A Study to Evaluate Pharmacokinetics (PK) and Safety of Oral Mobocertinib in Participants With Moderate or Severe Hepatic Impairment (HI) and Normal Hepatic Function

Inclusion Criteria: Inclusion Criteria for Healthy Participants 1. Continuous non-smoker or moderate smoker (less than or equal to (\<=) 10 cigarettes/day or the equivalent) before screening. Participant must agree to consume no more than 5 cigarettes or equivalent/day from the 7 days prior to mobocertinib dosing and throughout the period of PK sample collection. 2. Body mass index (BMI) greater than or equal to (\>=) 18.0 and \<=39.0 kilogram per square meter (kg/m\^2), at screening. Participants will be matched to hepatic impaired participants by BMI (mean plus minus \[+-\] 10%) at screening. At least 50% of the participants will be required to be of BMI \>=18.0 and \<=35.0 kg/m\^2, at screening. 3. Medically healthy with no clinically significant medical history, physical examination, laboratory profiles, vital signs or electrocardiograms (ECGs), as deemed by the Investigator or designee. Has liver function tests including alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), and total bilirubin within the upper limit of normal at screening and at check-in. 4. Creatinine clearance (estimated glomerular filtration rate \[eGFR\]) \>=60 milliliter per minute per 1.73 square meter (mL/min/1.73 m\^2) at screening. Inclusion Criteria for Moderate or Severe HI Participants 1. Continuous non-smoker or moderate smoker (\<=10 cigarettes/day or the equivalent) before screening. Participant must agree to consume no more than 5 cigarettes or equivalent/day from the 7 days prior to mobocertinib dosing and throughout the period of pharmacokinetic(s) (PK) sample collection. 2. BMI \>=18.0 and \<=39.0 kg/m\^2, at screening. At least 50% of the participants will be required to be of BMI \>=18.0 and \<=35.0 kg/m\^2, at screening. 3. Aside from HI, be sufficiently healthy for study participation based upon medical history, physical examination, vital signs, ECGs, and screening clinical laboratory profiles, as deemed by the Investigator or designee. 4. Creatinine clearance (eGFR) \>=60 mL/min/1.73 m\^2 at screening. 5. Chronic HI for at least 3 months before screening, and the HI must be stable, that is, no significant changes in hepatic function in the 30 days preceding screening (or since the last visit if within 6 months before screening) and treatment with stable doses of medication. Has a score on the Child-Pugh Class at screening as follows: * Moderate HI arm, Child-Pugh Class B: \>=7 and \<=9. * Severe HI arm, Child-Pugh Class C: \>=10 and \<=15. Exclusion Criteria: 1. Positive results for COVID-19 at screening or check in. 2. Seated blood pressure is less than 90/40 millimeters of Mercury (mmHg) or greater than 150/95 mmHg at screening. 3. Seated heart rate is lower than 40 beats per minute (bpm) or higher than 99 bpm at screening. 4. Healthy participants: QTcF interval is \>=450 msec in males or \>=470 msec in females; Moderate or Severe HI participants: QTcF interval is greater than (\>) 500 msec OR has ECG findings deemed abnormal with clinical significance by the Investigator or designee at screening. 5. Unable to refrain from or anticipates the use of any medication or substance (including prescription or over-the-counter, vitamin supplements, natural or herbal supplements) for the prohibited time period. 6. Been on a diet incompatible with the on-study diet, in the opinion of the Investigator or designee, within the 30 days prior to dosing and throughout the study. 7. Donation of blood or had significant blood loss within 56 days prior to dosing. 8. Plasma donation within 7 days prior to dosing. 9. Healthy participants: Positive result at screening for human immunodeficiency virus (HIV), hepatitis B surface antigen (HBsAg), or hepatitis C virus (HCV); Moderate or Severe HI participants: Positive result at screening for HIV, HBsAg positive participants are allowed to enroll if hepatitis B virus (HBV) deoxyribonucleic acid (DNA) is below 1000 copies/milliliter (mL) in the plasma. Participants who are positive for hepatitis C virus antibodies (HCVAb) can be enrolled but must not have detectable HCV ribonucleic acid (RNA) in the plasma.