Seminars in oncology
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Seminars in oncology · Dec 2000
ReviewTrastuzumab in combination with chemotherapy for the treatment of metastatic breast cancer.
Metastatic breast carcinoma still remains an incurable condition. The relentless search for novel agents that might prove useful for management has evolved toward monoclonal antibodies, in part because of a rapidly expanding understanding of breast cancer biology. Trastuzumab (Herceptin; Genentech, Inc, South San Francisco, CA) is a recombinant humanized monoclonal antibody against the HER-2 receptor that has shown antitumor activity as a single agent in phase I and II trials of patients with metastatic breast cancer overexpressing HER-2. ⋯ Two trials were presented at the 1999 meeting of the American Society of Clinical Oncology that evaluated this combination. One multicenter phase III trial showed clinical benefit and increased survival for patients with HER-2-overexpressing metastatic breast cancer treated with chemotherapy plus trastuzumab. A phase II trial, reviewed in this report, evaluated the efficacy and safety of weekly paclitaxel plus trastuzumab for patients with metastatic breast carcinoma, including those overexpressing and nonoverexpressing HER-2.
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HER-2 (c-erbB-2, neu) is an important prognostic and predictive factor in breast cancer. Clinical trials utilizing a humanized version of the anti-HER-2 murine monoclonal antibody 4DS, trastuzumab (Herceptin; Genentech Inc, South San Francisco, CA), have shown antitumor activity in patients with HER-2-positive metastatic breast cancer. ⋯ The Breast Cancer Intergroup has recently completed several trials evaluating new chemotherapy treatment approaches for patients with node-positive breast cancer, which form the basis for several ongoing and planned clinical trials incorporating trastuzumab. These clinical trials and the evolving role of trastuzumab-containing adjuvant systemic therapy for breast cancer will be reviewed.
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Seminars in oncology · Dec 2000
ReviewOngoing and planned trials of hormonal therapy and trastuzumab.
Studies with human breast cancer cell lines have shown a causal association between overexpression of the HER-2/neu proto-oncogene receptor and the acquisition of resistance to tamoxifen. Some clinical studies also indicate that patients with tumors showing high HER-2 levels or high levels of the circulating ectodomain of HER-2 may have a lower response to tamoxifen compared with tumors with low HER-2 levels or low circulating ectodomain. ⋯ We are conducting a phase II trial of a humanized anti-HER-2 monoclonal antibody, trastuzumab (Herceptin; Genentech, Inc, South San Francisco, CA) in combination with tamoxifen in patients with estrogen receptor-positive metastatic breast cancer. Other prospective randomized clinical trials are needed to directly evaluate the contribution of HER-2 signaling to antiestrogen resistance in vivo.
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Seminars in oncology · Dec 2000
ReviewChemotherapy sensitization by rituximab: experimental and clinical evidence.
For most lymphomas, chemotherapy is palliative because of an inability to overcome drug resistance within the lymphoma cells and attempts at overcoming specific drug resistance mechanisms, such as multidrug resistance, have had limited success. However, accumulating evidence suggests that the ability to activate apoptotic pathways may be an important determinant of chemotherapy sensitivity and presents a potentially important new therapeutic strategy. Studies have shown that distinct cellular thresholds exist for apoptosis, and it is likely that multiple developmental and environmental factors converge in a dynamic process to regulate this set point. ⋯ Monoclonal antibodies against the CD20 receptor have been shown to directly induce apoptosis and may serve to modulate the threshold for chemotherapy-induced apoptosis. Recent clinical studies of the monoclonal antibody, rituximab (Rituxan; Genentech, Inc, South San Francisco, CA and IDEC Pharmaceutical Corporation, San Diego, CA), and combination chemotherapy have produced unexpectedly high rates of response and progression-free survival, suggesting rituximab improves the efficacy of chemotherapy. Taken together, the results from in vitro and clinical studies suggest that rituximab may modulate the sensitivity of B-cell lymphomas to chemotherapy.
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Seminars in oncology · Dec 2000
ReviewNew insights into anti-HER-2 receptor monoclonal antibody research.
Abnormalities in the expression, structure, or activity of proto-oncogene products contribute to the development and maintenance of the malignant phenotype. For example, c-erbB-2 encodes the HER-2 receptor (also known as c-erbB-2 or c-neu) that is overexpressed, amplified, or both in a number of human malignancies including breast, ovarian, colon, lung, prostate, and cervical cancers. In addition to deregulation of cell-surface HER receptors, cancer cells often show excessive activation and/or nonattenuation of growth factor--inducible signaling components, as well as their downstream transcription factors. ⋯ Using in vitro models, recent studies have shown that HER-2 overexpression may not be a prerequisite for invasion of breast cancer cells, as HER-2 activation by heregulin, which binds to HER-3 or HER-4 and transphosphorylates HER in noninvasive breast cancer cells, could lead to increased motility, enhanced gelatinolytic activity, and invasion. Furthermore, these ligand-driven phenotypic changes were completely suppressed by trastuzumab, which also blocked interactions between HER-2 and HER-3 receptors in heregulin-treated breast cancer cells, and inhibited the phosphatidylinositol-3' kinase-dependent pathway, but not the mitogen-activated protein kinase pathway. These phenotypic effects of anti-HER-2 monoclonal antibody are of special interest, because they point to potential therapeutic effects of trastuzumab in inhibiting the invasion and metastasis of breast cancer with low receptor expression.