Docetaxel. A review of its pharmacodynamic and pharmacokinetic properties and therapeutic efficacy in the management of metastatic breast cancer

Boosting antitumor efficacy using docetaxel-loaded nanoplatforms: from cancer therapy to regenerative medicine approaches

The intersection of nanotechnology and pharmacology has revolutionized the delivery and efficacy of chemotherapeutic agents, notably docetaxel, a key drug in cancer treatment. Traditionally limited by poor solubility and significant side effects, docetaxel's therapeutic potential has been significantly enhanced through its incorporation into nanoplatforms, such as nanofibers and nanoparticles. This advancement offers targeted delivery, controlled release, and improved bioavailability, dramatically reducing systemic toxicity and enhancing patient outcomes. Nanofibers provide a versatile scaffold for the controlled release of docetaxel, utilizing techniques like electrospinning to tailor drug release profiles. Nanoparticles, on the other hand, enable precise drug delivery to tumor cells, minimizing damage to healthy tissues through sophisticated encapsulation methods such as nanoprecipitation and emulsion. These nanotechnologies not only improve the pharmacokinetic properties of docetaxel but also open new avenues in regenerative medicine by facilitating targeted therapy and cellular regeneration. This narrative review highlights the transformative impact of docetaxel-loaded nanoplatforms in oncology and beyond, showcasing the potential of nanotechnology to overcome the limitations of traditional chemotherapy and pave the way for future innovations in drug delivery and regenerative therapies. Through these advancements, nanotechnology promises a new era of precision medicine, enhancing the efficacy of cancer treatments while minimizing adverse effects.

Epstein-Barr Virus: Human Interactome Reveals New Molecular Insights into Viral Pathogenesis for Potential Therapeutics and Antiviral Drug Discovery

Host-virus Protein-Protein Interactions (PPIs) play pivotal roles in biological processes crucial for viral pathogenesis and by extension, inform antiviral drug discovery and therapeutics innovations. Despite efforts to develop the Epstein-Barr virus (EBV)-host PPI network, there remain significant knowledge gaps and a limited number of interacting human proteins deciphered. Furthermore, understanding the dynamics of the EBV-host PPI network in the distinct lytic and latent viral stages remains elusive. In this study, we report a comprehensive map of the EBV-human protein interactions, encompassing 1752 human and 61 EBV proteins by integrating data from the public repository HPIDB (v3.0) as well as curated high-throughput proteomic data from the literature. To address the stage-specific nature of EBV infection, we generated two detailed subset networks representing the latent and lytic stages, comprising 747 and 481 human proteins, respectively. Functional and pathway enrichment analysis of these subsets uncovered the profound impact of EBV proteins on cancer. The identification of highly connected proteins and the characterization of intrinsically disordered and cancer-related proteins provide valuable insights into potential therapeutic targets. Moreover, the exploration of drug-protein interactions revealed notable associations between hub proteins and anticancer drugs, offering novel perspectives for controlling EBV pathogenesis. This study represents, to the best of our knowledge, the first comprehensive investigation of the two distinct stages of EBV infection using high-throughput datasets. This makes a contribution to our understanding of EBV-host interactions and provides a foundation for future drug discovery and therapeutic interventions.

Chemotherapeutic properties and side-effects associated with the clinical practice of terpene alkaloids: paclitaxel, docetaxel, and cabazitaxel

Over the years, many biological and synthetic agents have been explored and tested in attempts to halt the spread of cancer and/or cure it. Currently, several natural compounds have and are being considered in this regard. For example, paclitaxel is a potent anticancer drug that originates from the tree Taxus brevifolia. Paclitaxel has several derivatives, namely, docetaxel and cabazitaxel. These agents work by disrupting microtubule assembling dynamics and inducing cell cycle arrest at the G2/M phase of the cell cycle, ultimately triggering apoptosis. Such features have helped to establish paclitaxel as an authoritative therapeutic compound against neoplastic disorders. After the completion of compound (hemi) synthesis, this drug received approval for the treatment of solid tumors either alone or in combination with other agents. In this review, we explore the mechanisms of action of paclitaxel and its derivatives, the different formulations available, as well as the molecular pathways of cancer resistance, potential risks, and other therapeutic applications. In addition, the role of paclitaxel in hematological malignancies is explored, and potential limitations in the therapeutic use of paclitaxel at the clinical level are examined. Furthermore, paclitaxel is known to cause increased antigen presentation. The immunomodulatory potential of taxanes, alone or in combination with other pharmacologic agents, is explored. Despite terpene-alkaloids derivatives' anti-mitotic potential, the impact of this class of drugs on other oncogenic pathways, such as epithelial-to-mesenchymal transition and the epigenetic modulation of the transcription profile of cancer cells, is also analyzed, shedding light on potential future chemotherapeutic approaches to cancer.

Investigation of the apoptosis-inducing effect of docetaxel by a comprehensive LC-MS based metabolomics and network pharmacology approaches

Docetaxel is one of the clinical first-line drugs and its combination with other chemotherapy agents for advanced or metastatic cancers has attracted widespread attention. Therefore, to promote the clinical application of docetaxel alone or in combination, a comprehensive investigation of the metabolic mechanism of docetaxel is of great importance. Here, we apply an integrative analysis of metabolomics and network pharmacology to elucidate the underlying mechanisms of docetaxel. After taking the intersection of the above two methods, 5 pathways including ABC transporters, Central carbon metabolism in cancer, Glycolysis and Gluconeogenesis, Cysteine and methionine metabolism, and Arginine biosynthesis have been screened out. In concern of the interaction network of these pathways and the anti-apoptosis effect of docetaxel itself, the Central carbon metabolism in cancer pathway was mainly focused. This study may help delineate global landscapes of cellular protein-metabolite interactions, to provide molecular insights about their mechanisms of action, to promote the clinical applications at well.

Cystine supplementation rebalances the redox homeostasis of microenvironment in non-small cell lung cancer cells and reverses their resistance to docetaxel

Continuous docetaxel (DTX) treatment of non-small cell lung cancer induces development of drug resistance, but the mechanism is poorly understood. In this study we performed metabolomics analysis to characterize the metabolic patterns of sensitive and resistant A549 non-small cell lung cancer cells (A549/DTX cells). We showed that the sensitive and resistant A549 cells exhibited distinct metabolic phenotypes: the resistant cells were characterized by an altered microenvironment of redox homeostasis with reduced glutathione and elevated reactive oxygen species (ROS). DTX induction reprogrammed the metabolic phenotype of the sensitive cells, which acquired a phenotype similar to that of the resistant cells: it reduced cystine influx, inhibited glutathione biosynthesis, increased ROS and decreased glutathione/glutathione disulfide (GSH/GSSG); the genes involved in glutathione biosynthesis were dramatically depressed. Addition of the ROS-inducing agent Rosup (25, 50 μg/mL) significantly increased P-glycoprotein expression and reduced intracellular DTX in the sensitive A549 cells, which ultimately acquired a phenotype similar to that of the resistant cells. Supplementation of cystine (1.0 mM) significantly increased GSH synthesis, rebalanced the redox homeostasis of A549/DTX cells, and reversed DTX-induced upregulation of P-glycoprotein, and it markedly improved the effects of DTX and inhibited the growth of A549/DTX in vitro and in vivo. These results suggest that microenvironmental redox homeostasis plays a key role in the acquired resistance of A549 cancer cells to DTX. The enhancement of GSH synthesis by supplementary cystine is a promising strategy to reverse the resistance of tumor cells and has potential for translation in the clinic.

