A Study to Investigate the Efficacy and Safety of Rilzabrutinib in Adult Participants With Graves' Disease

This is a parallel group, Phase 2, 2-arm study to measure the treatment effect and safety of rilzabrutinib dose 1 or rilzabrutinib dose 2 in participants with Graves' disease, with and without Graves' orbitopathy, aged 18 years or older. Study details include: * Screening period (up to 4 weeks). * Treatment period (up to 16 weeks). * Follow-up period (4 weeks). The number of visits will be up to 13.

Inclusion Criteria: * Participants who have a confirmed diagnosis of Graves' disease with active hyperthyroidism, with or without active Graves' orbitopathy at the time of screening. * A subset of participants will have a diagnosis of active Graves' orbitopathy, as confirmed by ophthalmic exam at screening and a clinical activity score (CAS) ≥3 for the most severely affected eye, and associated with one or more of the following: lid retraction ≥2 mm, moderate or severe soft tissue involvement, proptosis ≥2 mm, and/or intermittent or constant diplopia. * Contraceptive use by men and women should be consistent with local regulations regarding the methods of contraception for those participating in clinical studies. Exclusion Criteria: * History of hyperthyroidism not caused by Graves' disease (eg, hyperthyroidism due to toxic multinodular goiter, autonomous thyroid nodule, acute inflammatory thyroiditis). * History of thyroid storm or at high risk of developing thyroid storm as determined by evaluating clinician. * Enlarged thyroid goiter causing upper airway obstruction and/or requiring surgical intervention during the study period. * For participant with Graves' orbitopathy, requires immediate surgical ophthalmological intervention or is planning corrective surgery/irradiation during the course of the study. * Sight threatening Graves' orbitopathy or decreased visual acuity due to optic neuropathy within the last 6 months. * Corneal decompensation unresponsive to medical management. * Onset of Graves' orbitopathy symptoms \>9 months prior to baseline. The above information is not intended to contain all considerations relevant to a patient's potential participation in a clinical trial.