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

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.

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.

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).

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.