Dersimelagon
An investigational treatment for Erythropoietic Protoporphyria.
The same compound appears under different names depending on the context. Here is how to identify Dersimelagon wherever you encounter it, plus the key facts at a glance.
- Generic name
- Dersimelagon
- Development code
- MT-7117
- Drug class
- Oral melanocortin 1 receptor agonist
- Manufacturer
- LEO Pharma (acquired from Tanabe Pharma, September 2026)
- How it's taken
- Oral tablet once daily (200 mg in the Phase 3 trial)
A once-daily pill from LEO Pharma, developed by Tanabe Pharma, that works through the same skin-pigment receptor as the Scenesse implant. Its Phase 3 INSPIRE trial met its goal in adults and adolescents with EPP or XLP, and the FDA is reviewing it under priority review with a decision expected by the end of February 2027.
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Where Dersimelagon fits
If approved it would be the first oral treatment for EPP and XLP and the first treatment for adolescents, since Scenesse covers adults only. It does not lower protoporphyrin, so, like Scenesse, it addresses light tolerance rather than the liver side of the disease. No trial has compared it with Scenesse.
How Dersimelagon works
Dersimelagon is a small molecule taken by mouth that binds the melanocortin 1 receptor on the skin's pigment cells, the same receptor that the Scenesse implant activates with a peptide[3]. Activating MC1R increases melanin, which absorbs light before it reaches the protoporphyrin in the skin, so the tingling and burning that warn of a phototoxic reaction begin later[3][2].
Tanabe describes it as selective for MC1R over the related melanocortin receptors, and the expected on-target effects, darker skin and darker or new moles, showed up in the trial[3].
Mechanism: Oral, non-peptide small molecule that selectively activates the melanocortin 1 receptor (MC1R) on pigment cells, increasing melanin and the skin's tolerance of light
Side effects and safety
Tanabe reported that dersimelagon was generally well tolerated in INSPIRE, with a safety profile consistent with its mechanism[3]. The most common adverse events that occurred more often than with placebo were melanocytic nevi (benign moles), headache, nausea, diarrhea and skin hyperpigmentation[3].
Percentages by group, serious adverse events and discontinuations have not been released in a company statement, and there is no FDA label yet; the open-label extension study's primary measures include adverse events, physical examination findings and the appearance of moles[5]. Tanabe said the drug had been studied in 410 participants with EPP or XLP as of March 2026[3].
This is not a complete list of side effects. Talk to your doctor or pharmacist about what to expect and when to seek medical attention.
Taking Dersimelagon
In INSPIRE, participants took dersimelagon 200 mg or placebo by mouth once a day for 16 weeks, followed by 36 weeks of open-label active treatment[3]. The dose, strength and any food instructions for a marketed product will come with the FDA label if it is approved. Participants in the long-term extension study (NCT05005975) continue to receive the drug[5].
How EPP and XLP treatments compare
Scenesse is the only FDA-approved treatment for erythropoietic protoporphyria, and it is approved for adults. Behind it are 3 oral drugs at different stages: dersimelagon is under FDA review, bitopertin received a complete response letter and finished its Phase 3 trial, and PORT-77 is recruiting for a Phase 2b/3 trial. Scenesse and dersimelagon work on skin pigment; bitopertin and PORT-77 try to lower protoporphyrin itself. None has been compared head to head.
Erythropoietic Protoporphyria has 1 FDA-approved treatment: Scenesse (afamelanotide, approved 2019). Also compared, not FDA-approved for erythropoietic protoporphyria: Dersimelagon (MT-7117) (dersimelagon, Under FDA priority review, decision by end of February 2027); Bitopertin (DISC-1459) (bitopertin, Complete response letter February 13, 2026; Phase 3 APOLLO topline due October 19, 2026); PORT-77 (PORT-77, Phase 2b/3 recruiting; not yet reviewed by the FDA). Scenesse is typically used as adults with a history of phototoxic reactions from epp.
