Targeted therapies against the BCR-ABL1 kinase have revolutionized treatment of chronic phase (CP) chronic myeloid leukemia (CML). In contrast, management of blast crisis (BC) CML remains challenging ...because BC cells acquire complex molecular alterations that confer stemness features to progenitor populations and resistance to BCR-ABL1 tyrosine kinase inhibitors. Comprehensive models of BC transformation have proved elusive because of the rarity and genetic heterogeneity of BC, but are important for developing biomarkers predicting BC progression and effective therapies. To better understand BC, we performed an integrated multiomics analysis of 74 CP and BC samples using whole-genome and exome sequencing, transcriptome and methylome profiling, and chromatin immunoprecipitation followed by high-throughput sequencing. Employing pathway-based analysis, we found the BC genome was significantly enriched for mutations affecting components of the polycomb repressive complex (PRC) pathway. While transcriptomically, BC progenitors were enriched and depleted for PRC1- and PRC2-related gene sets respectively. By integrating our data sets, we determined that BC progenitors undergo PRC-driven epigenetic reprogramming toward a convergent transcriptomic state. Specifically, PRC2 directs BC DNA hypermethylation, which in turn silences key genes involved in myeloid differentiation and tumor suppressor function via so-called epigenetic switching, whereas PRC1 represses an overlapping and distinct set of genes, including novel BC tumor suppressors. On the basis of these observations, we developed an integrated model of BC that facilitated the identification of combinatorial therapies capable of reversing BC reprogramming (decitabine+PRC1 inhibitors), novel PRC-silenced tumor suppressor genes (NR4A2), and gene expression signatures predictive of disease progression and drug resistance in CP.
•Genetically heterogeneous BC progenitors demonstrate molecular convergence on PRC1- and PRC2-regulated pathways.•A model of PRC-driven reprogramming identifies novel BC combination therapies, tumor suppressor genes, and biomarkers for transformation.
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Somatic mutations of TP53 are among the most common in cancer and germline mutations of TP53 (usually missense) can cause Li-Fraumeni syndrome (LFS). Recently, recurrent genomic rearrangements in ...intron 1 of TP53 have been described in osteosarcoma (OS), a highly malignant neoplasm of bone belonging to the spectrum of LFS tumors. Using whole-genome sequencing of OS, we found features of TP53 intron 1 rearrangements suggesting a unique mechanism correlated with transcription. Screening of 288 OS and 1,090 tumors of other types revealed evidence for TP53 rearrangements in 46 (16%) OS, while none were detected in other tumor types, indicating this rearrangement to be highly specific to OS. We revisited a four-generation LFS family where no TP53 mutation had been identified and found a 445 kb inversion spanning from the TP53 intron 1 towards the centromere. The inversion segregated with tumors in the LFS family. Cancers in this family had loss of heterozygosity, retaining the rearranged allele and resulting in TP53 expression loss. In conclusion, intron 1 rearrangements cause p53-driven malignancies by both germline and somatic mechanisms and provide an important mechanism of TP53 inactivation in LFS, which might in part explain the diagnostic gap of formerly classified "TP53 wild-type" LFS.
Some health websites provide a public forum for consumers to post ratings and reviews on drugs. Drug reviews are easily accessible and comprehensible, unlike clinical trials and published literature. ...Because the public increasingly uses the Internet as a source of medical information, it is important to know whether such information is reliable.
We aim to examine whether Web-based consumer drug ratings and reviews can be used as a resource to compare drug performance.
We analyzed 103,411 consumer-generated reviews on 615 drugs used to treat 249 disease conditions from the health website WebMD. Statistical analysis identified 427 drug pairs from 24 conditions for which two drugs treating the same condition had significantly and substantially different satisfaction ratings (with at least a half-point difference between Web-based ratings and P<.01). PubMed and Google Scholar were searched for publications that were assessed for concordance with findings online.
