Gemcitabine in metastatic breast cancer

Ganoderma lucidum spores-derived particulate β-glucan treatment improves antitumor response by regulating myeloid-derived suppressor cells in triple-negative breast cancer

Granular β-1,3-glucan extracted from the wall of Ganoderma lucidum spores, named GPG, is a bioregulator. In this study, we investigated the structural, thermal, and other physical properties of GPG. We determined whether GPG ameliorated immunosuppression caused by Gemcitabine (GEM) chemotherapy. Triple-negative breast cancer mice with GPG combined with GEM treatment had reduced tumor burdens. In addition, GEM treatment alone altered the tumor microenvironment(TME), including a reduction in antitumor T cells and a rise in myeloid-derived suppressor cells (MDSC) and regulatory T cells (Tregs). However, combined GPG treatment reversed the tumor immunosuppressive microenvironment induced by GEM. GPG inhibited bone marrow (BM)-derived MDSC differentiation and reversed MDSC expansion induced by conditioned medium (CM) in GEM-treated E0771 cells through a Dectin-1 pathway. In addition, GPG downgraded PD-L1 and IDO1 expression on MDSC while boosting MHC-II, CD86, TNF-α, and IL-6 expression. In conclusion, this study demonstrated that GPG could alleviate the adverse effects induced by GEM chemotherapy by regulating TME.

Natural products derived from medicinal plants and microbes might act as a game-changer in breast cancer: a comprehensive review of preclinical and clinical studies

Breast cancer (BC) is the most prevalent neoplasm among women. Genetic and environmental factors lead to BC development and on this basis, several preventive - screening and therapeutic interventions have been developed. Hormones, both in the form of endogenous hormonal signaling or hormonal contraceptives, play an important role in BC pathogenesis and progression. On top of these, breast microbiota includes both species with an immunomodulatory activity enhancing the host's response against cancer cells and species producing proinflammatory cytokines associated with BC development. Identification of novel multitargeted therapeutic agents with poly-pharmacological potential is a dire need to combat advanced and metastatic BC. A growing body of research has emphasized the potential of natural compounds derived from medicinal plants and microbial species as complementary BC treatment regimens, including dietary supplements and probiotics. In particular, extracts from plants such as Artemisia monosperma Delile, Origanum dayi Post, Urtica membranacea Poir. ex Savigny, Krameria lappacea (Dombey) Burdet & B.B. Simpson and metabolites extracted from microbes such as Deinococcus radiodurans and Streptomycetes strains as well as probiotics like Bacillus coagulans and Lactobacillus brevis MK05 have exhibited antitumor effects in the form of antiproliferative and cytotoxic activity, increase in tumors' chemosensitivity, antioxidant activity and modulation of BC - associated molecular pathways. Further, bioactive compounds like 3,3'-diindolylmethane, epigallocatechin gallate, genistein, rutin, resveratrol, lycopene, sulforaphane, silibinin, rosmarinic acid, and shikonin are of special interest for the researchers and clinicians because these natural agents have multimodal action and act via multiple ways in managing the BC and most of these agents are regularly available in our food and fruit diets. Evidence from clinical trials suggests that such products had major potential in enhancing the effectiveness of conventional antitumor agents and decreasing their side effects. We here provide a comprehensive review of the therapeutic effects and mechanistic underpinnings of medicinal plants and microbial metabolites in BC management. The future perspectives on the translation of these findings to the personalized treatment of BC are provided and discussed.

In Silico Mixed Ligand/Structure-Based Design of New CDK-1/PARP-1 Dual Inhibitors as Anti-Breast Cancer Agents

CDK-1 and PARP-1 play crucial roles in breast cancer progression. Compounds acting as CDK-1 and/or PARP-1 inhibitors can induct cell death in breast cancer with a selective synthetic lethality mechanism. A mixed treatment by means of CDK-1 and PARP-1 inhibitors resulted in radical breast cancer cell growth reduction. Inhibitors with a dual target mechanism of action could arrest cancer progression by simultaneously blocking the DNA repair mechanism and cell cycle, resulting in advantageous monotherapy. To this aim, in the present work, we identified compound 645656 with a significant affinity for both CDK-1 and PARP-1 by a mixed ligand- and structure-based virtual screening protocol. The Biotarget Predictor Tool was used at first in a Multitarget mode to filter the large National Cancer Institute (NCI) database. Then, hierarchical docking studies were performed to further screen the compounds and evaluate the ligands binding mode, whose putative dual-target mechanism of action was investigated through the correlation between the antiproliferative activity data and the target proteins' (CDK-1 and PARP-1) expression pattern. Finally, a Molecular Dynamics Simulation confirmed the high stability of the most effective selected compound 645656 in complex with both PARP-1 and CDK-1.

