Risk of Squamous Cell Carcinoma on Skin Areas Treated With Ingenol Mebutate Gel, 0.015% and Imiquimod Cream, 5%

Inclusion Criteria:

1. Signed Informed Consent Form (ICF) prior to any trial-related procedures
2. Subjects with 5 to 9 clinically typical, visible and discrete AKs within a contiguous 25 cm² treatment area on the face or scalp.
3. Subject at least 18 years of age
4. Female subjects must be of either:

   1. Non-childbearing potential, or,
   2. Childbearing potential, provided there is a confirmed negative urine pregnancy test
5. Female subjects of childbearing potential must be willing to use highly effective methods of contraception (Pearl index \< 1%)

Exclusion Criteria:

1. Location of the selected treatment area:

   * on the periorbital skin
   * on the perioral skin/around the nostrils
   * within 5 cm of an incompletely healed wound
   * within 10 cm of a suspected BCC or SCC or other neoplasia
2. Selected treatment area lesions that have atypical clinical appearance (e.g., hypertrophic, hyperkeratotic or cutaneous horn).
3. History of SCC, BCC, malignant melanoma or other neoplasia in the selected treatment area.
4. History or evidence of skin conditions other than the trial indication that would interfere with evaluation of the trial medication in the selected treatment area
5. Use of ingenol mebutate and/or imiquimod in and within 5 cm of the selected treatment area within 2 years prior to Screening (Visit 1)
6. Organ transplant recipients
7. Immunosuppressed subjects (for example HIV patients)
8. Female subjects who are breastfeeding.
9. Subjects who are institutionalised by court order or by the local authority
10. 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)