b Early Bactericidal Activity Trial of Nitazoxanide for Pulmonary Tuberculosis [Clinical Therapeutics] By aac.asm.org Published On :: 2020-04-21T08:01:09-07:00 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.) Full Article
b Activity of Cefiderocol and Comparators against Isolates from Cancer Patients [Susceptibility] By aac.asm.org Published On :: 2020-04-21T08:01:09-07:00 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. Full Article
b Abacavir Exposure in Children Cotreated for Tuberculosis with Rifampin and Superboosted Lopinavir-Ritonavir [Pharmacology] By aac.asm.org Published On :: 2020-04-21T08:01:09-07:00 In children requiring lopinavir coformulated with ritonavir in a 4:1 ratio (lopinavir-ritonavir-4:1) and rifampin, adding ritonavir to achieve a 4:4 ratio with lopinavir (LPV/r-4:4) overcomes the drug-drug interaction. Possible drug-drug interactions within this regimen may affect abacavir concentrations, but this has never been studied. Children weighing <15 kg needing rifampin and LPV/r-4:4 were enrolled in a pharmacokinetic study and underwent intensive pharmacokinetic sampling on 3 visits: (i) during the intensive and (ii) continuation phases of antituberculosis treatment with LPV/r-4:4 and (iii) 1 month after antituberculosis treatment completion on LPV/r-4:1. Pharmacometric modeling and simulation were used to compare exposures across weight bands with adult target exposures. Eighty-seven children with a median (interquartile range) age and weight of 19 (4 to 64) months and 8.7 (3.9 to 14.9) kg, respectively, were included in the abacavir analysis. Abacavir pharmacokinetics were best described by a two-compartment model with first-order elimination and transit compartment absorption. After allometric scaling adjusted for the effect of body size, maturation could be identified: clearance was predicted to be fully mature at about 2 years of age and to reach half of this mature value at about 2 months of age. Abacavir bioavailability decreased 36% during treatment with rifampin and LPV/r-4:4 but remained within the median adult recommended exposure, except for children in the 3- to 4.9-kg weight band, in which the exposures were higher. The observed predose morning trough concentrations were higher than the evening values. Though abacavir exposure significantly decreased during concomitant administration of rifampin and LPV/r-4:4, it remained within acceptable ranges. (This study is registered in ClinicalTrials.gov under identifier NCT02348177.) Full Article
b Antiviral Activity of a Llama-Derived Single-Domain Antibody against Enterovirus A71 [Antiviral Agents] By aac.asm.org Published On :: 2020-04-21T08:01:09-07:00 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. Full Article
b Drug Effect of Clofazimine on Persisters Explains an Unexpected Increase in Bacterial Load in Patients [Pharmacology] By aac.asm.org Published On :: 2020-04-21T08:01:09-07:00 Antituberculosis (anti-TB) drug development is dependent on informative trials to secure the development of new antibiotics and combination regimens. Clofazimine (CLO) and pyrazinamide (PZA) are important components of recommended standard multidrug treatments of TB. Paradoxically, in a phase IIa trial aiming to define the early bactericidal activity (EBA) of CLO and PZA monotherapy over the first 14 days of treatment, no significant drug effect was demonstrated for the two drugs using traditional statistical analysis. Using a model-based analysis, we characterized the statistically significant exposure-response relationships for both drugs that could explain the original findings of an increase in the numbers of CFU with CLO treatment and no effect with PZA. Sensitive analyses are crucial for exploring drug effects in early clinical trials to make the right decisions for advancement to further development. We propose that this quantitative semimechanistic approach provides a rational framework for analyzing phase IIa EBA studies and can accelerate anti-TB drug development. Full Article
