Product information and disease description Product description Product information

Product comparison

9 evidence topics · 11 sources

Summary: products approved or in late-stage development for these disorders

Afamelanotide is the only approved product. It shares dersimelagon's target, the melanocortin 1 receptor, but is given as a 16 mg fixed-dose subcutaneous implant every 2 months by a trained and accredited implanter, is indicated for adults with erythropoietic protoporphyria only, and has no established safety or effectiveness in patients under 18 years. Two investigational products act on protoporphyrin IX rather than on pigmentation. Bitopertin, a glycine transporter 1 inhibitor taken orally, lowers whole-blood metal-free protoporphyrin IX; its application for accelerated approval received a complete response letter in February 2026 after the Food and Drug Administration concluded that the phase 2 trials did not show an association between the change in protoporphyrin IX and sunlight-exposure endpoints, and its phase 3 APOLLO trial is ongoing. PORT-77, an oral ABCG2 inhibitor, reduced plasma protoporphyrin IX in a phase 2a study and entered phase 2b/3 in September 2026. No head-to-head trial, network meta-analysis, or indirect treatment comparison exists across these products, and each program uses a different primary endpoint, so relative efficacy cannot be estimated from the published evidence.

Mechanistic distinction between symptomatic and protoporphyrin-lowering products

“While afamelanotide and dersimelagon are symptomatic treatments, bitopertin and cimetidine aim to decrease blood PPIX concentration which makes them potentially causative treatment options” (opens the source at this quote in a new tab)
“Our search in the clinical trials registries retrieved 29 trials that included patients with EPP. From these, we identified 16 clinical trials evaluating afamelanotide and three new pharmacotherapies, i.e., dersimelagon, bitopertin and cimetidine. Safety and efficacy of all new pharmacotherapies are currently being investigated against placebo-control groups or against baseline. Because of differences in the outcome measures and included patient populations, the results of the trials cannot be directly compared.” (opens the source at this quote in a new tab)

Regulatory status of bitopertin

“We initiated the APOLLO trial in May 2025 and in September 2025 we submitted a New Drug Application, or NDA, for accelerated approval of bitopertin in EPP and XLP in the United States based on our existing data. In October 2025, we were awarded a Commissioner's National Priority Voucher, or CNPV, from the FDA for bitopertin in EPP and XLP.” (opens the source at this quote in a new tab)
“The FDA accepted our NDA for review in November 2025 and in February 2026 issued a complete response letter, or CRL.” (opens the source at this quote in a new tab)

Basis for the complete response letter issued for bitopertin

“On the first point, the FDA agreed that AURORA and BEACON provided sufficient evidence that bitopertin significantly lowers whole blood metal-free PPIX. On the second, based on review of AURORA and BEACON results, the FDA concluded that the trials did not show evidence of association between percent change in PPIX and sunlight exposure-based endpoints, as measured in the trials, despite the strong mechanistic and biological plausibility supporting the use of the PPIX biomarker in protoporphyria. The FDA indicated results of the APOLLO study could serve as evidence to support traditional approval.” (opens the source at this quote in a new tab)

Phase 3 trial of bitopertin

“The goal of this clinical trial is to learn if bitopertin works and is safe to treat EPP or XLP in participants 12 years or older.” (opens the source at this quote in a new tab)
“Average monthly total time in sunlight on days without pain from a phototoxic reaction between 10:00 to 18:00 (10:00 AM to 6:00 PM) after 6 months (24 weeks) of treatment” (opens the source at this quote in a new tab)
“Percent change from baseline in whole-blood metal-free PPIX levels at 6 months” (opens the source at this quote in a new tab)

Phase 2 results for bitopertin

“Patients received bitopertin 20 mg (n = 26), 60 mg (n = 25), or placebo (n = 24). At day 121, the percentage change from baseline in whole-blood metal-free protoporphyrin-IX versus placebo was -29.6% (P = .004) with bitopertin 20 mg and -49.8% (P < .001) with bitopertin 60 mg. Bitopertin was associated with a reduced incidence of phototoxic reactions.” (opens the source at this quote in a new tab)

Development status of PORT-77

“PORT-77 is an oral, small molecule ABCG2 inhibitor currently in Phase 2 development for EPP and XLP. PORT-77 is designed to modify efflux of PPIX from the red blood cell to the plasma and from hepatocytes to the biliary tract, representing a potentially disease-modifying, leading treatment that addresses the root cause of EPP and XLP.” (opens the source at this quote in a new tab)
“PORT-77 resulted in rapid, dose-dependent reductions in plasma PPIX with a mean decrease of 79% for participants receiving 300 mg BID and 63% for those receiving 180 mg QD.” (opens the source at this quote in a new tab)

Expedited designations granted for PORT-77

“the United States (U.S.) Food and Drug Administration (FDA) has granted Orphan Drug Designation and Fast Track Designation to its affiliate, Portal Therapeutics, for PORT-77, an investigational oral, small molecule ABCG2 inhibitor, for the treatment of EPP and XLP.” (opens the source at this quote in a new tab)

Absence of comparative evidence

“The currently available trial data on dersimelagon and bitopertin suggests treatment effects in EPP as compared to placebo control groups. However, safety and efficacy of dersimelagon and bitopertin need to be further characterized. Moreover, to ensure benefit for patients and access to therapy after regulatory approval, it also would be important to generate data on the relative safety and efficacy as compared to afamelanotide.” (opens the source at this quote in a new tab)