Encouraging Topline Data has Been Shared From a Phase 3 Study of a Drug for Acute Hepatic Porphyria

Topline results have been shared from a Phase 3 study of the investigational drug givosiran in patients with acute hepatic porphyria. For more detailed information you can view the source press release at Alnylam Pharmaceuticals’ website by clicking here.

About Acute Hepatic Porphyria (AHP)

Porphyria is a group of inherited metabolic disorders caused by the body not producing enough haem. Haem is involved in many processes and is a component of multiple proteins, including haemoglobin, which carries oxygen around the body and makes blood red. Haem is found in many areas but is particularly important to red blood cells, the liver, and bone marrow.

AHP is sub-group of porphyria that is made up of four disorders. The symptoms of AHP can often appear to be different between patients and can be chronic and long term or an episodic attack. Many people with AHP experience excruciating abdominal pain during attacks, and other possible symptoms include weakness, convulsions, and psychological symptoms, among others. Often, because of the rare nature of the disorder and variable symptoms, it can take patients a long time to reach a correct diagnosis. To read more about AHP, click here.

About Givosiran

Givosiran is an experimental drug that is being researched as a potential therapy for AHP. It is an RNAi therapeutic that is designed to reduce levels of ALAS1 in the liver, in order to decrease ALA, PBG, and neurotoxic haem intermediates to near normal levels. Researchers hope that by doing this, the drug will be able to reduce attacks and manage chronic symptoms.  So far, givosiran has received Breakthrough Therapy and Orphan Drug Designations from the FDA, and PRIME and Orphan Drug Designations in the EU for the treatment of AHP.

Research into Givosiran

The safety and effectiveness of givosiran as a treatment for AHP is being studied in a Phase 3 ‘Envision’ clinical trial. It is a double-blind study that is comparing the drug to a placebo over six months of treatment. Alnylam has just shared encouraging topline results. This data comes from 43 patients with AHP who have been part of the trial for at least three months.

It was found that, compared to the placebo, treatment with givosiran was associated with a significant decrease in urinary aminolevulinic acid, which is thought to be a predictor of clinical benefit. Approximately twice as many patients taking givosiran experienced serious adverse events compared to those taking the placebo (22% compared to 10%), and one patient taking givosiran discontinued their treatment after their levels of liver transaminase increased.

The Next Steps

Alnylam has said that they plan to discuss this data was with the FDA, and hope to file a New Drug Application around the end of this year, in support of a potential Accelerated Approval.


Anna Hewitt

Anna Hewitt

Anna is from England and recently finished her undergraduate degree. She has an interest in medicine and enjoys writing. In her spare time she likes to cook, hike, and hang out with cats.

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