Scientific literature was found for 77 out of the 427 drug pairs and compared to findings online. Nearly two-thirds (48/77, 62%) of the online drug trends with at least a half-point difference in online ratings were supported by published literature (P=.02). For a 1-point online rating difference, the concordance rate increased to 68% (15/22) (P=.07). The discrepancies between scientific literature and findings online were further examined to obtain more insights into the usability of Web-based consumer-generated reviews. We discovered that (1) drugs with FDA black box warnings or used off-label were rated poorly in Web-based reviews, (2) drugs with addictive properties were rated higher than their counterparts in Web-based reviews, and (3) second-line or alternative drugs were rated higher. In addition, Web-based ratings indicated drug delivery problems. If FDA black box warning labels are used to resolve disagreements between publications and online trends, the concordance rate increases to 71% (55/77) (P<.001) for a half-point rating difference and 82% (18/22) for a 1-point rating difference (P=.002). Our results suggest that Web-based reviews can be used to inform patients' drug choices, with certain caveats.
Web-based reviews can be viewed as an orthogonal source of information for consumers, physicians, and drug manufacturers to assess the performance of a drug. However, one should be cautious to rely solely on consumer reviews as ratings can be strongly influenced by the consumer experience.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Current models of CML blast crisis (BC) propose that expression of BCR-ABL results in genomic instability and the acquisition of genetic alterations that affect cell proliferation and survival, ...self-renewal and differentiation. To characterize the molecular events that underlie progression, we performed whole genome sequencing of paired samples of the same patient at CP and at BC (n = 12), as well as expression and methylation arrays of these samples and a larger validation cohort of unpaired CD34-selected samples (n = 38). Contrary to expectations, we found that the CML BC genome is relatively quiescent with regards to SNVs, indels and structural variations. In contrast, we observed widespread hyper-methylation in BC that was associated with distinct changes in expression and was independent of lineage/differentiation state. These findings suggest that in addition to genetic alterations, epigenomic events are likely to contribute substantively to BC progression.
To understand the functional effects of the dysregulated transcriptome and epigenome in BC CML, we employed both pharmacologic and genetic methods to target candidate genes of interest identified in our earlier studies.
To induce de-methylation of the BC genome, we treated primary samples with low doses of decitabine, a DNMT inhibitor. We found that decitabine impaired colony formation ability of BC CD34+ progenitors and concomitantly activated regulators of myeloid differentiation that were both hyper-methylated and down-regulated in BC CD34+ progenitors, such as MPO and KLF1. These results suggest that hyper-methylation does contribute to BC CD34+ progenitor function, and support the use of epigenetic therapies as a rational approach to targeting BC.
The genetic approach we chose was a CRISPR-based in vitro pooled screen. We created a custom library targeting 200 genes, with an average of 5 sgRNAs per gene, and 50 non-targeting controls. We transduced K562 with the library and harvested samples at different time-points post-transduction/selection - Day 0, 7 and 21 - for deep sequencing. As expected, sgRNAs targeting essential genes such as MYC and MCM 2-7 were recurrently depleted in the population over time. More importantly, enriched sgRNAs targeted genes including TET2, which has been previously reported to be inactivated in myeloid malignancies, as well as novel candidates including RREB1, a transcription factor that binds to RAS-responsive elements (RREs) and may be involved in MAPK signaling. We will validate these targets by knocking them out individually and assessing their effect on the ability of CP cells to serially replate and/or engraft immune-deficient mice.
Chuah:Bristol-Myers Squibb: Honoraria; Novartis: Honoraria; Chiltern International: Honoraria. Takahashi:Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; BMS: Honoraria, Research Funding, Speakers Bureau; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Masis: Consultancy; Otsuka: Membership on an entity's Board of Directors or advisory committees; Celgene: Speakers Bureau; Sysmex: Research Funding, Speakers Bureau; Astellas: Speakers Bureau. Valent:Novartis: Consultancy, Honoraria, Research Funding; Ariad: Honoraria, Research Funding; Bristol-Myers Squibb: Honoraria; Pfizer: Honoraria; Celgene: Honoraria.
The transition from chronic phase (CP) to blast crisis (BC) chronic myeloid leukemia (CML) is characterized by reprogramming of the CML transcriptome (Radich et al. PNAS 2006), and shortened ...survival. Current models propose genomic instability as causal in BC transformation with enhanced DNA damage and impaired DNA repair inducing genetic mutations (ranging from large chromosomal aberrations to point mutations), altered gene function, and eventually BC transformation (Perrotti et al. JCI 2010). Consistent with this model are the phenomena of BC clonal evolution, and the increased frequency of ABL kinase domain mutations found in BC. Because different mutational processes are associated with distinct cancer-specific mutation signatures (Alexandrov et al. Nature 2013), this model also predicts the existence of a CML-specific mutation signature. In addition, recent work has highlighted the importance of epigenetic alterations in hematologic malignancies (Shih et al., Nat. Rev. Cancer, 2012). However, we lack a complete understanding of the type or frequency of genetic alterations in BC, and the relative contribution of genetic vs. epigenetic events in reprogramming the BC transcriptome.
