Fazirsiran for Adults with Alpha-1 Antitrypsin Deficiency Liver Disease: A Phase 2 Placebo Controlled Trial (SEQUOIA)

BACKGROUND & AIMS Homozygous ZZ alpha-1 antitrypsin (AAT) deficiency produces mutant AAT (Z-AAT) proteins in hepatocytes, leading to progressive liver fibrosis. We evaluated the safety and efficacy of an investigational RNA interference therapeutic, fazirsiran, that degrades Z-AAT mRNA, reducing deleterious protein synthesis. METHODS This ongoing, phase 2 study randomized 40 patients to subcutaneous placebo or fazirsiran 25/100/200 mg. The primary endpoint was percentage change in serum Z-AAT concentration from baseline to Week 16. Patients with fibrosis on baseline liver biopsy received treatment on Day 1, Week 4, and then every 12 weeks, and had a second liver biopsy at or after Weeks 48, 72, or 96. Patients without fibrosis received two doses on Day 1 and Week 4. RESULTS At Week 16, least-squares mean percent declines in serum Z-AAT concentration were −61%, −83% and −94% with fazirsiran 25/100/200 mg, respectively, versus placebo (all P< .0001). Efficacy was sustained through Week 52. At post-dose liver biopsy, fazirsiran reduced median liver Z-AAT concentration by 93% compared with an increase of 26% with placebo. All fazirsiran-treated patients had histological reduction from baseline in hepatic globule burden. Portal inflammation improved in 5/12 and 0/8 patients with baseline score >0 in the fazirsiran and placebo groups, respectively. Histological METAVIR score improved by >1 point in 7/14 and 3/8 patients with fibrosis >F0 at baseline in the fazirsiran and placebo groups, respectively. No adverse events led to discontinuation and pulmonary function tests remained stable. CONCLUSIONS Fazirsiran reduced serum and liver concentrations of Z-AAT in a dose dependent manner and reduced hepatic globule burden (NCT03945292).