The FDA approved the next-generation sequencing-based FoundationOne CDx test as a companion diagnostic to identify patients with neurotrophic receptor tyrosine kinase (NTRK) gene fusions eligible for treatment with larotrectinib, according to a press release.  

The indication includes patients with solid tumors with fusions in NTRK1, NTRK2, or NTRK3.  

The FDA granted accelerated approval to larotrectinib on November 26, 2019 for adult and pediatric patients with solid tumors that have a NTRK gene fusion, “that are either metastatic or where surgical resection is likely to result in severe morbidity, and who have no satisfactory alternative treatments or whose cancer has progressed following treatment.” 

The FDA based its approval of larotrectinib on three open-label, single arm clinical trials (LOXO-TRK-14001, SCOUT, NAVIGATE).  

During the trials, NTRK fusion status was prospectively determined by local laboratories using next-generation sequencing,  fluorescence in situ hybridization, and reverse transcriptase- polymerase chain reaction method.  

The FoundationOne CDx assay was approved based on the retrospective testing of available tissue samples from patients enrolled in the three clinical trials supporting larotrectinib’s accelerated approval. 

Efficacy for larotrectinib was maintained in patients confirmed to have NTRK fusion positive results from the CDx assay.   


By Cassie Homer