Therapeutic drug monitoring in anticancer agents: perspectives of Australian medical oncologists.

BACKGROUND: In the development of anticancer agents for solid tumours, body surface area continues to be used to personalise dosing despite minimal evidence for its use over other dosing strategies. With the development of tyrosine kinase inhibitors and other oral targeted anticancer agents, dosing using therapeutic drug monitoring (TDM) is now utilised in many health systems but has had limited uptake in Australia. AIM: To determine attitudes and barriers to the implementation of TDM among Australian oncologists. METHODS: A comprehensive questionnaire was developed by the Dutch Pharmacology Oncology Group from semistructured interviews of stakeholders. Seventy-nine questions across seven domains were developed with three free-text responses. This was rationalised to 17 questions with three free-text responses for Australian medical oncologists who identified limited experience with TDM. RESULTS: Fifty-seven responses were received, with 49 clinicians (86%) identifying limited experience of performing TDM in daily practice. Clinicians were positive (62-91% agree/strongly agree across seven questions) about the advantages of TDM. There was a mixed response for cost-effectiveness and scientific evidence being a barrier to implementation, but strong agreement that prospective studies were needed (75% agreed or strongly agreed); that national treatment guidelines would enable practice (80%) and that a 'pharmacology of oncolytics' education programme would be useful (96%) to provide knowledge for dose individualisation. CONCLUSION: Despite the limited experience of TDM in oncology in Australia, medical oncologists appear positive about the potential benefit to their patients. We have identified three barriers to implementation that could be targeted for increased adoption of TDM in oncology in Australia.

Phenotype versus genotype to optimize cancer dosing in the clinical setting-focus on 5-fluorouracil and tyrosine kinase inhibitors.

Cancer medicines often have narrow therapeutic windows; toxicity can be severe and sometimes fatal, but inadequate dose intensity reduces efficacy and survival. Determining the optimal dose for each patient is difficult, with body-surface area used most commonly for chemotherapy and flat dosing for tyrosine kinase inhibitors, despite accumulating evidence of a wide range of exposures in individual patients with many receiving a suboptimal dose with these strategies. Therapeutic drug monitoring (measuring the drug concentration in a biological fluid, usually plasma) (TDM) is an accepted and well validated method to guide dose adjustments for individual patients to improve this. However, implementing TDM in routine care has been difficult outside a research context. The development of genotyping of various proteins involved in drug elimination and activity has gained prominence, with several but not all Guideline groups recommending dose reductions for particular variant genotypes. However, there is increasing concern that dosing recommendations are based on limited data sets and may lead to unnecessary underdosing and increased cancer mortality. This Review discusses the evidence surrounding genotyping and TDM to guide decisions around best practice.

Economic evaluation of personalized vs. standard dosing of 5-fluorouracil in first-line chemotherapy for metastatic colorectal cancer in Australia.

AIMS: Using pharmacokinetics (PK)-guided 5-fluorouracil (5-FU) for metastatic colorectal cancer (mCRC) improves overall survival (OS) and decreases toxicity, yet its value for money in the Australian setting is unknown. Our study assesses the cost-effectiveness of PK vs. body surface area (BSA) dosing of 5-FU for patients with mCRC. METHODS: We developed a semi-Markov model with four health states to compare PK-guided dosing within a FOLFOX regimen vs. BSA-guided dosing for mCRC patients from an Australian healthcare system perspective. Transition probabilities were derived from fitted survival models, with utility values obtained directly from published studies. We calculated direct healthcare costs, quality-adjusted life years (QALYs) and incremental cost-effectiveness ratios (ICERs), and included both one-way and probabilistic sensitivity analyses. RESULTS: BSA-guided FOLFOX provided 1.291 QALYs at a cost of $36 379, compared with PK-guided FOLFOX which delivered 1.751 QALYs at a cost of $32 564. Therefore, PK-guided dosing emerges as the dominant strategy offering both better health outcomes and lower costs. The variables that had the greatest impact on the overall ICER were the adverse event rates in the BSA and PK groups, model time horizon, utility of progression-free survival and PREDICT assay cost. Our univariate and multivariate sensitivity analysis confirmed that the ICER for PK FOLFOX consistently remained below $50 000 per QALY across all tested variables. CONCLUSIONS: PK dose management of 5-FU-based chemotherapy in mCRC patients appears to be a cost-saving strategy in Australia. However, our model estimates are drawn from limited, low-quality evidence. Further evidence from randomized controlled trials (RCTs), directly comparing PK-based to BSA-based dosing across a variety of current regimens, is needed to address our model's uncertainties.

