Increasing the response rate to cytotoxic chemotherapy by endocrine means

Primary therapy with ECF in combination with a GnRH analog in premenopausal women with hormone receptor-positive T2–T4 breast cancer

Patients with hormone receptor-positive tumors less often show a pathological complete response (pCR) than do those with hormone receptor-negative tumors. The addition of endocrine therapies may improve the clinical benefits of primary therapies in these patients. We investigated the efficacy of the epirubicin+cisplatin+fluorouracil (ECF) as continuous infusion) regimen in association with a gonadotropin-releasing hormone (GnRH) analog in 36 premenopausal women with T2-T4a-d N0-2 M0 ER and/or PgR-positive breast cancer. Median age was 39.5 years (range 26-53). Clinical response (complete or partial) was observed in 27 out of 36 patients (75% 95% CI 57.8-87.9%) and a pCR was observed in four patients (11%). Nine (25%) patients had stable disease and no progression was observed. Twenty-one patients (58%) were submitted for breast-conserving surgery and 15 had a radical mastectomy. No baseline clinical and biological characteristics significantly correlated with response. Thirty out of 31 patients evaluable for endocrine assessment had documented ovarian suppression, which occurred after a median of 28 days (range 20-43). We conclude that the combination of ECF and a GnRH analog is associated with a high response rate in the primary treatment of breast cancer. Further studies combining chemotherapy and endocrine agents are warranted in patients with hormone receptor-positive tumors.

Effect of Vinca alkaloids on ERα levels and Estradiol-induced responses in MCF-7 cells

Vinca alkaloids (VAs) such as Vincristine, Vinblastine and Vinorelbine are antineoplastic drugs that inhibit tubulin polymerisation into microtubules, induce mitotic G2/M arrest, activate c-Jun N-terminal kinase (JNK) and induce apoptosis. Although there are many studies evaluating the effect of VAs on breast cancer patients, until now little was known about how these compounds and estradiol signaling pathways might interfere. In this report, we show for the first time that VAs decreased ERalpha protein levels in the human breast cancer cell line MCF-7; VAs induced a parallel decrease in estrogen receptor mRNA. All the VAs tested inhibited estradiol (E2) mediated transactivation at ERE-driven promoters. E2 inhibited VAs-induced AP1 stimulation in MCF-7, but this inhibition was not observed when E2 is added 24 h in advance of VAs treatment. In contrast to the reported preventing effect over taxol-mediated apoptosis, E2 did not prevent VAs-induced cell death and interestingly, addition of E2 24 hours in advance of VAs treatment resulted in an increase of the number of cells undergoing apoptosis. Similar results were observed when E2 is replaced by other proliferation signals such as EGF. These results demonstrate that in the breast cancer cell-line MCF-7, E2-induced proliferation before VAs treatment enhances the apoptotical response to VAs which might have important implications in clinica.

Fundamental research leading to improved endocrine therapy for breast cancer

Whilst endocrine therapy has a long-established role in the management of patients with advanced breast cancer, current therapies produce remission in, at best, only between 30 and 40% of cases. The most efficient use of hormonal measures therefore requires the accurate identification of individuals with hormone-responsive tumours. Oestrogen receptor measurements are useful but not fully discriminatory and additional predictive factors are required. Markers, such as specific hormonally induced proteins and mRNA, and antagonistic systems, such as epidermal growth factor receptors and cyclic AMP binding proteins are currently being evaluated. In terms of therapy, surgical manoeuvres such as adrenalectomy and hypophysectomy have already been replaced by the medical administration of anti-oestrogens, progestogens and drug regimes such as aminoglutethimide-hydrocortisone. Although castration by surgery or radiation remains the first-line treatment in premenopausal women with advanced disease, the advent of depot preparations of LHRH agonists offers the opportunity of performing medical ovariectomies which have the added advantage of being reversible. As a result of laboratory studies, more potent anti-oestrogens and more specific "suicide" aromatase inhibitors are entering into clinical practice. These can be expected to increase efficacy of treatment whilst reducing its side-effects. Research using cell-lines of human breast cancer also suggests that anti-progestins and agents capable of antagonizing steroid-induced growth factors will inhibit tumour growth. Such novel therapies potentially could make a major impact in the endocrine management of breast cancer. Lastly, although the primary management of early breast cancer predominantly involves non-hormonal modalities, clinical trials are now providing evidence of survival benefit from adjuvant endocrine therapy. The knowledge accrued from the use of newer endocrine agents in advanced cancer could therefore ultimately be relevant to the treatment of earlier stages of the disease.