Identification of NTRK fusions in pediatric mesenchymal tumors

Background NTRK fusions are known oncogenic drivers and have recently been effectively targeted by investigational agents in adults. We sought to assess the frequency of NTRK fusions in a large series of pediatric and adolescent patients with advanced cancers. Procedure Genomic profiles from 2,031 advanced cancers from patients less than 21 years old who were assayed with comprehensive genomic profiling were reviewed to identify NTRK fusions. Results Total of nine cases (0.44%) harbored NTRK fusions, including novel partners. Four of these cases were in children less than 2 years old for which infantile fibrosarcoma was considered as a diagnosis, and two harbored the canonical ETV6-NTRK3. The remaining cases carried other diagnoses, at least one that carried the diagnosis of inflammatory myofibroblastic tumor. Conclusions NTRK fusions occur in a subset of young patients with mesenchymal or sarcoma-like tumors at a low frequency, and are eminently druggable targets via either investigational agents or approved drugs.