Hypoxia Engineered Bone Marrow Mesenchymal Stem Cells Targeting System with Tumor Microenvironment Regulation for Enhanced Chemotherapy of Breast Cancer

Improving the tumor targeting of docetaxel (DTX) would not only be favored for the chemotherapeutic efficacy, but also reduce its side effects. However, the regulation of the tumor microenvironment could further inhibit the growth of tumors. In this study, we introduced a system consisting of hypoxia-engineered bone marrow mesenchymal stem cells (H-bMSCs) and DTX micelles (DTX-M) for breast cancer treatment. First, the stem cell chemotherapy complex system (DTX@H-bMSCs) with tumor-targeting ability was constructed according to the uptake of DTX-M by hypoxia-induced bMSCs (H-bMSCs). DTX micellization improved the uptake efficiency of DTX by H-bMSCs, which equipped DTX@H-bMSCs with satisfactory drug loading and stability. Furthermore, the migration of DTX@H-bMSCs revealed that it could effectively target the tumor site and facilitate the drug transport between cells. Moreover, in vitro and in vivo pharmacodynamics of DTX@H-bMSCs exhibited a superior antitumor effect, which could promote the apoptosis of 4T1 cells and upregulate the expression of inflammatory factors at the tumor site. In brief, DTX@H-bMSCs enhanced the chemotherapeutic effect in breast cancer treatment.

δ-Tocopherol Enhances Docetaxel-Induced Growth Inhibition and Apoptosis in Ovarian Cancer SKOV3 Cells

Docetaxel is the first-line chemotherapeutic drug for ovarian cancer. However, its clinical use is limited owing to its serious side effects. Therefore, it is of great clinical significance to enhance the efficacy of docetaxel at lower doses in a less-toxic manner. In this study, we investigated whether δ-tocopherol could enhance the anti-tumor effects of docetaxel on ovarian cancer SKOV3 cells in vitro. For docetaxel and δ-tocopherol, IC50 values of 1.89 nM and 11.41 µM, respectively, were obtained, in SKOV3 cells. The combination of δ-tocopherol and docetaxel had a synergistic cell growth inhibition effect, with lower cell viability and more cell arrest at the S phase compared to either δ-tocopherol or docetaxel alone. In addition, the combination of δ-tocopherol and docetaxel had a synergistic cell apoptosis induction effect, with more apoptotic cells and reduced anti-apoptotic protein expression compared to either δ-tocopherol or docetaxel alone. Furthermore, we identified 3 hoursub genes (CAT, EP300, CREBBP), which predicted the prognosis of ovarian cancer, which correlated with δ-tocopherol and docetaxel. In conclusion, the combination of δ-tocopherol and docetaxel presented synergistic cell growth inhibition and cell apoptosis induction effects in SKOV3 cells at a low dose, which suggesting that δ-tocopherol could improve the serious side effects of docetaxel.

Docetaxel/dimethyl-β-cyclodextrin inclusion complexes: preparation, in vitro evaluation and physicochemical characterization

Despite the development in novel drug delivery techniques and synthesis of multifunctional excipients, oral delivery of hydrophobic drug like docetaxel (DTX) is still challenging. The present work investigates the inclusion complexation of DTX, and dimethyl-β-cyclodextrin (DM-β-CD) to improve the solubility, dissolution and permeability of the drug. Amongst the native and modified β-cyclodextrins, DM-β-CD showed the highest solubility of DTX. Solid binary inclusion complex (IC) of DTX with DM-β-CD was prepared by solvent evaporation technique and thoroughly characterized for solubility, dissolution, permeability, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance (¹H NMR). The aqueous solubility and in vitro dissolution rate of DTX/DM-β-CD IC were markedly increased by 76.04- and 3.55-fold compared to free DTX powder. The permeability of DTX/DM-β-CD IC showed similar absorptive permeability but decreased efflux from the absorbed DTX, compared to pure DTX. Further, physicochemical studies of IC revealed the change of crystalline state DTX to its amorphous form. Moreover, FT-IR and ¹H NMR results indicate the formation of true inclusion complex between DTX and DM-β-CD at 1:1 molar ratio. Collectively, solid inclusion complexes prepared by spray drying method can be an effective strategy to enhance the biopharmaceutical performance of a highly hydrophobic drug DTX.

Strategies to better treat glioblastoma: antiangiogenic agents and endothelial cell targeting agents

Glioblastoma multiforme (GBM) is the most prevalent and aggressive form of glioma, with poor prognosis and high mortality rates. As GBM is a highly vascularized cancer, antiangiogenic therapies to halt or minimize the rate of tumor growth are critical to improving treatment. In this review, antiangiogenic therapies, including small-molecule drugs, nucleic acids and proteins and peptides, are discussed. The authors further explore biomaterials that have been utilized to increase the bioavailability and bioactivity of antiangiogenic factors for better antitumor responses in GBM. Finally, the authors summarize the current status of biomaterial-based targeting moieties that target endothelial cells in GBM to more efficiently deliver therapeutics to these cells and avoid off-target cell or organ side effects.

Advances in Gold Nanoparticle-Based Combined Cancer Therapy

According to the global cancer observatory (GLOBOCAN), there are approximately 18 million new cancer cases per year worldwide. Cancer therapies are largely limited to surgery, radiotherapy, and chemotherapy. In radiotherapy and chemotherapy, the maximum tolerated dose is presently being used to treat cancer patients. The integrated development of innovative nanoparticle (NP) based approaches will be a key to address one of the main issues in both radiotherapy and chemotherapy: normal tissue toxicity. Among other inorganic NP systems, gold nanoparticle (GNP) based systems offer the means to further improve chemotherapy through controlled delivery of chemotherapeutics, while local radiotherapy dose can be enhanced by targeting the GNPs to the tumor. There have been over 20 nanotechnology-based therapeutic products approved for clinical use in the past two decades. Hence, the goal of this review is to understand what we have achieved so far and what else we can do to accelerate clinical use of GNP-based therapeutic platforms to minimize normal tissue toxicity while increasing the efficacy of the treatment. Nanomedicine will revolutionize future cancer treatment options and our ultimate goal should be to develop treatments that have minimum side effects, for improving the quality of life of all cancer patients.

