Population pharmacokinetics of cyclosporine in clinical renal transplant patients

A model based on machine learning for the prediction of cyclosporin A trough concentration in Chinese allo-HSCT patients

BACKGROUND

Cyclosporin A is a calcineurin inhibitor which has a narrow therapeutic window and high interindividual variability. Various population pharmacokinetic models have been reported; however, professional software and technical personnel were needed and the variables of the models were limited. Therefore, the aim of this study was to establish a model based on machine learning to predict CsA trough concentrations in Chinese allo-HSCT patients.

METHODS

A total of 7874 cases of CsA therapeutic drug monitoring data from 2069 allo-HSCT patients were retrospectively included. Sequential forward selection was used to select variable subsets, and eight different algorithms were applied to establish the prediction model.

RESULTS

XGBoost exhibited the highest prediction ability. Except for the variables that were identified by previous studies, some rarely reported variables were found, such as norethindrone, WBC, PAB, and hCRP. The prediction accuracy within ±30% of the actual trough concentration was above 0.80, and the predictive ability of the models was demonstrated to be effective in external validation.

CONCLUSION

In this study, models based on machine learning technology were established to predict CsA levels 3-4 days in advance during the early inpatient phase after HSCT. A new perspective for CsA clinical application is provided.

Monitoring of Ex Vivo Cyclosporin a Activity in Healthy Volunteers Using T Cell Function Assays in Relation to Whole Blood and Cellular Pharmacokinetics

Therapeutic drug monitoring (TDM) of calcineurin inhibitors (i.e., tacrolimus and cyclosporin A) is standard of care after solid organ transplantation. Although the incidence of acute rejection has strongly decreased, there are still many patients who experience severe side effects or rejection after long-term treatment. In this healthy volunteer study we therefore aimed to identify biomarkers to move from a pharmacokinetic-based towards a pharmacodynamic-based monitoring approach for calcineurin inhibitor treatment. Healthy volunteers received a single dose of cyclosporine A (CsA) or placebo, after which whole blood samples were stimulated to measure ex vivo T cell functionality, including proliferation, cytokine production, and activation marker expression. The highest whole blood concentration of CsA was found at 2 h post-dose, which resulted in a strong inhibition of interferon gamma (IFNy) and interleukin-2 (IL-2) production and expression of CD154 and CD71 on T cells. Moreover, the in vitro effect of CsA was studied by incubation of pre-dose whole blood samples with a concentration range of CsA. The average in vitro and ex vivo CsA activity overlapped, making the in vitro dose–effect relationship an interesting method for prediction of post-dose drug effect. The clinical relevance of the results is to be explored in transplantation patients on calcineurin inhibitor treatment.

Population Pharmacokinetics of Cyclosporine in Chinese Pediatric Patients With Acquired Aplastic Anemia

Cyclosporine (CsA) is a component of the first-line treatment for acquired aplastic anemia (acquired AA) in pediatric patients. This study aimed to develop a population pharmacokinetic (PK) model of CsA in Chinese pediatric patients with acquired AA to inform individual dosage regimens. A total of 681 CsA whole blood concentrations and laboratory data of 157 pediatric patients with acquired AA were retrospectively collected from two hospitals in Shanghai. A nonlinear mixed-effect model approach was used to build the population PK model. Potential covariate effects of age, body weight, and biochemical measurements (renal and liver functions) on CsA PK disposition were evaluated. Model fit was assessed using the basic goodness of fit and a visual predictive check. The CsA concentration data were accurately described using a two-compartment disposition model with first-order absorption and elimination. Body weight value was implemented as a fixed allometric function on all clearance and volume of distribution parameters. Total bilirubin level was identified as a significant covariate on apparent clearance (CL/F), with a 1.07% reduction per 1 nmol/L rise in total bilirubin level. The final estimates for CL/F and central volume (Vc/F) were 29.1 L/h and 325 L, respectively, for a typical 28 kg child. Other covariates (e.g., gender, age, albumin, hemoglobin, hematocrit, serum creatinine, and concomitant medication) did not significantly affect the PK properties of CsA. This population PK model, along with a maximum a posteriori Bayesian approach, could estimate individual PK parameters in pediatric patients with acquired AA to conduct individual CsA therapy.

Factors Affecting Time-Varying Clearance of Cyclosporine in Adult Renal Transplant Recipients: A Population Pharmacokinetic Perspective

AIM

The pharmacokinetic (PK) properties of cyclosporine (CsA) in renal transplant recipients are patient- and time-dependent. Knowledge of this time-related variability is necessary to maintain or achieve CsA target exposure. Here, we aimed to identify factors explaining variabilities in CsA PK properties and characterize time-varying clearance (CL/F) by performing a comprehensive analysis of CsA PK factors using population PK (popPK) modeling of long-term follow-up data from our institution.

METHODS

In total, 3674 whole-blood CsA concentrations from 183 patients who underwent initial renal transplantation were analyzed using nonlinear mixed-effects modeling. The effects of potential covariates were selected according to a previous study and well-accepted theoretical mechanisms. Model-informed individualized therapeutic regimens were also evaluated.

RESULTS

A two-compartment model adequately described the data and the estimated mean CsA CL/F was 32.6 L h^-1 (relative standard error: 5%). Allometrically scaled body size, hematocrit (HCT) level, CGC haplotype carrier status, and postoperative time may contribute to CsA PK variability. The CsA bioavailability in patients receiving a prednisolone dose (PD) of 80 mg was 20.6% lower than that in patients receiving 20 mg. A significant decrease (52.6%) in CL/F was observed as the HCT increased from 10.5% to 60.5%. The CL/F of the non-CGC haplotype carrier was 14.4% lower than that of the CGC haplotype carrier at 3 months post operation.

CONCLUSIONS

By monitoring body size, HCT, PD, and CGC haplotype, changes in CsA CL/F over time could be predicted. Such information could be used to optimize CsA therapy. CsA dose adjustments should be considered in different postoperative periods.

Incorporating nonlinear kinetics to improve predictive performance of population pharmacokinetic models for ciclosporin in adult renal transplant recipients: A comparison of modelling strategies

BACKGROUND

Ciclosporin has been shown to follow nonlinear pharmacokinetics (PK) in renal transplant recipients who received ciclosporin (Neoral^Ⓡ, Novartis)-based triple immunosuppressive therapy. Some of these nonlinear properties have not been fully considered in population PK (popPK) analysis. Therefore, the aim of this study was to determine the potential influence of nonlinearity and the functional forms of covariates on model predictability as well as to analyse multiple nonlinear factors in the in vivo process.

