T-Cell Acute Lymphoblastic Leukemia Patients with Mutations in IL7Ra or Downstream RAS-MEK or PI3K-AKT Can be Collectively Targeted By Combination of RAS and AKT Inhibitors

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 445-445
Author(s):  
Kirsten Canté-Barrett ◽  
Jill AP Spijkers-Hagelstein ◽  
Jessica GCAM Buijs-Gladdines ◽  
Wilco K Smits ◽  
Rogier C Buijsman ◽  
...  
Keyword(s):  
Acute Lymphoblastic Leukemia ◽  
T Cell ◽  
Translational Research ◽  
Lymphoblastic Leukemia ◽  
Wild Type ◽  
Mtor Inhibition ◽  
Cytotoxic Effects ◽  
Downstream Signaling ◽  
Cell Acute Lymphoblastic Leukemia ◽  
Equity Ownership

Abstract Background: Pediatric T-cell acute lymphoblastic leukemia patients frequently harbor mutations in IL7Ra or downstream molecules encoded by JAK1, JAK3, N-RAS, K-RAS, NF1, AKT, and PTEN. These mutated signaling molecules can contribute to leukemia by disturbing a multitude of cellular processes such as the cell cycle, epigenetics, apoptosis, or affecting other important signal transduction pathways. Aims: We aimed to determine the overall incidence of mutations in IL7Ra and downstream signaling components in a large cohort of pediatric T-ALL patients. In order to find better treatment options for patients with these mutations, we analyzed the effect of selected IL7Ra-pathway inhibitors-individually and in combinations-on downstream signaling and cytotoxicity in Ba/F3 cells expressing each of the mutations. Methods: We sequenced 146 pediatric T-ALL patient samples for mutations in the FERM, pseudokinase and kinase domains of the Janus kinase gene family (JAK1, JAK2, JAK3, TYK2) and hotspot regions of N-RAS and K-RAS. We adapted the IL3-dependent Ba/F3 cell line to express mutant or wild type genes upon induction by doxycycline and assessed cell viability and signaling in the absence of IL3. Various IL7Ra-pathway inhibitors were tested using this system, and the synergy of combined inhibitors was determined by comparing the dose-response curve of different ratios of IC50-based inhibitor concentrations to the curves for each of the single inhibitors. The Combination Index was calculated using Calcusyn™ software. Results: IL7Ra, JAK, RAS, AKT and PTEN mutations are present in approximately 45% of patients and occur in a predominantly mutually exclusive fashion, suggesting they share aberrant activation of similar downstream targets. We found JAK1, JAK3 and RAS mutations as previously reported, but also identified new JAK1 mutations including V427M, L624YPILKV, E668Q, P815S, and T901G. A novel three-dimensional model of JAK1 reveals that mutations in JAK molecules affect important amino acids that are involved in the interaction between the pseudokinase and kinase domains, facilitating constitutive kinase activity. In our doxycycline-inducible IL3-dependent Ba/F3 system, expression of mutant genes-in contrast to the wild type genes-transforms Ba/F3 cells by supporting IL3-independent growth through activation of the RAS-MEK-ERK and PI3K-AKT pathways. We used this system to test the sensitivity to pharmacological inhibitors; IL7Ra and JAK mutant Ba/F3 cells are sensitive to JAK inhibition, so JAK inhibitors such as ruxolitinib may offer therapeutic potential for IL7Ra, JAK1 or most JAK3 mutated T-ALL patients. The RAS and AKT mutants respond to RAS-MEK and PI3K-AKT-mTOR inhibition, respectively, but are-as expected-insensitive to JAK inhibition. Remarkably, IL7Ra and JAK mutants are relatively resistant to downstream RAS-MEK-ERK or PI3K-AKT-mTOR inhibition, indicating that inhibiting just one of these downstream pathways is insufficient. We provide evidence of (cross-)activation of the alternate pathway when one of these pathways is inhibited. Combined inhibition of MEK and PI3K/AKT synergistically prevents proliferation of the IL7Ra- and JAK-mutants by efficiently blocking both downstream signaling pathways. Furthermore, this combined inhibition is cytotoxic in two out of five tested primary T-ALL specimens. Summary/Conclusion: We show that the combined inhibition of MEK and PI3K/AKT leads to strong and synergistic cytotoxic effects in the IL7Ra and JAK mutants and efficiently blocks signaling downstream of both pathways. This inhibitor combination is effective in two out of five primary T-ALL samples. Therefore, the cytotoxic effects of synergistic MEK and PI3K/AKT inhibition should be further explored as a therapeutic option for (relapsed) ALL patients. Disclosures Buijsman: Netherlands Translational Research Center B.V.: Equity Ownership, Other: founder and shareholder. Zaman:Netherlands Translational Research Center B.V.: Equity Ownership, Other: founder and shareholder.

