Class III and IV Receptor Tyrosine Kinases (Class III/IV RTKs)

Class III and IV Receptor Tyrosine Kinases (RTKs) are essential cell-surface receptors characterized by an intracellular split tyrosine kinase domain and extracellular immunoglobulin-like loops (UniProt). Class III RTKs, including PDGFR, KIT, and FLT3, are vital for hematopoiesis and mesenchymal cell growth, while Class IV RTKs (FGFR1-4) regulate angiogenesis and embryonic development (PubMed: 21549330). Mutations or over-expression in these families are strongly linked to cancers such as Acute Myeloid Leukemia (FLT3) and Gastrointestinal Stromal Tumors (KIT) (NIH/NCI). Therapeutic intervention typically involves small-molecule inhibitors like Imatinib or Midostaurin, which compete for the ATP-binding site to halt oncogenic signaling (PubChem). However, targeting these receptors can lead to systemic toxicities, including myelosuppression and hypertension, due to their roles in normal physiological processes (StatPearls).

Other names

PDGFR familyFGFR familySplit-kinase domain receptorsType III and IV RTKsPlatelet-derived growth factor receptor familyFibroblast growth factor receptor family

Small-molecule inhibitors typically act through ATP-competitive inhibition of the intracellular tyrosine kinase domain, preventing autophosphorylation and the subsequent activation of downstream signaling pathways such as PI3K/AKT, MAPK/ERK, and STAT.