DDR1 and biliary tract neoplasm: DDR dysregulation is currently considered one of the most relevant intracellular pathways in regulating proliferation, apoptosis and chemoresistance in biliary tract cancers (BTC) [64,70], as germline or somatic mutations in DDR genes were found in the majority of patients (63.5% [67]) and the presence of mutations/alterations in the expression of specific DDR genes can impact on patient response to platinum-based regimens [67,71,72,73,74].