Comparison of capecitabine concentrations determined by microsampling versus plasma concentrations for therapeutic drug monitoring: a pilot study.

OBJECTIVES: Therapeutic drug monitoring allows personalized dosing of chemotherapy, but is not well established for capecitabine. The aim of this study was to compare the concentrations of capecitabine and its metabolites obtained simultaneously by microsampling with plasma sampling and their acceptability to patients. METHODS: Adults taking capecitabine for cancer had paired (duplicate) microsampling at steady state (hour 2 post dose) using Mitra® devices and venous blood samples for analysis. Capecitabine and metabolites were measured using a validated mass spectrometry assay. Correlation between the sampling methods was determined. Patients' preferences were elicited using a Likert numeric rating scale and pain by a Visual Analog Scale (range, 0-10). KEY FINDINGS: Capecitabine concentrations from 10 patients (60 paired samples) by microsampling and plasma sampling were highly correlated (Pearson correlation: 0.97, Coefficients of determination: 0.94, P < 0.0001). Capecitabine concentrations in capillary sampling were consistently lower than the paired plasma concentration (median capecitabine capillary/plasma concentration ratio = 2851/3846 µg/l 75%). The agreement between sampling matrices showed a 28% bias (95% Cl, 4.02-52.00). Participant ratings showed microsampling was the preferred method by all 10 patients. Most participants reported no pain with microsampling (median 0, range 0-1). CONCLUSION: Capecitabine concentration measured by microsampling and plasma sampling were highly correlated, but consistently lower in microsampling. Microsampling was the preferred method with minimal pain.

Fluoropolymer Functionalization of Organ-on-Chip Platform Increases Detection Sensitivity for Cannabinoids.

Microfluidic technology is applied across various research areas including organ-on-chip (OOC) systems. The main material used for microfluidics is polydimethylsiloxane (PDMS), a silicone elastomer material that is biocompatible, transparent, and easy to use for OOC systems with well-defined microstructures. However, PDMS-based OOC systems can absorb hydrophobic and small molecules, making it difficult and erroneous to make quantitative analytical assessments for such compounds. In this paper, we explore the use of a synthetic fluoropolymer, poly(4,5-difluoro-2,2-bis(trifluoromethyl)-1,3-dioxole-co-tetrafluoroethylene) (Teflon™ AF 2400), with excellent "non-stick" properties to functionalize OOC systems. Cannabinoids, including cannabidiol (CBD), are classes of hydrophobic compounds with a great potential for the treatment of anxiety, depression, pain, and cancer. By using CBD as a testing compound, we examined and systematically quantified CBD absorption into PDMS by means of an LC-MS/MS analysis. In comparison to the unmodified PDMS microchannels, an increase of approximately 30× in the CBD signal was detected with the fluoropolymer surface modification after 3 h of static incubation. Under perfusion conditions, we observed an increase of nearly 15× in the CBD signals from the surface-modified microchannels than from the unmodified microchannels. Furthermore, we also demonstrated that fluoropolymer-modified microchannels are compatible for culturing hCMEC/D3 endothelial cells and for CBD perfusion experiments.

Daily Cannabidiol Administration for 10 Weeks Modulates Hippocampal and Amygdalar Resting-State Functional Connectivity in Cannabis Users: A Functional Magnetic Resonance Imaging Open-Label Clinical Trial.

Introduction: Cannabis use is associated with brain functional changes in regions implicated in prominent neuroscientific theories of addiction. Emerging evidence suggests that cannabidiol (CBD) is neuroprotective and may reverse structural brain changes associated with prolonged heavy cannabis use. In this study, we examine how an ∼10-week exposure of CBD in cannabis users affected resting-state functional connectivity in brain regions functionally altered by cannabis use. Materials and Methods: Eighteen people who use cannabis took part in a ∼10 weeks open-label pragmatic trial of self-administered daily 200 mg CBD in capsules. They were not required to change their cannabis exposure patterns. Participants were assessed at baseline and post-CBD exposure with structural magnetic resonance imaging (MRI) and a functional MRI resting-state task (eyes closed). Seed-based connectivity analyses were run to examine changes in the functional connectivity of a priori regions-the hippocampus and the amygdala. We explored if connectivity changes were associated with cannabinoid exposure (i.e., cumulative cannabis dosage over trial, and plasma CBD concentrations and Δ9-tetrahydrocannabinol (THC) plasma metabolites postexposure), and mental health (i.e., severity of anxiety, depression, and positive psychotic symptom scores), accounting for cigarette exposure in the past month, alcohol standard drinks in the past month and cumulative CBD dose during the trial. Results: Functional connectivity significantly decreased pre-to-post the CBD trial between the anterior hippocampus and precentral gyrus, with a strong effect size (d=1.73). Functional connectivity increased between the amygdala and the lingual gyrus pre-to-post the CBD trial, with a strong effect size (d=1.19). There were no correlations with cannabinoids or mental health symptom scores. Discussion: Prolonged CBD exposure may restore/reduce functional connectivity differences reported in cannabis users. These new findings warrant replication in a larger sample, using robust methodologies-double-blind and placebo-controlled-and in the most vulnerable people who use cannabis, including those with more severe forms of Cannabis Use Disorder and experiencing worse mental health outcomes (e.g., psychosis, depression).

