Updated: 1-Disc Medicine's late-stage clinical trial succeeds, paving the way for the approval of a "sun allergy" pill

Completely rewritten, with additional analyst commentary and background information

Padmanabhan Ananthan

Reuters, October 19 - Disc Medicine (IRON.O) said on Monday that its experimental pill for a rare disease helped patients stay in the sun longer without pain. Boosted by the news, the company’s shares soared 35% in early trading.

The late-stage clinical trial success paves the way for Disc to resubmit its application for bitopertin. Previously, the U.S. Food and Drug Administration (FDA) rejected(link)the application for the drug earlier this year. Disc plans to submit new data by year-end to support the drug’s potential approval and market launch around mid-2027.

At the time, the FDA pointed to a lack of clear association between the reduction in patients’ protoporphyrin levels and their tolerance to sunlight.

Bitopertin is being developed to treat erythropoietic protoporphyria (EPP), a genetic blood disorder where patients accumulate a substance called protoporphyrin IX (PPIX) in their blood, making them extremely sensitive to sunlight and causing painful skin reactions upon exposure.

“We believe that the breadth and consistency of these key results leave virtually no question as to the likelihood of approval,” said Truist analyst Danielle Brill.

In a clinical trial enrolling 183 patients aged 12 and older, those taking bitopertin saw their PPIX levels drop by 41.4% compared to the placebo group. In the sixth month of treatment, their pain-free time spent outdoors each month increased by 12.2 hours.

The drug also significantly reduced the number of phototoxic reactions, or painful skin responses triggered by light.

“These results represent a major scientific advance in the EPP field... I expect these results will permanently shift the focus of drug development in this area,” CEO John Quisel said on a conference call.

Currently, EPP patients mainly manage their condition by avoiding sunlight or using the CUV.AX implant “Scenesse” made by Clinuvel Pharmaceuticals.

BMO analysts expect bitopertin’s peak sales to reach $1.7 billion and anticipate that patients already being treated under the FDA’s expanded access program will be among the first to adopt it.

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