Dersimelagon (MT-7117): the oral MC1R agonist chasing the afamelanotide target

The system asked to do two of its jobs at once — an MC1R pill chasing both the light-sensitive and the inflamed.

Dersimelagon — development code MT-7117 — is what happens when you take the afamelanotide idea and try to put it in a pill. It aims at the same target, MC1R, with the same strategy — build protective pigment to defend against light — but as an oral small-molecule drug rather than an injected peptide implant.^[1] That shift, from injected peptides to pills, is the move the whole melanocortin pipeline is now making — and dersimelagon is one of the first to show it can work.

Same target, different form

Afamelanotide proved that switching on MC1R can treat the light-sensitivity disease erythropoietic protoporphyria, but it does so as a two-monthly implant placed by a clinician. Dersimelagon is the attempt to deliver the same benefit more conveniently: a once-daily tablet a patient can take at home.^[1] Because it is a small molecule rather than an α-MSH-like peptide, it can be absorbed orally — a meaningful practical difference for a chronic, preventive therapy.

The Phase 3 result

Dersimelagon's lead program is in EPP and the related disorderX-linked protoporphyria (XLP). Its pivotal trial,INSPIRE, was a global, randomised, double-blind, placebo-controlled Phase 3 study in 165 adults and adolescents (ages 12–75), comparing dersimelagon 200 mg once daily against placebo over 16 weeks, with a 36-week open-label extension.^[4] Its primary endpoint was the one that actually matters in this disease: the change in average daily time in sunlight before the first prodromal symptom — how long a patient can stay in the light before the warning signs of a phototoxic reaction begin.^[4]

In January 2026, Tanabe Pharma America reported that INSPIREmet its primary endpoint with a favourable safety profile — the key clinical milestone on dersimelagon's path toward becoming an oral option alongside the approved implant.^[3] Full trial data had not yet been published at the time of writing and regulatory filings were still awaited, but the program already carries FDA Fast Track (2018) and Orphan Drug (2020) designations.^[3] As with every drug in this family, the most common side effects were mechanism-based pigment changes — skin hyperpigmentation and freckle-like lentigines, the expected signature of MC1R activation.^[1]

A second life in fibrosis

Dersimelagon's more surprising story is outside pigment biology altogether. Preclinical research shows that MC1R activation can produce disease-modifying, anti-fibrotic effects in models of systemic sclerosis — a serious autoimmune disease in which skin and internal organs become scarred and stiff.^[2] The reason it can reach beyond the skin is that MC1R sits not only on pigment cells but on the immune cells, blood-vessel lining, and fibroblasts that drive the disease; in these models dersimelagon acted on all three at once — damping inflammation, easing vascular dysfunction, and suppressing the fibrosis itself.^[2]

That rationale has moved into people: a Phase 2 proof-of-concept study enrolled 73 patients with diffuse cutaneous systemic sclerosis (dcSSc).^[5] It is an early but striking example of the same receptor being pointed at a completely different disease — the pigment switch repurposed as an anti-fibrotic.

The honest bottom line

Dersimelagon is investigational — a positive Phase 3 topline is not the same as approval, full INSPIRE data are still to come, and the fibrosis programme is only at Phase 2. But it captures two live themes on the melanocortin frontier: making these drugs easier to take (a pill instead of an implant), and pushing MC1R beyond pigment into inflammation and fibrosis. For the approved drug it is chasing, see afamelanotide; for the broader anti-inflammatory arm its fibrosis work belongs to, see the inflammation axis; for why swallowing a peptide is so hard in the first place, see the route problem; and for where it sits among everything else in development, see the melanocortin pipeline.

Common questions

What is dersimelagon?+

Dersimelagon (MT-7117) is an investigational oral drug that activates the MC1R pigment receptor. Unlike afamelanotide, which is an injected implant, dersimelagon is a small-molecule tablet — a once-daily pill being developed for the same light-sensitivity disease, erythropoietic protoporphyria, and for the fibrotic disease systemic sclerosis.

How is dersimelagon different from afamelanotide?+

They hit the same target (MC1R) with the same basic strategy — build protective pigment — but in different forms. Afamelanotide is an approved α-MSH-like peptide delivered as a two-monthly implant; dersimelagon is an investigational small molecule you swallow. If approved, it would offer an oral alternative to the implant.

What is dersimelagon being tested for?+

Two things. First, erythropoietic protoporphyria (EPP) and X-linked protoporphyria (XLP), where its global Phase 3 INSPIRE trial (165 patients, once-daily 200 mg) met its primary endpoint in January 2026. Second, diffuse cutaneous systemic sclerosis, a fibrotic disease, where a Phase 2 proof-of-concept study (73 patients) is testing whether MC1R activation has disease-modifying, anti-fibrotic effects.

What are dersimelagon’s side effects?+

They are mechanism-based and predictable from the target: activating MC1R increases pigment, so the most common effects in trials were skin hyperpigmentation and freckle-like lentigines. These are the same family-resemblance pigment effects seen across melanocortin agonists.

References

1. 1.PubMed. Results from a first-in-human study of dersimelagon, an investigational oral selective MC1R agonist. First-in-human pharmacology and tolerability of MT-7117. 2023. link ↗
2. 2.Open-access study (PMC). Dersimelagon, a novel oral melanocortin 1 receptor agonist, demonstrates disease-modifying effects in preclinical models of systemic sclerosis. Preclinical evidence for MC1R activation in fibrosis. 2022. link ↗
3. 3.Tanabe Pharma America. Positive topline results for dersimelagon in erythropoietic protoporphyria (EPP) and X-linked protoporphyria (XLP). Phase 3 INSPIRE trial press release. 2026. link ↗
4. 4.ClinicalTrials.gov. Efficacy, safety, and tolerability of MT-7117 in subjects with erythropoietic protoporphyria or X-linked protoporphyria (INSPIRE). Phase 3 INSPIRE trial record (NCT04402489) — 165 patients, 200 mg once daily vs placebo, 16-week primary period + 36-week open-label extension; primary endpoint = daily sunlight exposure to first prodromal symptom. 2026. link ↗
5. 5.ClinicalTrials.gov. Efficacy, safety, and tolerability of MT-7117 in subjects with diffuse cutaneous systemic sclerosis. Phase 2 proof-of-concept trial record (NCT04440592) in dcSSc. 2024. link ↗