Genetic basis for iMCD-TAFRO

Akihide Yoshimi, Memorial Sloan-Kettering Cancer Center
Tanya M. Trippett, Memorial Sloan-Kettering Cancer Center
Nan Zhang, University at Buffalo, The State University of New York
Xueyan Chen, University of Washington
Alexander V. Penson, Memorial Sloan-Kettering Cancer Center
Maria E. Arcila, Memorial Sloan-Kettering Cancer Center
Janine Pichardo, Memorial Sloan-Kettering Cancer Center
Jeeyeon Baik, Memorial Sloan-Kettering Cancer Center
Allison Sigler, Memorial Sloan-Kettering Cancer Center
Hironori Harada, Tokyo University of Pharmacy and Life Sciences
David C. Fajgenbaum, Castleman Disease Collaborative Network
Ahmet Dogan, Memorial Sloan-Kettering Cancer Center
Omar Abdel-Wahab, Memorial Sloan-Kettering Cancer Center
Wenbin Xiao, Memorial Sloan-Kettering Cancer Center

Abstract

TAFRO syndrome, a clinical subtype of idiopathic multicentric Castleman disease (iMCD), consists of a constellation of symptoms/signs including thrombocytopenia, anasarca, fever, reticulin fibrosis/renal dysfunction, and organomegaly. The etiology of iMCD-TAFRO and the basis for cytokine hypersecretion commonly seen in iMCD-TAFRO patients has not been elucidated. Here, we identified a somatic MEK2 mutation and a germline RUNX1 mutation in two patients with iMCD-TAFRO, respectively. The MEK2 mutation, which has been identified previously in solid tumor and histiocytosis patients, caused hyperactivated MAP kinase signaling, conferred IL-3 hypersensitivity and sensitized the cells to various MEK inhibitors. The RUNX1 mutation abolished the transcriptional activity of wild-type RUNX1 and functioned as a dominant negative form of RUNX1, resulting in enhanced self-renewal activity in hematopoietic stem/progenitor cells. Interestingly, ERK was heavily activated in both patients, highlighting a potential role for activation of MAPK signaling in iMCD-TAFRO pathogenesis and a rationale for exploring inhibition of the MAPK pathway as a therapy for iMCD-TAFRO. Moreover, these data suggest that iMCD-TAFRO might share pathogenetic features with clonal inflammatory disorders bearing MEK and RUNX1 mutations such as histiocytoses and myeloid neoplasms. P128L G60C P128L G60C