Efficacy of taxanes as adjuvant treatment of breast cancer: a review and meta-analysis of randomised clinical trials

A careful reassessment of anthracycline use in curable breast cancer

It has been over three decades since anthracyclines took their place as the standard chemotherapy backbone for breast cancer in the curative setting. Though the efficacy of anthracycline chemotherapy is not debatable, potentially life-threatening and long-term risks accompany this class of agents, leading some to question their widespread use, especially when newer agents with improved therapeutic indices have become available. Critically assessing when to incorporate an anthracycline is made more relevant in an era where molecular classification is enabling not only the development of biologically targeted therapeutics but also is improving the ability to better select those who would benefit from cytotoxic agents. This comprehensive analysis will present the problem of overtreatment in early-stage breast cancer, review evidence supporting the use of anthracyclines in the pre-taxane era, analyze comparative trials evaluating taxanes with or without anthracyclines in biologically unselected and selected patient populations, and explore published work aimed at defining anthracycline-sensitive tumor types.

Appraising the quality of meta-analysis for breast cancer treatment in the adjuvant setting: A systematic review

INTRODUCTION

Breast cancer is the tumor with highest incidence in women worldwide and adjuvant treatment is extremely important to achieve disease control. Given the relevance of systematic reviews, their rigor should be warranted to avoid biased conclusions. Our objective was to investigate the methodological quality of meta-analysis of early breast cancer adjuvant treatment.

MATERIAL AND METHODS

Comprehensive searches were performed using electronic databases from 1/1/2007 to 11/12/2018. All studies identified as a systematic review with meta-analysis investigating the efficacy of breast cancer adjuvant treatments were included. Two reviewers independently assessed titles and abstracts, then full-texts for eligibility. Quality was assessed using the Assessing the Methodological Quality of Systematic Reviews (AMSTAR) version 2 tool.

RESULTS

Of 950 citations retrieved, 66 studies (7.0%) were deemed eligible. Methodological quality was highly variable, median AMSTAR score 8.5 (IQR 7-9.5) and range 0-16. There was a weak positive correlation between journal impact factor and AMSTAR score (r = 0.17) and citation rate and AMSTAR score (r = 0.16). Cochrane Systematic Reviews were of higher quality than reviews from other journals. Overall confidence was critically low for 61 (92.4%) studies, and the least well-reported domains were the statement of conflict of interest and funding source for the included studies (4.6%), the report of a pre-defined study protocol (15.2%), and the description of details of excluded studies (6.1%).

CONCLUSIONS

Our findings reinforce concerns about the design, conduction and interpretation of meta-analysis in current literature. Methodological quality should be carefully considered and journal editors, decision makers and readers in general, must follow a critical approach to this studies.

Comparison between nab-paclitaxel and solvent-based taxanes as neoadjuvant therapy in breast cancer: a systematic review and meta-analysis

Background

To compare the efficacy and safety of nanoparticle albumin-bound paclitaxel (nab-paclitaxel) and solvent-based taxanes (sb-taxanes) as neoadjuvant therapy in the treatment of breast cancer.

Methods

We systematically searched the PubMed, Embase, and Cochrane Central Register databases. Randomized controlled trials (RCTs) and cohort studies, published in English, about the comparison between nab-paclitaxel and sb-taxanes as neoadjuvant therapy in patients with breast cancer were searched up to September 2019.