A novel view of the separate and simultaneous binding effects of docetaxel and anastrozole with calf thymus DNA: Experimental and in silico approaches

DNA stands as the primary purpose of many anticancer drugs and according to the performed research on this field, some certain changes contain crucial functionalities in the regulated transcription of DNA. Therefore, the interaction between anticancer drugs and DNA play an important role in understanding their function and also provide a better groundwork for producing more efficient and newer drugs. Here, the interaction between Docetaxel (DO) and calf thymus DNA (ct DNA), in the presence and absence of Anastrozole (AN), has been examined through the usage of different methods that include isothermal titration calorimetry, multi-spectroscopic, viscometry, and molecular docking techniques. Interaction studies have been performed by preparing different molar ratios of DO with the constant ct DNA and AN concentration at pH = 6.8. The binding constants have been calculated to be 7.93 × 10⁴ M^-1 and 6.27 × 10⁴ M^-1, which indicate the strong binding of DO with ct DNA double helix in the absence and presence of AN, respectively. Thermodynamic parameters, which were obtained from fluorescence spectroscopy and isothermal titration calorimetry, have suggested that the binding of DO and AN to ct DNA as binary and ternary systems have been mainly driven by the electrostatic interactions. The relative viscosity of ct DNA has increased upon the addition of DO and AN, which confirms the interaction mode. A competitive binding study has reported that the enhanced emission intensity of ethidium bromide (EB) and acridine orange (AO), in the presence of ct DNA, have been quenched through the addition of DO and Anastrozole as binary and ternary systems. As it is indicated by these findings, DO is capable of displacing EB and AO from their binding site in ct DNA; hence, it can be concluded that DO and AN are able to intercalate into the base pairs of ct DNA in binary and ternary systems. Molecular docking studies have corroborated the mentioned experimental results.

Network Pharmacology-Based identification of pharmacological mechanism of SQFZ injection in combination with Docetaxel on lung cancer

Docetaxel is the widely-used first-line therapy to treat lung cancer around the world. However, tumor progression and severe side effect occurred in some patients with docetaxel treatment. Most of the side effects were caused by immunocompromise, which limits the long-term use of docetaxel. Shenqi Fuzheng (SQFZ) injection has been used as adjuvant therapy to treat lung cancer which may enhance immunity as well. Owing to the complexity of drug combination, the mechanism of SQFZ injection in combination with docetaxel on lung cancer remains unclear. Therefore, a network pharmacology-based strategy was proposed in this study to help solve this problem. Network pharmacology approach comprising multiple components, candidate targets of component and therapeutic targets, has been used in this study. Also, in vivo and in vitro experiment was applied to verify the predicted targets from network pharmacology We established mouse lung cancer model and inject with docetaxel and SQFZ injection. Tumour weight, spleen index, thymus index, immunohistochemical staining and ELISA were conducted to evaluate the effect and underlying mechanisms of docetaxel and SQFZ injection. Besides A549 cells were also administrated by docetaxel and SQFZ.The indexes BCL2, CASP3 and CASP9 were determined after administration. The results indicated that combination of SQFZ and docetaxel could reduce tumour weight, enhance the spleen index, thymus index. Meanwhile, it could improve the activity of caspase-3 and IL-2 in mice and caspase-3, caspase-9 in A549 cell and inhibit the activity of BCL-2 in A549 cell, which verified the potential protective targets predicted by network pharmacology. In conclusion, combination of SQFZ and docetaxel could increase the curative effect by inducing tumour to apoptosis and play a key role on immunoprotection to reduce side effects.

Predicting drug response of tumors from integrated genomic profiles by deep neural networks

BACKGROUND

The study of high-throughput genomic profiles from a pharmacogenomics viewpoint has provided unprecedented insights into the oncogenic features modulating drug response. A recent study screened for the response of a thousand human cancer cell lines to a wide collection of anti-cancer drugs and illuminated the link between cellular genotypes and vulnerability. However, due to essential differences between cell lines and tumors, to date the translation into predicting drug response in tumors remains challenging. Recently, advances in deep learning have revolutionized bioinformatics and introduced new techniques to the integration of genomic data. Its application on pharmacogenomics may fill the gap between genomics and drug response and improve the prediction of drug response in tumors.

RESULTS

We proposed a deep learning model to predict drug response (DeepDR) based on mutation and expression profiles of a cancer cell or a tumor. The model contains three deep neural networks (DNNs), i) a mutation encoder pre-trained using a large pan-cancer dataset (The Cancer Genome Atlas; TCGA) to abstract core representations of high-dimension mutation data, ii) a pre-trained expression encoder, and iii) a drug response predictor network integrating the first two subnetworks. Given a pair of mutation and expression profiles, the model predicts IC50 values of 265 drugs. We trained and tested the model on a dataset of 622 cancer cell lines and achieved an overall prediction performance of mean squared error at 1.96 (log-scale IC50 values). The performance was superior in prediction error or stability than two classical methods (linear regression and support vector machine) and four analog DNN models of DeepDR, including DNNs built without TCGA pre-training, partly replaced by principal components, and built on individual types of input data. We then applied the model to predict drug response of 9059 tumors of 33 cancer types. Using per-cancer and pan-cancer settings, the model predicted both known, including EGFR inhibitors in non-small cell lung cancer and tamoxifen in ER+ breast cancer, and novel drug targets, such as vinorelbine for TTN-mutated tumors. The comprehensive analysis further revealed the molecular mechanisms underlying the resistance to a chemotherapeutic drug docetaxel in a pan-cancer setting and the anti-cancer potential of a novel agent, CX-5461, in treating gliomas and hematopoietic malignancies.

CONCLUSIONS

Here we present, as far as we know, the first DNN model to translate pharmacogenomics features identified from in vitro drug screening to predict the response of tumors. The results covered both well-studied and novel mechanisms of drug resistance and drug targets. Our model and findings improve the prediction of drug response and the identification of novel therapeutic options.

Docetaxel increases the risk of severe infections in the treatment of non-small cell lung cancer: a meta-analysis

The purpose of this study was to determine whether docetaxel increases the risk of severe infections in patients with non-small cell lung cancer. A thorough literature search of the PubMed, EMBASE and Cochrane Central Register of Controlled Trials databases was performed (up to February 28, 2017) without any language restrictions. In addition, we searched the www.clinicaltrials.gov website and checked each reference listed in the included studies, relevant reviews and guidelines. We also included randomized controlled trials that reported severe infections in patients with non-small cell lung cancer who were administered docetaxel. A meta- analysis was conducted using relative risk and random effects models in Stata 14.0 software. Sensitivity analysis and meta-regression were performed using Stata 14.0 software. We identified 354 records from the initial search, and this systematic review ultimately included 43 trials with 12,447 participants. The results of our meta- analysis showed that docetaxel increased the risk of severe infections [relative risk: 2.10, 95% confidence interval: 1.51-2.93, I² = 69.6%, P = 0.000]. Meta-regression analysis indicated that the type of intervention was a major source of heterogeneity. Our systematic review and meta-analysis suggest that docetaxel is associated with the risk of severe infections.

