NTRK1 and cancer: In this respect, the FDA-approved Trk inhibitor “Larotrectinib” is of particular therapeutic interest, as it inhibits the activity of fusion, mutation and deletion-activated TrkA oncogenes, exhibits remarkable durable efficacy in a wide range of advanced stage human cancers driven by TrkA oncogenes [16–18] and could be tested, as third line therapy, in this MCPyV positive TrkAIII expressing MCC subtype.