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Hypermutator Pseudomonas aeruginosa Exploits Multiple Genetic Pathways To Develop Multidrug Resistance during Long-Term Infections in the Airways of Cystic Fibrosis Patients [Mechanisms of Resistance]

Pseudomonas aeruginosa exploits intrinsic and acquired resistance mechanisms to resist almost every antibiotic used in chemotherapy. Antimicrobial resistance in P. aeruginosa isolates recovered from cystic fibrosis (CF) patients is further enhanced by the occurrence of hypermutator strains, a hallmark of chronic infections in CF patients. However, the within-patient genetic diversity of P. aeruginosa populations related to antibiotic resistance remains unexplored. Here, we show the evolution of the mutational resistome profile of a P. aeruginosa hypermutator lineage by performing longitudinal and transversal analyses of isolates collected from a CF patient throughout 20 years of chronic infection. Our results show the accumulation of thousands of mutations, with an overall evolutionary history characterized by purifying selection. However, mutations in antibiotic resistance genes appear to have been positively selected, driven by antibiotic treatment. Antibiotic resistance increased as infection progressed toward the establishment of a population constituted by genotypically diversified coexisting sublineages, all of which converged to multidrug resistance. These sublineages emerged by parallel evolution through distinct evolutionary pathways, which affected genes of the same functional categories. Interestingly, ampC and ftsI, encoding the β-lactamase and penicillin-binding protein 3, respectively, were found to be among the most frequently mutated genes. In fact, both genes were targeted by multiple independent mutational events, which led to a wide diversity of coexisting alleles underlying β-lactam resistance. Our findings indicate that hypermutators, apart from boosting antibiotic resistance evolution by simultaneously targeting several genes, favor the emergence of adaptive innovative alleles by clustering beneficial/compensatory mutations in the same gene, hence expanding P. aeruginosa strategies for persistence.




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In Vitro Activity of Beauvericin against All Developmental Stages of Sarcoptes scabiei [Susceptibility]

Scabies is a frequent cutaneous infection caused by the mite Sarcoptes scabiei in a large number of mammals, including humans. As the resistance of S. scabiei against several chemical acaricides has been previously documented, the establishment of alternative and effective control molecules is required. In this study, the potential acaricidal activity of beauvericin was assessed against different life stages of S. scabiei var. suis and in comparison with dimpylate and ivermectin, two commercially available molecules used for the treatment of S. scabiei infection in animals and/or humans. The toxicity of beauvericin against cultured human fibroblast skin cells was evaluated using an MTT proliferation assay. In our in vitro model, developmental stages of S. scabiei were placed in petri dishes filled with Columbia agar supplemented with pig serum and different concentrations of the drugs. Cell sensitivity assays demonstrated low toxicity of beauvericin against primary human fibroblast skin cells. At 0.5 and 5 mM, beauvericin showed higher activity against adults and eggs of S. scabiei compared to dimpylate and ivermectin. These results revealed that the use of beauvericin is promising and might be considered for the treatment of S. scabiei infection.




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Impact of Daptomycin Dose Exposure Alone or in Combination with {beta}-Lactams or Rifampin against Vancomycin-Resistant Enterococci in an In Vitro Biofilm Model [Susceptibility]

Enterococcus faecium strains are commonly resistant to vancomycin and β-lactams. In addition, E. faecium often causes biofilm-associated infections and these infections are difficult to treat. In this context, we investigated the activity of dosing regimens using daptomycin (DAP) (8, 10, 12, and 14 mg/kg of body weight/day) alone and in combination with ceftaroline (CPT), ampicillin (AMP), ertapenem (ERT), and rifampin (RIF) against 2 clinical strains of biofilm-producing vancomycin-resistant Enterococcus faecium (VREfm), namely, strains S447 and HOU503, in an in vitro biofilm model. HOU503 harbors common LiaS and LiaR substitutions, whereas S447 lacks mutations associated with the LiaFSR pathway. MIC results demonstrated that both strains were susceptible to DAP and resistant to CPT, AMP, ERT, and RIF. The 168-h pharmacokinetic/pharmacodynamic (PK/PD) CDC biofilm reactor models (simulating human antibiotic exposures) were used with titanium and polyurethane coupons to evaluate the efficacy of antibiotic combinations. DAP 12 and 14 achieved bactericidal activity against S447 but lacked such effect against HOU503. Addition of ERT and RIF enhanced DAP activity, allowing DAP 8 and 10 plus ERT or RIF to produce bactericidal activity against both strains at 168 h. While DAP 8 and 10 plus CPT improved killing, they did not reach bactericidal reduction against S447. Combination of AMP, CPT, ERT, or RIF resulted in enhanced and bactericidal activity for DAP against HOU503 at 168 h. Our data provide further support for the use of combinations of DAP with AMP, ERT, CPT, and RIF in infections caused by biofilm producing VREfm. Further research involving DAP combinations against biofilm-producing enterococci is warranted.




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Antimicrobial Activity of the Quinoline Derivative HT61 against Staphylococcus aureus Biofilms [Susceptibility]

Staphylococcus aureus biofilms are a significant problem in health care settings, partly due to the presence of a nondividing, antibiotic-tolerant subpopulation. Here we evaluated treatment of S. aureus UAMS-1 biofilms with HT61, a quinoline derivative shown to be effective against nondividing Staphylococcus spp. HT61 was effective at reducing biofilm viability and was associated with increased expression of cell wall stress and division proteins, confirming its potential as a treatment for S. aureus biofilm infections.




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Comparison of Commensal and Clinical Isolates for Diversity of Plasmids in Escherichia coli and Klebsiella pneumoniae [Epidemiology and Surveillance]

In this study, the plasmid content of clinical and commensal strains was analyzed and compared. The replicon profile was similar in both populations, except for L, M, A/C, and N (detected only in clinical strains) and HI1 (only in commensal strains). Although I1 and F were the most frequent replicons, only IncI1, sequence type 12 (ST12) was associated with blaCMY-2 in both populations. In contrast, the widespread resistant IncF plasmids were not linked to a single epidemic plasmid.




