US FDA declines to approve Disc Medicine's rare disease drug

Feb 13 (Reuters) - Disc Medicine IRON.O said on Friday the U.S. Food and Drug Administration has declined to approve its drug to treat a rare genetic disorder, sending its shares down more than 20% by the close.

The company was seeking approval for its experimental drug bitopertin as a treatment for patients with erythropoietic protoporphyria, a blood disorder caused by a deficiency of the ferrochelatase enzyme.

The deficiency causes a substance called protoporphyrin to build up in the blood, leading to extreme sensitivity to sunlight and some artificial light, which can cause painful skin reactions.

Disc said the agency concluded the two mid-stage trials did not show a clear link between the reduction in patients' protoporphyrin levels and their tolerance to sunlight.

The drug was being reviewed under the FDA's national priority voucher program, which fast-tracks the review process to one to two months from the typical 10-12 months.

Reuters had exclusively reported last month that FDA reviewers pushed back bitopertin's review by two weeks on concerns about trial data and its risk for abuse.

The delay was due to the agency's concerns over whether pain-free time in the sun - a secondary trial goal - was a statistically solid measure of efficacy, or if other biomarker data could justify approval, Reuters had reported.

The company on Friday said the issue raised by the regulator is "readily addressable" as it expects results from its ongoing late-stage study in the fourth quarter of this year.

"While our efforts at utilizing expedited pathways to get bitopertin to patients quickly have not come to fruition, we are continuing to pursue all avenues in support of FDA approval," said CEO John Quisel.

Disc plans to respond to the FDA's rejection letter once the late-stage study is completed and expects an updated FDA decision by mid-2027.