Disc Medicine Stock Soars 31% After Bitopertin Hits All Goals in Pivotal Trial for Rare Sunlight Disorder

NEW YORK — Shares of Disc Medicine jumped more than 30% on Monday after the biotechnology company said its experimental drug bitopertin met all of its main and secondary goals in a late-stage trial for a rare genetic disorder that causes severe sensitivity to sunlight.

Disc Medicine shares were up $17.65, or 31.04%, at $74.49 in morning trading on the Nasdaq. Nearly 3 million shares changed hands, about six times the stock's average daily volume. The company has a market value of about $2.85 billion.

The stock had closed Friday at $56.84. It surged as much as 50% to 60% in premarket trading before giving back some of those gains after the open.

Trial results

The Watertown, Massachusetts-based company said the Phase 3 APOLLO trial of bitopertin in patients with erythropoietic protoporphyria, or EPP, achieved statistical significance on both of its co-primary endpoints and on all secondary endpoints compared with a placebo.

The trial enrolled 183 adults and adolescents aged 12 and older with EPP or a related condition, X-linked protoporphyria, across the United States, Canada, Europe and Australia. Patients were randomly assigned to receive either 60 milligrams of bitopertin or a placebo once daily for six months.

Patients taking bitopertin saw a 41.4% reduction in whole-blood levels of metal-free protoporphyrin IX, the toxic compound that builds up in the body and causes symptoms of the disease, according to the company.

Patients also experienced an increase of 12.2 hours in their average monthly total time spent in light without pain by the sixth month, and the drug significantly reduced phototoxic reactions over the treatment period.

Safety profile

Disc Medicine said bitopertin was generally well tolerated. The most common side effect was dizziness, reported in 50% of patients receiving the drug. Those cases were mild or moderate and generally temporary, and no adverse events above Grade 3 were reported, according to the company.

What is EPP?

Erythropoietic protoporphyria is a rare inherited disorder in which a buildup of protoporphyrin in the blood and skin causes intense, burning pain after even brief exposure to sunlight. Patients often must avoid the outdoors and severely limit their daily activities.

Treatment options are limited, and patients have long sought therapies that address the underlying cause of the disease.

Path back to the FDA

The results are a major step in the company's effort to win approval after a setback earlier this year. In February, the U.S. Food and Drug Administration issued a complete response letter for bitopertin, declining to approve it based on earlier data and requesting additional evidence.

Disc Medicine later met with the FDA and said the agency agreed that a successful APOLLO trial could serve as the basis for responding to the letter and potentially support a traditional approval.

The company said it plans to resubmit its application to the FDA by the end of 2026.

Volatile year for shareholders

Despite Monday's gain, Disc Medicine shares remain down about 35% over the past year, reflecting the impact of the FDA rejection.

The company also offers bitopertin to eligible patients through an expanded access program while it seeks approval, and is developing other treatments for blood disorders, including anemia linked to myelofibrosis.

Investors will watch for the company's resubmission to the FDA and for detailed trial results to be presented at an upcoming medical meeting. A positive trial does not guarantee approval, and the FDA's review is expected to take several months after resubmission.