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Novel Insights into Plasmodium vivax Therapeutic Failure: CYP2D6 Activity and Time of Exposure to Malaria Modulate the Risk of Recurrence [Epidemiology and Surveillance]

Plasmodium vivax relapse is one of the major causes of sustained global malaria transmission. Primaquine (PQ) is the only commercial drug available to prevent relapses, and its efficacy is dependent on metabolic activation by cytochrome P450 2D6 (CYP2D6). Impaired CYP2D6 function, caused by allelic polymorphisms, leads to the therapeutic failure of PQ as a radical cure for P. vivax malaria. Here, we hypothesized that the host immune response to malaria parasites modulates susceptibility to P. vivax recurrences in association with CYP2D6 activity. We performed a 10-year retrospective study by genotyping CYP2D6 polymorphisms in 261 malaria-exposed individuals from the Brazilian Amazon. The immune responses against a panel of P. vivax blood-stage antigens were evaluated by serological assays. We confirmed our previous findings, which indicated an association between impaired CYP2D6 activity and a higher risk of multiple episodes of P. vivax recurrence (risk ratio, 1.75; 95% confidence interval [CI], 1.2 to 2.6; P = 0.0035). An important finding was a reduction of 3% in the risk of recurrence (risk ratio, 0.97; 95% CI, 0.96 to 0.98; P < 0.0001) per year of malaria exposure, which was observed for individuals with both reduced and normal CYP2D6 activity. Accordingly, subjects with long-term malaria exposure and persistent antibody responses to various antigens showed fewer episodes of malaria recurrence. Our findings have direct implications for malaria control, since it was shown that nonimmune individuals who do not respond adequately to treatment due to reduced CYP2D6 activity may present a significant challenge for sustainable progress toward P. vivax malaria elimination.




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Early Bactericidal Activity Trial of Nitazoxanide for Pulmonary Tuberculosis [Clinical Therapeutics]

This study was conducted in treatment-naive adults with drug-susceptible pulmonary tuberculosis in Port-au-Prince, Haiti, to assess the safety, bactericidal activity, and pharmacokinetics of nitazoxanide (NTZ). This was a prospective phase II clinical trial in 30 adults with pulmonary tuberculosis. Twenty participants received 1 g of NTZ orally twice daily for 14 days. A control group of 10 participants received standard therapy over 14 days. The primary outcome was the change in time to culture positivity (TTP) in an automated liquid culture system. The most common adverse events seen in the NTZ group were gastrointestinal complaints and headache. The mean change in TTP in sputum over 14 days in the NTZ group was 3.2 h ± 22.6 h and was not statistically significant (P = 0.56). The mean change in TTP in the standard therapy group was significantly increased, at 134 h ± 45.2 h (P < 0.0001). The mean NTZ MIC for Mycobacterium tuberculosis isolates was 12.3 μg/ml; the mean NTZ maximum concentration (Cmax) in plasma was 10.2 μg/ml. Negligible NTZ levels were measured in sputum. At the doses used, NTZ did not show bactericidal activity against M. tuberculosis. Plasma concentrations of NTZ were below the MIC, and its negligible accumulation in pulmonary sites may explain the lack of bactericidal activity. (This study has been registered at ClinicalTrials.gov under identifier NCT02684240.)




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Activity of Cefiderocol and Comparators against Isolates from Cancer Patients [Susceptibility]

Cefiderocol inhibited 97.5% of 478 Gram-negative isolates from cancer patients at ≤4 mg/liter. It had potent activity against extended-spectrum β-lactamase-positive Enterobacteriaceae, carbapenem-resistant Enterobacteriaceae (CRE), and nonfermenting Gram-negative bacilli, including Pseudomonas aeruginosa, Stenotrophomonas maltophilia, and Acinetobacter species isolates. Amikacin, ceftazidime-avibactam, and meropenem had appreciable activity against non-CRE Enterobacteriaceae. No comparators were active against multidrug-resistant P. aeruginosa isolates. Only trimethoprim-sulfamethoxazole had appreciable activity against S. maltophilia isolates. Overall, cefiderocol was associated with the lowest level of resistance.




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Antiviral Activity of a Llama-Derived Single-Domain Antibody against Enterovirus A71 [Antiviral Agents]

In the past few decades, enterovirus A71 (EVA71) has caused devastating outbreaks in the Asia-Pacific region, resulting in serious sequelae in infected young children. No preventive or therapeutic interventions are currently available for curing EVA71 infection, highlighting a great unmet medical need for this disease. Here, we showed that one novel single-domain antibody (sdAb), F1, isolated from an immunized llama, could alleviate EVA71 infection both in vitro and in vivo. We also confirmed that the sdAb clone F1 recognizes EVA71 through a novel conformational epitope comprising the highly conserved region of VP3 capsid protein by using competitive-binding and overlapping-peptide enzyme-linked immunosorbent assays (ELISAs). Because of the virion’s icosahedral structure, we reasoned that adjacent epitopes must be clustered within molecular ranges that may be simultaneously bound by an engineered antibody with multiple valency. Therefore, two single-domain binding modules (F1) were fused to generate an sdAb-in-tandem design so that the capture of viral antigens could be further increased by valency effects. We showed that the tetravalent construct F1xF1-hFc, containing two sdAb-in-tandem on a fragment crystallizable (Fc) scaffold, exhibits more potent neutralization activity against EVA71 than does the bivalent sdAb F1-hFc by at least 5.8-fold. We also demonstrated that, using a human scavenger receptor class B member 2 (hSCARB2) transgenic mouse model, a half dose of the F1xF1-hFc provided better protection against EVA71 infection than did the F1-hFc. Thus, our study furnishes important insights into multivalent sdAb engineering against viral infection and provides a novel strategic deployment approach for preparedness of emerging infectious diseases such as EVA71.




