Page 194 - Haematologica March 2020

Ferrata Storti Foundation
Haematologica 2020 Volume 105(3):708-720
Acute Myeloid Leukemia
Phenotype-based drug screening reveals association between venetoclax response and differentiation stage in acute myeloid leukemia
Heikki Kuusanmäki,1,2 Aino-Maija Leppä,1 Petri Pölönen,3 Mika Kontro,2
Olli Dufva,2 Debashish Deb,1 Bhagwan Yadav,2 Oscar Brück,2 Ashwini Kumar,1 Hele Everaus,4 Bjørn T. Gjertsen,5 Merja Heinäniemi,3 Kimmo Porkka,2
Satu Mustjoki2,6 and Caroline A. Heckman1
1Institute for Molecular Medicine Finland, Helsinki Institute of Life Science, University of Helsinki, Helsinki; 2Hematology Research Unit, Helsinki University Hospital Comprehensive Cancer Center, Helsinki; 3Institute of Biomedicine, School of Medicine, University of Eastern Finland, Kuopio, Finland; 4Department of Hematology and Oncology, University of Tartu, Tartu, Estonia; 5Centre for Cancer Biomarkers, Department of Clinical Science, University of Bergen, Bergen, Norway and 6Translational Immunology Research Program and Department of Clinical Chemistry and Hematology, University of Helsinki, Helsinki, Finland
ABSTRACT
Ex vivo drug testing is a promising approach to identify novel treatment strategies for acute myeloid leukemia (AML). However, accurate blast- specific drug responses cannot be measured with homogeneous “add- mix-measure” cell viability assays. In this study, we implemented a flow cytometry-based approach to simultaneously evaluate the ex vivo sensitivity of different cell populations in 34 primary AML samples to seven drugs and 27 rational drug combinations. Our data demonstrate that different cell populations present in AML samples have distinct sensitivity to targeted therapies. Particularly, blast cells of FAB M0/1 AML showed high sensitivity to venetoclax. In contrast, differentiated monocytic cells abundantly pres- ent in M4/5 subtypes showed resistance to Bcl-2 inhibition, whereas imma- ture blasts in the same samples were sensitive, highlighting the importance of blast-specific readouts. Accordingly, in the total mononuclear cell frac- tion the highest BCL2/MCL1 gene expression ratio was observed in M0/1 and the lowest in M4/5 AML. Of the seven tested drugs, venetoclax had the highest blast-specific toxicity, and combining venetoclax with either MEK inhibitor trametinib or JAK inhibitor ruxolitinib effectively targeted all venetoclax-resistant blasts. In conclusion, we show that ex vivo efficacy of targeted agents and particularly Bcl-2 inhibitor venetoclax is influenced by the cell type, and accurate blast-specific drug responses can be assessed with a flow cytometry-based approach.
Introduction
The treatment of AML with high-dose cytarabine and anthracycline-based inten- sive chemotherapy has remained the standard of care for the last four decades.1 Despite the increase in overall survival, only 35 to 40% of adult patients under 60 years are cured with chemotherapy and allogeneic stem cell transplantation.2 A number of novel targeted agents have been investigated in AML, but have usually generated clinical responses only in small patient subsets. Currently, genetic profil- ing is used for patient stratification and determination of treatment, evident by the recent approvals of midostaurin/gilteritinib and ivosidenib/enasidenib for treating AML patients with FLT3 or IDH1/IDH2 mutations, respectively.3–5 Furthermore, the Bcl-2 inhibitor venetoclax combined with a hypomethylating agent has recently been approved for AML with increased efficacy in patients with IDH1/2 and NPM1 mutations.6,7 However, the majority of AML patients lack actionable mutations and our understanding of the relationship between the cancer genotype, phenotype and drug function remains limited. Ex vivo drug testing with primary patient samples
Correspondence:
CAROLINE A. HECKMAN
caroline.heckman@helsinki.fi/
HEIKKI KUUSANMÄKI
heikki.kuusanmaki@helsinki.fi
Received: December 17, 2018. Accepted: July 8, 2019. Pre-published: July 11, 2019.
doi:10.3324/haematol.2018.214882
Check the online version for the most updated information on this article, online supplements, and information on authorship & disclosures: www.haematologica.org/content/105/3/708
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