Use and abuse of taxanes in the management of metastatic breast cancer

Preexposure of MCF-7 breast cancer cell line to dexamethasone alters the cytotoxic effect of paclitaxel but not 5-fluorouracil or epirubicin chemotherapy

Purpose

Glucocorticoids (GCs) are often administered prior to any chemotherapeutics to prevent the secondary effects of anticancer agents. Glucocorticoid receptors (GRs) are expressed in several types of cancer cells, particularly in several histological types of breast cancer. Activation of GRs is not associated with any specific cellular response. Both proapoptotic and antiapoptotic responses have been observed, depending on the study or the type of breast cancer cells. Therefore, it is of relevance to investigate the possible modulation of apoptotic effect of chemotherapeutic agents when cancerous cells have previously been exposed to GCs.

Methods

In vitro cell growth was assayed by counting MCF-7 cells upon exposure to epirubicin (25 nM), 5-fluorouracil (5-FU) (15 µM), and paclitaxel (15 nM), either with or without prior exposure to the GC dexamethasone (Dex) (100 nM).

Results

Following preexposure to Dex, the antiapoptotic activity of paclitaxel was significantly reduced by 8.5% (p<0.05), but the activities of epirubicin and 5-FU remained unaltered.

Conclusion

In light of the finding that the response of MCF-7 cells pretreated with Dex was significantly reduced, we recommend that the function of GCs should be defined more precisely if they are to be used in conjunction with chemotherapy.

An Open-Label, Randomized, Parallel, Phase III Trial Evaluating the Efficacy and Safety of Polymeric Micelle-Formulated Paclitaxel Compared to Conventional Cremophor EL-Based Paclitaxel for Recurrent or Metastatic HER2-Negative Breast Cancer

Purpose

Genexol-PM is a Cremophor EL–free formulation of low-molecular-weight, non-toxic, and biodegradable polymeric micelle-bound paclitaxel. We conducted a phase III study comparing the clinical efficacy and toxicity of Genexol-PM with conventional paclitaxel (Genexol).

Materials and Methods

Patients were randomly assigned (1:1) to receive Genexol-PM 260 mg/m² or Genexol 175 mg/m² intravenously every 3 weeks. The primary outcome was the objective response rate (ORR).

Results

The study enrolled 212 patients, of whom 105 were allocated to receive Genexol-PM. The mean received dose intensity of Genexol-PM was 246.8±21.3 mg/m² (95.0%), and that of Genexol was 168.3±10.6 mg/m² (96.2%). After a median follow-up of 24.5 months (range, 0.0 to 48.7 months), the ORR of Genexol-PM was 39.1% (95% confidence interval [CI], 31.2 to 46.9) and the ORR of Genexol was 24.3% (95% CI, 17.5 to 31.1) (p_{non-inferiority}=0.021, p_superiority=0.016). The two groups did not differ significantly in overall survival (28.8 months for Genexol-PM vs. 23.8 months for Genexol; p=0.52) or progression-free survival (8.0 months for Genexol-PM vs. 6.7 months for Genexol; p=0.26). In both groups, the most common toxicities were neutropenia, with 68.6% occurrence in the Genexol-PM group versus 40.2% in the Genexol group (p < 0.01). The incidences of peripheral neuropathy of greater than grade 2 did not differ significantly between study treatments.

Conclusion

Compared with standard paclitaxel, Genexol-PM demonstrated non-inferior and even superior clinical efficacy with a manageable safety profile in patients with metastatic breast cancer.

Antiproliferative effect of dexamethasone in the MCF-7 breast cancer cell line

Glucocorticoids (GCs) are used in the treatment of cancer to induce programmed cell death in the transformed cells of the hematopoietic system and to reduce side effects. Additionally, GCs are described as an inhibitor of certain chemotherapy or radiation-induced apoptosis and also an inhibitor of cancer progression by downregulating or upregulating the expression of several genes. The present study used immunofluorescence to investigate the presence of the glucocorticoid receptor (GR) in MCF-7 cells, and the cell culture growth was determined by cell counting the number of cells following exposure to GC and/or dexamethasone (Dex). The presence and immunoreactivity of the GR were confirmed, and treatment with Dex (10⁻⁸–10⁻⁷ M) caused an inhibitory effect (30–35%) on the proliferative activity of the MCF-7 cells. This growth inhibitory effect was possibly produced by the pro-apopotic effect of Dex. Since Dex is administered systematically prior to breast cancer chemotherapy, the possible interactions between these drugs require further investigation.

