The effects of a high-fat meal on single-dose vemurafenib pharmacokinetics

Predictability of human exposure by human-CYP3A4-transgenic mouse models: A meta-analysis

First-in-human dose predictions are primarily based on no-observed-adverse-effect levels in animal studies. Predictions from these animal models are only as effective as their ability to predict human results. To narrow the gap between human and animals, researchers have, among other things, focused on the replacement of animal cytochrome P450 (CYP) enzymes with their human counterparts (called humanization), especially in mice. Whereas research in humanized mice is extensive, the emphasis has been particularly on qualitative rather than quantitative predictions. Because the CYP3A4 enzyme is most involved in the metabolism of clinically used drugs, most benefit was expected from CYP3A4 models. There are several applications of these mouse models regarding in vivo CYP3A4 functionality, one of which might be their capacity to help improve first-in-human (FIH) dose predictions for CYP3A4-metabolized drugs. To evaluate whether human-CYP3A4-transgenic mouse models are better predictors of human exposure compared to the wild-type mouse model, we performed a meta-analysis comparing both mouse models in their ability to accurately predict human exposure of small-molecule drugs metabolized by CYP3A4. Results showed that, in general, the human-CYP3A4-transgenic mouse model had similar accuracy in the prediction of human exposure compared to the wild-type mouse model, suggesting that there is limited added value in humanization of the mouse Cyp3a enzymes if the primary aim is to acquire more accurate FIH dose predictions. Despite the results of this meta-analysis, corrections for interspecies differences through extension of human-CYP3A4-transgenic mouse models with pharmacokinetic modeling approaches seems a promising contribution to more accurate quantitative predictions of human pharmacokinetics.

Dynamic Changes in Gastrointestinal Fluid Characteristics after Food Ingestion Are Important for Quantitatively Predicting the In Vivo Performance of Oral Solid Dosage Forms in Humans in the Fed State

The aim of this study was to develop a simulation model to predict the in vivo performance of solid oral dosage forms in humans in the fed state. We focused on investigating the effect of dynamic changes in gastrointestinal (GI) fluid characteristics in the fed state on the in vivo performance of solid dosage forms. We used six solid dosage forms containing weak base drugs as model formulations, two with positive food effects in humans, two with negative food effects, and two which are not affected by food ingestion. These model drug formulations were used to perform biorelevant dissolution tests in the stomach and small intestine under both prandial states. The in vitro properties of the drug products obtained from these tests were then coupled with in silico models (fasted or fed) to predict food effects in humans. We successfully incorporated the dynamic changes in GI fluid characteristics and their effects on the in vivo dissolution of drugs into the prediction model for the fed state. This newly designed physiologically based biopharmaceutics modeling approach provided the precise and quantitative prediction of food effects (i.e., changes in C_max and AUC after food ingestion) in humans while considering the dynamic changes in fluid characteristics in the fed state.

Effect of Food on the Pharmacokinetics and Safety of a Novel c-Met Inhibitor SCC244: A Randomized Phase I Study in Healthy Subjects

Objective

This study aimed to investigate the effect of food on the pharmacokinetics and safety profiles of SCC244, a novel oral c-Met inhibitor in healthy Chinese male subjects.

Methods

It was a randomized, open-label, and 3-period crossover design, single-dose phase I clinical trial. A total of 18 healthy male subjects were enrolled. These subjects received a single oral 300 mg dose of SCC244 with a 14-day washout between each period. Blood samples were collected at the designated time points and determined using a validated liquid chromatography tandem mass spectrometry method. Pharmacokinetic parameters were calculated by noncompartmental methods. Tolerability was assessed by physical examination, vital sign measurements, 12-lead ECG, clinical laboratory tests, and adverse events (AEs) monitoring throughout the study.

Results

Eighteen eligible subjects were enrolled in the study. The ratios (90% CI) of C_max values for SCC244 in high-fat and low-fat meal states to that observed in fasted state were 194.8% (174.3-217.7%) and 194.6% (174.1-217.5%), respectively. The ratios of AUC_0-t and AUC_0-inf in the high-fat meal state versus the fasted state were 237.4% (208.7-270.0%) and 235.9% (207.5-268.3%), respectively. The ratios of AUC_0-t and AUC_0-inf in the low-fat meal state versus the fasted state were 219.2% (192.7-249.3%) and 218.3% (192.0-248.3%), respectively. Median T_max values and mean t_1/2 were similar in all groups. The most common AEs were headache, blood fibrinogen decreased, head discomfort, dizziness, and protein urine presence. All AEs were Common Terminology Criteria for Adverse Events (CTCAE) grade 1 (except 1 case of grade 2) and have resolved by the end of the study.

