vi Antifungal Susceptibility Testing: Current Approaches [Reviews] By cmr.asm.org Published On :: 2020-04-29T05:33:50-07:00 Although not as ubiquitous as antibacterial susceptibility testing, antifungal susceptibility testing (AFST) is a tool of increasing importance in clinical microbiology laboratories. The goal of AFST is to reliably produce MIC values that may be used to guide patient therapy, inform epidemiological studies, and track rates of antifungal drug resistance. There are three methods that have been standardized by standards development organizations: broth dilution, disk diffusion, and azole agar screening for Aspergillus. Other commonly used methods include gradient diffusion and the use of rapid automated instruments. Novel methodologies for susceptibility testing are in development. It is important for laboratories to consider not only the method of testing but also the interpretation (or lack thereof) of in vitro data. Full Article
vi Correction: EGFR Exon 20 Insertion Mutations Display Sensitivity to Hsp90 Inhibition in Preclinical Models and Lung Adenocarcinomas By clincancerres.aacrjournals.org Published On :: 2020-05-01T00:05:37-07:00 Full Article
vi Association of Anti-TNF with Decreased Survival in Steroid Refractory Ipilimumab and Anti-PD1-Treated Patients in the Dutch Melanoma Treatment Registry By clincancerres.aacrjournals.org Published On :: 2020-05-01T00:05:36-07:00 Purpose: Unleashing the immune system by PD-1 and/or CTLA-4 blockade can cause severe immune-related toxicity necessitating immunosuppressive treatment. Whether immunosuppression for toxicity impacts survival is largely unknown. Experimental Design: Using data from the prospective nationwide Dutch Melanoma Treatment Registry (DMTR), we analyzed the association between severe toxicity and overall survival (OS) in 1,250 patients with advanced melanoma who were treated with immune checkpoint inhibitors (ICI) in first line between 2012 and 2017. Furthermore, we analyzed whether toxicity management affected survival in these patients. Results: A total of 1,250 patients were included, of whom 589 received anti-PD1 monotherapy, 576 ipilimumab, and 85 combination therapy. A total of 312 patients (25%) developed severe (grade ≥3) toxicity. Patients experiencing severe ICI toxicity had a significantly prolonged survival with a median OS of 23 months compared with 15 months for patients without severe toxicity [hazard ratio (HRadj) = 0.77; 95% confidence interval (CI), 0.63–0.93]. Among patients experiencing severe toxicity, survival was significantly decreased in patients who received anti-TNF ± steroids for steroid-refractory toxicity compared with patients who were managed with steroids only (HRadj = 1.61; 95% CI, 1.03–2.51), with a median OS of 17 and 27 months, respectively. Conclusions: Patients experiencing severe ICI toxicity have a prolonged OS. However, this survival advantage is abrogated when anti-TNF is administered for steroid-refractory toxicity. Further prospective studies are needed to assess the effect of different immunosuppressive regimens on checkpoint inhibitor efficacy. See related commentary by Weber and Postow, p. 2085 Full Article
vi Surfactant Expression Defines an Inflamed Subtype of Lung Adenocarcinoma Brain Metastases that Correlates with Prolonged Survival By clincancerres.aacrjournals.org Published On :: 2020-05-01T00:05:36-07:00 Purpose: To provide a better understanding of the interplay between the immune system and brain metastases to advance therapeutic options for this life-threatening disease. Experimental Design: Tumor-infiltrating lymphocytes (TIL) were quantified by semiautomated whole-slide analysis in brain metastases from 81 lung adenocarcinomas. Multi-color staining enabled phenotyping of TILs (CD3, CD8, and FOXP3) on a single-cell resolution. Molecular determinants of the extent of TILs in brain metastases were analyzed by transcriptomics in a subset of 63 patients. Findings in lung adenocarcinoma brain metastases were related to published multi-omic primary lung adenocarcinoma The Cancer Genome Atlas data (n = 230) and single-cell RNA-sequencing (scRNA-seq) data (n = 52,698). Results: TIL numbers within tumor islands was an independent prognostic marker in patients with lung adenocarcinoma brain metastases. Comparative transcriptomics revealed that expression of three surfactant metabolism-related genes (SFTPA1, SFTPB, and NAPSA) was closely associated with TIL numbers. Their expression was not only prognostic in brain metastasis but also in primary lung adenocarcinoma. Correlation with scRNA-seq data revealed that brain metastases with high expression of surfactant genes might originate from tumor cells resembling alveolar type 2 cells. Methylome-based estimation of immune cell fractions in primary lung adenocarcinoma confirmed a positive association between lymphocyte infiltration and surfactant expression. Tumors with a high surfactant expression displayed a transcriptomic profile of an inflammatory microenvironment. Conclusions: The expression of surfactant metabolism-related genes (SFTPA1, SFTPB, and NAPSA) defines an inflamed subtype of lung adenocarcinoma brain metastases characterized by high abundance of TILs in close vicinity to tumor cells, a prolonged survival, and a tumor microenvironment which might be more accessible to immunotherapeutic approaches. Full Article
vi Synergistic Combination of Oncolytic Virotherapy and Immunotherapy for Glioma By clincancerres.aacrjournals.org Published On :: 2020-05-01T00:05:36-07:00 Purpose: We hypothesized that the combination of a local stimulus for activating tumor-specific T cells and an anti-immunosuppressant would improve treatment of gliomas. Virally encoded IL15Rα-IL15 as the T-cell activating stimulus and a prostaglandin synthesis inhibitor as the anti-immunosuppressant were combined with adoptive transfer of tumor-specific T cells. Experimental Design: Two oncolytic poxviruses, vvDD vaccinia virus and myxoma virus, were each engineered to express the fusion protein IL15Rα-IL15 and a fluorescent protein. Viral gene expression (YFP or tdTomato Red) was confirmed in the murine glioma GL261 in vitro and in vivo. GL261 tumors in immunocompetent C57BL/6J mice were treated with vvDD-IL15Rα-YFP vaccinia virus or vMyx-IL15Rα-tdTr combined with other treatments, including vaccination with GARC-1 peptide (a neoantigen for GL261), rapamycin, celecoxib, and adoptive T-cell therapy. Results: vvDD-IL15Rα-YFP and vMyx-IL15Rα-tdTr each infected and killed GL261 cells in vitro. In vivo, NK cells and CD8+ T cells were increased in the tumor due to the expression of IL15Rα-IL15. Each component of a combination treatment contributed to prolonging survival: an oncolytic virus, the IL15Rα-IL15 expressed by the virus, a source of T cells (whether by prevaccination or adoptive transfer), and prostaglandin inhibition all synergized to produce elimination of gliomas in a majority of mice. vvDD-IL15Rα-YFP occasionally caused ventriculitis-meningitis, but vMyx-IL15Rα-tdTr was safe and effective, causing a strong infiltration of tumor-specific T cells and eliminating gliomas in 83% of treated mice. Conclusions: IL15Rα-IL15–armed oncolytic poxviruses provide potent antitumor effects against brain tumors when combined with adoptive T-cell therapy, rapamycin, and celecoxib. Full Article
