Document Type

Article

Publication Date

8-7-2026

Comments

This article is the author's final published version in Future rare diseases, Volume 6, Issue 1, 2026.

The published version is available at https://doi.org/10.1080/23995270.2026.2664391.  The work of Marianne Sweetser is © 2026 Alnylam Pharmaceuticals. Published by Informa UK Limited, trading as Taylor & Francis Group. Kristen Wheeden, Sue Burrell, Susana Monroy, Paolo Ventura, Gang Jia, Manish Thapar and Nicole Castellano hereby waive their right to assert copyright, but not their right to be named as co-authors in the article.

Abstract

Plain Language Summary: What is this summary about? Acute hepatic porphyria, also called AHP, is a family of four rare genetic diseases: Acute intermittent porphyria (AIP) Variegate porphyria (VP) Hereditary coproporphyria (HCP) Delta-aminolevulinic acid dehydratase deficiency porphyria (ADP) These genetic diseases are caused when an enzyme that is involved in the production of a molecule called heme does not work normally. This leads to a buildup of the molecules that produce heme, which is toxic to the body. People with AHP have symptoms such as nausea (feeling sick), pain, tiredness, weakness in arms and legs, and vomiting, and these symptoms can occur either as short-term (acute) attacks (sudden, severe episodes of illness) or as long-term (chronic) symptoms. The ENVISION study analyzed outcomes in people in a clinical trial of givosiran. People with AHP who have had acute attacks were randomly assigned to receive either the study treatment, called givosiran, or placebo (something that looks like and is taken in the same way as the study treatment but does not contain any of the study medicine) for an initial 6-month period. This was followed by a period of 30 months during which everyone in the study took givosiran (the extension period). What was the aim of this study? Researchers examined the outcomes for participants who received givosiran for the whole study (that is, for the initial 6-month period and the extension period) and compared them with the outcomes for participants who received placebo during the initial 6-month period but received givosiran during the extension period. What do the results mean? Data showed that the improvements in people’s symptoms that were observed for participants who received givosiran in the initial 6-month period were maintained throughout the extension period. Importantly, participants who received placebo during the initial 6-month period also had improvements in symptoms during the extension period only, when they were receiving givosiran, and these improvements were similar to those seen for participants who received givosiran from the start of the study. There were no unwanted effects of the medicine reported in this study that had not been seen before in other studies of givosiran. These results suggest that treatment with givosiran provides long-term improvement in symptoms and health-related quality of life for people living with AHP. How to say (download PDF and double click sound icon to play sound)… Delta-aminolevulinic acid: ah-mee-noh-lev-yoo-lin-ik ass-id Heme: he-em Neuropathy: noo-rop-uh-thee Porphobilinogen: por-foh-bih-lin-oh-jen Porphyria: por-fear-ee-a Genetic: Genetics is the study of how traits and characteristics are passed down from biological parents to their children through their genes. Enzyme: A type of protein that helps to break down or to make various substances in a person’s body. Protein: Proteins are large biological molecules that carry out a variety of important functions in a person’s body. Molecule: A group of two or more atoms. One molecule is the smallest unit of a substance that has all of the properties of that substance. Heme: The iron-containing part of certain molecules. The heme part of hemoglobin is the substance inside red blood cells that binds to oxygen in the lungs and carries it to other parts of the body. Placebo: A placebo looks like and is taken in the same way as the study treatment but does not contain any of the study medicine. Researchers use a placebo to help to check if the effects that are seen in the participants receiving a study treatment are actually caused by that treatment, by comparing the results from those who received the study treatment and the results from those who received the placebo. This is an abstract of the Plain Language Summary of Publication article. View the full Plain Language Summary PDF of this article to read the full-text Link to original article here Trial registration:ClinicalTrials.gov identifier: NCT03338816. © 2026 Alnylam Pharmaceuticals. Published by Informa UK Limited, trading as Taylor & Francis Group.

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