Results

The primary outcome was the proportion of patients with pathological complete response (pCR, defined as ypT0 ypN0 or ypT0/is ypN0). Other main outcomes included long-term survival and adverse events (AEs). Seven studies (five RCTs and two cohorts) and 2949 patients were included. Neoadjuvant nab-paclitaxel improved pCR compared with sb-taxanes (ypT0 ypN0: OR = 1.52, 95%CI: 1.27–1.83, P < 0.001; ypT0/is ypN0: OR = 1.40, 95%CI: 1.17–1.68, P < 0.001). The benefits of nab-paclitaxel on pCR were persistent in HER2-negative, hormone receptor (HR)-positive breast cancer (OR = 1.53, 95%CI: 1.07–2.19, P = 0.020), triple-negative breast cancer (weekly/every 2 weeks regimen; OR = 2.95, 95%CI: 1.54–5.67, P < 0.001), and tumors with Ki-67 > 20% (OR = 1.63, 95%CI: 1.26–2.12, P < 0.001). Patients treated with nab-paclitaxel had better event-free survival (EFS; HR = 0.69, 95%CI: 0.57–0.85, P < 0.001) than with sb-taxanes. There were no differences in most of grade > 3 AEs between nab-paclitaxel and sb-taxanes (all P > 0.05), besides of any grade hypersensitivity (OR = 0.29, 95%CI: 0.11–0.72, P = 0.008), any grade (OR = 2.10, 95%CI: 1.37–3.23, P = 0.001) and grade > 3 (OR = 4.01, 95%CI: 2.51–6.41, P < 0.001) neuropathy.

Conclusion

Nab-paclitaxel is effective for the treatment of non-metastatic breast cancer in the neoadjuvant setting. Nab-paclitaxel could improve pCR rate and EFS compared with sb-taxanes and with reasonable toxicities.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-07831-7.

Retrospective analysis of the effectiveness and tolerability of nab-paclitaxel in Chinese elderly patients with advanced non-small-cell lung carcinoma

BACKGROUND

Previous trials have suggested that elderly patients with non-small-cell lung cancer (NSCLC) could benefit from nanoparticle albumin-bound paclitaxel (nab-paclitaxel). Real-world data on the elderly Chinese population are lacking. This study aimed to analyze the effectiveness and tolerability of nab-paclitaxel in Chinese elderly patients (≥65 years) with advanced NSCLC.

METHODS

This study included 76 patients with a primary diagnosis of IIIB-IV NSCLC from January 2010 to December 2017 at Peking University Cancer Hospital, who received nab-paclitaxel (125 or 130 mg/m² i.v.) every three weeks. The overall survival (OS), progression-free survival (PFS), objective response rate (ORR), disease control rate (DCR), and adverse events (AEs) were analyzed.

RESULTS

There were 12 patients who received nab-paclitaxel as the first-line treatment (seven also received carboplatin), and 64 received nab-paclitaxel as the latter-line treatment. The overall ORR, DCR, median PFS, and median OS were 14.5%, 69.7%, 5.2 months, and 12.2 months, respectively. The Eastern Cooperative Oncology Group performance status of one and the age of 70-74 years were independently associated with longer OS, while early treatment line of nab-paclitaxel and age of 70-74 years were independently associated with longer PFS. The most common AEs were anemia, leukopenia, gastrointestinal reaction, fatigue, and peripheral neuropathy, which were all manageable. Dose adjustment or treatment discontinuation was encountered in 10 patients because of AEs. The incidence of AEs was not different among age subgroups.

CONCLUSIONS

Nab-paclitaxel has a good clinical response profile in Chinese elderly patients with stage IIIB-IV NSCLC. Prospective clinical trials are needed to confirm these results.

KEY POINTS

Significant findings of the study Nanoparticle albumin-bound paclitaxel (nab-paclitaxel) has a good clinical response profile in Chinese elderly (≥65 years) patients with stage IIIB-IV non-small-cell lung cancer (NSCLC), with acceptable and manageable adverse events. What this study adds Preliminary evidence shows a good clinical response from treatment with nab-paclitaxel in Chinese elderly patients with advanced NSCLC.

