C-Reactive Protein as an Early Predictor of Efficacy in Advanced Non-Small-Cell Lung Cancer Patients: A Tumor Dynamics-Biomarker Modeling Framework.

In oncology, longitudinal biomarkers reflecting the patient's status and disease evolution can offer reliable predictions of the patient's response to treatment and prognosis. By leveraging clinical data in patients with advanced non-small-cell lung cancer receiving first-line chemotherapy, we aimed to develop a framework combining anticancer drug exposure, tumor dynamics (RECIST criteria), and C-reactive protein (CRP) concentrations, using nonlinear mixed-effects models, to evaluate and quantify by means of parametric time-to-event models the significance of early longitudinal predictors of progression-free survival (PFS) and overall survival (OS). Tumor dynamics was characterized by a tumor size (TS) model accounting for anticancer drug exposure and development of drug resistance. CRP concentrations over time were characterized by a turnover model. An x-fold change in TS from baseline linearly affected CRP production. CRP concentration at treatment cycle 3 (day 42) and the difference between CRP concentration at treatment cycles 3 and 2 were the strongest predictors of PFS and OS. Measuring longitudinal CRP allows for the monitoring of inflammatory levels and, along with its reduction across treatment cycles, presents a promising prognostic marker. This framework could be applied to other treatment modalities such as immunotherapies or targeted therapies allowing the timely identification of patients at risk of early progression and/or short survival to spare them unnecessary toxicities and provide alternative treatment decisions.

Pharmacometrics enhanced Bayesian borrowing approach to improve clinical trial efficiency: Case of empagliflozin in type 2 diabetes.

We report use of a pharmacometrics enhanced Bayesian borrowing (PEBB) approach to leverage historical clinical trial data on a drug product to build models, project the outcome of future clinical trials, and borrow information from these projections to improve the efficiency of future target trials. This design takes a two-stage approach. First, a design phase is performed before target trial data are available to determine the operating characteristics and an appropriate tuning parameter that will be used in the subsequent analysis phase of a chosen target trial. Second, once the target trial data are available, the analysis phase is performed with the determined tuning parameter. This step is where borrowing is applied from these projections to inform the results for the target trial. To illustrate how a PEBB could improve the efficiency of clinical trials, we apply our design to trials with empagliflozin for treating patients with type 2 diabetes. We performed a retrospective evaluation applying the method to a phase III target trial and a hypothetical smaller trial. The type I error could be kept below 10% while increasing the trial power and effective sample size. Our findings suggest that a PEBB has the potential to increase the power of clinical trials, while controlling for type I error, by leveraging the information from previous trials through population pharmacokinetic/pharmacodynamic modeling and simulation.

An Innovative Pharmacometric Approach for the Simultaneous Analysis of Frequency, Duration and Severity of Migraine Events.

PURPOSE: To explore the use of a multistate repeated, time-to-categorical event model describing the frequency, severity and duration of migraines. METHODS: Subject level data from patients in placebo arms from two efficacy trials for migraine-preventive treatments were used. Models were developed using NONMEM 7.3. A survival model was combined with an ordered categorical model to form the repeated-time-to-start of categorical migraine event model, which simultaneously described the time-to-start of migraines and the severity of the starting migraine event. This was linked to a repeated-time-to-end of migraine event model with different hazard functions depending on the severity of the ongoing migraine event. Model performance was internally and externally qualified. RESULTS: The successfully qualified model showed that patients responding to placebo had a reduction in migraine incidence rate, and a decreased proportion of severe migraines. There was an increase in moderate migraine duration, an increased proportion of mild migraines and a reduction in proportion of severe migraines. Age was related to migraine duration. CONCLUSIONS: The model represents an innovative framework for clinical trial modeling and simulation, and successfully describes placebo effect in migraine prevention. This approach can be adapted to investigate exposure-response relationship of drugs and can also be implemented in other therapeutic areas where the rate, duration and severity of disease episodes are relevant to trial outcomes.