Conclusion

The bioavailability of the tablet formulation of SCC244 was significantly increased when administered with high- and low-fat meals. However, the meals did not affect the median T_max and t_1/2. Safety under different fed conditions was comparable to fasted conditions in this study.

Effects of food and race on the pharmacokinetics of lazertinib in healthy subjects and patients with EGFR mutation-positive advanced non-small cell lung cancer

OBJECTIVES

Lazertinib is a potent, irreversible, brain-penetrant, mutant-selective, and wild type-sparing third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor indicated for advanced non-small cell lung cancer (NSCLC). The study aimed to evaluate the effects of food and race on the pharmacokinetics (PK) of lazertinib from a healthy volunteer trial and PK data from NSCLC patients with EGFR mutation.

MATERIALS AND METHODS

An open-label, single-dose, two-period, single-sequence crossover study was conducted in healthy subjects with two race groups (non-Asian and Asian). Subjects orally received a single dose of lazertinib 240 mg in fasted and fed state (high-fat meal) in each period separated by a 21-day washout. An open-label, multicenter, phase 1/2 study was conducted in Asian and non-Asian patients with NSCLC. Patients were given oral lazertinib 20-320 mg once daily in fasted state continuously in 21-day cycles. PK parameters were evaluated using non-compartmental analysis.

RESULTS

A total of 24 healthy subjects (12 non-Asians and 12 Asians) and 52 NSCLC patients (22 non-Asians and 30 Asians) were evaluated. The change in the overall systemic exposure of lazertinib at fed state was less than 15%. Non-Asians showed 58-76% of the systemic exposure than Asians in healthy subjects. In contrast, there were no significant differences in systemic exposure by race both after single and multiple doses among NSCLC patients.

CONCLUSION

Lazertinib can be taken with or without food considering the comparable systemic exposures related to food. Although effect of race was not consistent across studies, there was no evidence for dose adjustment based on race.

Reducing Skin Toxicities from EGFR Inhibitors with Topical BRAF Inhibitor Therapy

Treatment of cancer with EGFR inhibitors is limited by on-target skin toxicities induced by inhibition of the MAPK pathway. BRAF inhibitors are known to paradoxically activate the MAPK downstream of EGFR, which we confirmed using human skin keratinocytes. We then conducted a phase I clinical trial testing the hypothesis that topical therapy with the BRAF inhibitor LUT014 could improve skin toxicities induced by EGFR inhibitors. Ten patients with metastatic colorectal cancer who had developed acneiform rash while being treated with cetuximab or panitumumab were enrolled in three cohorts. LUT014 was well tolerated, and there were no dose-limiting toxicities. The acneiform rash improved in the 6 patients who started with grade 2 rash in the low and intermediate cohorts. We conclude that topical LUT014 is safe and efficacious in improving rash from EGFR inhibitors, consistent with the mechanism of action inducting paradoxical MAPK activation. SIGNIFICANCE: BRAF inhibitor topical therapy could avoid dose reductions of EGFR inhibitors, locally treating the main dose-limiting skin toxicity of this class of agents.This article is highlighted in the In This Issue feature, p. 2113.

Therapeutic Drug Monitoring of Targeted Anticancer Protein Kinase Inhibitors in Routine Clinical Use: A Critical Review

BACKGROUND

Therapeutic response to oral targeted anticancer protein kinase inhibitors (PKIs) varies widely between patients, with insufficient efficacy of some of them and unacceptable adverse reactions of others. There are several possible causes for this heterogeneity, such as pharmacokinetic (PK) variability affecting blood concentrations, fluctuating medication adherence, and constitutional or acquired drug resistance of cancer cells. The appropriate management of oncology patients with PKI treatments thus requires concerted efforts to optimize the utilization of these drug agents, which have probably not yet revealed their full potential.

METHODS

An extensive literature review was performed on MEDLINE on the PK, pharmacodynamics, and therapeutic drug monitoring (TDM) of PKIs (up to April 2019).

RESULTS

This review provides the criteria for determining PKIs suitable candidates for TDM (eg, availability of analytical methods, observational PK studies, PK-pharmacodynamics relationship analysis, and randomized controlled studies). It reviews the major characteristics and limitations of PKIs, the expected benefits of TDM for cancer patients receiving them, and the prerequisites for the appropriate utilization of TDM. Finally, it discusses various important practical aspects and pitfalls of TDM for supporting better implementation in the field of cancer treatment.