METHODS

A total of 2969 ciclosporin whole-blood measurements, including 1328 pre-dose and 1641 2-h post-dose concentrations, were collected from 173 patients who underwent their first renal transplantation. Four popPK models based on different modelling strategies were developed to investigate the discrepancy between empirical and theory-based, linear and nonlinear compartmental kinetic models and empirical formulae on model predictability. Prediction and simulation-based diagnostics (prediction-corrected visual predictive checks) were performed to determine the stability and predictive performance of these four models.

RESULTS

Model predictability improved when nonlinearity was considered. The theory-based nonlinear model which incorporated nonlinear property based on known theoretical relationships performed better than the other two compartmental models. The nonlinear Michaelis-Menten model showed a remarkable improvement in predictive performance compared to the other three compartmental models. The saturated binding of ciclosporin to erythrocytes, auto-inhibition induced by the inhibitory effects of ciclosporin on cytochrome P450 3A4/P-glycoprotein may have contributed to the nonlinearity. Ciclosporin-prednisolone drug interaction should be given serious consideration in clinical settings.

CONCLUSIONS

Incorporation of nonlinear properties is likely to be a promising approach for improving ciclosporin model predictability. Theory-based modelling is helpful to improve model predictability. However, ciclosporin nonlinear kinetics resources need further investigation.

Population Pharmacokinetic Modeling of Cyclosporine Among Malaysian Renal Transplant Patients: An Evaluation of Methods to Handle Missing Doses in Conventional Drug-Monitoring Data

Cyclosporine is a primary drug in transplant immunosuppression regimens. It has a narrow therapeutic index and variable pharmacokinetic behavior. This study aimed to develop a population pharmacokinetic model of cyclosporine in Malaysian renal transplant recipients as well as to evaluate the performances of different methodsfor handling missing doses. A total of 2804 concentrationts predose and 2 hours after doses were collected retrospectively from 113 renal transplant patients on cyclosporine in Penang General Hospital. Model structure and pharmacokinetic parameters were estimated using nonlinear mixed-effects modeling software. Missing doses were handled using different methods to evaluate their performance. Covariate analysis was performed using stepwise forward addition (P < .05) followed by backward elimination (P < .001). Prediction-corrected visual predictive check and sampling-importance resampling methods were used to validate the final model. A 1-compartment model with first-order absorption and elimination best fitted the data. All methods to handle missing doses performed well with the missing dose method being superior to other methods and thus was applied in the final model. Cyclosporine clearance (CL/F) was estimated as 15.1 L/h, and volume of distribution (V/F) was 108 L. Postoperative time, sex, and calcium channel blockers were identified as significant covariates on CL/F, whereas sex and cholesterol level were identified as significant covariates on V/F. This is the first population pharmacokinetic model developed in Malaysian renal transplant patients using a large sample with an evaluation of different methods to handle missing doses in less informative conventional therapeutic drug-monitoring data.

Multicenter-Based Population Pharmacokinetic Analysis of Ciclosporin in Hematopoietic Stem Cell Transplantation Patients

PURPOSE

To explore the contribution of physiological characteristics to variability in ciclosporin pharmacokinetics in hematopoietic stem cell transplantation patients.

METHODS

Clinical data from 563 patients were collected from centers in three regions. Ciclosporin concentrations were measured using immunoassays. The patients' demographics, hematological and biological indicators, coadministered drugs, region, and disease diagnosis were recorded from medical records. Data analysis was performed using NONMEM based on a one-compartment model to describe the pharmacokinetics of ciclosporin. The reliability and stability of the final model were evaluated using bootstrap resampling, goodness-of-fit plots, and prediction-corrected visual predictive checks.

RESULTS

The population estimate of the clearance (CL) was 30.4 L/h, the volume of distribution (V) was 874.0 L and the bioavailability (F) was 81.1%. The between-subject variability in these parameters was 26.3, 68.0, and 110.8%, respectively. Coadministration of fluconazole, itraconazole, or voriconazole decreased CL by 17.6%, 28.4%, and 29.2%, respectively. Females' CL increased by approximately 12.0%. In addition, CL and V decreased with hematocrit, total protein, and uric acid increase, and CL also decreased with age and aspartate aminotransferase increase. However, CL increased with creatinine clearance increase.

CONCLUSIONS

A multicenter-based population pharmacokinetic model of ciclosporin was established. The pharmacokinetics of ciclosporin exhibited discrepancies among different regions.

Population pharmacokinetics of cyclosporine in Chinese children receiving hematopoietic stem cell transplantation

Cyclosporine (CsA) is characterized by a narrow therapeutic window and high interindividual pharmacokinetic variability, particularly in juvenile patients. The aims of this study were to build a population pharmacokinetic model of CsA in Chinese children with hematopathy who received allogeneic hematopoietic stem cell transplantation (allo-HSCT) and to identify covariates affecting CsA pharmacokinetics. A total of 86 Chinese children aged 8.4 ± 3.8 years (range 1.1–16.8 years) who received allo-HSCT were enrolled. Whole blood samples were collected before allo-HSCT. Genotyping was performed using an Agena MassARRAY system. A total of 1010 trough plasma concentration values of CsA and clinical data were collected. The population pharmacokinetic model of CsA was constructed using nonlinear mixed-effects modeling (NONMEM) software. The stability and performance of the final model were validated using bootstrapping and normalized prediction distribution errors. We showed that a one-compartment model with first-order elimination adequately described the pharmacokinetics of CsA. The typical values for clearance (CL) and volume of distribution (V) were 42.3 L/h and 3100 L, respectively. Body weight, postoperative days, CYP3A4*1 G genotype, estimated glomerular filtration rate and coadministration of triazole antifungal drugs were identified as significant covariates for CL. Weight and postoperative days were significant covariates for the V of CsA. Our model can be adopted to optimize the CsA dosing regimen for Chinese children with hematopathy receiving allo-HSCT.

