Chemotherapy of breast cancer: are the taxanes going to change the natural history of breast cancer?

Kinase Plasticity in Response to Vandetanib Enhances Sensitivity to Tamoxifen in Estrogen Receptor Positive Breast Cancer

Resistance to endocrine therapy (ET) is common in estrogen receptor (ER) positive breast cancer. Multiple studies have demonstrated that upregulation of MAPK signaling pathways contributes to ET resistance. Herein we show that vandetanib treatment enhances sensitivity to ET in ET-sensitive and -resistant ER+ breast cancer models. Vandetanib treatment alters the gene expression program of ER+ breast cancer cells resulting in a less proliferative and more estrogen responsive Luminal-A like character. Tyrosine kinase network reprogramming was assessed using multiplexed kinase inhibitor beads-mass spectrometry (MIB/MS) assay to identify adaptive resistance mechanisms to vandetanib treatment, including upregulation of HER2 activity. Co-treatment to inhibit HER2 with lapatinib enhanced sensitivity to vandetanib, demonstrating biologic activity of HER2 upregulation. Using a CRISPR knockout model, we demonstrate that vandetanib effects are partially mediated by RET receptor tyrosine kinase. Finally, we use our operating room-to-laboratory assay that measures drug response in individual primary tumor cells in short term cultures to demonstrate conserved gene expression changes, including increased HER2 activity signatures, in vandetanib treated cells, and identify features associated with vandetanib response. These results support future investigation of RET targeting strategies considering reprogrammed networks, such as activated HER2, in patients with ET resistant ER+ breast cancer.

Tamoxifen Response at Single Cell Resolution in Estrogen Receptor-Positive Primary Human Breast Tumors

In ER+/HER2- breast cancer, multiple measures of intra-tumor heterogeneity are associated with worse response to endocrine therapy. To investigate heterogeneity in response to treatment, we developed an operating room-to-laboratory pipeline for the collection of live human tumors and normal breast specimens immediately after surgical resection for processing into single-cell workflows for experimentation and genomic analyses. We demonstrate differences in tamoxifen response by cell type and identify distinctly responsive and resistant subpopulations within the malignant cell compartment of human tumors. Tamoxifen resistance signatures from 3 distinct resistant subpopulations are prognostic in large cohorts of ER+ breast cancer patients and enriched in endocrine therapy resistant tumors. This novel ex vivo model system now provides a foundation to define responsive and resistant sub-populations within heterogeneous tumors, to develop precise single cell-based predictors of response to therapy, and to identify genes and pathways driving resistance to therapy.

Do Steroids Matter? A Retrospective Review of Premedication for Taxane Chemotherapy and Hypersensitivity Reactions

PURPOSE

Despite the widespread use of the taxanes paclitaxel and docetaxel for a variety of cancers and their well-known association with hypersensitivity reactions (HSRs), there is still significant variation in the prescribing practices of steroids for premedication. Premedication almost always includes dexamethasone, which can be associated with multiple adverse effects if taken for extended periods of time. This study reviews the pattern of steroid premedication in patients who received paclitaxel or docetaxel at Stanford Cancer Institute between January 2010 and June 2020.

METHODS

We used an electronic query of the electronic medical record followed up with a manual review of patient charts to ask whether we could find a correlation between steroid premedication dosing and the incidence or severity of HSRs with the first taxane dose. Variables considered included steroid dose and route, dose and type of taxane, clinical cancer group, sex, and race.

RESULTS

Five thousand two hundred seventeen patients were identified as having received paclitaxel or docetaxel, and 3,181 met criteria for our analysis. There were 264 (8.3%) HSRs. In adjusted multivariate analysis, we found no correlation of HSR rate or severity among any of the variables evaluated except gynecology oncology clinic patients, who had an increased risk (hazard ratio [HR] 1.34) of HSRs overall and high-grade HSRs (HR 2.34), and female patients, who had a higher rate of HSRs overall (HR 1.26), but not high-grade HSRs.

CONCLUSION

Neither dexamethasone dose nor route correlated with subsequent HSRs. Given the potential for adverse events from repeated high-dose steroids, our findings suggest that routine use of lower doses, such as a single 10 mg dose of dexamethasone, as premedication for taxanes to prevent HSRs is preferable to the current prescribing guidelines.

Boron clusters as breast cancer therapeutics

Since the foundation of small molecule-based therapeutics over 100 years ago, their design has been dominated by organic based components. This has also been apparent in anti-cancer therapeutics in a broad range of strategies; from the older DNA chelating drugs, to the more recent molecular-targeted therapies. The main challenges facing current treatments; multidrug resistance and low therapeutic index, can potentially be alleviated by the incorporation of boron clusters. While retaining the versatility of their organic counterparts, these compounds offer a unique set of molecular interactions, which are a useful tool in targeted therapies and can improve many organic formulations with their incorporation. This review will discuss the potential of boron clusters in medicine while focusing on their activity in the breast cancer setting.

The cancer chemotherapeutic agent paclitaxel (Taxol) reduces hippocampal neurogenesis via down-regulation of vesicular zinc

Chemotherapy-induced cognitive impairment (CICI) is increasingly recognized as a major unwanted side effect of an otherwise highly valuable life-saving technology. In part, this awareness is a result of increased cancer survival rates following chemotherapy. Altered hippocampal neurogenesis may play a role in mediating CICI. In particular, zinc could act as a key regulator of this process. To test this hypothesis, we administered paclitaxel (Px) to male C57BL/6 mice for set time periods and then evaluated the effects of Px treatment on hippocampal neurogenesis and vesicular zinc. We found that vesicular zinc levels and expression of zinc transporter 3 (ZnT3) were reduced in Px-treated mice, compared to vehicle-treated mice. Moreover, Px-treated mice demonstrated a significant decrease in the number of neuroblasts present. However, no difference in the number of progenitor cells were observed. In addition, zinc supplementation by treatment with ZnCl₂ ameliorated the Px-induced decrease in hippocampal neurogenesis and cognitive impairment. These results suggest that via disruption of vesicular zinc stores in hippocampal mossy fiber terminals, chemotherapy may impinge upon one or more of the sequential stages involved in the maturation of new neurons derived via adult neurogenesis and thereby leads to the progressive cognitive decline associated with CICI.

