On TRacK With Larotrectinib in a Neonate With a Giant Congenital ETV6::NTRK3 Fusion-Positive Infantile Fibrosarcoma of the Head and Neck.

Abstract

Infantile fibrosarcoma (IFS) is a rare pediatric tumor of intermediate malignancy with high local aggressiveness that typically presents in young infants. Its occurrence in the head and neck region is rare. Complete non-mutilating surgical resection is often not possible, requiring multimodal treatment. IFS frequently harbors neurotrophic receptor tyrosine kinase (NTRK) fusions. Targeted therapy with NTRK inhibitors is modifying treatment paradigms of IFS. Herein, we report the case of a neonate with a giant unresectable congenital ETV6::NTRK3 (+) IFS of the head and neck region without rapid response to chemotherapy who was treated with larotrectinib oral suspension. Larotrectinib was well tolerated and induced an impressive clinical and radiologic response. This case illustrates an example of pediatric precision oncology in a neonate with an ETV6::NTRK3 (+) congenital IFS of the head and neck region and provides further reference for the use of larotrectinib in the neonatal period.