Trial Outcomes & Findings for A Target Occupancy Study With Ritlecitinib. (NCT NCT05128058)

A total of 16 participants were assigned to study treatment; 8 in the ritlecitinib 50 mg group and 8 in the ritlecitinib 200 mg group. All the participants were treated in this study.

A Target Occupancy Study With Ritlecitinib.

Target occupancy for janus kinase 3 (JAK3) in peripheral blood mononuclear cells (PBMCs) by ritlecitinib was investigated in human blood by chemical probe-based enrichment and liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) analysis. % TO is calculated as \[(baseline value - value at specified time point)\*100/baseline value\], where baseline value in this formula is defined as the mean of the two pre-dose measurements at Hour -1 and Hour 0 on Day 1. Since (baseline value - value at specified time point)=0 at baseline, % TO at baseline is 0.

Target occupancy for Bruton's tyrosine kinase (BTK) in PBMCs by ritlecitinib was investigated in human blood by chemical probe-based enrichment and LC-MS/MS analysis. % TO is calculated as \[(baseline value - value at specified time point)\*100/baseline value\], where baseline value in this formula is defined as the mean of the two pre-dose measurements at Hour -1 and Hour 0 on Day 1. Since (baseline value - value at specified time point)=0 at baseline, % TO at baseline is 0.

Target occupancy forIL 2 inducible T-cell kinase (ITK) in PBMCs by ritlecitinib was investigated in human blood by chemical probe-based enrichment and LC-MS/MS analysis. % TO is calculated as \[(baseline value - value at specified time point)\*100/baseline value\], where baseline value in this formula is defined as the mean of the two pre-dose measurements at Hour -1 and Hour 0 on Day 1. Since (baseline value - value at specified time point)=0 at baseline, % TO at baseline is 0.

Target occupancy for tyrosine kinase expressed in T cells (TXK) in PBMCs by ritlecitinib was investigated in human blood by chemical probe-based enrichment and LC-MS/MS analysis. % TO is calculated as \[(baseline value - value at specified time point)\*100/baseline value\], where baseline value in this formula is defined as the mean of the two pre-dose measurements at Hour -1 and Hour 0 on Day 1. Since (baseline value - value at specified time point)=0 at baseline, % TO at baseline is 0.

Target occupancy for tyrosine kinase expressed carcinoma (TEC) in PBMCs by ritlecitinib was investigated in human blood by chemical probe-based enrichment and LC-MS/MS analysis. % TO is calculated as \[(baseline value - value at specified time point)\*100/baseline value\], where baseline value in this formula is defined as the mean of the two pre-dose measurements at Hour -1 and Hour 0 on Day 1. Since (baseline value - value at specified time point)=0 at baseline, % TO at baseline is 0.

Target occupancy for bone marrow tyrosine kinase gene in chromosome X (BMX) in PBMCs by ritlecitinib was investigated in human blood by chemical probe-based enrichment and LC-MS/MS analysis. % TO is calculated as \[(baseline value - value at specified time point) \*100/baseline value\], where baseline value in this formula is defined as the mean of the two pre-dose measurements at Hour -1 and Hour 0 on Day 1. Since (baseline value - value at specified time point)=0 at baseline, % TO at baseline is 0.

Cmax is maximum observed plasma concentration. Cmax for ritlecitinib was observed directly from data.

Tmax is time for Cmax. Tmax for ritlecitinib was observed directly from data as time of first occurrence.

Clast is last quantifiable plasma concentration. Clast for ritlecitinib was observed directly from data.

Cav is average plasma concentration from time 0 to 24 hours over the 24 hours period. Cav for ritlecitinib was calculated as area under the plasma concentration-time curve from 0 to 24 hours (AUC24) divided by 24.

AUClast is area under the plasma concentration-time profile from time 0 to the time of the Clast. AUClast for ritlecitinib was determined using linear/log trapezoidal method.

AUC24 is area under the plasma concentration-time curve from time 0 to 24 hours. AUC24 for ritlecitinib was determined using linear/log trapezoidal method.

An AE was any untoward medical occurrence in a participant who received study treatment without regard to possibility of causal relationship. Treatment-related AE was any untoward medical occurrence attributed to study treatment in a participant who received study treatment. Relatedness to study treatment was assessed by the investigator. A serious adverse event (SAE) was an AE resulting in any of the following outcomes or deemed significant for any other reason: death; initial or prolonged inpatient hospitalization; life-threatening experience (immediate risk of dying); persistent or significant disability/incapacity; congenital anomaly. Treatment-emergent were events between first dose of study treatment and up to 35 days after last dose that were absent before treatment or that worsened relative to pretreatment state.

An AE was any untoward medical occurrence in a participant who received study treatment without regard to possibility of causal relationship. Treatment-related AE was any untoward medical occurrence attributed to study treatment in a participant who received study treatment. Relatedness to study treatment was assessed by the investigator. Treatment-emergent are events between first dose of study treatment and up to 35 days after last dose that were absent before treatment or that worsened relative to pretreatment state. AEs are classified according to the severity in 3 categories a) mild - AEs does not interfere with participant's usual function b) moderate - AEs interferes to some extent with participant's usual function c) severe - AEs interferes significantly with participant's usual function.

Laboratory parameters included: hematology (hemoglobin, hematocrit, erythrocyte, platelet, neutrophils, eosinophils, monocytes, basophils, lymphocytes, etc), chemistry (glucose, calcium, sodium, potassium, chloride, total bilirubin, aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, protein, albumin, etc), and urinalysis (glucose, protein, hemoglobin, ketones, nitrite, leukocytes, urine bacteria, etc). Baseline = the pre-dose measurement on Day -1. Laboratory abnormalities meeting pre-defined criteria are reported for this outcome measure. Only those categories in which at least 1 participant had data were reported. ULN=upper limit of normal. LPF=low power field.

Pre-defined criteria included: 1) Diastolic blood pressure (DBP), a) supine DBP: less than (\<) 50 mmHg, b) supine DBP: change of \>= 20mmHg increase, c) supine DBP: change of \>= 20mmHg decrease; 2) Systolic blood pressure (SBP), a) supine SBP: \<90 mmHg, b) supine SBP: change of \>=30mmHg increase, c) supine SBP: change of \>=30mmHg decrease; 3) Supine pulse rate, a) \<40 bpm, b) \>120 bpm. mmHg=millimeters of mercury, bpm=beats per minute.