New chemotherapeutic agents for breast cancer

Chloroquine and its analogs: a new promise of an old drug for effective and safe cancer therapies

Chloroquine (CQ), N'-(7-chloroquinolin-4-yl)-N,N-diethyl-pentane-1,4-diamine, is widely used as an effective and safe anti-malarial and anti-rheumatoid agent. CQ was discovered 1934 as "Resochin" by Andersag and co-workers at the Bayer laboratories. Ironically, CQ was initially ignored for a decade because it was considered too toxic to use in humans. CQ was "re-discovered" during World War II in the United States in the course of anti-malarial drug development. The US government-sponsored clinical trials during this period showed unequivocally that CQ has a significant therapeutic value as an anti-malarial drug. Consequently, CQ was introduced into clinical practice in 1947 for the prophylaxis treatment of malaria (Plasmodium vivax, ovale and malariae). CQ still remains the drug of choice for malaria chemotherapy because it is highly effective and well tolerated by humans. In addition, CQ is widely used as an anti-inflammatory agent for the treatment of rheumatoid arthritis, lupus erythematosus and amoebic hepatitis. More recently, CQ has been studied for its potential as an enhancing agent in cancer therapies. Accumulating lines of evidence now suggest that CQ can effectively sensitize cell-killing effects by ionizing radiation and chemotherapeutic agents in a cancer-specific manner. The lysosomotrophic property of CQ appears to be important for the increase in efficacy and specificity. Although more studies are needed, CQ may be one of the most effective and safe sensitizers for cancer therapies. Taken together, it appears that the efficacy of conventional cancer therapies can be dramatically enhanced if used in combination with CQ and its analogs.

The efficacy and selectivity of tumor cell killing by Akt inhibitors are substantially increased by chloroquine

This study was to evaluate the enhancement value of chloroquine (CQ) in cancer cell killing when used in combination with Akt inhibitors. The results showed that the combination of CQ and Akt inhibitors is much more effective than either one alone. Importantly, the CQ-mediated chemosensitization of cell killing effects by Akt inhibitors is cancer specific. In particular, when combined with 10 microM CQ, 1,3-dihydro-1-(1-((4-(6-phenyl-1H-imidazo[4,5-g]quinoxalin-7-yl)phenyl)methyl)-4-piperidinyl)-2H-benzimidazol-2-one (an Akt1 and 2 inhibitor; compound 8) killed cancer cells 10-120 times more effectively than normal cells. Thus, CQ is a very effective and cancer-specific chemosensitizer when used in combination with Akt inhibitors.

Central nervous system metastases in HER-2-overexpressing metastatic breast cancer: a treatment challenge

With improvements in diagnostic and therapeutic options and a corresponding improvement in survival, central nervous system (CNS) metastasis is becoming a more frequent diagnosis in breast cancer patients. It can be assumed that up to 30% of metastatic breast cancer (MBC) patients may experience CNS metastasis during the course of their disease. Moreover, it has been reported that patients with human epidermal growth factor receptor (HER)-2-overexpressing MBC are at a higher risk for CNS involvement. Whereas locoregional treatment modalities such as surgery, radiosurgery, and whole-brain radiotherapy still must be considered as the treatment of first choice, the armamentarium of systemic treatment modalities has been expanded by the introduction of small molecules such as the tyrosine kinase inhibitors. Rather than analyzing the risk factors for the development of CNS metastasis and reviewing the standard diagnostic and therapeutic approaches in patients with CNS involvement, this review focuses specifically on systemic treatment modalities in patients suffering from CNS metastasis from HER-2-overexpressing MBC.

Temozolomide: a milestone in neuro-oncology and beyond?