To address these knowledge gaps, we analyzed the CML progression genome, epigenome, and transcriptome in 12 CP/BC sample pairs. Whole-genome sequencing revealed the CML genome to be relatively stable with respect to structural variations, indels, and somatic single nucleotide variants. The average number of nonsynonymous coding mutations per BC genome was 5, placing the BC coding genome in the same mutation frequency range as AML and ALL genomes (Alexandrov et al. Nature 2013). In addition, we identified a novel mutation signature in all CML samples suggesting a CML-specific mutational process. 1175 genes were 'hit' by genomic, mostly copy number, alterations in >1 sample, and included TCR genes and Ikaros (IKZF1) among lymphoid BC pairs. Only 21 recurrently altered genes were affected by somatic SNVs or indels, with resistance-associated ABL1 mutations being commonest.
We next used DNA methylation arrays to assess the BC epigenome, and found 20,651 CpG sites (out of 455,187) to be hyper-methylated, and 3225 to be hypo-methylated in BC compared to CP. Combined methylome and transcriptome analysis demonstrated an inverse relationship between methylation and expression changes at a subset of CpG sites enriched at promoters. Genes with increased methylation/decreased expression or decreased methylation/increased expression included those involved in cell cycle control/heme biosynthesis, and molecular mechanisms of cancer/G-protein coupled receptor signaling/MAPK signaling respectively. Unsupervised methylation-based clustering segregated samples into CP, lymphoid BC and myeloid BC groups, recapitulating expression-based clustering, and further supporting a functional role for DNA methylation in BC transcriptional reprogramming.
We next performed an integrative analysis by combining the genome, methylome, and transcriptome datasets, and included data from 34 additional CML samples. Top ranking candidate genes included epigenetic modifiers, and hematopoetic differentiation- and stem cell-related genes. Functional analysis of candidate genes and epigenetic processes using genetic and epigenetic drug-based approaches are ongoing.
In summary, we conclude that: 1. The genomic and epigenomic landscapes in BC are characterized by a modest number of recurring events in the former, but consistent and striking differences in the latter, 2. The BC methylome is functionally associated with the robust gene expression changes found in BC, and 3. Epigenetic modifier drugs may be of use in reversing the gene expression changes characteristic of BC.
Chuah:Children International: Honoraria; Novartis: Honoraria; Bristol Meyers Squibb: Honoraria. Takahashi:Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Sysmex: Research Funding, Speakers Bureau; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Celgene: Speakers Bureau; Masis: Consultancy; Otsuka: Membership on an entity's Board of Directors or advisory committees; Astellas: Speakers Bureau; BMS: Honoraria, Research Funding, Speakers Bureau.
Targeted next-generation sequencing is becoming increasingly common as a clinical diagnostic and prognostic test for patient- and tumor-specific genetic profiles as well as to optimally select ...targeted therapies. Here, we describe a custom-developed, next-generation sequencing test for detecting single-nucleotide variants (SNVs) and short insertions and deletions (indels) in 93 genes related to gastrointestinal cancer from routine formalin-fixed, paraffin-embedded clinical specimens. We implemented a validation strategy, based on the College of American Pathologists requirements, using reference DNA mixtures from cell lines with known genetic variants, which model a broad range of allele frequencies. Test sensitivity achieved >99% for both SNVs and indels, with allele frequencies >10%, with high specificity (97.4% for SNVs and 93.6% for indels). We further confirmed test accuracies using primary formalin-fixed, paraffin-embedded colorectal cancer specimens characterized by alternative and conventional clinical diagnostic technologies. Robust performance was observed on the formalin-fixed, paraffin-embedded specimens: sensitivity was 97.2% and specificity was 99.2%. We also observed high intrarun and inter-run reproducibility, as well as a low cross-contamination rate. Overall assessment using cell line samples and formalin-fixed, paraffin-embedded samples showed that our custom next-generation sequencing assay has consistent detection sensitivity down to 10% variant frequency.
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