Next-generation sequencing from chronic myeloid leukemia dried blood spots: insights and implications for global...

The goal of the "Spot On CML" program is to provide diagnostic and monitoring tests to chronic myeloid leukemia (CML) patients in low- and middle-income countries (LMICs). Previously, we demonstrated reproducible BCR::ABL1 transcript quantification using dried blood spots (DBS). We have now optimized methods of DNA and RNA extraction from DBS, allowing the detection of myeloid gene variants, including ABL1 tyrosine kinase domain mutations. Among 177 CML patients from nine countries, ABL1 mutations were identified in 61 (34%) patients, with multiple mutations present in some cases. The most common ABL1 mutation was T315I (45.9% of patients with ABL1 mutations). Among 69 patients, 89 Tier I-II variants (pathogenic or likely pathogenic) were identified in other genes, including 52 ASXL1 variants in 49 patients. The detection of ASXL1 variants correlated strongly with the presence of ABL1 mutations (P = 3.51E-04). These methodologies are directly applicable to all assays used for the diagnosis, prognosis, and monitoring of CML and have important implications in bringing state-of-the-art genetic analysis to CML patients in LMICs.