Drug Response Variants May Be Distinct in Somatic, Germline Samples

For a paper appearing in The Pharmacogenomics Journal, researchers at the University of North Carolina-Chapel Hill, the Moffitt Cancer Center and Research Institute, and the University of Tennessee Health Science Center compare pharmacogenomics-related variants in tumor-only sequence data and sequences generated from matched germline samples. The team tracked down somatic mutations affecting one or more drug response genes in 44 percent of patients when it analyzed 21 drug response-related genes in tumor and matched normal blood samples from more than 750 solid cancer patients — but the somatic mutations did not always match those found in germline sequences. "Determining how to utilize tumor-only sequencing protocols to inform the most effective and safe drug therapies for treating cancer and other co-morbidities in oncology patients is essential for furthering precision medicine," the authors write, noting that the current study suggests that while it "does not allow definitive classification of patient germline genotypes for drug response genes," tumor-only sequencing may still "raise suspicion about the presence of an actionable pharmacogenomic variant, thus triggering further genetic testing from patient germline DNA."