Thiolated chitosan-modified PLA-PCL-TPGS nanoparticles for oral chemotherapy of lung cancer

Oral chemotherapy is a key step towards 'chemotherapy at home', a dream of cancer patients, which will radically change the clinical practice of chemotherapy and greatly improve the quality of life of the patients. In this research, three types of nanoparticle formulation from commercial PCL and self-synthesized d-α-tocopheryl polyethylene glycol 1000 succinate (PLA-PCL-TPGS) random copolymer were prepared in this research for oral delivery of antitumor agents, including thiolated chitosan-modified PCL nanoparticles, unmodified PLA-PCL-TPGS nanoparticles, and thiolated chitosan-modified PLA-PCL-TPGS nanoparticles. Firstly, the PLA-PCL-TPGS random copolymer was synthesized and characterized. Thiolated chitosan greatly increases its mucoadhesiveness and permeation properties, thus increasing the chances of nanoparticle uptake by the gastrointestinal mucosa and improving drug absorption. The PLA-PCL-TPGS nanoparticles were found by FESEM that they are of spherical shape and around 200 nm in diameter. The surface charge of PLA-PCL-TPGS nanoparticles was reversed from anionic to cationic after thiolated chitosan modification. The thiolated chitosan-modified PLA-PCL-TPGS nanoparticles have significantly higher level of the cell uptake than that of thiolated chitosan-modified PLGA nanoparticles and unmodified PLA-PCL-TPGS nanoparticles. In vitro cell viability studies showed advantages of the thiolated chitosan-modified PLA-PCL-TPGS nanoparticles over Taxol® in terms of cytotoxicity against A549 cells. It seems that the mucoadhesive nanoparticles can increase paclitaxel transport by opening tight junctions and bypassing the efflux pump of P-glycoprotein. In conclusion, PLA-PCL-TPGS nanoparticles modified by thiolated chitosan could enhance the cellular uptake and cytotoxicity, which revealed a potential application for oral chemotherapy of lung cancer.

Paclitaxel-based versus docetaxel-based regimens in metastatic breast cancer: a systematic review and meta-analysis of randomized controlled trials

OBJECTIVES

Docetaxel and paclitaxel show significant clinical activity in metastatic breast cancer (MBC) and have been approved for MBC by the U.S. Food and Drug Administration, but it is still unclear whether a paclitaxel-based regimen improves outcomes over a docetaxel-based regimen in patients with MBC. We therefore performed a meta-analysis of randomized controlled trials to compare the safety and efficacy of these two regimens in MBC.

METHODS

We systematically searched for randomized controlled trials that comparing paclitaxel-based with docetaxel-based regimens in patients with MBC in PubMed (up to January 2012), Embase (1980 to January 2012), and the Cochrane databases (up to January 2012). Abstracts presented at conferences (up to January 2011) were also searched. Data were extracted from the studies by two independent reviewers. The meta-analysis was performed by Stata version 12.0 software (Stata Corporation, College Station, TX, USA).

RESULTS

Seven eligible trials involving 1694 patients with MBC were selected. Our results showed that a paclitaxel-based regimen was comparable to a docetaxel-based regimen for MBC patients in terms of OS (HR: 0.87, 95% CI: 0.60-1.27, p = 0.48), PFS (HR: 0.76, 95% CI: 0.58-1.00, p = 0.052), TTP (HR: 1.13, 95% CI: 0.81-1.58, p = 0.46), and ORR (RR: 1.01, 95% CI: 0.88-1.15, p = 0.92), but fewer grade 3 or 4 adverse events including anemia (RR: 0.64, 95% CI: 0.44-0.94, p = 0.023), neutropenia (RR: 0.74, 95% CI: 0.58-0.93, p = 0.011), febrile neutropenia (RR: 0.38, 95% CI: 0.15-0.96, p = 0.041), thrombopenia (RR: 0.62, 95% CI: 0.41-0.96, p = 0.033), mucositis (RR: 0.082, 95% CI: 0.025-0.27, p < 0.001), diarrhea (RR: 0.19, 95% CI: 0.081-0.47, p < 0.001) and fatigue (RR: 0.43, 95% CI: 0.20-0.96, p = 0.039) were observed in the paclitaxel-based regimen. However, limitations of our study needed to be considered when interpreting these results: our study was a meta-analysis of published data, and there was significant heterogeneity among included trials. Potential publication bias might also exist.

CONCLUSION

The present systematic review and meta-analysis demonstrates that both taxane-based regimens have comparable efficacy for patients with MBC, and the paclitaxel-based regimen is associated with less toxicity and better tolerability, especially in older patients and when used in weekly regimens.

Taxane therapy for early stage breast cancer

Breast cancer is the most frequent cancer of women in developed countries. Systemic adjuvant chemotherapy has dramatically improved the outcome of patients treated for early stage invasive breast cancer. Among novel chemotherapeutic agents, the taxanes have emerged as the most powerful compounds since anthracycline regimens. Two taxanes are available (paclitaxel and docetaxel) and they share some characteristics, while having a number of significant differences, both in terms of preclinical and pharmacokinetic profiles and, most importantly, clinical consequences. In clinical practice, the taxanes are now standard therapy in metastatic breast cancer. Their role as monochemotherapy or in combination with anthracyclines in advanced breast cancer has suggested their potential therapeutic impact in the treatment of patients with early breast cancer. Available results in the adjuvant and neoadjuvant setting demonstrate that taxanes, used in combination with other chemotherapeutic agents or trastuzumab, or in sequential therapy, possess the capability to induce significant improvements, in particular in terms of survival, confirming the positive impact of taxanes on the natural history of breast cancer.

