The United States Food and Drug Administration (FDA) has approved United States-based Alnylam Pharmaceuticals Inc's Oxlumo (lumasiran) as the first treatment for primary hyperoxaluria type 1 (PH1), a rare genetic disorder, it was reported on Monday.

The product has received approval based on the work of experts and community members coordinated by the Oxalosis & Hyperoxaluria Foundation and the Kidney Health Initiative. It works to decrease oxalate production and was assessed in two studies in patients with PH1: a randomised, placebo-controlled trial in patients six years and older and an open-label study in patients younger than six years.

During the first study, 26 patients received a monthly injection of Oxlumo followed by a maintenance dose every three months; 13 patients received placebo injections. The primary endpoint was the amount of oxalate measured in the urine over 24 hours. In the Oxlumo group, patients had, on average, a 65% decrease of oxalate in the urine, compared to an average 12% reduction in the placebo group. By the sixth month of the study, 52% of patients treated with the product reached a normal 24-hour urinary oxalate level; no patients treated with the placebo did.

During the second study, 16 patients younger than six years all received the product. Using another measure of oxalate in the urine, the study showed, on average, a 71% decrease in urinary oxalate by the sixth month of the study. Oxlumo received orphan drug designation, which provides incentives to assist and encourage drug development for rare diseases.

The application was also granted breakthrough therapy designation. In addition, the manufacturer received a rare paediatric disease priority review voucher. The FDA's rare paediatric disease priority review voucher program is intended to encourage development of new drugs and biologics to prevent and treat rare diseases in children.