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Whole-Cell Phenotypic Screening of Medicines for Malaria Venture Pathogen Box Identifies Specific Inhibitors of Plasmodium falciparum Late-Stage Development and Egress [Experimental Therapeutics]

We report a systematic, cellular phenotype-based antimalarial screening of the Medicines for Malaria Venture Pathogen Box collection, which facilitated the identification of specific blockers of late-stage intraerythrocytic development of Plasmodium falciparum. First, from standard growth inhibition assays, we identified 173 molecules with antimalarial activity (50% effective concentration [EC50] ≤ 10 μM), which included 62 additional molecules over previously known antimalarial candidates from the Pathogen Box. We identified 90 molecules with EC50 of ≤1 μM, which had significant effect on the ring-trophozoite transition, while 9 molecules inhibited the trophozoite-schizont transition and 21 molecules inhibited the schizont-ring transition (with ≥50% parasites failing to proceed to the next stage) at 1 μM. We therefore rescreened all 173 molecules and validated hits in microscopy to prioritize 12 hits as selective blockers of the schizont-ring transition. Seven of these molecules inhibited the calcium ionophore-induced egress of Toxoplasma gondii, a related apicomplexan parasite, suggesting that the inhibitors may be acting via a conserved mechanism which could be further exploited for target identification studies. We demonstrate that two molecules, MMV020670 and MMV026356, identified as schizont inhibitors in our screens, induce the fragmentation of DNA in merozoites, thereby impairing their ability to egress and invade. Further mechanistic studies would facilitate the therapeutic exploitation of these molecules as broadly active inhibitors targeting late-stage development and egress of apicomplexan parasites relevant to human health.




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Adduct Formation of Delamanid with NAD in Mycobacteria [Mechanisms of Action]

Delamanid (DLM), a nitro-dihydroimidazooxazole derivative currently approved for pulmonary multidrug-resistant tuberculosis (TB) therapy, is a prodrug activated by mycobacterial 7,8-didemethyl-8-hydroxy 5-deazaflavin electron transfer coenzyme (F420)-dependent nitroreductase (Ddn). Despite inhibiting the biosynthesis of a subclass of mycolic acids, the active DLM metabolite remained unknown. Comparative liquid chromatography-mass spectrometry (LC-MS) analysis of DLM metabolites revealed covalent binding of reduced DLM with a nicotinamide ring of NAD derivatives (oxidized form) in DLM-treated Mycobacterium tuberculosis var. Bacille de Calmette et Guérin. Isoniazid-resistant mutations in the type II NADH dehydrogenase gene (ndh) showed a higher intracellular NADH/NAD ratio and cross-resistance to DLM, which were restored by complementation of the mutants with wild-type ndh. Our data demonstrated for the first time the adduct formation of reduced DLM with NAD in mycobacterial cells and its importance in the action of DLM.




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Distinct Mechanisms of Dissemination of NDM-1 Metallo-{beta}-Lactamase in Acinetobacter Species in Argentina [Epidemiology and Surveillance]

A 4-year surveillance of carbapenem-resistant Acinetobacter spp. isolates in Argentina identified 40 strains carrying blaNDM-1. Genome sequencing revealed that most were Acinetobacter baumannii, whereas seven represented other Acinetobacter spp. The A. baumannii genomes were closely related, suggesting recent spread. blaNDM-1 was located in the chromosome of A. baumannii strains and on a plasmid in non-A. baumannii strains. A resistance gene island carrying blaPER-7 and other resistance determinants was found on a plasmid in some A. baumannii strains.




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Enhanced Efflux Pump Expression in Candida Mutants Results in Decreased Manogepix Susceptibility [Mechanisms of Resistance]

Manogepix is a broad-spectrum antifungal agent that inhibits glycosylphosphatidylinositol (GPI) anchor biosynthesis. Using whole-genome sequencing, we characterized two efflux-mediated mechanisms in the fungal pathogens Candida albicans and Candida parapsilosis that resulted in decreased manogepix susceptibility. In C. albicans, a gain-of-function mutation in the transcription factor gene ZCF29 activated expression of ATP-binding cassette transporter genes CDR11 and SNQ2. In C. parapsilosis, a mitochondrial deletion activated expression of the major facilitator superfamily transporter gene MDR1.




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Characterization of blaCTX-M-27/F1:A2:B20 Plasmids Harbored by Escherichia coli Sequence Type 131 Sublineage C1/H30R Isolates Spreading among Elderly Japanese in Nonacute-Care Settings [Mechanisms of Resistance]

We characterized 29 blaCTX-M-27-harboring plasmids of Escherichia coli sequence type 131 (ST131) sublineage C1/H30R isolates from healthy individuals and long-term-care facility (LTCF) residents. Most (27/29) plasmids were of the FIA, FIB, and FII multireplicon type with the same plasmid multilocus sequence typing (pMLST). Several plasmids (7/23) from LTCF residents harbored only blaCTX-M-27 as the resistance gene; however, their fundamental structures were very similar to those of previously isolated blaCTX-M-27/F1:A2:B20 plasmids, suggesting their prevalence as a newly arising public health concern.




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Molecular and Clinical Characterization of Multidrug-Resistant and Hypervirulent Klebsiella pneumoniae Strains from Liver Abscess in Taiwan [Epidemiology and Surveillance]

Hypervirulent Klebsiella pneumoniae strains are the major cause of liver abscesses throughout East Asia, and these strains are usually antibiotic susceptible. Recently, multidrug-resistant and hypervirulent (MDR-HV) K. pneumoniae strains have emerged due to hypervirulent strains acquiring antimicrobial resistance determinants or the transfer of a virulence plasmid into a classic MDR strain. In this study, we characterized the clinical and microbiological properties of K. pneumoniae liver abscess (KPLA) caused by MDR-HV strains in Taiwan. Patients with community onset KPLA were retrospectively identified at Taipei Veterans General Hospital during January 2013 to May 2018. Antimicrobial resistance mechanisms, capsular types, and sequence types were determined. MDR-HV strains and their parental antimicrobial-susceptible strains further underwent whole-genome sequencing (WGS) and in vivo mice lethality tests. Thirteen MDR-HV strains were identified from a total of 218 KPLA episodes. MDR-HV strains resulted in similar outcomes to antimicrobial-susceptible strains. All MDR-HV strains were traditional hypervirulent clones carrying virulence capsular types. The major resistance mechanisms were the overexpression of efflux pumps and/or the acquisition of ESBL or AmpC β-lactamase genes. WGS revealed that two hypervirulent strains had evolved to an MDR phenotype due to mutation in the ramR gene and the acquisition of an SHV-12-bearing plasmid, respectively. Both these MDR-HV strains retained high virulence compared to their parental strains. The spread of MDR-HV K. pneumoniae strains in the community raises significant public concerns, and measures should be taken to prevent the further acquisition of carbapenemase and other resistance genes among these strains in order to avoid the occurrence of untreatable KPLA.




