The aim of the study is to evaluate efficacy and safety of bimiralisib gel treatment for treatment of actinic keratosis (AK) on the face and/or scalp and/or back of hands

This is a multi-center, randomized, open label, parallel group study. The study products will be applied to the target lesions for a duration of 2 or 4 weeks of treatment.

The study consists of the following periods:

• Screening (up to 30 days)
• Treatment (2 or 4 weeks)
• Follow-Up (4 weeks)

Participants will be randomized to one of two groups (1:1):

• Arm A: Topical bimiralisib gel treatment for 2 weeks
• Arm B: Topical bimiralisib gel treatment for 4 weeks

Key Inclusion Criteria:

• Must be of at least 50 years of age, at the time of signing the informed consent.
• Have a clinical diagnosis of stable, clinically typical actinic keratosis.
• Have at least 3 actinic keratosis lesions contained within contiguous treatment regions of face and/or scalp and/or back of hands.
• Must agree not to use any product on the treatment area during the entire course of study except for Investigator-approved cleanser, sunscreen, wash, and non-medicated makeup.
• Must be willing to comply with sun avoidance measures for all exposed areas including use of Investigator-approved sunscreen and/or hats, have limited sun exposure time, and have no tanning bed use.
• Must be in good general health (ECOG 0-1)
• Participants of reproductive potential must agree to use double effective contraception from screening until 90 days after discontinuing study treatment.
• Female participants who had a menstrual cycle within 2 years prior to screening must have a negative serum pregnancy test at screening and a negative urine pregnancy test on their first treatment day.
• Must be capable of giving signed informed consent

Key Exclusion Criteria:

• Known or suspected hypersensitivity to any of the excipients of bimiralisib gel.
• Clinically atypical and/or rapidly changing actinic keratosis lesions in the treatment area.
• Clinical evidence of severe, uncontrolled autoimmune, cardiovascular, gastrointestinal, hematological, hepatic, neurologic, pulmonary or renal disease.
• Participation in any clinical research study within 30 days of the Baseline Visit.
• Cosmetic or therapeutic procedures (e.g. laser, peeling, photodynamic therapy, cryotherapy) within 4 weeks of the Baseline visit and within 2 cm of the selected treatment area.
• Use of sun lamps, tanning beds, and tanning booths during the 4 weeks prior to the Baseline Visit or planned use during the study.
• Use of any retinoids within 90 days of the Baseline Visit, or glucocorticosteroids, methotrexate or other anti-metabolites or nicotinamide within 28 days of the Baseline Visit.
• Any systemic cancer therapy or diagnosis within 6 months of the Baseline Visit.
• Any other malignancy within 5 years prior to Screening except basal or squamous cell carcinoma not in the treatment area that were treated with curative intent and are without recurrence.
• Other significant uncontrolled or unstable medical diseases or conditions that, in the opinion of the Investigator, would expose the participant to unacceptable risk by study participation