Pharmacokinetic/Pharmacodynamic Analysis of Voriconazole Against Candida spp. and Aspergillus spp. in Allogeneic Stem Cell Transplant Recipients.

BACKGROUND: To evaluate the adequacy of different dosing regimens of voriconazole for the prophylaxis of invasive candidiasis and aspergillosis in adult allogeneic stem cell transplant recipients by means of population pharmacokinetic (PK) modelling and simulation. METHODS: Allogeneic stem cell transplant recipients receiving voriconazole were included in this observational study. A population PK model was developed. Three oral voriconazole-dosing regimens were simulated: 200, 300, and 400 mg twice daily. The pharmacodynamic target was defined as fAUC0-24/0.7. A probability of target attainment ≥90% was considered optimal. The cumulative fraction of response was defined as the fraction of patients achieving the pharmacodynamic target when a population of simulated patients is matched with a simulated population of different Candida spp. and Aspergillus spp. The percentage of patients with trough plasma concentrations at steady state (Ctrough) within the reference range (1-5.5 mg/L) was also calculated. RESULTS: A 2-compartment PK model was developed using data from 40 patients, which contributed 237 voriconazole plasma samples, including trough and maximum concentrations. Voriconazole 200, 300, and 400 mg twice daily achieved probability of target attainment ≥90% for minimal inhibitory concentration values ≤0.25, ≤0.38, and ≤0.50 mg/L, respectively. The cumulative fraction of response for A. niger, A. versicolor, and A. flavus increased >10% when increasing voriconazole dose from 200 to 400 mg twice daily (from 72.5% to 89.5% for A. niger; from 77.7% to 88.7% for A. versicolor; and from 82.4% to 94.9% for A flavus). The percentage of patients with Ctrough within the reference range increased 15% when voriconazole dose was increased from 200 to 300 mg twice daily. CONCLUSIONS: The PK simulations in this study suggest that transplant recipients on voriconazole prophylaxis against invasive candidiasis or aspergillosis are likely to achieve the target concentrations associated with the desired treatment outcomes if the maintenance dose is 200 mg twice daily. However, Aspergillus spp. with high minimal inhibitory concentrations could require higher maintenance doses.

Effect of Sirolimus Exposure on the Need for Preemptive Antiviral Therapy for Cytomeglovirus Infection after Allogeneic Hematopoietic Stem Cell Transplantation.

The current study evaluates the clinical effect of sirolimus exposure on the occurrence of cytomegalovirus (CMV) DNAemia necessitating preemptive antiviral therapy. A total of 167 consecutive recipients of reduced-intensity conditioning (RIC) allogeneic hematopoietic stem cell transplantation (allo-HSCT) who received sirolimus- and tacrolimus-based graft-versus-host disease (GVHD) prophylaxis and whose CMV serostatus was positive for donors and/or recipients were included in this multicenter retrospective study. A parametric model with consecutive sirolimus blood levels describing the time to CMV DNAemia-RAT was developed using NONMEM version 7.4. Overall, 122 of 167 patients (73%) were allografted from an unrelated donor, and the donor CMV-serostatus was negative in 51 cases (31%). Fifty-six recipients (34%) developed CMV DNAemia necessitating preemptive therapy, with a cumulative incidence of 36% at a median follow-up of 25 months. Time to CMV DNAemia necessitating preemptive therapy was best described using a Gompertz function. CMV DNAemia necessitating preemptive therapy-predicting factors were antithymocyte globulin-based conditioning regimen (hazard ratio [HR], 2.2; 95% confidence interval [CI], 1.1 to 4.1; P < .01) and sirolimus concentration (HR, .94; 95% CI, .87 to .99; P < .01). The risk of CMV DNAemia-RAT decreased by 6% for each 1 ng/mL increase in sirolimus trough concentration. In conclusion, we provide evidence on the association between sirolimus blood concentration and incidence of CMV DNAemia necessitating preemptive therapy in allo-HSCT recipients. Moreover, this study presents the first predictive model describing the time to CMV DNAemia necessitating preemptive antiviral therapy as a function of sirolimus drug concentration.

