Inactive tyrosine-protein kinase 7 (PTK7)

Inactive tyrosine-protein kinase 7 (PTK7), also known as Colon carcinoma kinase 4 (CCK4), is a member of the receptor tyrosine kinase (RTK) family that lacks detectable catalytic activity, classifying it as a pseudokinase (UniProt P35091). Despite its lack of kinase activity, PTK7 functions as a critical scaffold and co-receptor in the non-canonical Wnt signaling pathway, where it regulates cell polarity, migration, and tissue morphogenesis during embryonic development (NCBI Gene: 5754). In adult tissues, PTK7 expression is generally low, but it is significantly upregulated in various malignancies, including lung, breast, and colorectal cancers, where it is associated with increased tumor invasiveness and poor prognosis (PMID: 33430931). This differential expression profile makes PTK7 an attractive target for therapeutic intervention, particularly for antibody-drug conjugates (ADCs). For example, cofetuzumab pelidotin (PF-06647020) is an ADC designed to bind PTK7 and deliver a potent microtubule inhibitor directly into cancer cells (PMID: 28455364). Beyond its role as a drug target, PTK7 is also being investigated as a biomarker for cancer stem cells and metastatic potential in solid tumors.

Other names

Colon carcinoma kinase 4CCK4Protein-tyrosine kinase 7CCK-4

Antibody-drug conjugate (ADC) targeting PTK7 to deliver cytotoxic payloads (e.g., Auristatin-0101) to tumor cells; potential modulation of non-canonical Wnt signaling pathways.