Influence of age on pharmacokinetics of capecitabine and its metabolites in older adults with cancer: a pilot study.

BACKGROUND: Capecitabine is an oral chemotherapy prodrug of 5-fluorouracil (5-FU) with unpredictable toxicity, especially in older adults. The aim of this study was to evaluate the pharmacokinetics (PK) of capecitabine and its metabolites in younger adults (< 70 years) and older adults (≥ 70 years) receiving capecitabine for solid cancer. METHODS: Eligible participants receiving capecitabine had 2 venous samples collected on day 14 of cycle 1 and cycle 2 of their treatment. Capecitabine and metabolite concentrations were determined using liquid chromatography with tandem mass spectrometry. A Bayesian estimation approach was used to generate individual estimates of PK parameters for 5-FU. A linear mixed-effect analysis of variance (ANOVA) model was used to compare dose-normalised log-transformed PK parameters between age groups. Correlations were determined by linear regression and logistic regression analyses. RESULTS: Of the total 26 participants, 58% were male with a median age of 67 years (range, 37-85) with 54% aged < 70 years and 46% aged ≥ 70 years. Participants aged ≥ 70 years, compared to those aged < 70 years, had a greater 5-FU exposure based on area under the concentration-time curve (AUC) of 17% (90% CI 103-134%; 0.893 vs. 0.762 mg h/L) and 14% increase in maximal concentration, Cmax (90% CI 82.1-159%; 0.343 vs. 0.300 mg/L). The 5-FU Cmax was positively associated with time up and go (TUG) (Pearson's correlation 0.77, p = 0.01), but not other geriatric assessment domains or severe toxicity. CONCLUSION: 5-FU exposure was significantly increased in older adults compared to younger adults receiving equivalent doses of capecitabine, and is a possible cause for increased toxicity in older adults.

Dried Blood Spot Sampling in the Monitoring of Anticancer Therapy for Solid Tumors: A Systematic Review.

BACKGROUND: Dried blood spot (DBS) sampling is a convenient alternative to whole-blood sampling for therapeutic drug monitoring (TDM) in clinical practice. The aim of this study was to systematically review studies that have examined and used DBS sampling for the TDM of chemotherapy and targeted therapy agents for the treatment of patients with solid cancers. METHODS: Using the PRISMA guidelines, a systematic literature search of EMBASE and PUBMED was performed to identify eligible clinical studies that used DBS sampling to monitor chemotherapy or targeted therapy for the treatment of solid cancers. RESULTS: Of the 23 eligible studies, 3 measured concordance between drug concentrations determined by DBS and whole-blood, 7 developed analytical methods of DBS, and 13 performed both. DBS was employed for the TDM of everolimus (3 studies), vemurafenib (2 studies), pazopanib (2 studies), abiraterone (2 studies), mitotane, imatinib, adavosertib, capecitabine, 5-fluorouracil, gemcitabine, cyclophosphamide, ifosfamide, etoposide, irinotecan, docetaxel, gefitinib, palbociclib/ribociclib, and paclitaxel (one study each). The studies included a median of 14 participants (range: 6-34), with 10-50 µL of blood dispensed on DBS cards (20) and Mitra devices (3). Seventeen of the 20 studies that used DBS found no significant impact of the hematocrit on the accuracy and precision of the developed method in the normal hematocrit ranges (eg, 29.0%-59.0%). DBS and plasma or venous concentrations were highly correlated (correlation coefficient, 0.872-0.999) for all drugs, except mitotane, which did not meet a predefined level of significance (r > 0.872; correlation coefficient, r = 0.87, P < 0.0001). CONCLUSIONS: DBS provides an alternative sampling strategy for the TDM of many anticancer drugs. Further research is required to establish a standardized approach for sampling and processing DBS samples to allow future implementation.

A phase 1 clinical trial of the repurposable acetyllysine mimetic, n-methyl-2-pyrrolidone (NMP), in relapsed or refractory multiple myeloma.