Synthesis and anticancer evaluation of acetylated-lysine conjugated gemcitabine prodrugs

Gemcitabine is an antimetabolite drug approved for the treatment of various cancers. However, its use is limited due to several issues such as stability, toxicity and drug resistance. Herein, we present the design and synthesis of a series of gemcitabine prodrugs with modifications on the 4-N-amino group by employing an acetylated l- or d-lysine moiety masked by different substitutions. Prodrugs 1-3 and 6-8 showed up to 2.4 times greater anticancer activity than gemcitabine in A549 lung cells, while they exhibited potent activity against BxPC-3 pancreatic cells with IC50 values in the range of 7-40 nM. Moreover, prodrugs 2-3 and 7-8 were found to be less potent against CTSL low expression Caco-2 cells and at least 69-fold less toxic towards human normal HEK-293T cells compared to gemcitabine, leading to improved selectivity and safety profiles. Further stability studies showed that representative prodrugs 2 and 7 exhibited enhanced metabolic stability in human plasma, human liver microsomes and cytidine deaminase. Prodrug 1 can be cleaved by tumor cell-enriched CTSL to release parent drug gemcitabine. Overall, these results demonstrated that acetylated lysine conjugated gemcitabine prodrugs could serve as promising leads for further evaluation as new anticancer drugs.

Exploring the Inclusion Complex of an Anticancer Drug with β-Cyclodextrin for Reducing Cytotoxicity Toward the Normal Human Cell Line by an Experimental and Computational Approach

The toxicity of any drug against normal cells is a health hazard for all humans. At present, health and disease researchers from all over the world are trying to synthesize designer drugs with diminished toxicity and side effects. The purpose of the present study is to enhance the bioavailability and biocompatibility of gemcitabine (GEM) by decreasing its toxicity and reducing deamination during drug delivery by incorporating it inside the hydrophobic cavity of β-cyclodextrin (β-CD) without affecting the drug ability of the parent compound (GEM). The newly synthesized inclusion complex (IC) was characterized by different physical and spectroscopic techniques, thereby confirming the successful incorporation of the GEM molecule into the nanocage of β-CD. The molecular docking study revealed the orientation of the GEM molecule into the β-CD cavity (-5.40 kcal/mol) to be stably posed for ligand binding. Photostability studies confirmed that the inclusion of GEM using β-CD could lead to better stabilization of GEM (≥96%) for further optical and clinical applications. IC (GEM-β-CD) and GEM exhibited effective antibacterial and antiproliferative activities without being metabolized in a dose-dependent manner. The CT-DNA analysis showed sufficiently strong IC (GEM-β-CD) binding (Ka = 8.1575 × 1010), and this interaction suggests that IC (GEM-β-CD) may possibly exert its biological effects by targeting nucleic acids in the host cell. The newly synthesized biologically active IC (GEM-β-CD), a derivative of GEM, has pharmaceutical development potentiality.

Small molecule-mediated targeting of microRNAs for drug discovery: Experiments, computational techniques, and disease implications

Small molecules have been providing medical breakthroughs for human diseases for more than a century. Recently, identifying small molecule inhibitors that target microRNAs (miRNAs) has gained importance, despite the challenges posed by labour-intensive screening experiments and the significant efforts required for medicinal chemistry optimization. Numerous experimentally-verified cases have demonstrated the potential of miRNA-targeted small molecule inhibitors for disease treatment. This new approach is grounded in their posttranscriptional regulation of the expression of disease-associated genes. Reversing dysregulated gene expression using this mechanism may help control dysfunctional pathways. Furthermore, the ongoing improvement of algorithms has allowed for the integration of computational strategies built on top of laboratory-based data, facilitating a more precise and rational design and discovery of lead compounds. To complement the use of extensive pharmacogenomics data in prioritising potential drugs, our previous work introduced a computational approach based on only molecular sequences. Moreover, various computational tools for predicting molecular interactions in biological networks using similarity-based inference techniques have been accumulated in established studies. However, there are a limited number of comprehensive reviews covering both computational and experimental drug discovery processes. In this review, we outline a cohesive overview of both biological and computational applications in miRNA-targeted drug discovery, along with their disease implications and clinical significance. Finally, utilizing drug-target interaction (DTIs) data from DrugBank, we showcase the effectiveness of deep learning for obtaining the physicochemical characterization of DTIs.