b Whole-Cell Phenotypic Screening of Medicines for Malaria Venture Pathogen Box Identifies Specific Inhibitors of Plasmodium falciparum Late-Stage Development and Egress [Experimental Therapeutics] By aac.asm.org Published On :: 2020-04-21T08:01:09-07:00 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. Full Article
b Adduct Formation of Delamanid with NAD in Mycobacteria [Mechanisms of Action] By aac.asm.org Published On :: 2020-04-21T08:01:09-07:00 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. Full Article
b Erratum for Asempa et al., "In Vitro Activity of Imipenem-Relebactam Alone or in Combination with Amikacin or Colistin against Pseudomonas aeruginosa" [Errata] By aac.asm.org Published On :: 2020-04-21T08:01:09-07:00 Full Article
b Tilorone, a Broad-Spectrum Antiviral for Emerging Viruses [Antiviral Agents] By aac.asm.org Published On :: 2020-04-21T08:01:09-07:00 Tilorone is a 50-year-old synthetic small-molecule compound with antiviral activity that is proposed to induce interferon after oral administration. This drug is used as a broad-spectrum antiviral in several countries of the Russian Federation. We have recently described activity in vitro and in vivo against the Ebola virus. After a broad screening of additional viruses, we now describe in vitro activity against Chikungunya virus (CHIK) and Middle Eastern respiratory syndrome coronavirus (MERS-CoV). Full Article
b Distinct Mechanisms of Dissemination of NDM-1 Metallo-{beta}-Lactamase in Acinetobacter Species in Argentina [Epidemiology and Surveillance] By aac.asm.org Published On :: 2020-04-21T08:01:09-07:00 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. Full Article
b Whole-Genome Characterization of a Shewanella algae Strain Coharboring blaCTX-M-15 and armA Genes on a Novel IncC Plasmid [Letters] By aac.asm.org Published On :: 2020-04-21T08:01:09-07:00 Full Article
b Enhanced Efflux Pump Expression in Candida Mutants Results in Decreased Manogepix Susceptibility [Mechanisms of Resistance] By aac.asm.org Published On :: 2020-04-21T08:01:09-07:00 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. Full Article
b Dose Optimization of Cefpirome Based on Population Pharmacokinetics and Target Attainment during Extracorporeal Membrane Oxygenation [Clinical Therapeutics] By aac.asm.org Published On :: 2020-04-21T08:01:09-07:00 To obtain the optimal dosage regimen in patients receiving extracorporeal membrane oxygenation (ECMO), we developed a population pharmacokinetics model for cefpirome and performed pharmacodynamic analyses. This prospective study included 15 patients treated with cefpirome during ECMO. Blood samples were collected during ECMO (ECMO-ON) and after ECMO (ECMO-OFF) at predose and 0.5 to 1, 2 to 3, 4 to 6, 8 to 10, and 12 h after cefpirome administration. The population pharmacokinetic model was developed using nonlinear mixed effects modeling and stepwise covariate modeling. Monte Carlo simulation was used to assess the probability of target attainment (PTA) and cumulative fraction of response (CFR) according to the MIC distribution. Cefpirome pharmacokinetics were best described by a two-compartment model. Covariate analysis indicated that serum creatinine concentration (SCr) was negatively correlated with clearance, and the presence of ECMO increased clearance and the central volume of distribution. The simulations showed that patients with low SCr during ECMO-ON had lower PTA than patients with high SCr during ECMO-OFF; so, a higher dosage of cefpirome was required. Cefpirome of 2 g every 8 h for intravenous bolus injection or 2 g every 12 h for extended infusion over 4 h was recommended with normal kidney function receiving ECMO. We established a population pharmacokinetic model for cefpirome in patients with ECMO, and appropriate cefpirome dosage regimens were recommended. The impact of ECMO could be due to the change in patient status on consideration of the small population and uncertainty in covariate relationships. Dose optimization of cefpirome may improve treatment success and survival in patients receiving ECMO. (This study has been registered at ClinicalTrials.gov under identifier NCT02581280.) Full Article
