Alnylam Strengthens Vutrisiran ATTR-CM Case With Robust Phase III Survival Data

Alnylam Pharmaceuticals has presented detailed findings from its Phase III HELIOS-B study, indicating that its RNA interference therapy, vutrisiran, offers additional survival benefits for transthyretin amyloidosis cardiomyopathy (ATTR-CM) patients. This study is significant as these patients are already being treated with Pfizer’s well-established drug, Vyndamax (tafamidis).

The HELIOS-B study, which spanned 42 months, revealed that combining vutrisiran with Vyndamax reduced the risk of all-cause mortality by 41% compared to a placebo. Additionally, the study highlighted a 22% drop in the composite endpoint of all-cause mortality and recurrent cardiovascular events in this particular subgroup. Despite these promising figures, the outcomes did not achieve statistical significance, with p-values of 0.0983 and 0.2701 respectively.

These findings place Alnylam in a competitive position against Pfizer, whose Vyndamax and its sister drug Vyndaqel (tafamidis meglumine) have dominated the ATTR-CM market since their approval in May 2019. Together, these drugs have generated significant revenue, earning $1.14 billion in the first quarter of 2024 alone.

The stock market responded negatively to Alnylam’s announcement, with the company’s shares dipping by around 16% in premarket trading. This reaction underscores the challenging competitive landscape Alnylam faces in trying to establish vutrisiran as a viable alternative or complement to Pfizer’s offerings.

Vutrisiran, marketed under the name Amvuttra since its approval in June 2022 for polyneuropathy associated with ATTR, is a double-stranded small interfering RNA (siRNA) therapy. It operates by targeting the mRNA of both mutant and wildtype transthyretin molecules, marking them for degradation. This mechanism helps prevent the toxic accumulation of the transthyretin protein, which is central to the pathology of ATTR.

In June 2024, Alnylam had released topline results from the HELIOS-B study, reporting a 28% reduction in the risk of the primary composite endpoint in the overall population. For patients not on any background therapies, vutrisiran reduced the risk of the primary outcome by 33%.

Focusing on all-cause mortality, vutrisiran showed a reduction in risk by 36% and 35% at the 42-month mark in the respective patient groups. These statistics were reiterated in Alnylam’s news release, where Chief Medical Officer Pushkal Garg emphasized that the data suggest vutrisiran could emerge as a new standard of care for ATTR-CM, a disease known for its progressive and ultimately fatal nature with limited treatment options.

Garg also noted the company's commitment to working urgently with regulators to bring this therapy to patients globally. The comprehensive HELIOS-B findings were presented at a Hot Line session during the 2024 Congress of the European Society of Cardiology and were simultaneously published in The New England Journal of Medicine.

In summary, while vutrisiran shows potential in providing additional survival benefits for ATTR-CM patients, Alnylam faces significant hurdles in competing with Pfizer’s well-established therapies. The company's ongoing efforts to present compelling data and gain regulatory approval will be crucial in determining the future landscape of treatment options for ATTR-CM.

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