All participants will receive rilzabrutinib orally. The screening period is up to 28 days, followed by a treatment period of 24 weeks for Part A. Participants who complete Part A and are deemed eligible for Part B can continue in the Core Part B period followed by an Extended Part B period for up to 253 weeks.

There will be a 7-day safety follow-up period after receiving the last dose of study medication either in Part A (for those not eligible for Part B or early terminated) or Part B. In addition, each participant will be asked to attend an EOT-Core Part B visit when the last participant completes 52 weeks in Core Part B. The Extended Part B period will last for up to 253 weeks.

The study is currently in the Part B Extension segment.

Inclusion Criteria:

• Male and female patients with a confirmed diagnosis of primary wAIHA or systemic lupus erythematosus (SLE)-associated wAIHA (without other SLE-related manifestations apart from cutaneous and musculoskeletal manifestations)
• Participants who have previously failed to maintain a sustained response after treatment with corticosteroids.
• Eastern Cooperative Oncology Group (ECOG) performance status grade 2 or lower.
• Up-to-date vaccination status as per local guidelines.
• Body mass index (BMI) >17.5 and <40 kg/m2
• All contraceptive use by men and women should be consistent with local regulations regarding the methods of contraception for those participating in clinical studies.

Core Part B

• Evidence of treatment efficacy to rilzabrutinib as defined by achieving overall response during Part A.
• Completion of Part A treatment period (24 weeks). Extended Part B
• Completion of Core Part B period.

Exclusion Criteria:

• Clinically significant medical history or ongoing chronic illness that would jeopardize the safety of the participant or compromise the quality of the data derived from his or her participation in the study as determined by the Investigator.
• Participants with medical history of lymphoma, leukemia, or any malignancy within the past 5 years except for basal cell or squamous epithelial carcinomas of the skin that have been resected with no evidence of metastatic disease for the past 3 years.
• Secondary wAIHA from any cause including drugs, lymphoproliferative disorders (low-count monoclonal B-cell lymphocytosis is allowed), infectious or autoimmune disease, or active hematologic malignancies. Participants with positive antinuclear antibodies but without a definitive diagnosis of an autoimmune disease are allowed.
• Myelodysplastic syndrome.
• Uncontrolled or active HBV infection: Patients with positive HBsAg and/or HBV DNA.
• HIV infection.
• Concurrent treatment with other experimental drugs or participation in another clinical trial with any investigational drug within 30 days or 5 half-lives, whichever is greater, prior to treatment start.
• Known allergy to any of the study medications, their analogues, or excipients in the various formulations of any agent.

Part B only

• Participants who receive any therapy during Part A known to be active in wAIHA.
• Presence of unacceptable side effect(s) or toxicity associated with rilzabrutinib such that there is an unfavorable risk-benefit assessment for continued treatment with rilzabrutinib in the opinion of the Investigator and/or Sponsor.

The above information is not intended to contain all considerations relevant to a patient'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