The disease leaves the body unable to finish making heme, so a precursor called protoporphyrin builds up and reacts with light reaching the skin. Researchers tested whether a peptide that darkens skin pigment without needing UV exposure could extend the time patients could tolerate daylight.
In the peer-reviewed US trial of 94 patients, those given an afamelanotide implant every 60 days spent a median of 69.4 hours in direct sunlight without pain over six months, against 40.8 hours on placebo. A parallel EU trial of 74 patients also found longer pain-free sun exposure, and both reported better quality of life.
The peptide works by activating the same receptor that triggers melanin production, independent of sun exposure, so it darkens skin and may offer some protection without the light exposure that causes patients pain. It does not cure the underlying metabolic defect, and most patients still need to limit direct sunlight, just for longer stretches.
Read the original study
Langendonk et al., New England Journal of Medicine, 2015 · doi.org/10.1056/NEJMoa1411481
More daylight, without the pain.
Source
- Langendonk, J. G., Balwani, M., Anderson, K. E., Bonkovsky, H. L., Anstey, A. V., Bissell, D. M., Bloomer, J., Edwards, C., Neumann, N. J., Parker, C., Phillips, J. D., Lim, H. W., Hamzavi, I., Deybach, J.-C., Kauppinen, R., Rhodes, L. E., Frank, J., Murphy, G. M., Karstens, F. P. J., . . . Desnick, R. J. (2015). Afamelanotide for Erythropoietic Protoporphyria. New England Journal of Medicine, 373(1), 48–59. https://doi.org/10.1056/NEJMoa1411481