A Study to Investigate Safety, Tolerability, and Pharmacokinetics of Tacabrutideg (BGB-16673) in Participants With Moderate and Severe Hepatic Impairment

The goal of this study is to understand how the body processes tacabrutideg in adults with different levels of liver function (normal, moderate impairment, and severe impairment).

General Inclusion Criteria: * Body Mass Index (BMI) between ≥ 18.0 and 40 kg/m\^2, inclusive * Generally stable health (except for hepatic impairment in hepatically impaired participants) as determined by the Investigator based on medical evaluation at Screening and Check-in, with no clinically significant findings that would interfere with study participation * Female participants of non-childbearing potential who meet any of the following criteria: surgically sterile or postmenopausal * Male participants must agree to use a condom during sexual intercourse and refrain from sperm donation for the duration of the study and for 30 days after the last dose of tacabrutideg. For nonsterile male participants with a female partner of childbearing potential, use of an additional highly effective method of contraception by the female partner is highly recommended during this period. Inclusion Criteria for Moderate and Severe Hepatic Impairment Groups: * Meets National Cancer Institute-Organ Dysfunction Working Group (NCI-ODWG) criteria for moderate or severe hepatic impairment at screening: * Moderate hepatic impairment: Total bilirubin \> 1.5 to 3 × upper limit of normal (ULN), any aspartate aminotransferase (AST) * Severe hepatic impairment: Total bilirubin \> 3 × ULN, any AST * Clinically stable hepatic disease, in the opinion of the investigator, with no clinically significant worsening of hepatic function within 4 weeks prior to dosing Inclusion Criteria for Normal Hepatic Function Group: * Normal hepatic function, including total bilirubin ≤ ULN and AST ≤ ULN * Clinical laboratory test results and physical examination findings within normal limits or judged as not clinically significant by the investigator General Exclusion Criteria: * Prior exposure to any BTK protein degraders * Underlying medical conditions (including laboratory abnormalities) other than stable hepatic impairment * History of severe bleeding disorder or history of unexplained spontaneous bleeding requiring blood transfusion or other medical or surgical intervention * Positive urine drug screen or alcohol urine/breath test/blood results at Screening or Check-in Exclusion Criteria for Moderate and Severe Hepatic Impairment Groups: * Acute hepatic disease or rapidly deteriorating hepatic function * History of liver transplantation * Previously diagnosed hepatocellular carcinoma, or history of cholestatic liver disease or biliary sepsis within the past 2 years Exclusion Criteria for Normal Hepatic Function Group: * Any known or suspected hepatic disease * Clinically significant abnormalities in liver function tests at Screening * Require ongoing use of prescription or nonprescription medications, including herbal supplements (unless the medication is not expected to interfere with the pharmacokinetics, safety, or tolerability of the study drug) Note: Other protocol defined Inclusion/Exclusion criteria may apply.