TYK2-STAT1 Pathway Positively Regulates BCL2 Gene Expression in T-Cell Acute Lymphoblastic Leukemia

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 1470-1470
Author(s):  
Takaomi Sanda ◽  
Jeffrey W Tyner ◽  
Alejandro Gutierrez ◽  
Vu N Ngo ◽  
Jason M Glover ◽  
...  
Keyword(s):  
Gene Expression ◽  
Acute Lymphoblastic Leukemia ◽  
T Cell ◽  
Protein Expression ◽  
Cell Lines ◽  
Lymphoblastic Leukemia ◽  
Wild Type ◽  
Cell Acute Lymphoblastic Leukemia ◽  
Bcl2 Protein ◽  
Bcl2 Expression

Abstract Abstract 1470 To discover oncogenic pathways that are characteristically deregulated in T-cell acute lymphoblastic leukemia (T-ALL), we performed RNA interference screens both in T-ALL cell lines and primary specimens. We found that the JAK tyrosine kinase family member, TYK2, and its downstream effector, STAT1, are each required for the survival of T-ALL cells. To identify the effector molecules downstream of the TYK2-STAT1 pathway in T-ALL, we analyzed global gene expression profiles in TYK2-dependent T-ALL cell lines after silencing of TYK2 or STAT1. As expected, gene set enrichment analysis revealed that genes downregulated by TYK2 knockdown were generally also downregulated by knockdown of STAT1. Importantly, we found that expression of the anti-apoptotic gene BCL2 was significantly downregulated after silencing of both TYK2 and STAT1. Analysis by quantitative PCR of additional T-ALL cell lines revealed that silencing of TYK2 resulted in significant reductions of BCL2 mRNA expression in multiple TYK2-dependent cell lines. Expression of the wild-type but not the kinase-dead TYK2 protein was sufficient to rescue BCL2 protein expression and to prevent apoptosis after knockdown of endogenous TYK2, indicating that the tyrosine kinase activity of TYK2 is required for BCL2 upregulation. Similarly, expression of the shRNA-resistant wild-type STAT1A protein partially rescued BCL2 protein expression and prevented apoptosis, while a variant of STAT1A (Y701F) that is incapable of becoming phosphorylated on a requisite tyrosine residue did not rescue BCL2 levels. Taken together, our findings indicate that aberrant activation of a TYK2-STAT1 pathway upregulates BCL2 expression in T-ALL cells, and that the T-ALL cells develop pathway dependence, in that they require these sustained high levels BCL2 expression for survival. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Loss of PTEN in Pediatric T-Cell Acute Lymphoblastic Leukemia Patients: Proteomic and Molecular Characterization

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 2408-2408
Author(s):  
Paola Bonaccorso ◽  
Cristina Bugarin ◽  
Chiara Buracchi ◽  
Grazia Fazio ◽  
Maddalena Paganin ◽  
...  
Keyword(s):  
Acute Lymphoblastic Leukemia ◽  
T Cell ◽  
Protein Extraction ◽  
Conflicts Of Interest ◽  
Lymphoblastic Leukemia ◽  
Strong Association ◽  
Mtor Pathway ◽  
Wild Type ◽  
Pten Protein ◽  
Cell Acute Lymphoblastic Leukemia

