Background:

The number of medical undergraduate and postgraduate students completing palliative care clinical rotations in Canadian medical schools is currently unknown. The aim of this study was to assess the proportion of Canadian medical trainees completing clinical rotations in palliative care and to determine whether changes took place between 2008 and 2018.

Methods:

In this descriptive study, all Canadian medical schools (n = 17) were invited to provide data at the undergraduate and postgraduate levels (2007/08–2015/16 and 2007/08–2017/18, respectively). Information collected included the number, type and length of palliative care clinical rotations offered and the total number of medical trainees or residents enrolled at each school.

Results:

All 17 Canadian medical schools responded to the request for information. At the undergraduate level, palliative care clinical rotations were not offered in 2 schools, mandatory in 2 and optional in 13. Three schools that offered optional rotations were unable to provide complete data and were therefore excluded from further analyses. In 2015/16, only 29.7% of undergraduate medical students completed palliative care clinical rotations, yet this was a significant improvement compared to 2011/12 (13.6%, p = 0.02). At the postgraduate level, on average, 57.9% of family medicine trainees completed such rotations between 2007/08 and 2016/17. During the same period, palliative care clinical rotations were completed by trainees in specialty or subspecialty programs in anesthesiology (34.2%), geriatric medicine (64.4%), internal medicine (30.9%), neurology (28.2%) and psychiatry (64.5%).

Interpretation:

Between 2008 and 2018, a large proportion of Canadian medical trainees graduated without the benefit of a clinical rotation in palliative care. Without dedicated clinical exposure to palliative care, many physicians will enter practice without vital palliative care competencies.

The aim of this study was to assess the association of high-sensitivity cardiac troponin (hs-cTnT) and other cardiac, kidney, hyperglycemia, and inflammatory biomarkers with peripheral neuropathy (PN) in a community-based population.We conducted a cross-sectional analysis of 3056 black and white participants in the Atherosclerosis Risk in Communities (ARIC) study who underwent standardized monofilament PN testing and had measures of cardiac function (hs-cTnT, N-terminal pro–B-type natriuretic peptide [NT-proBNP], and growth differentiation factor 15 [GDF15]), kidney function (serum creatinine, cystatin C, β-2 microglobulin, urine albumin-to-creatinine ratio), hyperglycemia (fasting glucose, hemoglobin A_1c [Hb A_1c], fructosamine, glycated albumin, 1,5-anhydroglucitol), and inflammation (C-reactive protein) assessed at visit 6 (2016–2017; age 71–94 years). We used logistic regression to assess the associations of these biomarkers (modeled in diabetes-specific tertiles) with PN in older adults with and without diabetes after adjusting for traditional risk factors.In total, 33.5% of participants had PN (37.3% with diabetes and 31.9% without diabetes). There was an independent association of hs-cTnT with PN regardless of diabetes status (diabetes T3 vs. T1: odds ratio [OR], 2.15 [95% CI, 1.44–3.22]; no diabetes: OR, 2.31 [95%CI, 1.76–3.03]; P = 0.72 for interaction). Among participants without diabetes, there were also significant associations of NT-proBNP (OR, 1.40 [95% CI, 1.08–1.81]) and urine albumin-to-creatinine ratio (OR, 1.55 [95% CI, 1.22–1.97]) with PN. Associations of hyperglycemia biomarkers including Hb A_1c (OR, 1.76 [95% CI, 1.22–2.54]), fructosamine (OR, 1.71 [95% CI, 1.19–2.46]), and glycated albumin (OR, 1.45 [95% CI, 1.03–2.03]) with PN were significant only among participants with diabetes.Overall, hs-cTnT appears to be a global marker of end organ damage, including PN. Laboratory biomarkers may be able to help us identify those individuals with PN.