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The Novel Macrolide Resistance Genes mef(D), msr(F), and msr(H) Are Present on Resistance Islands in Macrococcus canis, Macrococcus caseolyticus, and Staphylococcus aureus [Mechanisms of Resistance]

Chromosomal resistance islands containing the methicillin resistance gene mecD (McRImecD) have been reported in Macrococcus caseolyticus. Here, we identified novel macrolide resistance genes in Macrococcus canis on similar elements, called McRImsr. These elements were also integrated into the 3' end of the 30S ribosomal protein S9 gene (rpsI), delimited by characteristic attachment (att) sites, and carried a related site-specific integrase gene (int) at the 5' end. They carried novel macrolide resistance genes belonging to the msr family of ABC subfamily F (ABC-F)-type ribosomal protection protein [msr(F) and msr(H)] and the macrolide efflux mef family [mef(D)]. Highly related mef(D)-msr(F) fragments were found on diverse McRImsr elements in M. canis, M. caseolyticus, and Staphylococcus aureus. Another McRImsr-like element identified in an M. canis strain lacked the classical att site at the 3' end and carried the msr(H) gene but no neighboring mef gene. The expression of the novel resistance genes in S. aureus resulted in a low-to-moderate increase in the MIC of erythromycin but not streptogramin B. In the mef(D)-msr(F) operon, the msr(F) gene was shown to be the crucial determinant for macrolide resistance. The detection of circular forms of McRImsr and the mef(D)-msr(F) fragment suggested mobility of both the island and the resistance gene subunit. The discovery of McRImsr in different Macrococcus species and S. aureus indicates that these islands have a potential for dissemination of antibiotic resistance within the Staphylococcaceae family.




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Levonadifloxacin, a Novel Benzoquinolizine Fluoroquinolone, Modulates Lipopolysaccharide-Induced Inflammatory Responses in Human Whole-Blood Assay and Murine Acute Lung Injury Model [Pharmacology]

Fluoroquinolones are reported to possess immunomodulatory activity; hence, a novel benzoquinolizine fluoroquinolone, levonadifloxacin, was evaluated in lipopolysaccharide-stimulated human whole-blood (HWB) and mouse acute lung injury (ALI) models. Levonadifloxacin significantly mitigated the inflammatory responses in an HWB assay through inhibition of proinflammatory cytokines and in the ALI model by lowering lung total white blood cell count, myeloperoxidase, and cytokine levels. The immunomodulatory effect of levonadifloxacin, along with promising antibacterial activity, is expected to provide clinical benefits in the treatment of infections.




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Encephalitozoon cuniculi Genotype III Evinces a Resistance to Albendazole Treatment in both Immunodeficient and Immunocompetent Mice [Experimental Therapeutics]

Of four genotypes of Encephalitozoon cuniculi, E. cuniculi genotype II is considered to represent a parasite that occurs in many host species in a latent asymptomatic form, whereas E. cuniculi genotype III seems to be more aggressive, and infections caused by this strain can lead to the death of even immunocompetent hosts. Although albendazole has been considered suitable for treatment of Encephalitozoon species, its failure in control of E. cuniculi genotype III infection has been reported. This study determined the effect of a 100x recommended daily dose of albendazole on an Encephalitozoon cuniculi genotype III course of infection in immunocompetent and immunodeficient mice and compared the results with those from experiments performed with a lower dose of albendazole and E. cuniculi genotype II. The administration of the regular dose of abendazole during the acute phase of infection reduced the number of affected organs in all strains of mice and absolute counts of spores in screened organs. However, the effect on genotype III was minor. Surprisingly, no substantial effect was recorded after the use of a 100x dose of albendazole, with larger reductions seen only in the number of affected organs and absolute counts of spores in all strains of mice, implying variations in albendazole resistance between these Encephalitozoon cuniculi genotypes. These results imply that differences in the course of infection and the response to treatment depend not only on the immunological status of the host but also on the genotype causing the infection. Understanding how microsporidia survive in hosts despite targeted antimicrosporidial treatment could significantly contribute to research related to human health.




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Correction: Senescence Sensitivity of Breast Cancer Cells Is Defined by Positive Feedback Loop between CIP2A and E2F1 [Correction]




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Tuning the Antigen Density Requirement for CAR T-cell Activity [Research Articles]

Insufficient reactivity against cells with low antigen density has emerged as an important cause of chimeric antigen receptor (CAR) T-cell resistance. Little is known about factors that modulate the threshold for antigen recognition. We demonstrate that CD19 CAR activity is dependent upon antigen density and that the CAR construct in axicabtagene ciloleucel (CD19-CD28) outperforms that in tisagenlecleucel (CD19-4-1BB) against antigen-low tumors. Enhancing signal strength by including additional immunoreceptor tyrosine-based activation motifs (ITAM) in the CAR enables recognition of low-antigen-density cells, whereas ITAM deletions blunt signal and increase the antigen density threshold. Furthermore, replacement of the CD8 hinge-transmembrane (H/T) region of a 4-1BB CAR with a CD28-H/T lowers the threshold for CAR reactivity despite identical signaling molecules. CARs incorporating a CD28-H/T demonstrate a more stable and efficient immunologic synapse. Precise design of CARs can tune the threshold for antigen recognition and endow 4-1BB-CARs with enhanced capacity to recognize antigen-low targets while retaining a superior capacity for persistence.

Significance:

Optimal CAR T-cell activity is dependent on antigen density, which is variable in many cancers, including lymphoma and solid tumors. CD28-CARs outperform 4-1BB-CARs when antigen density is low. However, 4-1BB-CARs can be reengineered to enhance activity against low-antigen-density tumors while maintaining their unique capacity for persistence.