| Drug | How it works | How it’s given | How often | Where you get it | Who it is for | FDA status |
|---|---|---|---|---|---|---|
Scenesse afamelanotide | MC1R agonist: a peptide that switches on eumelanin production so the skin absorbs light before it reaches protoporphyrin | Dissolving 16 mg implant placed under the skin above the hip | Every 2 months | Clinuvel-accredited EPP Specialty Center (about 120 in North America) | Adults with a history of phototoxic reactions from EPP | 2019 |
Dersimelagon (MT-7117) dersimelagon You are here | MC1R agonist: a small molecule with the same pigment target as Scenesse | Oral tablet | Once daily (200 mg in Phase 3) | Home, if approved | Studied in people aged 12 to under 75 with EPP or XLP | Under FDA priority review, decision by end of February 2027 |
Bitopertin (DISC-1459) bitopertin | GlyT1 inhibitor: slows heme production in developing red cells so less protoporphyrin is made | Oral tablet | Once daily (60 mg in Phase 3 and expanded access) | Home; US expanded access program for ages 12 and up without satisfactory options | Studied in people aged 12 and up with EPP or XLP | Complete response letter February 13, 2026; Phase 3 APOLLO topline due October 19, 2026 |
PORT-77 PORT-77 | ABCG2 inhibitor: blocks the pump that moves protoporphyrin out of red cells into plasma | Oral tablet | Once or twice daily (dose being chosen in Phase 2b) | Clinical trial sites in the US | Recruiting people aged 12 and up with EPP or XLP for PATHWAY | Phase 2b/3 recruiting; not yet reviewed by the FDA |
Only Scenesse is FDA approved. Dersimelagon, bitopertin and PORT-77 are investigational and their results come from company announcements and trial registrations, not FDA labels; the FDA has not reviewed PORT-77 and declined bitopertin's first application. Trial results for different drugs measured different things over different periods and cannot be compared directly. Talk with a porphyria specialist about what fits your age, your liver and iron tests and your access to an accredited center.
Clinical trial results
INSPIRE (NCT06144840) was a global, randomized, double-blind, placebo-controlled Phase 3 trial in 165 people aged 12 to under 75 with EPP or XLP[3][4]. The primary endpoint was the average daily time in sunlight before the first prodromal symptom (tingling, stinging or burning) during weeks 12 to 16. Dersimelagon beat placebo by a least-squares mean difference of 23.19 minutes a day (p=0.004), and by 29.64 minutes at week 16 in a supplementary analysis (p=0.004)[3].
Key secondary endpoints were also met: the Patient Global Impression of Change score differed by -1.83 in favor of dersimelagon (p<0.001), and total pain events fell 39% compared with placebo (p=0.004)[3]. The results were presented as a late-breaker at the American Academy of Dermatology meeting on March 28, 2026[3]. Earlier, a Phase 2 trial (NCT03520036, 102 participants) and a first Phase 3 trial (NCT04402489, 184 participants) tested low and high doses against placebo; both are complete[4].
The open-label extension (NCT05005975) has 286 participants across 15 countries and runs to December 2027[5].
Main registered trial: NCT05005975 on ClinicalTrials.gov. Check it for the current status, sites and contacts before asking about enrollment.
Development history
Mitsubishi Tanabe Pharma discovered dersimelagon in house and received FDA Fast Track designation in June 2018, with Orphan Drug designation following[3]. The company, now Tanabe Pharma and owned by Bain Capital, announced the INSPIRE results on March 30, 2026 and said it was preparing a rolling NDA submission[3]. The NDA went to the FDA in June 2026[2].
On August 17, 2026 LEO Pharma, the Danish dermatology company, agreed to buy worldwide rights for up to USD 435 million in upfront and near-term milestone payments plus royalties[2]. On September 18, 2026 LEO announced that the FDA had accepted the NDA for filing with Priority Review and set a target action date by the end of February 2027, and that the acquisition had closed[1].
LEO's interim report describes a potential launch in 2027. Drugs@FDA showed no approval and the FDA's complete response letter database showed no letter for dersimelagon when this entry was checked on October 18, 2026[6].
Explore Erythropoietic Protoporphyria trials
Other Erythropoietic Protoporphyria treatments
Dersimelagon would join Scenesse as a second MC1R drug, taken as a daily pill instead of an implant every 2 months and studied down to age 12. The other 2 late-stage EPP drugs, bitopertin and PORT-77, aim at the protoporphyrin itself rather than at skin pigment.
Common questions about Dersimelagon
▸What is Dersimelagon?
A once-daily pill from LEO Pharma, developed by Tanabe Pharma, that works through the same skin-pigment receptor as the Scenesse implant. Its Phase 3 INSPIRE trial met its goal in adults and adolescents with EPP or XLP, and the FDA is reviewing it under priority review with a decision expected by the end of February 2027.
▸How does Dersimelagon work?
Dersimelagon is a small molecule taken by mouth that binds the melanocortin 1 receptor on the skin's pigment cells, the same receptor that the Scenesse implant activates with a peptide[3]. Activating MC1R increases melanin, which absorbs light before it reaches the protoporphyrin in the skin, so the tingling and burning that warn of a phototoxic reaction begin later[3][2]. Tanabe describes it as selective for MC1R over the related melanocortin receptors, and the expected on-target effects, darker skin and darker or new moles, showed up in the trial[3].
▸What are the side effects of Dersimelagon?
