Ultraprecision therapy for type 1 vs type 2 CALR+ MPN by dual epitope targeting that restores ruxolitinib sensitivity
Abstract
Abstract Somatic frameshift mutations in the gene encoding calreticulin (CALR) give rise to myelofibrosis and are classified as type 1 (del52) or type 2 (ins5) according to the degree of wild-type sequence retained adjacent to the neopeptide, with each type conferring different clinical outcomes. Targeting strategies specific for type 1 vs type 2 mutations would have enormous clinical utility in the treatment and prevention of myelofibrosis as responses to tyrosine kinase inhibitors are not durable nor mutation specific. Here, we show that dual targeting of type 1 (del52) mutant CALR with 2 monoclonal antibodies directed against distinct epitopes in CALR have significant advantages compared with single-agent treatment in the eradication of primary megakaryocyte progenitors in vitro and in a humanized ossicle microenvironment leading to improved survival in xenograft models. Dual targeting was superior in blocking constitutive STAT5 and extracellular signal-regulated kinase phosphorylation induced by del52 and prevented accumulation of Janus kinase 2 (JAK2) phosphorylation, overcoming ruxolitinib resistance. In contrast, type 2 mutations showed increased CALR dimerization and were partially resistant to antibody targeting but could be affected by a ruxolitinib triple combination. Together, our data demonstrate an ultraprecision medicine approach tailored to either type 1 or type 2 mutation classes will be required for maximal efficacy and complete blockade of JAK/STAT signaling, with far-reaching implications for patient management.
Article Details
Authors (24)
Chloe A. L. Thompson-Peach
1Cancer Program, Precision Medicine Theme, South Australian Health and Medical Research Institute, and School of Medicine, College of Health, Adelaide University, Adelaide, Australia
Daniel Thomas
School of Medicine, College of Health, Adelaide University
Mara Dottore
2Division of Human Immunology SA Pathology, and Centre for Cancer Biology, Adelaide University, Adelaide, Australia
Kelly Lim
Frank Stomski
2Division of Human Immunology SA Pathology, and Centre for Cancer Biology, Adelaide University, Adelaide, Australia
Romana A. Panagopoulos
1Cancer Program, Precision Medicine Theme, South Australian Health and Medical Research Institute, and School of Medicine, College of Health, Adelaide University, Adelaide, Australia
Johannes Foßelteder
3Division of Hematology, Department of Internal Medicine, Medical University of Graz, Graz, Austria
Andreas Reinisch
3Division of Hematology, Department of Internal Medicine, Medical University of Graz, Graz, Austria
Vashe Chandrakanthan
1Cancer Program, Precision Medicine Theme, South Australian Health and Medical Research Institute, and School of Medicine, College of Health, Adelaide University, Adelaide, Australia
Sandra Jenkner
1Cancer Program, Precision Medicine Theme, South Australian Health and Medical Research Institute, and School of Medicine, College of Health, Adelaide University, Adelaide, Australia
Luke Bland
1Cancer Program, Precision Medicine Theme, South Australian Health and Medical Research Institute, and School of Medicine, College of Health, Adelaide University, Adelaide, Australia
Sharon Paton
1Cancer Program, Precision Medicine Theme, South Australian Health and Medical Research Institute, and School of Medicine, College of Health, Adelaide University, Adelaide, Australia
Stan Gronthos
1Cancer Program, Precision Medicine Theme, South Australian Health and Medical Research Institute, and School of Medicine, College of Health, Adelaide University, Adelaide, Australia
Timothy R. Hercus
2Division of Human Immunology SA Pathology, and Centre for Cancer Biology, Adelaide University, Adelaide, Australia
Hannah R. Wardill
1Cancer Program, Precision Medicine Theme, South Australian Health and Medical Research Institute, and School of Medicine, College of Health, Adelaide University, Adelaide, Australia
Winnie L. Kan
2Division of Human Immunology SA Pathology, and Centre for Cancer Biology, Adelaide University, Adelaide, Australia
Maha M. Kamel
1Cancer Program, Precision Medicine Theme, South Australian Health and Medical Research Institute, and School of Medicine, College of Health, Adelaide University, Adelaide, Australia
Paul A. Moretti
2Division of Human Immunology SA Pathology, and Centre for Cancer Biology, Adelaide University, Adelaide, Australia
Stuart M. Pitson
Centre for Cancer Biology, College of Health, Adelaide University and SA Pathology
Kate Burbury
4Department of Clinical Haematology, Peter MacCallum Cancer Centre, The University of Melbourne, Melbourne, Australia
David M. Ross
21Haematology Directorate, SA Pathology, Royal Adelaide Hospital and Flinders Medical Centre, Adelaide, Australia
Pramod C. Nair
1Cancer Program, Precision Medicine Theme, South Australian Health and Medical Research Institute, and School of Medicine, College of Health, Adelaide University, Adelaide, Australia
Angel F. Lopez
2Division of Human Immunology SA Pathology, and Centre for Cancer Biology, Adelaide University, Adelaide, Australia
Denis Tvorogov
2Division of Human Immunology SA Pathology, and Centre for Cancer Biology, Adelaide University, Adelaide, Australia