An Open-label, DDI Study to Investigate the Effects of Duvakitug on the PK of Selected Cytochrome P450 Substrates

This is an open-label, single group, 2-period, Phase 1, single-arm study. The primary purpose of this study is to investigate the effects of duvakitug on the pharmacokinetics of selected cytochrome P450 substrates in adult participants with moderately to severely active ulcerative colitis or Crohn's disease. Approximately 25 participants will be enrolled. The total study duration per participant will be approximately 166 days.

Inclusion Criteria: * Participants aged ≥18 and ≤65 years (both inclusive) of age at Screening. * Ulcerative colitis (UC) participants only: * Confirmed diagnosis of UC for at least 3 months prior to Screening. * Active UC with a modified Mayo Score of 5 to 9 points and Mayo Endoscopic Subscore of 2 to 3 at Screening (historical endoscopy within 3 months of screening). If no data are available or if available historical endoscopy data are deemed insufficient to determine clinical status, an endoscopy will be performed at Screening. * Crohn's Disease (CD) participants only: * Confirmed diagnosis of CD for at least 3 months prior to Screening. * Participants with moderately to severely active CD, defined as: 1. Persistently active disease with a Crohn's Disease Activity Index score of 220 to 450, with endoscopic Simple Endoscopic Score for Crohn's Disease score (excluding the presence of narrowing component) ≥6 (or ≥4 for participants with isolated ileal disease), (historical endoscopy within 3 months of Screening). If no data are available, an endoscopy will be performed at Screening. 2. Average daily very soft or liquid stool frequency ≥4.0 and/or average daily abdominal pain score ≥2.0 at Screening. * Demonstrated inadequate response, loss of response or intolerance to conventional therapies or advanced therapies, in the opinion of the Investigator to at least 1 of following approved treatments: Conventional therapies * Immunomodulators (eg, AZA, 6-MP, MTX, tacrolimus, thioguanine). * IV or oral corticosteroids. Advanced therapies * Biologics (eg, infliximab, golimumab, adalimumab, certolizumab pegol, natalizumab, vedolizumab, risankizumab, guselkumab, mirikizumab, ustekinumab) * JAKi (eg, upadacitinib). * S1PRm (eg, ozanimod, etrasimod). * Participant must weigh \>40 kg. Exclusion Criteria: * For ulcerative colitis (UC) participants only: * Participant with a current diagnosis of CD or indeterminate colitis. * Participant with a current diagnosis of ulcerative proctitis (disease limited to the rectum) during the screening endoscopy and in the available endoscopic report. * Participant with surgical bowel resection within the past 3 months prior to Screening, or a history of \>3 bowel resections. * Crohn's Disease (CD) participants only: --Participant with a current diagnosis of UC or indeterminate colitis. * Participant with the following current complications of UC or CD: * Abscess (abdominal or peri-anal), * Impassable or symptomatic bowel strictures, * Fulminant colitis, or toxic megacolon, or * Any other manifestation that might require surgery while enrolled in the study. * Participant with ostomy or ileoanal pouch. * Participant diagnosed with short bowel syndrome. * Poor metabolizers for cytochrome P450 (CYP) 2C9, CYP2C19, or CYP2D6 based on genotyping. Participants who do not consent to this required CYP genotype testing will be excluded from the study. * Any contraindication to one or more of the following CYP cocktail study interventions, according to the applicable labeling: * Caffeine. * Metoprolol. * Midazolam. * Omeprazole. * Warfarin. * Vitamin K. The above information is not intended to contain all considerations relevant to a participant's potential participation in a clinical trial.