title: Vemurafenib skin phototoxicity is indirectly linked to ultraviolet A minimal erythema dose decrease.
abstract: BACKGROUND
  Vemurafenib, an anti-rapidly accelerated fibrosarcoma kinase B (BRAF) molecule, improves survival among patients with metastatic BRAF-mutated melanoma. Photosensitivity, a frequent cutaneous adverse effect induced by vemurafenib, can lead to cessation of treatment.
  
  
  OBJECTIVE
  To investigate photosensitivity mechanisms in patients treated with vemurafenib for metastatic melanoma.
  
  
  METHODS
  In a prospective study of 12 patients, photobiological explorations with measurements of ultraviolet A (UVA) minimal erythema dose (MED) and polychromatic MED were performed over 3 days in all 12 patients. UVA MED and polychromatic MED were also assessed for four patients before treatment. We then performed spectrophotometric analyses of (i) serum and faeces in these four patients, before and after introduction of vemurafenib; (ii) the lyophilized form of vemurafenib without excipient added; and (iii) the lyophilized form of vemurafenib added to serum and faeces before treatment.
  
  
  RESULTS
  Photosensitivity was present in 92% of the patients. UVA MED was normal before treatment and decreased after treatment, while polychromatic MED remained normal. The same three peaks (210, 260 and 310 nm) were identified in the spectrum for UVB and UVC but not for UVA on spectrophotometric analyses for each condition (lyophilized vemurafenib; serum and faeces after introduction of vemurafenib; and lyophilized vemurafenib added to serum and faeces before treatment). The peaks were different before treatment.
  
  
  CONCLUSIONS
  Our study confirms that photosensitivity under vemurafenib treatment was a UVA phototoxicity reaction, and our results suggest that a metabolite of vemurafenib rather than the parent molecule is involved in this phototoxicity.
authors: Department of Dermatology, CHU Caen, Caen, F-14000, France; Université Caen Basse-Nomandie, Medical School, Caen, F-14000, France.
authors: C
authors: C
authors: Brugière
authors: A
authors: A
authors: Stefan
authors: C
authors: C
authors: Morice
authors: E
authors: E
authors: Cornet
authors: A
authors: A
authors: Moreau
authors: S
authors: S
authors: Allouche
authors: L
authors: L
authors: Verneuil
mesh_terms: D000328:Adult; D000368:Aged; D000970:Antineoplastic Agents / Q000009:adverse effects*; D017484:Dermatitis, Phototoxic / Q000209:etiology*; D004307:Dose-Response Relationship, Radiation; D004890:Erythema / Q000209:etiology*; D005260:Female; D006801:Humans; D007211:Indoles / Q000009:adverse effects*; D008297:Male; D008545:Melanoma / Q000188:drug therapy*; D008875:Middle Aged; D011446:Prospective Studies; D012878:Skin Neoplasms / Q000188:drug therapy*; D013449:Sulfonamides / Q000009:adverse effects*; D014466:Ultraviolet Rays / Q000009:adverse effects*; D000077484:Vemurafenib
chemical_list: D000970:Antineoplastic Agents; D007211:Indoles; D013449:Sulfonamides; D000077484:Vemurafenib