vi Preclinical Activity of JNJ-7957, a Novel BCMAxCD3 Bispecific Antibody for the Treatment of Multiple Myeloma, Is Potentiated by Daratumumab By clincancerres.aacrjournals.org Published On :: 2020-05-01T00:05:36-07:00 Purpose: Multiple myeloma (MM) patients with disease refractory to all available drugs have a poor outcome, indicating the need for new agents with novel mechanisms of action. Experimental Design: We evaluated the anti-MM activity of the fully human BCMAxCD3 bispecific antibody JNJ-7957 in cell lines and bone marrow (BM) samples. The impact of several tumor- and host-related factors on sensitivity to JNJ-7957 therapy was also evaluated. Results: We show that JNJ-7957 has potent activity against 4 MM cell lines, against tumor cells in 48 of 49 BM samples obtained from MM patients, and in 5 of 6 BM samples obtained from primary plasma cell leukemia patients. JNJ-7957 activity was significantly enhanced in patients with prior daratumumab treatment, which was partially due to enhanced killing capacity of daratumumab-exposed effector cells. BCMA expression did not affect activity of JNJ-7957. High T-cell frequencies and high effector:target ratios were associated with improved JNJ-7957–mediated lysis of MM cells. The PD-1/PD-L1 axis had a modest negative impact on JNJ-7957 activity against tumor cells from daratumumab-naïve MM patients. Soluble BCMA impaired the ability of JNJ-7957 to kill MM cells, although higher concentrations were able to overcome this negative effect. Conclusions: JNJ-7957 effectively kills MM cells ex vivo, including those from heavily pretreated MM patients, whereby several components of the immunosuppressive BM microenvironment had only modest effects on its killing capacity. Our findings support the ongoing trial with JNJ-7957 as single agent and provide the preclinical rationale for evaluating JNJ-7957 in combination with daratumumab in MM. Full Article
vi Plasma Thymidine Kinase Activity as a Biomarker in Patients with Luminal Metastatic Breast Cancer Treated with Palbociclib within the TREnd Trial By clincancerres.aacrjournals.org Published On :: 2020-05-01T00:05:36-07:00 Purpose: Thymidine kinase 1 (TK1) is downstream to the CDK4/6 pathway, and TK activity (TKa) measured in blood is a dynamic marker of outcome in patients with advanced breast cancer (ABC). This study explores TK1 as a biomarker of palbociclib response, both in vitro and in patients with ABC. Experimental Design: Modulation of TK1 levels and activity by palbociclib were studied in seven estrogen receptor–positive breast cancer cell lines: sensitive (PDS) and with palbociclib acquired resistance (PDR). TKa was assayed in plasma obtained at baseline (T0), after one cycle (T1), and at disease progression on palbociclib (T2) in patients enrolled in the "To Reverse ENDocrine Resistance" (TREnd) trial (n = 46). Results: Among E2F-dependent genes, TK1 was significantly downregulated after short-term palbociclib. Early TKa reduction by palbociclib occurred in PDS but not in PDR cells. In patients, median TKa (mTKa) at T0 was 75 DiviTum units per liter (Du/L), with baseline TKa not proving prognostic. At T1, mTKa decreased to 35 Du/L, with a minority of patients (n = 8) showing an increase—correlating with a worse outcome than those with decreased/stable TKa (n = 33; mPFS 3.0 vs 9.0 months; P = 0.002). At T2, mTKa was 251 Du/L; patients with TKa above the median had worse outcomes on post-study treatment compared with those with lower TKa (2.9 vs 8.7 months; P = 0.05). Conclusions: TK is a dynamic marker of resistance to palbociclib which may lead to early identification of patients in whom treatment escalation may be feasible. In addition, TKa may stratify prognosis in patients with acquired resistance to palbociclib. Full Article
vi Efficacy and Safety of Pembrolizumab in Previously Treated Advanced Neuroendocrine Tumors: Results From the Phase II KEYNOTE-158 Study By clincancerres.aacrjournals.org Published On :: 2020-05-01T00:05:36-07:00 Purpose: KEYNOTE-158 (ClinicalTrials.gov identifier: NCT02628067) investigated the efficacy and safety of pembrolizumab across multiple cancers. We present results from patients with previously treated advanced well-differentiated neuroendocrine tumors (NET). Patients and Methods: Pembrolizumab 200 mg was administered every 3 weeks for 2 years or until progression, intolerable toxicity, or physician/patient decision. Tumor imaging was performed every 9 weeks for the first year and then every 12 weeks. Endpoints included objective response rate (ORR) per RECIST v1.1 by independent central radiologic review (primary) and duration of response (DOR), progression-free survival (PFS), overall survival (OS), and safety (secondary). Results: A total of 107 patients with NETs of the lung, appendix, small intestine, colon, rectum, or pancreas were treated. Median age was 59.0 years (range, 29–80), 44.9% had ECOG performance status 1, 40.2% had received ≥3 prior therapies for advanced disease, and 15.9% had PD-L1–positive tumors (combined positive score ≥1). Median follow-up was 24.2 months (range, 0.6–33.4). ORR was 3.7% (95% CI, 1.0–9.3), with zero complete responses and four partial responses (three pancreatic and one rectal) all in patients with PD-L1–negative tumors. Median DOR was not reached, with one of four responses ongoing after ≥21 months follow-up. Median PFS was 4.1 months (95% CI, 3.5–5.4); the 6-month PFS rate was 39.3%. Median OS was 24.2 months (95% CI, 15.8–32.5). Treatment-related adverse events (AE) occurred in 75.7% of patients, 21.5% of whom had grade 3–5 AEs. Conclusions: Pembrolizumab monotherapy showed limited antitumor activity and manageable safety in patients with previously treated advanced well-differentiated NETs. Full Article
vi Systematic Review of Whole-Genome Sequencing Data To Predict Phenotypic Drug Resistance and Susceptibility in Swedish Mycobacterium tuberculosis Isolates, 2016 to 2018 [Mechanisms of Resistance] By aac.asm.org Published On :: 2020-04-21T08:01:10-07:00 In this retrospective study, whole-genome sequencing (WGS) data generated on an Ion Torrent platform was used to predict phenotypic drug resistance profiles for first- and second-line drugs among Swedish clinical Mycobacterium tuberculosis isolates from 2016 to 2018. The accuracy was ~99% for all first-line drugs and 100% for four second-line drugs. Our analysis supports the introduction of WGS into routine diagnostics, which might, at least in Sweden, replace phenotypic drug susceptibility testing in the future. Full Article
