyretin stabilizer tafamidis, marketed as Vyndaqel and Vyndamax, has been a dominant force since its 2019 approval. In 2024, Pfizer reported $5.45 billion in sales for its tafamidis products, representing a 60% year-on-year growth.

Despite Alnylam's impressive entry, Pfizer remains confident in its market position. CEO Albert Bourla has stated that the company expects to maintain a "lion's market share" for new ATTR-CM prescriptions, citing Pfizer's extensive network and deep understanding of physician prescription patterns.

Another competitor in the ATTR-CM space is BridgeBio's Attruby, which received approval in November 2024. As of April 25, 2025, more than 2,000 unique patients had been treated with Attruby, resulting in $36.7 million in sales during its first commercial quarter.

The rapid uptake of Amvuttra in the ATTR-CM market suggests a potential shift in treatment paradigms, with analysts at Stifel noting that the drug's performance "clearly aligns with the bull case and makes us more optimistic on peak sales potential." As competition intensifies, the ATTR-CM market is likely to see further innovation and potentially improved patient outcomes.