Aeglea Submits BLA for Pegzilarginase for Rare Metabolic Disease

If approved, pegzilarginase would be the first treatment for ARG1 deficiency, a rare progressive disease.

Aeglea BioTherapeutics has submitted a biologics license application (BLA) to the FDA for pegzilarginase for the treatment of arginase 1 deficiency (ARG1-D) and has requested priority review.

Pegzilarginase is a recombinant human arginase 1 enzyme that normalizes the elevated levels of the amino acid arginine in patients with ARG1-D, a rare, progressive disease characterized by high levels of arginine. Arginase is one of six enzymes that play a role in the breakdown and removal of nitrogen from the body. The lack of this enzyme results in accumulation of ammonia in the blood and arginine in the blood and cerebrospinal fluid.

People living with ARG1-D experience severe spasticity-related mobility limitations, seizures, developmental delay, intellectual disability, and early mortality.

The submission is based on multiple clinical studies, including the PEACE phase 3 study and its ongoing long-term extension, a phase 1/2 clinical trial and an open-label extension study. The PEACE trial met its primary endpoint with a 76.7% plasma arginine reduction. Additionally, 90.5% of patients treated with pegzilarginase achieved normal plasma arginine levels.

Results from these trials show that pegzilarginase is able to rapidly and sustainably lower arginine levels and showed improvements in mobility. In the PEACE study, most side effects were mild or moderate.

At the patient level analysis of gross motor function, 11 patients (65%) treated with pegzilarginase reached or exceeded response criteria for at least one mobility assessment compared with four patients (44%) receiving placebo. Eight patients (47%) met or exceeded prespecified clinical response criteria for at least two of the mobility outcomes compared to no patients receiving placebo.

The results from the PEACE trial were presented at the Society for Inherited Metabolic Disorders (SIMD) Annual Meeting.

The FDA has granted pegzilarginase multiple regulatory designations, including rare pediatric disease, breakthrough therapy, fast track and orphan drug designations.

European marketing application on track for submission this year, according to the company.