Sirolimus exposure and the occurrence of cytomegalovirus DNAemia after allogeneic hematopoietic stem cell transplantation.

Sirolimus appears to protect against cytomegalovirus (CMV) in organ transplant recipients. The effect of this drug in allogeneic hematopoietic stem cell transplantation recipients remains unexplored. By means of multivariate continuous-time Markov model analyses, we identified 3 independent covariates that significantly impacted the risk of CMV DNAemia: recipient/donor CMV serostatus, tacrolimus exposure, and sirolimus exposure. CMV-seropositive recipients with CMV-seronegative donors had a significantly higher probability of having detectable CMV DNAemia. Increasing the tacrolimus trough concentration from 0 to 16 ng/mL increased the probability of patients having detectable CMV DNAemia by 40% (from 40% to 80%), whereas this probability decreased by 25% (from 40% to 15%) when trough concentrations of sirolimus increased from 0 to 16 ng/mL. Sensitivity analysis showed that sirolimus exposure between 0 and 6 ng/mL has no or negligible effect on CMV DNAemia, but levels >8 ng/mL significantly decreased the number of detectable CMV DNAemia cases (the risk ratios decreased from 0.68 to 0.21 when whole blood sirolimus concentrations changed from 8 to 18 ng/mL, P < .01). In conclusion, we used a pharmacometric statistical tool to provide the first clinical evidence that fewer CMV DNAemia events become detectable as sirolimus exposure increases.

Dosing of caspofungin based on a pharmacokinetic/pharmacodynamic index for the treatment of invasive fungal infections in critically ill patients on continuous venovenous haemodiafiltration.

INTRODUCTION: The study objective was to evaluate the efficacy of different dosages of caspofungin in the treatment of invasive candidiasis and aspergillosis, in relation to the probability of pharmacokinetic/pharmacodynamic (PK/PD) target attainment, using modelling and Monte Carlo simulations in critically ill adult patients on continuous haemodiafiltration. METHODS: Critically ill adult patients on continuous venovenous haemodiafiltration treated with caspofungin were analysed. A population PK model was developed. Four caspofungin dosing regimens were simulated: the licensed regimen, 70 mg/day, 100 mg/day or 200 mg/day. A PK/PD target was defined as the ratio between the area under the caspofungin concentration-time curve over 24 hours and the minimal inhibitory concentration (AUC/MIC) for candidiasis or the minimal effective concentrations (AUC/MEC) for Aspergillus spp. Target attainment based on preclinical target for Candida and Aspergillus was assessed for different MIC or MEC, respectively. RESULTS: Concentration-time data were described by a two-compartment model. Body-weight and protein concentration were the only covariates identified by the model. Goodness-of-fit plots and bootstrap analysis proved the model had a satisfactory performance. As expected, a higher maintenance dose resulted in a higher exposure. Target attainment was >90% for candidiasis (MIC≤0.06 mg/L) and aspergillosis (MEC≤0.5 mg/L), irrespective of the dosing regimen, but not for C. parapsilosis. Standard regimen was insufficient to reach the target for C. albicans and C. parapsilosis with MIC≥0.1 mg/L. CONCLUSION: The licensed regimen of caspofungin is insufficient to achieve the PK/PD targets in critically ill patients on haemodiafiltration. The determination of MICs will enable dose scheme selection.

Effectiveness of Nivolumab versus Docetaxel as Second-Line Treatment in Non-Small Cell Lung Cancer Patients in Clinical Practice.

