This Phase II study is to evaluate the efficacy of SR-T100 gel with 2.3% of SM in Solanum undatum plant extract in patient with Actinic Keratosis (AK).

Inclusion Criteria:

1. Male or female; aged ≥ 18 years old.
2. Patient who accepts to enter the study by signing written informed consent.
3. Patient has 4 to 8 clinically diagnosed, discrete, non-hyperkeratotic, non-hypertrophic AK, located with or without a contiguous 25cm2 areas.
4. Patient allows biopsy to be performed on selected lesion.
5. Patient agrees to apply the study medication on prescribed treatment area with an occlusive dressing at least 20 hours per day.
6. Patient agrees photographs to be taken on selected lesion and used as part of the study data package.
7. Patient in good general health condition (performance status ≤ 2 Eastern Cooperative Oncology Group (ECOG).
8. Sexually active female patient with child-bearing potential must take reliable contraception method(s) during the participation of the study.

Exclusion Criteria:

1. Patient with recurrent invasive squamous cell carcinoma (SCC).
2. Patient has grossly suspicious or inflamed lymph nodes on physical examination.
3. Patient has evidence of clinically significant or unstable medical conditions.
4. Patient has any skin condition in the treatment area that may be made worse by treatment.
5. Patient currently uses or had used on the treatment area(s) OTC retinol products, corticosteroids, cryosurgery, curettage, 5-fluorouracil (5-FU), imiquimod, topical diclofenac, retinoids, or other topical AK treatments (such as laser abrasion, dermabrasion, glycolic acids, or chemical peels) 28 days prior to screening visit.
6. Patient had received systemic cancer chemotherapy or immunosuppressant; on the target evaluation area that psoralen plus UVA therapy, UVB therapy were treated 6 months prior to screening visit.
7. Patient currently uses or has used prednisone and/or prednisolone (≥ 10 mg or the equivalent) more than 2 weeks continuously within 12 weeks prior to randomization visit.
8. Engaging in activities involving excessive or prolonged exposure to sunlight.
9. History of allergy or sensitivity to related compounds or other components of the investigational product formulation.
10. Woman who is pregnant, lactating or planning to become pregnant during the study.
11. Patient used any investigational drug within 8 weeks prior to the screening visit.