Seminars in oncology
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Seminars in oncology · Oct 2000
Biological rationale for HER2/neu (c-erbB2) as a target for monoclonal antibody therapy.
The physical characteristics of tumor antigens that would make the most ideal targets for antibody therapeutics include cell surface expression; high, stable expression levels in tumor cells; low or absent expression in normal tissues; lack of a soluble form of the antigenic target; and lack of internalization of the antigen/antibody complex. HER2/neu is a 185-kd surface membrane protein that is overexpressed in approximately 25% of human breast cancers due to amplification of the HER2 gene. Overexpression of the gene results in ligand-independent activation of HER2 kinase, causing mitogenic signal transduction and increased cell proliferation. ⋯ We propose that the efficacy of trastuzumab may be explained on the basis of its effects on signal transduction, which is independent from its immune mechanism(s) of action. Furthermore, trastuzumab is synergistic with some chemotherapeutic drugs, resulting in improved therapeutic efficacy. Thus, in the case of trastuzumab, a clear distinction may be drawn between the use of monoclonal antibodies as immuneactive agents and their use to achieve a desired cellular/biochemical activity.
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Seminars in oncology · Oct 2000
ReviewCurrent and planned clinical trials with trastuzumab (Herceptin).
Trastuzumab (Herceptin; Genentech, Inc, So. San Francisco, CA) is a high-affinity, humanized anti-HER2 antibody that has shown benefit in the therapy of patients with metastatic HER2-overexpressing breast cancer. Results from initial clinical trials of trastuzumab as a single agent or in combination with chemotherapy established important guidelines for the therapy of HER2-positive tumors, but represent an early phase of clinical development. ⋯ Combination studies are not limited to cytotoxic agents, as laboratory and clinical data have demonstrated that HER2 overexpression results in resistance to hormonal therapy. Therefore, a series of studies combining hormonal treatments with trastuzumab is being considered. Finally, the integration of trastuzumab into the adjuvant and neoadjuvant settings will be studied by United States and European cooperative groups.
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Several recent advances have led to accelerated progress in breast cancer therapy. The development of new drugs with novel mechanisms of action, such as the taxanes, or oral bioavailability, such as capecitabine, has expanded the horizons of available chemotherapy. ⋯ San Francisco, CA) represents an exciting new direction that opens doors to new concepts in antitumor therapy. This report will review the most exciting possibilities for expanding the field of breast cancer management.
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Seminars in oncology · Oct 2000
ReviewImmunotherapeutic strategies for the treatment of plasma cell malignancies.
The use of immunotherapy to treat patients with plasma cell dyscrasias (PCD) such as multiple myeloma (MM) and Waldenström's macroglobulinemia (WM) has gained enormous interest in recent years, with considerable efforts being mounted by many investigators. These efforts have included the use of serotherapy (antibody-mediated immunotherapy), vaccination strategies aimed at inducing allogeneic as well as autologous anti-MM immunity, and the use of donor lymphocyte infusions (DLIs). A number of cell surface antigens on malignant plasma cells and/or B cells in MM and/or WM patients have been proposed for use in tumor cell-targeted serotherapy, including immunoglobulin idiotype, CD19, CD20, CD38, CD54, CD138, HM1.24, and MUC1 core protein. ⋯ In addition, proposed immunization strategies aimed at inducing autologous immunity include vaccination with dendritic cells pulsed with MM antigens, MM cell-dendritic cell fusions, carrier-linked idiotype protein, catalytic subunit of telomerase, or DNA encoding for single-chain variable fragments (scFv) linked to a carrier protein gene. Whole tumor vaccination strategies are also being examined and include the use of MM cells transfected and/or stimulated with cytokines, costimulatory molecules, or CD40 ligand. Finally, potential obstacles to the use of immunotherapy, including the presence of resistance antigens on MM and WM tumor cells, are discussed.