Pancreatic cancer pathology viewed in the light of evolution.

One way to understand ductal adenocarcinoma of the pancreas (pancreatic cancer) is to view it as unimaginably large numbers of evolving living organisms interacting with their environment. This "evolutionary view" creates both expected and surprising perspectives in all stages of neoplastic progression. Advances in the field will require greater attention to this critical evolutionary prospective.

Long-Term Treatment Patterns Among Patients With Psoriasis Treated With Ixekizumab or Adalimumab: A Real-World Study.

BACKGROUND: There is a paucity of long-term real-world evidence comparing the effectiveness of ixekizumab (IXE) and adalimumab (ADA). We compared real-world treatment patterns of IXE-treated and ADA-treated patients with psoriasis over 24 months in the United States. METHODS: A retrospective observational study was conducted using IBM Watson Health MarketScan® databases. Adult patients with psoriasis having ≥1 claim for IXE or ADA from March 1, 2016 – October 31, 2019 were identified. Inverse probability of treatment weighting (IPTW) was used to address cohort imbalances. Cox proportional hazards models were used to estimate the risks of non-persistence, discontinuation, and switching. Logistic regression was used to estimate odds of high adherence. Persistence, adherence, discontinuation, reinitiation, and dosing and switching rates were also analyzed. RESULTS: The final cohorts comprised 475 IXE users and 3159 ADA users over 24 months. IXE users demonstrated higher adherence (36.3% vs 28.8%; P<0.001) and persistence rates (35.2% vs 28.8%; P=0.004), and a lower discontinuation rate (59.1% vs 65.3%; P=0.007) compared to ADA users. IXE users had a higher likelihood of being treatment-adherent compared to ADA users (OR=1.52, 95% CI: 1.24–1.87), a lower risk of non-persistence (HR=0.84, 95% CI: 0.75–0.95), and a lower risk of discontinuation (HR=0.83, 95% CI: 0.74–0.94), respectively. Switching rates were similar in both groups (31.2% vs 30.0%; P=0.608). CONCLUSION: IXE users had better treatment adherence and persistence, and a lower risk of discontinuation compared to ADA users over 24 months. There was no difference in the risk of switching between IXE and ADA. J Drugs Dermatol. 2022;21(4):399-407. doi:10.36849/JDD.6336.

The genetics of ductal adenocarcinoma of the pancreas in the year 2020: dramatic progress, but far to go.

The publication of the "Pan-Cancer Atlas" by the Pan-Cancer Analysis of Whole Genomes Consortium, a partnership formed by The Cancer Genome Atlas (TCGA) and International Cancer Genome Consortium (ICGC), provides a wonderful opportunity to reflect on where we stand in our understanding of the genetics of pancreatic cancer, as well as on the opportunities to translate this understanding to patient care. From germline variants that predispose to the development of pancreatic cancer, to somatic mutations that are therapeutically targetable, genetics is now providing hope, where there once was no hope, for those diagnosed with pancreatic cancer.

Oncogene-induced Nrf2 transcription promotes ROS detoxification and tumorigenesis.

Reactive oxygen species (ROS) are mutagenic and may thereby promote cancer. Normally, ROS levels are tightly controlled by an inducible antioxidant program that responds to cellular stressors and is predominantly regulated by the transcription factor Nrf2 (also known as Nfe2l2) and its repressor protein Keap1 (refs 2-5). In contrast to the acute physiological regulation of Nrf2, in neoplasia there is evidence for increased basal activation of Nrf2. Indeed, somatic mutations that disrupt the Nrf2-Keap1 interaction to stabilize Nrf2 and increase the constitutive transcription of Nrf2 target genes were recently identified, indicating that enhanced ROS detoxification and additional Nrf2 functions may in fact be pro-tumorigenic. Here, we investigated ROS metabolism in primary murine cells following the expression of endogenous oncogenic alleles of Kras, Braf and Myc, and found that ROS are actively suppressed by these oncogenes. K-Ras(G12D), B-Raf(V619E) and Myc(ERT2) each increased the transcription of Nrf2 to stably elevate the basal Nrf2 antioxidant program and thereby lower intracellular ROS and confer a more reduced intracellular environment. Oncogene-directed increased expression of Nrf2 is a new mechanism for the activation of the Nrf2 antioxidant program, and is evident in primary cells and tissues of mice expressing K-Ras(G12D) and B-Raf(V619E), and in human pancreatic cancer. Furthermore, genetic targeting of the Nrf2 pathway impairs K-Ras(G12D)-induced proliferation and tumorigenesis in vivo. Thus, the Nrf2 antioxidant and cellular detoxification program represents a previously unappreciated mediator of oncogenesis.

