A Study to Investigate the Safety of Novel Dose Ramp-up Schedule(s) When Initiating Sonrotoclax in Participants Treated for Blood Cancers.

Inclusion Criteria:

1. Stable Eastern Cooperative Oncology Group (ECOG) Performance Status ≤ 2.
2. Adequate organ function and no very recent transfusion or blood growth factor
3. Participants of childbearing potential must be willing to use a highly effective method of birth control and refrain from egg donation for the duration of the study and for ≥ 7 days after the last dose of sonrotoclax or 1 month after the last dose of zanubrutinib, whichever is later.

   Only for participants with Chronic Lymphocytic Leukemia (CLL):
4. Confirmed diagnosis of CLL, based on Hallek et al 2018, and requiring treatment due to certain features of their disease
5. At least 1 measurable lesion based on computed tomography (CT)/magnetic resonance imaging (MRI) and no history of prolymphocytic leukemia or Richter's transformation.

   Only for participants with Mantle cell lymphoma (MCL):
6. Historically confirmed diagnosis of MCL based on the World Health Organization 2022 classification of Haematolymphoid Tumors (WHO-HEAM5) or based on International Consensus Classification (ICC).
7. Relapsed or refractory to the last line of therapy and have received at least 1 prior line of systemic therapy. Note: A line of therapy is considered ≥ 2 consecutive cycles of a systemic anticancer regimen. Patients with prior BTKi therapy should not have progressed during treatment or relapsed within 12 months after BTKi discontinuation.
8. Measurable disease defined as ≥ 1 nodal lesion that is \> 1.5 cm in longest diameter, or ≥ 1 extranodal lesion that is \> 1 cm in longest diameter.

Exclusion Criteria:

1. Participants unable to comply with the requirements of the protocol
2. Serologic status reflecting active viral hepatitis B virus (HBV) or hepatitis C virus (HCV) infection
3. Positive HIV serology (HIVAb) status unless certain conditions are met.
4. Participants with any major surgical procedure ≤ 28 days before first dose of study treatment
5. Prior systemic treatment for the CLL
6. Uncontrolled autoimmune hemolytic anemia or immune thrombocytopenia requiring treatment
7. Prior exposure to a BCL-2 inhibitor

NOTE: Other protocol defined Inclusion/Exclusion criteria may apply.