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Alnylam Pharmaceuticals Inc. saw its stock price sink to its lowest point in the last year after the Cambridge company announced changes to a Phase 3 clinical trial that's already underway.
Alnylam (Nasdaq: ALNY) disclosed there would be a delay and change in study design in a trial designed to evaluate its drug vutrisiran in patients with ATTR amyloidosis with cardiomyopathy, a potentially fatal disease of the heart muscle. Alnylam shared the changes during its fourth-quarter earnings call on Thursday.
While Pushkal Garg, Alnylam’s chief medical officer, called the late-stage study changes “enhancements” during the company’s earnings call, investors were still concerned.
The news sent Alnylam’s stock down about 10% since Wednesday's close, resulting in a loss of nearly $2 billion in market capitalization.
Alnylam’s stock price was around $148 each as of Friday afternoon, giving the company a market capitalization of $18.6 billion.
Changes to the Phase 3 trial
Garg said Alnylam is increasing the follow-up period for the study by three months, from 30 to 33 months, which means topline data will now come in late June or early July.
“This is an important change as these three additional months of observation constitute a short, but meaningful prolongation during the critical late part of the study, which is when we expect to see the greatest number of outcome events happening in the placebo arm,” Garg said during the earnings call.
Alnylam is also changing the methodology used to analyze the primary endpoint in this study. The previous primary endpoint looked at whether vutrisiran reduced the risk of death or cardiovascular events in the overall study population compared to placebo. Garg said Alnylam now plans to analyze data from the overall study population and a subgroup of patients not already on tafamidis, Pfizer’s approved drug for ATTR-CM.
“We are maintaining the analysis in the overall population, which has the largest sample size and an opportunity to show a broad effect across the full patient spectrum. We are confident that there is a combo effect as demonstrated by the fact that the overall population remains in the primary end point,” Garg said.
Vutrisiran, which is sold under the brand name Amvuttra, has already been approved as a medicine for polyneuropathy caused by hATTR amyloidosis, a nervous system condition.
Alnylam’s predecessor to vutrisiran, a drug called patisiran, was rejected by the FDA last October as a treatment for cardiomyopathy of ATTR amyloidosis. The FDA rejected patisiran citing a lack of “clinical meaningfulness.”
Alnylam is headquartered in Cambridge and had about 2,100 full-time employees at the end of 2023, according to its most recent annual report filed with the U.S. Securities and Exchange Commission this week. Around 1,650 of its employees are based in the U.S.
The company is focused on developing drugs based on ribonucleic acid interference, or RNAi. Drugs based on RNAi work by stopping the production of the genes that cause specific diseases. Alnylam is developing drugs in four areas: genetic medicines, cardio-metabolic diseases, infectious diseases, and central nervous system and ocular diseases.
