Monitoring of Imatinib in Fingerprints by LC-MS/MS: Method Development and Validation

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INTRODUCTION: Imatinib (IM) is the first tyrosine kinase inhibitor (TKI) approved for the treatment of chronic myeloid leukemia (CML). Evaluating treatment adherence is crucial, as a satisfactory response is associated with adherence rates above 95%. The use of fingerprint analysis to assess therapeutic adherence has been proposed in the literature as a non-invasive collection strategy with high stability.OBJECTIVE: To develop and validate an innovative and non-invasive methodology for monitoring IM concentrations in fingerprints using UPLC-MS/MS. MATERIALS/METHODS: Sweat samples were collected from patients’ fingerprints, which were printed for 30 seconds on glass slides after using non-talc gloves for 5 minutes. Calibrators were prepared in methanol and applied to slides with blank fingerprints. The analyte was extracted from the slide using a mixture of methanol and acetonitrile, utilizing the internal standard imatinib-D8. A total of 250 µL of extraction solvent was applied to the slide. After 12 to 15 seconds, the content was transferred to a 1.5 mL polypropylene tube, and the extraction process was repeated twice. The samples were concentrated at 60°C for 45 minutes. After evaporation, the extract was resuspended in 100 µL of methanol. The analysis was conducted on a UPLC-MS/MS Xevo® TQD-micro system with electrospray ionization in positive mode. A C18 column (10 × 2.1 mm, 1.7 µm) was used at 40°C with gradient elution of water containing 0.1% formic acid (A) and acetonitrile containing 0.1% formic acid (B), ranging from 40% to 90% B. The method was validated according to FDA guidelines. IM concentrations in fingerprints and plasma from 11 CML patients were compared.RESULTS: The analytical run time was 6 minutes, with elution of imatinib and the internal standard at 1.7 minutes. The method exhibited precision (CV < 5.7%) and accuracy (89-103%), with an extraction yield of 98%. The calibration curve was linear between 500 and 5,000 pg/slide (r > 0.99 in 1/x). Imatinib concentrations in fingerprints ranged from 110 to 2,280 pg/slide and showed a significant correlation (r = 0.67, p < 0.01) with plasma levels ranging from 731 ng/mL to 2,210 ng/mL. Two patients were considered nonadherent to treatment, showing undetectable IM levels in both matrices. CONCLUSION: The use of fingerprints to monitor imatinib concentrations has proven to be viable, with consistent detection. This technique has potential to be explored as a practical and non-invasive alternative for evaluating treatment adherence.