Study Evaluating the Mechanism of Action of PF-04965842 Monotherapy for Moderate-to-severe Atopic Dermatitis

Fold-Change From Baseline in Cellular (T-cell and Dendritic Cell) Inflammation Markers at Week 12

Mean fold-changes from baseline in immunohistochemistry analysis in lesional skin endpoints at Week 12 are presented. Fold-changes are computed by obtaining the antilog of log2 fold-changes, retaining the sign for log2 fold-change.

Time frame: Baseline, Week 12

Fold-Change From Baseline in Epidermal Hyperplasia Markers in Skin Biopsies and Skin Thickness at Week 12

Mean fold-changes from baseline in hyperplasia markers in skin biopsies at Week 12 are presented. Fold-changes are computed by obtaining the antilog of log2 fold-changes, retaining the sign for log2 fold-change.

Time frame: Baseline, Week 12

Fold-Change From Baseline in Blood Biomarkers for Inflammation and Immune Response at Week 12

OLINK Proteomics Microassay was used to analyze biomarkers in serum to assess the effect of abrocitinib on the blood biomarkers. Mean fold-changes at Week 12 from baseline are listed. Baseline is defined as the last observation on or prior to day of first dose (Day 1).

Time frame: Baseline, Week 12

Percent-Change From Baseline in T-cell Lymphocyte Subset Populations at Week 12

Mean percent changes from baseline at Week 12 in T-cell lymphocyte subset populations (CD3+ T cells, CD4+ T cells, CD8+ T cells, NK cells, B cells) are presented. Baseline is defined as the last observation on or prior to day of first dose (Day 1).

Time frame: Baseline, Week 12

Response Based on at Least 4 Points Improvement in the Severity of Peak Pruritus Numerical Rating Scale (NRS) From Baseline and Changes From Baseline in Immunohistochemistry (IHC) and Gene Expression Biomarkers in Lesional Skin

PP-NRS assesses the severity of itch (pruritus) due to AD. Participants were asked to assess their worst itching due to AD on an NRS anchored by the terms "no itch" (0) and "worst itch imaginable" (10). Participants who withdrew from the study were counted as non-responder. Spearman correlation coefficient was calculated to assess the relationship between PP-NRS CFB and fold CFB of IHC and gene expression biomarkers.

Time frame: Baseline, Week 12

Percentage of Participants Achieving Investigator's Global Assessment (IGA) Response of 'Clear' or 'Almost Clear' and >=2 Points Improvement From Baseline at Week 2, 4, 8 and 12

The IGA of AD is scored on a 5-point scale (0-4), reflecting a global consideration of the erythema, induration and scaling. The overall severity of AD was assessed according to the 5-point scale: 0=Clear, 1=Almost Clear, 2=Mild, 3=Moderate, and 4=Severe. Participants who withdrew from the study were counted as non-responder.

Time frame: Baseline, Weeks 2, 4, 8, and 12

Percentage of Participants Achieving Eczema Area and Severity Index (EASI) Response ≥ 75% Improvement From Baseline Week 2, 4, 8 and 12

The EASI quantifies the severity of AD based on both severity of lesion clinical signs and the percent of body surface area (BSA) affected. The EASI score can vary in increments of 0.1 and range from 0.0 to 72.0, with higher scores representing greater severity of AD. Participants who withdrew from the study were counted as non-responder.

Time frame: Baseline, Week 2, 4, 8, and 12

Percentage of Participants With >=4 Points at Baseline and Achieving >=4 Points Improvement From Baseline in Numeric Rating Scale for Severity of Pruritus (PP-NRS) at Weeks 2, 4, 8 and 12

PP-NRS assesses the severity of itch (pruritus) due to AD. Participants were asked to assess their worst itching due to AD on an NRS anchored by the terms "no itch" (0) and "worst itch imaginable" (10). Higher scores indicated worse itch. Participants who withdrew from the study were counted as non-responder.

Time frame: Baseline, Week 2, 4, 8, 12

Percentage of Participants Achieving EASI Response ≥ 90% Improvement From Baseline at Week 2, 4, 8 and 12

The EASI quantifies the severity of AD based on both severity of lesion clinical signs and the percent of BSA affected. The EASI score can vary in increments of 0.1 and range from 0.0 to 72.0, with higher scores representing greater severity of AD. Participants who withdrew from the study were counted as non-responder.

Time frame: Baseline to Week 2, 4, 8 and 12

Percentage of Participants Achieving EASI Response ≥ 50% Improvement From Baseline at Week 2, 4, 8 and 12

The EASI quantifies the severity of AD based on both severity of lesion clinical signs and the percent of BSA affected. The EASI score can vary in increments of 0.1 and range from 0.0 to 72.0, with higher scores representing greater severity of AD. Participants who withdrew from the study were counted as non-responder.

Time frame: Baseline to Week 2, 4, 8 and 12

Percent Change From Baseline in Percentage Body Surface Area (BSA) at Week 2, 4, 8 and 12

BSA efficacy is derived from the sum of the BSA in handprints across 4 body regions assessed as part of the EASI assessment. Handprint refers to that of each individual participant for their own measurement. The BSA efficacy ranges from 0 to 100%, with higher values representing greater severity of AD. The percentage BSA ranges from 0 to 100, with higher scores representing greater severity of AD. Since the scalp, palms, and soles were excluded from the BSA (efficacy) assessment, the maximum possible percentage BSA was less than 100.

Time frame: Baseline and Week 2, 4, 8 and 12

Number of Participants With Treatment Emergent Adverse Events (TEAEs)

An adverse event (AE) was any untoward medical occurrence in a clinical investigation participant administered a product; the event did not need to have a causal relationship with the treatment. TEAEs were AEs that occurred following the start of treatment or AEs increasing in severity during treatment. Treatment-related TEAEs were determined by the investigator.

Time frame: Baseline to 16 weeks

Number of Participants With Serious Adverse Events (SAEs)

A serious adverse event (SAE) was any untoward medical occurrence at any dose that resulted in death; was life threatening; required inpatient hospitalization or prolongation of existing hospitalization; resulted in persistent or significant disability/incapacity; resulted in congenital anomaly/birth defect. Treatment-related SAEs were determined by the investigator.

Time frame: Baseline to 16 weeks

Number of Participants Who Discontinued From the Study Due to TEAEs

An AE was any untoward medical occurrence in a clinical investigation participant administered a product; the event did not need to have a causal relationship with the treatment. TEAEs were AEs that occurred following the start of treatment or AEs increasing in severity during treatment. Treatment-related TEAEs were determined by the investigator.

Time frame: Baseline to 16 weeks

Number of Participants With Laboratory Test Abnormalities (Without Regard to Baseline Abnormality)

Laboratory tests included hematology (including coagulation panel), clinical chemistry, lipid profile panel, and routine urinalysis. LLN is lower limit of normal. ULN is upper limit of normal.

Time frame: Baseline to 16 weeks