S100A8/A9 is implicated in inflammation mechanisms related to atherosclerosis and plaque vulnerability, but it remains unclear whether S100A8/A9 is associated with the prognosis of ischemic stroke. The aim of this study was to investigate these associations in 2 independent multicenter cohorts.Plasma S100A8/A9 concentrations at baseline were measured among 4785 patients with ischemic stroke from 2 independent cohorts: Infectious Factors, Inflammatory Markers, and Prognosis of Acute Ischemic Stroke (IIPAIS) and China Antihypertensive Trial in Acute Ischemic Stroke (CATIS). The primary outcome was a composite outcome of death or major disability at 3 months after ischemic stroke. Secondary outcomes were major disability, death, and a composite outcome of death or vascular events.Among the combined participants of IIPAIS and CATIS, the adjusted odds ratios associated with the highest quartile of plasma S100A8/A9 were 2.11 (95% CI, 1.66–2.68) for the primary outcome and 1.62 (95% CI, 1.27–2.07) for the secondary outcome of major disability; adjusted hazard ratios were 4.14 (95% CI, 2.10–8.15) for the secondary outcome of death and 2.08 (95% CI, 1.38–3.13) for the composite outcome of death or vascular events. Each SD increase of log-transformed S100A8/A9 was associated with 28% (95% CI, 18%–39%; P < 0.001) increased risk of the primary outcome. Multivariable-adjusted spline regression analyses showed a linear association between plasma S100A8/A9 concentrations and primary outcome (P < 0.001 for linearity). Subgroup analyses further confirmed these associations.High plasma S100A8/A9 concentrations at baseline were independently associated with increased risks of adverse clinical outcomes at 3 months after ischemic stroke, suggesting that S100A8/A9 might have a role as a prognostic marker of ischemic stroke.

Cushing syndrome results from chronic excessive exposure to glucocorticoids, impacting virtually every organ system with the most dominant effects on fat metabolism, immune function, and musculoskeletal systems. Endogenous Cushing syndrome is rare, most usually due to excess ACTH secretion from pituitary, and less frequently from ectopic tumors. Other cases result from ACTH-independent adrenal overproduction of cortisol.

This interesting case report from South Africa focuses on a difficult diagnostic challenge: apparent Cushing syndrome with inconsistent laboratory findings.

The measurement of neuron-specific enolase (NSE) in serum is frequently requested for diagnosis, risk stratification, and treatment monitoring of neuroblastoma (NB) in the pediatric population. However, authoritative clinical practice guidelines advise about the poor diagnostic performance of NSE.We critically appraised the available literature evaluating the diagnostic and prognostic value of NSE in the management of NB, paying special attention to the definition of appropriate threshold levels. In addition, we discuss the interfering conditions causing artifactual increases of NSE concentrations in serum and potentially influencing the clinical evaluation of patients with suspected NB.No definitive evidence supports the use of serum NSE for diagnosis and monitoring of NB. The risk of obtaining false-positive NSE results associated with confounders (e.g., sample hemolysis) and other pathophysiologic conditions (e.g., inflammation) is remarkable and hampers the diagnostic value of this test. NSE may be helpful to define the risk of death of patients with NB, mainly in the advanced stages of disease. However, further studies validating currently marketed immunoassays and defining threshold values useful for this scope are warranted.

Cancer continues to be one of the leading causes of morbidity and mortality in the US. Although the treatment of cancer has evolved over the past decades with the use of targeted therapies and immunotherapy, many of these new treatments are expensive and are not readily available to everyone. Moreover, the recent success with treatment advances are not generalized to all cancer types, as some cancers continue to be devastating without significant progress in treatment options. Hence, early detection through population screening remains a critical armament against cancer.

Cushing syndromeExogenousDexamethasoneSkinWhiteningCream

Cardiovascular (CV) disease remains an important cause of morbidity and mortality for patients with chronic kidney disease (CKD). Although clustering of traditional risk factors with CKD is well recognized, kidney-specific mechanisms are believed to drive the disproportionate burden of CV disease. One perturbation that is frequently observed at high rates in patients with CKD is vascular calcification, which may be a central mediator for an array of CV sequelae. This review summarizes the pathophysiological bases of intimal and medial vascular calcification in CKD, current strategies for diagnosis and management, and posits vascular calcification as a risk marker and therapeutic target.