Characterizing the pharmacokinetics and pharmacodynamics of immunosuppressant medicines and patient outcomes in elderly renal transplant patients

This review examines what is currently known about the pharmacokinetics and pharmacodynamics of commonly prescribed immunosuppressant medicines, tacrolimus, cyclosporine, mycophenolate and prednisolone, in elderly renal transplant recipients, and reported patient outcomes in this cohort. Renal transplantation is increasing rapidly in the elderly, however, currently, long-term patient outcomes are relatively poor compared to younger adults. Some studies have suggested that elderly recipients may have higher dose-adjusted exposure and/or lower clearance of the calcineurin inhibitors tacrolimus and cyclosporine; with one study reporting up to 50% reduction in tacrolimus exposure in the elderly. Elderly transplant recipients do not appear to have higher dosage-adjusted exposure to mycophenolic acid (MPA). The effects of ageing on the pharmacokinetics of prednisolone are unknown. Only one study has examined how aging effects drug target enzymes, reporting no difference in baseline inosine 5'-monophosphate dehydrogenase (IMPDH) activity and MPA-induced IMPDH activity in elderly compared to younger adult renal transplant recipients. In elderly transplant recipients, immunosenescence likely lowers the risk of acute rejection, but increases the risk of drug-related adverse effects. Currently, the three main causes of death in elderly renal transplant recipients are cardiovascular disease, infection and malignancy. One study has showed that renal transplant recipients aged over 65 years are seven times more likely to die with a functioning graft compared with young adults (aged 18-29 years). This suggests that an optimal balance between immunosuppressant medicine efficacy and toxicity is not achieved in elderly recipients, and further studies are needed to foster long-term graft and patient survival. Lower maintenance immunosuppressant targets in elderly recipients may decrease patient susceptibility to drug side effects, however, further studies are required and appropriate targets need to be established.

Pharmacokinetics of Toxin-Derived Peptide Drugs

Toxins and venoms produced by different organisms contain peptides that have evolved to have highly selective and potent pharmacological effects on specific targets for protection and predation. Several toxin-derived peptides have become drugs and are used for the management of diabetes, hypertension, chronic pain, and other medical conditions. Despite the similarity in their composition (amino acids as the building blocks), toxin-derived peptide drugs have very profound differences in their structure and conformation, in their physicochemical properties (that affect solubility, stability, etc.), and subsequently in their pharmacokinetics (the processes of absorption, distribution, metabolism, and elimination following their administration to patients). This review summarizes and critically analyzes the pharmacokinetic properties of toxin-derived peptide drugs: (1) the relationship between the chemical structure, physicochemical properties, and the pharmacokinetics of the specific drugs, (2) the major pharmacokinetic properties and parameters of these drugs, and (3) the major pharmacokinetic variability factors of the individual drugs. The structural properties of toxin-derived peptides affect their pharmacokinetics and pose some limitations on their clinical use. These properties should be taken into account during the development of new toxin-derived peptide drugs, and for the efficient and safe use of the clinically approved drugs from this group in the individual patients.

External evaluation of population pharmacokinetic models for ciclosporin in adult renal transplant recipients

AIMS

Several population pharmacokinetic (popPK) models for ciclosporin (CsA) in adult renal transplant recipients have been constructed to optimize the therapeutic regimen of CsA. However, little is known about their predictabilities when extrapolated to different clinical centres. Therefore, this study aimed to externally evaluate the predictive ability of CsA popPK models and determine the potential influencing factors.

METHODS

A literature search was conducted and the predictive performance was determined for each selected model using an independent data set of 62 patients (471 predose and 500 2-h postdose concentrations) from our hospital. Prediction-based diagnostics and simulation-based normalized prediction distribution error were used to evaluate model predictability. The influence of prior information was assessed using Bayesian forecasting. Additionally, potential factors influencing model predictability were investigated.

RESULTS

Seventeen models extracted from 17 published popPK studies were assessed. Prediction-based diagnostics showed that ethnicity potentially influenced model transferability. Simulation-based normalized prediction distribution error analyses indicated misspecification in most of the models, especially regarding variance. Bayesian forecasting demonstrated that the predictive performance of the models substantially improved with 2-3 prior observations. The predictability of nonlinear Michaelis-Menten models was superior to that of linear compartmental models when evaluating the impact of structural models, indicating the underlying nonlinear kinetics of CsA. Structural model, ethnicity, covariates and prior observations potentially affected model predictability.

CONCLUSIONS

Structural model is the predominant factor influencing model predictability. Incorporation of nonlinear kinetics in CsA popPK modelling should be considered. Moreover, Bayesian forecasting substantially improved model predictability.

Population pharmacokinetics of cyclosporine A in Japanese renal transplant patients: comprehensive analysis in a single center

PURPOSE

Cyclosporine A (CyA), a potent immunosuppressive agent used in renal transplantation, has a narrow therapeutic window and a large variability in blood concentrations. This study aimed to develop a population pharmacokinetic (PPK) model of CyA in living-donor renal transplant patients at a single center and identify factors influencing CyA pharmacokinetics (PK).

METHODS

A total of 660 points (preoperative) and 4785 points (postoperative) of blood concentration data from 98 patients who underwent renal transplantation were used. Pre- and postoperative CyA model structure and PPK parameters were separately estimated with a non-linear mixed-effect model, and subsequently, covariate analysis of postoperative data were comprehensively estimated, including preoperative PK parameters.

RESULTS

A two-compartment model with first-order absorption and absorption lag time was selected in this study. Aspartate aminotransferase, body surface area (BSA), pretransplant area under the whole blood concentration-time curve/dose, and postoperative days were identified as the covariates on oral clearance. BSA was selected as a covariate of the distribution volume of the central compartment. In addition, diabetes mellitus was selected as a covariate of the first-order absorption rate.

CONCLUSIONS

This PPK study used the largest number of blood concentration data among previous reports of living-donor renal transplant patients. Moreover, all patients received the same immunosuppressive regimen in a single center. Therefore, the validity of the selected covariates is reliable with high precision. The developed PPK model and selected covariates provide useful information about factors influencing CyA PK and greatly contributes to the identification of the most suitable dosing regimen for CyA.

Computational analysis of calculated physicochemical and ADMET properties of protein-protein interaction inhibitors

The modulation of PPIs by low molecular weight chemical compounds, particularly by orally bioavailable molecules, would be very valuable in numerous disease indications. However, it is known that PPI inhibitors (iPPIs) tend to have properties that are linked to poor Absorption, Distribution, Metabolism, Excretion and Toxicity (ADMET) and in some cases to poor clinical outcomes. Previously reported in silico analyses of iPPIs have essentially focused on physicochemical properties but several other ADMET parameters would be important to assess. In order to gain new insights into the ADMET properties of iPPIs, computations were carried out on eight datasets collected from several databases. These datasets involve compounds targeting enzymes, GPCRs, ion channels, nuclear receptors, allosteric modulators, oral marketed drugs, oral natural product-derived marketed drugs and iPPIs. Several trends are reported that should assist the design and optimization of future PPI inhibitors, either for drug discovery endeavors or for chemical biology projects.

