This is a multinational, multi-center, observational, prospective, longitudinal disease registry designed to collect data on participants with cold agglutinin disease (CAD) or cold agglutinin syndrome (CAS). Among them, a minimum of 30 patients with CAD treated with sutimlimab are expected to take part in the sutimlimab cohort study. Patients with CAD who have been enrolled in previous sutimlimab clinical trials (e.g., BIVV009-01/LTS16214 [NCT02502903,CAD patients], BIVV009-03/EFC16215 [NCT03347396], and BIVV009-04/EFC16216 [NCT03347422]) and who either completed or discontinued the corresponding clinical trial are eligible to participate in the registry.

Inclusion Criteria:

1. Patient aged ≥18 years
2. Patient able to understand the purpose of the study and who (or whose legally authorized representative) provided signed and dated informed consent and authorization to use protected health information in accordance with national and local subject privacy regulations
3. Patient with a diagnosis of CAD or CAS as per Investigator judgment based on the diagnosis criteria listed in study protocol

Exclusion Criteria:

1. Patient with mixed warm and cold autoimmune hemolytic anemia, or warm autoimmune hemolytic anemia
2. Patient actively participating in a CAD or CAS interventional clinical trial. After a patient completes participation in said trial, he/she may be eligible for enrollment in this registry.

All patients with CAD or CAS will be eligible, regardless of the type of CAD or CAS-specific therapy they are receiving. In addition, the Cadence registry will include a sutimlimab cohort study whose objective is to assess the safety and the effectiveness of sutimlimab in patients with CAD in a real-world setting.

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.