Extension Study to Provide Adjuvant Treatment Following Neoadjuvant Treatment and Surgical Resection in Protocol TX05-03

Inclusion Criteria: * Signed written informed consent. * Females ≥ 18 years of age. * Completed neoadjuvant treatment (regardless of treatment arm) in the TX05/ Herceptin neoadjuvant study and the investigator believes the subject requires continued access to single agent trastuzumab in order to continue deriving clinical benefit. * Successfully undergone surgical resection of their primary tumor with no evidence of residual disease (as determined by local assessment) and no other adjuvant therapy, other than trastuzumab, is planned. However, subjects will be allowed to receive hormonal therapy if they have hormone receptor positive tumors. Subjects will also be allowed to receive adjuvant radiation therapy, if required by their treating physician. * Able to comply with the study protocol. * Female subjects of childbearing potential must have a negative serum pregnancy test within 14 days of first administration of study drug and agree to use effective contraception (hormonal contraceptive, intrauterine device, diaphragm with spermicide, or condom with spermicide) throughout the study period and for 7 months after last administration of study drug. Exclusion Criteria: * Breast cancer metastases or residual disease post operatively (as determined by local assessment). * History or presence of a medical condition or disease that in the investigator's opinion would place the subject at an unacceptable risk for study participation. * Lactating or pregnant female. * Women of childbearing potential who do not consent to use highly effective methods of birth control (e.g. true abstinence \[periodic abstinence {e.g. calendar ovulation, symptothermal, post-ovulation methods} and withdrawal are not acceptable methods of contraception\], sterilization, or other non-hormonal forms of contraception) during treatment and for at least 7 months after the last administration of study drug. Subjects must agree to not breast-feed while receiving study drug. * Any condition that in the opinion of the Investigator represents an obstacle for study conduct and/or represents a potential unacceptable risk for subjects.