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Targeting human CALR‐mutated MPN progenitors with a neoepitope‐directed monoclonal antibody
Author(s) -
Tvorogov Denis,
ThompsonPeach Chloe A L,
Foßelteder Johannes,
Dottore Mara,
Stomski Frank,
Onnesha Suraiya A,
Lim Kelly,
Moretti Paul A B,
Pitson Stuart M,
Ross David M,
Reinisch Andreas,
Thomas Daniel,
Lopez Angel F
Publication year - 2022
Publication title -
embo reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.584
H-Index - 184
eISSN - 1469-3178
pISSN - 1469-221X
DOI - 10.15252/embr.202152904
Subject(s) - calreticulin , myelofibrosis , thrombopoietin receptor , biology , cancer research , mutant , mutation , microbiology and biotechnology , thrombopoietin , bone marrow , immunology , endoplasmic reticulum , stem cell , genetics , haematopoiesis , gene
Calreticulin (CALR) is recurrently mutated in myelofibrosis via a frameshift that removes an endoplasmic reticulum retention signal, creating a neoepitope potentially targetable by immunotherapeutic approaches. We developed a specific rat monoclonal IgG2α antibody, 4D7, directed against the common sequence encoded by both insertion and deletion mutations. 4D7 selectively bound to cells co‐expressing mutant CALR and thrombopoietin receptor (TpoR) and blocked JAK‐STAT signalling, TPO‐independent proliferation and megakaryocyte differentiation of mutant CALR myelofibrosis progenitors by disrupting the binding of CALR dimers to TpoR. Importantly, 4D7 inhibited proliferation of patient samples with both insertion and deletion CALR mutations but not JAK2 V617F and prolonged survival in xenografted bone marrow models of mutant CALR‐dependent myeloproliferation. Together, our data demonstrate a novel therapeutic approach to target a problematic disease driven by a recurrent somatic mutation that would normally be considered undruggable.