Neurotrophic receptor tyrosine kinase fusion protein (NTRK fusion kinase) (NTRK fusion kinase)

Neurotrophic receptor tyrosine kinase (NTRK) fusion proteins are chimeric oncoproteins formed by chromosomal rearrangements that join the 3' kinase domain of the NTRK1, NTRK2, or NTRK3 genes with various 5' fusion partners (NIH, 2023). These fusions result in the constitutive, ligand-independent activation of the tropomyosin receptor kinase (TRK) signaling cascade, which normally regulates neuronal development and survival (UniProt, 2024). In a malignant context, the aberrant signaling through pathways such as MAPK/ERK and PI3K/AKT drives uncontrolled cell growth and survival across a diverse range of adult and pediatric solid tumors (PubMed, PMID: 30333493). NTRK fusions are rare in common cancers like lung or colorectal cancer but are pathognomonic in rare tumors such as infantile fibrosarcoma and secretory breast carcinoma (StatPearls, 2023). Small-molecule inhibitors like larotrectinib and entrectinib have revolutionized treatment by providing high efficacy regardless of the tumor's tissue of origin, marking a shift toward histology-agnostic precision medicine (FDA, 2018). Despite their success, clinicians must manage unique side effects related to TRK's role in the nervous system, such as dizziness and weight gain, as well as the emergence of secondary resistance mutations in the kinase domain (PubMed, PMID: 32060151). Next-generation inhibitors like repotrectinib are being developed to overcome these resistance mechanisms, specifically targeting solvent-front mutations (PubMed, PMID: 31064703). Identification of these fusions typically requires advanced diagnostic techniques such as next-generation sequencing or fluorescence in situ hybridization to ensure appropriate patient selection (NCCN, 2023).

Other names

TRK fusion proteinNTRK1/2/3 fusionTropomyosin receptor kinase fusionOncogenic NTRK rearrangementNTRK chimeric protein

Selective inhibition of the tropomyosin receptor kinase (TRK) catalytic domain to prevent downstream signaling through the MAPK, PI3K, and PLCγ pathways.