This article is highlighted in the In This Issue feature, p. 627




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Targeting HER2 with Trastuzumab Deruxtecan: A Dose-Expansion, Phase I Study in Multiple Advanced Solid Tumors [Research Articles]

HER2-targeted therapies are approved only for HER2-positive breast and gastric cancers. We assessed the safety/tolerability and activity of the novel HER2-targeted antibody–drug conjugate trastuzumab deruxtecan (T-DXd) in 60 patients with pretreated, HER2-expressing (IHC ≥ 1+), non-breast/non-gastric or HER2-mutant solid tumors from a phase I trial (NCT02564900). Most common (>50%) treatment-emergent adverse events (TEAE) were nausea, decreased appetite, and vomiting. Two drug-related TEAEs were associated with fatal outcomes. The confirmed objective response rate (ORR) was 28.3% (17/60). Median progression-free survival (PFS) was 7.2 [95% confidence interval (CI), 4.8–11.1] months. In HER2-mutant non–small cell lung cancer (NSCLC), ORR was 72.7% (8/11), and median PFS was 11.3 (95% CI, 8.1–14.3) months. Confirmed responses were observed in six tumor types, including HER2-expressing NSCLC, colorectal cancer, salivary gland cancer, biliary tract cancer, endometrial cancer, and HER2-mutant NSCLC and breast cancer. Results suggest T-DXd holds promise for HER2-expressing/mutant solid tumors.

Significance:

T-DXd demonstrated promising activity in a heterogeneous patient population with heavily pretreated HER2-expressing or HER2-mutant solid tumors, especially HER2-mutant NSCLC. The safety profile was generally acceptable. Interstitial lung disease can be severe and requires prompt monitoring and intervention. Further research of T-DXd is warranted to address these unmet medical needs.

See related commentary by Rolfo and Russo, p. 643.

This article is highlighted in the In This Issue feature, p. 627




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Decoding the Noncoding Cancer Genome [In the Spotlight]

Summary:

In this issue of Cancer Discovery, Li and colleagues provide a blueprint for the identification and functional validation of cancer-associated mutations in noncoding regions of the genome. Integration of whole-genome sequencing and high-throughput epigenome editing screens is starting to reveal the extent to which noncoding genetic lesions contribute to cancer.

See related article by Li et al., p. 724.




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Bemarituzumab Is Active in FGFR2b-High Gastroesophageal Adenocarcinoma [Clinical Trials]

The FGFR2b inhibitor bemarituzumab was effective in high-FGFR2b gastroesophageal adenocarcinoma.




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Selective Inhibition of BET Protein Domains Has Functional Relevance [Drug Development]

Inhibition of BET protein bromodomains BD1 and BD2 produces unique phenotypes in disease models.




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A Previously Unknown Dendritic Cell Type Reduces Antitumor Response [Immunology]

A cluster of dendritic cells (termed mregDCs), observed in humans and mice, restricted antitumor immunity.




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New Drug-Discovery Assay Identifies Novel Mutant-EGFR Inhibitors [Drug Discovery]

The MaMTH-DS assay detected inhibitors of mutant EGFR in non–small cell lung cancer cells.




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Cancer Labs Pivot to Battle COVID-19 [News in Depth]

As cancer researchers shutter their labs to comply with COVID-19–related work restrictions, some are turning their attention, resources, and technical know-how to the challenge of tackling the deadly coronavirus.




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Protein Instability Is Targetable in Mismatch Repair-Deficient Tumors [Research Watch]

Mismatch repair (MMR)–deficient tumors exhibit proteome-wide protein instability and aggregation.




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Study Finds Underreporting of Clinical Data [News in Brief]

Since 2018, the FDA has required that U.S. clinical trial results be reported to clinicaltrials.gov within a year of trial completion, but this mandate is often ignored. A recent study found that less than half of U.S. trials submitted results to the site by the deadline. Industry-led trials were the most likely to be reported on time.




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FDA Pushes Enrollment of Older Adults in Trials [News in Brief]

In a draft guidance, the FDA urges researchers to take steps to increase enrollment of adults age 65 and older in clinical trials of investigational of cancer drugs. Noting that a drug's risk–benefit profile can vary significantly across age groups, the FDA recommends including older adults in early-phase studies and modifying trial designs and recruitment strategies to make it easier for them to participate.




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Defining an embryonal rhabdomyosarcoma endotype [RESEARCH ARTICLE]

Rhabdomyosarcoma (RMS) is the most common childhood soft-tissue sarcoma. The largest subtype of RMS is embryonal rhabdomyosarcoma (ERMS) and accounts for 53% of all RMS. ERMS typically occurs in the head and neck region, bladder, or reproductive organs and portends a promising prognosis when localized; however, when metastatic the 5-yr overall survival rate is ~43%. The genomic landscape of ERMS demonstrates a range of putative driver mutations, and thus the recognition of the pathological mechanisms driving tumor maintenance should be critical for identifying effective targeted treatments at the level of the individual patients. Here, we report genomic, phenotypic, and bioinformatic analyses for a case of a 3-yr-old male who presented with bladder ERMS. Additionally, we use an unsupervised agglomerative clustering analysis of RNA and whole-exome sequencing data across ERMS and undifferentiated pleomorphic sarcoma (UPS) tumor samples to determine several major endotypes inferring potential targeted treatments for a spectrum of pediatric ERMS patient cases.




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[Developmental Biology] Reptiles as a Model System to Study Heart Development

A chambered heart is common to all vertebrates, but reptiles show unparalleled variation in ventricular septation, ranging from almost absent in tuataras to full in crocodilians. Because mammals and birds evolved independently from reptile lineages, studies on reptile development may yield insight into the evolution and development of the full ventricular septum. Compared with reptiles, mammals and birds have evolved several other adaptations, including compact chamber walls and a specialized conduction system. These adaptations appear to have evolved from precursor structures that can be studied in present-day reptiles. The increase in the number of studies on reptile heart development has been greatly facilitated by sequencing of several genomes and the availability of good staging systems. Here, we place reptiles in their phylogenetic context with a focus on features that are primitive when compared with the homologous features of mammals. Further, an outline of major developmental events is given, and variation between reptile species is discussed.




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[Molecular Pathology] The Formation of Coronary Vessels in Cardiac Development and Disease

Understanding how coronary blood vessels form and regenerate during development and progression of cardiac diseases will shed light on the development of new treatment options targeting coronary artery diseases. Recent studies with the state-of-the-art technologies have identified novel origins of, as well as new, cellular and molecular mechanisms underlying the formation of coronary vessels in the postnatal heart, including collateral artery formation, endocardial-to-endothelial differentiation and mesenchymal-to-endothelial transition. These new mechanisms of coronary vessel formation and regeneration open up new possibilities targeting neovascularization for promoting cardiac repair and regeneration. Here, we highlight some recent studies on cellular mechanisms of coronary vessel formation, and discuss the potential impact and significance of the findings on basic research and clinical application for treating ischemic heart disease.




