A double-blind within-subject study to estimate observed application site adverse events following topical applications of crisaborole and vehicle in healthy participants

To further understand the potential for crisaborole to evoke skin irritancy, a within-subject comparison study, C3291042 will assess the local tolerability of crisaborole 5 mg/cm² in healthy participants, who have had baseline assessments of surrogate markers of skin sensitivity-i.e. current perception threshold (CPT) measurements and standardized lactic acid stinging test (LAST) assessments. To further the clinical understanding of application site pain, responses to crisaborole ointment compared to crisaborole vehicle ointment will be assessed in comparisons based upon CPT (low versus high; symmetry versus asymmetry) and response to LAST ("stingers" versus "non-stingers"). This exploration of skin sensitivity characterizations in healthy participants exposed to crisaborole 5 mg/cm² will assess application site burning, stinging, and pain as well as other application site characteristics selected from a MedDRA-based list of terms by the participants. More advanced understanding of baseline application site sensation in healthy participants prior to higher local application rate of topical crisaborole may provide strategies for topical dermatologic product development programs striving to prevent or minimize application site sensory adverse events.

Inclusion Criteria:

• Male and female adult participants who are overtly healthy as determined by medical evaluation including medical history, physical examination, and laboratory tests.

Exclusion Criteria:

• Prior self-reported history of any chronic relapsing inflammatory skin disease, including atopic dermatitis.
• Evidence or history of clinically significant hematological, renal, endocrine, pulmonary, gastrointestinal, cardiovascular, hepatic, psychiatric, neurological, or allergic disease (including drug allergies, but excluding untreated, asymptomatic, seasonal allergies at the time of dosing). Any clinically significant medical conditions or history of such conditions that, in the opinion of the Investigator may place the participant at an unacceptable risk as a participant in this trial.
• History of human immunodeficiency virus (HIV) infection, hepatitis B, or hepatitis C; positive testing for HIV, hepatitis B surface antigen (HBsAg), hepatitis B core antibody (HBcAb), or hepatitis C antibody (HCVAb). Hepatitis B vaccination is allowed.
• History of serious adverse reactions or hypersensitivity to any topical drug (eg, crisaborole); or known allergy to any of the test product(s) or any components (eg, lactic acid) in the test product(s) or history of hypersensitivity; or allergic reactions to any of the study preparations
• Abnormal physical findings of clinical significance or dermatological condition (eg extensive tattooing or excessive scarring at 14 sensitive skin application sites) at the Screening examination or Baseline which would interfere with the objectives of the study in the opinion of the Principal Investigator.
• Daily use of medications that could interfere with the objectives of the study (such as lidocaine, gabapentin, pregabalin, narcotics, antihistamines, oral or parenteral corticosteroids, non-narcotic analgesics and anti-inflammatories) within 1 week of screening and during the study.
• Not willing to refrain from shaving, the use of depilatories or other hair-removal activities, antiperspirants, lotions, skin creams, fragrances or perfumes, or body oils (eg, baby oil; coconut oil), use of hair products, hair gels, and hair oil in the treatment areas for 48 hours prior to admission to the PCRU and for the duration of the stay in the PCRU.

Pfizer will provide access to individual de-identified participant data and related study documents (e.g. protocol, Statistical Analysis Plan (SAP), Clinical Study Report (CSR)) upon request from qualified researchers, and subject to certain criteria, conditions, and exceptions. Further details on Pfizer's data sharing criteria and process for requesting access can be found at: https://www.pfizer.com/science/clinical\_trials/trial\_data\_and\_results/data\_requests.

Crisaborole 2% ointment and matching crisaborole vehicle will be supplied by Pfizer to the CRU as packaged 60 gram tubes and labeled according to local regulatory requirements in an unblinded fashion.

Crisaborole and vehicle ointment doses for the 14 pre-specified application sites bilaterally will be prepared by the unblinded PCRU pharmacist and provided to the blinded investigational site staff in individual dose containers. Subjects will be blinded to side of body treated with crisaborole and side of body treated with vehicle.