Ultra-sensitive LC-MS/MS method for the quantification of gemcitabine and its metabolite 2',2'-difluorodeoxyuridine in human plasma for a microdose clinical trial

An innovative and universal dual-signal ratiometric spectro-electrochemical imprinted sensor design for sandwich type detection of anticancer-drug, gemcitabine, in serum samples; cross validation via computational modeling

An innovative and universal imprinted sensor design for sandwich type detection of gemcitabine (GMT) in human serum samples is described. GMT is widely used in the treatment of different tumors, such as lung, ovarian, pancreatic, and breast cancer. The serum albumin-drug interaction was translated to design a multifunctional, ratiometric and dual mode silver nanoparticle based probe (BSA-Ag nanoprobe), as a read out system. Subsequently, polypyrrol imprinted drug receptor sites was engineered to selectively capture the GMT on the transducer surface. The GMT was sandwiched between imprinted receptor surface and BSA-Ag nanoprobe to generate the spectro-electrochemical signals. The formation of nanoprobe was confirmed through various characterization techniques, including X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, micro-Raman spectroscopy, Dynamic light scattering (DLS), and UV-Visible (UV-Vis) analysis, while each step of sensor fabrication was characterized via field emission scanning electron microscope (FE-SEM), Static water Contact angle measurements, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). Different variable parameters were optimized to improve the analytical performance of the sensor design. Under optimal conditions, spectro-electrochemical sensor permitted linear ranges between 1 and 200 μmol L-1 and 0.5-200 μmol L-1, with limits of detection (LOD) of 0.4 μmol L-1 and 0.15 μmol L-1 respectively. Furthermore, the designed sensor successfully differentiated the serum samples of lung cancer patients and healthy volunteers. The obtained results were validated with standard Liquid chromatography-mass spectrometry (LC/MS) analysis of the patients and healthy volunteer's serum samples. Lastly, density functional theory (DFT) and molecular docking calculations revealed the enhanced GMT binding capability of molecularly imprinted polypyrrole and molecular level interaction between the GMT and BSA, to validate the sandwich sensor design.

The Effect of PEGylation on Drugs' Pharmacokinetic Parameters; from Absorption to Excretion

Until the drugs enter humans life, they may face problems in transportation, drug delivery, and metabolism. These problems can cause reducing drug's therapeutic effect and even increase its side effects. Together, these cases can reduce the patient's compliance with the treatment and complicate the treatment process. Much work has been done to solve or at least reduce these problems. For example, using different forms of a single drug molecule (like Citalopram and Escitalopram); slight changes in the drug's molecule like Meperidine and α-Prodine, and using carriers (like Tigerase®). PEGylation is a recently presented method that can use for many targets. Poly Ethylene Glycol or PEG is a polymer that can attach to drugs by using different methods and resulting sustained release, controlled metabolism, targeted delivery, and other cases. Although they will not necessarily lead to an increase in the effect of the drug, they will lead to the improvement of the treatment process in certain ways. In this article, the team of authors has tried to collect and carefully review the best cases based on the PEGylation of drugs that can help the readers of this article.

Development and validation of simultaneous quantification method for gemcitabine and betulinic acid: augmenting industrial application

Combinatorial treatment utilizing a nucleoside analogue gemcitabine (GEM), with a characteristic pentacyclic triterpenoid betulinic acid (BET), has exhibited empowering adequacy in the therapy of cancer. It lessens the advancement of collagen and upgrades the saturation of tumour medicines. With the advancement in nanotechnology, the co-loaded formulation urges for a validated method of estimation. The purposed work entails a robust, simple, and economical analytical method for the simultaneous estimation of GEM and BET through RP-HPLC. Orthophosphoric acid (0.1%)-acetonitrile was considered as the mobile phase for the detection of GEM and BET at 248 nm and 210 nm with retention times of 5 min and 13 min, respectively. The method was further validated as per the regulatory guidelines with all the parameters found within the limit. The developed method with adequate resolution and quantification was found to be linear, accurate, precise, robust, and stable with an intra- and inter-day variability of less than 2%. The method was found specific for GEM and BET with no matrix interference of drug-spiked FBS samples. To demonstrate the applicability of the developed method, a nano-formulation containing GEM and BET was prepared and assessed for various parameters including encapsulation efficiency, loading efficiency, drug release, and drug stability. The method developed can be a possible tool for the simultaneous quantification of GEM-BET in analytical and biological samples.

