Ingenol mebutate: from common weed to cancer cure.

Actinic keratosis, which is a potential precursor of squamous cell carcinoma, is a common skin condition in fair-skinned adults worldwide. Actinic keratosis may be treated with 'lesion-directed' approaches and/or 'field-directed' therapies, the latter of which include imiquimod, diclofenac and 5-fluorouracil. The topical formulation of ingenol mebutate, which is a protein kinase C inhibitor derived from the sap of the plant Euphorbia peplus, is the newest addition to the existing arsenal of field-directed treatments. Its mechanism of action primarily involves the induction of primary necrosis and initiation of an inflammatory response characterized by the migration of neutrophils to the treated area. The gel is available in two strengths: 150 micrograms/g to be applied to lesions on the face and scalp once daily for 3 consecutive days and 500 micrograms/g for application to lesions on the trunk and extremities for 2 consecutive days. Clinical studies have supported claims of the convenience of its application and efficacy; however, the literature provides scant information on comparative efficacy rates and side-effect profiles.