PTK7 is a highly conserved but catalytically inactive receptor tyrosine kinase in the Wnt signaling pathway, which has been shown preclinically to be enriched on tumor initiating cells (TICs) in several tumor types.1

  • Protein tyrosine kinase 7 (PTK7) belongs to the receptor tyrosine kinase family with an inactive kinase domain2
  • PTK7, also known as colon carcinoma kinase 4 (CCK-4), is upregulated in various cancers, where it is known to act as either an oncoprotein or a tumor suppressor3


  • An unbiased analysis of isolated TIC populations provided the first indication that PTK7 is enriched on TICs.1
  • Next-generation whole transcriptome sequencing of functionally tumorigenic cell subpopulations showed higher PTK7 expression on TICs from triple negative breast cancer (TNBC) and ovarian cancer patient-derived xenografts compared to normal tissues.1
  • PTK7 is also highly overexpressed in a variety of tumors, such as colon cancer, lung adenocarcinoma, acute myelogenous leukemia, and gastric cancer.2
  • Knocking down PTK7 expression in esophageal squamous cell carcinoma (ESCC) stem-like cells reduced their sphere formation, promoted apoptosis, and suppressed their migration and invasion abilities.4
    • Knocking down PTK7 also inhibits tumor progression in TNBC.5

Oncogenic Expression


  • In a panel of protein lysates from derived xenografts PTK7 expression was observed in 12 of 12 (100%) patient-derived xenografts.
  • PTK7 not only correlates with worse prognosis, but also associates with tumor metastasis and progression.5
  • PTK7 promotes cancer proliferation and migration.5


  • In a panel of protein lysates from derived xenografts higher PTK7 expression in NSCLC is associated with significantly shorter survival and it was observed that PTK7 enriches for TICs in NSCLC.1
  • Studies have demonstrated that inhibition of PTK7 reduces the number of TICs and induces tumor regression.6


  • In a panel of protein lysates from derived xenografts PTK7 expression was observed in 43 of 47 (91%) patient-derived xenografts.1
  1. Damelin M, et al. A PTK7-targeted antibody-drug conjugate reduces tumor-initiating cells and induces sustained tumor regressions. Sci Transl Med. 2017;9(372). pii: eaag2611.
  2. Sun J-J, et al. The increased PTK7 expression is a malignant factor in cervical cancer. Hindawi Disease Markers. Volume 2019. Article ID 5380197. 10 pages.
  3. Shin W-S, et al. Biphasic regulation of tumorigenesis by PTK7 expression level in esophageal squamous cell carcinoma. Scientific Reports. Volume 8. Article number: 8519 (2018).
  4. Bie J, et al. PTK7 promotes the malignant properties of cancer stem-like cells in esophageal squamous cell lines. Human cell. 2020 Apr;33(2):356-65.
  5. Cui NP, et al. Protein tyrosine kinase 7 (PTK7) regulates EGFR/Akt signaling pathway and correlates with malignant progression in triple-negative breast cancer. Frontiers in Oncology. 2021;11:2887.
  6. Chen B, et al. Immune related genes and gene sets for predicting the response to anti programmed death 1 therapy in patients with primary or metastatic non small cell lung cancer. Oncology Letters. 2021 Jul 1;22(1):1-2.