Colistin Crosslinked Gemcitabine Micelles to Eliminate Tumor Drug Resistance Caused by Intratumoral Microorganisms

In the tumor microenvironment, there exist microorganisms that metabolize anticancer drugs, leading to chemotherapy failure. To solve this problem, herein, we develop antibiotic and anticancer drug co-delivery micelles, termed colistin crosslinked gemcitabine micelle (CCGM). A self-immolative linker enables colistin and gemcitabine to be released on demand without affecting their antibacterial and anticancer effects. Once CCGM is delivered to the tumor microenvironment, intracellular glutathione triggers the release of colistin and gemcitabine, inhibiting the growth of microbes in the tumor, thus eliminating the microbe-induced drug resistance of tumor.

Design, synthesis and antitumor activity study of a gemcitabine prodrug conjugated with a HDAC6 inhibitor

Gemcitabine, as a first-line antitumor drug, has attracted extensive attention. However the occurrence of drug resistance limits its clinical utilization. In this paper, a gemcitabine prodrug GZ was designed and synthesized by conjugation of gemcitabine with a newly reported HDAC6 selective inhibitor pentadecanoic acid. GZ displayed high cytotoxicity to nine cancer cell lines with IC₅₀ values in the low micromolar range. In vivo, GZ displayed superior antitumor activity to gemcitabine in a 4T1 tumor xenograft model without obvious pathological damage to important organs of mice. Our study showed that compound GZ is a potential gemcitabine prodrug, which is worthy of further antitumor activity exploration.

Two-Photon Photodynamic Therapy Targeting Cancers with Low Carboxylesterase 2 Activity Guided by Ratiometric Fluorescence

Human carboxylesterase 2 (hCES2) converts anticancer prodrugs, such as irinotecan, into their active metabolites via phase I drug metabolism. Owing to interindividual variability, hCES2 serves as a predictive marker of patient response to hCES2-activated prodrug-based therapy, whereby a low intratumoral hCES2 activity leads to therapeutic resistance. Despite the ability to identify nonresponders, effective treatments for resistant patients are needed. Clinically approved photodynamic therapy is an attractive alternative for irinotecan-resistant patients. Here, we describe the application of our hCES2-selective small-molecule ratiometric fluorescent chemosensor, Benz-AP, as a single theranostic agent given its discovered functionality as a photosensitizer. Benz-AP produces singlet oxygen and induces photocytotoxicity in cancer cells in a strong negative correlation with hCES2 activity. Two-photon excitation of Benz-AP produces fluorescence, singlet oxygen, and photocytotoxicity in tumor spheroids. Overall, Benz-AP serves as a novel theranostic agent with selective photocytotoxicity in hCES2-prodrug resistant cancer cells, making Benz-AP a promising agent for in vivo applications.

Recent Development of Prodrugs of Gemcitabine

Gemcitabine is a nucleoside analog that has been used widely as an anticancer drug for the treatment of a variety of conditions, including ovarian, bladder, non-small-cell lung, pancreatic, and breast cancer. However, enzymatic deamination, fast systemic clearance, and the emergence of chemoresistance have limited its efficacy. Different prodrug strategies have been explored in recent years, seeking to obtain better pharmacokinetic properties, efficacy, and safety. Different drug delivery strategies have also been employed, seeking to transform gemcitabine into a targeted medicine. This review will provide an overview of the recent developments in gemcitabine prodrugs and their effectiveness in treating cancerous tumors.

Classes of therapeutics to amplify the immune response

PURPOSE

Conventional chemotherapies are a mainstay for metastatic breast cancers, though durable response is rare. Immunotherapies promise long-term responses thorough immune activation but have been underwhelming in breast cancer relative to other cancer types. Here, we review the mechanisms of existing strategies including chemotherapies and how they may cause breast cancers to become immunogenic to identify potential biomarkers for combinations of conventional and immunotherapies.

CONCLUSION

Mechanistic considerations should inform biomarker development and patient selection for therapeutic combinations of drugs to combine with immune-checkpoint inhibitors.

Small Molecular Gemcitabine Prodrugs for Cancer Therapy

Gemcitabine as a pyrimidine nucleoside analog anticancer drug has high efficacy for a broad spectrum of solid tumors. Gemcitabine is activated within tumor cells by sequential phosphorylation carried out by deoxycytidine kinase to mono-, di-, and triphosphate nucleotides with the last one as the active form. But the instability, drug resistance and toxicity severely limited its utilization in clinics. In the field of medicinal chemistry, prodrugs have proven to be a very effective means for elevating drug stability and decrease undesirable side effects including the nucleoside anticancer drug such as gemcitabine. Many works have been accomplished in design and synthesis of gemcitabine prodrugs, majority of which were summarized in this review.