Plant phenolics in the prevention and treatment of cancer

Epidemiological studies indicate that populations consuming high levels of plant derived foods have low incidence rates of various cancers. Recent findings implicate a variety of phytochemicals, including phenolics, in these anticancer properties. Both monophenolic and polyphenolic compounds from a large variety of plant foods, spices and beverages have been shown to inhibit or attenuate the initiation, progression and spread of cancers in cells in vitro and in animals in vivo. The cellular mechanisms that phenolics modulate to elicit these anticancer effects are multi-faceted and include regulation of growth factor-receptor interactions and cell signaling cascades, including kinases and transcription factors, that determine the expression of genes involved in cell cycle arrest, cell survival and apoptosis or programmed cell death. A major focus has been the inhibitory effects of phenolics on the stress-activated NF-KB and AP-1 signal cascades in cancer cells which are regarded as major therapeutic targets. Phenolics can enhance the body's immune system to recognize and destroy cancer cells as well as inhibiting the development of new blood vessels (angiogenesis) that is necessary for tumour growth. They also attenuate adhesiveness and invasiveness of cancer cells thereby reducing their metastatic potential. Augmentation of the efficacy ofstandard chemo- and radiotherapeutic treatment regimes and the prevention of resistance to these agents is another important effect of plant phenolics that warrants further research. Plant phenolics appear to have both preventative and treatment potential in combating cancer and warrant further, in-depth research. It is interesting that these effects of plant phenolics on cancer inhibition resemble effects reported for specific fatty acids (omega-3 PUFA, conjugated linoleic acids). Although phenolic effects in cells in vitro and in animal models are generally positive, observations from the less numerous human interventions are less clear. This is surprising given the positive epidemiological data and may relate to mixed diets and synergistic interactions between compounds or the bioavailability of individual compounds. Much of the work in vitro with phenolic compounds has utilized concentrations higher than the amount that can be obtained from the diet suggesting a role of fortified, functional foods in cancer suppression.

Improved biochemical strategies for targeted delivery of taxoids

Paclitaxel (Taxol) and docetaxel (Taxotere) are very important anti-tumor drugs in clinical use for cancer. However, their clinical utility is limited due to systemic toxicity, low solubility and inactivity against drug resistant tumors. To improve chemotherapeutic levels of these drugs, it would be highly desirable to design strategies which bypass the above limitations. In this respect various prodrug and drug targeting strategies have been envisioned either to improve oral bioavailability or tumor specific delivery of taxoids. Abnormal properties of cancer cells with respect to normal cells have guided in designing of these protocols. This review article records the designed biochemical strategies and their biological efficacies as potential taxoid chemotherapeutics.

Phase III trial comparing three doses of docetaxel for second-line treatment of advanced breast cancer

PURPOSE

To evaluate whether a relationship exists between docetaxel dose and clinical response in the treatment of patients with advanced breast cancer.

PATIENTS AND METHODS

Patients whose cancer had progressed after one prior chemotherapy regimen for advanced breast cancer or had recurred during or within 6 months of adjuvant chemotherapy were randomly assigned to docetaxel 60, 75, or 100 mg/m2 intravenously every 3 weeks.

RESULTS

Five hundred twenty-seven patients were randomly assigned (intent to treat [ITT]), and 524 were assessable for toxicity. In the population assessable for efficacy (n = 407), logistic regression analysis showed that increasing docetaxel dose was significantly associated with higher response rate (P = .007) and improved time to progression (TTP; P = .014). In the ITT analysis, a significant dose-response relationship was observed for tumor response (P = .026) but not for TTP (P = .067). The incidences of most hematologic and nonhematologic toxicities were related to increasing dose, with grade 3 to 4 neutropenia occurring in 76.4%, 83.7%, and 93.4% and febrile neutropenia occurring in 4.7%, 7.4%, and 14.1% of patients administered the 60, 75, and 100 mg/m2 doses, respectively. One death was considered treatment related.

CONCLUSION

A relationship between increasing dose of docetaxel and increased tumor response was observed across the dose range of 60 to 100 mg/m2 every 3 weeks. Toxicities were related to increasing dose. Depending on the therapy goal, any of the doses studied may be appropriate for second-line treatment of advanced breast cancer.

Phase II Trial of a Novel Paclitaxel Schedule As Single-Agent, First-Line Therapy for HER-2/neu-Negative Metastatic Breast Cancer: A Community-Based Study

PURPOSE

To determine the response rate (RR), progression-free survival (PFS), and toxicity in patients with HER-2/neu-negative metastatic breast cancer treated with first-line paclitaxel in a de-escalating dosing schedule.

PATIENTS AND METHODS

Between August 1999 and December 2000, 73 patients were enrolled. Paclitaxel was administered on day 1 (175 mg/m(2)) and on days 8 and 15 (80 mg/m(2) each) in each 4-week cycle (1 week of rest). Doses were de-escalated with the aim of reducing toxicity. An Eastern Cooperative Oncology Group performance status of 0, 1, or 2 was found in 55%, 41%, and 4% of patients, respectively. Median age was 59 years (range, 38 to 84 years), and 86% of patients had received prior surgery; 60%, adjuvant chemotherapy; and 59%, radiation therapy.

RESULTS

Based on an intention-to-treat analysis (N = 73), there were five patients with a complete response (6.8%), 16 with a partial response (21.9%), 17 with stable disease (23.3%), and 23 with progressive disease (31.5%) for an RR of 28.7%. Twelve patients (16.4%) were not assessable for response due to toxicity (seven patients, mainly neuropathy), withdrawal of consent (two patients), early death (two patients), or noncompliance (one patient). Median PFS was 6.5 months (range, < 1 to 36.1 months), median survival was 22.8 months (range, < 1 to 36.1 months), and median duration of response was 8.8 months (range, 3.0 to 31.8 months). Patients (n = 72) were evaluated for toxicity. Grade 3 to 4 treatment-related toxicities occurring in more than 5% of patients included neutropenia (22.2%), neuropathy (18.1%), fatigue (6.9%), and leukopenia (5.6%).

CONCLUSION

In a unique de-escalating schedule, this study of single-agent paclitaxel produced a response rate similar to other single-agent paclitaxel schedules, in first-line therapy for metastatic breast cancer, published in the literature. However, this schedule is not recommended for the therapy of metastatic breast cancer because of the higher rate of toxicity.

Controversies in breast cancer: adjuvant and neoadjuvant therapy

Initial randomised studies of chemotherapy and endocrine therapy showed that systemic treatments had a substantial impact on the survival of women with early breast cancer. The original assumption was that the efficacy of these treatments was limited to those patients presenting with more adverse prognostic features. Subsequently, meta-analyses of randomised trials revealed that the benefits of chemotherapy and endocrine therapy are not mutually exclusive and extend to all the prognostic subgroups. However, the absolute benefit varies according to baseline characteristics such as tumour stage and other biological factors. Over the last 10 years, considerable progress has been made with the introduction of new drugs into the adjuvant and neoadjuvant treatment of women with breast cancer. Taxanes and third-generation aromatase inhibitors are providing proof of additional benefits compared with standard reference treatments. In parallel, research on the biology of breast cancer is establishing novel prognostic and predictive factors, which may allow better treatment tailoring. Currently, however, women with early breast cancer and their doctors face the difficult task of making therapeutic decisions often based on early results from positive studies. In a disease where follow up is crucial to fully assess the benefit and long-term toxicities of an intervention, current knowledge leaves unanswered questions that generate debate and controversy. This review will summarise recent results from randomised trials of adjuvant and neoadjuvant therapy in women with early breast cancer and focus on the current controversies.