Temozolomide (Temodal, Temodar), an imidazol derivative, is a second-generation alkylating agent. The orally available prodrug with the capacity of crossing the blood-brain barrier received accelerated US FDA approval in 1999. Three pivotal Phase II trials showed modest activity in the treatment of recurrent anaplastic astrocytoma glioblastoma. In 2005, the FDA and the European Agency for the Evaluation of Medicinal Products approved temozolomide for use in newly diagnosed glioblastoma, in conjunction with radiotherapy, based on an European Organisation for Research and Treatment of Cancer/National Cancer Institute of Canada Phase III trial. The adverse events associated with temozolomide are mild-to-moderate and generally predictable; the most serious are noncumulative and reversible myelosuppression and, in particular, thrombocytopenia, which occurs in less than 5% of patients. Continuous temozolomide administration is associated with profound CD4-selective lymphocytopenia. Molecular studies have suggested that the benefit of temozolomide chemotherapy is restricted to patients whose tumors have a methylated methylguanine methyltransferase gene promotor and are thus unable to repair some of the chemotherapy-induced DNA damage. Temozolomide is under investigation for other disease entities, in particular lower-grade glioma, brain metastases and melanoma.

Evaluation of the epidoxorubicin--formaldehyde conjugate, epidoxoform, in a mouse mammary carcinoma model

This study was conducted to evaluate the toxicity and efficacy of Epidoxoform, a prodrug of the active metabolite of epidoxorubicin, in a mouse model of mammary carcinoma. A dose escalation trial established a maximal tolerated dose of 20 mg/kg given intraperitoneally (i.p.) to 6-8 week old female C3 HeJ mice. Two days following injection of 10(6) Gollin-B mouse mammary tumor cells into the mammary fat pad, Epidoxoform was given and tumor growth compared to mice treated similarly with the maximum tolerated dose of epidoxorubicin and untreated controls. In all efficacy trials, a significant difference was found for tumor volume between Epidoxoform and epidoxorubicin treated mice and controls. In mice treated with a two-dose regimen, significantly increased efficacy was also found between Epidoxoform compared to epidoxorubicin. Epidoxoform appears to be efficacious in this model of mammary carcinoma, with improved efficacy over the parent compound epidoxorubicin. Further evaluation of this analogue appears warranted.

Vinorelbine and paclitaxel as first-line chemotherapy in metastatic breast cancer

PURPOSE

To evaluate the efficacy and toxicity of a combination of vinorelbine (VNB) and paclitaxel (PTX) as first-line chemotherapy in metastatic breast carcinoma (MBC).

PATIENTS AND METHODS

Between August 1995 and August 1997, 49 patients with untreated MBC received a regimen that consisted of VNB 30 mg/m2 in a 20-minute intravenous (IV) infusion on days 1 and 8 and PTX 135 mg/m2 in a 3-hour IV infusion (starting 1 hour after VNB) on day 1. Cycles were repeated every 28 days. The median age of the patients was 52 years, and 59% of patients were postmenopausal. Median performance status was 1. Dominant sites of disease were soft tissue in 6%, bone in 29%, and viscera in 65%.

RESULTS

Objective responses were recorded in 27 of 45 assessable patients (60%; 95% confidence interval, 46% to 74%). Complete remissions occurred in three patients (7%), and partial remissions occurred in 24 patients (53%). No change was recorded in 12 patients (27%), and progressive disease occurred in six patients (13%). The median time to treatment failure was 7 months, and median survival duration was 17 months. The limiting toxicity was myelosuppression, mainly leukopenia in 49 patients (100%) (grade 1 to grade 2, four patients; grade 3, 30 patients; and grade 4, 15 patients). Neutropenia was observed in 100% of patients (grade 1 to grade 2, three patients; grade 3, 11 patients; grade 4, 35 patients). Two treatment-related deaths due to febrile neutropenia were observed in patients with massive liver involvement. Peripheral neurotoxicity developed in 33 patients (67%) (grade 1, 25 patients; grade 2, eight patients); there were no grade 3 or grade 4 episodes.

CONCLUSION

The combination of VNB-PTX showed significant activity as first-line chemotherapy for patients with MBC. Myelosuppression was the dose-limiting side effect, whereas neurotoxicity was mild to moderate.