Determination of Bendamustine, Gemcitabine and Vinorelbine (BEGEV) regimen in spiked human plasma using multivariate model update chemometric methods

Combination of bendamustine (BEN), gemcitabine (GEM), and vinorelbine (VIB), (BEGEV) regimen, has been proved to be a tolerable, safe and effective regimen in relapsed/refractory classical hodgkin lymphoma (R/R cHL). Two chemometric models named principal component regression (PCR) and partial least squares (PLS) were established for determination and quantification of BEN, GEM and VIB simultaneously in the ranges of 5-25 µg/mL for each of BEN and VIB, while in the range of 10 -30 µg/mL for GEM in pure and spiked plasma using their UV absorbance. The updated methods have been proven their ability to predict the concentrations of the studied drugs and validated according to FDA guidelines showing good results. There was no significant difference between the developed methods and the reported LC-MS/MS method upon statistical comparison was applied. Furthermore, the updated chemometric methods have advantages of being sensitive, accurate and cost effective for estimation of BEN, GEM and VIB and monitoring their concentration.

A naïve pooled data approach for extrapolation of Phase 0 microdose trials to therapeutic dosing regimens

Microdosing is a strategy to obtain knowledge of human pharmacokinetics prior to Phase I clinical trials. The most frequently used method to extrapolate microdose (≤100 μg) pharmacokinetics to therapeutic doses is based on linear extrapolation from a noncompartmental analysis (NCA) with a two-fold acceptance criterion between pharmacokinetic metrics of the extrapolated microdose and the therapeutic dose. The major disadvantage of NCA is the assumption of linear extrapolation of NCA metrics. In this study, we used a naïve pooled data (NPD) modeling approach to extrapolate microdose pharmacokinetics to therapeutic pharmacokinetics. Gemcitabine and anastrozole were used as examples of intravenous and oral drugs, respectively. Data from microdose studies were used to build a parent-metabolite model for gemcitabine and its metabolite 2',2'-difluorodeoxyuridine (dFdU) and a model for anastrozole. The pharmacokinetic microdose models were extrapolated to therapeutic doses. Extrapolation of the microdose showed differences in pharmacokinetic shape for gemcitabine and dFdU between the simulated and observed therapeutic concentrations, whereas the observed therapeutic concentrations for anastrozole were captured by the extrapolation. This study demonstrated the possible use and feasibility of an NPD modeling approach for the evaluation and application of microdose studies in early drug development. Last, physiologically-based pharmacokinetic modeling might be an alternative for microdose extrapolation of drugs with complex pharmacokinetics such as gemcitabine.

Interactions of Some Chemotherapeutic Agents as Epirubicin, Gemcitabine and Paclitaxel in Multicomponent Systems Based on Orange Essential Oil

In order to anticipate the effect induced by a natural product on the chemical activity of medicines simultaneously administered, spontaneous interactions of certain cancer treatment drugs such as, epirubicin (EPR), gemcitabine (GCT), and paclitaxel (PTX) with limonene (LIM)—a natural compound extracted from orange peel and known as an anticancer agent—were investigated. To estimate the stability of the drugs over time, a current density of 50 mA cm⁻² was applied as an external stimulus between two platinum electrodes immersed in hydrochloric acid solution containing ethyl alcohol/water in the volume ratio of 2/3, in the absence and presence of orange essential oil (limonene concentration of 95%). The concentration variation of chemotherapeutic agents over time was evaluated by UV-Vis spectrophotometry. Kinetic studies have shown a delay in the decomposition reaction of epirubicin and gemcitabine and a paclitaxel activity stimulation. Thus, in the presence of limonene, the epirubicin half-life increased from 46.2 min to 63 min, and from 6.2 min to 8.6 min in gemcitabine case, while for paclitaxel a decrease of half-life from 35.9 min to 25.8 min was determined. Therefore, certain drug-limonene interactions took place, leading to the emergence of molecular micro-assemblies impacting decomposition reaction of chemotherapeutics. To predict drug–limonene interactions, the Autodock 4.2.6 system was employed. Thus, two hydrophobic interactions and five π-alkyl interactions were established between EPR-LIM, the GCT-LIM connection involves four π-alkyl interactions, and the PTX-LIM bridges take place through three hydrophobic interactions and the one π-alkyl. Finally, the decomposition reaction mechanism of drugs was proposed.