Genome annotation by shotgun inactivation of a native gene in hemizygous cells: application to BRCA2 with implication of hypomorphic variants.

The greatest interpretive challenge of modern medicine may be to functionally annotate the vast variation of human genomes. Demonstrating a proposed approach, we created a library of BRCA2 exon 27 shotgun-mutant plasmids including solitary and multiplex mutations to generate human knockin clones using homologous recombination. This 55-mutation, 13-clone syngeneic variance library (SyVaL) comprised severely affected clones having early-stop nonsense mutations, functionally hypomorphic clones having multiple missense mutations emphasizing the potential to identify and assess hypomorphic mutations in novel proteomic and epidemiologic studies, and neutral clones having multiple missense mutations. Efficient coverage of nonessential amino acids was provided by mutation multiplexing. Severe mutations were distinguished from hypomorphic or neutral changes by chemosensitivity assays (hypersensitivity to mitomycin C and acetaldehyde), by analysis of RAD51 focus formation, and by mitotic multipolarity. A multiplex unbiased approach of generating all-human SyVaLs in medically important genes, with random mutations in native genes, would provide databases of variants that could be functionally annotated without concerns arising from exogenous cDNA constructs or interspecies interactions, as a basis for subsequent proteomic domain mapping or clinical calibration if desired. Such gene-irrelevant approaches could be scaled up for multiple genes of clinical interest, providing distributable cellular libraries linked to public-shared functional databases.

Hypersensitivities for acetaldehyde and other agents among cancer cells null for clinically relevant Fanconi anemia genes.

Large-magnitude numerical distinctions (>10-fold) among drug responses of genetically contrasting cancers were crucial for guiding the development of some targeted therapies. Similar strategies brought epidemiological clues and prevention goals for genetic diseases. Such numerical guides, however, were incomplete or low magnitude for Fanconi anemia pathway (FANC) gene mutations relevant to cancer in FANC-mutation carriers (heterozygotes). We generated a four-gene FANC-null cancer panel, including the engineering of new PALB2/FANCN-null cancer cells by homologous recombination. A characteristic matching of FANCC-null, FANCG-null, BRCA2/FANCD1-null, and PALB2/FANCN-null phenotypes was confirmed by uniform tumor regression on single-dose cross-linker therapy in mice and by shared chemical hypersensitivities to various inter-strand cross-linking agents and γ-radiation in vitro. Some compounds, however, had contrasting magnitudes of sensitivity; a strikingly high (19- to 22-fold) hypersensitivity was seen among PALB2-null and BRCA2-null cells for the ethanol metabolite, acetaldehyde, associated with widespread chromosomal breakage at a concentration not producing breaks in parental cells. Because FANC-defective cancer cells can share or differ in their chemical sensitivities, patterns of selective hypersensitivity hold implications for the evolutionary understanding of this pathway. Clinical decisions for cancer-relevant prevention and management of FANC-mutation carriers could be modified by expanded studies of high-magnitude sensitivities.

FAM190A deficiency creates a cell division defect.

Like the p16, SMAD4, and RB1 genes, FAM190A (alias CCSER1) lies at a consensus site of homogeneous genomic deletions in human cancer. FAM190A transcripts in 40% of cancers also contain in-frame deletions of evolutionarily conserved exons. Its gene function was unknown. We found an internal deletion of the FAM190A gene in a pancreatic cancer having prominent focal multinuclearity. The experimental knockdown of FAM190A expression by shRNA caused focal cytokinesis defects, multipolar mitosis, and multinuclearity as observed in time-lapse microscopy. FAM190A was localized to the γ-tubulin ring complex of early mitosis and to the midbody in late cytokinesis by immunofluorescence assay and was present in the nuclear fraction of unsynchronized cells by immunoblot. FAM190A interacted with EXOC1 and Ndel1, which function in cytoskeletal organization and the cell division cycle. Levels of FAM190A protein peaked 12 hours after release from thymidine block, corresponding to M-phase. Slower-migrating phosphorylated forms accumulated toward M-phase and disappeared after release from a mitotic block and before cytokinesis. Studies of FAM190A alterations may provide mechanistic insights into mitotic dysregulation and multinuclearity in cancer. We propose that FAM190A is a regulator or structural component required for normal mitosis and that both the rare truncating mutations and common in-frame deletion alteration of FAM190A may contribute to the chromosomal instability of cancer.

