Since the first clinical trials measuring treatment effects of afamelanotide in EPP, patients have consistently reported being able to spend several hours in sunlight without developing painful phototoxic reactions, as opposed to a few minutes before receiving the treatment. The recently published study by Barman-Aksözen et al. (2020) is the first one to systematically investigate the maximum time EPP patients under treatment with afamelanotide can spend in sunlight. In the Swiss EPP patient cohort (n=39), phototoxic burn tolerance time increased from median 10 min (range: 2 – 120 min) before treatment to 180 min under treatment (15 – 420 min), and all patients increased their time in sunlight by at least 1.8 -fold (1.8-fold to 180-fold, median: 15-fold; n=37, two patients with missing data). Concomitantly, their maximum pain scores as measured on a scale between 0 (no pain) and 10 (maximum possible pain) decreased from median 10 (8 – 10) at baseline to 4 (0 – 8) in the year 2018, when all investigated patients had access to the afamelanotide therapy. Further, during the three years observational time, Quality of Life as assessed by the disease specific instrument EPP-QoL remained at around 80 % and the treatment adherence rate was 97.4 %, which confirms results of previous studies in the Swiss, Italian and Dutch EPP patient cohorts (Biolcati et al. 2015, Wensink et al. 2020). The study therefore reflects and confirms patient reports about a near-normalisation of their lives. During the randomized controlled clinical trials, time in sunlight was measured, too. However, the results were expressed as an average over the entire trial period, i.e., minutes of sunlight exposure per day, regardless of the meteorological conditions or other circumstances limiting sunlight exposure during the trial period, like indoor occupation. Expressing results in that way does not reflect the patient experience with the treatment. Measuring the phototoxic burn tolerance time (PBTT) allows to assess the true extent of the protection against phototoxic reactions a treatment for EPP provides and better reflects its real benefit, especially from a patient perspective. The IPPN therefore strongly encourages researchers, drug developers, regulatory and access decision makers to consider PBTT as clinical end point to assess effectiveness of new therapies to address EPP.