Kaempferol and quercetin stimulate granulocyte-macrophage colony-stimulating factor secretion in human prostate cancer cells

Granulocyte-macrophage colony-stimulating factor (GM-CSF) holds immunotherapeutic promise in prostate cancer as it activates the host immune system. Increased production of GM-CSF by cancer cells may facilitate host immunosurveillence by the dendritic cells (DC). Here, we studied the effects of kaempferol (K) and quercetin (Q) on the production of GM-CSF in PC-3 cells. Human cytokine antibody array revealed that treatment with K or Q increased GM-CSF release by PC-3 cells. We further observed by ELISA that K and Q in a concentration-dependent manner increased GM-CSF production without affecting its mRNA levels. Inhibitors of vesicular traffic through the endoplasmic reticulum and Golgi-blocked GM-CSF secretory stimulation. A microtubule-stabilizing agent stimulated GM-CSF release, whereas tubulin and actin depolymerizers suppressed K- or Q-stimulated secretion of GM-CSF. Depletion of extracellular or intracellular calcium ion inhibited the GM-CSF secretion upregulated by both K and Q. Furthermore, we showed that K- and Q-stimulated GM-CSF production involves PLC, PKC, and MEK1/2 activation. Treating human DC with the conditioned medium of K- or Q-incubated PC-3 cells increased chemotaxis of DC, which was significantly attenuated when the conditioned medium was incubated with the neutralizing antibody against GM-CSF. Taken together, our results demonstrate that K and Q activate an immune response in the prostate cancer cells by stimulating GM-CSF production, which in turn could result in the recruitment of DCs to the tumor site.

Multicenter phase II trial of Genexol-PM, a Cremophor-free, polymeric micelle formulation of paclitaxel, in patients with metastatic breast cancer

Genexol-PM is a novel Cremophor EL-free polymeric micelle formulation of paclitaxel. This single arm, multicenter phase II study was designed to evaluate the efficacy and safety of Genexol-PM in patients with histologically confirmed metastatic breast cancer (MBC). Forty-one women received Genexol-PM by intravenous infusion at 300 mg/m2 over 3 h every 3 weeks without premedication until disease progression or intolerability. A total of 331 chemotherapy cycles were administered, with a median of 8 cycles per patient (range, 1-16). Overall response rate was 58.5% (95% CI: 43.5-72.3) with 5 complete responses and 19 partial responses. Thirty-seven patients who received Genexol-PM as a first-line therapy for their metastatic disease showed a response rate of 59.5% (95% CI: 43.5-73.7), and two responses were reported in four patients treated in the second-line setting for their metastatic disease. The median time to progression (TTP) for all patients was 9.0 months (range, 1.0-17.0+ months). Grade 3 non-hematologic toxicities included sensory peripheral neuropathy (51.2%), and myalgia (2.4%). Eight patients (19.5%) experienced hypersensitivity reactions, with grade 3 in two patients. Hematologic toxicities were grade 3 and 4 neutropenia (51.2 and 17.1%, respectively), and grade 1 and 2 thrombocytopenia (22.0%). Notably, no febrile neutropenia was observed. Genexol-PM appears a promising new paclitaxel in view of significant efficacies. Further trials with different dosing schedules, durations of delivery, or in combination with other drugs are warranted.