Magnetic Resonance Imaging-Based Assessment of Pancreatic Fat Strongly Correlates With Histology-Based Assessment of Pancreas Composition.

OBJECTIVE: The aim of the study is to assess the relationship between magnetic resonance imaging (MRI)-based estimation of pancreatic fat and histology-based measurement of pancreatic composition. MATERIALS AND METHODS: In this retrospective study, MRI was used to noninvasively estimate pancreatic fat content in preoperative images from high-risk individuals and disease controls having normal pancreata. A deep learning algorithm was used to label 11 tissue components at micron resolution in subsequent pancreatectomy histology. A linear model was used to determine correlation between histologic tissue composition and MRI fat estimation. RESULTS: Twenty-seven patients (mean age 64.0 ± 12.0 years [standard deviation], 15 women) were evaluated. The fat content measured by MRI ranged from 0% to 36.9%. Intrapancreatic histologic tissue fat content ranged from 0.8% to 38.3%. MRI pancreatic fat estimation positively correlated with microanatomical composition of fat (r = 0.90, 0.83 to 0.95], P < 0.001); as well as with pancreatic cancer precursor ( r = 0.65, P < 0.001); and collagen ( r = 0.46, P < 0.001) content, and negatively correlated with pancreatic acinar ( r = -0.85, P < 0.001) content. CONCLUSIONS: Pancreatic fat content, measurable by MRI, correlates to acinar content, stromal content (fibrosis), and presence of neoplastic precursors of cancer.

Comparison of Real-World Costs, Healthcare Resource Utilization, and Comorbidity-Related Costs Between Ixekizumab and Secukinumab Among Biologic-Experienced Patients with Psoriasis Over 18 Months in the USA.

BACKGROUND AND OBJECTIVE: Data on real-world healthcare costs for ixekizumab (IXE) and secukinumab (SEC) in biologic-experienced patients with psoriasis are limited. This study compared real-world costs and healthcare resource utilization between IXE and SEC in biologic-experienced patients with psoriasis over an 18-month follow-up period in the USA. METHODS: Adult patients with a diagnosis of psoriasis between 1 March, 2015 and 31 October, 2019 were identified using health insurance claims data from IBM Watson Health MarketScan®. The index date was the date of the first IXE or SEC claim. Biologic-experienced patients with one or more pre-period claims for biologic drugs were identified. Inverse probability of treatment weighting was used to reduce cohort imbalances. All-cause and psoriasis-related direct healthcare costs along with index drug costs were estimated during the follow-up and reported as per patient per month. Discount factors published by the Institute for Clinical and Economic Review were applied to psoriasis-related biologics to adjust pharmacy costs. RESULTS: A total of 411 IXE and 780 SEC users were included. After weighting, all-cause inpatient admissions were similar between IXE (9.5%) and SEC users (10.3%). Weighted, mean ± standard deviation per patient per month all-cause healthcare costs were higher in IXE users ($6670 ± $2910) than in SEC users ($6239 ± $3903; p = 0.049). Psoriasis-related and monthly index drug costs were higher in IXE users ($5609 ± $2009; p < 0.001 and $4688 ± $1994; p < 0.001, respectively) than in SEC users ($5095 ± $2291 and $3853 ± $1977, respectively). After Institute for Clinical and Economic Review adjustment, mean per patient per month all-cause ($4363 ± $2576 vs $4398 ± $3517) and psoriasis-related costs ($3302 ± $1264 vs $3253 ± $1504) were similar between the groups. Institute for Clinical and Economic Review- and adherence-adjusted mean per patient per month index drug costs were similar between IXE and SEC users (p = 0.339). CONCLUSIONS: Institute for Clinical and Economic Review-adjusted all-cause and psoriasis-related costs were comparable between IXE and SEC users among biologic-experienced patients over an 18-month follow-up period.

Unbiased discovery of interactions at a control locus driving expression of the cancer-specific therapeutic and diagnostic target, mesothelin.