Inhibition of tumor growth and microvascular angiogenesis by the potent angiogenesis inhibitor, TNP-470, in rats

The antiangiogenic effects of TNP-470 on the neovascularization of tumors were studied by examining ultrastructural alterations in the vasculature and interstitial fluid pressure (IFP) of tumors. Wistar rats were first inoculated subcutaneously (s.c.) with the Walker 256 carcinosarcoma cell line, then either vehicle medium or TNP-470, 30 mg/kg, was injected s.c. on day 1. A tumor growth assay, the necrotic area, and the IFP in the tumor were all measured on day 12. The antiangiogenic effects of TNP-470 were studied by scanning electron microscopic images of tumor vascular casts. TNP-470 was observed to inhibit tumor growth and increase the necrotic area significantly. In the TNP-470-treated group, the IFP in the superficial layer, defined as 2-3 mm from the tumor capsule, and in the deep layer, defined as 8-10 mm from the tumor capsule, were significantly higher than the corresponding values in the control. Moreover, vascular casts showed a significant reduction in the budding of sprouts in the superficial layer, and a decrease in the maximum diameter of the tumor vessels in the deep layer. It is possible that the higher IFP in the TNP-470-treated tumors might have prevented tumor vessel dilation. The findings of this study demonstrated that TNP-470 inhibited the budding of tumor vessel sprouts, and increased the IFP. These processes seem to act synergistically to suppress tumor angiogenesis.

Stromelysin-3 induction and interstitial collagenase repression by retinoic acid. Therapeutical implication of receptor-selective retinoids dissociating transactivation and AP-1-mediated transrepression

Human stromelysin-3 and interstitial collagenase are matrix metalloproteinases whose expression by stromal cells in several types of carcinomas has been associated with cancer progression. We compared here the regulation of the expression of both proteinases by retinoids in human fibroblasts. Physiological concentrations of retinoic acid were found to simultaneously induce stromelysin-3 and repress interstitial collagenase. In both cases, the involvement of a transcriptional mechanism was supported by run-on assays. Furthermore, in transient transfection experiments, the activity of the stromelysin-3 promoter was induced by retinoic acid through endogenous receptors acting on a DR1 retinoic acid-responsive element. The ligand-dependent activation of the receptors was also investigated by using selective synthetic retinoids, and we demonstrated that retinoic acid-retinoid X receptor heterodimers were the most potent functional units controlling both stromelysin-3 induction and interstitial collagenase repression. However, specific retinoids dissociating the transactivation and the AP-1-mediated transrepression functions of the receptors were found to repress interstitial collagenase without inducing stromelysin-3. These findings indicate that such retinoids may represent efficient inhibitors of matrix metalloproteinase expression in the treatment of human carcinomas.

TNP-470 antiangiogenic therapy for advanced murine neuroblastoma

The finding that angiogenesis plays an important role in the progression and metastasis of malignant tumors has led to the development of several antiangiogenic drugs. The authors report here an examination of the effect of the antiangiogenic agent TNP-470 on the growth, metastases, and survival of two differing murine neuroblastoma cell lines, TBJ and C1300. We found that TNP-470 significantly reduced primary tumor volumes in mice injected with either cell line. In addition, antiangiogenic therapy significantly reduced the size of axillary lymph node metastases in both groups as well as decreased the size of liver metastases in mice receiving TBJ neuroblastoma. TNP-470 treatment also improved animal survival. These data suggest that antiangiogenic therapy retards the growth of primary and metastatic murine neuroblastoma. We speculate that antiangiogenic therapy may be a useful therapeutic modality in the treatment of advanced neuroblastoma once side effects and appropriate dosage requirements are determined.

Inflammatory breast carcinoma

Inflammatory breast cancer (IBC) is a rare subtype of breast cancer traditionally associated with an extremely poor prognosis. The appearance of the effected breast can be misleading, with the incorrect diagnosis of an infective process, rather than a malignant disease, further delaying treatment. Compared with the results achieved by monotherapy with either surgery, radiotherapy or chemotherapy; multimodality treatments have achieved significant improvements in both disease-free and overall survival. The purpose of this article is to provide a comprehensive review of the current literature and highlight those areas where potential advances in the overall management of IBC have been made.