Oncology
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Approximately 25,000 patients have been treated to date with the humanized anti-HER2 monoclonal antibody, Herceptin. This therapy has proved effective and well tolerated in patients with HER2-positive metastatic breast cancer; adverse events were generally infusion-related fever and chills of mild-to-moderate severity. Cardiotoxicity and infusion-related reactions emerged as the two main safety concerns with the use of Herceptin. ⋯ The majority occurred during or shortly after the first infusion and were characterized by respiratory symptoms. Most patients were successfully treated; a total of 33 patients continued Herceptin therapy with no recurrence of infusion reactions. Although the benefit to risk ratio of Herceptin remains favorable, physicians must be vigilant and aggressive in managing cardiotoxicity and infusion-related reactions.
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Review Comparative Study
Herceptin alone or in combination with chemotherapy in the treatment of HER2-positive metastatic breast cancer: pivotal trials.
Large pivotal phase II and III clinical trials investigated the therapeutic efficacy and safety of the humanized anti-HER2 monoclonal antibody, Herceptin, alone and in combination with standard chemotherapy, respectively, in HER2-positive metastatic breast cancer. Eligible patients were HER2 2+ and 3+ overexpressors, as determined by immunohistochemistry (IHC). Herceptin was well tolerated in both trials. ⋯ Responses in the single-agent Herceptin trial were seen exclusively in FISH-positive patients. Approximately a quarter of HER2 2+ patients test FISH positive and may therefore benefit from therapy. Numerous studies are underway or planned to evaluate other Herceptin combinations and regimens in the metastatic and adjuvant settings.
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Measurement of molecular markers predictive of response to therapy should enable more selective and effective utilization of anticancer agents. The predictive value of HER2 remains a complex and inconclusive subject. In metastatic breast cancer, HER2-positive, ER-positive patients can show responses to endocrine treatment, but experience shorter time to progression and survival than HER2-negative patients. ⋯ HER2 testing has become an integral part of the optimal management of the breast cancer patient. Best current practice in adjuvant breast cancer therapy based on the current knowledge of the potential predictive power of HER2 constitutes not denying tamoxifen to HER2-positive, ER-positive patients or CMF to HER2-positive patients. Outside of clinical trials, adequately dosed anthracycline-based chemotherapy is the current preferred adjuvant treatment option for HER2-positive patients.
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Current therapeutic strategies for primary breast cancer aim to provide improvements in outcome with minimal toxicity to the patient. However, annual relapse rates of up to 12 to 13% during the first 10 years after treatment are seen, and although toxicity has been reduced, it remains a problem in a patient population that is largely asymptomatic. Thus, there is a clear need for more effective therapies. ⋯ Herceptin is effective and well tolerated in the metastatic setting, making it an ideal candidate for use in adjuvant breast cancer therapy. This has led to the design of a number of trials that aim to provide conclusive evidence as rapidly as possible that Herceptin is well tolerated and effective in the adjuvant setting while also addressing the question of which regimen provides greatest benefit. This review describes these trials and explains how differences in practice between North America and Europe have influenced trial design.
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The taxanes and Herceptin have been shown to possess significant clinical activity in metastatic breast cancer. Preclinical testing of taxane/Herceptin combinations demonstrated additive and synergistic interactions with paclitaxel and docetaxel, respectively. In a pivotal clinical trial, combination of paclitaxel (3-weekly) and Herceptin was associated with an increased response rate compared with paclitaxel monotherapy (41% vs. 17%; p = 0.001). ⋯ The preliminary results of a trial of weekly docetaxel and Herceptin demonstrate a response rate of 54% in 13 evaluable patients. Additional European trials of Hercep- tin/taxane combinations as first- and second-line and adjuvant therapy are ongoing. The results of the studies to date indicate that regimens combining Herceptin with 3-weekly and weekly taxane are effective and well tolerated.