b Antimicrobial Activity of Ceftolozane-Tazobactam and Comparators against Clinical Isolates of Haemophilus influenzae from the United States and Europe [Susceptibility] By aac.asm.org Published On :: 2020-04-21T08:01:09-07:00 Nine hundred Haemophilus influenzae clinical isolates from 83 U.S. and European medical centers were tested for susceptibility by reference broth microdilution methods against ceftolozane-tazobactam and comparators. Results were stratified by β-lactamase production and infection type. Overall, ceftolozane-tazobactam MIC50/90 values were 0.12/0.25 mg/liter, and 99.0% of isolates were inhibited at the susceptible breakpoint of ≤0.5 mg/liter; the highest MIC value was only 2 mg/liter. Our results support using ceftolozane-tazobactam to treat H. influenzae infections. Full Article
b 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] By aac.asm.org Published On :: 2020-04-21T08:01:09-07:00 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. Full Article
b Predominant Distribution of OXA-48-Like Carbapenemase in Fecal Colonization [Letters] By aac.asm.org Published On :: 2020-04-21T08:01:09-07:00 Full Article
b Molecular and Clinical Characterization of Multidrug-Resistant and Hypervirulent Klebsiella pneumoniae Strains from Liver Abscess in Taiwan [Epidemiology and Surveillance] By aac.asm.org Published On :: 2020-04-21T08:01:09-07:00 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. Full Article
b Unorthodox Parenteral {beta}-Lactam and {beta}-Lactamase Inhibitor Combinations: Flouting Antimicrobial Stewardship and Compromising Patient Care [Commentary] By aac.asm.org Published On :: 2020-04-21T08:01:09-07:00 In India and China, indigenous drug manufacturers market arbitrarily combined parenteral β-lactam and β-lactamase inhibitors (BL-BLIs). In these fixed-dose combinations, sulbactam or tazobactam is indiscriminately combined with parenteral cephalosporins, with BLI doses kept in ratios similar to those for the approved BL-BLIs. Such combinations have been introduced into clinical practice without mandatory drug development studies involving pharmacokinetic/pharmacodynamic, safety, and efficacy assessments being undertaken. Such unorthodox combinations compromise clinical outcomes and also potentially contribute to resistance development. Full Article
b ISEcp1-Mediated Transposition Leads to Fosfomycin and Broad-Spectrum Cephalosporin Resistance in Klebsiella pneumoniae [Mechanisms of Resistance] By aac.asm.org Published On :: 2020-04-21T08:01:09-07:00 A fosfomycin-resistant and carbapenemase (OXA-48)-producing Klebsiella pneumoniae isolate was recovered, and whole-genome sequencing revealed ISEcp1-blaCTX-M-14b tandemly inserted upstream of the chromosomally encoded lysR-fosA locus. Quantitative evaluation of the expression of lysR and fosA genes showed that this insertion brought a strong hybrid promoter leading to overexpression of the fosA gene, resulting in fosfomycin resistance. This work showed the concomitant acquisition of resistance to broad-spectrum cephalosporins and fosfomycin due to a single genetic event. Full Article
b Structural Insights into Ceftobiprole Inhibition of Pseudomonas aeruginosa Penicillin-Binding Protein 3 [Experimental Therapeutics] By aac.asm.org Published On :: 2020-04-21T08:01:09-07:00 Ceftobiprole is an advanced-generation broad-spectrum cephalosporin antibiotic with potent and rapid bactericidal activity against Gram-positive pathogens, including methicillin-resistant Staphylococcus aureus, as well as susceptible Gram-negative pathogens, including Pseudomonas sp. pathogens. In the case of Pseudomonas aeruginosa, ceftobiprole acts by inhibiting P. aeruginosa penicillin-binding protein 3 (PBP3). Structural studies were pursued to elucidate the molecular details of this PBP inhibition. The crystal structure of the His-tagged PBP3-ceftobiprole complex revealed a covalent bond between the ligand and the catalytic residue S294. Ceftobiprole binding leads to large active site changes near binding sites for the pyrrolidinone and pyrrolidine rings. The S528 to L536 region adopts a conformation previously not observed in PBP3, including partial unwinding of the α11 helix. These molecular insights can lead to a deeper understanding of β-lactam-PBP interactions that result in major changes in protein structure, as well as suggesting how to fine-tune current inhibitors and to develop novel inhibitors of this PBP. Full Article
