Inhibition of RAS-driven signaling and tumorigenesis with a pan-RAS monobody targeting the Switch I/II pocket

Lauren Wallon, Imran Khan, Kai Wen Teng, Akiko Koide, Mariyam Zuberi, Jianping Li, Gayatri Ketavarapu, Nathaniel J. Traaseth, John P. O’Bryan, Shohei Koide

Research output: Contribution to journalArticlepeer-review


RAS mutants are major therapeutic targets in oncology with few efficacious direct inhibitors available. The identification of a shallow pocket near the Switch II region on RAS has led to the development of small-molecule drugs that target this site and inhibit KRAS(G12C) and KRAS(G12D). To discover other regions on RAS that may be targeted for inhibition, we have employed small synthetic binding proteins termed monobodies that have a strong propensity to bind to functional sites on a target protein. Here, we report a pan-RAS monobody, termed JAM20, that bound to all RAS isoforms with nanomolar affinity and demonstrated limited nucleotide-state specificity. Upon intracellular expression, JAM20 potently inhibited signaling mediated by all RAS isoforms and reduced oncogenic RAS-mediated tumorigenesis in vivo. NMR and mutation analysis determined that JAM20 bound to a pocket between Switch I and II, which is similarly targeted by low-affinity, small-molecule inhibitors, such as BI-2852, whose in vivo efficacy has not been demonstrated. Furthermore, JAM20 directly competed with both the RAF(RBD) and BI-2852. These results provide direct validation of targeting the Switch I/II pocket for inhibiting RAS-driven tumorigenesis. More generally, these results demonstrate the utility of tool biologics as probes for discovering and validating druggable sites on challenging targets.

Original languageEnglish (US)
Article numbere2204481119
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number43
StatePublished - Oct 25 2022


  • drug discovery
  • synthetic binding protein
  • target validation
  • tool biologic

ASJC Scopus subject areas

  • General


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