Synthesis and Biological Evaluation ofN-(Arylsulfanyl)carbonyl Analogues of Paclitaxel (Taxol)

Four new N-(arylsufanyl)carbonyl paclitaxel analogues (2a-d) were prepared from 7-(triethylsilyl)-protected baccatin III (5). Their cytotoxicities against human ovarian (A2780) and prostate cancer (PC3) cell lines, as well as their tubulin-assembly activities, were determined. In these assays, the new compounds showed rather weak activities, one two orders of magnitude below those of paclitaxel (taxol; 1). The known 3'-N-[(thiophen-2-yl)carbonyl] paclitaxel analogue 3 was also prepared. As previously reported, 3 exhibited strongly improved cytotoxicities and tubulin-assembly activities as compared to paclitaxel (1).

Docetaxel in the treatment of breast cancer: current experience and future prospects

It has become clear over the past 10 years that docetaxel, a semisynthetic taxoid antineoplastic agent, is among the most promising compounds to have been developed in the 1990s for the treatment of breast cancer. Data indicate that this drug became standard therapy in the treatment of patients with metastatic disease who have failed anthracycline treatment, and secondarily showed very encouraging results in the first-line metastatic setting either in monochemotherapy or when docetaxel was combined with an anthracycline. More recently, docetaxel also became one of the standard therapies in the adjuvant and neoadjuvant settings, and a promising partner for novel biologic therapies. Current research is further exploring the effect of docetaxel on outcome of early breast cancer in order to fully determine the extent that this chemotherapeutic agent will change the natural history of breast cancer.

Randomized Phase III Study of Docetaxel Compared With Paclitaxel in Metastatic Breast Cancer

Purpose

This randomized, controlled, multicenter, open-label, phase III study compared docetaxel versus paclitaxel in patients with advanced breast cancer that had progressed after an anthracycline-containing chemotherapy regimen.

Patients and Methods

Patients (n = 449) were randomly assigned to receive either docetaxel 100 mg/m2(n = 225) or paclitaxel 175 mg/m2(n = 224) on day 1, every 21 days until tumor progression, unacceptable toxicity, or withdrawal of consent.

Results

In the intent-to-treat population, both the median overall survival (OS, 15.4 v 12.7 months; hazard ratio [HR], 1.41; 95% CI, 1.15 to 1.73; P = .03) and the median time to progression (TTP, 5.7 months v 3.6 months; HR, 1.64; 95% CI, 1.33 to 2.02; P < .0001) for docetaxel were significantly longer than for paclitaxel, and the overall response rate (ORR, 32% v 25%; P = .10) was higher for docetaxel. These results were confirmed by multivariate analyses. The incidence of treatment-related hematologic and nonhematologic toxicities was greater for docetaxel than for paclitaxel; however, quality-of-life scores were not statistically different between treatment groups over time.

Conclusion

Docetaxel was superior to paclitaxel in terms of OS and TTP. ORR was higher for docetaxel. Hematologic and nonhematologic toxicities occurred more frequently in the docetaxel group. The global quality-of-life scores were similar for both agents over time.

A monoclonal antibody that binds anionic phospholipids on tumor blood vessels enhances the antitumor effect of docetaxel on human breast tumors in mice

Anionic phospholipids, principally phosphatidylserine, become exposed on the external surface of viable vascular endothelial cells in tumors, providing an excellent marker for tumor vascular targeting. We recently raised an IgG monoclonal antibody, 3G4, which binds to anionic phospholipids in a beta2-glycoprotein I-dependent manner. It inhibited tumor growth in a variety of rodent tumor models by stimulating antibody-dependent cellular cytotoxicity toward tumor vessels. In the present study, we tested the hypothesis that docetaxel, which is known to have antivascular effects on tumors, might induce exposure of anionic phospholipids on tumor vasculature and, thus, enhance the antitumor activity of 3G4. Treatment of human umbilical vascular endothelial cells with subtoxic concentrations of docetaxel (20 pmol/L) in vitro caused anionic phospholipids to be externalized without inducing apoptosis. Docetaxel treatment of mice increased the percentage of tumor vessels that expose anionic phospholipids from 35% to 60%. No induction of phosphatidylserine was observed on vessels in normal tissues even after systemic treatment with docetaxel. Treatment of mice bearing orthotopic MDA-MB-435 human breast tumors with 3G4 plus docetaxel inhibited tumor growth by 93%. Treatment of mice bearing disseminated MDA-MB-435 tumors with 3G4 plus docetaxel reduced the average number of tumor colonies in the lungs by 93% and half the animals did not develop tumors. In both tumor models, the antitumor effect of the combination was statistically superior (P < 0.01) to that of docetaxel or 3G4 alone. Combination therapy reduced the tumor vessel density and plasma volume in tumors to a greater extent than did the individual drugs. The combination therapy was no more toxic to the mice than was docetaxel alone. These results indicate that, as an adjuvant therapy, 3G4 could enhance the therapeutic efficacy of docetaxel in breast cancer patients.

A multicentre, randomised phase II study of weekly or 3-weekly docetaxel in patients with metastatic breast cancer

BACKGROUND

A phase II randomised trial was conducted to evaluate the tolerability and activity of weekly or 3-weekly docetaxel in patients with metastatic breast cancer.

PATIENTS AND METHODS

Eighty-three patients with histologically proven metastatic breast cancer were randomised to receive either docetaxel 40 mg/m2 weekly for 6 consecutive weeks followed by 2 weeks without treatment (n = 41), or docetaxel 100 mg/m2 on day 1 every 3 weeks (n = 42).

