Surovatamig for Chronic Lymphocytic Leukaemia

Inclusion Criteria: * Documented diagnosis of CLL/SLL with genomic features defined by unmutated IGHV. * Treatment received and response at the end of 1L (first-line) finite therapy. * Participants with SLL (except those in CR in Phase III part) must have measurable disease (nodal or extranodal) with at least one measurable target lesion. * ECOG performance status of 0 to 2. * Adequate haematologic, liver, renal and cardiac function. * Female participants: must be either women not of childbearing potential or must use a highly effective form of contraception. * Male participants who intend to be sexually active with females of childbearing potential must agree to use barrier contraception (eg, condoms). Exclusion Criteria: * Suspected or confirmed transformation of CLL/SLL to a more aggressive form of lymphoma (ie, Richter's transformation, prolymphocytic leukaemia, or DLBCL). * Evidence of active or history of Central Nervous System (CNS) involvement by CLL/SLL. * History of or ongoing confirmed progressive multifocal leukoencephalopathy. * Participants who have any concurrent or history of malignancy. * Participants with: * Active or uncontrolled infection (including Epstein-Barr virus-EBV) requiring systemic therapy. * Participants with known history of Heamophagocytic lymphohistiocytosis (HLH). * Human Immunodeficiency Virus (HIV) infection, or participants with chronic or active infection with Hepatitis B Virus (HBV) or Hepatitis C Virus (HCV). * Major cardiac abnormalities. * Prior CLL/SLL-specific therapies. * Requires chronic immunosuppressive therapy for active autoimmune/inflammatory condition or prior allogeneic stem cell or solid organ transplant. * Major surgical procedure. * Known hypersensitivity to surovatamig or any of the excipients of the product.