vi Novel Endochin-Like Quinolones Exhibit Potent In Vitro Activity against Plasmodium knowlesi but Do Not Synergize with Proguanil [Susceptibility] By aac.asm.org Published On :: 2020-04-21T08:01:10-07:00 Quinolones, such as the antimalarial atovaquone, are inhibitors of the malarial mitochondrial cytochrome bc1 complex, a target critical to the survival of both liver- and blood-stage parasites, making these drugs useful as both prophylaxis and treatment. Recently, several derivatives of endochin have been optimized to produce novel quinolones that are active in vitro and in animal models. While these quinolones exhibit potent ex vivo activity against Plasmodium falciparum and Plasmodium vivax, their activity against the zoonotic agent Plasmodium knowlesi is unknown. We screened several of these novel endochin-like quinolones (ELQs) for their activity against P. knowlesi in vitro and compared this with their activity against P. falciparum tested under identical conditions. We demonstrated that ELQs are potent against P. knowlesi (50% effective concentration, <117 nM) and equally effective against P. falciparum. We then screened selected quinolones and partner drugs using a longer exposure (2.5 life cycles) and found that proguanil is 10-fold less potent against P. knowlesi than P. falciparum, while the quinolones demonstrate similar potency. Finally, we used isobologram analysis to compare combinations of the ELQs with either proguanil or atovaquone. We show that all quinolone combinations with proguanil are synergistic against P. falciparum. However, against P. knowlesi, no evidence of synergy between proguanil and the quinolones was found. Importantly, the combination of the novel quinolone ELQ-300 with atovaquone was synergistic against both species. Our data identify potentially important species differences in proguanil susceptibility and in the interaction of proguanil with quinolones and support the ongoing development of novel quinolones as potent antimalarials that target multiple species. Full Article
vi Co-occurrence of Plasmid-Mediated Tigecycline and Carbapenem Resistance in Acinetobacter spp. from Waterfowls and Their Neighboring Environment [Epidemiology and Surveillance] By aac.asm.org Published On :: 2020-04-21T08:01:10-07:00 Tigecycline serves as one of the antibiotics of last resort to treat multidrug-resistant (including carbapenem-resistant) pathogens. However, the recently emerged plasmid-mediated tigecycline resistance mechanism, Tet(X), challenges the clinical efficacy of this class of antibiotics. In this study, we detected 180 tet(X)-harboring Acinetobacter isolates (8.9%, n = 180) from 2,018 samples collected from avian farms and adjacent environments in China. Eighteen tet(X)-harboring isolates (10.0%) were found to cocarry the carbapenemase gene blaNDM-1, mostly from waterfowl samples (94.4%, 17/18). Interestingly, among six Acinetobacter strains, tet(X) and blaNDM-1 were found to colocalize on the same plasmids. Moreover, whole-genome sequencing (WGS) revealed a novel orthologue of tet(X) in the six isolates coharboring tet(X) and blaNDM-1. Inverse PCR suggested that the two tet(X) genes form a single transposable unit and may be cotransferred. Sequence comparison between six tet(X)- and blaNDM-1-coharboring plasmids showed that they shared a highly homologous plasmid backbone even though they were isolated from different Acinetobacter species (three from Acinetobacter indicus, two from Acinetobacter schindleri, and one from Acinetobacter lwoffii) from various sources and from different geological regions, suggesting the horizontal genetic transfer of a common tet(X)- and blaNDM-1-coharboring plasmid among Acinetobacter species in China. Emergence and spread of such plasmids and strains are of great clinical concern, and measures must be implemented to avoid their dissemination. Full Article
vi Surveillance of Omadacycline Activity Tested against Clinical Isolates from the United States and Europe: Report from the SENTRY Antimicrobial Surveillance Program, 2016 to 2018 [Epidemiology and Surveillance] By aac.asm.org Published On :: 2020-04-21T08:01:10-07:00 Omadacycline is a broad-spectrum aminomethylcycline approved in October 2018 by the U.S. Food and Drug Administration for treating acute bacterial skin and skin structure infections and community-acquired pneumonia as both an oral and intravenous once-daily formulation. In this report, the activities of omadacycline and comparators were tested against 49,000 nonduplicate bacterial isolates collected prospectively during 2016 to 2018 from medical centers in Europe (24,500 isolates, 40 medical centers [19 countries]) and the United States (24,500 isolates, 33 medical centers [23 states and all 9 U.S. census divisions]). Omadacycline was tested by broth microdilution following the methods in Clinical and Laboratory Standards Institute document M07 (Methods for Dilution Antimicrobial Susceptibility Tests for Bacteria That Grow Aerobically; Approved Standard, 11th ed., 2018). Omadacycline (MIC50/90, 0.12/0.25 mg/liter) inhibited 98.6% of Staphylococcus aureus isolates at ≤0.5 mg/liter, including 96.3% of methicillin-resistant S. aureus isolates and 99.8% of methicillin-susceptible S. aureus isolates. Omadacycline potency was comparable for Streptococcus pneumoniae (MIC50/90, 0.06/0.12 mg/liter), viridans group streptococci (MIC50/90, 0.06/0.12 mg/liter), and beta-hemolytic streptococci (MIC50/90, 0.12/0.25 mg/liter), regardless of species and susceptibility to penicillin, macrolides, or tetracycline. Omadacycline was active against all Enterobacterales tested (MIC50/90, 1/8 mg/liter; 87.5% of isolates were inhibited at ≤4 mg/liter) except Proteus mirabilis (MIC50/90, 16/>32 mg/liter) and indole-positive Proteus spp. (MIC50/90, 8/32 mg/liter) and was most active against Escherichia coli (MIC50/90, 0.5/2 mg/liter), Klebsiella oxytoca (MIC50/90, 1/2 mg/liter), and Citrobacter spp. (MIC50/90, 1/4 mg/liter). Omadacycline inhibited 92.4% of Enterobacter cloacae species complex and 88.5% of Klebsiella pneumoniae isolates at ≤4 mg/liter. Omadacycline was active against Haemophilus influenzae (MIC50/90, 0.5/1 mg/liter), regardless of β-lactamase status, and against Moraxella catarrhalis (MIC50/90, ≤0.12/0.25 mg/liter). The potent activity of omadacycline against Gram-positive and -negative bacteria indicates that omadacycline merits further study in serious infections in which multidrug resistance and mixed Gram-positive and Gram-negative bacterial infections may be a concern. Full Article