Although significant effort is expended on identifying transcripts/proteins that are up-regulated in cancer, there are few reports on systematic elucidation of transcriptional mechanisms underlying such druggable cancer-specific targets. The mesothelin (MSLN) gene offers a promising subject, being expressed in a restricted pattern normally, yet highly overexpressed in almost one-third of human malignancies and a target of cancer immunotherapeutic trials. CanScript, a cis promoter element, appears to control MSLN cancer-specific expression; its related genomic sequences may up-regulate other cancer markers. CanScript is a 20-nt bipartite element consisting of an SP1-like motif and a consensus MCAT sequence. The latter recruits TEAD (TEA domain) family members, which are universally expressed. Exploration of the active CanScript element, especially the proteins binding to the SP1-like motif, thus could reveal cancer-specific features having diagnostic or therapeutic interest. The efficient identification of sequence-specific DNA-binding proteins at a given locus, however, has lagged in biomarker explorations. We used two orthogonal proteomics approaches--unbiased SILAC (stable isotope labeling by amino acids in cell culture)/DNA affinity-capture/mass spectrometry survey (SD-MS) and a large transcription factor protein microarray (TFM)--and functional validation to explore systematically the CanScript interactome. SD-MS produced nine candidates, and TFM, 18. The screens agreed in confirming binding by TEAD proteins and by newly identified NAB1 and NFATc. Among other identified candidates, we found functional roles for ZNF24, NAB1 and RFX1 in MSLN expression by cancer cells. Combined interactome screens yield an efficient, reproducible, sensitive, and unbiased approach to identify sequence-specific DNA-binding proteins and other participants in disease-specific DNA elements.

Structural analysis of the cancer-specific promoter in mesothelin and in other genes overexpressed in cancers.

Mesothelin (MSLN) may be the most "dramatic" of the tumor markers, being strongly overexpressed in nearly one-third of human malignancies. The biochemical cause is unclear. We previously ascribed this cancer-specific overexpression to an element, Canscript, residing around 50 bp 5' of the transcription start site in cancer (Hucl, T., Brody, J. R., Gallmeier, E., Iacobuzio-Donahue, C. A., Farrance, I. K., and Kern, S. E. (2007) Cancer Res. 67, 9055-9065). Herein, we found a Canscript promoter activity elevated over 100-fold in cancer cells. In addition to a highly conserved TEAD1 (TEA domain family member 1)-binding MCAT motif, nucleotide substitution revealed the consensus core sequence (WCYCCACCC) of an SP1-like motif in Canscript. The unknown transcription factor binding to the SP1-like motif may hold the key for the cancer specificity of Canscript. SP1, GLI1, and RUNX1, -2, and -3 appeared unlikely to be the direct transcription factors acting at the SP1-like motif, but KLF6 had some features of such a candidate. YAP1, a TEAD1-binding protein, appeared necessary, but not sufficient, for Canscript activity; knockdown of YAP1 by small interfering RNAs greatly reduced MSLN levels in MSLN-overexpressing cells, but overexpressing YAP1 in MSLN-negative cells did not induce MSLN expression. Cansript-like sequences were found in other genes up-regulated in pancreatic cancer; reporters driven by the sequences from FXYD3, MUC1, and TIMP1 had activities more than 2 times that of the control. This suggested that the cause of MSLN overexpression might also contribute mechanistically to the overexpression of other tumor markers.

The complexity of pancreatic ductal cancers and multidimensional strategies for therapeutic targeting.

The directions of differentiation and the molecular features of ductal pancreatic cancer have by now been explored in reasonable detail. Already, diagnoses and therapeutic strategies benefit from observations distinguishing the major variant types of pancreatic cancer and the differing stages of disease at presentation. Additionally, individual patients differ within each variant type. In certain high-risk groups, this permits focused screening efforts. The tumorigenic influences that characterize individual patients are increasingly considered appropriate in defining clinical treatment plans. As a result, multiple variables affect success when individualizing screening or therapy. These competing variables often limit the potential for success: some variables dominate and should receive greater consideration than others. Simplistic expectations, often falsely optimistic, for individualized care may fail to 'pan out' in the real world. The development of individualized care will be efficient only when the full complexity of the disease is embraced.