AIMS: To evaluate the effectiveness of nivolumab as second-line treatment compared to standard therapy with docetaxel in adult patients with non-small cell lung cancer (NSCLC) in clinical practice. METHODS: This is an observational, retrospective cohort study of adult patients diagnosed with NSCLC, stage III-IV, treated with docetaxel or nivolumab as second-line treatment. The end points evaluated were overall survival (OS) and progression-free survival (PFS). PFS and OS were described using the Kaplan-Meier method. The Cox proportional hazards model was applied to identify independent prognostic and predictive factors related to disease progression or death. RESULTS: Thirty-three patients were included in this study (i.e., 14 in the nivolumab group and 19 in the docetaxel group). Nonsquamous NSCLC was the most frequent histological subtype. Cohorts were homogeneous. The follow-up time was 116 ± 87.3 days. The median PFS was 84 days (95% CI 39-300) for patients treated with nivolumab and 61 days (95% CI 48-76) for patients treated with docetaxel. The risk of progression was 60% lower for patients treated with nivolumab (HR 0.40; 95% CI 0.16-0.97; p = 0.043) compared to patients receiving docetaxel. Among the patients treated with docetaxel, the median OS was 129 days (95% CI 106-300). More than 50% of the patients treated with nivolumab were alive at the end of the follow-up period; nevertheless, the risk difference was not statistically significant (HR 0.55; 95% CI 0.20-1.51; p = 0.244). CONCLUSION: NSCLC patients treated with nivolumab as second-line therapy had a longer PFS compared to patients treated with docetaxel in a health care environment.

A Time-to-Event Model for Acute Kidney Injury after Reduced-Intensity Conditioning Stem Cell Transplantation Using a Tacrolimus- and Sirolimus-based Graft-versus-Host Disease Prophylaxis.

There is a paucity of data evaluating acute kidney injury (AKI) incidence and its relationship with the tacrolimus-sirolimus (Tac-Sir) concentrations in the setting of reduced-intensity conditioning (RIC) after allogeneic stem cell transplantation (allo-HSCT). This multicenter retrospective study evaluated risk factors of AKI defined by 2 classification systems, Kidney Disease Improving Global Outcome (KDIGO) score and "Grade 0-3 staging," in 186 consecutive RIC allo-HSCT recipients with Tac-Sir as graft-versus-host disease prophylaxis. Conditioning regimens consisted of fludarabine and busulfan (n = 53); melphalan (n = 83); or a combination of thiotepa, fludarabine, and busulfan (n = 50). A parametric model, with detailed Tac-Sir consecutive blood levels, describing time to AKI was developed using the NONMEM software version 7.4. Overall, 81 of 186 (44%) RIC allo-HSCT recipients developed AKI with a cumulative incidence of 42% at a median follow-up of 25 months. Time to AKI was best described using a piecewise function. AKI-predicting factors were melphalan-based conditioning regimen (HR, 1.96; P < .01), unrelated donor (HR, 1.79; P = .04), and tacrolimus concentration: The risk of AKI increased 2.3% per each 1-ng/mL increase in tacrolimus whole blood concentration (P < .01). In multivariate analysis, AKI grades 2 and 3 according to KDIGO staging were independent risk factors for 2-year nonrelapse mortality (HR, 2.8; P = .05; and HR, 6.6; P < .0001, respectively). According to the KDIGO score, overall survival decreased with the increase in severity of AKI: 78% for patients without AKI versus 68%, 50%, and 30% for grades 1, 2, and 3, respectively (P < .0001). In conclusion, AKI is frequent after Tac-Sir-based RIC allo-HSCT and has a negative impact on outcome. This study presents the first predictive model describing time to AKI as a function of tacrolimus drug concentration.

Impact of Undernutrition on the Pharmacokinetics and Pharmacodynamics of Anticancer Drugs: A Literature Review.

The etiology of undernourishment in cancer patients is multifactorial: tumor-related mechanisms (such as obstruction, metabolic abnormalities, and functionality changes) in addition to the influence of anticancer therapies, which can induce or worsen undernutrition. The evident role of undernutrition in cancer treatment outcomes suggests the need of considering nutritional status when evaluating anticancer drugs. In order to merge the available data and offer researchers and clinicians a global view of this phenomenon, the present manuscript reviews on a drug-by-drug basis the undernutrition-related pharmacokinetic and pharmacodynamic aspects of anticancer treatments. This review notes interesting trends in the relationship between undernourishment and pharmacokinetics across studies, and indicates that dosing modifications of these drugs may be necessary to optimize chemotherapeutic treatments. Furthermore, this review has compiled evidence regarding undernourishment's capacity of enhancing treatment-related myelosuppression, cardiotoxicity, ototoxicity, neurotoxicity, and malignancies.