Abstract Signaling networks such as the PI3K/Akt/PTEN/mTOR pathway play a role in the modulation of the aggressiveness of T-Cell Acute Lymphoblastic Leukemia (T-ALL), but the significance of an aberrant activation of this pathway is poorly investigated. The master regulator of PI3K-AKT signaling is the lipid phosphatase and tensin homolog (PTEN); decreased or absent PTEN expression or activity could be associated with a constitutive activation of PI3K/Akt/PTEN/mTOR signaling pathway in T-ALLs. We investigated PTEN Exon7 mutations in diagnostic DNA samples from 67 pediatric T-ALL enrolled in AIEOP ALL2000 and R2006 protocols according to methods by Bandapalli et al. (Haematologica, 2012). We also investigated the PI3K/Akt/PTEN/mTOR pathway using Western Blotting (WB) and Flow Cytometry (FC) in parallel. WB analysis was performed using standard RIPA buffer for protein extraction. FC analysis of protein expression was applied as previously described (Gaipa G et al, Leukemia 2008), and protein levels were measured as % of positive cells compared to isotype control. Positivity or negativity by WB was established by presence or absence of a protein band, while for FC a threshold for positivity was set at ≥ 1% of positive cells. PTEN Exon 7 mutations were identified in 11 out of 67 (16.4%) of patients. According to samples availability, PI3K/Akt/PTEN/mTOR pathway was studied in 9 out of 67 patients (3 PTEN Exon 7 mutated and 6 wild type). PTEN protein resulted completely absent in all three PTEN Exon 7 mutated patients, by contrast PTEN was expressed in all 6 PTEN exon 7 wild type patients (mean by FC 46.98% ± 28.58%). This finding was fully confirmed when WB was applied to the same samples. We did not observe any statistically significant differences in p4EBP1 or mTOR levels in Exon 7 mutated patients as compared to wild type. By contrast, PTEN Exon 7 mutated blasts showed lower phospho-S6 levels compared to PTEN Exon7 wild type patients (mean 3.0% of positive cells vs 32.0%, p=ns). In conclusion, our data show a frequency of PTEN Exon 7 mutations of 16.4%, in agreement with the report by Bandapalli et al. (17.3%). Interestingly, we observed a strong association between the PTEN Exon 7 mutation and the total absence of PTEN protein in the pediatric T-ALL patients studied (data not reported so far to our knowledge). Moreover, although the differences are not statistically significant, p-S6 expression resulted consistently lower in mutated patients as compared to wild type patients. If confirmed in a larger cohort of pediatric T-ALLs, our data could open new insights in the significance of PTEN Exon 7 mutation in pediatric T-ALL and its associated functional profile. Disclosures No relevant conflicts of interest to declare.

Activating NOTCH1 Mutations Are Associated with Good Treatment Response in Childhood T-Cell Acute Lymphoblastic Leukemia.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 1444-1444
Author(s):  
Stephen Breit ◽  
Martin Stanulla ◽  
Thomas Flohr ◽  
Martin Schrappe ◽  
Wolf-Dieter Ludwig ◽  
...  
Keyword(s):  
Acute Lymphoblastic Leukemia ◽  
T Cell ◽  
Confidence Interval ◽  
Treatment Response ◽  
Lymphoblastic Leukemia ◽  
Wild Type ◽  
Cell Acute Lymphoblastic Leukemia ◽  
The Impact ◽  
Notch1 Mutations

