This is a multinational, open label, single arm study that will evaluate the impact of early multi-immune modulation with rilzabrutinib in adult ITP patients who failed first-line treatment. The study includes a screening period (up to 8 weeks), a primary analysis period (up to 28 weeks), a long-term extension period for selected participants (28 weeks) and a 24-week follow-up period only for eligible participants.

Key Inclusion Criteria:

• Male or female participants aged 18 years and older with a documented diagnosis of primary ITP in the medical history
• Participant received at least one course of first-line therapy and had a history of response while on treatment
• Participant has loss of response, relapse, or steroid dependency

Key Exclusion Criteria:

• Participants with Secondary ITP
• Participants with Evans syndrome or history of myelodysplastic syndrome
• Participants with history of lymphoma, leukemia, or any malignancy within the past 5 years except for non-melanoma skin malignancy.
• Participants with history of solid organ transplant
• Participants with history of coagulation or bleeding disorders other than ITP, including genetic conditions, other than ITP
• Participant received advanced therapy for ITP or was splenectomized
• Pregnancy or nursing The above information is not intended to contain all considerations relevant to a participant's potential participation in a clinical trial.

Qualified researchers may request access to patient level data and related study documents including the clinical study report, study protocol with any amendments, blank case report form, statistical analysis plan, and dataset specifications. Patient level data will be anonymized and study documents will be redacted to protect the privacy of trial participants. Further details on Sanofi's data sharing criteria, eligible studies, and process for requesting access can be found at: https://vivli.org