Safety and Efficacy of Ingenol Mebutate Once Daily for 2 or 3 Consecutive Days in Subjects With Actinic Keratosis

Inclusion Criteria: * Subjects must be competent to understand the nature of the trial and provide informed consent * Part 1: Subjects with 5 to 20 clinically typical, visible and discrete AKs on the face Part 2: Subjects with 5 to 20 clinically typical, visible and discrete AKs on either the face, the balding scalp (the balding part of the scalp should be at least 25 cm2) or a contiguous area of approximately 250 cm2 on the chest * Subject at least 18 years of age * Female subjects must be of either: 1. Non-childbearing potential, i.e. post-menopausal or have a confirmed clinical history of sterility (e.g. the subject is without a uterus) or, 2. Childbearing potential, provided there is a confirmed negative urine pregnancy test prior to trial treatment, to rule out pregnancy * Female subjects of childbearing potential1 must be willing to use effective contraception at trial entry and until completion Exclusion Criteria: * Location of the treatment area (full face, full balding scalp or chest) * within 5 cm of an incompletely healed wound, * within 10 cm of a suspected basal cell carcinoma (BCC) or squamous cell carcinoma (SCC * Prior treatment with ingenol mebutate gel within the treatment area * Lesions in the treatment areas that have: * atypical clinical appearance (e.g., hypertrophic, hyperkeratotic or cutaneous horns) and/or, * recalcitrant disease (e.g., did not respond to cryotherapy on two previous occasions * History or evidence of skin conditions other than the trial indication that would interfere with the evaluation of the trial medication (e.g., eczema, unstable psoriasis, xeroderma pigmentosum) * Use of cosmetic or therapeutic products and procedures which could interfere with the assessments of the treatment areas. * Clinical diagnosis/history or evidence of any medical condition that would expose a subject to an undue risk of a significant AE or interfere with assessments of safety and efficacy during the course of the trial, as determined by the investigator's clinical judgment * Any abnormal laboratory tests that are medically significant and would impact the safety of the subjects or the interpretation of the trial results, as determined by the investigator's judgment * Anticipated need for hospitalisation or out-patient surgery during the first 15 days after the first trial medication application. Note that cosmetic/therapeutic procedures are not excluded if they fall outside of the criteria detailed in Prohibited Therapies or Medications * Known sensitivity or allergy to any of the ingredients in ingenol mebutate gel * Presence of acute sunburn within the treatment areas * Current enrolment or participation in an investigational clinical trial within 30 days of entry into this trial. * Subjects previously assigned to treatment in Part 1 or rand * Female subjects who are breastfeeding. * In the opinion of the investigator, the subject is unlikely to comply with the Clinical Study Protocol (e.g. alcoholism, drug dependency or psychotic state)