Double Blind, Placebo-controlled Trial to Establish Safety and Efficacy of Ritlecitinib in Celiac Disease Patients in Remission

Subjects include: aged 18 to 75 years, inclusive, have biopsy-confirmed disease that is clinically inactive as determined by negative celiac disease (CeD) serology and histology (determined via endoscopy at time of screening), have followed a gluten-free diet (GFD) for ≥6 months as reported by the subject, and be human leukocyte antigen (HLA)-DQ2.5 and/or HLA-DQ8 positive. Study involves the following randomized intervention; 10g gluten + 200mg of Ritlecitinib or placebo

Inclusion Criteria: 1. Male and/or female subjects (including Women of Childbearing Potential (WOCBP)) ≥18 years to ≤75 years of age at the time of informed consent 2. Have a body mass index ≥17 to \45 kg at the Screening Visit). 3. Agree to make every effort to avoid pregnancy (see lifestyle outline below) from the time of signing the informed consent throughout the duration of the trial, if the subject is a woman of childbearing potential and sexually active with a non-sterilized male partner. 4. Have well controlled biopsy-proven CeD, compliant with a GFD for ≥6 months preceding Screening, with resolution of CeD symptoms, normalization of CeD serology (defined as \5 stools/day), and/or prolonged symptoms (duration \>7 days). 2. A history of any abdominal or pelvic surgery \3 months before trial enrollment. 3. Subjects considered in imminent need for surgery or with elective surgery scheduled to occur during the study 4. Have a positive or borderline positive IgA anti-tissue transglutaminase serology at Screening (defined as \>/= 2 times the upper limit of normal). 5. Have Marsh 3a-c determined by pathology at Screening Endoscopy 6. A diagnosis of any other inflammatory gastrointestinal disorder 7. Ongoing immunosuppression or receive any treatment within 3 months the starting of the trial that might alter T cell repertoire or phenotype. 8. Has a confirmed history of a SARS-CoV-2 infection within the previous 2 months of the screening visit. 9. Any history of either untreated or inadequately treated latent or active TB infection by Interferon Gamma Release Assay during screening or within 12 weeks prior to randomization, current treatment for active or latent TB infection or evidence of currently active TB by chest x-ray, residing with or frequent close contact with individual(s) with active TB. 10. Positive screening for HIV, Hepatitis B, Hepatitis C.