Abstract T-cell acute lymphoblastic leukemia (T-ALL) accounts for 10–15 % of pediatric ALL. Very rare cases of T-ALL (< 1 %) harbor the chromosomal translocation t(7;9) that involves NOTCH1, a gene encoding a single-pass, heterodimeric transmembrane receptor. NOTCH1 has an essential function in early intrathymic T-cell development. Recently, it has been demonstrated that more than 50 % of childhood T-ALLs carry activating mutations within the NOTCH1 gene (Weng et al., Science 2004). In the present study, we systematically analyzed the impact of activating NOTCH1 mutations on treatment response in 108 pediatric T-ALLs, registered in the ongoing ALL-BFM 2000 trial. In 56 cases (51.8%) activating NOTCH1 mutations were identified, located either in the heterodimerization (38/56 mutations; 65.5%), in the PEST (10/56; 17.9%) or in both domains (8/56; 14.3%). The presence of activating NOTCH1 mutations was significantly correlated with good prednisolone (p = 0.001, c2 or Fisher’s exact test) and MRD response (p = 0.002). T-ALLs with NOTCH1 mutations were 3.7 times more likely to show a good prednisolone response (95% confidence interval = 1.64–8.33; p = 0.002) and 4.8 times more likely to show a favorable MRD response (95% confidence interval = 2.04–11.11; p = 0.0003) when compared to patients with wild type NOTCH1. Patients with mutated NOTCH1 were thus underrepresented in the high risk group of the ALL-BFM 2000 protocol. This influence of NOTCH1 mutational status on risk stratification was independent from other commonly used criteria, like age and initial white blood cell count (WBC) at the time of diagnosis. Considering the impact of NOTCH1 mutations on long term prognosis, we analyzed those 49 patients of this cohort with a median follow-up of > 4 years. Eight patients relapsed within this follow-up period, 2 patients with mutated and 6 with wild type NOTCH1. With this small number of relapses, this trend towards a favorable influence of activating NOTCH1 mutations on EFS did not reach statistical significance. In conclusion, T-ALLs with NOTCH1 mutations are demonstrated to be more sensitive than those without to the ALL-BFM 2000 treatment strategy and may show a lower rate of relapse.

scholarly journals Overexpression of wild type IL-7Rα promotes T-cell acute lymphoblastic leukemia/lymphoma

Blood ◽  
2021 ◽  
Author(s):  
Ana Patricia Silva ◽  
Afonso R.M. Almeida ◽  
Ana Cachucho ◽  
João L Neto ◽  
Sofie Demeyer ◽  
...  
Keyword(s):  
Acute Lymphoblastic Leukemia ◽  
T Cell ◽  
Lymphoblastic Leukemia ◽  
Mrna Levels ◽  
Wild Type ◽  
Transcriptional Signature ◽  
Cell Acute Lymphoblastic Leukemia ◽  
Signaling Activation ◽  
Mutational Activation ◽  
The Impact

Tight regulation of IL-7Rα expression is essential for normal T-cell development. IL-7Rα gain-of-function mutations are known drivers of T-cell acute lymphoblastic leukemia (T-ALL). Although a subset of T-ALL patients display very high IL7R mRNA levels and cases with IL7R gains have been reported, the impact of IL-7Rα overexpression, rather than mutational activation, on leukemogenesis remains unclear. Here, we show that overexpression of IL-7Rα in tetracycline-inducible Il7r transgenic and Rosa26 IL7R knock-in mice drives potential thymocyte self-renewal, and thymus hyperplasia due to increased proliferation of T-cell precursors, which subsequently infiltrate lymph nodes, spleen and bone marrow, ultimately leading to fatal leukemia. The tumors mimic key features of human T-ALL, including heterogeneity in immunophenotype and genetic subtype between cases, frequent hyperactivation of PI3K/Akt pathway that is paralleled by downregulation of p27Kip1 and upregulation of Bcl-2, and gene expression signatures evidencing JAK/STAT, PI3K/Akt/mTOR and Notch signaling activation. Notably, we also find that established tumors may no longer require high levels of IL-7R expression upon secondary transplantation and can progress in the absence of IL-7, but remain sensitive to inhibitors of IL-7R-mediated signaling Ruxolitinib (Jak1), AZD1208 (Pim), Dactolisib (PI3K/mTOR), Palbociclib (Cdk4/6), and Venetoclax (Bcl-2). The relevance of these findings for human disease are highlighted by the fact that T-ALL patient samples with high wild type IL7R expression display a transcriptional signature resembling that from IL-7-stimulated pro-T cells and, critically, from IL7R mutant T-ALL cases. Overall, our studies demonstrate that high expression of IL-7Rα can promote T-cell tumorigenesis even in the absence of IL-7Rα mutational activation.