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[Cell Biology] Recent Insights on Inflammasomes, Gasdermin Pores, and Pyroptosis

Inflammasomes assemble in the cytosol of myeloid and epithelial cells on sensing of cellular stress and pathogen-associated molecular patterns and serve as scaffolds for recruitment and activation of inflammatory caspases. Inflammasomes play beneficial roles in host and immune responses against diverse pathogens but may also promote inflammatory tissue damage if uncontrolled. Gasdermin D (GSDMD) is a recently identified substrate of murine caspase-1 and caspase-11, and human caspases-1, -4, and -5 that mediates a regulated lytic cell death mode termed pyroptosis. Recent studies have identified pyroptosis as a critical inflammasome effector mechanism that controls inflammasome-dependent cytokine secretion and contributes to antimicrobial defense and inflammasome-mediated autoinflammatory diseases. Here, we review recent developments on inflammasome-associated effector functions with an emphasis on the emerging roles of gasdermin pores and pyroptosis.




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[Cell Biology] Cracking the Cell Death Code

Cell death is an invariant feature throughout our life span, starting with extensive scheduled cell death during morphogenesis and continuing with death under homeostasis in adult tissues. Additionally, cells become victims of accidental, unscheduled death following injury and infection. Cell death in each of these occasions triggers specific and specialized responses in the living cells that surround them or are attracted to the dying/dead cells. These responses sculpt tissues during morphogenesis, replenish lost cells in homeostasis to maintain tissue/system function, and repair damaged tissues after injury. Wherein lies the information that sets in motion the cascade of effector responses culminating in remodeling, renewal, or repair? Here, we attempt to provide a framework for thinking about cell death in terms of the specific effector responses that accompanies various modalities of cell death. We also propose an integrated threefold "cell death code" consisting of information intrinsic to the dying/dead cell, the surroundings of the dying cell, and the identity of the responder.




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[Molecular Pathology] Toward Combined Cell and Gene Therapy for Genodermatoses

To date, more than 200 monogenic, often devastating, skin diseases have been described. Because of unmet medical needs, development of long-lasting and curative therapies has been consistently attempted, with the aim of correcting the underlying molecular defect. In this review, we will specifically address the few combined cell and gene therapy strategies that made it to the clinics. Based on these studies, what can be envisioned for the future is a patient-oriented strategy, built on the specific features of the individual in need. Most likely, a combination of different strategies, approaches, and advanced therapies will be required to reach the finish line at the end of the long and winding road hampering the achievement of definitive treatments for genodermatoses.




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Erratum. Diabetes Is Primary: Timely News and Notes for Primary Care Providers. Clinical Diabetes 2020;38:4-8 (DOI: 10.2337/cd20-dp01)




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Cleveland Clinic Foundation Internal Medicine Residency Program

Quality Improvement Success Stories are published by the American Diabetes Association in collaboration with the American College of Physicians, Inc. (ACP), and the National Diabetes Education Program. This series is intended to highlight best practices and strategies from programs and clinics that have successfully improved the quality of care for people with diabetes or related conditions. Each article in the series is reviewed and follows a standard format developed by the editors of Clinical Diabetes. The following article describes an initiative of the Cleveland Clinic’s internal medicine residents to improve diabetes care and outcomes within an underserved patient population at an East Cleveland, OH, health center.




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Distribution of Highly Prevalent Musculoskeletal Disorders and Their Association With Diabetes Complications in a Population of 140 Individuals With Type 1 Diabetes: A Retrospective Study in a French Diabetes Center

Although they are usually not considered to be diabetes complications, musculoskeletal disorders (MSKDs) are common in individuals with type 1 or type 2 diabetes and can strongly interfere with daily diabetes care, especially in people using diabetes technologies. The authors of this retrospective study in a population of 140 patients with type 1 diabetes report the distribution of subtypes of MSKDs and speculate about the mechanisms involved. The authors emphasize the need for multidisciplinary care involving not only the diabetes care team but also orthopedic surgeons. This report should lead to large, prospective studies to increase knowledge about these under-studied complications.




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Beneficial Agents for Patients With Type 2 Diabetes and Cardiovascular Disease or Obesity: Utilization in an Era of Accumulating Evidence

This study was an analysis of a national sample of U.S. medical office visits from 2014 to 2016, a period when evidence of effectiveness was emerging for a variety of beneficial type 2 diabetes agents with regard to potential reduction in diabetes comorbidities. Ideal therapy was defined as an American Diabetes Association–identified beneficial agent plus metformin. The associations between atherosclerotic cardiovascular disease or obesity and use of these agents were explored.




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&#x201C;What&#x2019;s the Point?&#x201D;: Understanding Why People With Type 2 Diabetes Decline Structured Education

Structured diabetes education (SDE) is an evidence-based intervention that supports self-management in people with type 2 diabetes. In the United Kingdom, health care providers working in primary care settings are responsible for referring people with type 2 diabetes to SDE programs. However, national audits record a high percentage of nonattenders. We explored the personal experience of living with type 2 diabetes that led to individuals declining invitations to attend SDE programs. The themes suggested that emotional, cognitive, and social issues related to diagnosis and living with diabetes may be responsible for declining to attend SDE and that these factors may be masked by explanations of practical barriers. A person-centered approach to understanding the personal meaning of being diagnosed and living with type 2 diabetes may help to identify individuals’ psychosocial barriers to attending SDE.




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Primary Care Providers in California and Florida Report Low Confidence in Providing Type 1 Diabetes Care

People with type 1 diabetes may receive a significant portion of their care from primary care providers (PCPs). To understand the involvement of PCPs in delivering type 1 diabetes care, we performed surveys in California and Florida, two of the most populous and diverse states in the United States. PCPs fill insulin prescriptions but report low confidence in providing type 1 diabetes care and difficulty accessing specialty referrals to endocrinologists.




