Volumetric Absorptive Microsampling as a New Biosampling Tool for Monitoring of Tamoxifen, Endoxifen, 4-OH Tamoxifen and N-Desmethyltamoxifen in Breast Cancer Patients

An LC-MS/MS method for tamoxifen and six metabolites in VAMS was developed and validated, with water prerinsing improving recoveries and poor room temperature stability but stability for at least 100 days at minus 80 degrees Celsius. Plasma to blood ratios were used to estimate plasma equivalent concentrations, and paired VAMS and plasma samples from ten breast cancer patients showed strong correlations and good agreement on Bland-Altman analysis, supporting reliable decentralised TDM.

Development and validation of an LC-MS/MS method for the comprehensive quantification of tamoxifen and its metabolites in volumetric absorptive microsampling: clinical application in breast cancer patients — Kuo et al., Analytical and bioanalytical chemistry (paywalled) · source ↗

• blood
• dried
• vams
• neoteryx-mitra
• validation
• venous-agreement
• tdm
• oncology

The study developed and validated a reliable HPLC-MS method for quantifying multiple tyrosine kinase inhibitors from VAMS microsamples of capillary blood, showing acceptable accuracy, precision, and 28-day stability at -21°C, with results comparable to venous plasma in 194 samples from patients with solid tumours. This enables therapeutic drug monitoring using microsamples in oncology practice.

HPLC-MS Quantification of Multiple Tyrosine Kinase Inhibitors in Patients with Solid Tumors: Method Validation and Clinical Application — Staudinger et al., Pharmaceutics (paywalled) · source ↗

• blood
• dried
• capillary
• vams
• neoteryx-mitra
• validation
• tdm
• oncology

Microsampling with Mitra® devices correlated strongly with venous plasma for capecitabine therapeutic drug monitoring (r=0.97), but yielded consistently lower concentrations. Patients preferred this method and reported minimal pain, suggesting it is suitable for patient-centric oncology drug monitoring in decentralised settings.

Comparison of capecitabine concentrations determined by microsampling versus plasma concentrations for therapeutic drug monitoring: a pilot study — Shafiei et al., The Journal of pharmacy and pharmacology (paywalled) · source ↗

• blood
• dried
• capillary
• vams
• neoteryx-mitra
• validation
• venous-agreement
• acceptability
• tdm
• oncology

The study validated an LC-HRMS method for measuring breast cancer drugs in plasma, urine, VAMS and oral fluid, showing that all matrices except oral fluid for certain drugs can support decentralised therapeutic drug monitoring. VAMS and oral fluid faced practical challenges in collection due to patient conditions, but the method enables patient-centric monitoring with dried blood and other self-collected samples.

Towards clinical adherence monitoring of oral endocrine breast cancer therapies by LC-HRMS-method development, validation, comparison of four sample matrices, and proof of concept — Jacobs et al., Analytical and bioanalytical chemistry · source ↗

• blood
• saliva
• urine
• dried
• vams
• neoteryx-mitra
• validation
• tdm
• oncology

An on-line SPE-LC-MS method using 10 microlitre capillary blood samples collected on VAMS tips achieved lower limits of quantitation of 0.03 micromolar for methotrexate and 7-OH-MTX and 0.05 micromolar for DAMPA, with acceptable accuracy and precision. A plasma-to-whole-blood correlation factor of 0.46 was observed, supporting low-volume pediatric drug monitoring.

Development and validation of a bioanalytical method for the quantification of methotrexate from serum and capillary blood using volumetric absorptive microsampling (VAMS) and on-line solid phase extraction (SPE) LC-MS — Opitz et al., Journal of chromatography. A (paywalled) · source ↗

• blood
• dried
• capillary
• vams
• neoteryx-mitra
• validation
• pediatric
• tdm
• oncology