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Whole tumor cells that secrete GM-CSF have been tested in clinical trials and have demonstrated early evidence of safety and clinical activity. The intradermal administration of these cells induces a massive infiltration of dendritic cells, which process and present tumor antigens to activate tumor-specific CD4+ and CD8+ T-cells. However, trial design flaws limit the phase III evaluation of this vaccine platform. Preclinical and clinical data suggest the development of GM-CSF-secreting tumor vaccines should be continued in combination with drugs that enhance vaccine activity by mitigating immune tolerance or augmenting costimulatory pathways of T-cell activation.

GemVax AS, a subsidiary of Pharmexa A/S, is developing GV-1001, an injectable formulation of a promiscuous MHC class II peptide derived from the telomerase reverse transcriptase catalytic subunit (hTERT), for the potential treatment of solid tumors, including pancreatic, liver and NSCLC. GV-1001 is currently undergoing phase II clinical trials for pancreatic, liver and NSCLC as well as a phase III trial for pancreatic cancer.

Breast cancers are a biologically heterogeneous group of mammary tumors with distinct natural histories and varied responses to established therapies. They have long been divided into those that are hormone sensitive [as defined by expression of the estrogen receptor alpha (ERalpha) and/or the progesterone receptor (PR)] and those that are not. Notably, only those breast cancers that express ERalpha and/or PR typically respond to hormonal therapy with tamoxifen, aromatase inhibitors, or the newer agent fulvestrant. More recently, the transmembrane tyrosine kinase receptor HER-2/neu was identified as an oncogene overexpressed by about 30% of breast cancers. These HER-2/neu-overexpressing breast cancers define a subset of breast tumors that are characteristically more aggressive, and women who develop them have a shorter survival. Trastuzumab (Herceptin), a humanized monoclonal antibody specific for HER-2/neu, has revolutionized the management of metastatic HER-2/neu-overexpressing breast cancers. As a single agent, it produces response rates similar to those of many single-agent chemotherapeutic agents active in metastatic breast cancer and has limited toxicity. Combining trastuzumab with chemotherapy can result in synergistic antitumor activity. The clear efficacy of trastuzumab against HER-2/neu-overexpressing metastatic breast cancer has led to a keen interest in testing its role in the management of early breast cancer, and multiple large clinical trials are currently in progress. This review summarizes the available clinical data on the use of trastuzumab in HER-neu-overexpressing breast cancer and briefly highlights emerging opportunities for innovative, trastuzumab-based breast cancer therapies.

Trastuzumab (Herceptin) is a therapeutic monoclonal antibody specific for the human epidermal growth factor receptor type 2 (HER2), a cell-surface tyrosine kinase receptor overexpressed by 25% to 30% of breast cancers. The drug is now regarded as one option for standard therapy in HER2-overexpressing metastatic breast cancers. It is associated with a moderate response rate as a single agent, and in combination with standard chemotherapy, can produce greater response rates and prolong the survival of women with advanced breast cancer. Its activity in metastatic breast cancer has led to active clinical trials examining its potential role in the neoadjuvant and adjuvant settings. The successful clinical development of trastuzumab provides further proof of principle that biologically targeted therapies can have a profound impact on the management of breast cancer. Here we review the clinical development of this novel agent, emphasizing the potential for therapeutic synergy when trastuzumab is combined with both standard chemotherapy and innovative molecularly targeted and biologic agents.

Advances in biotechnology and basic immunology have converged to create an unprecedented opportunity to use vaccines to harness the power of the immune system in the fight against breast cancer. Cancer vaccines have several therapeutic advantages over more traditional breast cancer treatment modalities. First, targeting the antitumor immune response to critical tumor-specific antigens defines a therapy with exquisite specificity and minimal toxicity. Second, immune-mediated tumor destruction occurs by mechanisms distinct from those underlying the efficacy of chemotherapy and hormone therapy. Thus, immunotherapy offers an approach to circumventing the intrinsic drug resistance that currently underlies therapeutic failure. Third, the phenomenon of immunologic memory endows immunotherapy with the potential for creating a durable therapeutic effect that is reactivated at the onset of disease relapse. Moreover, immunologic memory also underlies the potential future use of vaccines for the prevention of breast cancer. Early clinical trials have highlighted the promise of breast cancer vaccines, and have further defined the challenges facing translational scientists and clinical investigators. The judicious application of laboratory advances to clinical trial design should facilitate the development of immunotherapy as an additional major therapeutic modality for breast cancer, with the potential for breast cancer prevention as well as treatment.