The main objective of this study is to evaluate the dose-response relationship of two concentrations of A-101 solution when applied to individual seborrheic keratosis (SK) lesions (target lesions) compared with a matching A-101 Solution Vehicle.

The main objective of this study is to evaluate the dose-response relationship of two concentrations of A-101solution when applied to individual seborrheic keratosis (SK) lesions (target lesions) compared with a matching A-101 Solution Vehicle.

Each subject will have 4 target lesions on the trunk/extremities.

A further objective is to evaluate the safety and efficacy of two concentrations of A-101 solution and its matching vehicle when applied to SK target lesions on the trunk/extremities.

Inclusion Criteria:

1. Subject is at least 18 years of age

2. Subject has a clinical diagnosis of stable clinically typical seborrheic keratosis

3. Subject has 4 appropriate seborrheic keratosis target lesions, as defined below, on the trunk/extremities:

   • Have a clinically typical appearance
   • Be treatment naïve
   • Have a Physician Lesion Assessment (PLA) of ≥2
   • Have a longest axis that is ≥7mm and ≤15mm
   • Have a longest dimension perpendicular to the longest axis that is ≥7mm and ≤15mm
   • Have a thickness that is ≤2mm
   • Be a discrete lesion
   • Be, when centered in the area outlined by the provided 3cm diameter circular template, the only seborrheic keratosis lesion present
   • Not be in an intertriginous fold
   • Not be in an area where clothing, such as a bra, might cause physical irritation
   • Not be pedunculated.

4. If the subject is a woman of childbearing potential, she has a negative urine pregnancy test and agrees to use an active form of birth control for the duration of the study

5. Subject is non-pregnant and non-lactating

6. Subject is in good general health and free of any known disease state or physical condition which, in the investigator's opinion, might impair evaluation of any target lesion or which exposes the subject to an unacceptable risk by study participation

7. Subject is willing and able to follow all study instructions and to attend all study visits

8. Subject is able to comprehend and willing to sign an Informed Consent Form (ICF).

Exclusion Criteria:

1. Subject has clinically atypical and/or rapidly growing seborrheic keratosis lesions

2. Subject has presence of multiple eruptive seborrheic keratosis lesions (Sign of Leser-Trelat)

3. Subject has a current systemic malignancy

4. Subject has a history of keloid formation or hypertrophic scarring

5. Subject has used any of the following systemic therapies within the specified period prior to Visit 1:

   • Retinoids; 180 days
   • Glucocorticosteroids; 28 days
   • Anti-metabolites (e.g., methotrexate); 28 days

6. Subject has used any of the following topical therapies within the specified period prior to Visit 1 on, or in a proximity to the target lesion, that in the investigator's opinion, interferes with the application of the study medication or the study assessments:

   • LASER, light (e.g., intense pulsed light (IPL), photo-dynamic therapy (PDT)) or other energy based therapy; 180 days
   • Retinoids; 90 days
   • Liquid nitrogen, electrodesiccation, curettage, imiquimod, 5-fluorouracil, or ingenol mebutate; 60 days
   • Glucocorticosteroids or antibiotics; 14 days
   • Moisturizers/emollients, sunscreens; 12 hours

7. Subject currently has or has had any of the following within the specified period prior to Visit 1 on or in a proximity to the target lesion that, in the investigator's opinion, interferes with the application of the study medication or the study assessments:

   • A cutaneous malignancy; 180 days
   • Experienced a sunburn; 28 days
   • A pre-malignancy (e.g., actinic keratosis); currently
   • Body art (e.g., tattoos, piercing, etc.); currently
   • Excessive tan; currently

8. Subject has a history of sensitivity to any of the ingredients in the study medications

9. Subject has any current skin disease (e.g., psoriasis, atopic dermatitis, eczema, sun damage, etc.), or condition (e.g., sunburn, excessive hair, open wounds) that, in the opinion of the investigator, might put the subject at undue risk by study participation or interfere with the study conduct or evaluations

10. Subject has participated in an investigational drug trial in which administration of an investigational study medication occurred within 30 days prior to Visit 1.

From subject's first study medication application to the end of the study (visit 8), up to 106 days. the end of the subject's last visit. 106.

An adverse event (AE) is any untoward medical occurrence in a patient or clinical investigation subject administered a study medication(s) and which does not necessarily have a causal relationship with the study medication. Thus any new, clinically relevant worsening of an existing sign, symptom or disease, should be considered an AE.