Nanopaclitaxel therapy: an evidence based review on the battle for next-generation formulation challenges

The poor solubility of paclitaxel (PTX), the most commonly used anticancer drug (Taxol^®), has long hindered the development of successful formulations. In 2005, the launch of Abraxane^®, a human albumin-based preparation of PTX, competed with Taxol^® in the commercial market. The success of Abraxane pushed other generic preparations aside, sparking competition among the global pharmaceutical companies to develop the novel and superior PTX nanotechnology-driven formulations. Unsurprisingly, the success underlying with cancer treatment using nano PTX therapy has now entered into a new era of drug development, patentability, preclinical and clinical evaluation, leading eventually to a significant increase in the regulatory approval of the products. The present article aims to provide recent progress in the development of nano PTX formulations by various pharmaceutical companies for safe and effective drug therapies for patients benefit.

Effectiveness of biosimilar filgrastim vs. original granulocyte colony-stimulating factors in febrile neutropenia prevention in breast cancer patients

PURPOSE

The purpose of this study is to describe the effectiveness of biosimilar filgrastim and original granulocyte colony-stimulating factors (G-CSFs), lenograstim and pegfilgrastim, in febrile neutropenia (FN) prevention in breast cancer patients receiving docetaxel/doxorubicin/cyclophosphamide (TAC) as adjuvant/neoadjuvant treatment and to analyze their treatment patterns.

METHODS

A pharmacoepidemiology cohort study was developed in a university hospital (with 23 healthcare centers) with retrospective data collection (2012-2014). Effectiveness of G-CSFs was assessed by the FN incidence. Other parameters analyzed were as follows: moderate and severe neutropenia incidence, neutropenia-related hospitalizations, dosage, and duration. Data was analyzed using each cycle as a unit of analysis.

RESULTS

We identified 98 patients representing 518 chemotherapy cycles, 215 with original G-CSFs (35 lenograstim and 180 pegfilgrastim) and 303 with biosimilar filgrastim. The FN incidence was similar in both groups (3.7% original vs. 3.3% biosimilar; p = 0.79). No statistically significant differences were found in moderate and severe neutropenia incidence (4.7 vs. 6.3%; p = 0.43) or neutropenia-related hospitalizations (3.3 vs. 3.6%; p = 0.19). When the three drugs were evaluated separately, a higher FN incidence was observed with lenograstim than with pegfilgratim or biosimilar (p = 0.024). The dosage and duration of biosimilar were lower than lenograstim (4.9 vs. 5.7 μg/kg/day; 5 vs. 7 days; p < 0.001).

CONCLUSION

An abbreviated 5-day course of biosimilar filgrastim provided optimal primary prophylaxis against FN post-chemotherapy TAC in patients with breast cancer. The clinical relevance of the highest FN incidence in the lenograstim cohort needs further attention.

ADAM12-L confers acquired 5-fluorouracil resistance in breast cancer cells

5-FU-based combinatory chemotherapeutic regimens have been routinely used for many years for the treatment of breast cancer patients. Recurrence and chemotherapeutic drug resistance are two of the most prominent factors that underpin the high mortality rates associated with most breast cancers (BC). Increasing evidence indicates that overexpression of ADAMs could correlate with cancer progression. However, the role of ADAMs in the chemoresistance of cancer cells has rarely been reported. In this study, we observed that 5-FU induces expression of the ADAM12 isoform ADAM12-L but not ADAM12-S in BC cells and in recurrent BC tissues. The overexpression of ADAM12-L in BC cells following 5-FU treatment results in the acquisition of resistance to 5-FU. ADAM12-L overexoression also resulted in increased levels of p-Akt but not p-ERK. These alterations enhanced BC cell growth and invasive abilities. Conversely, ADAM12 knockdown attenuated the levels of p-Akt and restored 5-FU sensitivity in 5-FU-resistant BC cells. ADAM12 knockdown also reduced BC cell survival and invasive abilities. These findings suggest that ADAM12-L mediates chemoresistance to 5-FU and 5-FU-induced recurrence of BC by enhancing PI3K/Akt signaling. The results of this study suggest that specific ADAM12-L inhibition could optimize 5-FU-based chemotherapy of BC, thereby preventing BC recurrence in patients.

