FDA Raises Doubts About Alnylam’s Groundbreaking Drug for ATTR-CM Just Before Crucial Adcomm Meeting

Alnylam Pharmaceuticals Faces Roadblock in Expanding Patisiran’s Reach for Treating Heart Conditions

Alnylam Pharmaceuticals’ ambitious bid to extend the potential uses of its groundbreaking drug, patisiran (branded as Onpattro), has hit a significant snag. The company has been striving to gain approval for patisiran as a treatment for cardiomyopathy linked to transthyretin amyloidosis (ATTR-CM), a condition that primarily afflicts the elderly and causes dangerous protein buildup in the heart and tendons.

However, in a prelude to the September 13th meeting of the FDA’s Cardiovascular and Renal Drugs Advisory Committee, the agency has raised doubts about the drug’s effectiveness in this expanded patient population.

The pivotal APOLLO-B study, designed to assess patisiran’s efficacy, yielded positive results for key endpoints, including the distance patients could walk in six minutes and their self-reported health status. Yet, the FDA’s briefing document suggests that the observed effects may be modest and not necessarily noticeable to patients, particularly for those already on background therapy with tafamidis.

This development opens a window of opportunity for Alnylam to challenge Pfizer’s stronghold in the treatment of ATTR-CM with tafamidis, known as Vyndaqel and Vyndamax, which collectively raked in $2.4 billion in revenue last year. The FDA is expected to make a decision on Alnylam’s application by October 8th.

While patisiran earned FDA approval in 2018 for treating hereditary ATTR amyloidosis polyneuropathy, it remains a vital asset for Alnylam, with net revenues reaching $132 million in the company’s second-quarter 2023 financial update, compared to $91 million for Onpattro. Additionally, vutrisiran (Amvuttra), another product by the company, continues to be a strong performer on the market.

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