Extracellular vesicles from triple-negative breast cancer cells promote proliferation and drug resistance in non-tumorigenic breast cells

Purpose

Triple-negative breast cancer (TNBC), an aggressive breast cancer subtype, is genetically heterogeneous which challenges the identification of clinically effective molecular makers. Extracellular vesicles (EVs) are key players in the intercellular signaling communication and have been shown to be involved in tumorigenesis. The main goal of this study was to evaluate the role and mechanisms of EVs derived from TNBC cells in modulating proliferation and cytotoxicity to chemotherapeutic agents in non-tumorigenic breast cells (MCF10A).

Methods

EVs were isolated from TNBC cell lines and characterized by nanoparticle tracking analysis, Western blot, and transmission electron microscopy. MCF10A cells were treated with the isolated EVs and evaluated for cell proliferation and cytotoxicity to Docetaxel and Doxorubicin by the MTT and MTS assays, respectively. Gene and miRNA expression profiling was performed in the treated cells to determine expression changes that may be caused by EVs treatment.

Results

MCF10A cells treated with HCC1806-EVs (MCF10A/HCC1806-EVs) showed a significant increase in cell proliferation and resistance to the therapeutic agents tested. No significant effects were observed in the MCF10A cells treated with EVs derived from MDA-MB-231 cells. Gene and miRNA expression profiling revealed 138 genes and 70 miRNAs significantly differentially expressed among the MCF10A/HCC1806-EVs and the untreated MCF10A cells, affecting mostly the PI3K/AKT, MAPK, and HIF1A pathways.

Conclusion

EVs isolated from the HCC1806 TNBC cells are capable of inducing proliferation and drug resistance on the non-tumorigenic MCF10A breast cells, potentially mediated by changes in genes and miRNAs expression associated with cell proliferation, apoptosis, invasion, and migration.

Electronic supplementary material

The online version of this article (10.1007/s10549-018-4925-5) contains supplementary material, which is available to authorized users.

Intra-tumoral delivery of functional ID4 protein via PCL/maltodextrin nano-particle inhibits prostate cancer growth

ID4, a helix loop helix transcriptional regulator has emerged as a tumor suppressor in prostate cancer. Epigenetic silencing of ID4 promotes prostate cancer whereas ectopic expression in prostate cancer cell lines blocks cancer phenotype. To directly investigate the anti-tumor property, full length human recombinant ID4 encapsulated in biodegradable Polycaprolactone/Maltodextrin (PCL-MD) nano-carrier was delivered to LNCaP cells in which the native ID4 was stably silenced (LNCaP(-)ID4). The cellular uptake of ID4 resulted in increased apoptosis, decreased proliferation and colony formation. Intratumoral delivery of PCL-MD ID4 into growing LNCaP(-)ID4 tumors in SCID mice significantly reduced the tumor volume compared to the tumors treated with chemotherapeutic Docetaxel. The study supports the feasibility of using nano-carrier encapsulated ID4 protein as a therapeutic. Mechanistically, ID4 may assimilate multiple regulatory pathways for example epigenetic re-programming, integration of multiple AR co-regulators or signaling pathways resulting in tumor suppressor activity of ID4.

A Novel MPEG-PDLLA-PLL Copolymer for Docetaxel Delivery in Breast Cancer Therapy

Satisfactory drug loading capacity and stability are the two main factors that determine the anti-cancer performance. In general, the stability of the micelles is reduced when the drug loading (DL) is increased. Therefore, it was a challenge to have high drug loading capacity and good stability. In this study, we introduced a hydrophilic poly (L-Lysine) (PLL) segment with different molecular-weights into the monomethoxy poly (ethylene glycol)-poly (D, L-lactide) (MPEG-PDLLA) block copolymer to obtain a series of novel triblock MPEG-PDLLA-PLL copolymers. We found that the micelles formed by a specific MPEG2k-PDLLA4k-PLL1k copolymer could encapsulate docetaxel (DTX) with a satisfactory loading capacity of up to 20% (w/w) via the thin film hydration method, while the stability of drug loaded micellar formulation was still as good as that of micelles formed by MPEG2k-PDLLA1.7k with drug loading of 5% (w/w). The results from computer simulation study showed that compared with MPEG2k-PDLLA1.7k, the molecular chain of MPEG2k-PDLLA4k-PLL1k could form a more compact funnel-shaped structure when interacted with DTX. This structure favored keeping DTX encapsulated in the copolymer molecules, which improved the DL and stability of the nano-formulations. The in vitro and in vivo evaluation showed that the DTX loaded MPEG2k-PDLLA4k-PLL1k (DTX/MPEG2k-PDLLA4k-PLL1k) micelles exhibited more efficiency in tumor cell growth inhibition. In conclusion, the MPEG2k-PDLLA4k-PLL1k micelles were much more suitable than MPEG2k-PDLLA1.7k for DTX delivery, and then the novel nano-formulations showed better anti-tumor efficacy in breast cancer therapy.

Therapeutic potential of novel formulated forms of curcumin in the treatment of breast cancer by the targeting of cellular and physiological dysregulated pathways

Breast cancer is among the most important causes of cancer related death in women. There is a need for novel agents for targeting key signaling pathways to either improve the efficacy of the current therapy, or reduce toxicity. There is some evidence that curcumin may have antitumor activity in breast cancer. Several clinical trials have investigated its activity in patients with breast cancer, including a recent trial in breast cancer patients receiving radiotherapy, in whom it was shown that curcumin reduced the severity of radiation dermatitis, although it is associated with low bioavailability. Several approaches have been developed to increase its absorption rate (e.g., nano crystals, liposomes, polymers, and micelles) and co-delivery of curcumin with adjuvants as well as different conjugation to enhance its bioavailability. In particular, micro-emulsions is an option for transdermal curcumin delivery, which has been reported to increase its absorption. Lipid-based nano-micelles is another approach to enhance curcumin absorption via gastrointestinal tract, while polymer-based nano-formulations (e.g., poly D, L-lactic-co-glycolic [PLGA]) allows the release of curcumin at a sustained level. This review summarizes the current data of the therapeutic potential of novel formulations of curcumin with particular emphasis on recent preclinical and clinical studies in the treatment of breast cancer.

Significant effect of age on docetaxel pharmacokinetics in Japanese female breast cancer patients by using the population modeling approach

PURPOSE

Docetaxel is frequently used in the treatment of a wide variety of solid tumors, including breast cancer. The aim of this study is to obtain the population pharmacokinetic parameters of docetaxel in Japanese female patients with breast cancer.

METHODS

Blood samples from 24 patients were collected sequentially before and after docetaxel infusion. Genomic DNA was isolated from the peripheral blood and genotyped for the selected polymorphisms in the candidate genes of drug transporters and metabolizing enzymes. The influence of patient characteristics on the pharmacokinetics of docetaxel was evaluated using the nonlinear-mixed-effect modeling program, NONMEM. As a basis for comparison, the pharmacokinetics of another taxane paclitaxel in 41 separate female patients with breast cancer was calculated.