vi Antiviral Properties and Mechanism of Action Studies of the Hepatitis B Virus Capsid Assembly Modulator JNJ-56136379 [Antiviral Agents] By aac.asm.org Published On :: 2020-04-21T08:01:10-07:00 Capsid assembly is a critical step in the hepatitis B virus (HBV) life cycle, mediated by the core protein. Core is a potential target for new antiviral therapies, the capsid assembly modulators (CAMs). JNJ-56136379 (JNJ-6379) is a novel and potent CAM currently in phase II trials. We evaluated the mechanisms of action (MOAs) and antiviral properties of JNJ-6379 in vitro. Size exclusion chromatography and electron microscopy studies demonstrated that JNJ-6379 induced the formation of morphologically intact viral capsids devoid of genomic material (primary MOA). JNJ-6379 accelerated the rate and extent of HBV capsid assembly in vitro. JNJ-6379 specifically and potently inhibited HBV replication; its median 50% effective concentration (EC50) was 54 nM (HepG2.117 cells). In HBV-infected primary human hepatocytes (PHHs), JNJ-6379, when added with the viral inoculum, dose-dependently reduced extracellular HBV DNA levels (median EC50 of 93 nM) and prevented covalently closed circular DNA (cccDNA) formation, leading to a dose-dependent reduction of intracellular HBV RNA levels (median EC50 of 876 nM) and reduced antigen levels (secondary MOA). Adding JNJ-6379 to PHHs 4 or 5 days postinfection reduced extracellular HBV DNA and did not prevent cccDNA formation. Time-of-addition PHH studies revealed that JNJ-6379 most likely interfered with postentry processes. Collectively, these data demonstrate that JNJ-6379 has dual MOAs in the early and late steps of the HBV life cycle, which is different from the MOA of nucleos(t)ide analogues. JNJ-6379 is in development for chronic hepatitis B treatment and may translate into higher HBV functional cure rates. Full Article
vi Activity of Plazomicin Tested against Enterobacterales Isolates Collected from U.S. Hospitals in 2016-2017: Effect of Different Breakpoint Criteria on Susceptibility Rates among Aminoglycosides [Susceptibility] By aac.asm.org Published On :: 2020-04-21T08:01:10-07:00 Plazomicin was active against 97.0% of 8,783 Enterobacterales isolates collected in the United States (2016 and 2017), and only 6 isolates carried 16S rRNA methyltransferases conferring resistance to virtually all aminoglycosides. Plazomicin (89.2% to 95.9% susceptible) displayed greater activity than amikacin (72.5% to 78.6%), gentamicin (30.4% to 45.9%), and tobramycin (7.8% to 22.4%) against carbapenem-resistant and extensively drug-resistant isolates. The discrepancies among the susceptibility rates for these agents was greater when applying breakpoints generated using the same stringent contemporary methods applied to determine plazomicin breakpoints. Full Article
vi Activity of Imipenem-Relebactam against Carbapenem-Resistant Escherichia coli Isolates from the United States in Relation to Clonal Background, Resistance Genes, Coresistance, and Region [Epidemiology and Surveillance] By aac.asm.org Published On :: 2020-04-21T08:01:10-07:00 Imipenem-relebactam (I-R) is a recently developed carbapenem–beta-lactamase inhibitor combination agent that can overcome carbapenem resistance, which has now emerged in Escherichia coli, including sequence type 131 (ST131) and its fluoroquinolone-resistant H30R subclone, the leading cause of extraintestinal E. coli infections globally. To clarify the likely utility of I-R for carbapenem-resistant (CR) E. coli infections in the United States, we characterized 203 recent CR clinical E. coli isolates from across the United States (years 2002 to 2017) for phylogroup, clonal group (including ST131, H30R, and the CTX-M-15-associated H30Rx subset within H30R), relevant beta-lactamase genes, and broth microdilution MICs for I-R and 11 comparator agents. Overall, I-R was highly active (89% susceptible), more so than all comparators except tigecycline and colistin (both 99% susceptible). I-R’s activity varied significantly in relation to phylogroup, clonal background, resistance genotype, and region. It was greatest among phylogroup B2, ST131-H30R, H30Rx, Klebsiella pneumoniae carbapenemase (KPC)-positive, and northeast U.S. isolates and lowest among phylogroup C, New Delhi metallo-β-lactamase (NDM)-positive, and southeast U.S. isolates. Relebactam improved imipenem’s activity against CR isolates within each phylogroup—especially groups A, B1, and B2—and particularly against isolates containing KPC. I-R remained substantially active against isolates coresistant to comparator agents, albeit somewhat less so than against the corresponding susceptible isolates. These findings suggest that I-R should be useful for treating most CR E. coli infections in the United States, largely independent of coresistance, although this likely will vary in relation to the local prevalence of specific E. coli lineages and carbapenem resistance mechanisms. Full Article
vi An Individual Participant Data Population Pharmacokinetic Meta-analysis of Drug-Drug Interactions between Lumefantrine and Commonly Used Antiretroviral Treatment [Clinical Therapeutics] By aac.asm.org Published On :: 2020-04-21T08:01:10-07:00 Treating malaria in HIV-coinfected individuals should consider potential drug-drug interactions. Artemether-lumefantrine is the most widely recommended treatment for uncomplicated malaria globally. Lumefantrine is metabolized by CYP3A4, an enzyme that commonly used antiretrovirals often induce or inhibit. A population pharmacokinetic meta-analysis was conducted using individual participant data from 10 studies with 6,100 lumefantrine concentrations from 793 nonpregnant adult participants (41% HIV-malaria-coinfected, 36% malaria-infected, 20% HIV-infected, and 3% healthy volunteers). Lumefantrine exposure increased 3.4-fold with coadministration of lopinavir-ritonavir-based antiretroviral therapy (ART), while it decreased by 47% with efavirenz-based ART and by 59% in the patients with rifampin-based antituberculosis treatment. Nevirapine- or dolutegravir-based ART and malaria or HIV infection were not associated with significant effects. Monte Carlo simulations showed that those on concomitant efavirenz or rifampin have 49% and 80% probability of day 7 concentrations <200 ng/ml, respectively, a threshold associated with an increased risk of treatment failure. The risk of achieving subtherapeutic concentrations increases with larger body weight. An extended 5-day and 6-day artemether-lumefantrine regimen is predicted to overcome these drug-drug interactions with efavirenz and rifampin, respectively. Full Article
