A Study to Evaluate the Safety and Tolerability of BMS-986403 in Participants With Relapsed and/or Refractory Chronic Lymphocytic Leukemia or Small Lymphocytic Lymphoma

Inclusion Criteria: * Participants with chronic lymphocytic leukemia (CLL) or small lymphocytic lymphoma (SLL) and high-risk features must have failed at least 2 lines of prior therapy and participants with CLL or SLL and standard risk features must have failed at least 3 lines of prior therapy * Eastern Cooperative Oncology Group (ECOG) performance status of ≤ 1 * Either currently has central vascular access or is a candidate to receive central vascular access or peripheral vascular access for leukapheresis procedure * Has recovery to Grade ≤ 1 or baseline of any non-hematologic toxicities due to previous therapy, except alopecia (any Grade acceptable) and peripheral neuropathy (Grade ≤ 2 acceptable) Exclusion Criteria: * Any condition, including active or uncontrolled infection, or the presence of laboratory abnormalities, that places the subject at unacceptable risk if they were to participate in the study * Systemic fungal, bacterial, viral, or other infection that is not controlled * Active autoimmune disease requiring immunosuppressive therapy * Progressive deep vein thrombosis or pulmonary embolism requiring treatment, but not yet on a stable anticoagulation regimen Other protocol-defined inclusion/exclusion criteria apply