CONCLUSIONS

Adaptation of PKIs dosage regimens at the individual patient level, through a rational TDM approach, could prevent oncology patients from being exposed to ineffective or unnecessarily toxic drug concentrations in the era of personalized medicine.

Chitosan caged liposomes for improving oral bioavailability of rivaroxaban: in vitro and in vivo evaluation

In this study, chitosan (CS) caged classic liposomes (CLs) and flexible liposomes (FLs) were developed to enhance the oral bioavailability of rivaroxaban (RVX) in the fasted condition. The prepared formulations were subjected to physicochemical characterization included: FTIR, DSC, zeta potential, particle size, polydispersity index, entrapment efficiency, in vitro dissolution, and transmission electron microscope imaging. The selected formulation (RVX-TFL2) composed of PL S100/Tween 80 (85/15% w/w) and coated with CS solution in the strength of (0.2% w/v) had a particle size of 105.67 nm, a zeta potential of +5.67 mV and EE of 96.07%. Compared to RXV suspension, the pharmacokinetic parameters (C _max, AUC_0-24, and AUC_0-∞) of RVX-TFL2 showed no statistically significant difference (P > 0.05) in the fasted and fed test animals. Besides, RVX bioavailability with RVX-TFL2 was improved by 59.66% and 26.97% in the fed and fasted states, respectively, compared to RVX suspension in the fed state. The result highlighted the efficacy of the prepared liquid formulation comprising CS coated liposomes in improving the oral bioavailability of RVX regardless of the fed state. Moreover, the studied liquid formulation could be utilized in developing a liquid dosage form that might be useful as a pediatric formulation of RVX.

Assessing OATP1B1- and OATP1B3-Mediated Drug-Drug Interaction Potential of Vemurafenib Using R-Value and Physiologically-Based Pharmacokinetic Models

Organic anion transporting polypeptides (OATP) 1B1 and OATP1B3 are important determinants of transporter-mediated drug-drug interactions (DDIs). Current studies assessed the OATP1B1 and OATP1B3-mediated DDI potential of vemurafenib, a kinase inhibitor drug with high protein binding and low aqueous solubility, using R-value and physiologically-based pharmacokinetic (PBPK) models. The total half-maximal inhibitory concentration (IC50,total) values of vemurafenib against OATP1B1 and OATP1B3 were determined in 100% human plasma in transporter-overexpressing human embryonic kidney 293 stable cell lines. The unbound fraction of vemurafenib in human plasma before (fu,plasma) and after addition into the uptake assay plate (fu,plasma,inc) were determined by rapid equilibrium dialysis. There was no statistically significant difference between fu,plasma and fu,plasma,inc. Vemurafenib IC50,total values against OATP1B1 and OATP1B3 are 175 ± 82 and 231 ± 26 μM, respectively. The R-values [R = 1 + fu,plasma × Iin,max/(fu,plasma,inc × IC50,total)] were then simplified as R = 1+Iin,max/IC50,total, and were 1.76 and 1.57 for OATP1B1 and OATP1B3, respectively. The simulated pravastatin AUC ratio was 1.28 when a single dose of pravastatin (40 mg) was co-administered with vemurafenib (960 mg, twice daily) at steady-state, compared to pravastatin alone. Both R-value and PBPK models predict that vemurafenib has the potential to cause OATP1B1- and OATP1B3-mediated DDIs.

An integrated computational methodology with data-driven machine learning, molecular modeling and PBPK modeling to accelerate solid dispersion formulation design

Drugs in solid dispersion (SD) take advantage of fast and extended dissolution, thus attains a higher bioavailability than the crystal form. However, current development of SD relies on a random large-scale formulation screening method with low efficiency. Current research aims to integrate various computational tools, including machine learning (ML), molecular dynamic (MD) simulation and physiologically based pharmacokinetic (PBPK) modeling, to accelerate the development of SD formulations. Firstly, based on a dataset consisting of 674 dissolution profiles of SD, the random forest algorithm was used to construct a classification model to distinguish two types of dissolution profiles: "spring-and-parachute" and "maintain supersaturation", and a regression model to predict the time-dependent dissolution profiles. Both of the two prediction models showed good prediction performance. Moreover, feature importance was performed to help understand the key information that contributes to the model. After that, the vemurafenib (VEM) SD formulation in previous report was used as an example to validate the models. MD simulation was used to investigate the dissolution behavior of two SD formulations with two polymers (HPMCAS and Eudragit) at the molecular level. The results showed that the HPMCAS-based formulation resulted in faster dissolution than the Eudragit formulation, which agreed with the reported experimental results. Finally, a PBPK model was constructed to accurately predict the human pharmacokinetic profile of the VEM-HPMCAS SD formulation. In conclusion, combined computational tools have been developed to in silico predict formulation composition, in vitro release and in vivo absorption behavior of SD formulations. The integrated computational methodology will significantly facilitate pharmaceutical formulation development than the traditional trial-and-error approach in the laboratory.