vi Investigating the Effects of Osmolytes and Environmental pH on Bacterial Persisters [Susceptibility] By aac.asm.org Published On :: 2020-04-21T08:01:10-07:00 Bacterial persisters are phenotypic variants that temporarily demonstrate an extraordinary tolerance toward antibiotics. Persisters have been linked to the recalcitrance of biofilm-related infections; hence, a complete understanding of their physiology can lead to improvement of therapeutic strategies for such infections. Mechanisms pertaining to persister formation are thought to be associated with stress response pathways triggered by intra- or extracellular stress factors. Unfortunately, studies demonstrating the effects of osmolyte- and/or pH-induced stresses on bacterial persistence are largely missing. To fill this knowledge gap within the field, we studied the effects of various osmolytes and pH conditions on Escherichia coli persistence with the use of phenotype microarrays and antibiotic tolerance assays. Although we found that a number of chemicals and pH environments, including urea, sodium nitrite, and acidic pH, significantly reduced persister formation in E. coli compared to no-osmolyte/no-buffer controls, this reduction in persister levels was less pronounced in late-stationary-phase cultures. Our results further demonstrated a positive correlation between cell growth and persister formation, which challenges the general notion in the field that slow-growing cultures have more persister cells than fast-growing cultures. Full Article
vi In Vitro Activity of KBP-7072, a Novel Third-Generation Tetracycline, against 531 Recent Geographically Diverse and Molecularly Characterized Acinetobacter baumannii Species Complex Isolates [Susceptibility] By aac.asm.org Published On :: 2020-04-21T08:01:10-07:00 KBP-7072 is a novel third-generation tetracycline (aminomethylcycline) antibacterial that overcomes common efflux and ribosomal protection resistance mechanisms that cause resistance in older-generation tetracyclines. KBP-7072 completed phase 1 clinical development studies for safety, tolerability, and pharmacokinetics (ClinicalTrials.gov identifier NCT02454361) and multiple ascending doses in healthy subjects (ClinicalTrials.gov identifier NCT02654626) in December 2015. Both oral and intravenous formulations of KBP-7072 are being developed. In this study, we evaluated the in vitro activities of KBP-7072 and comparator agents by CLSI document M07 (2018) broth microdilution against 531 recent geographically diverse and/or molecularly characterized Acinetobacter baumannii-A. calcoaceticus species complex (A. baumannii) isolates from the United States, Europe, Asia-Pacific (excluding China), and Latin America. A. baumannii isolates included carbapenem-resistant, colistin-resistant, tetracycline-resistant, and extended-spectrum-β-lactamase (ESBL)- and metallo-β-lactamase (MBL)-producing isolates. Overall, KBP-7072 (MIC50/90, 0.25/1 mg/liter) was comparable in activity to colistin (92.8%/92.8% susceptible [S] [CLSI/EUCAST]) against A. baumannii isolates, inhibiting 99.2% of isolates at ≤2 mg/liter and 97.6% of isolates at ≤1 mg/liter. KBP-7072 was equally active against A. baumannii isolates, including carbapenem-resistant, colistin-resistant, and tetracycline-resistant isolates, regardless of geographic location, and maintained activity against ESBL- and MBL-producing isolates. KBP-7072 outperformed comparator agents, including ceftazidime (40.3% S [CLSI]), gentamicin (48.2%/48.2% S [CLSI/EUCAST]), levofloxacin (39.5%/37.9% S [CLSI/EUCAST]), meropenem (42.0%/42.0% S [CLSI/EUCAST]), piperacillin-tazobactam (33.3% S [CLSI]), and all tetracycline-class comparator agents, which include doxycycline (67.3% S [CLSI]), minocycline (73.8% S [CLSI]), tetracycline (37.2% S [CLSI]), and tigecycline (79.5% inhibited by ≤2 mg/liter). The potent in vitro activity of KBP-7072 against recent geographically diverse, molecularly characterized, and drug-resistant A. baumannii isolates supports continued clinical development for the treatment of serious infections, including those caused by A. baumannii. Full Article
vi In Vitro Activity of Ceftazidime-Avibactam against Isolates from Respiratory and Blood Specimens from Patients with Nosocomial Pneumonia, Including Ventilator-Associated Pneumonia, in a Phase 3 Clinical Trial [Susceptibility] By aac.asm.org Published On :: 2020-04-21T08:01:10-07:00 Nosocomial pneumonia (NP), including ventilator-associated pneumonia (VAP), is increasingly associated with multidrug-resistant Gram-negative pathogens. This study describes the in vitro activity of ceftazidime-avibactam, ceftazidime, and relevant comparator agents against bacterial pathogens isolated from patients with NP, including VAP, enrolled in a ceftazidime-avibactam phase 3 trial. Gram-positive pathogens were included if coisolated with a Gram-negative pathogen. In vitro susceptibility was determined at a central laboratory using Clinical and Laboratory Standards Institute broth microdilution methods. Of 817 randomized patients, 457 (55.9%) had ≥1 Gram-negative bacterial pathogen(s) isolated at baseline, and 149 (18.2%) had ≥1 Gram-positive pathogen(s) coisolated. The most common isolated pathogens were Klebsiella pneumoniae (18.8%), Pseudomonas aeruginosa (15.8%), and Staphylococcus aureus (11.5%). Ceftazidime-avibactam was highly active in vitro against 370 isolates of Enterobacteriaceae, with 98.6% susceptible (MIC90, 0.5 μg/ml) compared with 73.2% susceptible for ceftazidime (MIC90, >64 μg/ml). The percent susceptibility values for ceftazidime-avibactam and ceftazidime against 129 P. aeruginosa isolates were 88.4% and 72.9% (MIC90 values of 16 μg/ml and 64 μg/ml), respectively. Among ceftazidime-nonsusceptible Gram-negative isolates, ceftazidime-avibactam percent susceptibility values were 94.9% for 99 Enterobacteriaceae and 60.0% for 35 P. aeruginosa. MIC90 values for linezolid and vancomycin (permitted per protocol for Gram-positive coverage) were within their respective MIC susceptibility breakpoints against the Gram-positive pathogens isolated. This analysis demonstrates that ceftazidime-avibactam was active in vitro against the majority of Enterobacteriaceae and P. aeruginosa isolates from patients with NP, including VAP, in a phase 3 trial. (This study has been registered at ClinicalTrials.gov under identifier NCT01808092.) Full Article
