Alnylam Pharmaceuticals reported a robust second-quarter performance driven by its rare heart disease drug Amvuttra, whose sales more than doubled year over year to $492 million. The product's adoption in transthyretin amyloid cardiomyopathy (ATTR-CM) has outpaced expectations, with broad utilization across patient populations and healthcare settings. Nearly 80% of targeted health systems have placed Amvuttra on formulary, and payer access remains favorable. The company raised its revenue outlook, reflecting strong momentum in the rare disease therapeutic market.