Exploratory Lapatinib (Positron Emission Tomography) PET Study in Subjects With Breast Cancer

Inclusion Criteria:

* Female, aged \>/= 18 years old
* Advanced or metastatic breast cancer with overexpression of HER2
* Be able to provide written informed consent and comply with protocol requirements
* If of child-bearing potential, using adequate and medically acceptable contraception method
* Have an ECOG performance status of 0-2 and be in stable condition
* Able to lie still on the PET scanner for approx. 1.5-2 h
* Adequate hepatic and renal function
* Patent ulnar artery or collateral arterial blood vessels
* If have CNS metastases, disease must be stable
* Subjects with CNS metastases should have at least a single 1 cm diameter lesion as shown on contrast MRI

Exclusion Criteria:

* Subjects with brain metastases who have undergone prior CNS surgery
* Significant brain abnormalities, neurological disorder, psychiatric disorder or previous brain damage
* Diabetes type I
* History of HIV, hepatitis B or hepatitis C infection
* Current alcohol and/or drug abuse
* Positive pregnancy test or lactation
* Malabsorption syndrome or disease affecting gastrointestinal function that may affect intestinal absorption
* Requirement for additional concurrent anti-cancer therapy
* History of uncontrolled or symptomatic angina
* Concurrent treatment with an investigational agent or anti-cytotoxic therapy or use within 30 days or 5 half-lives
* Known hypersensitivity reaction of idiosyncrasy to drugs chemically related to lapatinib or its excipients
* Concurrent treatment with CYP3A4 inducers and inhibitors
* Unwillingness to refrain from consuming red wine, Seville oranges, grapefruit, pomelo, grapefruit hybrids and their juices from 7 days before Day 1 until collection of the final pharmacokinetic sample
* Known history of claustrophobia
* Known contraindications or likely risk of toxicity to gadlinium-based MRI contrast media
* Presence of cardiac pacemaker, other electronic device or ferromagnetic metal foreign bodies
* Any abnormality found on the MRI scan which, in the opinion of the investigator, may influence the outcome of the PET scans or affect the safety of the volunteer
* Acute or active hepatic or biliary disease
* Any medical condition or circumstance making the volunteer unsuitable for participation in the study.