3D Modeling of Novel Transforming JAK Mutations in T-Cell Acute Lymphoblastic Leukemia Reveals Altered Pseudokinase-Kinase Domain Interactions That Result in Constitutive JAK Kinase Activity

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 869-869
Author(s):  
Kirsten Canté-Barrett ◽  
Joost CM Uitdehaag ◽  
Jessica GCAM Buijs-Gladdines ◽  
Wilco K Smits ◽  
Rogier C Buijsman ◽  
...  
Keyword(s):  
Acute Lymphoblastic Leukemia ◽  
3D Model ◽  
Kinase Activity ◽  
Lymphoblastic Leukemia ◽  
Kinase Domain ◽  
Salt Bridges ◽  
Wild Type ◽  
Jak Kinase ◽  
Cell Acute Lymphoblastic Leukemia ◽  
Equity Ownership

Abstract Background: Many pediatric T-cell acute lymphoblastic leukemia patients harbor mutations in IL7Ra or downstream molecules encoded by JAK1, JAK3, N-RAS, K-RAS, NF1, AKT, and PTEN. These mutated signaling molecules can contribute to leukemia by disturbing a multitude of cellular processes such as the cell cycle, epigenetics, apoptosis, or affecting other important signal transduction pathways. Aims: We aimed to determine the overall incidence of JAK family mutations in a large cohort of T-ALL patients. We also aimed to generate a 3D JAK1 model including known and newly identified JAK mutations in order to better understand how these contribute to JAK kinase activity and the transformation of cells. Methods: We screened 146 pediatric T-ALL patient samples for mutations in the FERM, pseudokinase and kinase domains of the Janus kinase gene family (JAK1-3, TYK2). To establish a 3D JAK1 model, we superimposed individual pseudokinase and kinase crystallographic structures on the homologous TYK2 pseudokinase-kinase structure. We visualized JAK mutations and their effects on the 3D structure. We modified the IL3-dependent Ba/F3 cell line to express JAK mutant or wild type genes upon induction by doxycycline. We tested these Ba/F3 derivative lines for transforming ability, signaling, and resistance to various inhibitors in the absence of IL3. Results: JAK1 or JAK3 mutations were found in 10 patients; no mutations were found in JAK2 or TYK2. We found JAK1 and JAK3 mutations as previously reported, but also identified amino acid substitutions as a result of novel JAK1 mutations including V427M, L624YPILKV, E668Q, P815S, and T901G. Our novel 3D model of JAK1 places most mutations in one of two crucial pseudokinase-kinase interaction sites, which can weaken the interaction and facilitate constitutive kinase activity. One interaction is between the hinge region of the pseudokinase domain and the loop in the kinase domain, which is supported by four salt bridges. Mutations in T-ALL disrupting these salt bridges include E668Q, R724H and its JAK3 equivalent R657Q, and T901G. The second interaction with the kinase domain is formed by a helical domain in the pseudokinase domain, located just upstream of the conserved F575-F636-V658 triad. This F-F-V triad is predicted to act as a structural switch that controls the catalytic activity of JAK kinases. Various mutations occur in the direct vicinity and can affect the function of this switch. V658F in T-ALL and its JAK2 equivalent V617F in polycythemia vera patients are mutations in this triad. The frequent JAK3 mutation M511I in T-ALL flanks the F513 residue (equivalent of JAK1 F575) and also affects the F-F-V triad. The L624YPILKV insertion mutation is located in a loop near the helical domain, which may also subtly compromise the F-F-V triad structural switch leading to derepression of the kinase domain. Expression of mutant JAK genes-in contrast to the wild type genes-transforms Ba/F3 cells by supporting IL3-independent growth, and by activating downstream RAS-MEK-ERK and PI3K-AKT pathways. This pathway activation as a result of ligand-independent mutant JAK kinase activity was confirmed by measuring phospho-proteins including p-MEK, p-ERK, p-AKT, p-mTOR, and p-p70S6K, and can be blocked by JAK inhibitors. Notably, JAK3 mutants signal significantly weaker than JAK1 mutants, possibly due to different dependence on (endogenous) receptors that normally mediate wild type JAK signaling. Summary/Conclusion: In a 3D model, we show that JAK mutations are located in critical interface regions between the pseudokinase and kinase domains, maintaining the kinase in an open, active confirmation. The inducible Ba/F3 model system confirms the transforming capacity of JAK mutations, reveals constitutive active downstream signaling, and is also suitable to test the effect of various inhibitors. The visualization of various JAK mutations in a 3D model and how these contribute to kinase activity provides insight in how mutant JAK could be inhibited, helping guide the development of new small molecule inhibitors of mutant JAKs. Disclosures Buijsman: Netherlands Translational Research Center B.V.: Equity Ownership, Other: founder and shareholder. Zaman:Netherlands Translational Research Center B.V.: Equity Ownership, Other: founder and shareholder.

