The B7x Immune Checkpoint Pathway: From Discovery to Clinical Trial

Peter John, Yao Wei, Weifeng Liu, Meirong Du, Fangxia Guan, Xingxing Zang

Research output: Contribution to journalReview articlepeer-review

30 Scopus citations


B7x (B7 homolog x, also known as B7-H4, B7S1, and VTCN1) was discovered by ourselves and others in 2003 as the seventh member of the B7 family. It is an inhibitory immune checkpoint of great significance to human disease. Tissue-expressed B7x minimizes autoimmune and inflammatory responses. It is overexpressed in a broad spectrum of human cancers, where it suppresses antitumor immunity. Further, B7x and PD-L1 tend to have mutually exclusive expression in cancer cells. Therapeutics targeting B7x are effective in animal models of cancers and autoimmune disorders, and early-phase clinical trials are underway to determine the efficacy and safety of targeting B7x in human diseases. It took 15 years moving from the discovery of B7x to clinical trials. Further studies will be necessary to identify its receptors, reveal its physiological functions in organs, and combine therapies targeting B7x with other treatments.

Original languageEnglish (US)
Pages (from-to)883-896
Number of pages14
JournalTrends in Pharmacological Sciences
Issue number11
StatePublished - Nov 2019


  • B7x
  • autoimmunity
  • cancer
  • immune checkpoint
  • immunotherapy
  • inflammation

ASJC Scopus subject areas

  • Toxicology
  • Pharmacology


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