RESULTS

The incidence of all grade 3-4 adverse events was higher in the 3-weekly group than in the weekly group (96 versus 44), and the number of patients with grade 3-4 adverse events was also greater in the 3-weekly group (31 versus 20). Analysis of individual adverse events tended to favour the weekly regimen. Intent-to-treat overall response rate was 34% and 33% in the weekly and 3-weekly groups, respectively. Median time to progression was 5.7 and 5.3 months after weekly and 3-weekly docetaxel, respectively, and median time to treatment failure was 4.1 and 4.9 months, respectively.

CONCLUSION

Weekly docetaxel is an active regimen in metastatic breast cancer with comparable efficacy to 3 weekly docetaxel. Although both schedules were well tolerated, weekly docetaxel appears to have a more favourable toxicity profile.

Evidence-based use of neoadjuvant taxane in operable and inoperable breast cancer

Neoadjuvant chemotherapy (NC) is standard therapy for patients with locally advanced breast cancer and is increasingly used for early-stage operable disease. The aim of NC is a pathological complete response (pCR) in the breast and axillary lymph nodes, which is the best predictor of improved outcome and prolonged survival. The taxanes docetaxel and paclitaxel are potent agents in breast cancer management, with promising single-agent activity and acceptable tolerability in the neoadjuvant setting. In this review of the taxanes as NC for operable and inoperable breast cancer, we include all fully published Phase II-III studies enrolling > or =30 patients. Current evidence suggests that the sequential administration of taxane- and anthracycline-based therapy may be superior to concomitant administration. Indeed, until the recent Phase III Aberdeen study (n = 162), it was uncertain whether NC could prolong survival. In this study, sequential docetaxel after anthracycline-based NC significantly enhanced the clinical response rate and pathological complete response, and yielded a significant 3-year survival advantage, versus anthracycline-based NC alone. Recently, the Phase III National Surgical Adjuvant Breast and Bowel Project (NSABP) trial B27 trial (n = 2411) showed that sequential docetaxel after doxorubicin-cyclophosphamide significantly increased both clinical and pathological response rates for operable breast cancer, with the benefit evident in both estrogen receptor-positive and estrogen receptor-negative patients. This apparent superiority of a sequential anthracycline-taxane regimen is limited to docetaxel, with no similar Phase III trials of paclitaxel versus a non-taxane-based comparator having been conducted to date. In conclusion, current evidence supports the inclusion of a taxane in NC schedules for patients with large and locally advanced breast cancer.

The bioactive Taxol conformation on beta-tubulin: experimental evidence from highly active constrained analogs

The important anticancer drug Taxol (paclitaxel) binds to tubulin in a stoichiometric ratio and promotes its assembly into microtubules. The conformation of microtubule-bound drug has been the subject of intense study, and various suggestions have been made. In this work we present experimental and theoretical evidence that Taxol adopts a T-shaped conformation when it is bound to tubulin.

All-trans retinoic acid potentiates Taxotere-induced cell death mediated by Jun N-terminal kinase in breast cancer cells

Taxotere is a cytotoxin effective in treating breast and prostate cancer. It stabilizes microtubules and causes catastrophic cell cycle arrest in G2/M. Taxanes also initiate apoptosis by activating signal pathways, such as the jun N-terminal kinase (JNK) pathway. Strategies aimed at potentiating cell death signaling may improve their efficacy while lessening the potential side effects. We reported that all-trans retinoic acid (ATRA) potentiated taxane-mediated cell death. Here we investigated whether ATRA potentiates cell death signaling through the JNK pathway. Activation of JNK by Taxotere 0.01, 0.1 and 1.0 microM was observed at 24 h in adherent cells and increased at 48 h. Taxotere 0.001 microM-induced JNK activation started after 48 h and increased at 72 h. The timing and intensity of PARP cleavage was similar to that of JNK activation. JNK activation and PARP cleavage induced by 30 nM Taxotere at 48 h were reversed by curcumin, PD169316 and SP600125, JNK inhibitors in order of progressive specificity. None of these inhibitors had an effect on p38 or ERK phosphorylation. All three inhibitors reversed Taxotere-induced phosphorylation of Bcl-2. ATRA induced JNK activation at 24, 48 and 72 h. Incubating cells with ATRA 0.01 microM for 3 days prior to Taxotere treatment potentiated Taxotere-induced JNK activation 24 and 48 h later, an effect sustained for 72 h. Cytotoxicities from 3-day ATRA 0.01 microM incubations were synergistic with subsequent 1-h Taxotere 0.01, 0.1 and 1.0 microM incubations in breast cancer cell lines MCF-7 and MDA-MB-231 and in prostate cancer cell lines LNCaP and PC-3, and additive in breast cancer cell line SK-Br-3. These data demonstrate the potentiation of Taxotere-induced cell death by ATRA pretreatment in breast and prostate cancer cells, and support a mechanism through accentuated and sustained JNK activation.

Docetaxel plus epirubicin is a highly active, well-tolerated, first-line chemotherapy for metastatic breast cancer: results of a large, multicentre phase II study

PURPOSE

In this multicentre phase II study, the efficacy and safety profile of the combination of docetaxel and epirubicin as first-line chemotherapy for metastatic breast cancer (MBC) were evaluated.

METHODS

Epirubicin (75 mg/m(2)) and docetaxel (75 mg/m(2)) were given intravenously once every 3 weeks for six cycles to 133 patients with MBC.

RESULTS

The overall clinical response rate was 67% (complete and partial responses were 23% and 44%, respectively). The median time to progression was 10.8 months (95% CI 9.7-12.6) and the median overall survival was 19.5 months. Granulocyte colony-stimulating factor support was administered to 32% of patients and in 22% of cycles. Grade 3/4 neutropenia occurred in 35% of patients and febrile neutropenia in 19%. The most frequent grade 3/4 non-haematological toxicities (as percent of patients) were asthenia (6%), vomiting (5%) and nausea (5%). No patients developed congestive heart failure.

CONCLUSIONS

The combination of docetaxel and epirubicin was highly active as first-line treatment for MBC and showed a manageable toxicity profile.

Population-based pharmacoeconomic model for adopting capecitabine/docetaxel combination treatment for anthracycline-pretreated metastatic breast cancer

PURPOSE

To model the cost-effectiveness of adopting capecitabine/docetaxel combination therapy in place of single-agent taxane therapy for women in the province of Ontario, Canada, receiving treatment for anthracycline-pretreated metastatic breast cancer.