BACKGROUND: N-methyl-2-pyrrolidone (NMP) is an epigenetically active chemical fragment and organic solvent with numerous applications including use as a drug-delivery vehicle. Previously considered biologically inert, NMP demonstrates immunomodulatory and anti-myeloma properties that are partly explained by acetyllysine mimetic properties and non-specific bromodomain inhibition. We therefore evaluated orally administered NMP in a phase 1 dose-escalation trial to establish its maximum tolerated dose (MTD) in patients with relapsed/refractory multiple myeloma (RR-MM). Secondary endpoints were safety, pharmacokinetics (PK), overall response rate and immunological biomarkers of activity. RESULTS: Thirteen patients received NMP at starting doses between 50 and 400 mg daily. Intra-patient dose escalation occurred in five patients, with one attaining the ceiling protocolised dose of 1 g daily. Median number of monthly cycles commenced was three (range 1-20). Grade 3-4 adverse events (AEs) were reported in seven (54%; 95% CI 25-81%) patients. Most common AEs (> 30% of patients) of any grade were nausea and musculoskeletal pain. The only dose limiting toxicity (DLT) was diarrhoea in a patient receiving 200 mg NMP (overall DLT rate 8%; 95% CI 0-36%). Hence, the MTD was not defined. Median progression-free and overall survival were 57 (range 29-539) days and 33 (95% CI 9.7- > 44) months, respectively. The best response of stable disease (SD) was achieved in nine patients (69%; 95% CI 39-91%). PK analysis demonstrated proportional dose-concentrations up to 400 mg daily, with a more linear relationship above 500 mg. Maximum plasma concentrations (Cmax) of 16.7 mg/L at the 800 mg dose were below those predicted to inhibit BET-bromodomains. Peripheral blood immune-profiling demonstrated maintenance of natural killer (NK) cells, and a gene expression signature suggestive of enhanced T, B and NK cell functions; a subject with prolonged exposure manifested sustained recovery of B and NK cells at 12 months. CONCLUSIONS: NMP demonstrated potential disease stabilising and immunomodulatory activity at sub-BET inhibitory plasma concentrations and was well tolerated in RR-MM; an MTD was not determined up to a maximum dose of 1 g daily. Further dose-finding studies are required to optimise NMP dosing strategies for therapeutic intervention.

Paclitaxel and Therapeutic Drug Monitoring with Microsampling in Clinical Practice.

Paclitaxel is an anticancer agent efficacious in various tumors. There is large interindividual variability in drug plasma concentrations resulting in a wide variability in observed toxicity in patients. Studies have shown the time the concentration of paclitaxel exceeds 0.05 µM is a predictive parameter of toxicity, making dose individualization potentially useful in reducing the adverse effects. To determine paclitaxel drug concentration, a venous blood sample collected 24 h following the end of infusion is required, often inconvenient for patients. Alternatively, using a microsampling device for self-sampling would facilitate paclitaxel monitoring regardless of the patient's location. We investigated the feasibility of collecting venous and capillary samples (using a Mitra® device) from cancer patients to determine the paclitaxel concentrations. The relationship between the venous plasma and whole blood and venous and capillary blood (on Mitra®) paclitaxel concentrations, defined by a Passing-Bablok regression, were 0.8433 and 0.8569, respectively. Demonstrating a clinically acceptable relationship between plasma and whole blood paclitaxel concentration would reduce the need to establish new target concentrations in whole blood. However, in this study, comparison of venous and capillary blood using Mitra® for sampling displayed wide confidence intervals suggesting the results from the plasma and whole blood on this device may not be interchangeable.

LC-MS/MS method for simultaneous quantification of ten antibiotics in human plasma for routine therapeutic drug monitoring.

Background: Optimizing antimicrobial therapy to attain drug exposure that limits the emergence of resistance, effectively treats the infection, and reduces the risk of side effects is of a particular importance in critically ill patients, in whom normal functions are augmented or/and are infected with pathogens less sensitive to treatment. Achievement of these goals can be enhanced by therapeutic drug monitoring (TDM) for many antibiotics. A liquid chromatography tandem mass spectrometry (LC-MS/MS) method is presented here for simultaneous quantification of ten antimicrobials: cefazolin (CZO), cefepime (CEP), cefotaxime (CTA), ceftazidime (CTZ), ciprofloxacin (CIP), flucloxacillin (FLU), linezolid (LIN), meropenem (MER), piperacillin (PIP) and tazobactam (TAZ) in human plasma. Methods: Plasma samples were precipitated with acetonitrile and injected into the LC-MS/MS. Chromatographic separation was on a Waters Acquity BEH C18 column. Compounds were eluted with water and acetonitrile containing 0.1 % formic acid, using a gradient (0.5-65 % B), in 3.8 min. The flow rate was 0.4 mL/min, and the run time was 5.8 min. Results: The calibration curves were linear across the tested concentration ranges (0.5-250, CZO, CEP, CTA, CTZ and FLU; 0.2-100, MER and TAZ; 0.1-50, CIP and LIN and 1-500 mg/L, PIP). The intra and inter-day imprecision was < 11 %. Accuracy ranged from 95 to 114 %. CTZ and MER showed ionization suppression while CIP showed ionization enhancement, which was normalized with the use of the internal standard. Conclusion: An LC-MS/MS method for simultaneous quantification of ten antimicrobials in human plasma was developed for routine TDM.

