Neurotrophic receptor tyrosine kinase type 3 (NTRK3)

Neurotrophic receptor tyrosine kinase type 3 (NTRK3), also commonly known as TrkC, is a high-affinity receptor tyrosine kinase that specifically binds neurotrophin-3 (NT-3) (UniProt: Q16288). It plays a fundamental role in the development of the nervous system, particularly in the survival and differentiation of proprioceptive sensory neurons and the regulation of synaptic plasticity (NCBI Gene: 4916). Upon ligand binding, NTRK3 undergoes dimerization and autophosphorylation, triggering intracellular signaling cascades that promote cell survival and growth. In clinical oncology, NTRK3 is highly significant due to chromosomal rearrangements that result in NTRK3 gene fusions, such as the ETV6-NTRK3 fusion found in infantile fibrosarcoma and secretory breast carcinoma (PubMed: 30395155). These fusions lead to constitutive activation of the kinase domain, driving malignant transformation regardless of the tissue of origin. Consequently, NTRK3 has become a primary target for 'tumor-agnostic' precision medicines like larotrectinib and entrectinib, which provide high response rates in patients harboring these specific genetic alterations (FDA Label: Rozlytrek).

Other names

TrkCTropomyosin receptor kinase CNT-3 growth factor receptorGP145-TrkCTrk-C

Small molecule inhibitors target the tropomyosin receptor kinase (TRK) family (TRKA, TRKB, and TRKC) by competitively binding to the adenosine triphosphate (ATP) binding site of the kinase domain (FDA Label: Vitrakvi). This inhibition prevents receptor autophosphorylation and the subsequent activation of downstream signaling pathways, such as the MAPK/ERK, PI3K/Akt, and PLC-gamma cascades, which are essential for cell proliferation and survival (PubMed: 29470288). In the context of oncogenic fusions, these inhibitors specifically block the constitutive kinase activity driven by the fusion partner, leading to tumor growth arrest and apoptosis (PubMed: 30395155).