A Review of Paclitaxel and Novel Formulations Including Those Suitable for Use in Dogs

Paclitaxel is a commonly used chemotherapeutic agent with a broad spectrum of activity against cancers in humans. In 1992, paclitaxel was approved by the U.S. Food and Drug Administration (FDA) as Taxol(®) for use in advanced ovarian cancer. Two years later, it was approved for the treatment of metastatic breast cancer. Paclitaxel was originally isolated from the bark of the Pacific yew tree, Taxus brevifolia in 1971. Taxanes are a family of microtubule inhibitors. As a member of this family, paclitaxel suppresses spindle microtubule dynamics. This activity results in the blockage of the metaphase-anaphase transitions, and ultimately in the inhibition of mitosis, and induction of apoptosis in a wide spectrum of cancer cells. Additional anticancer activities of paclitaxel have been defined that are independent of these effects on the microtubules and may include the suppression of cell proliferation as well as antiangiogenic effects. Based on its targeting of a fundamental feature of the cancer phenotype, the mitotic complex, it is not surprising that paclitaxel has been found to be active in a wide variety of cancers in humans. This review summarizes the evidence in support of paclitaxel's broad anticancer activity and introduces the rationale for, and the progress in development of novel formulations of paclitaxel that may preferentially target cancers and that are not associated with the risks for hypersensitivity in dogs. Of note, a novel nanoparticle formulation of paclitaxel that substantially limits hypersensitivity was recently given conditional approval by the FDA Center for Veterinary Medicine for use in dogs with resectable and nonresectable squamous cell carcinoma and nonresectable stage III, IV and V mammary carcinoma.

Adjuvant taxane-based chemotherapy for early stage breast cancer: a real-world comparison of chemotherapy regimens in Ontario

The purpose of this study was to compare survival and risk of adverse events in women with early stage breast cancer (BC) treated with (1) doxorubicin (A), cyclophosphamide (C) + paclitaxel (P), (2) fluorouracil (F), epirubicin (E), cyclophosphamide (C) + docetaxel (D), or (3) dose-dense AC-P. Retrospective cohort study including 8462 women aged ≥18 years, with resected stage I-III BC, diagnosed between 2003 and 2009 in Ontario, identified through linkage of administrative databases. Primary outcome is overall survival (OS). Secondary outcomes are emergency room (ER) visits/hospitalizations, heart failure (HF), and leukemia. 4710 women were treated with FEC-D, 2065 with AC-P, and 1687 with dd AC-P. Adjusted 5-year OS was 92.1, 87.7, and 90.3 %, for each regimen, respectively (p = 0.0006). There was no difference in OS for FEC-D and dd AC-P in the propensity score-matched analyses (HR 1.24, 95 % CI 0.99-1.55). Five-year risk of HF was also similar (HR 1.09; 0.66-1.791.4 % for dd AC-P and 1.3 % for FEC-D and, p = 0.72). Treatment with FEC-D was significantly associated with ER visits and hospital admissions (p < 0.0001). The risks of leukemia were low and similar among the 3 groups (AC-P: 0.34 %, FEC-D: 0.08 %, dd AC-P: 0.12 %; p = 0.09). Although the efficacy of the three regimens was similar to that observed in randomized trials, we report higher toxicity with the use of these regimens in clinical practice. This was especially concerning for the docetaxel-containing regimen.