Population pharmacokinetics of lenalidomide in multiple myeloma patients.

PURPOSE: Lenalidomide disease-specific toxicity profiles and potentially life-threatening adverse events support the consideration of diversity in starting doses. The aim of this study was to conduct a population pharmacokinetic analysis of lenalidomide in multiple myeloma patients to identify and evaluate non-studied covariates that could be used for dose individualization. METHODS: Blood samples were collected from 15 multiple myeloma patients. Nonlinear mixed-effects modeling was used to develop a population pharmacokinetic model and perform covariate analysis. The developed model was used to simulate dose schedules in order to explore the need of different dosing regimens in patients with different covariate values. RESULTS: The data were accurately described by a one-compartment model with first-order elimination. Absorption was best described using three transit compartments. Creatinine clearance and body surface area were identified as covariates affecting apparent clearance and apparent volume of distribution, respectively. Simulations revealed that lower starting doses than the standard 25 mg/daily could be used in patients with body surface area below 1.8 m2 and even higher doses might be necessary for patients with normal renal function and large body surface area. CONCLUSIONS: This study identified creatinine clearance and body surface area as covariates that have a clinically relevant impact on lenalidomide pharmacokinetics using population pharmacokinetics. In addition, the developed population pharmacokinetic model can be used to individualize lenalidomide dose in multiple myeloma patients, taking into account not only creatinine clearance but also body surface area.

Levofloxacin effect on erlotinib absorption. Evaluation of the interaction in undernutrition situations through population pharmacokinetic analysis in rats.

The main objective of this study was to develop a pharmacokinetic model in order to describe the intestinal absorption of erlotinib in rat and to quantify the interaction of levofloxacin on this process in well- and under-nourished rats. Absorption studies were performed in male Wistar rats. Concentration-time profiles in proximal and distal intestine were analysed through non-linear mixed effect modelling using the NONMEM software version 7.3. Simulations were performed in order to explore the influence of covariates on the apparent absorption rate constant. A passive absorption and an active secretion process best-described erlotinib absorption from lumen to enterocyte. The developed model indicates that levofloxacin exerts an inhibition on erlotinib efflux transporters of the gut epithelium. Undernourishment proved to significantly decrease the maximum capacity of the secretion process. Simulations evidenced that erlotinib absorption only takes place at high enough drug concentrations to overcome the effect of efflux transporters. On the other hand, when levofloxacin is present in the intestinal lumen of undernourished rats, erlotinib drug absorption takes place even at low erlotinib concentrations. In the clinical setting, this interaction may result in increased exposure to erlotinib, especially in undernourished cancer patients. Copyright © 2017 John Wiley & Sons, Ltd.

Effectiveness, toxicity, and economic evaluation of ipilimumab for the treatment of patients with metastatic melanoma in the Spanish outpatient setting.

To evaluate the effectiveness and toxicity profile of ipilimumab treatment and to examine the cost-effectiveness relation in a real-world sample of patients with metastasic melanoma. This was a multicenter, observational, retrospective cohorts study. To assess the effectiveness and safety of ipilimumab treatment progression-free survival (PFS), overall survival (OS) and adverse events were registered. An economic evaluation was performed and cost-effectiveness ratios (CERs) were calculated. Eleven patients were included, mean age 59 (SD=11) years. The median PFS was 3.83 months (95% confidence interval 0.98-9.80) and the median OS was 5.15 months (95% confidence interval 1.70-8.48). None of the patients included in the study achieved an objective response. A stable disease was achieved in four (36%) patients. The most commonly reported analytical adverse event was anemia, with all patients developing anemia in any grade. The most severe adverse event was neutropenia (n=6; 55%), with three patients developing grade 4 neutropenia (3/11; 27%). The total cost of ipilimumab treatment was &OV0556;483 397, with a median of 43 033 (interquartile range=9555) euros per patient. The median-based CER was 136 675 (28 539-474 865) euros per progression-free year gained and the median-based CER was 100 112 (23 107-374 893) euros per life-year gained. PFS observed in real-world patients was higher than that reported in clinical trials and OS was lower. The incidence of adverse events was higher. The additional cost per progression-free year gained was ∼&OV0556;136 675. The data from this study fill an important need for information on the relative value of this treatment in terms of cost-effectiveness.