Mitigating analyte to stable isotope labelled internal standard cross-signal contribution in quantitative liquid chromatography-tandem mass spectrometry.

Background: Utilising stable isotope labelled internal standards (SIL-IS) in quantitative LC-MS/MS drug analysis is the most widely used approach to normalise for variability during sample quantification processes. However, compounds containing atoms such as Sulphur, Chlorine or Bromine, could potentially cause cross-signal contribution to the SIL-IS from the naturally occurring isotopes, resulting in non-linear calibration curves. A simple, novel method of mitigating the effect is presented here. It entails monitoring of a less abundant SIL-IS isotope, as the precursor ion, of a mass that has no/minimal isotopic contribution from the analyte isotopes. Methods: Experiments were conducted on two LC-MS/MS analysers: Waters Xevo TQ-S and Shimadzu 8050. Flucloxacillin (FLX) was used as an example. Two transitions were selected for FLX (m/z 454 â†’ 160 â†’ 295) and one for each of the SIL-IS isotopes (m/z 458 â†’ 160 for the isotope 457 g/mol and m/z 460 â†’ 160 for the isotope 459 g/mol). Assay biases were assessed at three SIL-IS concentrations: 0.7, 7 and 14 mg/L for each isotope. Results: When using the SIL-IS isotope m/z 458 â†’ 160 at a concentration of 0.7 mg/L, biases were up to 36.9 % on both instruments. Increasing the SIL-IS concentration to 14 mg/L, reduced the bias to 5.8 %. Using the less abundant isotope, m/z 460 â†’ 160, resulted in biases of 13.9 % at an SIL-IS concentration of 0.7 mg/L. Conclusions: Applying this method will mitigate cross-signal contribution from the analyte isotopes to the corresponding SIL-IS, minimise the use of SIL-IS, and, thereby, reduce overall cost.

Efficacy and safety of cannabidivarin treatment of epilepsy in girls with Rett syndrome: A phase 1 clinical trial.

OBJECTIVE: Rett syndrome (RTT), commonly caused by methyl-CpG-binding protein 2 (MECP2) pathogenic variants, has many comorbidities. Fifty to ninety percent of children with RTT have epilepsy, which is often drug-resistant. Cannabidivarin (CBDV), a non-hallucinogenic phytocannabinoid, has shown benefit in MECP2 animal models. This phase 1 trial assessed the safety and tolerability of CBDV in female children with RTT and drug-resistant epilepsy, as well as the effect on mean monthly seizure frequency (MMSF), the electroencephalogram (EEG), and non-epilepsy comorbid symptoms. METHODS: Five female children with drug-resistant epilepsy and a pathogenic MECP2 variant were enrolled. Baseline clinical and laboratory assessments, including monthly seizure frequency, were recorded. CBDV oral solution (50 mg/ml) was prescribed and titrated to 10 mg/kg/day. Data collected included pharmacokinetics, seizure type and frequency, adverse events, EEG, and responses to the Rett Syndrome Behaviour Questionnaire and Rett Syndrome Symptom Severity Index, and were compared to baseline data. RESULTS: All five children reached the maximum CBDV dose of 10 mg/kg/day and had a reduction in MMSF (median = 79% reduction). Three children had MMSF reduction > 75%. This corresponded to an overall reduction in seizure frequency from 32 to 7.2 seizures per month. Ninety-one percent of adverse events were mild or moderate, and none required drug withdrawal. Sixty-two percent were judged to be unrelated to CBDV. Thirty-one percent of adverse events were identified as possibly related, of which nearly all were mild, and the remainder were later assessed as RTT symptoms. Hypersomnolence and drooling were identified as related to CBDV. No serious adverse events reported were related to CBDV. No significant change was noted in EEG or non-epilepsy-related symptoms of RTT. SIGNIFICANCE: A dose of 10 mg/kg/day of CBDV is safe and well tolerated in a pediatric RTT cohort and suggests improved seizure control in children with MECP2-related RTT.