Healthcare resource utilization and costs among patients with psoriasis treated with ixekizumab or adalimumab over 2 years of follow-up in real-world settings.

AIMS: To compare long-term healthcare resource utilization (HCRU) and costs among patients who initiated ixekizumab (IXE) or adalimumab (ADA) for treatment of psoriasis in the United States. METHODS: Adult patients with psoriasis who had ≥1 claim for IXE or ADA were identified from IBM MarketScan claims databases prior to the COVID-19 pandemic (1 March 2016-31 October 2019). The index date was the date of first claim for the index drug of interest. Inverse probability of treatment weighting was employed to balance treatment cohorts. All-cause and psoriasis-related HCRU and costs were examined for 24 months of follow-up. Costs were reported as per patient per month. Costs of psoriasis-related biologics were adjusted using published Institute for Clinical and Economic Review (ICER) discount factors. Index drug costs were adjusted for adherence and ICER discount rates. RESULTS: The analyses included 407 IXE and 2,702 ADA users. IXE users had significantly higher inpatient admission rate (all-cause HCRU: 14.9% vs. 11.0%; p =0.012) and greater mean length of stay per admission (days, 6.6 vs. 4.1; p =0.004) than ADA users. ICER-adjusted costs were significantly higher in IXE than ADA users (all-cause costs: $4,132 vs. $3,610; p <0.001; psoriasis-related costs $3,077 vs. $2,700; p <0.001). After adjusting for ICER and adherence, IXE and ADA drug costs were comparable ($3,636 vs. $3,677; p =0.714). LIMITATIONS: Study relied on administrative claims data, subjected to data coding limitations and data entry errors. Rebates, patient assistance programs, and commission to wholesalers are not always captured in claims. Adjustment made by ICER discount factors may lead to double-discounting if the discounts have been applied in claim payments. CONCLUSIONS: All-cause HCRU was higher in IXE than ADA users. Healthcare costs were also higher in IXE than ADA users after ICER adjustment, over 24 months. Cost differences were largely driven by higher treatment adherence associated with IXE. Index drug costs were comparable after ICER and adherence adjustments.

Treatment patterns and health care costs among patients with psoriatic arthritis treated with biologic or targeted synthetic disease-modifying antirheumatic drugs.

BACKGROUND: Biologic and targeted synthetic disease-modifying antirheumatic drug (tsDMARD) therapies are used in management of psoriatic arthritis (PsA). Although previous studies have demonstrated that rates of adherence, persistence, discontinuation, and switching, as well as health care costs, are variable among treatments, limited published data exist on more recently approved therapies. OBJECTIVE: To describe adherence, persistence, discontinuation, reinitiation, switching, dosing patterns, and health care costs among PsA patients treated with biologics and tsDMARDs. METHODS: This was a real-world, retrospective administrative claims study. Adult PsA patients with at least 1 claim for an approved PsA biologic (adalimumab, certolizumab, etanercept, golimumab, infliximab, secukinumab, or ustekinumab) or tsDMARD (apremilast or tofacitinib) between January 1, 2015, and June 30, 2019, were selected from the IBM MarketScan administrative claims databases. The first claim for one of the study treatments determined the index date and drug cohort. Patients were required to be continuously enrolled in their health plans for 12 months before and after the index date and to have at least 1 claim with a diagnosis of PsA in the 12 months before or on the index date. Adherence (measured by proportion of days covered [PDC] and medication possession ratio [MPR]), persistence (< 60-day gap in treatment), discontinuation (> 90-day gap), reinitiation of index drug, switching, and dosing patterns for each index drug were assessed during the 12-month follow-up period. Health care costs were reported per patient per month (PPPM) during the 12-month follow-up and assessed after adjusting PsA treatment costs by the Institute for Clinical and Economic Review discount factors to account for discounts and rebates not usually reflected in claims data and by adherence. RESULTS: Overall, 6,674 patients met the selection criteria. The top 3 index drugs were adalimumab (37%), apremilast (26%), and etanercept (18%). Over 12 months of follow-up, 31%-59% of patients remained persistent on the index drug, whereas 35%-56% discontinued, 13%-29% switched to a different biologic or tsDMARD, and 3%-15% reinitiated the index therapy, depending on the index drug. The mean PDC ranged from 0.51 to 0.69 during the 12-month follow-up and 0.80 to 0.93 during the follow-up period before discontinuation. Dose values were largely consistent with prescribing information, with the exception of secukinumab. Index drug costs PPPM ranged from $2,361 (apremilast) to $6,528 for ustekinumab after adjustment for discounts and adherence. CONCLUSIONS: Results from this real-world analysis suggest that there is substantial variability in persistence, discontinuation, adherence, reinitiating, and switching patterns among the different biologic and tsDMARD treatment options for PsA patients. In addition, this study provides real-world cost data for biologics and tsDMARDs among patients with PsA. DISCLOSURES: This study was funded by Eli Lilly Inc., which participated in analysis and interpretation of data, drafting, reviewing, and approving the publication. All authors contributed to the development of the publication and maintained control over the final content. Murage, Malatestinic, Zhu, Atiya, Kern, Stenger, and Sprabery are employees and stockholders of Eli Lilly Inc. Princic and Park are employed by IBM Watson Health, which received funding from Eli Lilly Inc. to conduct this study. Ogdie has received consulting fees from Amgen, AbbVie, Bristol-Myers Squibb, Celgene, Corrona, Janssen, Lilly, Novartis, and Pfizer and has also received grant support from Pfizer, Novartis, and Amgen. Portions of these data have been presented in poster form at the virtual International Society for Pharmacoeconomics and Outcomes Research (ISPOR) 2020 and Congress of Clinical Rheumatology (CCR) West 2020 conferences.

