Firazyr is deemed safe, effective in two Japanese children with HAE

Safety, pharmacological profile consistent with results in adults, other children

Patricia Inácio, PhD avatar

by Patricia Inácio, PhD |

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Firazyr (icatibant injection) rapidly eased acute attack symptoms in two Japanese children with hereditary angioedema (HAE), according to a study led by Takeda Pharmaceuticals, its developer.

The therapy’s safety and pharmacological profile was also consistent with previous observations of adults and other pediatric patients.

Firazyr’s approval in Japan is limited to adults with HAE, but the findings “support the safety and efficacy of icatibant in Japanese pediatric patients,” the researchers wrote in “Safety, efficacy, and pharmacokinetics of icatibant treatment in Japanese pediatric patients with hereditary angioedema: A phase 3, open-label study,” which was published in The Journal of Dermatology. The study was funded by Takeda.

A feature of HAE is sudden swelling attacks that can occur anywhere in the body. They usually occur during childhood or adolescence and become more severe with age.

Firazyr, developed by Shire, which is now part of Takeda Pharmaceuticals, is approved for swelling attack symptoms. It’s administered as an injection under the skin, usually in the abdomen. It can be self-injected as soon as a person has the warning signs of a swelling attack. Generic versions are available in the U.S.

In Europe, the therapy is approved for children ages 2 and older and adults with HAE. In Japan, Firazyr is approved only for adults with HAE. No studies have assessed its effects in pediatric patients, leading Takeda, collaborating with researchers in Japan, to conduct an open-label, Phase 3 trial (NCT04654351) to assess its safety and effectiveness in children and adolescents, ages 2-18, who weighed a minimum of 12 kg (around 26 pounds). The treatment’s pharmacokinetics — its movement into, through, and out of the body — was also assessed.

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Effects of Firazyr in two pediatric patients in Japan

The patients were followed at three hospitals in Japan from January to July 2021. They received a single injection at a dose tailored to their body weight within 12 hours of their first attack symptoms. The therapy was administered in the hospital by a family member with a healthcare professional supervising.

Two more injections, delivered six hours apart, were allowed after two days if the initial dose didn’t ease symptoms or if they got worse. The patients were allowed to use Firazyr to treat up to two additional acute attacks and were monitored for at least eight hours after treatment. A safety assessment was conducted after seven days.

A boy and a girl received Firazyr and completed the study. One received 25 mg after one attack, while the other received 15 mg after three attacks.

Both had injection site reactions, which included mild to moderate skin redness (erythema), mild to moderate swelling, and a mild burning sensation. All resolved within four to 14 hours.

No other side effects were reported. Neither patient developed antibodies against the therapy and there were no clinically meaningful changes in reproductive hormones, vital signs, or other clinical parameters.

For all the attacks, a single injection was enough to lead to a relief of symptoms, according to the patients’ reports. The symptoms began to ease within 18 minutes and one hour, according to both investigator and patient reports. No rescue medications were required. The therapy was rapidly absorbed, reaching a peak in the bloodstream after 36 minutes in both patients.

The therapy’s pharmacological profile was consistent with previous reports of non-Japanese pediatric patients with HAE.

Overall, “the results of this study support the safety and efficacy of icatibant in Japanese pediatric patients with acute HAE attacks,” the researchers wrote. “No new safety signals were identified and administration of a single, weight-adjusted dose of icatibant led to rapid symptom relief.”