A Pharmacokinetic and Pharmacodynamic Evaluation of the Anti-Hepatocellular Carcinoma Compound 4-N-Carbobenzoxy-gemcitabine (Cbz-dFdC)

Gemcitabine (dFdC) demonstrates significant effectiveness against solid tumors in vitro and in vivo; however, its clinical application is limited because it tends to easily undergo deamination metabolism. Therefore, we synthesized 4-N-carbobenzoxy-gemcitabine (Cbz-dFdC) as a lead prodrug and conducted a detailed pharmacokinetic, metabolic, and pharmacodynamic evaluation. After intragastric Cbz-dFdC administration, the C_max of Cbz-dFdC and dFdC was 451.1 ± 106.7 and 1656.3 ± 431.5 ng/mL, respectively. The T_max of Cbz-dFdC and dFdC was 2 and 4 h, respectively. After intragastric administration of Cbz-dFdC, this compound was mainly distributed in the intestine due to low carboxylesterase-1 (CES1) activity. Cbz-dFdC is activated by CES1 in both humans and rats. The enzyme kinetic curves were well fitted by the Michaelis–Menten equation in rats’ blood, plasma, and tissue homogenates and S9 of the liver and kidney, as well as human liver S9 and CES1 recombinase. The pharmacodynamic results showed that the Cbz-dFdC have a good antitumor effect in the HepG2 cell and in tumor-bearing mice, respectively. In general, Cbz-dFdC has good pharmaceutical characteristics and is therefore a good candidate for a potential prodrug.

Mechanistic Multiscale Pharmacokinetic Model for the Anticancer Drug 2',2'-difluorodeoxycytidine (Gemcitabine) in Pancreatic Cancer

The aim of this work is to build a mechanistic multiscale pharmacokinetic model for the anticancer drug 2’,2’‐difluorodeoxycytidine (gemcitabine, dFdC), able to describe the concentrations of dFdC metabolites in the pancreatic tumor tissue in dependence of physiological and genetic patient characteristics, and, more in general, to explore the capabilities and limitations of this kind of modeling strategy. A mechanistic model characterizing dFdC metabolic pathway (metabolic network) was developed using in vitro literature data from two pancreatic cancer cell lines. The network was able to describe the time course of extracellular and intracellular dFdC metabolites concentrations. Moreover, a physiologically‐based pharmacokinetic model was developed to describe clinical dFdC profiles by using enzymatic and physiological information available in the literature. This model was then coupled with the metabolic network to describe the dFdC active metabolite profile in the pancreatic tumor tissue. Finally, global sensitivity analysis was performed to identify the parameters that mainly drive the interindividual variability for the area under the curve (AUC) of dFdC in plasma and of its active metabolite (dFdCTP) in tumor tissue. From this analysis, cytidine deaminase (CDA) concentration was identified as the main driver of plasma dFdC AUC interindividual variability, whereas CDA and deoxycytidine kinase concentration mainly explained the tumor dFdCTP AUC variability. However, the lack of in vitro and in vivo information needed to characterize key model parameters hampers the development of this kind of mechanistic approach. Further studies to better characterize pancreatic cell lines and patient enzymes polymorphisms are encouraged to refine and validate the current model.

Crystal structure and proposed mechanism of an enantioselective hydroalkoxylation enzyme from Penicillium herquei

Hydroalkoxylation is a useful and efficient reaction which generates C-O bond and produces cyclic ethers, the common structural elements of natural products. The dedicative enzyme which can catalyze enantioselective hydroalkoxylation named PhnH was recently identified in the herqueinone biosynthetic gene from Penicillium herquei. It catalyzes addition of a phenol to the terminal olefin on substrate to produce a dihydrobenzofuran. Here, the crystal structure of PhnH is reported and the putative substrate-binding pocket is illustrated. Through docking experiment, possible substrate-binding poses are displayed and the catalytic mechanism is therefore proposed. Our findings form the basis for further studies of enantioselective hydroalkoxylation enzymes.

Gemcitabine-based chemotherapy as a viable option for treatment of advanced breast cancer patients: a meta-analysis and literature review