Clinical implications of food-drug interactions with small-molecule kinase inhibitors

During the past two decades, small-molecule kinase inhibitors have proven to be valuable in the treatment of solid and haematological tumours. However, because of their oral administration, the intrapatient and interpatient exposure to small-molecule kinase inhibitors (SMKIs) is highly variable and is affected by many factors, such as concomitant use of food and herbs. Food-drug interactions are capable of altering the systemic bioavailability and pharmacokinetics of these drugs. The most important mechanisms underlying food-drug interactions are gastrointestinal drug absorption and hepatic metabolism through cytochrome P450 isoenzymes. As food-drug interactions can lead to therapy failure or severe toxicity, knowledge of these interactions is essential. This Review provides a comprehensive overview of published studies involving food-drug interactions and herb-drug interactions for all registered SMKIs up to Oct 1, 2019. We critically discuss US Food and Drug Administration (FDA) and European Medicines Agency (EMA) guidelines concerning food-drug interactions and offer clear recommendations for their management in clinical practice.

Effect of Itraconazole, a Potent CYP3A4 Inhibitor, on the Steady-State Pharmacokinetics of Vemurafenib in Patients With BRAFV600 Mutation-Positive Malignancies

The effects of itraconazole, a strong CYP3A4 inhibitor, on the steady-state pharmacokinetics of vemurafenib were evaluated in a phase 1, multicenter, open-label, fixed-sequence study. Patients with BRAF^V600 mutation-positive metastatic malignancies received oral vemurafenib 960 mg twice daily on days 1 to 20 (period A) and oral vemurafenib 960 mg twice daily with oral itraconazole 200 mg once daily on days 21 to 40 (period B). A mixed-effects analysis of variance model was used to compare log-transformed area under the concentration-time curve during the dosing interval and maximum plasma concentration values for vemurafenib in 8 patients between period B (vemurafenib plus itraconazole) and period A (vemurafenib alone). Multiple doses of itraconazole increased steady-state exposure of vemurafenib by approximately 40%, with geometric least squares mean ratios (period B/period A) of 140% (90% confidence interval, 121-161) for both maximum plasma concentration and area under the concentration-time curve during the dosing interval. There was no apparent increase in incidence or severity of adverse events during coadministration of vemurafenib with itraconazole. In conclusion, coadministration of itraconazole with vemurafenib resulted in a modest increase in exposure of vemurafenib at steady state and was generally well tolerated.

Population Pharmacokinetics of Vemurafenib in Children With Recurrent/Refractory BRAF Gene V600E-Mutant Astrocytomas

Vemurafenib (Zelboraf) is an orally available BRAF^V600E inhibitor approved for the treatment of unresectable or metastatic BRAF^V600E -mutant melanoma. The primary objective of this work was to characterize the pharmacokinetics (PK) of vemurafenib in pediatric patients with recurrent/refractory astrocytomas harboring the BRAF^V600E mutation. The study was also designed to evaluate the feasibility of replacing whole vemurafenib tablets with crushed tablets in young children unable to swallow tablets. Twenty-five pediatric patients (median age, 8.8 years; range, 3.3-19.2) with recurrent/refractory BRAF^V600E -mutant astrocytomas received whole (n = 19) or crushed (n = 6) vemurafenib tablets twice daily. Plasma samples were collected on days 1, 15, and 22 in cycle 1 of vemurafenib treatment. Descriptive PK analyses demonstrated significant variability (approximately 6-fold) in drug exposure. A 1-compartment model with first-order absorption and elimination was developed by adjusting the vemurafenib PK model previously validated in adults with mutant BRAF^V600E melanoma. After inclusion of allometric scaling on total body weight, the model adequately described the PK of vemurafenib in children between a wide age range of 3 to 19 years old. In the crushed-tablet cohort, relative bioavailability was approximately 96% (95% confidence interval, 49%-142%) compared to that seen in pediatric patients receiving whole tablets based on the preliminary comparison analysis results. Moderate intrapatient variability (48%) of vemurafenib clearance was observed. There was significant correlation (R² = 0.83) between area under the plasma concentration-time curve and trough concentration at steady state. These results will help increase the number of pediatric patients for whom vemurafenib is accessible and facilitate improved dosing in pediatric patients with recurrent/refractory BRAF^V600E astrocytomas.

