for people ages 12 years and up (full criteria)
at San Francisco, California and other locations
study started
estimated completion



The purpose of this study is to evaluate the effect of subcutaneous givosiran (ALN-AS1), compared to placebo, on the rate of porphyria attacks in patients with Acute Hepatic Porphyrias (AHP).

Official Title

ENVISION: A Phase 3 Randomized, Double-blind, Placebo-Controlled Multicenter Study With an Open-label Extension to Evaluate the Efficacy and Safety of Givosiran in Patients With Acute Hepatic Porphyrias


Acute Hepatic Porphyria Acute Intermittent Porphyria Porphyria, Acute Intermittent Acute Porphyria Hereditary Coproporphyria (HCP) Variegate Porphyria (VP) ALA Dehydratase Deficient Porphyria (ADP) Acute Intermittent Porphyria (AIP) Acute Hepatic Porphyria (AHP) ALA dehydratase deficient porphyria (ADP) (ALAD) RNAi therapeutic Porphyria Porphyrias, Hepatic Coproporphyria, Hereditary Porphyria, Variegate Porphyria, Erythropoietic Porphyrias Givosiran Givosiran/Givosiran 2.5 mg/kg


You can join if…

Open to people ages 12 years and up

  • ≥ 12 years of age
  • Diagnosed with Acute Hepatic Porphyria (Acute Intermittent Porphyria, Hereditary Corproporhyria, Variegate Porphyria, aminolevulinic acid (ALA) dehydratase deficient porphyria)
  • Elevated urinary or plasma porphobilinogen (PBG) or ALA values within the past year,
  • Have active disease, with at least 2 documented porphyria attacks within the last 6 months
  • Willing to discontinue or not initiate the use of prophylactic hemin throughout the study.
  • Women of child bearing potential must have a negative serum pregnancy test, not be nursing, and use acceptable contraception

You CAN'T join if...

  • Clinically significant abnormal laboratory results
  • Anticipated liver transplantation
  • History of multiple drug allergies or intolerance to subcutaneous injections
  • Active HIV, hepatitis C virus, or hepatitis B virus infection(s)
  • History of recurrent pancreatitis


  • Clinical Trial Site
    San Francisco California 94143 United States
  • Clinical Trial Site
    Salt Lake City Utah 84112 United States


in progress, not accepting new patients
Start Date
Completion Date
Alnylam Pharmaceuticals
Phase 3
Study Type
Last Updated