Combining Isotopic Tracer Techniques to Increase Efficiency of Clinical Pharmacokinetic Trials in Oncology

With increasing numbers of drugs tested in oncology for smaller patient populations, fewer patients are available to answer important clinical pharmacological questions in the timeframe of clinical drug development. The quality and efficiency of trials to assess the pharmacokinetics of new drugs can be improved by making better use of available resources. One approach to do this is by making more effective use of isotopic tracer techniques. With increasing sensitivity of liquid chromatography-tandem mass spectrometry analyzing equipment over the years, it has now become possible to generate much more rich, high-quality pharmacokinetic data than before. In particular we want to make a plea here for a hybrid trial approach, where both radiolabeled drug and stable isotopically labeled drug are administered to patients to assess both the absolute bioavailability and absorption, distribution, metabolism and excretion in a single clinical trial experiment.

Phase 0/microdosing approaches: time for mainstream application in drug development?

Phase 0 approaches - which include microdosing - evaluate subtherapeutic exposures of new drugs in first-in-human studies known as exploratory clinical trials. Recent progress extends phase 0 benefits beyond assessment of pharmacokinetics to include understanding of mechanism of action and pharmacodynamics. Phase 0 approaches have the potential to improve preclinical candidate selection and enable safer, cheaper, quicker and more informed developmental decisions. Here, we discuss phase 0 methods and applications, highlight their advantages over traditional strategies and address concerns related to extrapolation and developmental timelines. Although challenges remain, we propose that phase 0 approaches be at least considered for application in most drug development scenarios.

ZIP4 Increases Expression of Transcription Factor ZEB1 to Promote Integrin α3β1 Signaling and Inhibit Expression of the Gemcitabine Transporter ENT1 in Pancreatic Cancer Cells

BACKGROUND & AIMS

Pancreatic tumors undergo rapid growth and progression, become resistant to chemotherapy, and recur after surgery. We studied the functions of the solute carrier family 39 member 4 (SLC39A4, also called ZIP4), which regulates concentrations of intracellular zinc and is increased in pancreatic cancer cells, in cell lines and mice.

METHODS

We obtained 93 pancreatic cancer specimens (tumor and adjacent nontumor tissues) from patients who underwent surgery and gemcitabine chemotherapy and analyzed them by immunohistochemistry. ZIP4 and/or ITGA3 or ITGB1 were overexpressed or knocked down with short hairpin RNAs in AsPC-1 and MIA PaCa-2 pancreatic cancer cells lines, and in pancreatic cells from KPC and KPC-ZEB1-knockout mice, and pancreatic spheroids were established; cells and spheroids were analyzed by immunoblots, reverse transcription polymerase chain reaction, and liquid chromatography tandem mass spectrometry. We studied transcriptional regulation of ZEB1, ITGA3, ITGB1, JNK, and ENT1 by ZIP4 using chromatin precipitation and luciferase reporter assays. Nude mice were given injections of genetically manipulated AsPC-1 and MIA PaCa-2 cells, and growth of xenograft tumors and metastases was measured.

