A Study of Nemtabrutinib (MK-1026) Versus Comparator (Investigator's Choice of Ibrutinib or Acalabrutinib) in First Line (1L) Chronic Lymphocytic Leukemia (CLL)/ Small Lymphocytic Lymphoma (SLL) (MK-1026-011/BELLWAVE-011)

Prior treatment

• Has gastrointestinal (GI) dysfunction that may affect drug absorption.
• Has had acquired immune deficiency syndrome (AIDS)-defining opportunistic infection in the past 12 months before screening.
• Has received any systemic anticancer therapy for CLL/SLL.
• Is currently being treated with p-glycoprotein (P-gp) substrates with a narrow therapeutic index, cytochrome P450 3A (CYP3A) strong or moderate inducers or CYP3A strong inhibitors.
• Received prior radiotherapy within 2 weeks of start of study intervention, or radiation-related toxicities, requiring corticosteroids.
• Received a live or live-attenuated vaccine within 30 days before the first dose of study intervention. Administration of killed vaccines are allowed.
• Has received an investigational agent or has used an investigational device within 4 weeks before study intervention administration.
• Participants who have not adequately recovered from major surgery or have ongoing surgical complications.

Other illness

• Has an active hepatitis B virus/ hepatitis C virus (HBV/HCV) infection.
• Has clinically significant cardiovascular disease.
• Has hypersensitivity to nemtabrutinib or contraindication to ibrutinib or acalabrutinib, or any of the excipients.
• Has history of severe bleeding disorder.
• Has known additional malignancy that is progressing or has required active treatment within the past 2 years.
• Has active infection requiring systemic therapy, including intravenous (IV) antibiotics during screening.

Other

• The main exclusion criteria include but are not limited to the following:
• Has diagnosis of Richter Transformation or active central nervous system (CNS) involvement by CLL/SLL.

• The main inclusion criteria include but are not limited to the following:
• Confirmed diagnosis of CLL/SLL and active disease clearly documented to have a need to initiate therapy.
• Has at least 1 marker of disease burden.
• Has an Eastern Cooperative Oncology Group (ECOG) performance status of 0 to 2 within 7 days before randomization.
• Has the ability to swallow and retain oral medication.
• Participants who are hepatitis B surface antigen (HBsAg) positive are eligible if they have received hepatitis B virus (HBV) antiviral therapy for at least 4 weeks and have undetectable HBV deoxyribonucleic acid (DNA) viral load before randomization.
• Participants with history of hepatitis C virus (HCV) infection are eligible if HCV ribonucleic acid (RNA) viral load is undetectable at screening.
• Participants with human immunodeficiency virus (HIV) who meet ALL eligibility criteria.