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Functional Testing to Characterize and Stratify PI3K Inhibitor Responses in Chronic Lymphocytic Leukemia
Yanping Yin1,2,3, Paschalis Athanasiadis4,5, Linda Karlsen1,2
1Department of Cancer Immunology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway.
Purpose:
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.
Experimental Design:
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.
Results:
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.
Conclusions:
Our findings suggest novel treatment vulnerabilities in idelalisib-refractory/intolerant CLL, and indicate that ex vivo functional profiling may stratify PI3Ki responders.
Insights
Researchers explored phosphoinositide 3-kinase inhibitors (PI3Ki) for chronic lymphocytic leukemia (CLL). Functional profiling identified vulnerabilities and potential biomarkers to predict patient response to PI3Ki therapy.
Area of Science:
- Oncology
- Immunology
- Pharmacology
Background:
- Phosphoinositide 3-kinase inhibitors (PI3Ki) are approved for treating chronic lymphocytic leukemia (CLL).
- Treatment intolerance and resistance to PI3Ki present significant clinical challenges in CLL management.
- Predictive biomarkers are crucial for optimizing individual treatment responses to PI3Ki therapies.
Purpose of the Study:
- To characterize the activity and cellular effects of 10 PI3Ki in CLL.
- To identify treatment vulnerabilities in PI3Ki-refractory/intolerant CLL using functional analyses.
- To determine if ex vivo functional profiling can stratify patients who will respond to PI3Ki.
Main Methods:
- Peripheral blood mononuclear cells from 51 treatment-naïve and PI3Ki-treated CLL patients were analyzed.
- Cells were profiled against 10 PI3Ki and venetoclax using flow cytometry for signaling and immune phenotypes.
- Cell viability was assessed via cleaved caspase-3 and CellTiter-Glo assays; drug sensitivities and protein profiling were also performed.
Main Results:
- Pan-PI3Ki demonstrated efficacy in inhibiting PI3K signaling and viability in both treatment-naïve and idelalisib-refractory/intolerant CLL cells.
- Copanlisib, a pan-PI3Ki, inhibited PI3K signaling in B and T cells, unlike idelalisib.
- Combination therapy with PI3Ki and venetoclax synergistically induced apoptosis; drug sensitivity analysis stratified responders.
Conclusions:
- Novel treatment vulnerabilities in idelalisib-refractory/intolerant CLL were identified.
- Ex vivo functional profiling shows promise for stratifying patients likely to respond to PI3Ki.
- These findings support the development of personalized treatment strategies for CLL.