Phase II and pharmacological study of oral paclitaxel (Paxoral) plus ciclosporin in anthracycline-pretreated metastatic breast cancer

Paclitaxel is an important chemotherapeutic agent for breast cancer. Paclitaxel has high affinity for the P-glycoprotein (P-gp) (drug efflux pump) in the gastrointestinal tract causing low and variable oral bioavailability. Previously, we demonstrated that oral paclitaxel plus the P-gp inhibitor ciclosporin (CsA) is safe and results in adequate exposure to paclitaxel. This study evaluates the activity, toxicity and pharmacokinetics of paclitaxel combined with CsA in breast cancer patients. Patients with measurable metastatic breast cancer were given oral paclitaxel 90 mg m⁻² combined with CsA 10 mg kg⁻¹ (30 min prior to each paclitaxel administration) twice on one day, each week. Twenty-nine patients with a median age of 50 years were entered. All patients had received prior treatments, 25 had received prior anthracycline-containing chemotherapy and 19 had three or more metastatic sites. Total number of weekly administrations was 442 (median: 15/patient) and dose intensity of 97 mg m⁻² week⁻¹. Most patients needed treatment delay and 17 patients needed dose reductions. In intention to treat analysis, the overall response rate was 52%, the median time to progression was 6.5 months and overall survival was 16 months. The pharmacokinetics revealed moderate inter- and low intrapatient variability. Weekly oral paclitaxel, combined with CsA, is active in patients with advanced breast cancer.

Induction of tubulin by docetaxel is associated with p53 status in human non small cell lung cancer cell lines

Docetaxel (DOC), a member of the taxane family of anticancer drugs, binds to tubulin and produces unnaturally stable microtubules that induce cell death. DOC is used clinically alone or in combination with other compounds to treat advanced stages of cancer. We have treated the human lung cancer cell lines A549 and H1299 and human cervical cancer HeLa cells with low concentrations of DOC to characterize the response of beta-tubulin isotypes and p53 genes. The relationship between p53 function and DOC, acting through a microtubule-based mechanism, was examined. We found that after 18-hr treatment with DOC, beta-tubulin gene transcription was enhanced in p53-null H1299 cells but not in A549 cells. Also, p53 RNA was strongly induced in the A549 cells. In addition, beta-tubulin levels also increased in the H1299 cells after the DOC treatment. Further demonstrating an association of DOC treatment with p53 and beta-tubulin, inhibition of p53 expression by interference RNA in A549 cells showed increasing beta-tubulin gene expression with DOC treatment. We also selected a clone from the H1299 cells that stably expressed p53, examined the beta-tubulin expression after DOC treatment and found an inhibition of beta-tubulin induction in these p53-expressing cells. Our data suggest that the initial response of cells to DOC treatment involves p53; alternatively, in the absence of p53, tubulins may be transactivated. Selection of the DOC-resistant A549 cells showed beta-tubulin expression was increased, in contrast to the initial response to the DOC treatment. From the initial and selection responses of beta-tubulin in cancer cells, it appears that there is a p53-associated beta-tubulin expression as a result of the DOC treatment.

Survival of metastatic breast carcinoma patients over a 20-year period

BACKGROUND

The expectation of improvement in patient survival with administration of new chemotherapy agents for metastatic breast carcinoma (MBC) is not consistently supported by data from clinical trials, which are often underpowered and have not detected moderate survival advantage. The aim of this study was to evaluate the impact of new agents on prognosis of MBC patients enrolled in clinical trials of first-line chemotherapy.

METHODS

Between 1983 and 2001, 640 MBC patients were entered into 6 consecutive trials; the present analysis was limited to patients. The date of diagnosis of metastatic breast disease was used to define 5 arbitrarily chosen 3-year time cohorts, 1983-1986, 1987-1989, 1992-1994, 1995-1997, and 1998-2001. Multivariate proportion of hazard (PH) models were used to evaluate changes in overall survival (OS) and progression-free survival (PFS) over time and to detect changes associated with the use of taxanes, while adjusting for differences in baseline factors among 5 cohorts.

RESULTS

Patient characteristics were evenly distributed across the 5 cohorts. Median OS was 18 months, 17.2 months, 19.2 months, 26.1 months, and 23.6 months, respectively, in cohorts 1983-1986, 1987-1989, 1992-1994, 1995-1997, 1998-2001 (P < 0.0001). Age, performance status, relapse-free survival, type of adjuvant treatment, metastatic site, and taxane first-line chemotherapy were all associated with survival. These data failed to provide an indication of temporal trend and suggested a reduction in hazard of death in two cohorts (1995-1997 and 1998-2001) where taxane was added to first-line chemotherapy.