Dramatically rising costs in drug development are in large part because of the high failure rates in clinical phase trials. The poor correlation of animal studies to human toxicity and efficacy have led many developers to question the value of requiring animal studies in determining which drugs should enter in-human trials. Part 1 of this 2-part series examined some of the data regarding the lack of concordance between animal toxicity studies and human trials, as well as some of the potential reasons behind it. This second part of the series focuses on some alternatives to animal trials (hereafter referred to as animal research) as well as current regulatory discussions and developments regarding such alternatives.

Combined pre-and post-capillary hypertension (CpcPH) is a relatively common complication of heart failure (HF) associated with a poor prognosis. Currently, there is no specific therapy approved for this entity. Recently, treatment with beta-3 adrenergic receptor (β3AR) agonists was able to improve pulmonary hemodynamics and right ventricular (RV) performance in a translational, large animal model of chronic PH. The authors present the design of a phase II randomized clinical trial that tests the benefits of mirabegron (a clinically available β3AR agonist) in patients with CpcPH due to HF. The effect of β3AR treatment will be evaluated on pulmonary hemodynamics, as well as clinical, biochemical, and advanced cardiac imaging parameters. (Beta3 Agonist Treatment in Chronic Pulmonary Hypertension Secondary to Heart Failure [SPHERE-HF]; NCT02775539)

We are already a couple of months into 2020 and I hope you had a good start to the new year. I wish you, our readers, reviewers, authors and editors, happiness, success and health in this new decade.

In low-dose computed tomography (LDCT) screening for lung cancer, all three main conditions for overdiagnosis in cancer screening are present: 1) a reservoir of slowly or nongrowing lung cancer exists; 2) LDCT is a high-resolution imaging technology with the potential to identify this reservoir; and 3) eligible screening participants have a high risk of dying from causes other than lung cancer. The degree of overdiagnosis in cancer screening is most validly estimated in high-quality randomised controlled trials (RCTs), with enough follow-up time after the end of screening to avoid lead-time bias and without contamination of the control group.

Nine RCTs investigating LDCT screening were identified. Two RCTs were excluded because lung cancer incidence after the end of screening was not published. Two other RCTs using active comparators were also excluded. Therefore, five RCTs were included: two trials were at low risk of bias, two of some concern and one at high risk of bias. In a meta-analysis of the two low risk of bias RCTs including 8156 healthy current or former smokers, 49% of the screen-detected cancers were overdiagnosed. There is uncertainty about this substantial degree of overdiagnosis due to unexplained heterogeneity and low precision of the summed estimate across the two trials.

Key points

Nine randomised controlled trials (RCTs) on low-dose computed tomography screening were identified; five were included for meta-analysis but only two of those were at low risk of bias.

In a meta-analysis of recent low risk of bias RCTs including 8156 healthy current or former smokers from developed countries, we found that 49% of the screen-detected cancers may be overdiagnosed.

There is uncertainty about the degree of overdiagnosis in lung cancer screening due to unexplained heterogeneity and low precision of the point estimate.

If only high-quality RCTs are included in the meta-analysis, the degree of overdiagnosis is substantial.

Educational aims

To appreciate that low-dose computed tomography screening for lung cancer meets all three main conditions for overdiagnosis in cancer screening: a reservoir of indolent cancers exists in the population; the screening test is able to "tap" this reservoir by detecting biologically indolent cancers as well as biologically important cancers; and the population being screened is characterised by a relatively high competing risk of death from other causes

To learn about biases that might affect the estimates of overdiagnosis in randomised controlled trials in cancer screening

Since lung cancer (LC) is still the leading cause of cancer deaths worldwide [1], early detection through screening represents an important opportunity to improve LC survival and is a priority area for cancer care. The National Lung Screening Trial (NLST) aimed to compare low-dose helical computed tomography (LDCT) with chest radiography in LC screening of current or former heavy smokers. The trial found a relative reduction in mortality from LC of 20% in those who had undergone LDCT screening. LC screening has regained prominence in the thoracic oncology literature with the completion of NELSON and other European trials, which support the role of LC screening in achieving early diagnosis and reducing mortality. A growing number of implementation pilots are providing an impetus towards organised, national programmes for LC screening, which are in need of long-term follow-up data such as those presented in this study.