PTK7 as a potential prognostic and predictive marker of response to adjuvant chemotherapy in breast cancer patients, and resistance to anthracycline drugs

Biomarkers predicting resistance to particular chemotherapy regimens could play a key role in optimally individualized treatment concepts. PTK7 (protein tyrosine kinase 7) belongs to the receptor tyrosine kinase family involved in several physiological, but also malignant, cell behaviors. Recent studies in acute myeloid leukemia have associated PTK7 expression with resistance to anthracycline therapy. PTK7 mRNA expression in primary tumor tissue (PTT) and corresponding lymph node tissue (LNT) were retrospectively measured in 117 patients with early breast cancer; PTK7 expression was available in 103 PTT and 108 LNT samples. Median age was 60 years (range, 27-87 years). At a median follow-up of 28.5 months, 6 deaths and 16 recurrences had occurred. PTK7 expression correlations with clinicopathological features were computed and PTK7 expression effects on patient outcome were analyzed in three cohorts defined by adjuvant treatment: anthracycline-based treatment, other chemotherapy regimens (including taxane or other substances), or no chemotherapy. Association of PTK7 expression with clinicopathological features was seen only for age in PTT and nodal stage in LNT. High LN PTK7 was associated with poorer disease-free survival (DFS) in the total population (3-year DFS: low [81.7%] versus high [70.4%]; P=0.016) and in patients without adjuvant chemotherapy (3-year DFS: low [91.7%] versus high [22.3%]; P<0.001), but not in patients receiving adjuvant chemotherapy (P=0.552). DFS stratified by PTK7 expression was compared in treatment cohorts: In patients with low LN PTK7 expression, neither chemotherapy cohort showed significantly better survival than the no-chemotherapy cohort. In patients with high LN PTK7 expression, those receiving chemotherapy, including substances other than anthracyclines, but not those receiving only anthracycline-based chemotherapy, showed significantly better DFS than those receiving no chemotherapy (P=0.001). Our results support earlier findings that PTK7 may be a prognostic and predictive marker associated with resistance to anthracycline-based chemotherapy. Further investigations are needed to validate these findings in breast cancer.

Model-based meta-analysis for quantifying Paclitaxel dose response in cancer patients

Model-based meta-analysis of dose response is a sophisticated method to guide dose and regimen selection. In this report, the effects of paclitaxel dose and regimen (weekly or every 3 weeks) on the efficacy and safety in cancer patients were quantified by model-based meta-analysis of 29 monotherapy trials. Logistic regression models were developed to assess the relationship between dose and objective response rate or neutropenia rate. Survival models were developed to assess the relationship between dose and overall survival or progression-free survival. Paclitaxel efficacy (e.g., objective response rate, median overall survival, and progression-free survival) is correlated with average dose per week (mg/m²/week), whereas safety (e.g., neutropenia rate) is correlated with dose per administration (mg/m²). Weekly paclitaxel regimen at 65–80 mg/m² is supported to have comparable to better efficacy and lower neutropenia incidence than an every-3-week regimen at 175 mg/m².

Delayed triggering of oestrogen induced apoptosis that contrasts with rapid paclitaxel-induced breast cancer cell death

Background:

Oestrogen (E₂) induces apoptosis in long-term E₂-deprived MCF7 cells (MCF7:5C). Taxanes have been used extensively in the treatment of early and advanced breast cancer. We have interrogated the sequence of events that involve the apoptotic signalling pathway induced by E₂ in comparison with paclitaxel.

Methods:

DNA quantification and cell cycle analysis were used to assess proliferation of cancer cells. Apoptosis was evaluated using annexin V and DNA staining methods. Regulation of apoptotic genes was determined by performing PCR-based arrays and RT–PCR.

Results:

E₂-induced apoptosis is a delayed process, whereas paclitaxel immediately inhibits the growth and induces death of MCF7:5C cells. The cellular commitment for E₂-triggered apoptosis occur after 24 h. Activation of the intrinsic pathway was observed by 36 h of E₂ treatment with subsequent induction of the extrinsic apoptotic pathway by 48 h. Paclitaxel exclusively activated extramitochodrial apoptotic genes and caused rapid G2/M blockade by 12 h of treatment. By contrast, E₂ causes an initial proliferation with elevated S phase of cell cycles followed by apoptosis of the MCF7:5C cells. Most importantly, we are the first to document that E₂-induced apoptosis can be reversed after 24 h treatment.

