Study To Assess Local Tolerability of Crisaborole 2% Ointment and Vehicle Ointment In Healthy Participants Using Subject-reported Assessments and Objective Measurements

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.