Pharmacokinetics and pharmacodynamics of immunosuppressive drugs in elderly kidney transplant recipients

Elderly patients are a fast growing population among transplant recipients over the past decades. Both the innate and adaptive immune reactivity decrease with age, which is believed to contribute to the decreased incidence of acute rejection and increased infectious death rate in elderly transplant recipients. In contrast to recipient age, donor age is associated with a higher incidence of acute rejection. Pharmacokinetic studies in renal transplant recipients show that CNI troughs are >5% higher in elderly compared to younger patients given the same dose normalized by body weight. This may impact the starting dose of tacrolimus and cyclosporine. Possibly in elderly patients the intracellular (in lymphocyte) concentrations are relatively high in relation to the whole blood concentration, resulting in a stronger pharmacodynamic effect at the same whole blood trough concentration. For cyclosporine this has been shown, but it is not clear if the same is true for other immunosuppressive drugs. Pharmacodynamic studies have compared the inhibition of target enzymes, or more downstream effects of immunosuppressive drugs, in younger and older patients. Measurement of nuclear factor of activated T-cell (NFAT)-regulated gene expression (RGE), a pharmacodynamic read-out of CNI, is a promising biomarker of immunosuppression. Low levels of NFAT RGE are associated with increased risk of infection and non-melanoma skin cancer in elderly patients. Clinical trials to evaluate the safety and efficacy of immunosuppression regimens in this specific patient population, which is underrepresented in published trials, are lacking. More studies in elderly patients are needed to investigate the impact of age on the pharmacokinetics or pharmacodynamics of immunosuppressive drugs, and to decide on the optimal regimen and target levels for elderly transplant recipients.

Population pharmacokinetics and individualized dosage prediction of cyclosporine in allogeneic hematopoietic stem cell transplant patients

BACKGROUND

Cyclosporine (CsA), a potent immunosuppressive agent used to prevent rejection, is characterized by large individual variability. The purpose of this study was to explore the pharmacokinetic characteristics of CsA and establish a CsA population pharmacokinetic model that could be used for personalized therapy in allogeneic hematopoietic stem cell transplant (allo-HSCT) patients.

METHODS

Clinical data were obtained from 117 allo-HSCT patients. The data analysis was performed using NONMEM software. A first-order conditional estimation with interaction (FOCE-I) method within NONMEM was used to estimate the parameters. The covariates, including demographics, hematological indices, biochemical levels, concurrent drugs, and genetic polymorphisms of CYP3A4, CYP3A5, and ABCB1, were evaluated quantitatively. The stability of the final model was validated by a nonparametric bootstrap procedure.

RESULTS

A total of 1,571 observed concentrations were collected. A 1-compartment model with first-order absorption and elimination adequately described the pharmacokinetics of CsA. The typical values for clearance (CL), volume of distribution (V), and bioavailability were 29.6 L/hr, 605 L, and 0.619, respectively. The interindividual variability of these parameters was 20.4, 66.1, and 30.4%, respectively. The residual error was 31.4% and 23.7 ng/mL. The duration of CsA therapy, hematocrit, antifungal agent administration, triglycerides, and weight were identified as the main covariates that influenced CL, and hematocrit had a significant effect on V. The internal validation showed that the final model was stable and accurate.

CONCLUSIONS

This study established a population pharmacokinetic model of CsA in allo-HSCT patients that could provide the foundation for personalized use of CsA in the clinic.

Early non-steady-state population pharmacokinetics of oral cyclosporine in renal transplant recipients

This study aimed to evaluate the change in the pharmacokinetics (PK) of cyclosporine in the non-steady-state period in the first week after renal transplantation; the factors influencing this change, including genetic variability; and the time point concentration that correlated best with drug exposure. Data were obtained from 69 patients, and PK studies were conducted on postoperative days (PODs) 2, 3, and 7. Samples were taken pre-dose and at 1, 2, 3, 4, 6, 8, and 12 hours after drug administration. MDR1, CYP3A4, and CYP3A5 were genotyped. A population PK analysis and correlational analysis between the concentration at each time point and the area under the time-concentration curve were performed. A two-compartment model with first-order absorption was chosen. The rate and extent of drug absorption showed a significant increase on POD3, followed by a slight decrease on POD7. Until POD3, 8 hours post-dose was the single time point concentration that correlated best with drug exposure and 3 hours was the best time point on POD7. In both analyses, the MDR1 genotype showed potential as a factor influencing PK change. We conclude that oral administration of cyclosporine and dose adjustment based on a single concentration measurement might result in unexpected drug exposure during this early posttransplantation period.

Population pharmacokinetics of cyclosporine in transplant recipients

A number of classical pharmacokinetic studies have been conducted in transplant patients. However, they suffer from some limitations, for example, (1) the study design was limited to intense blood sampling in small groups of patients during a certain posttransplant period, (2) patient factors were evaluated one at a time to identify their association with the pharmacokinetic parameters, and (3) mean pharmacokinetic parameters often cannot be precisely estimated due to large intraindividual variability. Population pharmacokinetics provides a potential means of addressing these limitations and is a powerful tool to evaluate the magnitude and consistency of drug exposure. Population pharmacokinetic studies of cyclosporine focused solely on developing limited sampling strategies and Bayesian estimators to estimate drug exposure, have been summarized before, and are, therefore, not a subject of this review. The major focus of this review is to describe factors (demographic factors, hepatic and gastrointestinal functions, drug-drug interactions, genetic polymorphisms of drug metabolizing enzymes and transporters) that have been identified to contribute to the large portion of observed variability in the pharmacokinetics of cyclosporine in transplant patients. This review summarizes and interprets the conclusions as well as the nonlinear mixed-effects modeling methodologies used in such studies. A highly diversified collection of structural models, variability models, and covariate submodels have been evaluated and validated using internal or external validation methods. This review also highlights areas where additional research is warranted to improve the models since a portion of model variability still remains unexplained.

Population-Based Assessments of Clinical Drug-Drug Interactions: Qualitative Indices or Quantitative Measures?

