Alnylam Completes Enrollment for Phase 3 HELIOS-A Trial Testing Vutrisiran

Alnylam Pharmaceuticals announced that it has completed patient enrollment for its Phase 3 HELIOS-A trial of vutrisiran, which will test the safety and efficacy of the candidate therapy for treating hereditary transthyretin amyloidosis.

HELIOS-A (NCT03759379) enrolled 160 participants from 68 clinical sites across 22 countries worldwide. Topline data is expected by the beginning of 2021.

“We are pleased to have reached another important milestone for our TTR program by completing enrollment of the HELIOS-A study,” Rena Denoncourt, program leader for the vutrisiran clinical program at Alnylam, said in a press release.

“We are committed to developing multiple therapeutic options for this progressive, life-threatening and multisystem disease, and believe that vutrisiran, as a low-dose, once-quarterly, subcutaneously administered investigational therapeutic, can be an attractive option for patients. We look forward to sharing topline results in early 2021,” Denoncourt said.

Hereditary transthyretin amyloidosis or hATTR, also known as familial amyloid polyneuropathy or FAP, is a progressive neurodegenerative disorder caused by mutations in the TTR gene, which provides instructions to make a protein called transthyretin. This protein transports vitamin A (retinol) and a hormone called thyroxine throughout the body. The mutations lead to the production of an abnormal, misfolded protein that tends to clump together and form aggregates known as amyloid deposits in different tissues and organs.

Formerly known as ALN-TTRsc02, Vutrisiran is an RNA-targeted therapy that shuts down the production of the misfolded transthyretin by latching onto and silencing its messenger RNA — the molecule that is used as a template for the production of the protein. Vutrisiran received orphan drug status for the treatment of FAP in both the U.S. and the EU in 2018.

HELIOS-A is a Phase 3, global, randomized, open-label study that has been designed to evaluate the effectiveness and safety of vutrisiran in people with FAP. Participants will be randomly assigned to receive either 25mg of vutrisiran subcutaneously — in under-the-skin injections — once every 12 weeks, or 0.3mg/kg of Onpattro (patisiran), given intravenously, or into the vein, once every three weeks.

Onpattro was the first RNA-targeted therapy to win approval from the U.S. Food and Drug Administration (FDA) for the treatment of FAP. It will be used in the HELIOS-A study for comparison purposes.

For most study goals, the results from patients receiving vutrisiran will be compared with data from participants who were given a placebo in the Phase 3 APOLLO (NCT01960348) trial. That study, completed in 2017, assessed the safety and efficacy of Onpattro in patients with FAP.

The main goals of HELIOS-A include assessing the changes in scores on two tests — the modified Neurologic Impairment Score +7 (mNIS+7) and the Norfolk Quality of Life-Diabetic Neuropathy (Norfolk QoL-DN) — from the start of the study to its nine-month mark.

Secondary goals include changes from the study’s start, or baseline, in a timed 10-meter walk test, body mass index (BMI), and the Rash-built Overall Disability Scale (R-ODS), which is a measure of physical activity and social participation limits.

Investigators also will compare the degree to which transthyretin is reduced in blood samples from those taking vutrisiran with those receiving Onpattro. Other exploratory endpoints include assessing the effects of vutrisiran on specific symptoms of FAP, such as the buildup of amyloid deposits in the heart.

Alnylam also is testing the safety and efficacy of vutrisiran in a separate Phase 3 trial called HELIOS-B (NCT04153149), which is enrolling FAP patients with heart disease (cardiomyopathy). HELIOS-B is still recruiting participants at several sites across the U.S.

Together, both trials will test vutrisiran’s effectiveness across the full spectrum of FAP symptoms.