vi Synergistic Activity of Clofazimine and Clarithromycin in an Aerosol Mouse Model of Mycobacterium avium Infection [Experimental Therapeutics] By aac.asm.org Published On :: 2020-04-21T08:01:10-07:00 Infections with nontuberculous mycobacteria (NTM) have a poor prognosis in patients with underlying respiratory diseases. Clofazimine (CFZ) showed both experimental and clinical promising results against clinically relevant NTM. However, there are no data on CFZ in combination with the current recommended treatment; therefore, we aimed to study its in vivo activity in an aerosol mouse model of Mycobacterium avium. In an aerosol infection BALB/c mouse model using M. avium strain Chester, we treated 58 mice with four combinations of rifampin (RIF) at 10 mg/kg, CFZ at 25 mg/kg, and clarithromycin (CLR) and ethambutol (EMB) at 100 mg/kg. Treatment efficacy was assessed on the basis of lung CFU counts after 2 (M2) and 4 (M4) months of treatment. At M2, CLR-RIF-EMB was slightly but significantly more efficient than CFZ-RIF-EMB (3.02 ± 0.12 versus 3.55 ± 0.28, respectively, P < 0.01), whereas CLR-CFZ-EMB and CLR-CFZ-RIF-EMB dramatically decreased lung CFU counts by 4.32 and 4.47 log10, respectively, compared to untreated group. At M4, CLR-RIF-EMB was significantly more efficient than CFZ-RIF-EMB (2 ± 0.53 versus 2.66 ± 0.22, respectively, P = 0.01). The addition of CLZ to CLR dramatically decreased the lung CFU count, with CFU counts 5.41 and 5.79 log10 lower in the CLR-CFZ-EMB and CLR-CFZ-RIF-EMB groups, respectively, than in the untreated group. The addition of CFZ to CLR seems to improve the efficacy of CLR as early as M2 and was confirmed at M4. CFZ, in addition to RIF and EMB, on the other hand, is less effective than CLR-RIF-EMB. These results need to be confirmed by similar studies along with CFZ potential for shortening treatment. Full Article
vi Thiostrepton Reactivates Latent HIV-1 through the p-TEFb and NF-{kappa}B Pathways Mediated by Heat Shock Response [Antiviral Agents] By aac.asm.org Published On :: 2020-04-21T08:01:10-07:00 Antiretroviral therapy (ART) suppresses HIV-1 replication but fails to cure the infection. The presence of an extremely stable viral latent reservoir, primarily in resting memory CD4+ T cells, remains a major obstacle to viral eradication. The "shock and kill" strategy targets these latently infected cells and boosts immune recognition and clearance, and thus, it is a promising approach for an HIV-1 functional cure. Although some latency-reversing agents (LRAs) have been reported, no apparent clinical progress has been made, so it is still vital to seek novel and effective LRAs. Here, we report that thiostrepton (TSR), a proteasome inhibitor, reactivates latent HIV-1 effectively in cellular models and in primary CD4+ T cells from ART-suppressed individuals ex vivo. TSR does not induce global T cell activation, severe cytotoxicity, or CD8+ T cell dysfunction, making it a prospective LRA candidate. We also observed a significant synergistic effect of reactivation when TSR was combined with JQ1, prostratin, or bryostatin-1. Interestingly, six TSR analogues also show reactivation abilities that are similar to or more effective than that of TSR. We further verified that TSR upregulated expression of heat shock proteins (HSPs) in CD4+ T cells, which subsequently activated positive transcriptional elongation factor b (p-TEFb) and NF-B signals, leading to viral reactivation. In summary, we identify TSR as a novel LRA which could have important significance for applications to an HIV-1 functional cure in the future. Full Article
vi Meropenem-Vaborbactam versus Ceftazidime-Avibactam for Treatment of Carbapenem-Resistant Enterobacteriaceae Infections [Clinical Therapeutics] By aac.asm.org Published On :: 2020-04-21T08:01:10-07:00 The comparative efficacy of ceftazidime-avibactam and meropenem-vaborbactam for treatment of carbapenem-resistant Enterobacteriaceae (CRE) infections remains unknown. This was a multicenter, retrospective cohort study of adults with CRE infections who received ceftazidime-avibactam or meropenem-vaborbactam for ≥72 hours from February 2015 to October 2018. Patients with a localized urinary tract infection and repeat study drug exposures after the first episode were excluded. The primary endpoint was clinical success compared between treatment groups. Secondary endpoints included 30- and 90-day mortality, adverse events (AE), 90-day CRE infection recurrence, and development of resistance in patients with recurrent infection. A post hoc subgroup analysis was completed comparing patients who received ceftazidime-avibactam monotherapy, ceftazidime-avibactam combination therapy, and meropenem-vaborbactam monotherapy. A total of 131 patients were included (ceftazidime-avibactam, n = 105; meropenem-vaborbactam, n = 26), 40% of whom had bacteremia. No significant difference in clinical success was observed between groups (62% versus 69%; P = 0.49). Patients in the ceftazidime-avibactam arm received combination therapy more often than patients in the meropenem-vaborbactam arm (61% versus 15%; P < 0.01). No difference in 30- and 90-day mortality resulted, and rates of AE were similar between groups. In patients with recurrent infection, development of resistance occurred in three patients that received ceftazidime-avibactam monotherapy and in no patients in the meropenem-vaborbactam arm. Clinical success was similar between patients receiving ceftazidime-avibactam and meropenem-vaborbactam for treatment of CRE infections, despite ceftazidime-avibactam being used more often as a combination therapy. Development of resistance was more common with ceftazidime-avibactam monotherapy. Full Article
vi Evaluation of Dose-Fractionated Polymyxin B on Acute Kidney Injury Using a Translational In Vivo Rat Model [Pharmacology] By aac.asm.org Published On :: 2020-04-21T08:01:10-07:00 We investigated dose-fractionated polymyxin B (PB) on acute kidney injury (AKI). PB at 12 mg of drug/kg of body weight per day (once, twice, and thrice daily) was administered in rats over 72 h. The thrice-daily group demonstrated the highest KIM-1 increase (P = 0.018) versus that of the controls (P = 0.99) and histopathological damage (P = 0.013). A three-compartment model best described the data (bias, 0.129 mg/liter; imprecision, 0.729 mg2/liter2; R2, 0.652,). Area under the concentration-time curve at 24 h (AUC24) values were similar (P = 0.87). The thrice-daily dosing scheme resulted in the most PB-associated AKI in a rat model. Full Article