Population-based assessments of drug-drug interactions have become more common since the introduction and acceptance of the population pharmacokinetic approach. Unlike traditional methods, population-based studies provide clinically relevant results that can be applied directly to a target patient population. Furthermore, population-based studies do not demand the traditional requirements of intensive pharmacokinetic sampling, rigorous inpatient stays, or stringent assessment schedules. As such, the population-based approach can effectively be used to confirm known drug-drug interactions and further characterize anticipated interactions. A prospectively designed analysis can also reveal drug-drug interactions that might otherwise have gone undetected with traditional methods. Ultimately, these results could help to alleviate clinicians' concerns about using widely marketed drugs in combination therapies and also reduce patients' risk of experiencing unacceptable side effects. This article intends to provide a balanced overview of the population-based approach and its merits, drawbacks, and potential utility in the assessment of drug-drug interactions during clinical drug development.

Nonlinear population pharmacokinetics of sirolimus in patients with advanced cancer

Sirolimus, the prototypical inhibitor of the mammalian target of rapamycin, has substantial antitumor activity. In this study, sirolimus showed nonlinear pharmacokinetic characteristics over a wide dose range (from 1 to 60 mg/week). The objective of this study was to develop a population pharmacokinetic (PopPK) model to describe the nonlinearity of sirolimus. Whole blood concentration data, obtained from four phase I clinical trials, were analyzed using a nonlinear mixed-effects modeling (NONMEM) approach. The influence of potential covariates was evaluated. Model robustness was assessed using nonparametric bootstrap and visual predictive check approaches. The data were well described by a two-compartment model incorporating a saturable Michaelis–Menten kinetic absorption process. A covariate analysis identified hematocrit as influencing the oral clearance of sirolimus. The visual predictive check indicated that the final pharmacokinetic model adequately predicted observed concentrations. The pharmacokinetics of sirolimus, based on whole blood concentrations, appears to be nonlinear due to saturable absorption.

CYP3A5 polymorphism effect on cyclosporine pharmacokinetics in living donor renal transplant recipients: analysis by population pharmacokinetics

BACKGROUND

Cyclosporine is often used to prevent allograft rejection in renal transplant recipients. However, cyclosporine has a narrow therapeutic window and large variability in its pharmacokinetics. Individual characteristics and genetic polymorphisms can cause the variation. Hence, it is important to determine the cause(s) of the variation in cyclosporine pharmacokinetics. To our knowledge, this is the first reported population pharmacokinetic study of cyclosporine in living donor renal transplant recipients that considered the genetic polymorphism as a covariate.

OBJECTIVE

To build a population pharmacokinetic model of cyclosporine in living donor renal transplant recipients and identify covariates including CYP3A5*3, ABCB1 genetic polymorphisms that affect cyclosporine pharmacokinetic parameters.

METHODS

Clinical characteristics and cyclosporine concentration data for 69 patients who received cyclosporine-based immunosuppressive therapy after living donor renal transplantation were collected retrospectively for up to 400 postoperative days. CYP3A5*1/*3 and ABCB1C1236T, G2677T/A, C3435T geno-typing was performed. A population pharmacokinetic analysis was conducted using a NONMEM program. After building the final model, 1000 bootstrappings were performed to validate the final model.

RESULTS

In total, 2034 blood samples were collected. A 1-compartment open model with first-order absorption and elimination was chosen to describe the pharmacokinetics of cyclosporine. A population pharmacokinetic analysis showed that postoperative days, sex, and CYP3A5 genotype significantly affected the pharmacokinetics of cyclosporine. The final estimate of mean clearance was 56 L/h, and the mean volume of distribution was 4650 L. The interindividual variability for these parameters was 22.98% and 51.48%, respectively.

CONCLUSIONS

Using the present model to calculate the dose of cyclosporine with CYP3A5 genotyping can be possible for the patients whose cyclosporine concentration is not within the therapeutic range even with therapeutic drug monitoring.

Population pharmacokinetics of ciclosporin in haematopoietic allogeneic stem cell transplantation with emphasis on limited sampling strategy

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT • The population pharmacokinetics and limited sampling strategies for ciclosporin monitoring have been extensively studied in renal and liver transplant recipients. Little is known about the pharmacokinetics of ciclosporin in patients undergoing haematopoietic allogeneic stem cell transplantation (HSCT). • It is anticipated that there is a difference in pharmacokinetics in patients after kidney or liver transplantation compared with patients undergoing stem cell transplantation, because of mucositis and interacting drugs (e.g. fluconazole). • Data on the pharmacokinetics of ciclosporin and the relationship between its systemic exposure, as reflected by the area under the curve (AUC), and the biological effect as graft vs. host-disease (GVHD) prophylaxis and graft vs. tumour (GVT) response are scarce in patients after HSCT. WHAT THIS STUDY ADDS • A pharmacokinetic model was developed for orally and intravenously administered ciclosporin, enabling an adequate estimate of the systemic exposure of ciclosporin in patients after HSCT. A limited sampling strategy was tested that may serve as a tool to study the optimum systemic exposure (AUC) of ciclosporin in HSCT to prevent GVHD but establish adequate GVT response and to guide therapeutic drug monitoring. AIM To develop a population pharmacokinetic model of ciclosporin (CsA) in haematopoietic allogeneic stem cell transplantation to facilitate a limited sampling strategy to determine systemic exposure (area under the curve [AUC]), in order to optimize CsA therapy in this patient population. METHODS The pharmacokinetics of CsA were investigated prospectively in 20 patients following allogeneic haematopoietic stem cell transplantation (HSCT). CsA was given twice daily, as a 3 h i.v. infusion starting at day 1 of the conditioning scheme, and orally later on, when oral intake was well tolerated. Fluconazole was given as antimycotic prophylaxis. Pharmacokinetic parameter estimation was performed using nonlinear mixed effect modelling as implemented in the NONMEM program. A first order absorption model with lag time was compared with Erlang frequency distribution and Weibull distribution models. The influence of demographic variables on the individual empirical Bayesian estimates of clearance and distribution volume was tested. Subsequently two limited sampling strategies (LSS) were evaluated: posterior Bayesian fitting and limited sampling equations. RESULTS Twenty patients were included and 435 samples were collected after i.v. and oral administration of CsA. A two compartment model with first order absorption best described the data. Clearance (CL) was 21.9 l h(-1) (relative standard deviation [RSD]± 5.2%) with an inter-individual variability of 21%. The central volume of distribution (V(c) ) was 18.3 l (RSD ± 8.7%) with an inter-individual variability of 29%. Bioavailability (F) was 0.71 (RSD ± 9.9%) with and inter-individual variability of 25% and lag time (t(lag) ) was 0.44 h (RSD 5.5%). Weight, body surface area, haematocrit, albumin, ALAT and ASAT had no significant influence on pharmacokinetic parameters. The best multiple point combination for posterior Bayesian fitting, in terms of estimating systemic CsA exposure, appeared to be C0 + C2 + C3. Two selected LSS two time point equations and all selected three and four time point equations predicted de all AUC(0,12 h) within 15% bias and prediction. CONCLUSIONS The i.v. and oralcurves were best described with a two compartment model with first-order absorption with lag time. With the Bayesian estimators from this model, the area under the concentration-time curve in HSCT patients taking fluconazole can be estimated with only three blood samples (0, 2, 3 h) with a bias of 1% and precision of 4%.

