Long-term study on givosiran shows promising results for acute intermittent porphyria

Givosiran, an RNA interference therapy, has a strong long-term safety profile and significant clinical efficacy for treating adults with acute intermittent porphyria, according to results of a study.

Over a follow-up period of up to 48 months, patients experienced dramatic reductions in the frequency of porphyria attacks and hemin usage, alongside substantial improvements in urinary biomarkers and quality of life.

This research, which includes follow-up data extending up to 48 months—the longest recorded for givosiran—was conducted among participants aged 18 to 65 who had previously completed part C of a related Phase 1 study.

Participants in the study received givosiran for a maximum of 48 months.

Out of the 16 enrolled patients, the most frequently reported adverse effects included abdominal pain, nasopharyngitis, and nausea, each occurring in 50% of participants. Injection-site reactions were also common, with erythema reported in 38% and pruritus in 25%.

Givosiran therapy resulted in a 97% reduction in annual porphyria attack rates and a 96% decrease in hemin usage.
During the last 15 months of the study, all patients experienced no attacks necessitating significant medical intervention and did not require hemin treatment. In addition, median urinary delta-aminolevulinic acid and porphobilinogen levels decreased by 95% and 98%, respectively, alongside significant improvements in quality of life.

Reference
Sardh E, Balwani M, Rees DC, et al. Long-term follow-up of givosiran treatment in patients with acute intermittent porphyria from a phase 1/2, 48-month open-label extension study. Orphanet J Rare Dis. 2024;19(1):365. doi: 10.1186/s13023-024-03284-w. PMID: 39363243; PMCID: PMC11448181.