Real-World Treatment Patterns and Healthcare Costs in Patients with Psoriatic Arthritis Treated with Ixekizumab: A Retrospective Study.

OBJECTIVE: To describe adherence, persistence, discontinuation, restarting, switching, dosing, and health care costs among patients with psoriatic arthritis (PsA) treated with ixekizumab (IXE). METHODS: MarketScan administrative claims databases were used to select adults (≥18 years) initiating IXE between January 1, 2016, and June 30, 2019, for this retrospective study (earliest IXE claim = index). Eligible patients had one or more PsA diagnoses during the 12 months preceding the index and had 12 months of follow-up time after the index. Adherence (measured by proportion of days covered [PDC]) persistence (<60-day gap), discontinuation (≥90-day gap), switching, and dosing patterns were reported. Health care costs were reported per patient per month (PPPM) during follow-up and were assessed after adjusting PsA treatment costs for discount rates reported by the Institute for Clinical and Economic Review (ICER). RESULTS: A total of 496 patients met the selection criteria (mean age, 51.1 years; 50.4% female). Over the 12-month follow-up, 52.8% remained persistent, 38.7% discontinued, 13.5% had no other treatment, 4.6% restarted, and 20.6% switched to a new biologic/traditional synthetic disease-modifying antirheumatic drug. 70.6%of patients were identified as highly adherent (i.e. PDC > 0.80)to IXE prior to discontinuation. Dose values were consistent with prescribing information for patients with and without comorbid psoriasis. Although IXE costs ($5233 [SD = $2497]) accounted for 85.6% of PsA-related health care costs, only 3.5% of IXE costs were patient out-of-pocket expenses. Adjusting for the ICER discounts decreased all-cause and PsA-related costs by $2509 PPPM. CONCLUSION: Results from this real-world analysis suggest that treatment patterns and costs among patients with PsA initiating IXE are consistent with prior literature for other biologics.

Absence of E-cadherin expression distinguishes noncohesive from cohesive pancreatic cancer.

PURPOSE: The role of E-cadherin in carcinogenesis is of great interest, but few studies have examined its relevance to pancreatic carcinoma. EXPERIMENTAL DESIGN: We evaluated E-cadherin protein expression by immunohistochemistry in pancreatobiliary cancers having a noncohesive histologic phenotype (21 undifferentiated adenocarcinomas and 7 signet ring carcinomas), comparing the results with pancreatic cancers having a cohesive phenotype (25 moderately differentiated and 14 poorly differentiated adenocarcinomas). RESULTS: Twenty of 21 undifferentiated cancers had complete absence of E-cadherin expression, as did two signet ring carcinomas. In contrast, cohesive cancers (n = 39) had E-cadherin labeling at the plasma membrane (P < 0.001). Subsets of cancers were also evaluated for beta-catenin expression. All of the cohesive lesions (n = 28) showed a membranous beta-catenin expression pattern, whereas noncohesive foci (n = 7) were characterized by either cytoplasmic labeling or complete absence of beta-catenin protein expression, suggestive of a deficient zonula adherens in noncohesive cancers. E-cadherin promoter hypermethylation was observed in an undifferentiated pancreatic cancer cell line, MiaPaCa-2, whereas two pancreatic cancer cell lines derived from differentiated lesions lacked any evidence of E-cadherin promoter methylation. No pattern of E-cadherin promoter methylation could be determined in three primary cancers having mixed histologic patterns (contained both cohesive and noncohesive foci). No somatic mutations in E-cadherin were identified in noncohesive pancreatic cancers having inactivated E-cadherin. CONCLUSIONS: Noncohesive pancreatic cancers were characterized by the loss of E-cadherin protein expression. Promoter hypermethylation is a possible mechanism of E-cadherin gene silencing in a subset of these cancers.