A Wide Linearity Range Method for the Determination of Lenalidomide in Plasma by High-Performance Liquid Chromatography: Application to Pharmacokinetic Studies.

A wide linearity range analytical method for the determination of lenalidomide in patients with multiple myeloma for pharmacokinetic studies is required. Plasma samples were ultrasonicated for protein precipitation. A solid-phase extraction was performed. The eluted samples were evaporated to dryness under vacuum, and the solid obtained was diluted and injected into the high-performance liquid chromatography (HPLC) system. Separation of lenalidomide was performed on an Xterra RP C18 (250 mm length × 4.6 mm i.d., 5 µm) using a mobile phase consisting of phosphate buffer/acetonitrile (85:15, v/v, pH 3.2) at a flow rate of 0.5 mL · min-1 The samples were monitored at a wavelength of 311 nm. A linear relationship with good correlation coefficient (r = 0.997, n = 9) was found between the peak area and lenalidomide concentrations in the range of 100 to 950 ng · mL-1 The limits of detection and quantitation were 28 and 100 ng · mL-1, respectively. The intra- and interassay precisions were satisfactory, and the accuracy of the method was proved. In conclusion, the proposed method is suitable for the accurate quantification of lenalidomide in human plasma with a wide linear range, from 100 to 950 ng · mL-1 This is a valuable method for pharmacokinetic studies of lenalidomide in human subjects.

A model-based meta-analysis of sofosbuvir-based treatments in chronic hepatitis C patients.

The objective of this study was to compare the efficacy of sofosbuvir-based treatments in patients with chronic hepatitis C virus (HCV) infection using a model-based meta-analysis (MBMA). A bibliographic search was performed to identify clinical trials involving sofosbuvir as a unique direct-acting antiviral (DAA) agent or together with daclatasvir, ledipasvir or simeprevir for the treatment of diagnosed HCV infection. The time course of the virological response (VR) was modelled to estimate the effect of treatment and the influence of population characteristics on the longitudinal efficacy profile. The model was validated and simulations of 10 different treatment schedules were performed. Data from 19 clinical trials were included in the analysis. According to the developed model, therapy with sofosbuvir+ledipasvir is the most effective therapy in all scenarios, but it does not differ greatly in terms of sustained VR with respect to other combinations of DAA treatments. In conclusion, this MBMA generates knowledge regarding hypothetical head-to-head trials that have not been conducted previously. Therapies with sofosbuvir+ledipasvir are probably the most effective sofosbuvir-based treatments.

Effectiveness, toxicity, and economic evaluation of vinflunine for the treatment of patients with transitional cell carcinoma in the Spanish outpatient setting.

The aim of this study was to evaluate the effectiveness and toxicity profile of the vinflunine chemotherapy regimen and to examine the cost-effectiveness relation in a real-world sample of patients with transitional cell carcinoma of the bladder. This is a multicenter, observational, retrospective cohort study. To assess the effectiveness and safety of vinflunine treatment, progression-free survival, overall survival, and adverse events were registered. An economic evaluation was performed and cost-effectiveness ratios were calculated. A total of 37 patients were included in the study, with a mean age of 67 (SD=9) years. The median progression-free survival was 2.61 months (95% confidence interval 1.79-4.23) and the median overall survival was 5.72 months (95% confidence interval 3.34-10.35). An objective response was achieved in eight (22%) patients. Statistically significant differences were found between patients treated with vinflunine as a second-line therapy and those treated with vinflunine as a third-line therapy (P=0.036). The most commonly reported analytical adverse event was anemia (n=34; 92%), and the most severe was neutropenia (n=19; 51%), with nine patients developing grade 4 neutropenia (9/19; 47%). The total cost of vinflunine treatment was &OV0556;553 873, with a median of &OV0556;8524 (interquartile range, &OV0556;9220) per patient. The median-based cost-effectiveness ratio was &OV0556;44 789 (&OV0556;31 706-58 022) per progression-free year gained and &OV0556;22 750 (&OV0556;14 526-34 085) per life-year gained. The data from this study fill an important need for information on the relative value of this treatment in terms of cost-effectiveness and might help achieve an optimal quality healthcare system.