Tanabe reported that dersimelagon was generally well tolerated in INSPIRE, with a safety profile consistent with its mechanism[3]. The most common adverse events that occurred more often than with placebo were melanocytic nevi (benign moles), headache, nausea, diarrhea and skin hyperpigmentation[3]. Percentages by group, serious adverse events and discontinuations have not been released in a company statement, and there is no FDA label yet; the open-label extension study's primary measures include adverse events, physical examination findings and the appearance of moles[5]. Tanabe said the drug had been studied in 410 participants with EPP or XLP as of March 2026[3].
▸How is Dersimelagon taken?
In INSPIRE, participants took dersimelagon 200 mg or placebo by mouth once a day for 16 weeks, followed by 36 weeks of open-label active treatment[3]. The dose, strength and any food instructions for a marketed product will come with the FDA label if it is approved. Participants in the long-term extension study (NCT05005975) continue to receive the drug[5].
▸Is Dersimelagon FDA approved?
Not yet. Dersimelagon is under FDA review for Erythropoietic Protoporphyria; LEO Pharma has filed an application and a decision is expected by the end of February 2027. The FDA calendar page tracks the outcome.
▸When will the FDA decide on dersimelagon?
By the end of February 2027, according to LEO Pharma.
Status: the FDA accepted the application and granted Priority Review on September 18, 2026.
Exact date: not disclosed.
Source: LEO Pharma, September 18, 2026
▸How is dersimelagon different from Scenesse?
It is a daily pill, while Scenesse is an implant placed every 2 months, and it was studied from age 12 while Scenesse is approved for adults only.
Same target: both activate the MC1R receptor to add melanin to the skin.
Head to head: no trial has compared them.
Source: Tanabe Pharma, March 30, 2026; Scenesse prescribing information
▸How much more sun could people tolerate on dersimelagon?
About 23 more minutes a day before the first warning symptom, compared with placebo.
Trial: INSPIRE, 165 people with EPP or XLP, 16 weeks double blind.
Numbers: 23.19 minutes during weeks 12 to 16 (p=0.004) and 29.64 minutes at week 16; total pain events fell 39%.
Source: Tanabe Pharma, March 30, 2026
▸What were the side effects of dersimelagon in the trial?
The most common ones that occurred more often than with placebo were new moles, headache, nausea, diarrhea and skin darkening.
Severity: Tanabe said the drug was generally well tolerated; percentages by group have not been published in a company statement.
Label: none yet; full details will come if the FDA approves it.
Source: Tanabe Pharma, March 30, 2026
▸Who makes dersimelagon now?
LEO Pharma, which bought worldwide rights from Tanabe Pharma.
Deal: announced August 17, 2026, closed September 18, 2026, up to USD 435 million upfront and near-term milestones plus royalties.
Developer: Mitsubishi Tanabe Pharma (now Tanabe Pharma) discovered the drug and ran the trials.
Source: LEO Pharma, August 17 and September 18, 2026
Sources and references
Every factual claim on this page is drawn from the public sources listed below. Click any reference to open the original document.
- LEO Pharma A/S · 2026-09-18. LEO Pharma announces FDA acceptance of dersimelagon NDA with Priority Review and closes acquisition from Tanabe Pharma. https://leo-pharma.com/media-center/news/leo-pharma-announces-fda-acceptance-of-dersimelagon-nda-with-priority-review-and-closes-acquisition-from-tanabe-pharma/
- LEO Pharma A/S via Business Wire · 2026-08-17. LEO Pharma Further Strengthens Late-Stage Pipeline With the Acquisition of Dersimelagon. https://www.businesswire.com/news/home/20260817946702/en/LEO-Pharma-Further-Strengthens-Late-Stage-Pipeline-With-the-Acquisition-of-Dersimelagon
- Tanabe Pharma Corporation · 2026-03-30. Tanabe Pharma Announces Positive Data from Phase 3 INSPIRE Study of Dersimelagon in EPP and XLP. https://www.tanabe-pharma.com/en/news/rel_260330/main/0/link/e_rel_260330.pdf
- ClinicalTrials.gov · 2026-06-04. INcreased Sun Exposure Without Pain In Research Participants With EPP or XLP (INSPIRE). https://clinicaltrials.gov/study/NCT06144840
- ClinicalTrials.gov · 2026-09-09. Extension Study to Evaluate Safety and Tolerability of Oral Dersimelagon (MT-7117) in Subjects With EPP or XLP. https://clinicaltrials.gov/study/NCT05005975
- FDA via openFDA · 2026-10-18. openFDA Drugs@FDA query for dersimelagon (no approved application). https://api.fda.gov/drug/drugsfda.json?search=openfda.generic_name:%22dersimelagon%22