b Levonadifloxacin, a Novel Benzoquinolizine Fluoroquinolone, Modulates Lipopolysaccharide-Induced Inflammatory Responses in Human Whole-Blood Assay and Murine Acute Lung Injury Model [Pharmacology] By aac.asm.org Published On :: 2020-04-21T08:01:09-07:00 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. Full Article
b Encephalitozoon cuniculi Genotype III Evinces a Resistance to Albendazole Treatment in both Immunodeficient and Immunocompetent Mice [Experimental Therapeutics] By aac.asm.org Published On :: 2020-04-21T08:01:09-07:00 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. Full Article
b Accumulation of Major Linezolid Metabolites in Patients with Renal Impairment [Pharmacology] By aac.asm.org Published On :: 2020-04-21T08:01:09-07:00 In patients with renal impairment (n = 22 of 39), the median serum concentrations of linezolid, PNU-142300, and PNU-142586 were 1.6-, 3.3-, 2.8-fold higher, respectively, than in patients without renal impairment. Metabolite concentrations in paired samples were poorly correlated with linezolid concentrations (r2 = 0.26 for PNU-142300 and 0.06 for PNU-142586). Linezolid and its metabolites share potential toxicophores that deserve characterization to mitigate higher myelosuppression risk in patients with renal impairment. Full Article
b ARGONAUT II Study of the In Vitro Activity of Plazomicin against Carbapenemase-Producing Klebsiella pneumoniae [Mechanisms of Resistance] By aac.asm.org Published On :: 2020-04-21T08:01:09-07:00 Plazomicin was tested against 697 recently acquired carbapenem-resistant Klebsiella pneumoniae isolates from the Great Lakes region of the United States. Plazomicin MIC50 and MIC90 values were 0.25 and 1 mg/liter, respectively; 680 isolates (97.6%) were susceptible (MICs of ≤2 mg/liter), 9 (1.3%) intermediate (MICs of 4 mg/liter), and 8 (1.1%) resistant (MICs of >32 mg/liter). Resistance was associated with rmtF-, rmtB-, or armA-encoded 16S rRNA methyltransferases in all except 1 isolate. Full Article
b Insecticidal Activity of Doxycycline against the Common Bedbug [Experimental Therapeutics] By aac.asm.org Published On :: 2020-04-21T08:01:09-07:00 There is an ongoing need for safe and effective anti-bedbug compounds. Here, we tested the toxicity of three antimicrobial agents against bedbugs when administered orally. We reveal that doxycycline has direct insecticidal activity at 250 μg/ml (0.025%) that is particularly strong against immature bedbugs and appears to be independent of antimicrobial activity. Future studies to determine the mechanisms behind this property could be useful for the development of orally active insecticides or anti-bedbug therapeutics. Full Article
b Correction: Senescence Sensitivity of Breast Cancer Cells Is Defined by Positive Feedback Loop between CIP2A and E2F1 [Correction] By cancerdiscovery.aacrjournals.org Published On :: 2020-05-01T00:05:26-07:00 Full Article
b Targeting HER2 with Trastuzumab Deruxtecan: A Dose-Expansion, Phase I Study in Multiple Advanced Solid Tumors [Research Articles] By cancerdiscovery.aacrjournals.org Published On :: 2020-05-01T00:05:26-07:00 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 Full Article
