Alnylam Pharmaceuticals claimed a major success this week, with its RNAi drug Onpattro achieving the primary endpoint in its high-stakes APOLLO-B study for transthyretin amyloid cardiomyopathy.
The phase 3 clinical trial became one of the year’s most closely watched studies in biotech after BridgeBio Pharma’s competing treatment failed in a late-stage trial last December. Because Alnylam’s trial was similarly designed, investors worried it would face the same fate.
Alnylam’s Onpattro is FDA approved to treat polyneuropathy caused by the toxic buildup of misfolded transthyretin protein, a condition called ATTR. Alnylam is seeking to expand Onpattro’s use to treat ATTR cardiomyopathy, or ATTR-CM, which is a leading cause of heart failure.
In the phase 3 study, 360 adults with ATTR-CM were randomized to receive 0.3 mg/kg of Onpattro or placebo intravenously administered every three weeks over 12 months. Here is what researchers found:
- Onpattro takers experienced a significant improvement in a six-minute walk test compared to the placebo group (P=0.016), meeting the trial’s primary goal.
- Patients also reported improved quality of life compared to the placebo group (P=0.04), meeting a secondary goal.
- However, treatment did not lead to a statistically significant difference in a composite assessment, which tracked all-cause mortality and frequency of CV events, as well as six-minute walk test scores.
Alnylam plans to apply for FDA approval of Onpattro in ATTR-CM in late 2022, setting up a potential launch in 2023. If approved, the drug would compete with Pfizer’s blockbuster tafamidis franchise, which raked in $909M last year in the US alone.