Abstract 11276: Safety and Tolerability of ALN-AGT, an RNA Interference Therapeutic Targeting Hepatic Angiotensinogen Synthesis, in Hypertensive Patients During Sodium Depletion or Irbesartan Coadministration

Introduction: We have recently reported that ALN-AGT, a subcutaneous (SC) investigational RNA interference therapeutic targeting hepatic angiotensinogen (AGT) synthesis, reduced BP and was generally well tolerated in a single ascending dose study of hypertensive patients. To further assess its safety profile, additional studies have been initiated to test the effects of peak ALN-AGT pharmacology during salt depletion or irbesartan add-on treatment. Methods: As part of a Phase 1 program, hypertensive patients (mean seated SBP of >130 and ≤165 mm Hg after washout of antihypertensive medication) were given a single dose of ALN-AGT 800 mg SC that has been shown to reduce serum AGT by ≥95%. At Day 43 (corresponding to expected peak serum AGT reduction), these ALN-AGT-treated patients were admitted to receive interventions of a 7-day sodium restricted diet (10 mmol sodium day) or a 14-day add-on treatment regimen with the angiotensin receptor blocker irbesartan 300 mg by oral administration daily. Results: In the salt depletion cohort, 12 patients (mean age 56 years, 75% male, 25% black, mean baseline 24-h SBP 141+/- 8 mm Hg) have been dosed 2:1 with ALN-AGT or placebo SC in advance of the sodium restricted diet. In the irbesartan add-on cohort, 10 patients (mean age 55 years, 30% male, 30% black, mean baseline 24-h SBP 147 +/- 8 mm Hg) have received ALN-AGT in advance of irbesartan add-on. The study has completed patient enrollment and interventions with no patient discontinuations due to AEs. The data analysis is ongoing at the time of abstract submission. Conclusions: This ongoing study will provide insight into ALN-AGT tolerability during potential augmented pharmacology, using salt restriction to test ALN-AGT’s effects during reduced extracellular fluid volume and irbesartan coadministration to assess the effects of ALN-AGT’s liver-specific AGT silencing during angiotensin II receptor blockade. Data on tolerability, laboratory safety monitoring, serum AGT reduction, RAAS-related biomarkers, and blood pressure will be presented.