RESULTS

A two-compartment model adequately described the pharmacokinetic profiles of docetaxel. The population mean estimates of the total body clearance for patients aged 58 years or less and the central volume of distribution for docetaxel were 32.6 L/h and 5.77 L, respectively. In patients over 58 years, the clearance was 24 % higher than that in the younger patients. No influences of the genotypes examined were noted on the clearance of docetaxel. The clearance of paclitaxel was not affected by patient age.

CONCLUSIONS

Patients over the age of 58 years showed significantly higher clearance of docetaxel than that in patients aged 58 years or less. Since the clearance of paclitaxel was not affected by the age, it is possible that the pharmacokinetic mechanisms of docetaxel might be specifically affected by age in females.

Enhanced antitumor efficacy of folate targeted nanoparticles co-loaded with docetaxel and curcumin

BACKGROUND

The current study aimed to investigate whether the novel folate (FT) modified nanoparticles (NPs) co-loaded with docetaxel (DT) and curcumin (CU) (named as FT-NPs) could enhance the delivery efficiency to tumor compared with the NPs without FT (non-targeted NPs).

METHODS

FT-NPs were successfully formulated in this article. In vitro cytotoxic activity against A549 cells and in vivo antitumor activity of FT-NPs in S180 cell bearing mice were conducted. Cellular uptake test was used to evaluate uptake efficiency of FT-NPs. Histological observation was used to determine the lung security. Besides, the physical chemical properties such as stability, particle size, zeta potential, drug encapsulation efficiency, transmission electron microscopy (TEM) were also conducted.

RESULTS

FT-NPs exhibited stronger growth inhibition effects on A549 cells compared with non-targeted NPs, moreover, the novel FT-NPs indicated more effective antitumor efficacy in inhibiting tumor growth. Confocal laser scanning microscopy indicated that the uptake of FT-NPs was facilitated and effective. Histological observation meant that FT-NPs were biocompatible and appropriate for pulmonary administration.

CONCLUSION

These results confirmed that FT-NPs with relatively high drug loading capacity could effectively inhibit tumor growth and reduce toxicity. The novel FT-NPs could produce as an outstanding nanocarrier for the targeted treatment of cancers.

Lipid-coated gold nanocomposites for enhanced cancer therapy

The aim of the work reported here was to develop lipid-coated multifunctional nanocomposites composed of drugs and nanoparticles for use in cancer therapy. We incorporated thermosensitive phospholipids onto the surface of anisotropic gold nanoparticles (AuNPs) to further enhance drug delivery, with possible additional applications for in vivo imaging and photothermal cancer therapy. Lipid-coated nanohybrids loaded with the drug docetaxel (DTX) were prepared by a thin-film formation, hydration, and sonication method. Nanoparticles and their composites were characterized using particle-size analysis, zeta potential measurements, transmission electron microscopy, UV-visible spectroscopy, and reverse-phase high-performance liquid chromatography, demonstrating successful loading of DTX into the lipid bilayer on the surface of the gold nanoparticles. Initial in vitro studies using breast-cancer (MCF-7) and melanoma (B16F10) cell lines demonstrated that the drug-containing nanocomposites at equivalent drug concentrations caused significant cytotoxicity compared to free DTX. Differential flow cytometry analysis confirmed the improved cellular uptake of lipid-coated nanocomposites. Our preliminary results show that DTX-loaded anionic lipid-coated gold nanorod (AL_AuNR_DTX) and cationic lipid-coated gold nanoparticle (CL_AuNP_DTX) possess effective tumor cell-suppression abilities and can therefore be considered promising chemotherapeutic agents. Further evaluation of the therapeutic efficacy of these hybrid nanoparticles combined with external near-infrared photothermal treatment is warranted to assess their synergistic anticancer actions and potential bioimaging applications.

Efficacy and safety of docetaxel for advanced non-small-cell lung cancer: a meta-analysis of Phase III randomized controlled trials

Background

Several clinical trials have performed risk–benefit analyses comparing docetaxel and pemetrexed or docetaxel and vinca alkaloid, but the efficacy and safety remain uncertain. The aim was to conduct a meta-analysis to compare the efficacy and safety of docetaxel and pemetrexed or docetaxel and vinca alkaloid for non-small-cell lung cancer.

Methods

This meta-analysis of Phase III randomized controlled trials was performed after searching PubMed, Embase, the Cochrane Library, and the ISI Web of Knowledge for randomized controlled trials. Outcome analyses were overall survival, progression-free survival, and overall response rate with 95% confidence intervals and major grade 3/4 toxicity.

Results

Seven eligible trials involving 2,080 patients were retrieved for analysis. Docetaxel enhanced progression-free survival and overall response rate compared with vinca alkaloid as first-line treatment (P<0.05). However, there was no difference between docetaxel and pemetrexed as both first-line and second-line treatment (P>0.05). With regard to the grade 3/4 toxicity, compared with pemetrexed, docetaxel led to higher neutropenia and febrile neutropenia (P<0.05), but there was no difference in non-hematological toxicity (P>0.05). Docetaxel led to a lower rate of anemia as first-line treatment (P<0.05). Moreover, docetaxel caused less grade 3/4 hematological and non-hematological toxicity compared with vinca alkaloid.

Conclusion

Docetaxel leads to a better result than vinca alkaloid in effectiveness and safety on patients with advanced non-small-cell lung cancer as first-line therapy. Docetaxel also causes lower toxicity as second-line therapy compared with vinca alkaloid. However, the differences in efficacy and safety between docetaxel and pemetrexed are not obvious. Further clinical study with more details, such as sex, age, histology, and so on, should be considered for illustrating the differences between these two drugs.

Drug delivery design for intravenous route with integrated physicochemistry, pharmacokinetics and pharmacodynamics: illustration with the case of taxane therapeutics

This review is aimed at combining the published data on taxane formulations into a generalized Drug Delivery approach, starting from the physicochemistry and assessing its relationships with the pharmacokinetics, the biodistribution and the pharmacodynamics. Owing to the number and variety of taxane formulation designs, we considered this class of cytotoxic anticancer agents of particular interest to illustrate the concepts attached to this approach. According to the history of taxane development, we propose a classification as (i) "surfactant-based formulations" first generation, (ii) "surfactant-free formulations" second generation and (iii) "modulated pharmacokinetics drug delivery systems" third generation. Since our objective was to make the link between (i) the physicochemistry of the drug and carrier and (ii) the efficacy and safety of the drug in preclinical animal models and (iii) in human, we focused on the drug delivery technologies that were tested in clinic.