This meta-analysis was designed to compare the efficacy and safety of gemcitabine-based regimens for the treatment advanced breast cancer (ABC). Altogether 15 studies involving 8195 ABC patients were retrieved for analysis. Compared with non-gemcitabine-based chemotherapies, patients receiving gemcitabine-based therapy exhibited better overall survival (OS), progression free survival (PFS), and objective response rate (ORR) (HR = 1.12, 95% CI 1.05 to 1.19; HR = 1.16, 95% CI 1.03 to 1.30; HR = 1.14, 95% CI 1.04 to 1.24). Grade 3/4 hematologic toxicity was significantly high but manageable in gemcitabine-based groups. Subgroup analysis revealed that patients with first-line gemcitabine-based chemotherapy had better OS (HR = 1.19, 95% CI 1.07 to 1.32), PFS (HR = 1.17, 95% CI 1.08 to 1.27), and ORR (RR = 1.16, 95% CI 1.02 to 1.32). In addition, additional gemcitabine chemotherapy also showed better OS (HR = 1.17, 95% CI 1.06 to 1.30), PFS (HR = 1.20, 95% CI 1.11 to 1.30) and ORR (RR = 1.23, 95% CI 1.06 to 1.42) than gemcitabine replacement therapy. Furthermore, patients receiving gemcitabine-taxanes-based regimens had better OS (HR = 1.17, 95% CI 1.06 to 1.28), PFS (HR = 1.12, 95% CI 1.04 to 1.20) and ORR (RR = 1.17, 95% CI 1.01 to 1.35) than patients with non-gemcitabine-taxanes-based chemotherapy. These findings indicate that gemcitabine combination regimens could serve as a promising regimen for ABC patients, though increased hematologic toxicity should be considered with caution.

Gemcitabine Integrated Nano-Prodrug Carrier System

Peptide nanomaterials have received a great deal of interest in drug-delivery applications due to their biodegradability, biocompatibility, suitability for large-scale synthesis, high drug-loading capacities, targeting ability, and ordered structural organization. The covalent conjugation of drugs to peptide backbones results in prolonged circulation time and improved stability of drugs. Therapeutic efficacy of gemcitabine, which is used for breast cancer treatment, is severely compromised due to its rapid plasma degradation. Its hydrophilic nature poses a challenge for both its efficient encapsulation into nanocarrier systems and its sustained release property. Here, we designed a new peptide prodrug molecule for the anticancer drug gemcitabine, which was covalently conjugated to the C-terminal of 9-fluorenylmethoxy carbonyl (Fmoc)-protected glycine. The prodrug was further integrated into peptide nanocarrier system through noncovalent interactions. A pair of oppositely charged amyloid-inspired peptides (Fmoc-AIPs) were exploited as components of the drug-carrier system and self-assembled into one-dimensional nanofibers at physiological conditions. The gemcitabine integrated nanoprodrug carrier system exhibited slow release and reduced the cellular viability of 4T1 breast cancer cell line in a time- and concentration-dependent manner.

Synthesis and biological evaluation of nitric oxide-releasing hybrids from gemcitabine and phenylsulfonyl furoxans as anti-tumor agents

Novel furoxan/gemcitabine hybrids displayed significant antitumor activities, in particular 10e, which could be independent of the nucleoside transporter, release high levels of NO, and induce cell apoptosis by regulating apoptotic related proteins in tumor cells in vitro.

The identification of novel 5'-amino gemcitabine analogs as potent RRM1 inhibitors

The ribonucleotide reductase (RNR) enzyme is a heteromer of RRM1 and RRM2 subunits. The active enzyme catalyzes de novo reduction of ribonucleotides to generate deoxyribonucleotides (dNTPs), which are required for DNA replication and DNA repair processes. Complexity in the generation of physiologically relevant, active RRM1/RRM2 heterodimers was perceived as limiting to the identification of selective RRM1 inhibitors by high-throughput screening of compound libraries and led us to seek alternative methods to identify lead series. In short, we found that gemcitabine, as its diphosphate metabolite, represents one of the few described active site inhibitors of RRM1. We herein describe the identification of novel 5'-amino gemcitabine analogs as potent RRM1 inhibitors through in-cell phenotypic screening.

Application of ProTide technology to gemcitabine: a successful approach to overcome the key cancer resistance mechanisms leads to a new agent (NUC-1031) in clinical development

Gemcitabine is a nucleoside analogue commonly used in cancer therapy but with limited efficacy due to a high susceptibility to cancer cell resistance. The addition of a phosphoramidate motif to the gemcitabine can protect it against many of the key cancer resistance mechanisms. We have synthesized a series of gemcitabine phosphoramidate prodrugs and screened for cytostatic activity in a range of different tumor cell lines. Among the synthesized compounds, one in particular (NUC-1031, 6f) was shown to be potent in vitro. Importantly, compared with gemcitabine, 6f activation was significantly less dependent on deoxycytidine kinase and on nucleoside transporters, and it was resistant to cytidine deaminase-mediated degradation. Moreover, 6f showed a significant reduction in tumor volumes in vivo in pancreatic cancer xenografts. The ProTide 6f is now in clinical development with encouraging efficacy signals in a Phase I/II study, which strongly supports the ProTide approach to generate promising new anticancer agents.