vi A Novel Inhaled Dry-Powder Formulation of Ribavirin Allows for Efficient Lung Delivery in Healthy Participants and Those with Chronic Obstructive Pulmonary Disease in a Phase 1 Study [Antiviral Agents] By aac.asm.org Published On :: 2020-04-21T08:01:10-07:00 Chronic obstructive pulmonary disease (COPD) is an inflammatory lung condition, causing progressive decline in lung function leading to premature death. Acute exacerbations in COPD patients are predominantly associated with respiratory viruses. Ribavirin is a generic broad-spectrum antiviral agent that could be used for treatment of viral respiratory infections in COPD. Using the Particle Replication In Nonwetting Templates (PRINT) technology, which produces dry-powder particles of uniform shape and size, two new inhaled formulations of ribavirin (ribavirin-PRINT-CFI and ribavirin-PRINT-IP) were developed for efficient delivery to the lung and to minimize bystander exposure. Ribavirin-PRINT-CFI was well tolerated in healthy participants after single dosing and ribavirin-PRINT-IP was well tolerated in healthy and COPD participants after single and repeat dosing. Ribavirin-PRINT-CFI was replaced with ribavirin-PRINT-IP since the latter formulation was found to have improved physicochemical properties and it had a higher ratio of active drug to excipient per unit dose. Ribavirin concentrations were measured in lung epithelial lining fluid in both healthy and COPD participants and achieved target concentrations. Both formulations were rapidly absorbed with approximately dose proportional pharmacokinetics in plasma. Exposure to bystanders was negligible based on both the plasma and airborne ribavirin concentrations with the ribavirin-PRINT-IP formulation. Thus, ribavirin-PRINT-IP allowed for an efficient and convenient delivery of ribavirin to the lungs while minimizing systemic exposure. Further clinical investigations would be required to demonstrate ribavirin-PRINT-IP antiviral characteristics and impact on COPD viral-induced exacerbations. (The clinical trials discussed in this study have been registered at ClinicalTrials.gov under identifiers NCT03243760 and NCT03235726.) Full Article
vi In Vitro Screening of the Open-Source Medicines for Malaria Venture Malaria and Pathogen Boxes To Discover Novel Compounds with Activity against Balamuthia mandrillaris [Susceptibility] By aac.asm.org Published On :: 2020-04-21T08:01:10-07:00 Balamuthia mandrillaris is an under-reported, pathogenic free-living amoeba that causes Balamuthia amoebic encephalitis (BAE) and cutaneous skin infections. Although cutaneous infections are not typically lethal, BAE with or without cutaneous involvement is usually fatal. This is due to the lack of drugs that are both efficacious and can cross the blood-brain barrier. We aimed to discover new leads for drug discovery by screening the open-source Medicines for Malaria Venture (MMV) Malaria Box and MMV Pathogen Box, with 800 compounds total. From an initial single point screen at 1 and 10 μM, we identified 54 hits that significantly inhibited the growth of B. mandrillaris in vitro. Hits were reconfirmed in quantitative dose-response assays and 23 compounds (42.6%) were confirmed with activity greater than miltefosine, the current standard of care. Full Article
vi Hydrogen Peroxide-Mediated Oxygen Enrichment Eradicates Helicobacter pylori In Vitro and In Vivo [Experimental Therapeutics] By aac.asm.org Published On :: 2020-04-21T08:01:09-07:00 Helicobacter pylori is an important risk factor for gastric ulcers. However, antibacterial therapies increase the resistance rate and decrease the eradication rate of H. pylori. Inspired by the microaerophilic characteristics of H. pylori, we aimed at effectively establishing an oxygen-enriched environment to eradicate and prevent the recurrence of H. pylori. The effect and the mechanism of an oxygen-enriched environment in eradicating H. pylori and preventing the recurrence were explored in vitro and in vivo. During oral administration and after drug withdrawal, H. pylori counts were evaluated by Giemsa staining in animal cohorts. An oxygen-enriched environment in which H. pylori could not survive was successfully established by adding hydrogen peroxide into several solutions and rabbit gastric juice. Hydrogen peroxide effectively killed H. pylori in Columbia blood agar and special peptone broth. Minimum inhibition concentrations and minimum bactericidal concentrations of hydrogen peroxide were both relatively stable after promotion of resistance for 30 generations, indicating that hydrogen peroxide did not easily promote resistance in H. pylori. In models of Mongolian gerbils and Kunming mice, hydrogen peroxide has been shown to significantly eradicate and effectively prevent the recurrence of H. pylori without toxicity and damage to the gastric mucosa. The mechanism of hydrogen peroxide causing H. pylori death was related to the disruption of bacterial cell membranes. The oxygen-enriched environment achieved by hydrogen peroxide eradicates and prevents the recurrence of H. pylori by damaging bacterial cell membranes. Hydrogen peroxide thus provides an attractive candidate for anti-H. pylori treatment. Full Article
vi In Vitro Activity of Beauvericin against All Developmental Stages of Sarcoptes scabiei [Susceptibility] By aac.asm.org Published On :: 2020-04-21T08:01:09-07:00 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. Full Article
vi Discordance between Etravirine Phenotype and Genotype-Based Predicted Phenotype for Subtype C HIV-1 from First-Line Antiretroviral Therapy Failures in South Africa [Antiviral Agents] By aac.asm.org Published On :: 2020-04-21T08:01:09-07:00 Etravirine (ETR) is a nonnucleoside reverse transcriptase inhibitor (NNRTI) used in treatment-experienced individuals. Genotypic resistance test-interpretation systems can predict ETR resistance; however, genotype-based algorithms are derived primarily from HIV-1 subtype B and may not accurately predict resistance in non-B subtypes. The frequency of ETR resistance among recombinant subtype C HIV-1 and the accuracy of genotypic interpretation systems were investigated. HIV-1LAI containing full-length RT from HIV-1 subtype C-positive individuals experiencing virologic failure (>10,000 copies/ml and >1 NNRTI resistance-associated mutation) were phenotyped for ETR susceptibility. Fold change (FC) was calculated against a composite 50% effective concentration (EC50) from treatment-naive individuals and three classifications were assigned: (i) <2.9-FC, susceptible; (ii) ≥2.9- to 10-FC, partially resistant; and (iii) >10-FC, fully resistant. The Stanford HIVdb-v8.4 was used for genotype predictions merging the susceptible/potential low-level and low-level/intermediate groups for 3 x 3 comparison. Fifty-four of a hundred samples had reduced ETR susceptibility (≥2.9-FC). The FC correlated with HIVdb-v8.4 (Spearman’s rho = 0.62; P < 0.0001); however, 44% of samples were partially (1 resistance classification difference) and 4% completely discordant (2 resistance classification differences). Of the 34 samples with an FC of >10, 26 were HIVdb-v8.4 classified as low-intermediate resistant. Mutations L100I, Y181C, or M230L were present in 27/34 (79%) of samples with an FC of >10 but only in 2/46 (4%) of samples with an FC of <2.9. No other mutations were associated with ETR resistance. Viruses containing the mutation K65R were associated with reduced ETR susceptibility, but 65R reversions did not increase ETR susceptibility. Therefore, genotypic interpretation systems were found to misclassify ETR susceptibility in HIV-1 subtype C samples. Modifications to genotypic algorithms are needed to improve the prediction of ETR resistance for the HIV-1 subtype C. Full Article