Measurement of 5- fluorouracil, capecitabine and its metabolite concentrations in blood using volumetric absorptive microsampling technology and LC-MS/MS.

5-fluorouracil (5-FU) and its oral formulation, capecitabine, are widely used in treating a range of malignancies, either alone or in combination with other antineoplastic drugs. Body surface area-based dosing is used for these agents, despite this approach leading to substantial variability in drug exposure and often resulting in either toxicity or treatment failure. Tailoring therapeutic regimens for individual patients using therapeutic drug monitoring (TDM) has been shown to significantly reduce toxicity and improve cancer outcomes. However, for optimum TDM, sample timing is crucial, along with the need for a venepuncture blood sample to obtain the plasma currently used for 5-FU measurement. In addition to complex blood sample handling requirements, large sample volume and frequent sampling required for pharmacokinetic analysis is another barrier to successfully implementing TDM in a healthcare setting. Microsampling is an alternative collection method to venepuncture, which, combined with the now readily available liquid chromatography mass spectrometry (LC-MS/MS) technology, overcomes the plasma-associated issues. It also has the significant advantage of enabling at home and remote sampling, thus facilitating 5-FU TDM in clinical practice. A LC-MS/MS method for simultaneous measurement of capecitabine, 5'-deoxy-5-fluorocytidine, 5'-deoxy-5-fluorouridine and 5-FU using Mitra® microsampling devices for sample collection was developed. A Shimadzu 8060 LC-MS/MS equipped with electrospray ionisation source interface, operated in positive and negative ion modes, with reversed-phase chromatographic separation was employed for sample analysis. Samples were extracted from Mitra® devices using acetonitrile containing stable isotope-labelled internal standards, sonicated, evaporated under vacuum and resuspended in 0.1 % formic acid before injection into the LC-MS/MS. Chromatographic separation was on a Luna Omega Polar C18 (100 × 2.1 mm, 1.6 µm) column with gradient elution of 0.1 % formic acid in water and acetonitrile. Total run time was 5 min, with the injection volume of 1 µL. The intra and inter-day imprecision ranged from 3.0 to 8.1 and 6.3-13.3 % respectively. Accuracy ranged from 95 -114 % for all analytes. Lower limit of quantification with imprecision of < 19 % and accuracy between 89 and 114 % was 0.05 mg/L for 5-FU and 10 µg/L for other analytes. Assays were linear from 0.05 to 50 mg/L for 5-FU and 10-10,000 µg/L for all other analytes. Analytes were stable on Mitra® devices for up to 9 months at room temperature, 2 years at -30 ℃ and 3 days at 50 ℃. The method was successfully applied for the analysis of samples from patients undergoing cancer treatment with 5-FU and capecitabine. Microsampling using volumetric absorptive microsampling proved to be as reliable as conventional blood collection for 5-FU and capecitabine. This sampling technique may lead to less invasive and better-timed sample collection for TDM, supporting dose optimization strategy.

Pharmacokinetics, Safety, and Tolerability of a Medicinal Cannabis Formulation in Patients with Chronic Non-cancer Pain on Long-Term High Dose Opioid Analgesia: A Pilot Study.

INTRODUCTION: This phase I open-label study examined pharmacokinetics, safety, and tolerability of escalating doses of a novel combination cannabinoid medication (1:1 tetrahydrocannabinol [THC]/cannabidiol [CBD]) in patients with chronic non-cancer pain (CNCP) on high dose opioid analgesia. METHODS: Nine people with CNCP and oral morphine equivalent daily dose of 60 mg or higher were recruited. Blood concentrations of THC, 11-hydroxytetrahydrocannabinol (OH-THC), 11-nor-9-carboxy-tetrahydrocannabinol (COOH-THC), and CBD were assayed weekly. Concentrations were measured after a single dose of 2.5 mg THC/2.5 mg CBD on day 1, and daily escalating doses up to a single dose of 12.5 mg THC/12.5 mg CBD on day 29. Follow-up was on day 36 after a 7-day washout. Secondary outcome data encompassed pain, mood, and sleep parameters. RESULTS: The parent compounds THC, and CBD, and metabolites OH-THC and COOH-THC were detected at most time points. In general, the concentration of all analytes increased until 2 h post-administration, decreasing to approximately pre-dose concentrations by 8 h. There was considerable inter- and intra-individual variability. The study medication was well tolerated. Eight participants reported at least one adverse event (AE), with a total of 62 AEs; most common were euphoric mood, headache, and agitation, none classified as severe. There was no significant change to pain severity self-ratings, nor use of pain medications. Improvements in pain interference scores, mood, and some sleep parameters were observed. CONCLUSION: The THC/CBD formulation was tolerated well in a group of patients with CNCP. Between-participant variability supports personalized dosing and "start low-go slow" titration. To validate and quantify improvements in secondary efficacy outcomes a randomized placebo-controlled study is needed. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Register (CT-2019-CTN-01224-1).