The relationship of polymorphisms in ABCC2 and SLCO1B3 with docetaxel pharmacokinetics and neutropenia: CALGB 60805 (Alliance)

Docetaxel-related neutropenia was associated with polymorphisms in the drug transporters ABCC2 and SLCO1B3 in Japanese cancer patients. We hypothesized that this association is because of reduced docetaxel clearance, associated with polymorphisms in those genes. We studied 64 US cancer patients who received a single cycle of 75 mg/m of docetaxel monotherapy. We found that the ABCC2 polymorphism at rs-12762549 trended to show a relationship with reduced docetaxel clearance (P=0.048), but not with neutropenia. There was no significant association of the SLCO1B3 polymorphisms with docetaxel clearance or neutropenia. We conclude that the relationship between docetaxel-associated neutropenia and polymorphisms in drug transporters identified in Japanese patients was not confirmed in this cohort of US cancer patients.

A biocompatible in vivo ligation reaction and its application for noninvasive bioluminescent imaging of protease activity in living mice

The discovery of biocompatible reactions had a tremendous impact on chemical biology, allowing the study of numerous biological processes directly in complex systems. However, despite the fact that multiple biocompatible reactions have been developed in the past decade, very few work well in living mice. Here we report that D-cysteine and 2-cyanobenzothiazoles can selectively react with each other in vivo to generate a luciferin substrate for firefly luciferase. The success of this "split luciferin" ligation reaction has important implications for both in vivo imaging and biocompatible labeling strategies. First, the production of a luciferin substrate can be visualized in a live mouse by bioluminescence imaging (BLI) and furthermore allows interrogation of targeted tissues using a "caged" luciferin approach. We therefore applied this reaction to the real-time noninvasive imaging of apoptosis associated with caspase 3/7. Caspase-dependent release of free D-cysteine from the caspase 3/7 peptide substrate Asp-Glu-Val-Asp-D-Cys (DEVD-(D-Cys)) allowed selective reaction with 6-amino-2-cyanobenzothiazole (NH(2)-CBT) in vivo to form 6-amino-D-luciferin with subsequent light emission from luciferase. Importantly, this strategy was found to be superior to the commercially available DEVD-aminoluciferin substrate for imaging of caspase 3/7 activity. Moreover, the split luciferin approach enables the modular construction of bioluminogenic sensors, where either or both reaction partners could be caged to report on multiple biological events. Lastly, the luciferin ligation reaction is 3 orders of magnitude faster than Staudinger ligation, suggesting further applications for both bioluminescence and specific molecular targeting in vivo.

[[¹¹C]choline as a pharmacodynamic marker for docetaxel therapy. Response assessment in a LNCaP prostate cancer xenograft mouse model]

The AIM of this study was to determine whether [¹¹C]choline can be used for docetaxel therapy response assessment in a LNCaP-prostate cancer xenograft mouse model using [¹¹C]choline small-animal PET/CT.

ANIMALS, METHODS

The androgen-dependent human prostate cancer cell line LNCaP was implanted subcutaneously into the left flanks of 17 SCID-mice, 12.5 mg testosterone platelets were implanted in the neck wrinkle. All mice were injected 4-6 weeks after xenograft implantation with 37 MBq [¹¹C]choline via the tail vein. Dynamic imaging was performed for 60 minutes with a small-animal PET/CT scanner. After the first [¹¹C]choline PET/CT imaging 8 mice were subsequently injected intravenously with docetaxel twice (days 1 and 5) at a dose of 3 mg/kg body weight. 8 mice were treated with PBS as a control. [¹¹C]choline PET/CT imaging was performed on day 7, 14 and 21 after treatment. Image analysis was performed using tumor/muscle (T/M) ratios (ROI(T)/ROI(M) = T/M ratio).

RESULTS

All LNCaP tumours could be visualized by [¹¹C]choline PET/CT. Before treatment the mean T/M ratio was 2.0 ± 0.2 in the docetaxel-treated group and 1.9 ± 0.2 in the control group (p = 0.837). There was a reduction in the mean [¹¹C]choline uptake after docetaxel treatment of the tumours of the LNCaP cell line as early as 1 week after initiation of therapy (T/M(mean) ratio 1.5 ± 0.2 after one week, 1.3 ± 0.2 after 2 weeks and 1.4 ± 0.2 after 3 weeks). There was no decrease in [¹¹C]choline uptake in the control group.

CONCLUSION

Our results show that [¹¹C]choline has the potential for use in the early monitoring of the therapeutic effect of docetaxel in a LNCaP prostate cancer xenograft animal model.

Enhanced docetaxel-mediated cytotoxicity in human prostate cancer cells through knockdown of cofilin-1 by carbon nanohorn delivered siRNA

We synthesized a non-viral delivery system (f-CNH3) for small interfering RNA (siRNA) by anchoring a fourth-generation polyamidoamine dendrimer (G4-PAMAM) to carbon nanohorns (CNHs). Using this new compound, we delivered a specific siRNA designed to knockdown cofilin-1, a key protein in the regulation of cellular cytoskeleton, to human prostate cancer (PCa) cells. The carbon nanohorn (CNH) derivative was able to bind siRNA and release it in the presence of an excess of the polyanion heparin. Moreover, this hybrid nanomaterial protected the siRNA from RNAse-mediated degradation. Synthetic siRNA delivered to PCa cells by f-CNH3 decreased the cofilin-1 mRNA and protein levels to about 20% of control values. Docetaxel, the drug of choice for the treatment of PCa, produced a concentration-dependent activation of caspase-3, an increase in cell death assessed by lactate dehydrogenase release to the culture medium, cell cycle arrest and inhibition of tumor cell proliferation. All of these toxic effects were potentiated when cofilin-1 was down regulated in these cells by a siRNA delivered by the nanoparticle. This suggests that knocking down certain proteins involved in cancer cell survival and/or proliferation may potentiate the cytotoxic actions of anticancer drugs and it might be a new therapeutic approach to treat tumors.

Combination effects of docetaxel and Doxorubicin in hormone-refractory prostate cancer cells

Combination effects of docetaxel (DOC) and doxorubicin (DOX) were investigated in prostate cancer cells (PC3 and DU145). Combination indices (CIs) were determined using the unified theory in various concentrations and mixing ratios (synergy: CI < 0.9, additivity: 0.9 < CI < 1.1, and antagonism: CI > 1.1). DOC showed a biphasic cytotoxicity pattern with the half maximal inhibitory concentration (IC50) at the picomolar range for PC3 (0.598 nM) and DU145 (0.469 nM), following 72 h drug exposure. The IC50s of DOX were 908 nM and 343 nM for PC3 and DU145, respectively. Strong synergy was seen when PC3 was treated with DOC at concentrations lower than its IC50 values (0.125~0.5 nM) plus DOX (2~8 times IC50). Equipotent drug combination treatments (7 × 7) revealed that the DOC/DOX combination leads to high synergy and effective cell death only in a narrow concentration range in DU145. This study provides a convenient method to predict multiple drug combination effects by the estimated CI values as well as cell viability data. The proposed DOC/DOX mixing ratios can be used to design combination drug cocktails or delivery systems to improve chemotherapy for cancer patients.