CONCLUSIONS

The analysis provided evidence of improvement in prognosis of MBC patients that was associated with use of modern chemotherapeutic agents independent of time.

A systematic review of taxane-containing regimens for metastatic breast cancer

We compared the results of randomised trials comparing taxane-containing chemotherapy regimens with regimens not containing a taxane in women with metastatic breast cancer. The specialised register of the Cochrane Breast Cancer Group was searched in March 2004. Eligibility was assessed and data extracted from eligible studies by two reviewers. Hazard ratios (HR) were derived for time-to-event outcomes, and a fixed-effect model was used for meta-analysis. Tumour response rates were analysed as dichotomous variables. Of 21 eligible trials, 16 had published some results and 12 data on overall survival. An estimated 2621 deaths among 3643 women suggest a significant difference in overall survival in favour of taxane-containing regimens (HR 0.93, 95% confidence interval (CI) 0.86–1.00, P=0.05). The treatment effect on survival was similar if only trials of first-line chemotherapy were included, although not statistically significant. There appeared to be an advantage for taxanes in time to progression (HR 0.92, 95% CI 0.85–0.99, P=0.02) and overall response (odds ratio (OR) 1.34, 95% CI 1.18–1.52, P<0.001). There was significant heterogeneity across the trials (P<0.001), partly because of the varying efficacy of the comparator regimens. Taxane-containing regimens improved overall survival in women with metastatic breast cancer. Taxane-containing regimens are more effective than some, but not all, nontaxane-containing regimens.

Phase II Clinical Trial of Ixabepilone (BMS-247550), an Epothilone B Analog, in Metastatic and Locally Advanced Breast Cancer

Purpose

Ixabepilone (BMS-247550) is an epothilone B analog that stabilizes microtubules and has antitumor activity in taxane-refractory patients in phase I studies. In a phase II trial, we evaluated the efficacy and safety of ixabepilone in women with metastatic and locally advanced breast cancer.

Patients and Methods

Breast cancer patients with measurable disease who had paclitaxel and/or docetaxel as prior neoadjuvant, adjuvant, or metastatic therapy were treated with ixabepilone at 6 mg/m2/d intravenously on days 1 through 5 every 3 weeks. Levels of glutamate (glu) -terminated and acetylated α-tubulin, markers of microtubule stabilization, were detected by Western blot and by immunohistochemistry in a subset of matched pre- and post-treatment tumor biopsies.

Results

Thirty-seven patients received 153 cycles of ixabepilone. The best responses were a complete response in one patient (3%), partial responses in seven patients (19%), and stable disease in 13 patients (35%). Grade 3 and 4 toxicities included neutropenia (35%), febrile neutropenia (14%), fatigue (14%), diarrhea (11%), nausea/vomiting (5%), myalgia/arthralgia (3%), and sensory neuropathy (3%). Two patients were removed from study because of prolonged grade 2 or 3 neurotoxicity, and three patients were removed from study for other grade 3 and 4 nonhematologic toxicities. Compared with baseline levels, levels of both glu-terminated and acetylated α-tubulin were increased in tumor biopsies performed after ixabepilone therapy.

Conclusion

An objective response was seen in 22% of the patients in a population who had been previously treated with a taxane. Sensory neuropathy was mild with grade 3 neurotoxicity rarely seen. Microtubule stabilization occurred in tumor biopsies after treatment with ixabepilone.

Facts and Controversies in Systemic Treatment of Metastatic Breast Cancer

The management of metastatic breast cancer remains an important and controversial issue. The systemic therapy, comprising endocrine, cytotoxic and biological agents, can be administered sequentially or in combination. Few drugs or combinations provide a significant improvement in survival and, therefore, in the great majority of cases, treatment is given with a palliative intent. With the exception of first-line therapy, for which general agreement exists, currently there is no consensual standard of care. This review will summarize the current knowledge and outline the controversial issues related to systemic therapy of metastatic breast cancer, with emphasis on treatment tailoring. The potential role of tumor molecular profile(s) in the selection of patients that could benefit the most from each strategy/agent will be discussed.