METHODS

Clinical effectiveness and economic data were combined in a population model, from the perspective of a universal health care system. Estimates of clinical effectiveness and medical resource utilization were derived prospectively during a phase III randomized controlled trial comparing single-agent docetaxel with capecitabine/docetaxel combination therapy. Population data were obtained from the Cancer Care Ontario Registry and provincial prescription claims data.

RESULTS

During 1999-2000, 542 patients were eligible for taxane monotherapy. As capecitabine/docetaxel treatment confers a median 3-month survival benefit compared with docetaxel monotherapy, the projected survival gain in these patients was 136 life-years. The results of the cost-effectiveness analysis demonstrate that the survival benefit provided by the addition of capecitabine to single-agent docetaxel is afforded at a small incremental cost of Canadian $3,691 per life-year gained. Hospitalization costs for treatment of adverse events were less for patients receiving capecitabine/docetaxel combination therapy than for those receiving docetaxel monotherapy. The results were robust for adjustments in treatment costs and adverse effects costs.

CONCLUSION

Due to its 3-month survival gain and small incremental treatment cost, capecitabine/docetaxel is judged to be a highly cost-effective treatment in anthracycline-pretreated advanced breast cancer. From the perspective of the Ontario health care system, the addition of capecitabine to docetaxel in this patient population is a clinically appropriate and economically acceptable treatment strategy.

Decreased response to paclitaxel versus docetaxel in HER-2/neu transfected human breast cancer cells

Taxanes are effective in the treatment of metastatic breast cancer. Docetaxel has been shown to be more potent than paclitaxel in inducing bcl-2 phosphorylation and apoptosis and is clinically active in some paclitaxel-resistant breast tumors. HER-2/neu overexpression has been shown to correlate with resistance to hormonal therapy as well as chemotherapy. Using a HER-2/neu transfected MCF-7 human breast cancer cell line, we investigated the role of HER-2/neu overexpression on resistance to paclitaxel and docetaxel treatment. A control vector transfected MCF-7 human breast cancer cell line (MCF/neo) and a HER-2/neu transfected MCF-7 line (MCF/18) were treated with various concentrations of docetaxel or paclitaxel. Cell number was assessed using the MTT tetrazolium dye assay. In the control vector transfected MCF/neo cell line, paclitaxel and docetaxel gave similar dose-dependent growth inhibition ( p = 0.175). In HER-2/neu transfected MCF/18 cells, docetaxel treatment resulted in a dose-dependent inhibition similar to that seen in MCF/neo cells. Paclitaxel, however, gave significantly less growth inhibition than docetaxel in the HER-2/neu overexpressing MCF/18 cells (p = 0.0003). These data suggest that HER-2/neu overexpression may contribute to paclitaxel resistance. In contrast, the cytotoxic effects of docetaxel in these breast carcinoma cells are not affected by HER-2/neu expression. Therefore, docetaxel may be the preferred taxane therapy in HER-2/neu overexpressing breast tumors.

Capecitabine named-patient programme for patients with advanced breast cancer. the UK experience

Following the encouraging results achieved with the oral fluoropyrimidine capecitabine in clinical trials, a named patient programme was initiated in the UK, through which patients with advanced breast cancer were prescribed capecitabine monotherapy. In this programme, patients were treated with the standard dose of oral capecitabine (1250 mg/m(2) twice daily on days 1-14 of a 21-day treatment cycle). Efficacy and safety data were collected and analysed from 102 patients receiving outpatient treatment with capecitabine. All patients had previously received chemotherapy and for the majority (75%) this was in the metastatic setting. In total, 482 treatment cycles were administered, with a median of 4.5 treatment cycles (range 1-22) per patient. Tumour responses were observed in 20 patients (20%), with an additional 47 patients (46%) achieving disease stabilisation. The median time to disease progression was 4.1 months and median overall survival was 7.7 months. The most common treatment-related adverse events were palmar-plantar erythrodysaesthesia (PPE) (36%) and gastrointestinal toxicities (diarrhoea (33%) and nausea (24%)). Dose reductions due to adverse events were required in 33% of patients, but capecitabine was administered without a dose reduction for 90% of cycles. The results achieved with capecitabine in this named-patient programme confirm that, under 'real practice' conditions, capecitabine is active and well tolerated in patients with advanced breast cancer.

Neoadjuvant docetaxel in breast cancer: 3-year survival results from the Aberdeen trial

Over the past 30 years there has been an increased use of neoadjuvant (or primary) chemotherapy for treating patients with breast cancer. However, while it is clear that chemotherapy given in the adjuvant setting after surgery does prolong patients' overall and disease-free survival, the evidence that chemotherapy in the neoadjuvant setting also increases survival remains unproven. In the Aberdeen study, 162 patients with large and locally advanced breast cancer underwent 4 cycles of CVAP (cyclophosphamide/vincristine/doxorubicin/prednisone) primary chemotherapy. Patients with a complete or partial response were then randomized to either 4 further cycles of CVAP or 4 cycles of docetaxel (100 mg/m2). It was shown that the addition of sequential docetaxel (100 mg/m2) to CVAP neoadjuvant chemotherapy resulted in a significantly enhanced clinical response rate (94% vs. 64%) and a substantially increased complete histopathological response rate (34% vs. 16%) when compared to patients receiving CVAP alone. Furthermore, patients receiving docetaxel had an increased breast conservation rate (67% vs. 48%) and an increased survival at a median follow-up of 3 years. It is important to note that this was a small study, and the survival results should be interpreted with caution. The results are encouraging, however, and further studies are urgently required.

Which dosing scheme is suitable for the taxanes? An in vitro model

The discovery and development of the taxane class of antitumor compounds represent significant advances in the treatment of patients with a variety of malignancies. These drugs are effectively used in the treatment of breast cancer. In this study we evaluated the efficacy of fractionated usage of both paclitaxel and docetaxel as a single agent in the breast cancer cell line MCF-7. It has been shown that the cytotoxic effect of paclitaxel was increased when the divided IC50 concentrations were used sequentially and in contrast to paclitaxel, cytotoxic effect of docetaxel was decreased with the same schema and the single dose of IC50 concentration was optimal. The cause of the difference between the cytotoxic effects of two agents with this schedule is obscure. Demonstrating mechanisms, which are responsible for these differences, will be important for more rational use of taxoids and to provide basis for the following clinical trials.