Effects of 5-fluorouracil and gemcitabine on a breast cancer cell line (MCF-7) via the JAK/STAT pathway

Aberrant activation of the JAK/STAT pathway may predispose to malignancy as a consequence of the deregulation of cell proliferation, differentiation or apoptosis such as in cancer of the blood, head and neck, and breast. In our study we aimed to investigate the effects of 5-fluorouracil (5-FU) and gemcitabine on a breast cancer cell line (MCF-7 cells) via the JAK/STAT pathway. Distribution of JAK1, JAK2, JAK3 and STAT2, STAT3, STAT4, STAT5 were evaluated on MCF-7 cells following gemcitabine and 5-FU treatment and in the absence of drug treatment by an indirect immunohistochemical method. It was observed that JAK1, JAK3, STAT5 and particularly STAT2 activation were more effective than the other JAK/STATs in breast cancer progression. Following treatment with 5-FU, JAK1 and STAT5 immunoreactivities were decreased in MCF-7 cells in comparison with both gemcitabine-treated and non-treated groups. These results suggest that the JAK/STAT pathway plays an important role in breast cancer pathogenesis and may be more affected after 5-FU treatment rather than gemcitabine. Drugs which block STAT5 may provide a novel therapeutic approach for the treatment of breast cancer.

The deaminated metabolite of gemcitabine, 2',2'-difluorodeoxyuridine, modulates the rate of gemcitabine transport and intracellular phosphorylation via deoxycytidine kinase

Gemcitabine (dFdC) is a chemotherapeutic nucleoside analog that undergoes uptake via equilibrative nucleoside transporters (hENT) followed by sequential phosphorylation to the active triphosphate moiety (dFdCTP). Its deaminated metabolite, 2',2'-difluorodeoxyuridine (dFdU), competes with the parent compound for cellular entry via hENTs, but over time dFdU increases the net intracellular accumulation of dFdC by a currently unknown mechanism. In this study, we investigated whether dFdU affects intracellular phosphorylation of gemcitabine by modulating the activity of deoxycytidine kinase (dCK). We report here that coincubation of dFdU with dFdC significantly increases intracellular levels of dFdCTP. dFdCTP was not identified as a substrate for hENTs, suggesting that dFdU affects the formation rather than elimination of the triphosphate. To further characterize the disposition of dFdC in the presence of dFdU, the net intracellular radioactivity of [5-(3)H]dFdC and corresponding metabolic profile were evaluated in HeLa cells transfected with dCK-targeting small interfering RNA. Intracellular radioactivity significantly decreased in cells with compromised intracellular phosphorylation, which was mainly due to a loss in dFdCTP. Although dFdU increased the net intracellular radioactivity of [5-(3)H]dFdC at 24 h in control cells, this increase was abolished in the absence of dCK activity, strongly suggesting that the interaction between dFdU and dFdC occurs via modulation of both transport and metabolism. In conclusion, we have demonstrated that the intracellular distribution of dFdC is dependent on both transport and metabolic processes, and that by affecting the rate at which dFdC enters the cell, the presence of dFdU may be altering the metabolic fate of the parent compound (dFdC).

Randomised phase II trial of gemcitabine plus vinorelbine vs gemcitabine plus cisplatin vs gemcitabine plus capecitabine in patients with pretreated metastatic breast cancer

BACKGROUND

An increasing proportion of patients are exposed to anthracyclines and/or taxanes in the adjuvant or neoadjuvant setting. Re-exposure in the metastatic stage is limited by drug resistance, thus evaluation of non-cross-resistant regimens is mandatory.

METHODS

Anthracycline-pretreated patients were randomly assigned to three gemcitabine-based regimens. Chemotherapy consisted of gemcitabine 1.000 mg m(-2) plus vinorelbin 25 mg m(-2) on days 1+8 (GemVin), or plus cisplatin 30 mg m(-2) on days 1+8 (GemCis), or plus capecitabine 650 mg m(-2) b.i.d. orally days 1-14 (GemCap), q3w. The primary end point was response rate.

RESULTS

A total of 141 patients were recruited on the trial. The overall response rates were 39.0% (GemVin), 47.7% (GemCis) and 34.7% (GemCap). Median progression-free survival was estimated with 5.7, 6.9 and 8.3 months, respectively. Corresponding median survival times were 17.5 (GemVin), 13.0 (GemCis) and 19.4 months (GemCap). Neutropenia ≥grade 3 occurred in 16.7% (Gem/Vin), 4.4% (GemCis) and 0% (Gem/Cap), whereas non-haematological toxicities were rarely severe except grade 3 hand-foot syndrome in 2.0% of the GemCap patients (per patient analysis).

CONCLUSIONS

This randomised phase II trial has revealed comparable results for three gemcitabine-based regimens regarding treatment efficacy and toxicity. Gemcitabine-based chemotherapy appears to be a worthwhile treatment option for pretreated patients with metastatic breast cancer.