The diagnostic process of idiopathic interstitial pneumonias (IIPs) is complex and the underlying mechanisms that participate in these diseases still need to be fully understood. In 2015, the European Respiratory Society/American Thoracic Society Task Force on Undifferentiated Forms of Connective Tissue Disease-Associated Interstitial Lung Disease introduced the term "interstitial pneumonia with autoimmune features" (IPAF) to identify subjects with IIP and features suggesting background autoimmunity but not characterisable connective tissue disease (CTD) [1]. The need for a proper clinical, serological and morphological assessment of IIP was highlighted to identify potential subjects with IPAF and CTD-ILD. However, the measurement of anti-neutrophil cytoplasmic antibodies (ANCAs) is not included in the definition of IPAF and ANCA serological testing is only recommended in idiopathic pulmonary fibrosis (IPF) when a clinical suspicion of vasculitis exists [2]. As current research evaluates the prognostic relevance of autoimmune features in IIP, the clinical importance of ANCA positivity still needs to be determined.

A 40-year-old, male non-smoker was diagnosed with asthma 6 years ago. He now presents with a 1-week history of worsening breathlessness with fever, cough, and purulent expectoration. He has had >10 emergency department visits and two admissions to hospital in the last 3 months. At each admission, he received bronchodilators and systemic steroids resulting in rapid improvement within 24 h. However, in the current presentation, the patient has no relief with corticosteroids and bronchodilators. His pulse is 140 per min, respiratory rate is 40 per min, blood pressure is 90/60 mmHg and room air oxygen saturation is 80%. Arterial blood gas (ABG) analysis shows hypercapnic respiratory failure. In view this respiratory failure, the patient is intubated and mechanical ventilation initiated. A chest radiograph is shown in figure 1. The therapy initiated includes bronchodilators, a systemic steroid, antibiotics and supportive care.

A 78-year-old male presented at the emergency room complaining of dry cough, fever up to 38.5 °C and malaise for 1 month. He had visited a general practitioner and received amoxicillin 500 mg three times a day for 7 days for a presumed chest infection, without improvement. He had a history of diabetes and arterial blood hypertension, for which he was receiving metformin 1000 mg twice a day and amlodipine 10 mg a day for 7 years. He reported no alcohol abuse and was an ex-smoker of 20 pack-years (quit 30 years ago). He had no recent hospitalisations or any medical interventions.

Professional drivers show a higher prevalence of obstructive sleep apnoea (OSA) compared with the general population. Furthermore, there is concern about the association between OSA and car crash risk given that drivers with OSA show an increased risk for car accidents. Despite this risk, OSA is often underdiagnosed and undertreated in this population, mainly due to lack of appropriate screening and sleep study referrals. Polysomnography (PSG), the gold standard test, is inappropriate for systematic screening because of its high expense, complexity and relative inaccessibility in this population. Therefore, there is a strong demand for good screening tools, including both subjective and objective data that may assist in early identification of possible OSA among professional drivers and, thus, aid in PSG examination referral and OSA management in an accredited sleep centre. However, there is considerable disagreement over screening methods and criteria for triggering a sleep study referral in different countries. There is also a strong need for further research in the area of OSA screening of commercial drivers in order to improve the diagnostic accuracy of screening tools and ensure that patients with OSA are accurately identified.

Key points

Obstructive sleep apnoea (OSA) is often undiagnosed and undertreated in professional drivers.

