Alnylam Pharmaceuticals, Inc. announced that the U.S. Food and Drug Administration (FDA) approved AMVUTTRA (vutrisiran), an RNAi therapeutic administered via subcutaneous injection once every three months (quarterly) for the treatment of the polyneuropathy of hereditary transthyretin-mediated (hATTR) amyloidosis in adults. hATTR amyloidosis is a rare, inherited, rapidly progressive, and fatal disease with debilitating polyneuropathy manifestations, for which there are few treatment options. The FDA approval is based on positive 9-month results from the HELIOS-A Phase 3 study, where AMVUTTRA significantly improved the signs and symptoms of polyneuropathy, with more than 50 % of patients experiencing halting or reversal of their disease manifestations.

The FDA approval of AMVUTTRA is based on positive 9-month results from HELIOS-A, a global, randomized, open-label, multicenter, Phase 3 study that evaluated the efficacy and safety of AMVUTTRA across a diverse group of patients with hATTR amyloidosis with polyneuropathy. 164 patients with hATTR amyloidosis were randomized 3:1 to receive either 25 mg of vutrisiran (N=122) via subcutaneous injection once every three months or 0.3 mg/kg of patisiran (N=42) via intravenous infusion once every three weeks (reference group) for 18 months. The efficacy of AMVUTTRA was assessed by comparing the AMVUTTRA group in HELIOS-A with the placebo group (n=77) from the landmark APOLLO Phase 3 study of patisiran, a randomized controlled study in a comparable patient population.

AMVUTTRA met the primary endpoint of the study, the change from baseline in the modified Neuropathy Impairment Score + 7 (mNIS+7) at 9 months. Treatment with AMVUTTRA (N=114) resulted in a 2.2 point mean decrease (improvement) in mNIS+7 from baseline as compared to a 14.8 point mean increase (worsening) reported for the external placebo group (N=67), resulting in a 17.0 point mean difference relative to placebo (p<0.0001); by 9 months, 50 % of patients treated with AMVUTTRA experienced improvement in neuropathy impairment relative to baseline. AMVUTTRA also met all secondary endpoints in the study at 9 months, with significant improvement in the Norfolk Quality of Life Questionnaire-Diabetic Neuropathy (Norfolk QoL-DN) score and timed 10-meter walk test (10-MWT), and improvements were observed in exploratory endpoints, including change from baseline in modified body mass index (mBMI), all relative to external placebo.

Efficacy results at 18 months were consistent with 9-month data, with AMVUTTRA achieving statistically significant improvements compared to external placebo for all secondary endpoints including mNIS+7, Norfolk QoL-DN, 10-MWT and mBMI, and non-inferiority in serum TTR reduction relative to the within-study patisiran reference group.