A pharmacokinetic approach to model-guided design of infliximab schedules in ulcerative colitis patients.

BACKGROUND: Infliximab, an anti-tumour necrosis factor approved for treatment of Crohn´s disease and ulcerative colitis, is administered at predefined interdose intervals. On insufficient response or loss of response, treatment can be intensified. The lack or loss of response is likely related to complex pharmacokinetics of infliximab. AIMS: To explore optimal dosing strategies of infliximab in treatment-naïve patients with ulcerative colitis through predictive Monte Carlo simulations based on a validated population PK model. METHODS: A population of 2,000 treatment-naïve patients was generated by Montecarlo simulation. Six dosing strategies for maintenance therapy were simulated on this population. Strategies 1 and 2 consisted on 5 mg/kg and 6 mg/kg doses, respectively, and 8 weeks inter-dose interval. Strategies 3 and 4 used Individualized doses, adjusted to albumin level, sex and body weight, and a fix interdose interval of 8 weeks to achieve a target trough concentration of 5 mg/L or 6 mg/L, respectively. Strategies 5 and 6 used a fix dose of 5 mg/kg and individualized inter-dose intervals, adjusted to the same covariates, to achieve a target concentration, of 5 mg/L or 6 mg/L, respectively. RESULTS: Strategies 2-6 reached trough levels statistically higher than strategy 1 (p < 0.05). Strategy 5 proved to be the best dosing strategy. It was associated with a higher proportion of responder patients than strategy 1 (62 % vs. 40 %) without reaching higher peak concentrations. CONCLUSIONS: Optimization of maintenance treatment of colitis with infliximab by a pharmacokinetic approach could benefit infliximab-naive patients with ulcerative colitis.

A pharmacokinetic approach to model-guided design of infliximab schedules in ulcerative colitis patients / Aproximación al diseño de un programa de administración de infliximab a pacientes con colitis ulcerosa basado en un modelo famacocinético

BACKGROUND: Infliximab, an anti-tumour necrosis factor approved for treatment of Crohn's disease and ulcerative colitis, is administered at predefined interdose-intervals. On insufficient response or loss of response, treatment can be intensified. The lack or loss of response is likely related to complex pharmacokinetics of infliximab. AIMS: To explore optimal dosing strategies of infliximab in treatment-naïve patients with ulcerative colitis through predictive Monte Carlo simulations based on a validated population PK model. METHODS: A population of 2,000 treatment-naïve patients was generated by Montecarlo simulation. Six dosing strategies for maintenance therapy were simulated on this population. Strategies 1 and 2 consisted on 5 mg/kg and 6 mg/kg doses, respectively, and 8 weeks inter-dose interval. Strategies 3 and 4 used Individualized doses, adjusted to albumin level, sex and body weight, and a fix interdose interval of 8 weeks to achieve a target trough concentration of 5 mg/L or 6 mg/L, respectively. Strategies 5 and 6 used a fix dose of 5 mg/kg and individualized inter-dose intervals, adjusted to the same covariates, to achieve a target concentration, of 5 mg/L or 6 mg/L, respectively. RESULTS: Strategies 2-6 reached trough levels statistically higher than strategy 1 (p < 0.05). Strategy 5 proved to be the best dosing strategy. It was associated with a higher proportion of responder patients than strategy 1 (62 % vs. 40 %) without reaching higher peak concentrations. CONCLUSIONS: Optimization of maintenance treatment of colitis with infliximab by a pharmacokinetic approach could benefit infliximab-naive patients with ulcerative colitis

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