scholarly journals JAK/STAT Pathway Inhibition Reverts IL7-Induced Glucocorticoid Resistance in a Subset of Human T-Cell Acute Lymphoblastic Leukemia

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 3963-3963
Author(s):  
Cristina Delgado-Martin ◽  
Kristin Shimano ◽  
Matthew S Zinter ◽  
Justin T. Wahlstrom ◽  
Geoffrey A. Smith ◽  
...  
Keyword(s):  
Acute Lymphoblastic Leukemia ◽  
T Cell ◽  
Research Funding ◽  
Lymphoblastic Leukemia ◽  
Vitro Assay ◽  
Laboratory Services ◽  
Cell Acute Lymphoblastic Leukemia ◽  
Equity Ownership ◽  
Pathway Inhibition ◽  
Stat Pathway

Abstract Although outcomes for patients with T-cell acute lymphoblastic leukemia (T-ALL) have improved dramatically, survival rates for relapsed or refractory T-ALL remain less than 10%. While mechanisms mediating chemotherapy resistance in these patients remain incompletely understood, resistance to glucocorticoids (GC), a central component of therapy, may be particularly important. GC resistance occurs more commonly than resistance to other chemotherapeutic agents in ALL. Additionally, newly diagnosed patients that fail to rapidly clear their peripheral leukemic blasts during an upfront window of prednisone (prednisone poor response) have a poorer outcome, suggesting differences in GC sensitivity may exist at diagnosis. Here, we develop an in vitro assay to model the early prednisone response. Using primary, pre-treatment human T-ALL samples, we demonstrate that individual T-ALLs have distinct intrinsic GC sensitivity thresholds at diagnosis and that this threshold can predict end induction MRD. To interrogate potential mechanisms of GC resistance, we use a panel of patient-derived xenografts (PDX) generated from diagnostic T-ALLs. We find that intrinsic GC resistance is uniformly seen in T-ALLs that arise at the early thymic progenitor (ETP) stage as well as in a subset of non-ETP T-ALLs. Removal of IL7 from the media or inhibition of IL7/JAK/STAT signaling with the JAK1/2 inhibitor ruxolitinib or a novel JAK3 inhibitor, JAK3i, reverses GC resistance in ETP and a subset of the non-ETP T-ALL. This effect is drug specific, since IL7 does not offer protection from death induced by other agents. IL7-dependent GC resistance can be predicted by hyper-responsiveness to IL7 stimulation. Mechanistically, the combination of dexamethasone and ruxolitinib alters the balance between BCL2 and BIM in IL7-dependent, but not IL7-independent, GC resistant T-ALL samples. Together, these data support a model where IL7, a cytokine with leukemogenic properties that is normally present in lymphopoietic niches, contributes to intrinsic GC resistance in a subset of T-ALL samples. This environmentally induced GC resistance may be reversed with IL7/JAK/STAT pathway inhibition. This could result in an augmented leukemotoxic effect of GC treatment, potentially enhancing efficacy of glucocorticoids in a subset of patients and justifying exposure to the toxic side effects of GCs. Disclosures Taunton: Global Blood Therapeutics: Equity Ownership; Kezar Life Sciences: Equity Ownership, Research Funding; Pfizer: Research Funding; Principia Biopharma: Consultancy, Equity Ownership; Circle Pharma: Consultancy, Equity Ownership; Cell Design Labs: Consultancy, Equity Ownership. Wood:Juno: Other: Laboratory Services Agreement; Amgen: Honoraria, Other: Laboratory Services Agreement; Pfizer: Honoraria, Other: Laboratory Services Agreement; Seattle Genetics: Honoraria, Other: Laboratory Services Agreement. Teachey:Novartis: Research Funding.

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