An expanded universe of cancer targets.

The characterization of cancer genomes has provided insight into somatically altered genes across tumors, transformed our understanding of cancer biology, and enabled tailoring of therapeutic strategies. However, the function of most cancer alleles remains mysterious, and many cancer features transcend their genomes. Consequently, tumor genomic characterization does not influence therapy for most patients. Approaches to understand the function and circuitry of cancer genes provide complementary approaches to elucidate both oncogene and non-oncogene dependencies. Emerging work indicates that the diversity of therapeutic targets engendered by non-oncogene dependencies is much larger than the list of recurrently mutated genes. Here we describe a framework for this expanded list of cancer targets, providing novel opportunities for clinical translation.

A Hematogenous Route for Medulloblastoma Leptomeningeal Metastases.

While the preponderance of morbidity and mortality in medulloblastoma patients are due to metastatic disease, most research focuses on the primary tumor due to a dearth of metastatic tissue samples and model systems. Medulloblastoma metastases are found almost exclusively on the leptomeningeal surface of the brain and spinal cord; dissemination is therefore thought to occur through shedding of primary tumor cells into the cerebrospinal fluid followed by distal re-implantation on the leptomeninges. We present evidence for medulloblastoma circulating tumor cells (CTCs) in therapy-naive patients and demonstrate in vivo, through flank xenografting and parabiosis, that medulloblastoma CTCs can spread through the blood to the leptomeningeal space to form leptomeningeal metastases. Medulloblastoma leptomeningeal metastases express high levels of the chemokine CCL2, and expression of CCL2 in medulloblastoma in vivo is sufficient to drive leptomeningeal dissemination. Hematogenous dissemination of medulloblastoma offers a new opportunity to diagnose and treat lethal disseminated medulloblastoma.

Brain-restricted mTOR inhibition with binary pharmacology.

On-target-off-tissue drug engagement is an important source of adverse effects that constrains the therapeutic window of drug candidates1,2. In diseases of the central nervous system, drugs with brain-restricted pharmacology are highly desirable. Here we report a strategy to achieve inhibition of mammalian target of rapamycin (mTOR) while sparing mTOR activity elsewhere through the use of the brain-permeable mTOR inhibitor RapaLink-1 and the brain-impermeable FKBP12 ligand RapaBlock. We show that this drug combination mitigates the systemic effects of mTOR inhibitors but retains the efficacy of RapaLink-1 in glioblastoma xenografts. We further present a general method to design cell-permeable, FKBP12-dependent kinase inhibitors from known drug scaffolds. These inhibitors are sensitive to deactivation by RapaBlock, enabling the brain-restricted inhibition of their respective kinase targets.

Recurrent noncoding U1 snRNA mutations drive cryptic splicing in SHH medulloblastoma.

In cancer, recurrent somatic single-nucleotide variants-which are rare in most paediatric cancers-are confined largely to protein-coding genes1-3. Here we report highly recurrent hotspot mutations (r.3A>G) of U1 spliceosomal small nuclear RNAs (snRNAs) in about 50% of Sonic hedgehog (SHH) medulloblastomas. These mutations were not present across other subgroups of medulloblastoma, and we identified these hotspot mutations in U1 snRNA in only <0.1% of 2,442 cancers, across 36 other tumour types. The mutations occur in 97% of adults (subtype SHHδ) and 25% of adolescents (subtype SHHα) with SHH medulloblastoma, but are largely absent from SHH medulloblastoma in infants. The U1 snRNA mutations occur in the 5' splice-site binding region, and snRNA-mutant tumours have significantly disrupted RNA splicing and an excess of 5' cryptic splicing events. Alternative splicing mediated by mutant U1 snRNA inactivates tumour-suppressor genes (PTCH1) and activates oncogenes (GLI2 and CCND2), and represents a target for therapy. These U1 snRNA mutations provide an example of highly recurrent and tissue-specific mutations of a non-protein-coding gene in cancer.