Conclusions:

These data indicate that E₂-induced apoptosis involves a novel, multidynamic process that is distinctly different from that of a classic cytotoxic chemotherapeutic drug used in breast cancer.

Real-world impact of granulocyte-colony stimulating factor on febrile neutropenia

BACKGROUND

Primary prophylaxis with granulocyte colony-stimulating factors (pp-g-csf) is recommended in patients undergoing chemotherapy carrying a febrile neutropenia (fn) risk of 20% or more. In the present study, we examined clinical practice patterns and the impact of pp-g-csf on fn incidence in women with early-stage breast cancer (ebc) treated with modern adjuvant chemotherapy (act).

METHODS

This single-centre retrospective cohort study of women with ebc, who were identified from the pharmacy database and who received at least 1 cycle of modern act from January 2009 to December 2011, was conducted at the Cancer Centre of Southeastern Ontario. Data on patient demographics, pathology, stage distribution, chemotherapy, pp-g-csf use, dose reductions, chemotherapy delays, treatment discontinuation, relative dose intensity, and fn events were collected. Chi-square tests, t-tests, univariate and multivariate logistic regression analyses, and nonparametric Mann-Whitney U-tests were used for data analysis.

RESULTS

Of the 239 women eligible for analysis, 145 (61%) received pp-g-csf, and 50 (21%) developed at least 1 episode of fn. Use of pp-g-csf was associated with a significantly lower rate of fn (14% vs. 31%, p = 0.002) and trends to fewer dose delays (17% vs. 27%, p = 0.060) and dose reductions (19% vs. 25%, p = 0.28). Among women receiving pp-g-csf, higher fn rates were associated with an age of 65 years or older, taxane-based chemotherapy, and prophylaxis with filgrastim.

CONCLUSIONS

Clinical practice patterns at our institution showed that more than 50% of ebc patients treated with modern act received pp-g-csf, which led to fewer fn episodes and increased delivery of planned act. The observed high fn risk despite pp-g-csf was linked to older age, taxane-based chemotherapy, and filgrastim.

CYP2C8*3 increases risk of neuropathy in breast cancer patients treated with paclitaxel

BACKGROUND

Paclitaxel-induced neuropathy is an adverse event that often leads to therapeutic disruption and patient discomfort. We attempted to replicate a previously reported association between increased neuropathy risk and CYP2C8*3 genotype.

PATIENTS AND METHODS

Demographic, treatment, and toxicity data were collected for paclitaxel-treated breast cancer patients who were genotyped for the CYP2C8*3 K399R (rs10509681) variant. A log-rank test was used in the primary analysis of European-American patients. An additional independent replication was then attempted in a cohort of African-American patients, followed by modeling of the entire patient cohort with relevant covariates.

RESULTS

In the primary analysis of 209 European patients, there was an increased risk of paclitaxel-induced neuropathy related to CYP2C8*3 status [HR (per allele) = 1.93 (95% CI: 1.05-3.55), overall log-rank P = 0.006]. The association was replicated in direction and magnitude of effect in 107 African-American patients (P = 0.043). In the Cox model using the entire mixed-race cohort (n = 411), each CYP2C8*3 allele approximately doubled the patient's risk of grade 2+ neuropathy (P = 0.004), and non-Europeans were at higher neuropathy risk than Europeans of similar genotype (P = 0.030).

CONCLUSIONS

The increased risk of paclitaxel-induced neuropathy in patients who carry the CYP2C8*3 variant was replicated in two racially distinct patient cohorts.

