Evaluate Severe Hepatic Impairment on Dacomitinib PK

Inclusion Criteria Participants are eligible to be included in the study only if all of the following criteria apply: 1. Male and/or female participants of non childbearing potential must be 18 to 75 years of age, inclusive, at the time of signing the informed consent document (ICD). 2. Participants who are willing and able to comply with all scheduled visits, treatment plan, laboratory tests, lifestyle considerations, and other study procedures. Weight: 3. Body mass index (BMI) of 17.5 to 40 kg/m2; and a total body weight \>50 kg (110 lb). 4. Capable of giving signed informed consent as described in Appendix 1, which includes compliance with the requirements and restrictions listed in the ICD and in this protocol. Exclusion Criteria: Participants are excluded from the study if any of the following criteria apply: 1. Any condition possibly affecting drug absorption (eg, gastrectomy). 2. Other acute or chronic medical or psychiatric condition including recent (within the past year) or active suicidal ideation or behavior or laboratory abnormality that may increase the risk associated with study participation or IP administration or may interfere with the interpretation of study results and, in the judgment of the investigator, would make the participant inappropriate for entry into this study. 3. History of or current positive results for human immunodeficiency virus (HIV). 4. Previous administration with an investigational drug within 30 days (or as determined by the local requirement) or 5 half lives preceding the first dose of IP used in this study (whichever is longer). 5. Hypersensitivity to dacomitinib or its excipients. 6. A positive urine drug test. Participants with severe hepatic impairment (Cohort 1) will be eligible to participate if their urine drug test is positive with a drug for a prescribed condition that is not expected to interfere with the PK of dacomitinib. 7. Blood donation (excluding plasma donations) of approximately 1 pint (500 mL) or more within 60 days prior to dosing. 8. History of sensitivity to heparin or heparin induced thrombocytopenia. 9. Unwilling or unable to comply with the criteria in the Lifestyle Considerations section of this protocol. 10. Investigator site staff members directly involved in the conduct of the study and their family members, site staff members otherwise supervised by the investigator, or Sponsor employees, including their family members, directly involved in the conduct of the study.