Multicenter Study to Assess the Efficacy and Safety of Methyl Aminolevulinate Hydrochloride (MAL) 16.8% Cream (CD06809-41) Versus Vehicle Cream for Actinic Keratosis of the Face

Inclusion Criteria: * Participants aged ≥ 18 years at the Screening visit. * Participants had at least 4, but no more than 12, clinically-confirmed thin or moderately thick, non-hyperkeratotic, non-pigmented AKs located on the face (e.g., forehead, cheek, chin), and balding scalp. * Female Participants of non-childbearing potential. * Participants fully understood and signed an ICF before any investigational procedure(s) are performed. Exclusion Criteria: * Participants with pigmented AK in the treatment areas. * Female participants who were pregnant, nursing, or planning a pregnancy during the study. * Participants with a clinical diagnosis of a skin disease other than AK. * Immunocompromised participants. * Participants with any condition that may be associated with a risk of poor protocol compliance.