Assessment of home infusion program for treating nonlaryngeal hereditary angioedema attacks

Oral Sebetralstat for On-Demand Treatment of Hereditary Angioedema Attacks

BACKGROUND

Approved on-demand treatments for hereditary angioedema attacks need to be administered parenterally, a route of administration that is associated with delays in treatment or withholding of therapy.

METHODS

In this phase 3, double-blind, three-way crossover trial, we randomly assigned participants at least 12 years of age with type 1 or type 2 hereditary angioedema to take up to two oral doses of sebetralstat (300 mg or 600 mg) or placebo for an angioedema attack. The primary end point, assessed in a time-to-event analysis, was the beginning of symptom relief, defined as a rating of "a little better" on the Patient Global Impression of Change scale (ratings range from "much worse" to "much better") at two or more consecutive time points within 12 hours after the first administration of the trial agent. Key secondary end points, assessed in a time-to-event analysis, were a reduction in attack severity (an improved rating on the Patient Global Impression of Severity [PGI-S] scale, with ratings ranging from "none" to "very severe") at two or more consecutive time points within 12 hours and complete attack resolution (a rating of "none" on the PGI-S scale) within 24 hours.

RESULTS

A total of 136 participants were assigned to one of six trial sequences, with 110 treating 264 attacks. The time to the beginning of symptom relief with the 300-mg dose and the 600-mg dose was faster than with placebo (P<0.001 and P = 0.001 for the two comparisons, respectively), with median times of 1.61 hours (interquartile range, 0.78 to 7.04), 1.79 hours (1.02 to 3.79), and 6.72 hours (1.34 to >12), respectively. The time to reduction in the attack severity with the 300-mg dose and the 600-mg dose was faster than with placebo (P = 0.004 and P = 0.003), with median times of 9.27 hours (interquartile range, 1.53 to >12), 7.75 hours (2.19 to >12), and more than 12 hours (6.23 to >12). The time to complete resolution was faster with the 300-mg and 600-mg doses than with placebo (P = 0.002 and P<0.001). The percentage of attacks with complete resolution within 24 hours was 42.5% with the 300-mg dose, 49.5% with the 600-mg dose, and 27.4% with placebo. Sebetralstat and placebo had similar safety profiles; no serious adverse events related to the trial agents were reported.

CONCLUSIONS

Oral sebetralstat provided faster times to the beginning of symptom relief, reduction in attack severity, and complete attack resolution than placebo. (Funded by KalVista Pharmaceuticals; KONFIDENT ClinicalTrials.gov number, NCT05259917; EudraCT number, 2021-001226-21.).

Management of acute attacks of hereditary angioedema: role of ecallantide

Hereditary angioedema (HAE) is characterized as an episodic swelling disorder with autosomal dominant inheritance. Clinical features include nonpitting edema of external or mucosal body surfaces, and patients often present with swelling of the extremities, abdominal pain, and swelling of the mouth and throat, which can lead to asphyxiation. Patients with HAE classically have no associated urticaria, which is often referred to as nonhistaminergic angioedema. Treatment for HAE involves long-term prophylaxis, short-term prophylaxis, and management of acute attacks. Up until the past few years, acute HAE episodes were predominately treated with supportive measures. Three classes of medications have recently been approved by the US Food and Drug Administration (FDA) for the management of acute HAE attacks. Ecallantide, a recombinant protein that acts as a reversible inhibitor of kallikrein, is currently indicated for acute attacks of HAE in those aged ≥12 years. In two randomized, double-blind, placebo-controlled, multicenter trials, EDEMA3 and EDEMA4, patients treated with 30 mg of ecallantide demonstrated statistically significant improvement in symptoms compared to those on placebo. In addition to its use as treatment for HAE, ecallantide has been used off label in the management of nonhistaminergic angioedema, not due to HAE. Ecallantide has shown promise in the treatment of these other forms; however, data are limited to mainly case reports at this time. Ecallantide is generally a safe and well-tolerated medication; however, based on reports of anaphylaxis, ecallantide does contain a black box warning. Due to the risk of anaphylaxis, ecallantide cannot be self-administered and must be given by a health care professional. Overall, ecallantide is a safe and effective medication for the treatment of acute attacks of HAE.