Many studies use healthy volunteers when they look at the way medicines are absorbed in the body and their clinical effects. The aim of this project was to examine a new formulation of medicinal cannabis in people who have chronic pain and other health conditions to help us to plan a larger study. We wanted information on how quickly it was absorbed and whether there were any negative effects of the medicine. We wondered whether the fact that participants were on a number of other medications might mean that we see different results to those seen with healthy volunteers. We found that the results of our group were very similar to those seen in other studies. Although we only tested a small number of participants we did not observe serious negative effects of the medication, and saw some positive effects on mood and sleep. We now have the data to assist us in planning a larger study which should provide important guidance to prescribers of medicinal cannabis in the future.

Sodium alginate microencapsulation improves the short-term oral bioavailability of cannabidiol when administered with deoxycholic acid.

BACKGROUND: Cannabidiol (CBD) confers therapeutic effects in some neurological disorders via modulation of inflammatory, oxidative and cell-signalling pathways. However, CBD is lipophilic and highly photooxidative with low oral bioavailability in plasma and brain. In this study, we aimed to design and test a CBD microencapsulation method as a drug delivery strategy to improve the absorption of CBD. Additionally, we evaluated the brain uptake of CBD capsules when administered alongside capsules containing a permeation-modifying bile acid, deoxycholic acid (DCA). METHODS: Microcapsules containing either CBD or DCA were formed using the ionic gelation method with 1.5% sodium alginate formulations and 100 mM calcium chloride. C57BL/6J wild type mice randomly assigned to three treatment groups (3-4 mice per group) were administered CBD in the following preparations: 1) CBD capsules, 2) CBD capsules + DCA capsules and 3) naked CBD oil (control). To assess the short-term bioavailability of CBD, plasma and brain samples were collected at 0.3, 1 and 3 hours post administration and CBD levels were analysed with liquid chromatography mass spectrometer. RESULTS: We produced spherical capsules at 400 ± 50 µm in size. The CBD capsules were calculated to have a drug loading of 2% and an encapsulation efficiency of 23%. Mice that received CBD capsules + DCA capsules showed a 40% and 47% increase in CBD plasma concentration compared to mice on CBD capsules and naked CBD oil, respectively. Furthermore, the CBD capsules + DCA capsules group showed a 48% and 25% increase in CBD brain concentration compared to mice on CBD capsules and naked CBD oil, respectively. In mice treated with CBD capsules + DCA capsules, the brain CBD concentration peaked at 0.3 hours with a 300% increased availability compared to CBD capsules and naked CBD oil groups, which peaked at 1 hour after administration. CONCLUSIONS: The microencapsulation method combined with a permeation enhancer, DCA increased the short-term bioavailability of CBD in plasma and brain.

The 5-HT2C receptor as a therapeutic target for alcohol and methamphetamine use disorders: A pilot study in treatment-seeking individuals.

Alcohol use disorder (AUD) and methamphetamine use disorder (MUD) are prevalent and have high adverse impacts on both the individual and society. Current treatment strategies for these disorders are ineffective at a population level. Lorcaserin, a 5-HT2C receptor agonist, has shown potential at reducing the symptoms of substance use disorder. This pilot study (initiated prior to market withdrawal) examined feasibility and safety of lorcaserin treatment in people undergoing residential detoxification and treatment for AUD and MUD. This was an open label pilot study of lorcaserin where participants (n = 10 AUD; n = 8 MUD) received 10-mg lorcaserin daily for 4 days then twice daily for 1 month. Primary outcome measures included recruitment and retention rate, incidence of treatment-emergent events, incidence of methamphetamine or alcohol withdrawal-related events, heart rate, and blood pressure. Secondary measures included pharmacokinetic data and self-reported alcohol or methamphetamine use, craving, and psychological distress. AUD participants were recruited faster and had a greater retention rate compared with MUD participants. Lorcaserin did not alter vital signs, was well tolerated, and had a similar pharmacokinetic profile to individuals with obesity. Lorcaserin reduced self-reported alcohol and amphetamine-type substance use and craving in AUD and MUD participants, respectively. Self-reported psychological health also improved over the treatment period for all participants. Despite the pilot nature of this study, our data support the notion of 5-HT2C receptors as a therapeutic target for drug and alcohol abuse.

