The goal of this study is to evaluate nemtabrutinib compared with investigator's choice of ibrutinib or acalabrutinib in participants with chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL) who have not received any prior therapy. The primary hypotheses are that (1) nemtabrutinib is non-inferior to ibrutinib or acalabrutinib with respect to objective response rate (ORR) per International Workshop on Chronic Lymphocytic Leukemia (iwCLL) Criteria 2018 by blinded independent central review (BICR) and (2) nemtabrutinib is superior to ibrutinib or acalabrutinib with respect to progression free survival (PFS) per iwCLL Criteria 2018 by BICR.
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.
Has an active hepatitis B virus/ hepatitis C virus (HBV/HCV) infection.
Has gastrointestinal (GI) dysfunction that may affect drug absorption.
Has diagnosis of Richter Transformation or active central nervous system (CNS) involvement by CLL/SLL.
Has had acquired immune deficiency syndrome (AIDS)-defining opportunistic infection in the past 12 months before screening.