Long-term management and treatment of acute intermittent porphyria with recurring attacks using pharmacological prophylaxis.

ABSTRACT

BACKGROUND: There is no definitive guidance on whether patients with acute intermittent porphyria (AIP) with recurrent attacks need pharmacological prophylactic treatment. METHODS: The management strategies for patients with frequent (defined as ≥4 annualized attack rate (AAR) and less frequent attacks (<4 AAR), including treatment for acute attacks and duration of prophylaxis (weekly heme arginate 3 mg/kg body weight and/or investigational drug, givosiran), were summarized. The AAR for the following periods were presented the first 2 years after diagnosis, before/after prophylaxis, and the most recent 2 years. RESULTS: A total of 29 patients with AIP were included, 19 (34.5%) had <4 AAR and 10 (65.6%) had ≥4 AAR in the first 2 years after diagnosis. All patients experienced reduced attacks during the treatment course, 23 (79.3%) were attack-free during the most recent 2 years. Among the 9 patients who received prophylaxis (7 heme arginate; 1 givosiran, 1 heme arginate followed by givosiran), 5 (55.6%) were attack-free in the most recent 2-year period and prophylaxis was discontinued because there had been no attacks for >1 year. For patients without prophylaxis (n = 20), 18 (90.0%) were attack-free in the most recent 2-year period and 15 (75.0%) experienced attacks only in the first 2 years after diagnosis. CONCLUSIONS: Prophylaxis could be considered for patients with AIP with ≥4 biochemically confirmed attacks/year after routine treatment of 1-2 years, during which the severity and frequency of attacks should be closely monitored to determine the necessity of pharmacologic prophylaxis. More studies are needed to reach a consensus on the use of pharmacological prophylaxis and treatment of AIP.