Comprehensive analysis of T cell leukemia signals reveals heterogeneity in the PI3 kinase-Akt pathway and limitations of PI3 kinase inhibitors as monotherapy

• Published in: PloS one Vol. 13; no. 5; p. e0193849
• Main Authors: Ksionda, Olga, Mues, Marsilius, Wandler, Anica M, Donker, Lisa, Tenhagen, Milou, Jun, Jesse, Ducker, Gregory S, Matlawska-Wasowska, Ksenia, Shannon, Kevin, Shokat, Kevan M, Roose, Jeroen P
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 25.05.2018; Public Library of Science (PLoS)
• Subjects: 1-Phosphatidylinositol 3-kinase; Acute lymphoblastic leukemia; Acute lymphocytic leukemia; AKT protein; Analysis; Animals; Apoptosis; Apoptosis - drug effects; Biology and Life Sciences; Breast cancer; Cancer; Cancer therapies; Cell cycle; Cell death; Cell Proliferation - drug effects; Cellular signal transduction; Chemotherapy; Clinical trials; Cytokines; Cytotoxicity; Drug therapy; Flow cytometry; Gene Expression Regulation, Enzymologic - drug effects; Gene Expression Regulation, Neoplastic - drug effects; Genetic aspects; Genotoxicity; Heterogeneity; Humans; Indazoles - pharmacology; Inhibitors; Isoforms; Kinases; Lesions; Leukemia; Lymphatic leukemia; Lymphocytes; Lymphocytes T; Medical prognosis; Medicine and Health Sciences; Mice; Mice, Inbred C57BL; Molecular chains; Mutation; Pathogenesis; Pediatrics; Phosphatidylinositol 3-Kinases - genetics; Phosphatidylinositol 3-Kinases - metabolism; Phosphoinositide-3 Kinase Inhibitors; Physiological aspects; Precursor T-Cell Lymphoblastic Leukemia-Lymphoma - drug therapy; Precursor T-Cell Lymphoblastic Leukemia-Lymphoma - genetics; Precursor T-Cell Lymphoblastic Leukemia-Lymphoma - metabolism; Precursor T-Cell Lymphoblastic Leukemia-Lymphoma - pathology; Protein Kinase Inhibitors - pharmacology; Proteins; Proto-Oncogene Proteins c-akt - genetics; Proto-Oncogene Proteins c-akt - metabolism; Signal transduction; Signal Transduction - drug effects; Signaling; Sulfonamides - pharmacology; Toxicity; Tumor Cells, Cultured; Xenograft Model Antitumor Assays; United States; San Francisco California; California; United States > US; New Mexico
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0193849

T cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematologic cancer. Poly-chemotherapy with cytotoxic and genotoxic drugs causes substantial toxicity and more specific therapies targeting the underlying molecular lesions are highly desired. Perturbed Ras signaling is prevalent in T-ALL and occurs via oncogenic RAS mutations or through overexpression of the Ras activator RasGRP1 in ~65% of T-ALL patients. Effective small molecule inhibitors for either target do not currently exist. Genetic and biochemical evidence link phosphoinositide 3-kinase (PI3K) signals to T-ALL, PI3Ks are activated by Ras-dependent and Ras-independent mechanisms, and potent PI3K inhibitors exist. Here we performed comprehensive analyses of PI3K-Akt signaling in T-ALL with a focus on class I PI3K. We developed a multiplex, multiparameter flow cytometry platform with pan- and isoform-specific PI3K inhibitors. We find that pan-PI3K and PI3K γ-specific inhibitors effectively block basal and cytokine-induced PI3K-Akt signals. Despite such inhibition, GDC0941 (pan-PI3K) or AS-605240 (PI3Kγ-specific) as single agents did not efficiently induce death in T-ALL cell lines. Combination of GDC0941 with AS-605240, maximally targeting all p110 isoforms, exhibited potent synergistic activity for clonal T-ALL lines in vitro, which motivated us to perform preclinical trials in mice. In contrast to clonal T-ALL lines, we used a T-ALL cancer model that recapitulates the multi-step pathogenesis and inter- and intra-tumoral genetic heterogeneity, a hallmark of advanced human cancers. We found that the combination of GDC0941 with AS-605240 fails in such trials. Our results reveal that PI3K inhibitors are a promising avenue for molecular therapy in T-ALL, but predict the requirement for methods that can resolve biochemical signals in heterogeneous cell populations so that combination therapy can be designed in a rational manner.