b HER2-Mediated Internalization of Cytotoxic Agents in ERBB2 Amplified or Mutant Lung Cancers [Research Articles] By cancerdiscovery.aacrjournals.org Published On :: 2020-05-01T00:05:26-07:00 Amplification of and oncogenic mutations in ERBB2, the gene encoding the HER2 receptor tyrosine kinase, promote receptor hyperactivation and tumor growth. Here we demonstrate that HER2 ubiquitination and internalization, rather than its overexpression, are key mechanisms underlying endocytosis and consequent efficacy of the anti-HER2 antibody–drug conjugates (ADC) ado-trastuzumab emtansine (T-DM1) and trastuzumab deruxtecan (T-DXd) in lung cancer cell lines and patient-derived xenograft models. These data translated into a 51% response rate in a clinical trial of T-DM1 in 49 patients with ERBB2-amplified or -mutant lung cancers. We show that cotreatment with irreversible pan-HER inhibitors enhances receptor ubiquitination and consequent ADC internalization and efficacy. We also demonstrate that ADC switching to T-DXd, which harbors a different cytotoxic payload, achieves durable responses in a patient with lung cancer and corresponding xenograft model developing resistance to T-DM1. Our findings may help guide future clinical trials and expand the field of ADC as cancer therapy. Significance: T-DM1 is clinically effective in lung cancers with amplification of or mutations in ERBB2. This activity is enhanced by cotreatment with irreversible pan-HER inhibitors, or ADC switching to T-DXd. These results may help address unmet needs of patients with HER2-activated tumors and no approved targeted therapy. See related commentary by Rolfo and Russo, p. 643. This article is highlighted in the In This Issue feature, p. 627 Full Article
b Plasma DNA End-Motif Profiling as a Fragmentomic Marker in Cancer, Pregnancy, and Transplantation [Research Briefs] By cancerdiscovery.aacrjournals.org Published On :: 2020-05-01T00:05:26-07:00 Plasma DNA fragmentomics is an emerging area of research covering plasma DNA sizes, end points, and nucleosome footprints. In the present study, we found a significant increase in the diversity of plasma DNA end motifs in patients with hepatocellular carcinoma (HCC). Compared with patients without HCC, patients with HCC showed a preferential pattern of 4-mer end motifs. In particular, the abundance of plasma DNA motif CCCA was much lower in patients with HCC than in subjects without HCC. The aberrant end motifs were also observed in patients with other cancer types, including colorectal cancer, lung cancer, nasopharyngeal carcinoma, and head and neck squamous cell carcinoma. We further observed that the profile of plasma DNA end motifs originating from the same organ, such as the liver, placenta, and hematopoietic cells, generally clustered together. The profile of end motifs may therefore serve as a class of biomarkers for liquid biopsy in oncology, noninvasive prenatal testing, and transplantation monitoring. Significance: Plasma DNA molecules originating from the liver, HCC and other cancers, placenta, and hematopoietic cells each harbor a set of characteristic plasma DNA end motifs. Such markers carry tissue-of-origin information and represent a new class of biomarkers in the nascent field of fragmentomics. This article is highlighted in the In This Issue feature, p. 627 Full Article
b Pan-Cancer Efficacy of Vemurafenib in BRAFV600-Mutant Non-Melanoma Cancers [Research Briefs] By cancerdiscovery.aacrjournals.org Published On :: 2020-05-01T00:05:26-07:00 BRAFV600 mutations occur in a wide range of tumor types, and RAF inhibition has become standard in several of these cancers. Despite this progress, BRAFV600 mutations have historically been considered a clear demonstration of tumor lineage context–dependent oncogene addiction, based predominantly on the insensitivity to RAF inhibition in colorectal cancer. However, the true broader activity of RAF inhibition pan-cancer remains incompletely understood. To address this, we conducted a multicohort "basket" study of the BRAF inhibitor vemurafenib in non-melanoma BRAFV600 mutation–positive solid tumors. In total, 172 patients with 26 unique cancer types were treated, achieving an overall response rate of 33% and median duration of response of 13 months. Responses were