Emily Pearson was just 8 years old when she began to suffer from debilitating reactions to sunlight. Even brief exposure would leave her hands and feet in excruciating pain, likening the sensation to being trapped in a hot oven and pricked with pins. These painful episodes could linger for days, and the mystery of her condition compounded her distress.
Over the next ten years, Pearson’s family sought answers for her troubling symptoms. Despite using sunblock and wearing protective clothing, the situation did not improve. Family trips to their cabin in Minnesota turned into tests of endurance; any slip into sunlight could lead to her hands, feet, and face experiencing severe discomfort.
“The pain was unbearable. I would never wish that on anyone,” expressed Pearson, now residing in Minneapolis.
At the age of 17, a physician at the Mayo Clinic in Rochester, Minnesota, diagnosed her with erythropoietic protoporphyria (EPP), a rare skin disorder that effectively renders individuals allergic to sunlight. While receiving a diagnosis brought some relief, it also meant confronting the reality of her condition without significant options for alleviation.
Running became a source of solace for Pearson. After 12 years of competitive swimming, she transitioned to running half-marathons after high school. To avoid adverse reactions, she had to either dress in layers or run during the early morning or late evening. Nevertheless, the joy derived from running made the challenges worthwhile.
Although Pearson aspired to complete a marathon, she initially felt her condition would prevent her from achieving that goal. During her college years, even a few hours of outdoor fun without protective gear would result in severe pain afterward.
“Every outing—whether it was grocery shopping, getting gas, or simply taking a car ride—required constant consideration of how it might impact my health. The stress was overwhelming,” said Pearson, who is now 25. “It was a significant mental burden with no end in sight.”
In 2025, Pearson volunteered at Sun Escape, a weekend retreat for children with EPP and similar disorders. There, she discovered a clinical trial for a medication called bitopertin and felt compelled to learn more.
“I was cautious, questioning its effectiveness: ‘Does it really work for me?’” Pearson recalled. “The uncertainty was anxiety-inducing.”
Bitopertin targets protoporphyrin IX, a molecule in the skin that becomes activated by sunlight, according to Dr. Sioban Keel, a porphyria specialist at the University of Washington participating in the trial. In individuals with EPP, genetic mutations lead to an excess of protoporphyrin IX, causing painful reactions. The medication, administered as a daily pill, lowers protoporphyrin IX levels, which may help alleviate symptoms.
Pearson joined the trial during its second phase, which involves several hundred participants and focuses on evaluating the drug’s efficacy and potential side effects. After starting bitopertin in July 2025, Pearson attended regular check-ups in Boston. Within weeks, she noticed significant improvements and an increased tolerance for sunlight. Dr. Keel noted that similar positive outcomes were reported by other participants in the trial.
“The difference I’ve observed in my patients has been transformative. Those who couldn’t previously be in the sun are now able to enjoy it,” Dr. Keel remarked.
Data from the clinical trial released by Disc Medicine in April indicated that bitopertin significantly reduced protoporphyrin IX levels and improved sunlight tolerance among EPP patients, with no major safety concerns reported.
Currently, bitopertin is undergoing Phase 3 clinical trials with 183 participants, and results are anticipated in late 2026. The FDA has opted not to expedite its approval process, requesting additional data on its effectiveness, as stated by Disc Medicine. The company is confident that forthcoming Phase 3 results will address the FDA’s criteria.
Pearson continues on the medication through an open-label extension, allowing her to remain on the drug. Her sun tolerance has notably improved, and in October 2025, she fulfilled a long-held dream by completing her first marathon.
“I was outside all day, enjoying every moment,” Pearson shared. “Wearing just shorts and a T-shirt felt liberating. I was proud of my achievement, despite others not knowing my journey.”
This experience motivated Pearson to challenge herself further. She prepared for another marathon in the spring and successfully ran the race in June. In July, she spent a week at her family’s cabin, enjoying the outdoors from sunrise to sunset without any adverse reactions—a stark contrast to her previous experiences. While she occasionally experiences minor reactions after extended outdoor activities, the pain is considerably diminished, and her tolerance has significantly increased.
“It’s hard to articulate the extent of this transformation, as the ability to enjoy the cabin and the outdoors is something I had longed for,” Pearson concluded.
