In two phase II clinical trials presented at the annual meeting of the American Society of Clinical Oncology, researchers found that gemcitabine(Drug information on gemcitabine) (Gemzar) alone and in combination with docetaxel(Drug information on docetaxel) (Taxotere) was associated with a high level of activity and an acceptable toxicity profile in women with previously treated refractory metastatic breast cancer.
Standard treatment in the United States for patients with anthracycline-refractory metastatic breast cancer has been sequential single-agent therapy, often starting with taxanes—ie, docetaxel or paclitaxel(Drug information on paclitaxel) (Taxol). Data from these trials suggest that gemcitabine alone or in combination with docetaxel should be investigated as an alternative for patients who previously received anthracycline-based and in some cases taxane-based chemotherapy.
Gemzar in Taxane- or Anthracycline-Resistant Breast Cancer
In one of the trials, researchers evaluated the efficacy and tolerability of gemcitabine in 22 women with metastatic breast cancer resistant to taxane- or anthracycline-based therapy. The mean age of study participants was 55 years. All had received two or fewer previous treatment regimens for metastatic disease and developed disease progression despite either taxane- or anthracycline-based therapy. All had measurable progressive lesions with no evidence of brain metastasis.
During each 28-day treatment cycle, patients were given gemcitabine intravenously (IV) at a dose of 1,000 mg/m2 on days 1, 8, and 15. Patients with symptomatic bone lesions also received radiotherapy. At the end of every three cycles, patients were restaged and response was evaluated using World Health Organization (WHO) criteria.
The overall response rate was 23%, with one patient demonstrating a complete response and four patients, a partial response. Stable disease was achieved by 6 patients (27.2%), while 11 (50%) showed evidence of disease progression. Hematologic toxicity was manageable and did not require the use of growth factors. The main side effect was an influenza-like syndrome with fever (45.4%) and fatigue (36.3%).
"While the majority of women with metastatic breast cancer are treated initially with taxanes, many fail to respond, eventually progress, or experience dose-limiting toxicity," said Andrew D. Seidman, MD, associate attending physician, Breast Cancer Medicine Service, Memorial Sloan-Kettering Cancer Center in New York. "Developing effective drugs that have acceptable toxicity is a high priority in treating breast cancer patients, many of whom are middle-aged and lead active lives while undergoing chemotherapy. Results from this study and previously published studies suggest that gemcitabine deserves attention and further investigation in this patient population."
Multicenter Trial of Combination Therapy
In a multicenter phase II trial, researchers evaluated the efficacy and safety of the gemcitabine/docetaxel combination as second-line chemotherapy in 30 women with metastatic breast cancer who failed to respond to anthracycline-based therapy. The median age of participants was 57 years. All had metastatic breast cancer, with 23 showing evidence of visceral disease. All also had anthracycline-resistant disease. Prior to the start of the trial, 13 women had received one previous chemotherapy regimen, while 17 women had received two or more previous regimens. Moreover, 26 patients had received prior anthracycline-based chemotherapy, while 4 had received taxane-based chemotherapy (5 as adjuvant).
As part of each treatment cycle, patients were given gemcitabine (1,000 mg/m2 IV over 30 minutes on days 1 and 8) and docetaxel (80 mg/m2 IV over 1 hour on day 8). The cycle was repeated every 3 weeks, and a total of 148 cycles were administered.
The overall response rate was 60%, with two patients demonstrating a complete response and 18 patients, a partial response. The median time to disease progression was 6 months. The median overall survival after 6 months has not yet been determined. Treatment-related adverse events were mild to moderate in intensity. They included leukopenia (31%), neutropenia (33%), anemia (11%), hair loss (93%), and mucositis (7%).
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