Modeling rejection immunity

Background

Transplantation is often the only way to treat a number of diseases leading to organ failure. To overcome rejection towards the transplanted organ (graft), immunosuppression therapies are used, which have considerable side-effects and expose patients to opportunistic infections. The development of a model to complement the physician’s experience in specifying therapeutic regimens is therefore desirable. The present work proposes an Ordinary Differential Equations model accounting for immune cell proliferation in response to the sudden entry of graft antigens, through different activation mechanisms. The model considers the effect of a single immunosuppressive medication (e.g. cyclosporine), subject to first-order linear kinetics and acting by modifying, in a saturable concentration-dependent fashion, the proliferation coefficient. The latter has been determined experimentally. All other model parameter values have been set so as to reproduce reported state variable time-courses, and to maintain consistency with one another and with the experimentally derived proliferation coefficient.

Results

The proposed model substantially simplifies the chain of events potentially leading to organ rejection. It is however able to simulate quantitatively the time course of graft-related antigen and competent immunoreactive cell populations, showing the long-term alternative outcomes of rejection, tolerance or tolerance at a reduced functional tissue mass. In particular, the model shows that it may be difficult to attain tolerance at full tissue mass with acceptably low doses of a single immunosuppressant, in accord with clinical experience.

Conclusions

The introduced model is mathematically consistent with known physiology and can reproduce variations in immune status and allograft survival after transplantation. The model can be adapted to represent different therapeutic schemes and may offer useful indications for the optimization of therapy protocols in the transplanted patient.

Population pharmacokinetics of cyclosporine A based on NONMEM in Chinese allogeneic hematopoietic stem cell transplantation recipients

To set up a population pharmacokinetic (PPK) model of cyclosporine A (CsA) in Chinese allogeneic hematopoietic stem cell transplantation (allo-HSCT) patients to provide reference for individualized medication in clinical practice. 281 trough plasma concentrations of CsA and covariates such as demographics, clinical laboratory values and coadministration were retrospectively collected from 73 allo-HSCT patients. Population modeling was performed using general model of NONMEM expressed by differential equation. Hematocrit (HCT), plasma albumin (ALB) level, and coadministration of itraconazole (ITR) were found to significantly affect the clearance of CsA (CL, L/h). The final model formula was: CL = 28.2 × [1 - 0.0263 × (HCT - 26.62)] × [1 - 0.0289 × (ALB - 37.63)] × [1 - 0.146 × ITR] (L/h); V = 1,080 (L); K (a) = 1.28 (h⁻¹); F = 0.711. The interindividual variabilities for CL, V and F were 21.4, 41.5 and 6.07 %, respectively. The residual error was 0.00422 mg/L. The PPK model was validated to be effective and stable by bootstrap method. Clinical applications showed there was a good linear correlation between the predicted concentrations and the observed (y = 1.0095x + 0.0082, r = 0.9309, p < 0.0001). The PPK final model of CsA in Chinese allo-HSCT patients can be established using the NONMEM program which can be applied in clinical allo-HSCT practice when characteristics of patients fit in with those of subpopulation in the study.

Pharmacogenetics of calcineurin inhibitors in Brazilian renal transplant patients

AIM

Polymorphisms in the CYP3A5 and ABCB1 genes have been investigated as modulators of the pharmacokinetics and clinical effects of cyclosporine (CSA) and tacrolimus (TAC) in European, North American and Asian populations, with controversial results. The extensive variation in worldwide frequency distribution of CYP3A5 and ABCB1 polymorphisms is a caveat against the extrapolation of these data to the heterogeneous and admixed Brazilian population. We investigated the effect of CYP3A5 and ABCB1 polymorphisms on CSA and TAC dose-adjusted trough concentration (C₀/dose) in Brazilian renal transplant recipients, during the first 3 months post-transplantation.

MATERIALS & METHODS

Patients receiving CSA (n = 150) or TAC (n = 151) were genotyped for CYP3A5*3 (rs776746, 6986A>G), *6 (rs10264272, 14690G>A) and *7 (rs41303343, 27131-27132insT) and for ABCB1 1236C>T (rs1128503), 2677G>T/A (rs2032582) and 3435C>T (rs1045642) polymorphisms. We explored the effects of CYP3A5 and ABCB1 polymorphisms, clinical and demographical characteristics on CSA and TAC C₀/dose under a two-step data analysis strategy by fitting a longitudinal mixed-effects model to the data; first to select the important covariates under a univariate setting and then to fit the final multivariate model.

RESULTS

C₀/dose of TAC was associated with the number of CYP3A5-defective alleles, in a gene-dose manner, throughout the observation period, whereas C₀/dose of CSA was associated with body surface area and prednisone dosing. No other significant associations were detected.

CONCLUSION

Individual adjustment of the initial TAC dose according to the CYP3A5 haplotypes comprising the CYP3A5*3, *6 and *7 defective alleles might prove beneficial to Brazilian renal transplant recipients and should be further investigated in prospective trials.

Race differences: modeling the pharmacodynamics of rosuvastatin in Western and Asian hypercholesterolemia patients

AIM

To evaluate race differences in the pharmacodynamics of rosuvastatin in Western and Asian hypercholesterolemia patients using a population pharmacodynamic (PPD) model generated and validated using published clinical efficacy trials.