SOS1 mutations are rare in human malignancies: implications for Noonan Syndrome patients.

Germ line gain-of-function mutations in several members of the RAS/ERK pathway, including PTPN11, KRAS, and RAF1, cause the autosomal dominant genetic disorder Noonan Syndrome (NS). NS patients are at increased risk of leukemia/myeloproliferative disease and possibly some solid tumors, such as neuroblastoma. Recently, SOS1 gain of function mutations have also been shown to cause NS. Somatic PTPN11, KRAS, and RAF1 mutations occur (although at different frequencies) in a variety of sporadic neoplasms, but whether SOS1 mutations are associated with human cancer has not been evaluated. We sequenced DNA from a total of 810 primary malignancies, including pancreatic, lung, breast, and colon carcinomas, and acute myelogenous leukemia, as well as several neuroblastoma cell lines. From this large, diverse series, missense SOS1 mutations were identified in a single pancreatic tumor, one lung adenocarcinoma, and a T-cell acute lymphoblastic leukemia cell line. Our findings suggest that SOS1 is not a significant human oncogene in most cancers. Furthermore, NS patients with SOS1 mutations may not be at increased risk of developing cancer.

The fuzzy math of solid tumor stem cells: a perspective.

Apparently effective therapeutic agents very often fail to cure cancer patients. It is therefore attractive to wonder whether a specific resistant cell subset should be recognized and separately targeted. In solid tumors, such as carcinomas, a minor population of "cancer stem cells" has been proposed and sought experimentally in human tumors and isolated cell populations. It is often overlooked that the rationale and supportive data are essentially numerical and can be evaluated as such. A reevaluation of the published studies and related claims within awarded U.S. patents suggests that the mathematical support for the concept of therapeutically useful stem cells is weak and may even invalidate the foundations of these publications and patent claims. Mathematical arguments should be used more consistently, because they can serve as a guide for interpreting studies into cancer stem cells of solid tumors.

High cancer-specific expression of mesothelin (MSLN) is attributable to an upstream enhancer containing a transcription enhancer factor dependent MCAT motif.

Identification of genes with cancer-specific overexpression offers the potential to efficiently discover cancer-specific activities in an unbiased manner. We apply this paradigm to study mesothelin (MSLN) overexpression, a nearly ubiquitous, diagnostically and therapeutically useful characteristic of pancreatic cancer. We identified an 18-bp upstream enhancer, termed CanScript, strongly activating transcription from an otherwise weak tissue-nonspecific promoter and operating selectively in cells having aberrantly elevated cancer-specific MSLN transcription. Introducing mutations into CanScript showed two functionally distinct sites: an Sp1-like site and an MCAT element. Gel retardation and chromatin immunoprecipitation assays showed the MCAT element to be bound by transcription enhancer factor (TEF)-1 (TEAD1) in vitro and in vivo. The presence of TEF-1 was required for MSLN protein overexpression as determined by TEF-1 knockdown experiments. The cancer specificity seemed to be provided by a putative limiting cofactor of TEF-1 that could be outcompeted by exogenous TEF-1 only in a MSLN-overexpressing cell line. A CanScript concatemer offered enhanced activity. These results identify a TEF family member as a major regulator of MSLN overexpression, a fundamental characteristic of pancreatic and other cancers, perhaps due to an upstream and highly frequent aberrant cellular activity. The CanScript sequence represents a modular element for cancer-specific targeting, potentially suitable for nearly a third of human malignancies.