Shire plc has announced that the United States Food and Drug Administration (FDA) has granted Fast Track designation for recombinant ADAMTS13 (SHP655 - historically known as BAX930) for treatment of acute episodes of hereditary thrombotic thrombocytopenic purpura (hTTP) in patients with a constitutional deficiency of the von Willebrand factor-cleaving (VWF) protease ADAMTS13. Hereditary thrombotic thrombocytopenic purpura is a life-threatening congenital disease caused by a deficiency in the enzyme ADAMTS13 which can cause clotting in the microvasculature with associated organ morbidities.

"As the leader in rare disease, Shire is committed to providing an innovative pipeline of world class therapeutics to the patients that need them most,” said Philip J. Vickers, Ph.D., Head of R&D, Shire. “Today’s confirmation from FDA that SHP655 for hereditary thrombotic thrombocytopenic purpura has been granted Fast Track designation reaffirms the significant unmet need that exists for this patient population and provides hope of reducing morbidity in patients with hTTP.”

FDA’s Fast Track designation is supported by preclinical data and a Phase 1 study. The FDA’s Fast Track process is designed to facilitate the development, and expedite the review of drugs to treat serious conditions and fill an unmet medical need. However, it does not guarantee that the FDA will ultimately approve SHP655 or the timing of any such approval.

Shire will initiate its Phase 3 trial with SHP655 as a randomized, open-label, 2-period crossover study with a single arm continuation to evaluate the safety and efficacy of SHP655 in the treatment and prevention of acute TTP events in patients with severe hereditary ADAMTS13 deficiency. This global study will be conducted in the U.S., Europe, and Japan.

The phase 1 data included results from 15 patients with severe hTTP who completed the multicenter study. Each patient received a single dose of SHP655 in one of three dosing cohorts. The activity PK parameters, including terminal half-life, were comparable to those estimated from fresh frozen plasma (FFP) studies and demonstrated dose proportionality with respect to Cmax and AUC.4 No serious adverse events were reported. In the highest dosing cohort, three subjects reported three possibly related adverse events, nausea, flatulence and decreased VWF antigen and VWF activity; all of these reported adverse events resolved without medication. Immunogenicity tests performed at screening, pre-dose and upon study completion, were negative in all subjects.