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Abstract Microsampling lancet-induced blood drops enables frequent and comprehensive analysis of various metabolites, lipids, cytokines, and proteins. This approach holds promise for monitoring immunotherapy patients using RNA biomarkers, but a suitable method for processing RNA has been lacking. In this study, we employed a targeted RNA-sequencing protocol, the DriverMap™ EXP assay, to process 30 ul of dried blood. We compared the gene expression profile in traditionally collected blood samples with that of blood absorbed onto a Mitra® microsampling device containing an RNA-stabilization reagent. Following endotoxin incubation, RNA was extracted from stimulated and unstimulated blood samples. Targeted PCR amplification of 274 immune/inflammatory genes using the DriverMap targeted RNA-Seq protocol demonstrated robust detection and high correlation (r = 0. 94) between the two methods in both unstimulated and endotoxin-stimulated blood. Moreover, differentially expressed genes (DEGs) identified in standard and microsampling methods exhibited substantial overlap with publicly available datasets from similar experiments. Furthermore, we compared whole blood extracted from Tempus™ blood RNA tubes to Mitra microsamples pre- and post-immunization with the Pneumovax® vaccine using the DriverMap EXP genome-wide 19K panel for targeted RNA-sequencing. We observed approximately 90% overlap in the top 10K genes between Tempus and Mitra microsamples. Notably, microsamples stored at 4ºC for over a year exhibited similar expression profiles to more recently drawn whole blood samples. Citation Format: Lester Kobzik, Tianbing Liu, Mikhail Makhanov, Dongfang Hu, Khadija Ghias, Paul Diehl, Alex Chenchik. Targeted RNA-seq of dried blood microsamples for convenient RNA biomarker monitoring abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 5643.
Kobzik et al. (Fri,) studied this question.