Successful targeted treatment of mast cell activation syndrome with tofacitinib

Lawrence B. Afrin, Roger W. Fox, Susan L. Zito, Leo Choe, Sarah C. Glover

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


Mast cell (MC) activation syndrome (MCAS) is a collection of illnesses of inappropriate MC activation with little to no neoplastic MC proliferation, distinguishing it from mastocytosis. MCAS presents as chronic, generally inflammatory multisystem polymorbidity likely driven in most by heterogeneous patterns of constitutively activating mutations in MC regulatory elements, posing challenges for identifying optimal mutation-targeted treatment in individual patients. Targeting commonly affected downstream effectors may yield clinical benefit independent of upstream mutational profile. For example, both activated KIT and numerous cytokine receptors activate the Janus kinases (JAKs). Thus, JAK-inhibiting therapies may be useful against the downstream inflammatory effects of MCAS. The oral JAK1/JAK3 inhibitor, tofacitinib, is currently approved for rheumatoid arthritis and is in clinical trials for other chronic inflammatory disorders. Herein, we report two patients with MCAS who rapidly gained substantial symptomatic response to tofacitinib. Their improvement suggests need for further evaluation of this class of drugs in MCAS treatment.

Original languageEnglish (US)
Pages (from-to)190-193
Number of pages4
JournalEuropean Journal of Haematology
Issue number2
StatePublished - Aug 2017
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd


  • JAK inhibitors
  • KIT activation
  • dysautonomia
  • fibromyalgia
  • mast cell activation syndrome
  • mast cells
  • rheumatoid arthritis
  • tofacitinib


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