METHODS

Published studies randomized trials with rosuvastatin treatment for at least 4 weeks in hypercholesterolemia patients were used for model building and validation. Population pharmacodynamic analyses were performed to describe the dose-response relationship with the mean values of LDL-C reduction (%) from dose-ranging trials using NONMEM software. Baseline LDL-C and race were analyzed as the potential covariates. Model robustness was evaluated using the bootstrap method and the data-splitting method, and Monte Carlo simulation was performed to assess the predictive performance of the PPD model with the mean effects from the one-dose trials.

RESULTS

Of the 36 eligible trials, 14 dose-ranging trials were used in model development and 22 one-dose trials were used for model prediction. The dose-response of rosuvastatin was successfully described by a simple E(max) model with a fixed E(0), which provided a common E(max) and an approximate twofold difference in ED(50) for Westerners and Asians. The PPD model was demonstrated to be stable and predictive.

CONCLUSION

The race differences in the pharmacodynamics of rosuvastatin are consistent with those observed in the pharmacokinetics of the drug, confirming that there is no significant difference in the exposure-response relationship for LDL-C reduction between Westerners and Asians. The study suggests that for a new compound with a mechanism of action similar to that of rosuvastatin, its efficacy in Western populations plus its pharmacokinetics in bridging studies in Asian populations may be used to support a registration of the new compound in Asian countries.

Computer-assisted cyclosporine dosing performs better than traditional dosing in renal transplant recipients: results of a pilot study

Cyclosporine A (CsA) is widely used after organ transplantation. Its narrow therapeutic window and large pharmacokinetic variability makes therapeutic drug monitoring (TDM) demanding and frequent dose adjustments are needed, especially early after transplantation. The aim of the present pilot study was to compare accuracy of CsA TDM by experienced clinicians against a computer-assisted dosing model. Renal transplant recipients on CsA, prednisolone, and mycophenolate were included 2 weeks after transplantation, randomized (1:1) to either computer dosing (MAP-BE) or control (CONTR) and followed for at least 8 weeks. A maximum a posteriori probability Bayesian estimation method, applying a population pharmacokinetic model and the POSTHOC option in nonlinear mixed effects modeling, was used to individualize CsA doses in the MAP-BE group. Forty patients (31 men, 27.5% living donor) between 28 and 80 years were included. A total of 798 CsA concentration measurements and adherent dosing evaluations/adjustments were performed. During the entire study, blood concentrations were on average 10% +/- 5% from the predefined therapeutic target range in the MAP-BE group, as compared with 13% +/- 8% in the CONTR group (P = 0.042). However, there was no significant difference between groups regarding the percentage of CsA concentrations truly within the therapeutic windows [MAP-BE: 37% +/- 17%, CONTR: 33% +/- 15% (P = 0.57)] or in CsA dose [MAP-BE: 3.55 +/- 0.8, CONTR: 3.90 +/- 0.9 mg/kg/d (P = 0.26)]. Acute rejections were present in 4 and 3 patients, respectively (P = 1.00). The computer-assisted TDM-targeted CsA blood concentrations significantly better than experienced transplant physicians. A possible favorable effect on short- and long-term outcome needs to be verified in further, properly powered, clinical trials.

Individualized Neoral doses in pediatric renal transplantation

We propose a model to calculate individualized Neoral doses based on individual oral clearance (CL/F)(i) and AUC((0-12h)) values. The equation proposed by Dr. Ke-Hua Wu (2005), was employed to calculate the CL/F(i) = 28,5 - (1.24*POD) - 0.252*(TBil-11) + 0,188*(Weight o-58) -0,191*(Age-42) - 2,42*INHI - 0,212*(HCT-28), where CI/F = (L/h), POD = postoperative days, Bil.T = total bilirubin level (umol/L), CBW = in kilograms, age = in years, INHI = concurrent metabolic inhibitors present (1) or absence (0), and HCT = hematocrit percentage. The AUC((0-12h)) was calculated from the C(2) value using the equation AUC((0-12h)) = 815,578 + 4,44696*C(2), derived from the linear correlation observed in earlier work at Clinica Las Condes Hospital. The studied population were 30 kidney transplanted children at Luis Calvo Mackenna Hospital, between 2002 and 2006, who were divided into 2 similar groups according to accurate C(2) sampling time collections. The control group 1 was composed of 13 patients of age 9.85 +/- 4 years whose samples were collected correctly. Group 2 was composed of 17 patients of age 10.43 +/- 6 years with 252 C(2) samples, which were obtained at medical control. All patients were under oral treatment with prednisone, azathioprine, nifedipine, and Neoral administered twice day according the weight of the patient and the C(2) level. Relating Neoral administered doses to calculated doses according to the proposed model, the control group showed a linear correlation coefficient r = 0.924; r(2) = 85.4%; (P < .05), and group 2, r = 0.54; r(2) = 29.1 (P < .05). The proposed model to calculate Neoral doses had a predictive value of 85.0% when C(2) samples were collected correctly.

A population pharmacokinetic model of ciclosporin applicable for assisting dose management of kidney transplant recipients

BACKGROUND AND OBJECTIVE

The pharmacokinetic disposition of ciclosporin shows great intra- and interpatient variability, and that combined with a narrow therapeutic window makes therapeutic drug monitoring of ciclosporin necessary. The nonlinear mixed-effects population pharmacokinetic program NONMEM predicts individual pharmacokinetic parameters based not only on individual patient observations but also on population characteristics and the patient's covariates. The aim of this model development is to potentially use it in the clinical setting to optimize ciclosporin dosing in renal transplant recipients.

METHODS

A population pharmacokinetic model of ciclosporin has been developed with NONMEM using full 12-hour pharmacokinetic profiles from 29 renal transplant recipients, 3 months of daily follow-up data from an additional 11 recipients, and both 3 months of follow-up data and full 12-hour pharmacokinetic profiles from nine patients. The internal validation of the model was based on data splitting and jack-knife methods. In addition, the model was validated for its clinical applicability on standard trough and 2-hour post-dose concentration data from 12 additional patients with 3 months of follow-up.

RESULTS

The model that best described the ciclosporin data was a two-compartment model with first-order absorption process with lagged time. The population pharmacokinetic parameters were oral clearance (CL/F) = 26.9 L/h; central volume of distribution after oral administration (V(1)/F) = 24.4 L; absorption rate constant (k(a)) = 0.544 h-1; lag time = 0.460 h; peripheral volume of distribution = 1119 L and intercompartmental clearance after oral administration (Q/F) = 19.6 L/h. Three covariates had significant effect on a total of six pharmacokinetic parameters. These were bodyweight on V(1)/F and k(a), time after transplantation on k(a), and age on CL/F, k(a) and V(1)/F. Cytochrome P450 3A5 genotype was also a significant covariate but was not included in the final model since such information is not available in clinical practice. The external validation showed that the model was able to predict ciclosporin concentrations in the 12 new patients with an average predictive error of 17.4 +/- 14% when the standard sample concentrations from the previous week were given.