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Timely News and Notes for Primary Care Providers from the American Diabetes Association




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Lipid Trait Variants and the Risk of Non-Hodgkin Lymphoma Subtypes: A Mendelian Randomization Study

Background:

Lipid traits have been inconsistently linked to risk of non-Hodgkin lymphoma (NHL). We examined the association of genetically predicted lipid traits with risk of diffuse large B-cell lymphoma (DLBCL), chronic lymphocytic leukemia (CLL), follicular lymphoma (FL), and marginal zone lymphoma (MZL) using Mendelian randomization (MR) analysis.

Methods:

Genome-wide association study data from the InterLymph Consortium were available for 2,661 DLBCLs, 2,179 CLLs, 2,142 FLs, 824 MZLs, and 6,221 controls. SNPs associated (P < 5 x 10–8) with high-density lipoprotein (HDL, n = 164), low-density lipoprotein (LDL, n = 137), total cholesterol (TC, n = 161), and triglycerides (TG, n = 123) were used as instrumental variables (IV), explaining 14.6%, 27.7%, 16.8%, and 12.8% of phenotypic variation, respectively. Associations between each lipid trait and NHL subtype were calculated using the MR inverse variance–weighted method, estimating odds ratios (OR) per standard deviation and 95% confidence intervals (CI).

Results:

HDL was positively associated with DLBCL (OR = 1.14; 95% CI, 1.00–1.30) and MZL (OR = 1.09; 95% CI, 1.01–1.18), while TG was inversely associated with MZL risk (OR = 0.90; 95% CI, 0.83–0.99), all at nominal significance (P < 0.05). A positive trend was observed for HDL with FL risk (OR = 1.08; 95% CI, 0.99–1.19; P = 0.087). No associations were noteworthy after adjusting for multiple testing.

Conclusions:

We did not find evidence of a clear or strong association of these lipid traits with the most common NHL subtypes. While these IVs have been previously linked to other cancers, our findings do not support any causal associations with these NHL subtypes.

Impact:

Our results suggest that prior reported inverse associations of lipid traits are not likely to be causal and could represent reverse causality or confounding.




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Race May Not Impact Endocrine Therapy-Related Changes in Breast Density

Background:

Reduction in breast density may be a biomarker of endocrine therapy (ET) efficacy. Our objective was to assess the impact of race on ET-related changes in volumetric breast density (VBD).

Methods:

This retrospective cohort study assessed longitudinal changes in VBD measures in women with estrogen receptor–positive invasive breast cancer treated with ET. VBD, the ratio of fibroglandular volume (FGV) to breast volume (BV), was measured using Volpara software. Changes in measurements were evaluated using a multivariable linear mixed effects model.

Results:

Compared with white women (n = 191), black women (n = 107) had higher rates of obesity [mean ± SD body mass index (BMI) 34.5 ± 9.1 kg/m2 vs. 30.6 ± 7.0 kg/m2, P < 0.001] and premenopausal status (32.7% vs. 16.7%, P = 0.002). Age- and BMI-adjusted baseline FGV, BV, and VBD were similar between groups. Modeled longitudinal changes were also similar: During a follow-up of 30.7 ± 15.0 months (mean ± SD), FGV decreased over time in premenopausal women (slope = –0.323 cm3; SE = 0.093; P = 0.001), BV increased overall (slope = 2.475 cm3; SE = 0.483; P < 0.0001), and VBD decreased (premenopausal slope = –0.063%, SE = 0.011; postmenopausal slope = –0.016%, SE = 0.004; P < 0.0001). Race was not significantly associated with these longitudinal changes, nor did race modify the effect of time on these changes. Higher BMI was associated with lower baseline VBD (P < 0.0001). Among premenopausal women, VBD declined more steeply for women with lower BMI (time x BMI, P = 0.0098).

Conclusions:

Race does not appear to impact ET-related longitudinal changes in VBD.

Impact:

Racial disparities in estrogen receptor–positive breast cancer recurrence and mortality may not be explained by differential declines in breast density due to ET.




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Alcohol and Tobacco Use in Relation to Mammographic Density in 23,456 Women

Background:

Percent density (PD) is a strong risk factor for breast cancer that is potentially modifiable by lifestyle factors. PD is a composite of the dense (DA) and nondense (NDA) areas of a mammogram, representing predominantly fibroglandular or fatty tissues, respectively. Alcohol and tobacco use have been associated with increased breast cancer risk. However, their effects on mammographic density (MD) phenotypes are poorly understood.

Methods:

We examined associations of alcohol and tobacco use with PD, DA, and NDA in a population-based cohort of 23,456 women screened using full-field digital mammography machines manufactured by Hologic or General Electric. MD was measured using Cumulus. Machine-specific effects were estimated using linear regression, and combined using random effects meta-analysis.

Results:

Alcohol use was positively associated with PD (Ptrend = 0.01), unassociated with DA (Ptrend = 0.23), and inversely associated with NDA (Ptrend = 0.02) adjusting for age, body mass index, reproductive factors, physical activity, and family history of breast cancer. In contrast, tobacco use was inversely associated with PD (Ptrend = 0.0008), unassociated with DA (Ptrend = 0.93), and positively associated with NDA (Ptrend<0.0001). These trends were stronger in normal and overweight women than in obese women.

Conclusions:

These findings suggest that associations of alcohol and tobacco use with PD result more from their associations with NDA than DA.

Impact:

PD and NDA may mediate the association of alcohol drinking, but not tobacco smoking, with increased breast cancer risk. Further studies are needed to elucidate the modifiable lifestyle factors that influence breast tissue composition, and the important role of the fatty tissues on breast health.




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Total Antioxidant Capacity and Pancreatic Cancer Incidence and Mortality in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial

Background:

Total antioxidant capacity (TAC) reflects an individual's overall antioxidant intake. We sought to clarify whether higher TAC is associated with lower risks of pancreatic cancer incidence and mortality in the U.S. general population.

Methods:

A total of 96,018 American adults were identified from the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial. A ferric-reducing ability of plasma score was used to reflect an individual's TAC intake from diet and/or supplements. Cox regression was used to calculate hazard ratios (HR) for pancreatic cancer incidence, and competing risk regression was used to calculate subdistribution HRs for pancreatic cancer mortality. Restricted cubic spline regression was used to test nonlinearity.