Professional drivers often under-report and are reluctant to report OSA symptoms.

Barriers to OSA diagnosis include appropriate screening and sleep study referrals.

Screening tools including both subjective and objective data may assist in early identification of possible OSA among professional drivers.

Educational aims

To evaluate screening instruments currently used to identify OSA risk in professional drivers.

To provide guidance for developing an assessment strategy for OSA by professional driver medical examiners.

Caseum, the central necrotic material of tuberculous lesions, is a reservoir of drug-recalcitrant persisting mycobacteria. Caseum is found in closed nodules and in open cavities connecting with an airway. Several commonly accepted characteristics of caseum were established during the preantibiotic era, when autopsies of deceased tuberculosis (TB) patients were common but methodologies were limited. These pioneering studies generated concepts such as acidic pH, low oxygen tension, and paucity of nutrients being the drivers of nonreplication and persistence in caseum. Here we review widely accepted beliefs about the caseum-specific stress factors thought to trigger the shift of Mycobacterium tuberculosis to drug tolerance. Our current state of knowledge reveals that M. tuberculosis is faced with a lipid-rich diet rather than nutrient deprivation in caseum. Variable caseum pH is seen across lesions, possibly transiently acidic in young lesions but overall near neutral in most mature lesions. Oxygen tension is low in the avascular caseum of closed nodules and high at the cavity surface, and a gradient of decreasing oxygen tension likely forms toward the cavity wall. Since caseum is largely made of infected and necrotized macrophages filled with lipid droplets, the microenvironmental conditions encountered by M. tuberculosis in foamy macrophages and in caseum bear many similarities. While there remain a few knowledge gaps, these findings constitute a solid starting point to develop high-throughput drug discovery assays that combine the right balance of oxygen tension, pH, lipid abundance, and lipid species to model the profound drug tolerance of M. tuberculosis in caseum.

Purpose:

Currently, an optimal therapeutic strategy comprising molecularly targeted agents for treating EGFR-mutated non–small cell lung cancer (NSCLC) patients with acquired resistance to osimertinib is not available. Therefore, the initial therapeutic intervention is crucial for the prolonged survival of these patients. The activation of anexelekto (AXL) signaling is known to be associated with intrinsic and acquired resistance to EGFR tyrosine kinase inhibitors (EGFR-TKIs). In this study, we investigated the best therapeutic strategy to combat AXL-induced tolerance to EGFR-TKIs using the novel AXL inhibitor ONO-7475.

Experimental Design:

We examined the efficacy of ONO-7475 in combination with EGFR-TKIs in EGFR-mutated NSCLC cells using in vitro and in vivo experiments. We investigated the correlation between AXL expression in tumors and clinical outcomes with osimertinib for EGFR-mutated NSCLC patients with acquired resistance to initial EGFR-TKIs.

Results:

ONO-7475 sensitized AXL-overexpressing EGFR-mutant NSCLC cells to the EGFR-TKIs osimertinib and dacomitinib. In addition, ONO-7475 suppressed the emergence and maintenance of EGFR-TKI–tolerant cells. In the cell line–derived xenograft models of AXL-overexpressing EGFR-mutated lung cancer treated with osimertinib, initial combination therapy of ONO-7475 and osimertinib markedly regressed tumors and delayed tumor regrowth compared with osimertinib alone or the combination after acquired resistance to osimertinib. AXL expression in EGFR-TKI refractory tumors did not correlate with the sensitivity of osimertinib.

Conclusions:

These results demonstrate that ONO-7475 suppresses the emergence and maintenance of tolerant cells to the initial EGFR-TKIs, osimertinib or dacomitinib, in AXL-overexpressing EGFR-mutated NSCLC cells, suggesting that ONO-7475 and osimertinib is a highly potent combination for initial treatment.

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.

Purpose:

The development of leptomeningeal melanoma metastases (LMM) is a rare and devastating complication of the late-stage disease, for which no effective treatments exist. Here, we performed a multi-omics analysis of the cerebrospinal fluid (CSF) from patients with LMM to determine how the leptomeningeal microenvironment shapes the biology and therapeutic responses of melanoma cells.

