(Sharecast News) - Shire announced on Friday that, following priority review, the US Food and Drug Administration (FDA) has approved the 'TAKHZYRO' (lanadelumab-flyo) injection for prophylaxis to prevent attacks of hereditary angioedema (HAE) in patients 12 years of age and older.The FTSE 100 company said HAE is a rare, genetic and potentially life-threatening disorder that could result in recurrent attacks of edema (swelling) in various parts of the body."HAE attacks are painful, debilitating, and potentially life threatening," said president of the US Hereditary Angioedema Association T\Anthony J Castaldo."TAKHZYRO provides the HAE community with a new option for the prevention of HAE attacks."We are grateful for the time and effort put forth by the patients and researchers who participated in the clinical trial program that enabled this important addition to the HAE treatment landscape."Shire said TAKHZYRO was the only monoclonal antibody (mAb) that provided targeted inhibition of plasma kallikrein, an enzyme which was "chronically uncontrolled" in people with HAE, to help prevent attacks.The recommended starting dose of TAKHZYRO was 300 mg every two weeks.A dosing interval of 300 mg every four weeks was also effective, the firm said, and could be considered if the patient was well-controlled for more than six months.In the Phase III 'Hereditary Angioedema Long-term Prophylaxis' (HELP) study supporting the FDA approval, TAKHZYRO reduced the number of monthly HAE attacks an average of 87% compared to placebo when administered at 300 mg every two weeks and 73% when given at 300 mg every four weeks.Shire said that in the 26-week clinical study, which included 125 people with HAE, patients taking TAKHZYRO 300 mg every 2 weeks also had 83% fewer moderate to severe attacks, and 87% fewer attacks that needed on-demand treatment.A pre-specified, exploratory analysis showed that 44% of patients receiving TAKHZYRO 300 mg every two weeks had zero attacks compared to placebo for the 26-week treatment period from day 0 to day 182.Additionally, in a post-hoc analysis of the 16-week period from day 70 to day 182, 77% of patients treated with TAKHZYRO in the same dosage arm of the trial were attack-free compared to placebo.TAKHZYRO had a half-life of about two weeks, and was administered as one subcutaneous self-injection every two weeks at the recommended starting dose.In clinical trials, Shire said the majority of patients took one minute or less to complete the injection.The most commonly observed adverse reactions associated with TAKHZYRO were injection site reactions consisting mainly of pain, erythema, and bruising at the injection site; upper respiratory infection; headache; rash; myalgia; dizziness; and diarrhea."With the approval of TAKHZYRO, HAE patients have an innovative treatment that works differently than current options to help prevent attacks," said Shire executive vice-president and head of research and development Andreas Busch."Based on an exploratory and post hoc analysis, after six doses of TAKHZYRO 300 mg every two weeks, 77% or nearly 8 of 10 patients had zero attacks."Busch said the approval reinforced the company's ongoing commitment to developing novel therapies that had a "meaningful impact" on patients."Looking to the future, we continue to work towards our goal of a world in which those living with HAE can aim for zero attacks."The Shire board said FDA approval of TAKHZYRO was based on data from four clinical trials, including the HELP study - the largest prevention study conducted to date in HAE.Of the patients who completed the HELP study who received TAKHZYRO, 97% opted in to an ongoing open-label extension study designed to evaluate the long-term safety and efficacy of TAKHZYRO.Shire added TAKHZYRO to its HAE portfolio with the acquisition of Dyax, which was completed in January 2016 in an all-cash transaction valued at $5.9bn.Under the terms of the acquisition, the non-tradable contingent value right received by Dyax shareholders would now pay $4.00 in cash per Dyax share as a result of the FDA approval of TAKHZYRO, formerly DX-2930.