Shares of Alnylam Pharmaceuticals, Inc. (ALNY) experienced a decline of 8.5% on August 30th following the release of detailed data from the Phase III HELIOS-B trial, which assessed its investigational RNAi therapeutic, Amvuttra (vutrisiran), for an expanded indication. This study aimed to broaden the use of Amvuttra to treat transthyretin-mediated (ATTR) amyloidosis with cardiomyopathy.
The HELIOS-B trial successfully met its primary endpoint, demonstrating a statistically significant reduction in the combined occurrence of all-cause mortality and recurrent cardiovascular events across the entire study population, as well as specifically in those receiving monotherapy. However, a notable finding emerged: while treatment with vutrisiran resulted in a 30% decrease in mortality within the monotherapy group during the double-blind period, this reduction did not reach statistical significance. This lack of significance might have negatively impacted investor sentiment, contributing to the stock’s decline.
Despite this news, it’s important to note that vutrisiran has already gained approval in the United States for the treatment of adult patients with polyneuropathy associated with hereditary ATTR amyloidosis. It has also secured approval in the European Union for the same indication in adult patients exhibiting stage 1 or stage 2 polyneuropathy. Vutrisiran is marketed under the trade name Amvuttra in both the United States and Europe.
Alnylam had previously announced encouraging data from the HELIOS-B trial in June 2024, which evaluated vutrisiran’s efficacy in treating patients with ATTR amyloidosis with cardiomyopathy. This positive news had propelled the company’s shares upward. The Phase III HELIOS-B trial enrolled 655 adult patients diagnosed with ATTR amyloidosis (both hereditary and wild-type) exhibiting cardiomyopathy. These patients were evenly divided into two groups: one receiving vutrisiran 25mg subcutaneously once every three months and the other receiving a placebo, both groups undergoing treatment for up to 36 months.
Alnylam is actively preparing to submit global regulatory applications, including a supplemental new drug application for vutrisiran to the FDA. This submission is slated for later in 2024 and will utilize a Priority Review Voucher. Amvuttra is currently Alnylam’s top revenue generator. In the first half of 2024, this drug achieved sales of $425.4 million, reflecting an 82% year-over-year increase on a reported basis. This encouraging growth is attributed to the initiation of treatment by new patients as well as the shift of patients from ALNY’s Onpattro (patisiran). Onpattro, which is also approved in the United States and European Union for treating ATTR amyloidosis in adults, is a product from Alnylam.
Alnylam believes that, if approved for this new indication, vutrisiran has the potential to become the standard treatment for ATTR amyloidosis with cardiomyopathy. This prospect is anticipated to further boost sales and expand the eligible patient population for the drug in subsequent quarters.