observed in 13 unique cancer types, including historically treatment-refractory tumor types such as cholangiocarcinoma, sarcoma, glioma, neuroendocrine carcinoma, and salivary gland carcinomas. Collectively, these data demonstrate that single-agent BRAF inhibition has broader clinical activity than previously recognized. Significance: These data suggest that BRAFV600 mutations lead to oncogene addiction and are clinically actionable in a broad range of non-melanoma cancers, including tumor types in which RAF inhibition is not currently considered standard of care. See related commentary by Ribas and Lo, p. 640. This article is highlighted in the In This Issue feature, p. 627 Full Article
b Fibroblast Heterogeneity in the Pancreatic Tumor Microenvironment [Mini Review] By cancerdiscovery.aacrjournals.org Published On :: 2020-05-01T00:05:26-07:00 The poor prognosis for patients with pancreatic ductal adenocarcinoma (PDAC) impels an improved understanding of disease biology to facilitate the development of better therapies. PDAC typically features a remarkably dense stromal reaction, featuring and established by a prominent population of cancer-associated fibroblasts (CAF). Genetically engineered mouse models and increasingly sophisticated cell culture techniques have demonstrated important roles for fibroblasts in PDAC progression and therapy response, but these roles are complex, with strong evidence for both tumor-supportive and tumor-suppressive or homeostatic functions. Here, we review the recent literature that has improved our understanding of heterogeneity in fibroblast fate and function in this disease including the existence of distinct fibroblast populations, and highlight important avenues for future study. Significance: Although the abundant stromal reaction associated with pancreatic cancer has long been appreciated, the functions of the CAF cells that establish this stromal reaction remain unclear. An improved understanding of the transcriptional and functional heterogeneity of pancreatic CAFs, as well as their tumor-supportive versus tumor-suppressive capacity, may facilitate the development of effective therapies for this disease. Full Article
b Trying for a BRAF Slam Dunk [In the Spotlight] By cancerdiscovery.aacrjournals.org Published On :: 2020-05-01T00:05:26-07:00 Summary: The first basket clinical trial testing the BRAF inhibitor vemurafenib resulted in evidence of activity in 13 unique cancer types with BRAFV600 mutations, but the response rates were variable. Therefore, different cancer histologies with the same driver oncogene display different degrees of oncogenic pathway addiction. See related article by Subbiah et al., p. 657. Full Article
b Pemigatinib Is Active in Some FGFR2-Altered Cholangiocarcinomas [Clinical Trials] By cancerdiscovery.aacrjournals.org Published On :: 2020-05-01T00:05:26-07:00 Pemigatinib was effective in patients with cholangiocarcinomas with FGFR2 fusions or rearrangements. Full Article
b Somatic Copy-Number Alterations Contribute to Brain Metastasis [Metastasis] By cancerdiscovery.aacrjournals.org Published On :: 2020-05-01T00:05:26-07:00 In lung cancer, brain metastasis was associated with somatic amplification of MYC, YAP1, or MMP13. Full Article
b Bemarituzumab Is Active in FGFR2b-High Gastroesophageal Adenocarcinoma [Clinical Trials] By cancerdiscovery.aacrjournals.org Published On :: 2020-05-01T00:05:26-07:00 The FGFR2b inhibitor bemarituzumab was effective in high-FGFR2b gastroesophageal adenocarcinoma. Full Article
b Selective Inhibition of BET Protein Domains Has Functional Relevance [Drug Development] By cancerdiscovery.aacrjournals.org Published On :: 2020-05-01T00:05:26-07:00 Inhibition of BET protein bromodomains BD1 and BD2 produces unique phenotypes in disease models. Full Article
b Strong HPV Vaccine Response Predicts Better Survival with Chemotherapy [Clinical Trials] By cancerdiscovery.aacrjournals.org Published On :: 2020-05-01T00:05:26-07:00 Patients with HPV16+ cervical cancer and high T-cell responses to an HPV16 vaccine survived longer. Full Article
