Enzalutamide induced acute generalized exanthematous pustulosis

Enzalutamide (Xtandi®) is a new potent inhibitor of the signaling pathway for the androgen receptor with a half-life of 5.8 days. It has been on the market for the treatment of metastatic castration-resistant prostate cancer since November 2013.

We report the first case of acute generalized exanthematous pustulosis (AGEP) induced by enzalutamide.

A 62-year-old male patient with no significant medical history, was diagnosed in April 2014 with metastatic prostatic adenocarcinoma. In April 2015 the patient received a second line oral therapy with enzalutamide, 160 mg/day, coupled with a subcutaneous implant of 10.8 mg of goserelin, an agonist analog of natural luteinising hormone releasing hormone (LH-RH). Ten days after starting enzalutamide treatment and four days after introduction of first goserelin subcutaneous implant, the patient experienced an acute skin reaction. It is about of the plaques covered with widespread millimetric non-follicular pustules. Complete resolution of skin lesions occurred within four weeks. According to the AGEP validation score of the European Study of Severe Cutaneous Adverse Reactions, the total score in the current case was 7, interpreted as probable AGEP. According to criteria that assess adverse drug reactions, it was concluded that enzalutamide was responsible for this case of AGEP (suggestive imputation).

Dermatologist can be confronted with adverse skin drug reactions attributable to new therapeutic molecules. The slow resolution of symptoms seems be due to the long half-life of enzalutamide.