CONCLUSION

A NONMEM pharmacokinetic model for ciclosporin in renal transplant recipients was successfully developed and validated for the first 3 months post-transplantation. The model showed good predictability in a new patient cohort. After further clinical validation, the model may be applicable as a clinical tool for optimizing ciclosporin dosing in renal transplant recipients in the early post-transplant period.

Population pharmacokinetic study of cyclosporine in patients with nephrotic syndrome

Cyclosporine (CsA) is widely used in the treatment of nephrotic syndrome (NS). A population pharmacokinetic (PopPK) model was developed using trough blood CsA concentration data from 106 patients with NS. The pharmacokinetic analysis was performed using NONMEM with 1-compartment linear model and first-order elimination. Proportional and additive error models were used to describe the interindividual and intraindividual variabilities, respectively. Body weight (WT), serum albumin level (ALB), and combination therapy with rifampicin were found to be the most significant covariates explaining the variability of the apparent clearance (CL/F) of CsA among patients. The final model was as follows: TVCL/F=34.1x(WT/67.6)(1.08)x(1+RFAx0.67)x(1-ALBx0.0088); TVV/F=3.5xWT; Ka=1.28 fixed; where RFA=1 with concurrent rifampicin use and 0 otherwise. The interindividual variabilities of CL/F and V/F were 18% and 27%, respectively. The residual error was 0.064 mg/L. The mean+/-SD of CL/F and V/F of the 106 patients were 23.5+/-7.2 L/h and 232.3+/-71.5 L, respectively. The reliability and stability of the PopPK model were confirmed by nonparametric bootstrap procedure.

Prolongation of cardiac allograft survival by syngeneic hematopoietic stem/progenitor cell transplantation in mice

INTRODUCTION

Organ transplantation is a rapidly developing field, being the only effective treatment for end-stage organ disease. However, the associated immunosuppressant therapy has numerous direct and indirect adverse effects. Hematopoietic stem cell transplantation (HSCT), via immune reconstitution, offers an alternative method of treatment. In this study, we determined the cardiac allograft survival in mice treated with syngeneic HSCT or hematopoietic progenitor cell transplantation (HPCT).

METHODS

BALB/c and C57BL/6 mice were randomly divided into three groups. Mice in Group A (n=7) were untreated while those in Group B (n=8) and C (n=7) were treated with HPCT and HSCT, respectively. Cervical heterotopic cardiac transplantation models were established in all groups and cardiac grafts were observed throughout. Regulatory T (Treg) cell expression in peripheral blood was analyzed by flow cytometry. We recorded the cardiac allograft survival time and constructed Kaplan-Meier survival curves.

RESULTS

The number of Treg cells in Group B was significantly higher than that in Group C (P<0.05). The survival time of mice from each group differed significantly according to Kaplan-Meier/log-rank analysis (P<0.01). A total of 62.5% of the grafts in Group B showed long-term survival (>100 days); all the mice in Group A died within 9 days, compared with 59 days in Group C.

CONCLUSION

We conclude that syngeneic HSCT and HPCT can prolong cardiac allograft survival in mice. These two methods could be promising ways to induce immune tolerance in future organ transplantation.

Developmental pharmacokinetics of ciclosporin--a population pharmacokinetic study in paediatric renal transplant candidates

AIMS

To use population pharmacokinetic modelling to characterize the influence of developmental and demographic factors on the pharmacokinetic variability of ciclosporin.

METHODS

Pharmacokinetic modelling was performed in NONMEM using a dataset comprising 162 pretransplant children, aged 0.36-17.5 years. Ciclosporin was given intravenously (3 mg kg(-1)) and orally (10 mg kg(-1)) on separate occasions followed by blood sampling for 24 h.

RESULTS

A three-compartment model with first-order absorption without lag-time best described the pharmacokinetics of ciclosporin. The most important covariate affecting systemic clearance (CL) and distribution volume (V) was body weight (BW; scaled allometrically), responsible for a fourfold difference in uncorrected ciclosporin CL and a sixfold difference in ciclosporin V. The other significant covariates, haematocrit, plasma cholesterol and creatinine, were estimated to explain 20-30% of interindividual differences in CL and V of ciclosporin. No age-related changes in oral bioavailability or in BW-normalized V were seen. The BW-normalized CL (CL/BW) declined with age and prepubertal children (<8 years) had an approximately 25% higher CL/BW than did older children. Normalization of CL for allometric BW (BW(3/4)) removed its relationship to age.

CONCLUSION

The relationship between CL and allometric BW is consistent with a gradual reduction in relative liver size, until adult values, and a relatively constant CYP3A4 content in the liver from about 6-12 months of age to adulthood. Ciclosporin oral bioavailability, known previously to display large interindividual variability, is not influenced by age. These findings can enable better individualization of ciclosporin dosing in infants, children and adolescents.

[A case report of unresectable gallbladder cancer that responded remarkably to the combination of thalidomide, celecoxib, and gemcitabine]

Gallbladder cancer is an asymptomatic disease in the early stage and no therapeutic measure is available except surgical intervention. The prognosis for patients with advanced,i.e., unresectable or metastatic disease is dismal, with median survival usually being less than 6 months if not treated with chemotherapy. To date, chemotherapy for gallbladder cancer has been limited by the absence of agents with effective cytotoxic activity. Thalidomide has been shown to have antiangiogenic and immunomodulatory effects, including the inhibition of vascular endothelial growth factor, basic fibroblast growth factor and tumor necrosis factor alpha. Celecoxib is a potent selective COX-2 inhibitor. The reported biological consequences of COX-2 up-regulation include inhibition of apoptosis, increased metastatic potential and promotion of angiogenesis. These events may contribute to cell transformation and tumor progression. Antiangiogenesis represents a significant new strategy for cancer treatment. Therefore,it is important to accept a wide range of different inhibitors such as thalidomide and selective COX-2 inhibitors with conventional cytotoxic agents. Here we show a case of unresectable gallbladder cancer with remarkable improvement in CA19-9 and prolongation of life.