b New Drug-Discovery Assay Identifies Novel Mutant-EGFR Inhibitors [Drug Discovery] By cancerdiscovery.aacrjournals.org Published On :: 2020-05-01T00:05:26-07:00 The MaMTH-DS assay detected inhibitors of mutant EGFR in non–small cell lung cancer cells. Full Article
b Colibactin Causes Colorectal Cancer-Associated Mutational Signature [Microbiome] By cancerdiscovery.aacrjournals.org Published On :: 2020-05-01T00:05:26-07:00 The pks+ E. coli metabolite colibactin caused a unique mutational signature in intestinal organoids. Full Article
b Cancer Labs Pivot to Battle COVID-19 [News in Depth] By cancerdiscovery.aacrjournals.org Published On :: 2020-05-01T00:05:26-07:00 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. Full Article
b Noted [News in Brief] By cancerdiscovery.aacrjournals.org Published On :: 2020-05-01T00:05:26-07:00 A collection of recently published news items. Full Article
b Microbiome Predicts Blood-Cell Transplant Success [News in Brief] By cancerdiscovery.aacrjournals.org Published On :: 2020-05-01T00:05:26-07:00 A large international study found that the composition of the intestinal microbiome can predict clinical outcomes in patients undergoing allogenic hematopoietic-cell transplant (HCT) for blood cancers. The findings may help assess patients' transplantation-related mortality risk and aid in developing interventions to prevent or mitigate microbiome changes that affect HCT outcomes. Full Article
b Looking to Scorpion Venom for GBM Treatment [News in Brief] By cancerdiscovery.aacrjournals.org Published On :: 2020-05-01T00:05:26-07:00 Chlorotoxin, a small peptide component of scorpion venom, may help pinpoint glioblastoma cells for destruction when engineered into a chimeric antigen receptor T-cell therapy. The concept has shown efficacy in mice, without off-target toxicity, and will soon be assessed in patients. Full Article
b CAR Engineering Comes to Macrophages [News in Brief] By cancerdiscovery.aacrjournals.org Published On :: 2020-05-01T00:05:26-07:00 Human macrophages equipped with chimeric antigen receptor constructs infiltrate solid tumors, ingest malignant tissue, and stimulate adaptive immunity in mouse models. Several new biotech companies are racing to bring the technology into clinical trials. Full Article
b Thermo to Buy Qiagen for $11.5 Billion [News in Brief] By cancerdiscovery.aacrjournals.org Published On :: 2020-05-01T00:05:26-07:00 Thermo Fisher Scientific announced plans in March to acquire Qiagen in a $11.5 billion deal that could bring morediagnostic offeringsand sample-preparation technologies to one of the world's leading manufacturers of scientific instruments, research services, and laboratory consumables. Full Article
b Clinical Research Slows as COVID-19 Surges [News in Brief] By cancerdiscovery.aacrjournals.org Published On :: 2020-05-01T00:05:26-07:00 As the COVID-19 pandemic worsens, the clinical cancer community is grappling with how to continue providing access to experimental but potentially lifesaving therapies while keeping immunocompromised patients safe. To that end, cancer centers are making changes to their clinical trial programs, while pharmaceutical companies are deciding how—or whether—trials should continue. Full Article
b People [News in Brief] By cancerdiscovery.aacrjournals.org Published On :: 2020-05-01T00:05:26-07:00 Antoni Ribas, MD, PhD, and Gillian Leng, MBChB, are featured. Full Article
b Method Enables Nanoscale Mapping of Protein Interactions on Live Cells [Techniques] By cancerdiscovery.aacrjournals.org Published On :: 2020-05-01T00:05:26-07:00 A new method called MicroMapping can identify nanoscale protein–protein interactions on live cells. Full Article
b Ubiquitination Causes Fanconi Anemia-Linked ID Complex Ring Formation [Structural Biology] By cancerdiscovery.aacrjournals.org Published On :: 2020-05-01T00:05:26-07:00 Monoubiquitinated FANCI and FANCD2 constitute the ID complex, which forms a sliding clamp on DNA. Full Article