Experimental Design:

A total of 45 serial CSF samples were collected from 16 patients, 8 of these with confirmed LMM. Of those with LMM, 7 had poor survival (<4 months) and one was an extraordinary responder (still alive with survival >35 months). CSF samples were analyzed by mass spectrometry and incubated with melanoma cells that were subjected to RNA sequencing (RNA-seq) analysis. Functional assays were performed to validate the pathways identified.

Results:

Mass spectrometry analyses showed the CSF of most patients with LMM to be enriched for pathways involved in innate immunity, protease-mediated damage, and IGF-related signaling. All of these were anticorrelated in the extraordinary responder. RNA-seq analysis showed CSF to induce PI3K/AKT, integrin, B-cell activation, S-phase entry, TNFR2, TGFβ, and oxidative stress responses in the melanoma cells. ELISA assays confirmed that TGFβ expression increased in the CSF of patients progressing with LMM. CSF from poorly responding patients conferred tolerance to BRAF inhibitor therapy in apoptosis assays.

Conclusions:

These analyses identified proteomic/transcriptional signatures in the CSF of patients who succumbed to LMM. We further showed that the CSF from patients with LMM has the potential to modulate BRAF inhibitor responses and may contribute to drug resistance.

See related commentary by Glitza Oliva and Tawbi, p. 2083

Purpose:

Preclinical data demonstrating androgen receptor (AR)–positive (AR⁺) triple-negative breast cancer (TNBC) cells are sensitive to AR antagonists, and PI3K inhibition catalyzed an investigator-initiated, multi-institutional phase Ib/II study TBCRC032. The trial investigated the safety and efficacy of the AR-antagonist enzalutamide alone or in combination with the PI3K inhibitor taselisib in patients with metastatic AR⁺ (≥10%) breast cancer.

Patients and Methods:

Phase Ib patients [estrogen receptor positive (ER⁺) or TNBC] with AR⁺ breast cancer received 160 mg enzalutamide in combination with taselisib to determine dose-limiting toxicities and the maximum tolerated dose (MTD). Phase II TNBC patients were randomized to receive either enzalutamide alone or in combination with 4 mg taselisib until disease progression. Primary endpoint was clinical benefit rate (CBR) at 16 weeks.

Results:

The combination was tolerated, and the MTD was not reached. The adverse events were hyperglycemia and skin rash. Overall, CBR for evaluable patients receiving the combination was 35.7%, and median progression-free survival (PFS) was 3.4 months. Luminal AR (LAR) TNBC subtype patients trended toward better response compared with non-LAR (75.0% vs. 12.5%, P = 0.06), and increased PFS (4.6 vs. 2.0 months, P = 0.082). Genomic analyses revealed subtype-specific treatment response, and novel FGFR2 fusions and AR splice variants.

Conclusions:

The combination of enzalutamide and taselisib increased CBR in TNBC patients with AR⁺ tumors. Correlative analyses suggest AR protein expression alone is insufficient for identifying patients with AR-dependent tumors and knowledge of tumor LAR subtype and AR splice variants may identify patients more or less likely to benefit from AR antagonists.

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.

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.

New drugs or therapeutic combinations are urgently needed against Mycobacterium abscessus. Previously, we demonstrated the potent activity of indole-2-carboxamides 6 and 12 against M. abscessus. We show here that these compounds act synergistically with imipenem and cefoxitin in vitro and increase the bactericidal activity of the β-lactams against M. abscessus. In addition, compound 12 also displays synergism with imipenem and cefoxitin within infected macrophages. The clinical potential of these new drug combinations requires further evaluation.

