A Phase 1/2 Study Of HKI-272 (Neratinib) in Combination With Trastuzumab (Herceptin) In Subjects With Advanced Breast Cancer

Inclusion Criteria:

* Pathologic diagnosis of breast cancer with current stage IIIB, IIIC or IV not curable by available therapy
* Progression following at least one Herceptin-containing cytotoxic chemotherapy regimen (neoadjuvant, adjuvant, or metastatic setting)
* HER2 positive breast cancer
* At least one measurable target lesion
* Adequate performance status
* Adequate cardiac, kidney, and liver function
* Adequate blood counts
* Willingness of all subjects who are not surgically sterile or post menopausal to use acceptable methods of birth control

Exclusion Criteria:

* More than 3 prior cytotoxic chemotherapy regimens for locally advanced or metastatic disease
* Major surgery, chemotherapy, radiotherapy, investigational agents, Herceptin or other cancer therapy within 2 weeks of treatment day 1
* Prior treatment with anthracyclines with cumulative dose of \>400 mg/m\^2
* Extensive visceral disease
* Active central nervous system metastases
* Pregnant or breast feeding women
* Significant chronic or recent acute gastrointestinal disorder with diarrhea as a major symptom
* Prior exposure to HKI-272 or other HER2 targeted agents (except Herceptin and Tykerb)
* Significant cardiac disease or dysfunction
* History of life-threatening hypersensitivity to Herceptin
* Inability or unwillingness to swallow HKI-272 capsules
* Any other cancer within 5 years with the exception of contralateral breast cancer, adequately treated cervical carcinoma in situ, or adequately treated basal or squamous cell carcinoma of the skin