GADD45 proteins: central players in tumorigenesis

The Growth Arrest and DNA Damage-inducible 45 (GADD45) proteins have been implicated in regulation of many cellular functions including DNA repair, cell cycle control, senescence and genotoxic stress. However, the pro-apoptotic activities have also positioned GADD45 as an essential player in oncogenesis. Emerging functional evidence implies that GADD45 proteins serve as tumor suppressors in response to diverse stimuli, connecting multiple cell signaling modules. Defects in the GADD45 pathway can be related to the initiation and progression of malignancies. Moreover, induction of GADD45 expression is an essential step for mediating anti-cancer activity of multiple chemotherapeutic drugs and the absence of GADD45 might abrogate their effects in cancer cells. In this review, we present a comprehensive discussion of the functions of GADD45 proteins, linking their regulation to effectors of cell cycle arrest, DNA repair and apoptosis. The ramifications regarding their roles as essential and central players in tumor growth suppression are also examined. We also extensively review recent literature to clarify how different chemotherapeutic drugs induce GADD45 gene expression and how its up-regulation and interaction with different molecular partners may benefit cancer chemotherapy and facilitate novel drug discovery.

Effects of herbal products on the metabolism and transport of anticancer agents

IMPORTANCE OF THE FIELD

Cancer patients on chemotherapy treatment often seek herbal therapies and this may alter the clearance of anticancer drugs.

AREAS COVERED IN THIS REVIEW

Many anticancer drugs are metabolized by CYPs and are substrates of P-glycoprotein, breast cancer resistance protein and multi-drug resistance proteins. CYPs and drug transporters are subject to inhibition and/or induction by the herbal medicines used by cancer patients and the metabolism and pharmacokinetics of anticancer agents may be altered by herbal products. There are increased reports on the interaction of herbal medicines with anticancer agents. A clinical study in cancer patients reported that treatment of St John's wort at 900 mg/day orally for 18 days decreased the plasma levels of the active metabolite of irinotecan, SN-38, by 42%. In healthy subjects, treatment with St John's wort for 2 weeks significantly decreased the systemic exposure of imatinib by 32%. Induction and/or inhibition of CYPs and transporters is considered an important mechanism for these interactions.

WHAT THE READER WILL GAIN

Potential interactions of herbal medicines with anticancer agents have become a safety concern in cancer chemotherapy.

TAKE HOME MESSAGE

Further studies are warranted to investigate the efficacy and safety profiles of herbal medicines commonly used by cancer patients.

[11C]Choline as pharmacodynamic marker for therapy response assessment in a prostate cancer xenograft model

PURPOSE

[(11)C]Choline has been established as a PET tracer for imaging prostate cancer. The aim of this study was to determine whether [(11)C]choline can be used for monitoring the effects of therapy in a prostate cancer mouse xenograft model.

METHODS

The androgen-independent human prostate cancer cell line PC-3 was implanted subcutaneously into the flanks of 13 NMRI (nu/nu) mice. All mice were injected 4-6 weeks after xenograft implantation with 37 MBq [(11)C]choline via a tail vein. Dynamic imaging was performed for 60 min with a small-animal PET/CT scanner (Siemens Medical Solutions). Six mice were subsequently injected intravenously with docetaxel twice (days 1 and 5) at a dose of 3 mg/kg body weight. Seven mice were treated with PBS as a control. [(11)C]Choline imaging was performed prior to and 1, 2 and 3 weeks after treatment. To determine choline uptake the images were analysed in terms of tumour-to-muscle (T/M) ratios. Every week the size of the implanted tumour was determined with a sliding calliper.

RESULTS

The PC-3 tumours could be visualized by [(11)C]choline PET. Before treatment the T/M(mean) ratio was 1.6+/-0.5 in the control group and 1.8+/-0.4 in the docetaxel-treated group (p=0.65). There was a reduction in the mean [(11)C]choline uptake after docetaxel treatment as early as 1 week after initiation of therapy (T/M ratio 1.8+/-0.4 before treatment, 0.9+/-0.3 after 1 week, 1.1+/-0.3 after 2 weeks and 0.8+/-0.2 after 3 weeks). There were no decrease in [(11)C]choline uptake in the control group following treatment (T/M ratio 1.6+/-0.5 before treatment, 1.7+/-0.4 after 1 week, 1.8+/-0.7 after 2 weeks and 1.7+/-0.4 after 3 weeks). For analysis of the dynamic data, a generalized estimation equation model revealed a significant decrease in the T/M(dyn) ratios 1 week after docetaxel treatment, and the ratio remained at that level through week 3 (mean change -0.93+/-0.24, p<0.001, after 1 week; -0.78+/-0.21, p<0.001, after 2 weeks; -1.08+/-0.26, p<0.001, after 3 weeks). In the control group there was no significant decrease in the T/M(dyn) ratios (mean change 0.085+/-0.39, p=0.83, after 1 week; 0.31+/-0.48, p=0.52, after 2 weeks; 0.11+/-0.30, p=0.72, after 3 weeks). Metabolic changes occurred 1 week after therapy and preceded morphological changes of tumour size during therapy.

CONCLUSION

Our results demonstrate that [(11)C]choline has the potential for use in the early monitoring of the therapeutic effect of docetaxel in a prostate cancer xenograft animal model. The results also indicate that PET with radioactively labelled choline derivatives might be a useful tool for monitoring responses to taxane-based chemotherapy in patients with advanced prostate cancer.

Pharmacokinetics of anti-cancer drugs used in breast cancer chemotherapy

Pharmacokinetics of anticancer drugs used in breast cancer therapy are well established. This chapter reviews preclinical and clinical pharmacokinetics of the following drugs: cyclophosphamide, docetaxel, doxorubicin, 5-fluorouracil, methotrexate and tamoxifen. The absorption, distribution, metabolism and elimination of drugs are discussed in the context of breast cancer. The effect of age and menopause status on drug pharmacokinetics is evaluated. The important role of pharmacokinetic-pharmacodynamic modeling in understanding the phenomenon of chemo fog, memory deficit in breast cancer chemotherapy, is explored.

Methylation-mediated repression of GADD45alpha in prostate cancer and its role as a potential therapeutic target

Defects in apoptotic pathway contribute to uncontrolled proliferation of cancer cells and confer resistance to chemotherapy. Growth arrest and DNA damage inducible, alpha (GADD45alpha) is up-regulated on docetaxel treatment and may contribute to docetaxel-mediated cytotoxicity. We examined the mechanism of regulation of GADD45alpha in prostate cancer cells and the effect of its up-regulation on sensitivity to docetaxel chemotherapy. Expression of GADD45alpha in PC3 cells was higher than that in Du145 and LNCaP cells (17- and 12-fold, respectively; P < 0.05). Although the proximal promoter region was unmethylated in all three cell lines, methylation of a 4 CpG region upstream of the proximal promoter correlated inversely with gene expression levels. Methylation was reversed by treatment of Du145 and LNCaP cells with DNA methyltransferase inhibitors, leading to reactivation of GADD45alpha expression in these cells. The 5' 4 CpG region was also frequently methylated in prostate cancer tissues. Methylation of this region correlated inversely with gene expression in prostate cancer and benign prostate tissues. The methyl binding protein MeCP2 was associated with the methylated 4 CpGs in Du145 cells, and knockdown of MeCP2 in these cells (Du145 MeCP2(-)) led to a significantly increased expression of GADD45alpha (3-fold; P = 0.035) without affecting the methylation status of the gene. Enhanced sensitivity to docetaxel was observed by up-regulation of GADD45alpha in Du145 cells by recombinant expression of GADD45alpha or pretreatment with 5-azacytidine. Our results show that GADD45alpha is epigenetically repressed and is a potential target for treatment of prostate cancer.