Cefazolin has become a prominent therapy for methicillin-susceptible Staphylococcus aureus (MSSA) infections. However, an important concern is the cefazolin inoculum effect (CzIE), a phenomenon mediated by staphylococcal β-lactamases. Four variants of staphylococcal β-lactamases have been described based on serological methodologies and limited sequence information. Here, we sought to reassess the classification of staphylococcal β-lactamases and their correlation with the CzIE. We included a large collection of 690 contemporary bloodstream MSSA isolates recovered from Latin America, a region with a high prevalence of the CzIE. We determined cefazolin MICs at standard and high inoculums by broth microdilution. Whole-genome sequencing was performed to classify the β-lactamase in each isolate based on the predicted full sequence of BlaZ. We used the classical schemes for β-lactamase classification and compared it to BlaZ allotypes found in unique sequences using the genomic information. Phylogenetic analyses were performed based on the BlaZ and core-genome sequences. The overall prevalence of the CzIE was 40%. Among 641 genomes, type C was the most predominant β-lactamase (37%), followed by type A (33%). We found 29 allotypes and 43 different substitutions in BlaZ. A single allotype, designated BlaZ-2, showed a robust and statistically significant association with the CzIE. Two other allotypes (BlaZ-3 and BlaZ-5) were associated with a lack of the CzIE. Three amino acid substitutions (A9V, E112A, and G145E) showed statistically significant association with the CzIE (P = <0.01). CC30 was the predominant clone among isolates displaying the CzIE. Thus, we provide a novel approach to the classification of the staphylococcal β-lactamases with the potential to more accurately identify MSSA strains exhibiting the CzIE.

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 (MIC_50/90, 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 (MIC_50/90, 0.06/0.12 mg/liter), viridans group streptococci (MIC_50/90, 0.06/0.12 mg/liter), and beta-hemolytic streptococci (MIC_50/90, 0.12/0.25 mg/liter), regardless of species and susceptibility to penicillin, macrolides, or tetracycline. Omadacycline was active against all Enterobacterales tested (MIC_50/90, 1/8 mg/liter; 87.5% of isolates were inhibited at ≤4 mg/liter) except Proteus mirabilis (MIC_50/90, 16/>32 mg/liter) and indole-positive Proteus spp. (MIC_50/90, 8/32 mg/liter) and was most active against Escherichia coli (MIC_50/90, 0.5/2 mg/liter), Klebsiella oxytoca (MIC_50/90, 1/2 mg/liter), and Citrobacter spp. (MIC_50/90, 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 (MIC_50/90, 0.5/1 mg/liter), regardless of β-lactamase status, and against Moraxella catarrhalis (MIC_50/90, ≤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.

Doxycycline, an FDA-approved tetracycline, is used in tuberculosis in vivo models for the temporal control of mycobacterial gene expression. In these models, animals are infected with recombinant Mycobacterium tuberculosis carrying genes of interest under transcriptional control of the doxycycline-responsive TetR-tetO unit. To minimize fluctuations of plasma levels, doxycycline is usually administered in the diet. However, tissue penetration studies to identify the minimum doxycycline content in food achieving complete repression of TetR-controlled genes in tuberculosis (TB)-infected organs and lesions have not been conducted. Here, we first determined the tetracycline concentrations required to achieve silencing of M. tuberculosis target genes in vitro. Next, we measured doxycycline concentrations in plasma, major organs, and lung lesions in TB-infected mice and rabbits and compared these values to silencing concentrations measured in vitro. We found that 2,000 ppm doxycycline supplemented in mouse and rabbit feed is sufficient to reach target concentrations in TB lesions. In rabbit chow, the calcium content had to be reduced 5-fold to minimize chelation of doxycycline and deliver adequate oral bioavailability. Clearance kinetics from major organs and lung lesions revealed that doxycycline levels fall below concentrations that repress tet promoters within 7 to 14 days after doxycycline is removed from the diet. In summary, we have shown that 2,000 ppm doxycycline supplemented in standard mouse diet and in low-calcium rabbit diet delivers concentrations adequate to achieve full repression of tet promoters in infected tissues of mice and rabbits.