vi 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] By aac.asm.org Published On :: 2020-04-21T08:01:09-07:00 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. Full Article
vi Antimicrobial Activity of the Quinoline Derivative HT61 against Staphylococcus aureus Biofilms [Susceptibility] By aac.asm.org Published On :: 2020-04-21T08:01:09-07:00 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. Full Article
vi Effects of Tenofovir on the Single-Dose Pharmacokinetics of Intravenous Morinidazole in Healthy Chinese Subjects [Pharmacology] By aac.asm.org Published On :: 2020-04-21T08:01:09-07:00 The effects of multiple-dose administration of tenofovir disoproxil fumarate (TDF) on the pharmacokinetics of morinidazole (MOR) were compared in healthy subjects. MOR exposure was similar, with an area under the curve from 0 h to infinity (AUC0-) treatment ratio for MOR+TDF/MOR of 1.01 (90% confidence interval, 0.97 to 1.06). No relevant differences were observed regarding plasma exposure of metabolites. Renal clearances of MOR and its metabolites were not affected by TDF. No unexpected safety or tolerability issues were observed. Full Article
vi Novel Insights into Plasmodium vivax Therapeutic Failure: CYP2D6 Activity and Time of Exposure to Malaria Modulate the Risk of Recurrence [Epidemiology and Surveillance] By aac.asm.org Published On :: 2020-04-21T08:01:09-07:00 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. Full Article
vi Synthesis and Biological Activity of Novel Zinc-Itraconazole Complexes in Protozoan Parasites and Sporothrix spp. [Susceptibility] By aac.asm.org Published On :: 2020-04-21T08:01:09-07:00 The new complexes Zn(ITZ)2Cl2 (1) and Zn(ITZ)2(OH)2 (2) were synthetized by a reaction of itraconazole with their respective zinc salts under reflux. These Zn-ITZ complexes were characterized by elemental analyses, molar conductivity, mass spectrometry, 1H and 13C{1H} nuclear magnetic resonance, and UV-vis and infrared spectroscopies. The antiparasitic and antifungal activity of Zn-ITZ complexes was evaluated against three protozoans of medical importance, namely, Leishmania amazonensis, Trypanosoma cruzi, and Toxoplasma gondii, and two fungi, namely, Sporothrix brasiliensis and Sporothrix schenckii. The Zn-ITZ complexes exhibited a broad spectrum of action, with antiparasitic and antifungal activity in low concentrations. The strategy of combining zinc with ITZ was efficient to enhance ITZ activity since Zn-ITZ-complexes were more active than the azole alone. This study opens perspectives for future applications of these Zn-ITZ complexes in the treatment of parasitic diseases and sporotrichosis. Full Article
vi In Vitro and Intracellular Activities of Omadacycline against Legionella pneumophila [Susceptibility] By aac.asm.org Published On :: 2020-04-21T08:01:09-07:00 Omadacycline is an aminomethylcycline antibiotic with in vitro activity against pathogens causing community-acquired bacterial pneumonia (CABP). This study investigated the activity of omadacycline against Legionella pneumophila strains isolated between 1995 and 2014 from nosocomial or community-acquired respiratory infections. Omadacycline exhibited extracellular activity similar to comparator antibiotics; intracellular penetrance was found by day 3 of omadacycline exposure. These results support the utility of omadacycline as an effective antibiotic for the treatment of CABP caused by L. pneumophila. Full Article
vi 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
vi 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
vi 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
vi 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
vi 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
vi 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
vi Compounds with Therapeutic Potential against Novel Respiratory 2019 Coronavirus [Minireviews] By aac.asm.org Published On :: 2020-04-21T08:01:09-07:00 Currently, the expansion of the novel human respiratory coronavirus (known as SARS-CoV-2 [severe acute respiratory syndrome coronavirus 2], COVID-2019 [coronavirus disease 2019], or 2019-nCoV [2019 novel coronavirus]) has stressed the need for therapeutic alternatives to alleviate and stop this new epidemic. The previous epidemics of infections by high-morbidity human coronaviruses, such as SARS-CoV in 2003 and the Middle East respiratory syndrome coronavirus (MERS-CoV) in 2012, prompted the characterization of compounds that could be potentially active against the currently emerging novel coronavirus, SARS-CoV-2. The most promising compound is remdesivir (GS-5734), a nucleotide analog prodrug currently in clinical trials for treating Ebola virus infections. Remdesivir inhibited the replication of SARS-CoV and MERS-CoV in tissue cultures, and it displayed efficacy in nonhuman animal models. In addition, a combination of the human immunodeficiency virus type 1 (HIV-1) protease inhibitors lopinavir/ritonavir and interferon beta (LPV/RTV–IFN-β) was shown to be effective in patients infected with SARS-CoV. LPV/RTV–IFN-β also improved clinical parameters in marmosets and mice infected with MERS-CoV. Remarkably, the therapeutic efficacy of remdesivir appeared to be superior to that of LPV/RTV–IFN-β against MERS-CoV in a transgenic humanized mouse model. The relatively high mortality rates associated with these three novel human coronavirus infections, SARS-CoV, MERS-CoV, and SARS-CoV-2, have suggested that proinflammatory responses might play a role in the pathogenesis. It remains unknown whether the generated inflammatory state should be targeted. Therapeutics that target the coronavirus alone might not be able to reverse highly pathogenic infections. This minireview aims to provide a summary of therapeutic compounds that have shown potential in fighting SARS-CoV-2 infections. Full Article
vi 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
vi 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
vi 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
vi 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
vi 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
vi 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
vi Tuning the Antigen Density Requirement for CAR T-cell Activity [Research Articles] By cancerdiscovery.aacrjournals.org Published On :: 2020-05-01T00:05:26-07:00 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 Full Article
vi 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
vi 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