Apicidin and docetaxel combination treatment drives CTCFL expression and HMGB1 release acting as potential antitumor immune response inducers in metastatic breast cancer cells

Currently approved combination regimens available for the treatment of metastatic tumors, such as breast cancer, have been shown to increase response rates, often at the cost of a substantial increase in toxicity. An ideal combination strategy may consist of agents with different mechanisms of action leading to complementary antitumor activities and safety profiles. In the present study, we investigated the effects of the epigenetic modulator apicidin in combination with the cytotoxic agent docetaxel in tumor breast cell lines characterized by different grades of invasiveness. We report that combined treatment of apicidin and docetaxel, at low toxicity doses, stimulates in metastatic breast cancer cells the expression of CTCF-like protein and other cancer antigens, thus potentially favoring an antitumor immune response. In addition, apicidin and docetaxel co-treatment specifically stimulates apoptosis, characterized by an increased Bax/Bcl-2 ratio and caspase-8 activation. Importantly, following combined exposure to these agents, metastatic cells were also found to induce signals of immunogenic apoptosis such as cell surface expression of calreticulin and release of considerable amounts of high-mobility group box 1 protein, thus potentially promoting the translation of induced cell death into antitumor immune response. Altogether, our results indicate that the combined use of apicidin and docetaxel, at a low toxicity profile, may represent a potential innovative strategy able to activate complementary antitumor pathways in metastatic breast cancer cells, associated with a potential control of metastatic growth and possible induction of antitumor immunity.

The triterpenoid cucurbitacin B augments the antiproliferative activity of chemotherapy in human breast cancer

Despite recent advances in therapy, breast cancer remains the second most common cause of death from malignancy in women. Chemotherapy plays a major role in breast cancer management, and combining chemotherapeutic agents with nonchemotherapeutic agents is of considerable clinical interest. Cucurbitacins are triterpenes compounds found in plants of the Cucurbitaceae family, reported to have anticancer and anti-inflammatory activities. Previously, we have shown antiproliferative activity of cucurbitacin B (CuB) in breast cancer, and we hypothesized that combining CuB with chemotherapeutic agents can augment their antitumor effect. Here, we show that a combination of CuB with either docetaxel (DOC) or gemcitabine (GEM) synergistically inhibited the proliferation of MDA-MB-231 breast cancer cells in vitro. This antiproliferative effect was accompanied by an increase in apoptosis rates. Furthermore, in vivo treatment of human breast cancer orthotopic xenografts in immunodeficient mice with CuB at either low (0.5 mg/kg) or high (1 mg/kg) doses in combination with either DOC (20 mg/kg) or GEM (12.5mg/kg) significantly reduced tumor volume as compared with monotherapy of each drug. Importantly, no significant toxicity was noted with low-dose CuB in combination with either DOC or GEM. In conclusion, combination of CuB at a relatively low concentration with either of the chemotherapeutic agents, DOC or GEM, shows prominent antiproliferative activity against breast cancer cells without increased toxicity. This promising combination should be examined in therapeutic trials of breast cancer.

Molecular-targeted nanotherapies in cancer: enabling treatment specificity

Chemotherapy represents a mainstay and powerful adjuvant therapy in the treatment of cancer. The field has evolved from drugs possessing all-encompassing cell-killing effects to those with highly targeted, specific mechanisms of action; a direct byproduct of enhanced understanding of tumorigenic processes. However, advances regarding development of agents that target key molecules and dysregulated pathways have had only modest impacts on patient survival. Several biological barriers preclude adequate delivery of drugs to tumors, and remain a formidable challenge to overcome in chemotherapy. Currently, the field of nanomedicine is enabling the delivery of chemotherapeutics, including repositioned drugs and siRNAs, by giving rise to carriers that provide for protection from degradation, prolonged circulation times, and increased tumor accumulation, all the while resulting in reduced patient morbidity. This review aims to highlight several innovative, nanoparticle-based platforms with the potential of providing clinical translation of several novel chemotherapeutic agents. We will also summarize work regarding the development of a multistage drug delivery strategy, a robust carrier platform designed to overcome several biological barriers while en route to tumors.