Validation of Capillary Microsampling for Therapeutic Drug Monitoring of CDK4/6 Inhibitors in Breast Cancer Patients (TDHOME)

Therapeutic drug monitoring (TDM) could serve as a valuable tool to minimize adverse events and maximize the efficacy of treatment in breast cancer patients receiving CDK4/6 inhibitors (ribociclib, abemaciclib, palbociclib). However, current TDM performed via venous blood draws can be inconvenient, especially for repeated sampling.

This study aims to evaluate the reliability of capillary (fingertip) microsampling-which could be performed at home as a less invasive alternative to standard venous sampling for measuring residual drug concentrations.

Five blood samples will be collected at a single time point during treatment, in accordance with the routine TDM schedule (the treatment duration will remain as per the prescribed CDK4/6 regimen): 4 capillary samples (using the VAMS Mitra device) including 2 samples collected by the study nurse who will train the patient to perform the 2 following samples him/herself; and 1 venous sample (5 mL heparinized tube).

Inclusion criteria

• Adult patients (≥ 18 years) with breast cancer.
• Patients currently receiving ribociclib, abemaciclib, or palbociclib.
• Patients capable of performing capillary sampling (with or without assistance).
• Patient information and signing of informed consent.
• Patient ability to comply with protocol requirements.
• Patients covered by a health insurance system.

Exclusion criteria

• Patients with altered mental status or psychiatric disorder that, in the opinion of the investigator, would preclude a valid patient informed consent.
• Persons deprived of their liberty or under guardianship.