Effect of Vemurafenib on the Pharmacokinetics of a Single Dose of Tizanidine (a CYP1A2 Substrate) in Patients With BRAFV600 Mutation-Positive Malignancies

This phase 1 open-label, multicenter, 3-period, fixed-sequence study evaluated the effect of multiple doses of vemurafenib on the pharmacokinetics of 1 dose of tizanidine, a probe CYP1A2 substrate, in patients with BRAF^V600 mutation-positive metastatic malignancy. Patients received 1 dose of tizanidine 2 mg on day 1 (period A), vemurafenib 960 mg twice daily on days 2-21 (period B), and 1 dose of tizanidine 2 mg and vemurafenib 960 mg twice daily on day 22 (period C). Log-transformed area under the concentration-time curve (AUC) and maximum plasma concentration (C_max ) values for tizanidine in 16 patients were compared between periods A (tizanidine alone) and C (tizanidine plus vemurafenib) using an analysis of variance model. Multiple doses of vemurafenib increased plasma exposure of 1 dose of tizanidine, with geometric mean ratios (period C/period A) for C_max , AUC_inf , and AUC_last of 2.15 (90%CI, 1.71-2.71), 4.22 (90%CI, 3.37-5.28), and 4.74 (90%CI, 3.55-6.33), respectively; 90%CIs were all outside predefined limits for lack of drug-drug interaction (0.82-1.22). This study confirmed vemurafenib as a moderate inhibitor of CYP1A2 in vivo, with a statistically significant drug-drug interaction with tizanidine. Caution should be exercised when dosing vemurafenib concurrently with CYP1A2 substrates.

Evaluating the Role of Solubility in Oral Absorption of Poorly Water-Soluble Drugs Using Physiologically-Based Pharmacokinetic Modeling

Poor aqueous solubility and dissolution of drug candidates drive key decisions on lead series optimization during drug discovery, on formulation optimization, and clinical studies planning during drug development. The interpretation of the in vivo relevance of early pharmaceutical profiling is often confounded by the multiple factors affecting oral systemic exposure. There is growing evidence that in vitro drug solubility may underestimate the true in vivo solubility and lead to drug misclassification. Based on 10 poorly water‐soluble tyrosine kinase inhibitors, this paper demonstrates the use of physiologically‐based pharmacokinetic (PK) analysis in combination with early clinical PK data to identify drugs whose absorption is truly limited by solubility in vivo and, therefore, expected to exhibit food effect. Our study supports a totality of evidence approach using early clinical data to guide decisions on conducting drug interaction studies with food and acid‐reducing agents.

The Impact of Dose and Simultaneous Use of Acid-Reducing Agents on the Effectiveness of Vemurafenib in Metastatic BRAF V600 Mutated Melanoma: a Retrospective Cohort Study

BACKGROUND

The impact of dose and simultaneous use of acid-reducing agents (ARAs) on the effectiveness of vemurafenib is unknown.

OBJECTIVES

To determine the association between progression of metastatic BRAF V600 mutated melanoma and (1) dose reductions of vemurafenib and (2) simultaneous use of vemurafenib and ARAs.

PATIENT AND METHODS

A retrospective cohort study of 112 first-line vemurafenib users for melanoma was conducted (March 2012-March 2016), using electronic patient records and pharmacy dispensing records of a Dutch academic hospital. Cox regression analysis was used to estimate the risk of progression with full-dose (n = 64) versus reduced-dose vemurafenib (n = 48) and with simultaneous use of vemurafenib and ARAs (n = 35) versus vemurafenib alone (n = 77). Analyses were adjusted for age and sex.