Population pharmacokinetics of gemcitabine and its metabolite in patients with cancer: effect of oxaliplatin and infusion rate

What is already known about this subject. Gemcitabine is an anticancer drug which is metabolized to a number of metabolites, administered using different dosing regimens and increasingly used in combination with oxaliplatin. the impact of dosing strategies and combination therapy on the pharmacokinetics of gemcitabine and its main metabolite is not clearly understood. what this study adds. this study has characterized the pharmacokinetics of gemcitabine and its main metabolite in people with cancer, including the variability between patients and on different occasions. gemcitabine metabolite (but not gemcitabine) pharmacokinetics were significantly affected by co-administration with oxaliplatin and were dependent on the order of administration. the clinical implications of this observation remain to be established.

AIMS

To characterize the population pharmacokinetics of gemcitabine and its metabolite (dfdu) in patients with cancer and identify factors that are influential in gemcitabine dose regimen design.

METHODS

Gemcitabine and dfdu plasma concentration-time and clinical data from 94 patients with cancer and nonlinear mixed effect modelling were used to characterize gemcitabine and metabolite pharmacokinetic variability and identify influential covariates.

RESULTS

Gemcitabine and dFdU pharmacokinetics were described by a two-compartment model with first-order elimination. The population mean (and between-subject variability, CV%) for clearance and volume of distribution of the central compartment (V(C)) for gemcitabine were 2.7 l min(-1) (31%) and 15 l (39%), respectively, and 0.04 l min(-1) (35%) and 46 l (15%), respectively, for dFdU. Oxaliplatin co-administration significantly decreased dFdU V(C) by 35% when gemcitabine was administered first and by 46% when oxaliplatin was administered first compared with patients who received gemcitabine alone.

CONCLUSIONS

Co-administration of gemcitabine with oxaliplatin significantly affected the pharmacokinetics of dFdU. The clinical significance of this observation in the context of gemcitabine safety and efficacy is worthy of further investigation.

Gemcitabine plus vinorelbine versus vinorelbine monotherapy in patients with metastatic breast cancer previously treated with anthracyclines and taxanes: final results of the phase III Spanish Breast Cancer Research Group (GEICAM) trial

BACKGROUND

We aimed to compare the additional benefit of gemcitabine when combined with vinorelbine above that of standard vinorelbine treatment in patients with metastatic breast cancer.

METHODS

In this phase III, multicentre, open-label, randomised study, 252 women with locally recurrent and metastatic breast cancer who had been pretreated with anthracyclines and taxanes were randomly assigned single-agent vinorelbine (30 mg/m(2), days 1 and 8) or gemcitabine plus vinorelbine (1200/30 mg/m(2), days 1 and 8). Both study treatments were administered intravenously every 21 days until disease progression, unacceptable toxic effects, or stoppage at the request of investigator or patient. The primary endpoint was median progression-free survival. Secondary objectives included assessments of response rate, disease duration, overall survival, and characterisation of the toxicity profiles of both regimens. This study is registered with ClinicalTrials.gov, number NCT00128310.

FINDINGS

Between 2001 and 2005, 252 women were recruited and randomised for treatment. One of these patients was ineligible. Prognostic factors were well balanced between treatment groups (median number of metastatic sites in combination group 2 (range 0-5) and in vinorelbine group 2 (range 1-6); visceral disease in 76% and 75% of patients, respectively). Median progression-free survival was 6.0 months (95% CI 4.8-7.1) for patients given gemcitabine plus vinorelbine and 4.0 months (2.9-5.1) for those assigned vinorelbine; there was 1.9 months of difference (hazard ratio 0.66 [0.50-0.88]; p=0.0028). Overall survival was 15.9 months (12.6-19.1) for the gemcitabine plus vinorelbine group and 16.4 months (11.6-21.0) for the vinorelbine group; there was 0.5 months of difference (hazard ratio 1.04 [0.78-1.39]; p=0.8046). Objective response rates were 36% for patients assigned gemcitabine plus vinorelbine (n=45) and 26% for those assigned vinorelbine (n=33) (p=0.093). Grade 3 or 4 neutropenia was reported in 75 (61% [52-70]) of the participants assigned gemcitabine plus vinorelbine, compared with 55 (44% [35-53]) of those assigned vinorelbine alone (p=0.0074). Febrile neutropenia occurred in 13 (11%) of those assigned gemcitabine plus vinorelbine, and in seven (6%) of those assigned vinorelbine alone (p=0.15). Incidences of grade 3 or 4 non-haematological toxic effects were similar between the two treatment groups.