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.

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.

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.

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 (MIC_50/90, 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.

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.)

Increasing numbers of variants of the carbapenem-hydrolyzing class D β-lactamase OXA-48 are identified in Enterobacterales worldwide. Among them, OXA-181 and OXA-232 are of particular interest, as they differ from each other by a single amino acid substitution at position 214 (R in OXA-181 and S in OXA-232) that results in reduced carbapenem-hydrolyzing activity for OXA-232. To investigate the role of amino acid position 214 (AA214), the X-ray structure of OXA-232 was determined and AA214 of OXA-48 and of OXA-232 was replaced by G, L, D, E, S, R, and K using site-directed mutagenesis. These mutants were phenotypically characterized, and three mutants of OXA-232 were purified to study their steady-state kinetic properties. The X-ray structure of OXA-232 along with molecular modeling studies showed that the interaction via a salt bridge between R214 and D159 in OXA-48 is not possible with the G214 or S214 mutation. In contrast, with K214, which is also positively charged, the interaction with D159 is maintained. With the E214 mutant, an alternative binding conformation of imipenem that is not compatible with a nucleophilic attack by S70 was evidenced. Thus, imipenem has a very poor apparent affinity for the E214 mutant because of its nonproductive binding mode. Similarly, we could explain the lack of temocillin hydrolysis by the OXA-232-S214E mutant, which is due to the unfavorable interaction between the negatively charged R1 substituent of temocillin with the E214 residue. Overall, we demonstrate that AA214 in OXA-48-like β-lactamases is critical for the carbapenemase activity.

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.

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.)

Carbapenem resistance in Enterobacterales is a public health threat. Klebsiella pneumoniae carbapenemase (encoded by alleles of the bla_KPC family) is one of the most common transmissible carbapenem resistance mechanisms worldwide. The dissemination of bla_KPC historically has been associated with distinct K. pneumoniae lineages (clonal group 258 [CG258]), a particular plasmid family (pKpQIL), and a composite transposon (Tn4401). In the United Kingdom, bla_KPC has represented a large-scale, persistent management challenge for some hospitals, particularly in North West England. The dissemination of bla_KPC has evolved to be polyclonal and polyspecies, but the genetic mechanisms underpinning this evolution have not been elucidated in detail; this study used short-read whole-genome sequencing of 604 bla_KPC-positive isolates (Illumina) and long-read assembly (PacBio)/polishing (Illumina) of 21 isolates for characterization. We observed the dissemination of bla_KPC (predominantly bla_KPC-2; 573/604 [95%] isolates) across eight species and more than 100 known sequence types. Although there was some variation at the transposon level (mostly Tn4401a, 584/604 [97%] isolates; predominantly with ATTGA-ATTGA target site duplications, 465/604 [77%] isolates), bla_KPC spread appears to have been supported by highly fluid, modular exchange of larger genetic segments among plasmid populations dominated by IncFIB (580/604 isolates), IncFII (545/604 isolates), and IncR (252/604 isolates) replicons. The subset of reconstructed plasmid sequences (21 isolates, 77 plasmids) also highlighted modular exchange among non-bla_KPC and bla_KPC plasmids and the common presence of multiple replicons within bla_KPC plasmid structures (>60%). The substantial genomic plasticity observed has important implications for our understanding of the epidemiology of transmissible carbapenem resistance in Enterobacterales for the implementation of adequate surveillance approaches and for control.

Animal models of bacterial infection have been widely used to explore the in vivo activity of antibacterial drugs. These data are often submitted to the U.S. Food and Drug Administration to support human use in an investigational new drug application (IND). To better understand the range and scientific use of animal models in regulatory submissions, a database was created surveying recent pneumonia models submitted as part of IND application packages. The IND studies were compared to animal models of bacterial pneumonia published in the scientific literature over the same period of time. In this review, we analyze the key experimental design elements, such as animal species, immune status, pathogens selected, and route of administration, and study endpoints.

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.