Results:

A total of 393 pancreatic cancer cases and 353 pancreatic cancer–related deaths were documented. Total (diet + supplements) TAC was found to be inversely associated with pancreatic cancer incidence (HR quartile 4 vs. quartile 1 = 0.53; 95% confidence interval, 0.39–0.72; Ptrend = 0.0002) and mortality (subdistribution HR quartile 4 vs. quartile 1 = 0.52; 95% confidence interval 0.38–0.72; Ptrend = 0.0003) in a nonlinear dose–response manner (all Pnonlinearity < 0.01). Similar results were observed for dietary TAC. No association of supplemental TAC with pancreatic cancer incidence and mortality was found.

Conclusions:

In the U.S. general population, dietary but not supplemental TAC level is inversely associated with risks of pancreatic cancer incidence and mortality in a nonlinear dose–response pattern.

Impact:

This is the first prospective study indicating that a diet rich in antioxidants may be beneficial in decreasing pancreatic cancer incidence and mortality.




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Serum PIWI-Interacting RNAs piR-020619 and piR-020450 Are Promising Novel Biomarkers for Early Detection of Colorectal Cancer

Background:

Early diagnosis can significantly reduce colorectal cancer deaths. We sought to identify serum PIWI-interacting RNAs (piRNAs) that could serve as sensitive and specific noninvasive biomarkers for early colorectal cancer detection.

Methods:

We screened the piRNA expression profile in sera from 7 patients with colorectal cancer and 7 normal controls using small RNA sequencing. Differentially expressed piRNAs were measured in a training cohort of 140 patients with colorectal cancer and 140 normal controls using reverse transcription quantitative PCR. The identified piRNAs were evaluated in two independent validation cohorts of 180 patients with colorectal cancer and 180 normal controls. Finally, the diagnostic value of the identified piRNAs for colorectal adenoma (CRA) was assessed, and their expression was measured in 50 patients with lung cancer, 50 with breast cancer, and 50 with gastric cancer.

Results:

The piRNAs piR-020619 and piR-020450 were consistently elevated in sera of patients with colorectal cancer as compared with controls. A predicative panel based on the two piRNAs was established that displayed high diagnostic accuracy for colorectal cancer detection. The two-piRNA panel could detect small-size and early-stage colorectal cancer with an area under the ROC curve of 0.863 and 0.839, respectively. Combined use of the two piRNAs could effectively distinguish CRA from controls. Aberrant elevation of the two piRNAs was not observed in sera of patients with lung, breast, and gastric cancer.

Conclusions:

Serum piR-020619 and piR-020450 show a strong potential as colorectal cancer-specific early detection biomarkers.

Impact:

The field of circulating piRNAs could allow for novel tumor biomarker development.




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Circulating Biomarker Score for Visceral Fat and Risks of Incident Colorectal and Postmenopausal Breast Cancer: The Multiethnic Cohort Adiposity Phenotype Study

Background:

Visceral adipose tissue (VAT) may play a greater role than subcutaneous fat in increasing cancer risk but is poorly estimated in epidemiologic studies.

Methods:

We developed a VAT prediction score by regression equations averaged across 100 least absolute shrinkage and selection operator models in a cross-sectional study of 1,801 older adults in the Multiethnic Cohort (MEC). The score was then used as proxy for VAT in case–control studies of postmenopausal breast (950 case–control pairs) and colorectal (831 case–control pairs) cancer in an independent sample in MEC. Abdominal MRI–derived VAT; circulating biomarkers of metabolic, hormonal, and inflammation dysfunctions; and ORs for incident cancer adjusted for BMI and other risk factors were assessed.

Results:

The final score, composed of nine biomarkers, BMI, and height, explained 11% and 15% more of the variance in VAT than BMI alone in men and women, respectively. The area under the receiver operator curve for VAT >150 cm2 was 0.90 in men and 0.86 in women. The VAT score was associated with risk of breast cancer [OR (95% confidence interval [CI]) by increasing tertiles: 1.00, 1.09 (0.86–1.39), 1.48 (1.16–1.89); Ptrend = 0.002] but not with colorectal cancer (P = 0.84), although an association [1.00, 0.98 (0.68–1.39), 1.24 (0.88–1.76); Ptrend = 0.08] was suggested for this cancer after excluding cases that occurred within 7 years of blood draw (Pheterogeneity = 0.06).

Conclusions:

The VAT score predicted risks of postmenopausal breast cancer and can be used for risk assessment in diverse populations.

Impact:

These findings provide specific evidence for a role of VAT in breast cancer.




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Li-Fraumeni Exploration Consortium Data Coordinating Center: Building an Interactive Web-Based Resource for Collaborative International Cancer Epidemiology Research for a Rare Condition

Background:

The success of multisite collaborative research relies on effective data collection, harmonization, and aggregation strategies. Data Coordination Centers (DCC) serve to facilitate the implementation of these strategies. The utility of a DCC can be particularly relevant for research on rare diseases where collaboration from multiple sites to amass large aggregate datasets is essential. However, approaches to building a DCC have been scarcely documented.

Methods:

The Li-Fraumeni Exploration (LiFE) Consortium's DCC was created using multiple open source packages, including LAM/G Application (Linux, Apache, MySQL, Grails), Extraction-Transformation-Loading (ETL) Pentaho Data Integration Tool, and the Saiku-Mondrian client. This document serves as a resource for building a rare disease DCC for multi-institutional collaborative research.

Results:

The primary scientific and technological objective to create an online central repository into which data from all participating sites could be deposited, harmonized, aggregated, disseminated, and analyzed was completed. The cohort now include 2,193 participants from six contributing sites, including 1,354 individuals from families with a pathogenic or likely variant in TP53. Data on cancer diagnoses are also available. Challenges and lessons learned are summarized.

Conclusions:

The methods leveraged mitigate challenges associated with successfully developing a DCC's technical infrastructure, data harmonization efforts, communications, and software development and applications.

Impact:

These methods can serve as a framework in establishing other collaborative research efforts. Data from the consortium will serve as a great resource for collaborative research to improve knowledge on, and the ability to care for, individuals and families with Li-Fraumeni syndrome.