INTERPRETATION

Patients with metastatic breast cancer assigned gemcitabine and vinorelbine had better progression-free survival compared with those assigned vinorelbine alone. However, this finding did not translate into a difference in overall survival. Although toxicity was manageable, patients in the combined group had more haematological toxic effects. These factors should be taken into account when deciding which chemotherapy patients should receive.

Gene expression profiling of breast cancer cells in response to gemcitabine: NF-κB pathway activation as a potential mechanism of resistance

Gemcitabine is a nucleoside analog with clinical relevance in the treatment of several solid tumors, including breast carcinoma. In spite of its cytotoxic effect, clinical efficacy is impaired by the development of resistance. We performed gene expression analysis to shed light into the molecular mechanism of action of this drug in two breast cancer cell lines. Activation of genes related with cell cycle, cell growth and apoptosis (BNIP3L, CCNG2, DDIT4, TGFB2, TP53BP1, TP53INP1, and VEGF) was the main finding in the p53-wild type cell line MCF7, while the p53-non-functional cell line MDA-MB-231 was characterized by the regulation of NF-kappaB target genes (BIRC3, CXCL1/GRO1, IRAK2, TNF, TNFAIP and TRAF1). Genes consistently induced (ATF3, CCNG2, CDKN1A, EGR1, INSIG1, and MAF) or repressed (CCND1 and VGF) in both cell lines, were also found after gemcitabine treatment. In addition, MDA-MB-231 cells showed a higher basal and induced NF-kappaB transcriptional activity after treatment with gemcitabine. In comparison with gemcitabine, gene expression after 5-fluorouracil treatment showed essentially different profiles in both cell lines. This, in spite of using equitoxic concentrations producing similar effects on cell cycle. NF-kappaB transcriptional activity in MDA-MB-231 cells was dependent on IkappaB-alpha phosphorylation, as shown by functional experiments using the specific inhibitor BAY11-7082. Moreover, immunohistochemical analysis of clinical samples of breast carcinoma further validated the induction of NF-kappaB expression and IkappaB down-regulation upon neoadjuvant gemcitabine treatment. Thus, gene expression patterns, in vitro functional studies and analysis of tissue samples are in agreement with a role for NF-kappaB pathway in gemcitabine response. Together with the reported role for NF-kappaB in the induction of resistance to chemotherapy, our data gives support to clinical strategies combining gemcitabine with NF-kappaB inhibitors in breast cancer.

High efficacy of combined rituximab and gemcitabine on Epstein–Barr virus-associated human B-cell lymphoma obtained after Hodgkin's xenograft in immunodeficient mice

The objectives were to characterize an Epstein-Barr virus-associated human B-cell lymphoma obtained from Hodgkin's xenograft, and to evaluate the in-vivo combination of rituximab and/or gemcitabine. A lymph node biopsy sample from a patient with Hodgkin's disease was xenografted into Rag gamma(c)(-/-) mice. Immunohistochemical, cytogenetic and genetic analyses were performed on both the human biopsy and xenografted tumor from severe combined immunodeficient mice. Tumor-bearing mice were then treated with rituximab and/or gemcitabine. Histologic features of the patient's biopsy concluded on classical CD15/CD30-positive Hodgkin's disease without expression of Epstein-Barr virus proteins. In contrast, morphologic and immunophenotypic examination of the xenograft showed diffuse proliferation of large B cells with high Epstein-Barr virus protein expression. Comparative genomic hybridization showed a normal pattern in the first case and a gain of chromosomal 12 in the xenografted tumor. Finally, polymerase chain reaction detected an immunoglobulin heavy chain rearrangement in the xenografted tumor. Altogether, these results indicate that the xenograft grew from the patient's Epstein-Barr virus-infected B-lymphoid cells and could be assimilated to posttransplant lymphoproliferative disease. In-vivo treatments of xenografted tumors showed significant tumor growth inhibition induced either by rituximab or gemcitabine alone and an impressive efficacy of combined treatment. This result therefore indicates that combined rituximab and gemcitabine could be an alternative approach in patients with posttransplant lymphoproliferative disease.

Gemcitabine: monochemotherapy of breast cancer

BACKGROUND

Gemcitabine is a nucleoside analogue with proven activity in advanced and metastatic breast cancer. Its action is associated with a favourable toxicity profile which is mainly hematological. Its unique mechanism of action along with not overlapping toxicity is particularly useful both in combination treatment with other active drugs and a sequential therapy in the palliative setting.

DESIGN

Phase II studies of gemcitabine performed over the last decade were reviewed.

RESULTS AND CONCLUSIONS

Despite some conflicting results in some trials, gemcitabine confirmed to be a useful drug to treat this condition.