Chemotherapy of advanced breast cancer: the place of active new drugs

Mitomycin C and Vinblastine in Anthracycline-resistant Metastatic Breast Cancer: A Phase Ii Study

The purpose of this phase II study was to evaluate the clinical efficacy of mitomycin C and vinblastine in patients with anthracycline-resistant metastatic breast cancer. This single-center, non-randomized trial enrolled 39 patients. Eligible patients must have received at least three chemotherapy regimens with epirubicin or CAF and had treatment failure while on chemotherapy or within 6 months of completing therapy. Treatment consisted of mitomycin C at a starting dose of 8 mg/m2 on day 1 and vinblastine (8 mg/m2, days 1 and 28). The regimen was repeated every 6 weeks with a 20% dose escalation of both drugs after the first cycle in the absence of grade III hematologic or other toxicity. On an intent-to-treat basis, 38 patients were eligible for assessment; 9 (23.7%, 95% confidence interval 1.92-2.45%) achieved a partial response and 13 (34.2%) had stable disease. The median time to disease progression was 6.21 ±4.26 months (range, 1-15; 95% confidence interval, 4.81-7.61), and the median survival was 10.76±7.6 (range, 1-29; 95% confidence interval 8.0-13.1%). Responsive patients had a significantly better survival than those with stable and progressive disease. Treatment was well tolerated. Anemia and neutropenia (grade I-III) developed in 28.9% and 26.3% of the patients, respectively. One patient with grade III granulocytopenia developed fever and infection that required hospitalization. Moderate neurotoxicity, myalgia, constipation, diarrhea and alopecia were observed. No toxic death occurred. Mitomycin C plus vinblastine is an effective and well-tolerated regimen for anthracycline resistant cancer.

Novel systemic therapies for breast cancer

The rapid expansion in our knowledge of the molecular pathogenesis of cancer has created several opportunities for novel strategies in anti-cancer drug design and development. Recent developments have included a series of new endocrine therapies such as pure anti-oestrogens and selective oestrogen receptor modulators, and trials are in progress to determine their role in the sequence of therapies given the first-line role now occupied by the aromatase inhibitors. Novel cytotoxic drugs have been developed with an improved toxicity profile, including oral prodrugs that are activated within tumour cells, and liposomal delivery mechanisms for conventional drugs that reduce some of the systemic toxicities. There has been much success with monoclonal antibodies targeted against growth factor receptors, both as monotherapy and in enhancing the efficacy of cytotoxic drugs. A number of small molecule signal transduction inhibitors are in early stages of clinical development for breast cancer, including tyrosine-kinase inhibitors and farnesyl transferase inhibitors. Emerging pre-clinical evidence suggests that these drugs may best be used in combination with endocrine therapy. Other novel strategies that are being tested include vaccines and anti-angiogenesis drugs. As these new therapies evolve towards the clinic, the challenge to oncologists is whether their potential seen in the laboratory can be matched by further substantial improvements in clinical outcome.

Systemic treatment of metastatic breast cancer

This article reviews recent advances in the treatment of metastatic breast cancer, in particular the results of randomized controlled phase III clinical trials. These have led to the evidence-based introduction of several new drugs including aromatase inhibitors, taxanes and bisphosphonates, some of which have been shown to impact on overall survival.