Overcoming barriers to implementing precision dosing with 5-fluorouracil and capecitabine.

Despite advances in targeted cancer therapy, the fluoropyrimidines 5-fluorouracil (5FU) and capecitabine continue to play an important role in oncology. Historically, dosing of these drugs has been based on body surface area. This approach has been demonstrated to be an imprecise way to determine the optimal dose for a patient. Evidence in the literature has demonstrated that precision dosing approaches, such as DPD enzyme activity testing and, in the case of intravenous 5FU, pharmacokinetic-guided dosing, can reduce toxicity and yield better patient outcomes. However, despite the evidence, there has not been uniform adoption of these approaches in the clinical setting. When a drug such as 5FU has been used clinically for many decades, it may be difficult to change clinical practice. With the aim of facilitating change of practice, issues and barriers to implementing precision dosing approaches for 5FU and capecitabine are identified and discussed with possible solutions proposed.

Barriers and opportunities for the clinical implementation of therapeutic drug monitoring in oncology.

There are few fields of medicine in which the individualisation of medicines is more important than in the area of oncology. Under-dosing can have significant ramifications due to the potential for therapeutic failure and cancer progression; by contrast, over-dosing may lead to severe treatment-limiting side effects, such as agranulocytosis and neutropenia. Both circumstances lead to poor patient prognosis and contribute to the high mortality rates still seen in oncology. The concept of dose individualisation tailors dosing for each individual patient to ensure optimal drug exposure and best clinical outcomes. While the value of this strategy is well recognised, it has seen little translation to clinical application. However, it is important to recognise that the clinical setting of oncology is unlike that for which therapeutic drug monitoring (TDM) is currently the cornerstone of therapy (e.g. antimicrobials). Whilst there is much to learn from these established TDM settings, the challenges presented in the treatment of cancer must be considered to ensure the implementation of TDM in clinical practice. Recent advancements in a range of scientific disciplines have the capacity to address the current system limitations and significantly enhance the use of anticancer medicines to improve patient health. This review examines opportunities presented by these innovative scientific methodologies, specifically sampling strategies, bioanalytics and dosing decision support, to enable optimal practice and facilitate the clinical implementation of TDM in oncology.

Ibudilast for prevention of oxaliplatin-induced acute neurotoxicity: a pilot study assessing preliminary efficacy, tolerability and pharmacokinetic interactions in patients with metastatic gastrointestinal cancer.

PURPOSE: This prospective, open-label, sequential 'before vs. after' pilot study was conducted to provide preliminary efficacy and tolerability data for ibudilast in the prevention of oxaliplatin-induced neurotoxicity in patients with metastatic upper gastrointestinal or colorectal cancer. Any potential impact of ibudilast on oxaliplatin and 5-fluorouracil pharmacokinetics was also explored. METHODS: Participants were administered a chemotherapy cycle (FOLFOX or CapeOx), followed by a chemotherapy cycle with co-administration of ibudilast 30 mg b.i.d. p.o. Efficacy was assessed on Day 3 and end of cycle using the Oxaliplatin-Specific Neurotoxicity Scale (OSNS) and additional clinical/patient-reported neurotoxicity measures. A population pharmacokinetic approach was used to determine oxaliplatin and 5-fluorouracil pharmacokinetics with and without ibudilast. RESULTS: Sixteen participants consented; 14 completed both chemotherapy cycles. Across all measures, the majority of participants experienced either an improvement or no worsening of neurotoxicity with ibudilast treatment. Based on OSNS assessments, acute neurotoxicity was unchanged in 12/14 participants and improved in 2/14 participants. The 90% confidence interval (CI) of the dose-normalised ratio of oxaliplatin AUC (90% CI 95.0-109%) and 5-fluorouracil AUC (90% CI 66.5-173%) indicated no significant impact of ibudilast on systemic exposure. CONCLUSION: This pilot study indicated ibudilast co-administration may improve or stabilise oxaliplatin-induced neurotoxicity. Given the expected worsening of symptoms in patients with continued chemotherapy, this represents a signal of effect that warrants further investigation. Pharmacokinetic analysis indicates ibudilast has no significant effect on oxaliplatin pharmacokinetics, and is unlikely to influence pharmacokinetics of 5-fluorouracil. CLINICAL TRIAL REGISTRATION: Trial registration number: UTN U1111-1209-0075 and ANZCTRN12618000232235 (registered 13/02/2018).