BELLWAVE-010: This study is assessing the appropriate dose level, safety and tolerability of a targeted therapy called Nemtabrutinib when given in combination with Venetoclax targeted therapy in people with relapsed or refractory, chronic lymphocytic leukaemia (CLL) or small lymphocytic lymphoma (SLL) who have had prior treatmentA Phase 3, Open-label, Randomized Study to Compare the Efficacy and Safety of Nemtabrutinib (MK-1026) Plus Venetoclax Versus Venetoclax Plus Rituximab in Participants With Relapsed/Refractory Chronic Lymphocytic Leukemia/Small Lymphocytic Lymphoma Following at Least 1 Prior Therapy

Inclusion

• Confirmed diagnosis of chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) and active disease clearly documented to initiate therapy.
• Deletion (Del) (17p) status, tumor protein 53 (TP53) mutation status, immunoglobulin heavy chain gene (IGHV) mutation status and Bruton's tyrosine kinase (BTK)-C481 mutation status results required before randomization for Part 2 participants only.
• Relapsed or refractory to at least 1 prior available therapy.
• Have 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 a life expectancy of at least 3 months.
• 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.
• Participants with adequate organ function with specimens collected within 7 days before the start of study intervention.
• If capable of producing sperm, participant agrees to eliminate Nemtabrutinib: 12 days, Venetoclax: 1 month (30 days), Rituximab (rituximab biosimilar): not applicable; abstains from penile-vaginal intercourse as their preferred and usual lifestyle; OR uses prescribed contraception.
• Participant assigned female sex at birth are eligible to participate if not pregnant or breastfeeding and are not a person of childbearing potential (POCBP) OR is a POCBP and uses a contraceptive method that is highly effective, has a negative highly sensitive pregnancy test, and abstains from breastfeeding.