Phase I pharmacokinetic and sequence finding study of the combination of docetaxel and methotrexate in patients with solid tumours

This phase I study was performed to assess the feasibility and possible enhanced antitumour activity of the sequential administration of methotrexate (MTX) and docetaxel (D) in patients with solid tumours. Pharmacokinetic analysis was performed to investigate the pharmacokinetic interaction of the two agents. A total of 22 patients were enrolled, a total of six dose levels were investigated. MTX (days 1+15) 30, 40 and 50 mg/m(2)+D (day 2 or day 1) 75 and 85 mg/m(2) with supportive care measures. Both haematological and non-haematological toxicities were significant, preventing dose escalation above MTX 40 mg/m(2)+D 75 mg/m(2). Four partial responses were documented, three in patients with breast cancer, one in a patient with urothelial cell cancer. Pharmacokinetic data did not give an explanation for the significant toxicity as they revealed no interaction of D and MTX kinetics. Methotrexate and 7-OH MTX kinetics seemed to be independent of the administration of D and the moment of D administration appeared not to influence MTX kinetics. The sequential administration of MTX and D results in significant toxicity without any evidence of a clinical benefit.

Present state and future prospects: a review of cooperative groups' adjuvant and neoadjuvant trials in breast cancer

In patients with operable breast cancer, adjuvant hormonal therapy and adjuvant chemotherapy result in significant and long-term reductions in the rates of disease recurrence and death. These reductions are evident in both patients with node-negative as well as in those with node-positive disease. However, several issues in the adjuvant treatment of breast cancer still remain unresolved. These issues were recently considered at the 2000 National Institutes of Health (NIH) Consensus Development Conference, which reviewed the current state of knowledge on adjuvant therapy and outlined strategies for future research. In the area of adjuvant hormonal therapy, tamoxifen is still the gold standard, and present evidence supports the use of tamoxifen for patients with estrogen receptor (ER)-positive tumors irrespective of age, menopausal status, nodal status, or tumor size. Optimal duration of tamoxifen therapy is about 5 years. Future research directions include evaluating the benefit of extending tamoxifen beyond 5 years, the contribution of ovarian ablation, and the role of hormonal manipulations involving selective ER modulators and aromatase inhibitors instead of or in addition to tamoxifen. In the area of adjuvant chemotherapy, polychemotherapy regimens have been consistently found to be superior to single agents, and anthracycline-containing regimens produce a small but statistically significant improvement in survival when compared with regimens not containing an anthracycline. High-dose adjuvant chemotherapy with stem cell support has not been proven superior to standard regimens. Neoadjuvant therapy offers the possibility of testing in vivo the sensitivity of individual tumors to particular cytotoxic regimens and, hence, of improving ultimate disease control, as well as reducing the extent of local therapy. The contribution and optimal integration of taxanes in the adjuvant setting are yet to be established but are the subject of intense research effort. Similarly, novel targeted therapies such as trastuzumab and bisphosphonates are currently being evaluated in adjuvant studies

Combining the anti-HER2 antibody trastuzumab with taxanes in breast cancer: results and trial considerations

Overexpression of the p185/HER2 protein is seen in 20%-25% of primary breast cancers and is associated with poor prognosis. Recent phase II and III clinical trials demonstrate that trastuzumab is active against breast tumors, both as a single agent and in combination with chemotherapy. In patients with HER2-overexpressing metastatic breast cancer, use of trastuzumab in combination with chemotherapy is associated with a 20% reduction in relative risk of death and an increase in median survival from 20.3 to 25.1 months compared to chemotherapy alone. Side effects include fever and chills and an unexpected increase in doxorubicin/trastuzumab-associated cardiomyopathy. Clinical development is now focused on trastuzumab in combination with chemotherapy regimens that do not contain an anthracycline. Trastuzumab in combination with docetaxel is synergistic in vitro. Data from ongoing clinical trials are consistent with this finding. Preliminary data from 3 phase II studies suggest a 44%-63% response rate when the combination is used first or second line in HER2-overexpressing metastatic breast cancer. The combination of docetaxel with trastuzumab is well tolerated and has not been associated with significant cardiotoxicity. Given in vitro evidence that platinum salts act synergistically with trastuzumab and docetaxel, and phase II data suggesting clinical efficacy and good tolerability, the combination of platinum salt plus trastuzumab and docetaxel is now being assessed in adjuvant trials

Primary (neoadjuvant) chemotherapy with docetaxel in breast cancer

The use of primary or neoadjuvant chemotherapy for locally advanced breast cancer, including those patients with inflammatory breast cancer, is well established. The use of primary chemotherapy has also been investigated in patients with operable breast cancer. The potential benefit of using primary chemotherapy is the opportunity to administer systemic therapy at an earlier timepoint, where it may be more effective against microscopic disease. In addition, primary chemotherapy for patients with operable breast cancer may also result in higher rates of breast conservation, axillary nodal downstaging, and potential improvement in patient outcome. A variety of different chemotherapy drugs have been evaluated in the primary chemotherapy setting. One of the most common approaches is to use an anthracycline-based regimen for 4 or more cycles of treatment before considering definitive local therapy. Although high tumor response rates have been reported using anthracycline-based regimens, the fraction of patients actually attaining a pathologic complete response has remained small (less than 20%). With the introduction of new chemotherapy drugs, such as docetaxel, which is associated with a very high tumor response rate in metastatic disease, a natural evolution of clinical investigation is to use docetaxel in the neoadjuvant or primary chemotherapy setting. Some of the recent trials that have evaluated single-agent docetaxel, docetaxel-based chemotherapy combinations, and novel sequencing strategies that include docetaxel in the neoadjuvant setting are reviewed. The results from these trials clearly suggest that docetaxel-containing treatment strategies can be considered a standard in the primary chemotherapy setting

Docetaxel: overview of an active drug for breast cancer

Docetaxel and paclitaxel differ in their precise molecular targets and pharmacokinetics. Docetaxel is more avidly taken up by tumor cell lines than paclitaxel, and its efflux is slower. Comparative cytotoxicity data suggest greater potency. These factors may help explain the clinical differences that have been observed between the taxanes in patients with breast cancer.

