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

This study will test the safety of novel sonrotoclax dosing with gradual increases of sonrotoclax dose over specified periods until the intended target daily dose is reached. The focus will be on tumor lysis syndrome (TLS) and related toxicity signals. In the first part of the study, each ramp-up dosing schedule will first be tested in a small group of approximately 5 to 6 participants to assess safety and establish if the schedule is suitable for further testing in additional participants (schedule calibration). In the second part of the study, approved ramp-up schedules will be further assessed for safety in approximately 50 participants (schedule expansion). Sonrotoclax is an experimental drug that works by blocking a protein called B-cell lymphoma-2 (BCL-2). This protein helps certain types of blood tumor cells to survive and grow. When sonrotoclax blocks Bcl-2 it slows down or stops the growth of tumor cells and helps them die. This can lead to improvements in patients with certain malignant diseases including Chronic Lymphocytic leukemia (CLL). The start of treatment by BCL2 inhibitor requires progressive ramp-up over the first weeks to avoid potential consequences of initial tumor cell breakage and the release of cell content in the bloodstream. Several ramp-up schedules have already been utilized so far, and this study aims to optimize the dosing schedule by evaluating novel ones as safe, while simpler and/or faster. Zanubrutinib is a commercialized product that works by blocking a protein called Bruton's tyrosine kinase (BTK) and controlling the activity and survival of malignant B cells. Zanubrutinib has received approval in over 65 countries/regions worldwide for the treatment of adult participants with B cell malignancies, including CLL. This study will take place at multiple centers worldwide. The overall time to participate in this study is approximately 17 months.