RESULTS

In total, disease progression occurred in 55% of treated patients on vemurafenib, with a median progression-free survival of 6.0 (95% confidence interval [CI] 5.0-6.9) months. Compared to patients on vemurafenib alone, there was no increased risk of progression among patients requiring vemurafenib at a reduced dose or among patients receiving simultaneous therapy with vemurafenib and ARAs. In addition, there was no increased risk of progression among patients who used reduced-dose vemurafenib and ARAs versus those receiving full-dose vemurafenib as sole therapy. However, a tendency for progression was observed among patients who used full-dose vemurafenib and ARAs versus full-dose vemurafenib alone (adjusted hazard ratio [HRa] 2.37; 95% CI 0.97-5.76), which became statistically significant in a sensitivity analysis (HRa 4.56; 95% CI 1.51-13.75).

CONCLUSIONS

There was no association between the use of vemurafenib in a reduced dose or the simultaneous use of vemurafenib and ARAs and the risk of progression. In addition, there was no association between the simultaneous use of vemurafenib in a reduced dose and ARAs and the risk of progression. However, patients tolerating  full-dose vemurafenib simultaneously with ARAs might have an increased risk of progression. This finding requires prospective validation.

Enhancing the Oral Absorption of Kinase Inhibitors Using Lipophilic Salts and Lipid-Based Formulations

The absolute bioavailability of many small molecule kinase inhibitors (smKIs) is low. The reasons for low bioavailability are multifaceted and include constraints due to first pass metabolism and poor absorption. For smKIs where absorption limits oral bioavailability, low aqueous solubility and high lipophilicity, often in combination with high-dose requirements have been implicated in low and variable absorption, food-effects, and absorption-related drug-drug interactions. The current study has evaluated whether preparation of smKIs as lipophilic salts/ionic liquids in combination with coadministration with lipid-based formulations is able to enhance absorption for examples of this compound class. Lipophilic (docusate) salt forms of erlotinib, gefitinib, ceritinib, and cabozantinib (as example smKIs demonstrating low aqueous solubility and high lipophilicity) were prepared and isolated as workable powder solids. In each case, the lipophilic salt exhibited high and significantly enhanced solubility in lipidic excipients (>100 mg/g) when compared to the free base or commercial salt form. Isolation as the lipophilic salt facilitated smKI loading in model lipid-based formulations at high concentration, increased in vitro solubilization at gastric and intestinal pH and in some cases increased oral absorption (∼2-fold for cabozantinib formulations in rats). Application of a lipophilic salt approach can therefore facilitate the use of lipid-based formulations for examples of the smKI compound class where low solubility limits absorption and is a risk factor for increased variability due to food-effects.

Food for thought: formulating away the food effect - a PEARRL review

OBJECTIVES

Co-ingestion of oral dosage forms with meals can cause substantial changes in bioavailability relative to the fasted state. Food-mediated effects on bioavailability can have significant consequences in drug development, regulatory and clinical settings. To date, the primary focus of research has focused on the ability to mechanistically understand the causes and predict the occurrence of these effects.

KEY FINDINGS

The current review describes the mechanisms underpinning the occurrence of food effects, sheds new insights on the relative frequency for newly licensed medicines and describes the various methods by which they can be overcome. Analysis of oral medicines licensed by either the EMA or FDA since 2010 revealed that over 40% display significant food effects. Due to altered bioavailability, these medicines are often required to be dosed, rather restrictively, in either the fed or the fasted state, which can hinder clinical usefulness.

SUMMARY

There are clinical and commercial advantages to predicting the presence of food effects early in the drug development process, in order to mitigate this risk of variable food effect bioavailability. Formulation approaches aimed at reducing variable food-dependent bioavailability, through the use of bio-enabling formulations, are an essential tool in addressing this challenge and the latest state of the art in this field are summarised here.

Preparation and Optimization of Rivaroxaban by Self-Nanoemulsifying Drug Delivery System (SNEDDS) for Enhanced Oral Bioavailability and No Food Effect