Nonanthracycline containing docetaxel-based combinations in metastatic breast cancer

Many active nonanthracycline-containing regimens are emerging from clinical trials and may offer the option of treating metastatic breast cancer without resorting to doxorubicin or analogues. When used first-line in metastatic breast cancer, both cisplatin and carboplatin are active agents and hence candidates for combination therapy. In a dose-finding study in patients with no prior chemotherapy for metastatic disease, docetaxel administered together with cisplatin produced a promising response rate (RR) of 60% (73% in patients without prior adjuvant chemotherapy). The combination is feasible, although adequate hydration and antiemetic medication must be given. There is also an early indication that it may be possible to dramatically cytoreduce disease in patients with locally advanced breast cancer who are treated with docetaxel plus cisplatin. Given its lower toxicity, carboplatin may also have a role in combination with the taxanes. Of the nonplatinum agents, vinorelbine appears to hold promise; its combination with docetaxel produced an RR of 59% in a group of anthracycline-pretreated patients with progressive disease. Forty-two percent of the patients studied also had prior exposure to a taxane. Weekly gemcitabine plus monthly docetaxel is feasible and active, as is the combination of docetaxel q 3 weeks with daily oral capecitabine.

Taxane/anthracycline combinations: setting a new standard in breast cancer?

Among the novel chemotherapeutic drugs introduced in the 1990s, the taxanes have emerged as the most powerful compounds in breast cancer. Both compounds, paclitaxel and docetaxel, have been evaluated in metastatic settings before adjuvant trials proceeded. Docetaxel was shown in several phase III trials to be superior, particularly in terms of survival, for salvaging polychemotherapies after failure of prior chemotherapy, including that with anthracyclines. A benefit of docetaxel was also reported when compared with doxorubicin after failure of alkylating agents. In phase III trials paclitaxel was reported to be as efficacious over 24 hours as doxorubicin 60 mg/m(2), while paclitaxel was significantly inferior to doxorubicin 75 mg/m(2) over 3 hours and was close to CMF in another trial. The role of taxanes in combination with anthracyclines in first-line therapy of advanced breast cancer is emerging. Following several phase II studies, a phase III trial showed the significant superiority of docetaxel/doxorubicin (AT) versus doxorubicin/cyclophosphamide (AC) in terms of response and time to progression. In several phase II studies with paclitaxel (3 hours), anthracyclines in the metastatic setting showed high efficacy but produced cardiac toxicity related to a pharmacokinetic interaction between the two agents. This finding led to the implementation of metastatic strategies (phase III trials) aimed at avoiding the pharmacokinetic interaction, while the adjuvant strategies with paclitaxel focused primarily on the sequential approach (AC followed by paclitaxel). In contrast, adjuvant strategies with docetaxel/anthracycline-based programs were implemented following both sequential and combination approaches.

Docetaxel and epirubicin in advanced breast cancer

In an International Breast Cancer Study Group phase I/II program, 70 patients with advanced breast cancer received up to eight courses of 75 mg/m2 docetaxel combined with 90 mg/m(2) epirubicin, every 3 weeks. G-CSF was not administered prophylactically. Grade 4 neutropenia occurred in 88% of cycles that were not supported by G-CSF. However, febrile neutropenia affected only 24% of cycles. It occurred after the first cycle in 56% of cases and was managed by oral antibiotics in 52% of cases. When supportive G-CSF was administered, the incidence of febrile neutropenia fell to 3% and grade 4 neutropenia to 41%. Only 6% of patients experienced a greater than 20% reduction in left ventricular ejection fraction and no severe, irreversible cardiotoxicity was observed. The overall response rate (RR) was 66% and median time to progression was 4.5 months. The RR was similar in patients with prior adjuvant chemotherapy and patients with predominantly visceral disease. These data and those of comparable series suggest that the combination of epirubicin and docetaxel is tolerable and active, and that it should be further developed clinically.

Weekly docetaxel in breast cancer: applying clinical data to patient therapy

The use of weekly 35-40 mg/m2 docetaxel, typically on a schedule of 6 weeks of therapy followed by a 2-week break, has produced response rates ranging from 33%-50% in patients with advanced breast cancer, the majority of whom have already received chemotherapy. These encouraging levels of response are seen across disease sites and in patients with prior anthracycline exposure. Importantly, the weekly administration of docetaxel allows prolonged treatment to a high cumulative dose: the weekly regimen is minimally myelotoxic, and neuropathy and other adverse events are infrequent. Weekly single-agent docetaxel may be a useful therapy in particular groups of patients such as those with reduced bone marrow reserve. It may also be a helpful means of delivering a highly active cytotoxic drug in combination with radiation therapy, other proven chemotherapy agents such as doxorubicin, and new, highly promising biological agents such as HERCEPTIN:

Capecitabine in breast cancer: current status

Anthracyclines, together with taxanes, are at present the most active agents in metastatic breast cancer, while single-agent, bolus 5-fluorouracil (5-FU) is not very active in this setting. In view of encouraging results and tolerable toxicity of continuous infusion of 5-FU in gastrointestinal cancer, innovative oral 5-FU agents such as capecitabine have been developed. Capecitabine is a prodrug that is converted into the active compound 5-FU preferentially at the tumor site. An intermittent dosing schedule of capecitabine twice daily at a dose of 2510 mg/m2/day on days 1-14 in a 3-week cycle appeared to be feasible and resulted in a high dose intensity. A large phase II study investigating capecitabine in 135 advanced breast cancer patients, pretreated with anthracyclines and taxanes, observed three complete and 24 partial responses (response rate, 20%), with a mean duration of 8.0 months. Preliminary results of a study comparing capecitabine with paclitaxel in 42 breast cancer patients failing anthracyclines indicate that the efficacy of capecitabine is comparable to that of paclitaxel, with response rates of 36% and 21%, respectively. Another study reported a response rate of 25% for capecitabine as first-line therapy for advanced breast cancer in women aged > or = 55 years, which tended to be better than combination chemotherapy with cyclophosphamide/methotrexate/5-FU. In all studies, capecitabine side effects were mainly mild, and treatment-related grade 3/4 toxicity consisted of diarrhea (8%-11%), nausea (4%-11%), hand-foot syndrome (10%-18%), neutropenia (3%-20%), and bilirubin elevation (6%). Capecitabine is clearly an active agent for the treatment of breast cancer. It is currently registered in various countries for use in third-line treatment of metastatic disease. Its further role will have to be defined from data of randomized phase III studies.