Supplementary Figure from Functional Testing to Characterize and Stratify PI3K Inhibitor Responses in Chronic Lymphocytic Leukemia
Funding
Research Council of Norway
Centre for Digital Life Norway (DLN)
Regional Health Authority for South Eastern Norway
Stiftelsen Kristian Gerhard Jebsen (KGJF)
Kreftforeningen (NCS)
Lilly Constance og Karl Ingolf Larssons stiftelse
Medical Student Research Program at the University of Oslo
Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung (SNF)
National Cancer Institute (NCI)
United States Department of Health and Human Services
Find out more...Helse Sør-Øst RHF (sorost)
Radiumhospitalets Forskningsstifltelse (RadForsk)
Syöpäsäätiö (Cancerstiftelsen)
Academy of Finland (AKA)
HORIZON EUROPE Framework Programme (Horizon Europe)
ARTICLE ABSTRACT
PI3K inhibitors (PI3Ki) are approved for relapsed chronic lymphocytic leukemia (CLL). Although patients may show an initial response to these therapies, development of treatment intolerance or resistance remain clinical challenges. To overcome these, prediction of individual treatment responses based on actionable biomarkers is needed. Here, we characterized the activity and cellular effects of 10 PI3Ki and investigated whether functional analyses can identify treatment vulnerabilities in PI3Ki-refractory/intolerant CLL and stratify responders to PI3Ki.
Peripheral blood mononuclear cell samples (n = 51 in total) from treatment-naïve and PI3Ki-treated patients with CLL were studied. Cells were profiled against 10 PI3Ki and the Bcl-2 antagonist venetoclax. Cell signaling and immune phenotypes were analyzed by flow cytometry. Cell viability was monitored by detection of cleaved caspase-3 and the CellTiter-Glo assay.
pan-PI3Kis were most effective at inhibiting PI3K signaling and cell viability, and showed activity in CLL cells from both treatment-naïve and idelalisib-refractory/intolerant patients. CLL cells from idelalisib-refractory/intolerant patients showed overall reduced protein phosphorylation levels. The pan-PI3Ki copanlisib, but not the p110δ inhibitor idelalisib, inhibited PI3K signaling in CD4+ and CD8+ T cells in addition to CD19+ B cells, but did not significantly affect T-cell numbers. Combination treatment with a PI3Ki and venetoclax resulted in synergistic induction of apoptosis. Analysis of drug sensitivities to 73 drug combinations and profiling of 31 proteins stratified responders to idelalisib and umbralisib, respectively.
Our findings suggest novel treatment vulnerabilities in idelalisib-refractory/intolerant CLL, and indicate that ex vivo functional profiling may stratify PI3Ki responders.
