Metabolomics,Unknown,Transcriptomics,Genomics,Proteomics

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Complete hematologic response of early-T-cell progenitor acute lymphoblastic leukemia to the gamma-secretase inhibitor BMS-906024: genetic and epigenetic findings in an outlier case

ABSTRACT: Notch pathway antagonists such as gamma-secretase inhibitors (GSI) are being tested in diverse cancers, but exceptional responses have yet to be reported. We describe the case of a patient with relapsed/refractory early-T-cell progenitor acute lymphoblastic leukemia (ETP-ALL) who achieved a complete hematologic response following treatment with the GSI BMS-906024. Whole exome sequencing of leukemic blasts revealed heterozygous gain-of-function driver mutations in NOTCH1, CSF3R, and PTPN11, and a homozygous/hemizygous loss-of-function mutation in DNMT3A. The three gain-of-function mutations were absent from remission marrow cells, but the DNMT3A mutation persisted in heterozygous form in remission marrow, consistent with an origin for the patient’s ETP-ALL from clonal hematopoiesis. Ex vivo culture of ETP-ALL blasts confirmed high levels of activated NOTCH1 that were repressed by GSI treatment, and RNA-Seq documented that GSI downregulated multiple known Notch target genes. Surprisingly, one potential target gene that was unaffected by GSI was MYC, a key Notch target in GSI-sensitive T-ALL of cortical T cell type. H3K27ac superenhancer landscapes near MYC showed a pattern previously reported in acute myeloid leukemia (AML) that is sensitive to BRD4 inhibitors, and in line with this ETP-ALL blasts downregulated MYC in response to the BRD4 inhibitor JQ1. To our knowledge, this is the first example of complete response of a Notch-mutated ETP-ALL to a Notch antagonist and is also the first description of chromatin landscapes associated with ETP-ALL. Our experience suggests that additional attempts to target Notch in Notch-mutated ETP-ALL are merited. RNAseq and H3K27Ac ChIP seq of primary leukemic blasts treated in vitro with vehicle control or gamma-secretase inhibitor BMS-096024

ORGANISM(S): Homo sapiens

SUBMITTER: Eric Severson

PROVIDER: E-GEOD-71414 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:The NOTCH signaling cascade, which is deregulated in T-cell acute lymphoblastic leukemia (T-ALL) and many other human cancers, offers an attractive target for molecular therapy. One approach employs gamma-secretase inhibitors (GSIs) to suppress production of the intracellular form of NOTCH (NICD), leading to cell growth arrest and apoptosis. Here we show that missense mutations or homozygous deletion of FBW7, which encodes a ubiquitin ligase that targets the NICD for destruction, mediate constitutive NICD expression. FBW7 mutations target key arginine residues needed for binding to the NICD. Although the mutant forms of Fbw7 still bind to MYC, they do not target MYC for degradation, suggesting that stabilization of both NICD and MYC may contribute to transformation in leukemias with mutations in FBW7. Leukemias with FBW7 mutations are resistant to the growth suppressive and apoptotic effects of the MRK-003 GSI. In some resistant lines that express the NICD, this resistance is accompanied by sustained mRNA levels of the NOTCH target DELTEX1 as well as MYC mRNA and protein, implying that residual NICD activity due to the mutant FBW7 can contribute to GSI resistance. Keywords: T-ALL, gamma-secretase, GSI, cell line comparison, FBW7 mutation Total RNA isolated from cultured cells was used to make fluorescently labeled cRNA that was hybridized to DNA oligonucleotide. Briefly, 4 Âµg of total RNA was used to synthesize dsDNA through reverse transcription. cRNA was produced by in vitro transcription and labeled postsynthetically with Cy3 or Cy5. Two populations of labeled cRNA, a reference population and an experimental population, were compared with each other by competitive hybridization to microarrays. Two hybridizations were done with each cRNA sample pair using a fluorescent dye reversal strategy. Human microarrays contained oligonucleotide probes corresponding to approximately 21,000 genes. All oligonucleotide probes on the microarrays were synthesized in situ with inkjet technology (Agilent Technologies, Palo Alto, CA). After hybridization, arrays were scanned and fluorescence intensities for each probe were recorded. Ratios of transcript abundance (experimental to control) were obtained following normalization and correction of the array intensity data. Gene expression data analysis was done with the Rosetta Resolver gene expression analysis software (version 6.0, Rosetta Biosoftware, Seattle, WA).

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Complete hematologic response of early-T-cell progenitor acute lymphoblastic leukemia to the gamma-secretase inhibitor BMS-906024: genetic and epigenetic findings in an outlier case

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