In this paper, a novel self-nanoemulsifying drug delivery system (SNEDDS) was used to improve the oral bioavailability in fasted state and diminish the food effect for rivaroxaban. Oil, surfactant, and co-surfactant were selected by saturated solubility study. IPM, Tween80, and 1,2-propanediol were finally selected as oil, surfactant, and co-surfactant, respectively. The pseudo-ternary-phase diagram was utilized to optimize the preliminary composition of SNEDDS formulation. The optimized rivaroxaban-SNEDDS formulation was selected by central composite design (CCD) of response surface methodology. Optimized SNEDDS formulation was evaluated for drug content, self-emulsifying time, droplet size, zeta potential, polydispersity index, Fourier transform-infrared (FTIR) spectroscopy, and transmission electron microscope (TEM). The drug dissolution profile compared to the commercial formulation Xarelto® (20 mg rivaroxaban) was determined in four different media (pH 1.2HCl, pH 4.5NaAc-HAc, pH 6.8PBS, and water). The result indicated that the SNEDDS formulation had successfully increased the drug solubility in four different media. A HPLC-MS method that indicated a high sensitivity, strong attribute, and high accuracy characteristic was built to measure the drug concentration in plasma. The fast/fed in vivo pharmacokinetics studies of SNEDDS formulation and Xarelto® were carried out in adult beagle dog, rivaroxaban with no food effect was achieved in SNEDDS formulation compared with Xarelto® in fed state. The result suggested that SNEDDS formulation in this study is useful to increase the oral bioavailability and diminish the food effect in fasted state.

Effect of food and acid-reducing agents on the absorption of oral targeted therapies in solid tumors

Oral targeted therapies represent an increasingly important group of drugs within modern oncology. With the shift from intravenously to orally administered drugs, drug absorption is a newly introduced factor in drug disposition. The process of absorption can have a large effect on inter- and intrasubject variability in drug exposure and thereby potentially treatment benefit or the severity of toxicities. The intake of oral targeted therapies with food and concomitant use of acid-reducing agents (ARAs) can significantly affect drug absorption. The size and direction of the effect of food and ARAs on drug absorption varies among drugs as a result of different chemical characteristics. Therefore, an awareness and understanding of these effects for each drug is essential to optimize patient outcomes.

Plasma vemurafenib concentrations in advanced BRAFV600mut melanoma patients: impact on tumour response and tolerance

BACKGROUND

Vemurafenib improves survival in advanced BRAFV600(mut) melanoma patients, but tolerance is often poor and resistance frequently occurs, without predictive factor. Our aim was to investigate for the first time a relationship between plasma vemurafenib concentration (PVC) and efficacy or tolerance.

METHODS

Plasma samples from unresectable metastatic BRAFV600(mut) melanoma patients treated with vemurafenib monotherapy were prospectively collected at each tumour response evaluation (RECIST 1.1) or when adverse event occurred (CTCAE 4.0). PVC was measured with liquid chromatography-tandem mass spectrometry. Herein, we report on PVC at steady state (≥14 days after vemurafenib introduction or dose modification). Samples collected after first melanoma progression were excluded from the response analysis. All samples were analysed in the tolerance analysis. We kept the closest collected sample from the onset of each adverse effect or the one with the highest PVC in the absence of this adverse effect. Comparisons of means (Student's t-tests and Wilcoxon rank sum tests) and of frequencies (χ(2) tests) were carried out. A logistic regression analysis identified predictors of progression.

RESULTS

We included 105 plasma samples in 23 patients (10M/13F). Initial vemurafenib dose was 960 mg b.i.d., reduced by 25% (8 patients) or 50% (2 patients) for intolerance in 10 patients (44%). PVC displayed high inter-individual variability (13.0-109.8 µg/ml, median 54.0). Mean PVC was lower at time of first progression (38.8 ± 19.7 µg/ml) than mean PVC found when tumour was stable or in partial or complete response (56.4 ± 21.0 µg/ml, P = 0.013, 21 patients). Logistic regression revealed that having a low PVC (P = 0.01) or brain metastasis (P = 0.01) were both significantly and independently associated with tumour progression. High PVC was not statistically significantly associated with the occurrence of adverse effects.

CONCLUSION

PVC at steady state is highly variable and low PVC was associated with tumour progression, suggesting a new path to melanoma resistance to vemurafenib.

Variability in bioavailability of small molecular tyrosine kinase inhibitors

Small molecular tyrosine kinase inhibitors (smTKIs) are in the centre of the very quickly expanding area of personalized chemotherapy and oral applicability thereof. The number of drugs in this class is rapidly growing, with twenty current approvals by both the European Medicines Agency (EMA) and the Food and Drug Administration (FDA). The drugs are, however, generally characterized by a poor oral, and thus variable, bioavailability. This results in significant variation in plasma levels and exposure. The cause is a complex interplay of factors, including poor aqueous solubility, issued permeability, membrane transport and enzymatic metabolism. Additionally, food and drug-drug interactions can play a significant role. The issues related with an impaired bioavailability generally receive little attention. To the best of our knowledge, this article is the first to provide an overview of the factors that determine the bioavailability of the smTKIs.

