Clinical Trial Offers Relief for Woman with Rare Sun Allergy

For Emily Pearson, a diagnosis of erythropoietic protoporphyria (EPP) at age 17 brought relief but also the grim reality of a condition with no effective treatment. The rare skin disorder causes extreme sensitivity to sunlight, leaving her hands, feet, and face in severe pain after even brief exposure. Now 25, Pearson says the chronic discomfort was “insufferable” and fundamentally limited her life.

Since childhood, Pearson had to navigate daily activities with extreme caution. Simple errands like grocery shopping or driving required careful planning to avoid sun exposure, which could trigger days of pain. She adapted her running hobby by layering up or exercising only at sunrise and sunset. Despite these challenges, she dreamed of completing a marathon but believed her condition made the feat impossible.

The turning point came in 2025 when Pearson learned about a clinical trial for bitopertin, a drug developed by Disc Medicine. Initially skeptical, she enrolled in the Phase 2 trial and began taking the once-daily pill in July 2025. The results were immediate and dramatic. Within weeks, her tolerance to sunlight increased significantly.

Dr. Sioban Keel, a porphyria expert at the University of Washington involved in the trial, described the medication as a “game changer.” Bitopertin works by targeting protoporphyrin IX, a molecule that accumulates in patients with EPP and triggers painful reactions when activated by sunlight. Published data from April indicated the drug significantly reduced protoporphyrin-IX levels and improved sunlight tolerance with no notable safety concerns.

The impact on Pearson’s life has been profound. In October 2025, she completed her first marathon, running outdoors in shorts and a T-shirt without protective gear. She followed this with another marathon in June and spent an entire week at her family’s Minnesota cabin in July, enjoying the sun from sunrise to sunset without the severe reactions that previously plagued her.

While bitopertin is now in Phase 3 trials with 183 patients enrolled, the FDA has declined expedited approval, requesting additional data on long-term patient impact. Disc Medicine anticipates the Phase 3 results in late 2026 will satisfy these requirements.

Pearson continues to participate in an open-label extension of the trial. Her outlook has shifted from anxiety to optimism; she plans to run another marathon in June 2027 and considers attempting a triathlon, combining her passion for running with her background as a competitive swimmer.

“My life has literally changed so much,” Pearson said. “I’m 20 times happier. I’m more energetic. I’m able to feel free and live without all the worry and anxiety that I was before.”