A monolayer study on interactions of docetaxel with model lipid membranes

Docetaxel (DCT) is an antineoplastic drug for the treatment of a wide spectrum of cancers. DCT surface properties as well as miscibility studies with l-alpha-dipalmitoyl phosphatidylcholine (DPPC), which constitutes the main component of biological membranes, are comprehensively described in this contribution. Penetration studies have revealed that when DCT is injected under DPPC monolayers compressed to different surface pressures, it penetrates into the lipid monolayer promoting an increase in the surface pressure. DCT is a surface active molecule able to decrease the surface tension of water and to form insoluble films when spread on aqueous subphases. The maximum surface pressure reached after compression of a DCT Langmuir film was 13 mN/m. Miscibility of DPPC and DCT in Langmuir films has been studied by means of thermodynamic properties as well as by Brewster angle microscopy (BAM) analysis of the mixed films at the air-water interface, concluding that DPPC and DCT are miscible and they form non-ideally mixed monolayers at the air-water interface. Helmholtz energies of mixing revealed that no phase separation occurs. In addition, Helmholtz energies of mixing become more negative with decreasing areas per molecule, which suggests that the stability of the mixed monolayers increases as the monolayers become more condensed. Compressibility values together with BAM images indicate that DCT has a fluidizing effect on DPPC monolayers.

A Phase I trial of weekly docetaxel and topotecan for solid tumors

BACKGROUND/AIMS

Topotecan and docetaxel are active agents in the treatment of various malignant diseases. Both drugs cause dose-limiting hematologic toxicity. This study defines the maximum tolerated dose (MTD) and dose-limiting toxicity of weekly topotecan when administered in combination with docetaxel 25 mg/m(2) given day 1, 8,15 every 28 days.

METHODS

Thirteen patients were enrolled. Median age was 62 years. Majority of the patients had lung cancer.

RESULTS

The maximum tolerated dose was docetaxel 25 mg/m(2) and topotecan 3 mg/m(2) administered weekly. Dose-limiting toxicity was febrile neutropenia. Eight patients developed at least grade 3 neutropenia in all cycles. Non-hematologic toxicities were mild. No objective responses were noted. Two patients with non-small cell lung cancer had stable disease as a best response.

CONCLUSION

Combination docetaxel and topotecan given weekly is tolerable. The recommended phase II dose is docetaxel 25 mg/m(2) and topotecan 3 mg/m(2) day 1, 8, 15 every 28 days.

The establishment of two paclitaxel-resistant prostate cancer cell lines and the mechanisms of paclitaxel resistance with two cell lines

BACKGROUND

Although paclitaxel is used for hormone-resistant prostate cancer, relapse definitely occurs later. Details of the molecular mechanism responsible for paclitaxel- resistance remain unclear.

METHODS

We established paclitaxel-resistant cells, DU145-TxR and PC-3-TxR from parent DU145 and PC-3. To characterize these cells, we examined cross-resistance to other anticancer drugs. Expression of several potential genes that had been related to drug-resistance was compared with parent cells by RT-PCR and Western blotting. Methylation analysis of multiple drug resistance (MDR1) promoter was carried out using bisulfite-modified DNA from cell lines. Knockdown experiments using small interfering RNA (siRNA) were also performed to confirm responsibility of drug-resistance. Finally, cDNA microarray was performed to quantify gene expression in PC-3 and PC-3-TxR cells.

RESULTS

The IC(50) for paclitaxel in DU145-TxR and PC-3-TxR was 34.0- and 43.4-fold higher than that in both parent cells, respectively. Both cells showed cross-resistance to some drugs, but not to VP-16 and cisplatin. Methylation analysis revealed that methylated CpG sites of MDR1 promoter in DU145 and PC-3 cells were demethylated in DU145-TxR cells, but not in PC-3-TxR cells. Knockdown of P-glycoprotein (P-gp), which was up-regulated in resistant cells, by MDR-1 siRNA restored paclitaxel sensitivity in DU145-TxR but not in PC-3-TxR, indicating that up-regulation of P-gp was not always main cause of paclitaxel-resistance. Microarray analysis identified 201 (1.34%) up-regulated genes and 218 (1.45%) out of screened genes in PC-3-TxR.

CONCLUSIONS

Our data will provide molecular mechanisms of paclitaxel-resistance and be useful for screening target genes to diagnose paclitaxel sensitivity.

A Comparison of the Pharmacokinetics and Pharmacodynamics of Docetaxel between African-American and Caucasian Cancer Patients: CALGB 9871

PURPOSE

Increased clearance of drugs, such as oral cyclosporine, that are CYP3A and/or ABCB1 (P-gp/MDR1) substrates was reported in African-American compared with Caucasian patients. We hypothesized that the pharmacokinetics and pharmacodynamics of docetaxel, an i.v. administered cytotoxic and substrate for CYP3A4, CYP3A5, and ABCB1, would differ between African-American and Caucasian patients.

EXPERIMENTAL DESIGN

We investigated population pharmacokinetics and pharmacodynamics and the pharmacogenetics of CYP3A4, CYP3A5, and ABCB1 in African-American and Caucasian cancer patients who received docetaxel 75 or 100 mg/m(2) as a 1-h i.v. infusion. Plasma docetaxel concentrations were measured by high-performance liquid chromatography. Clinical toxicity and absolute neutrophil count (ANC) were monitored on days 8, 15, and 22 postadministration of docetaxel. Using a limited sampling strategy and nonlinear mixed-effects modeling, each patient's docetaxel clearance was estimated. Genotyping for known polymorphisms in CYP3A4, CYP3A5, and ABCB1 was done.

RESULTS

We enrolled 109 patients: 40 African-Americans (26 males; 14 females), with a median age of 61 years (range, 29-73), and 69 Caucasians (43 males; 26 females), with a median age of 63 years (range, 38-81). There was no difference in the geometric mean docetaxel clearance between African-American patients [40.3 L/h; 95% confidence interval (95% CI), 19.3-84.1] and Caucasian patients (41.8 L/h; 95% CI, 22.0-79.7; P = 0.6). We observed no difference between African-American and Caucasian patients in the percentage decrease in ANC nor were docetaxel pharmacokinetic parameters related to the genotypes studied.

CONCLUSIONS

Docetaxel clearance and its associated myelosuppression were similar in African-American and Caucasian cancer patients.