Homologous Mutation to Human BRAF V600E Is Common in Naturally Occurring Canine Bladder Cancer--Evidence for a Relevant Model System and Urine-Based Diagnostic Test

Targeted cancer therapies offer great clinical promise, but treatment resistance is common, and basic research aimed at overcoming this challenge is limited by reduced genomic and biologic complexity in artificially induced rodent tumors compared with their human counterparts. Animal models that more faithfully recapitulate genotype-specific human pathology could improve the predictive value of these investigations. Here, a newly identified animal model for oncogenic BRAF-driven cancers is described. With 20,000 new cases in the United States each year, canine invasive transitional cell carcinoma of the bladder (InvTCC) is a common, naturally occurring malignancy that shares significant histologic, biologic, and clinical phenotypes with human muscle invasive bladder cancer. In order to identify somatic drivers of canine InvTCC, the complete transcriptome for multiple tumors was determined by RNAseq. All tumors harbored a somatic mutation that is homologous to the human BRAF(V600E) mutation, and an identical mutation was present in 87% of 62 additional canine InvTCC tumors. The mutation was also detectable in the urine sediments of all dogs tested with mutation-positive tumors. Functional experiments suggest that, like human tumors, canine activating BRAF mutations potently stimulate the MAPK pathway. Cell lines with the mutation have elevated levels of phosphorylated MEK, compared with a line with wild-type BRAF. This effect can be diminished through application of the BRAF(V600E) inhibitor vemurafenib. These findings set the stage for canine InvTCC as a powerful system to evaluate BRAF-targeted therapies, as well as therapies designed to overcome resistance, which could enhance treatment of both human and canine cancers

IMPLICATIONS

This study demonstrates the activating BRAF mutation (V600E), which is found in multiple human cancers, is a driver of canine InvTCC, and highlights a urine-based test for quick diagnosis.

A single-dose mass balance and metabolite-profiling study of vemurafenib in patients with metastatic melanoma

Vemurafenib, a selective inhibitor of oncogenic BRAF kinase carrying the V600 mutation, is approved for treatment of advanced BRAF mutation–positive melanoma. This study characterized mass balance, metabolism, rates/routes of elimination, and disposition of ¹⁴C-labeled vemurafenib in patients with metastatic melanoma. Seven patients with metastatic BRAF-mutated melanoma received unlabeled vemurafenib 960 mg twice daily for 14 days. On the morning of day 15, patients received ¹⁴C-labeled vemurafenib 960 mg (maximum 2.56 MBq [69.2 μCi]). Thereafter, patients resumed unlabeled vemurafenib (960 mg twice daily). Blood, urine, and feces were collected for metabolism, pharmacokinetic, and dose recovery analysis. Within 18 days after dose, ∼95% of ¹⁴C-vemurafenib–related material was recovered from feces (94.1%) and urine (<1%). The parent compound was the predominant component (95%) in plasma. The mean plasma elimination half-life of ¹⁴C-vemurafenib–related material was 71.1 h. Each metabolite accounted for <0.5% and ≤6% of the total administered dose in urine and feces, respectively (0–96 h postdose). No new metabolites were detected. Vemurafenib was well-tolerated. Excretion of vemurafenib via bile into feces is considered the predominant elimination route from plasma with minor renal elimination (<1%).

Vemurafenib: an evidence-based review of its clinical utility in the treatment of metastatic melanoma

The discovery of BRAF mutations in the majority of patients with metastatic melanoma combined with the identification of highly selective BRAF inhibitors have revolutionized the treatment of patients with metastatic melanoma. The first highly specific BRAF inhibitor, vemurafenib, began clinical testing in 2008 and moved towards a rapid approval in 2011. Vemurafenib induced responses in ~50% of patients with metastatic BRAF-mutant melanoma and demonstrated improved overall survival in a randomized Phase III trial. Furthermore, vemurafenib is well-tolerated with a low toxicity profile and rapid onset of action. Finally, vemurafenib is active even in patients with widely metastatic disease. Despite the success of vemurafenib in treating patients with BRAF-mutant metastatic melanoma, most, if not all, patients ultimately develop resistance resulting in disease progression at a median time of ~6 months. Multiple mechanisms of resistance have been described and rationale strategies are underway to combat resistance. This review highlights the development, clinical utility, resistance mechanisms, and future use of vemurafenib both in melanoma and other malignancies. We consulted PubMed, Scopus, MEDLINE, ASCO annual symposium abstracts, and http://clinicaltrials.gov/ for the purpose of this review.