RESULTS

In pancreatic cancer specimens from patients, increased levels of ZIP4 were associated with shorter survival times. MIA PaCa-2 cells that overexpressed ZIP4 had increased resistance to gemcitabine, 5-fluorouracil, and cisplatin, whereas AsPC-1 cells with ZIP4 knockdown had increased sensitivity to these drugs. In mice, xenograft tumors grown from AsPC-1 cells with ZIP4 knockdown were smaller and more sensitive to gemcitabine. ZIP4 overexpression significantly reduced accumulation of gemcitabine in pancreatic cancer cells, increased growth of xenograft tumors in mice, and increased expression of the integrin subunits ITGA3 and ITGB1; expression levels of ITGA3 and ITGB1 were reduced in cells with ZIP4 knockdown. Pancreatic cancer cells with ITGA3 or ITGB1 knockdown had reduced proliferation and formed smaller tumors in mice, despite overexpression of ZIP4; spheroids established from these cells had increased sensitivity to gemcitabine. We found ZIP4 to activate STAT3 to induce expression of ZEB1, which induced expression of ITGA3 and ITGB1 in KPC cells. Increased ITGA3 and ITGB1 expression and subsequent integrin α3β1 signaling, via c-Jun-N-terminal kinase (JNK), inhibited expression of the gemcitabine transporter ENT1, which reduced gemcitabine uptake by pancreatic cancer cells. ZEB1-knockdown cells had increased sensitivity to gemcitabine.

CONCLUSIONS

In studies of pancreatic cancer cell lines and mice, we found that ZIP4 increases expression of the transcription factor ZEB1, which activates expression of ITGA3 and ITGB1. The subsequent increase in integrin α3β1 signaling, via JNK, inhibits expression of the gemcitabine transporter ENT1, so that cells take up smaller amounts of the drug. Activation of this pathway might help mediate resistance of pancreatic tumors to chemotherapeutic agents.

Pilot Study to Predict Pharmacokinetics of a Therapeutic Gemcitabine Dose From a Microdose

Microdose studies are exploratory trials to determine early drug pharmacokinetics in humans. In this trial we examined whether the pharmacokinetics of gemcitabine at a therapeutic dose could be predicted from the pharmacokinetics of a microdose. In this prospective, open-label microdosing study, a gemcitabine microdose (100 µg) was given intravenously to participants on day 1, followed by a therapeutic dose (1250 mg/m² ) on day 2. Gemcitabine and its metabolite 2',2'-difluorodeoxyuracil (dFdU) were quantified in plasma and intracellularly by using liquid chromatography-mass spectrometry). Noncompartmental pharmacokinetic analysis was performed. Ten patients participated in this study. The mean area under the plasma concentration-time curve (AUC_0-8 ) of gemcitabine after microdosing was 0.00074 h·mg/L and after therapeutic dosing was 16 h·mg/L. The mean AUC_0-8 of dFdU following the microdose and therapeutic dose were 0.022 h·mg/L and 169 h·mg/L, respectively. Exposure to gemcitabine after the therapeutic dose was within 2-fold of the exposure following a microdose, when linearly extrapolated to 1250 mg/m² . However, the shape of the concentration-time curve was different, as reflected by poor scalability in volume of distribution (939 L versus 222 L). Furthermore, intracellularly phosphorylated gemcitabine and phosphorylated dFdU levels could not be predicted from the microdose. The AUC_0-8 of gemcitabine at therapeutic dose was accurately predicted by the pharmacokinetics of a microdose, when linearly extrapolated to 1250 mg/m² . Volume of distribution, elimination rate constant, and intracellular pharmacokinetics of the therapeutic dose could not be predicted from the microdose, which demonstrates limitations of the microdose approach in this case.

Utilization of data below the analytical limit of quantitation in pharmacokinetic analysis and modeling: promoting interdisciplinary debate

Traditionally, bioanalytical laboratories do not report actual concentrations for samples with results below the LOQ (BLQ) in pharmacokinetic studies. BLQ values are outside the method calibration range established during validation and no data are available to support the reliability of these values. However, ignoring BLQ data can contribute to bias and imprecision in model-based pharmacokinetic analyses. From this perspective, routine use of BLQ data would be advantageous. We would like to initiate an interdisciplinary debate on this important topic by summarizing the current concepts and use of BLQ data by regulators, pharmacometricians and bioanalysts. Through introducing the limit of detection and evaluating its variability, BLQ data could be released and utilized appropriately for pharmacokinetic research.