Cladribine therapy for advanced and indolent systemic mastocytosis: Mayo Clinic experience in 42 consecutive cases

Ayalew Tefferi, Jaya Kittur, Faiqa Farrukh, Kebede H. Begna, Mrinal M. Patnaik, Aref Al-Kali, Michelle A. Elliott, Kaaren K. Reichard, Naseema Gangat, Animesh Pardanani

Research output: Contribution to journalArticlepeer-review


We describe our single institution experience with cladribine therapy in 42 patients with systemic mastocytosis (SM): 22 advanced (adv-SM; median age 65 years, 68% males) and 20 indolent/smouldering SM (ISM/SSM; median age 56 years, 45% males); subcategories included eight aggressive, 13 associated with another haematological neoplasm, one mast cell leukaemia, 17 ISM and three SSM. Overall/major response rates were 77%/45% for adv-SM and 70%/60% for ISM/SSM, and median (range) duration of response 10 (4–75) and 46 (4–140) months respectively. A >50% reduction in bone marrow mast cell burden and serum tryptase level was documented in 63% and 67% of patients with adv-SM and 50% and 46% with ISM/SSM respectively. The presence of KIT proto-oncogene, receptor tyrosine kinase (KIT)D816V predicted response in adv-SM: 17 (90%) of 19 with and none of three without the mutation responded (P < 0·01). Treatment-emergent adverse events were mostly limited to transient cytopenias: Grade 3/4 neutropenia, thrombocytopenia, or lymphopenia occurred in 27%, 27% and 27% of patients with adv-SM, and 5%, 5% and 30% with ISM/SSM respectively. The present study provides practical information that might be considered when making treatment choices between cladribine and newer KIT-targeted therapies and identifies the absence of KITD816V as a potential marker of cladribine resistance in advanced SM; the latter observation needs confirmation in a larger study.

Original languageEnglish (US)
Pages (from-to)975-983
Number of pages9
JournalBritish journal of haematology
Issue number4
StatePublished - Feb 2022


  • 2-chlorodeoxyadenosine
  • KIT
  • avapritinib
  • midostaurin
  • mutation

ASJC Scopus subject areas

  • Hematology


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