A Study of TAK-062 in Treatment of Active Celiac Disease in Participants Attempting a Gluten-Free Diet

The drug being tested in this study is called TAK-062. TAK-062 is designed to break down gluten in the stomach and is being tested to treat people who have active CeD, attempting to maintain a GFD. The study will enroll approximately 357 patients. Participants will be randomly assigned (by chance, like flipping a coin) to one of the two treatment groups in Cohort 1: 1. Cohort 1 (Age 18 and older): TAK-062 Placebo + SIGE Gluten-Bar 2. Cohort 1 (Age 18 and older): TAK-062 Dose 1 + SIGE Gluten-Bar After the interim analysis (IA), Cohort 1 data will be reviewed by an external independent data monitoring committee (DMC), and based on the Sponsor's decision, adolescent participants will be enrolled in Cohort 2. Adult participants, 18 years and older will be enrolled into Cohort 2 once Cohort 1 has completed enrolment. Adult participants will be randomly assigned to one of the five study drug and SIGE treatment groups (Groups a-e), and approximately 21 adolescent participants will be enrolled and randomly assigned to Groups d, e, and f (adolescents only). Adolescents in Cohort 2 will receive only gluten-free SIGE bars. 1. Cohort 2 (Age 18 and older): TAK-062 Placebo + SIGE Gluten-Bar 2. Cohort 2 (Age 18 and older): TAK-062 Dose 2 + SIGE Gluten-Bar 3. Cohort 2 (Age 18 and older): TAK-062 Dose 3 + SIGE Gluten-Bar 4. Cohort 2 (Age 12 and older): TAK-062 Placebo + Gluten-free SIGE Bar 5. Cohort 2 (Age 12 and older): TAK-062 Dose 1 + Gluten-free SIGE Bar 6. Cohort 2 (Age 12-17): TAK-062 Dose 2 + Gluten-free SIGE Bar This multi-center trial will be conducted in the United States (US), Canada, United Kingdom and the European Union. The overall time to participate in this study is approximately 36 weeks.