Glioblastoma cellular cross-talk converges on NF-κB to attenuate EGFR inhibitor sensitivity.

In glioblastoma (GBM), heterogeneous expression of amplified and mutated epidermal growth factor receptor (EGFR) presents a substantial challenge for the effective use of EGFR-directed therapeutics. Here we demonstrate that heterogeneous expression of the wild-type receptor and its constitutively active mutant form, EGFRvIII, limits sensitivity to these therapies through an interclonal communication mechanism mediated by interleukin-6 (IL-6) cytokine secreted from EGFRvIII-positive tumor cells. IL-6 activates a NF-κB signaling axis in a paracrine and autocrine manner, leading to bromodomain protein 4 (BRD4)-dependent expression of the prosurvival protein survivin (BIRC5) and attenuation of sensitivity to EGFR tyrosine kinase inhibitors (TKIs). NF-κB and survivin are coordinately up-regulated in GBM patient tumors, and functional inhibition of either protein or BRD4 in in vitro and in vivo models restores sensitivity to EGFR TKIs. These results provide a rationale for improving anti-EGFR therapeutic efficacy through pharmacological uncoupling of a convergence point of NF-κB-mediated survival that is leveraged by an interclonal circuitry mechanism established by intratumoral mutational heterogeneity.

Heterozygous ANKRD17 loss-of-function variants cause a syndrome with intellectual disability, speech delay, and dysmorphism.

ANKRD17 is an ankyrin repeat-containing protein thought to play a role in cell cycle progression, whose ortholog in Drosophila functions in the Hippo pathway as a co-factor of Yorkie. Here, we delineate a neurodevelopmental disorder caused by de novo heterozygous ANKRD17 variants. The mutational spectrum of this cohort of 34 individuals from 32 families is highly suggestive of haploinsufficiency as the underlying mechanism of disease, with 21 truncating or essential splice site variants, 9 missense variants, 1 in-frame insertion-deletion, and 1 microdeletion (1.16 Mb). Consequently, our data indicate that loss of ANKRD17 is likely the main cause of phenotypes previously associated with large multi-gene chromosomal aberrations of the 4q13.3 region. Protein modeling suggests that most of the missense variants disrupt the stability of the ankyrin repeats through alteration of core structural residues. The major phenotypic characteristic of our cohort is a variable degree of developmental delay/intellectual disability, particularly affecting speech, while additional features include growth failure, feeding difficulties, non-specific MRI abnormalities, epilepsy and/or abnormal EEG, predisposition to recurrent infections (mostly bacterial), ophthalmological abnormalities, gait/balance disturbance, and joint hypermobility. Moreover, many individuals shared similar dysmorphic facial features. Analysis of single-cell RNA-seq data from the developing human telencephalon indicated ANKRD17 expression at multiple stages of neurogenesis, adding further evidence to the assertion that damaging ANKRD17 variants cause a neurodevelopmental disorder.

Phenytoin is associated with increased risk of osteoporosis and fragility fractures in adult epileptic patients.

INTRODUCTION: Osteoporotic fractures lead to significant decreases in the quality of life with increases in morbidity, mortality, and disability. Treatment with a variety of anti-epileptic drugs, such as phenytoin, has been understood to cause a decrease in bone mineral density. MATERIALS AND METHODS: Cohort A was identified as patients that were 18-55 years old that had epilepsy and recurrent seizures that were also prescribed phenytoin. Cohort B was identified as patients that were 18-55 years old that had epilepsy and recurrent seizures but were not prescribed phenytoin or other anti-epileptic medications. Cohorts were matched for relevant confounding pathologies and demographic factors. Outcomes were evaluated from 1 day to 5 years after the indexed event. RESULTS: A total of 35,936 patients with epilepsy that were prescribed phenytoin were matched with 109,335 patients with epilepsy that were not prescribed phenytoin. Patients on phenytoin therapy were at significantly higher risk for osteoporosis without pathological fracture, fracture of metatarsal bone, fracture of shoulder and upper arm, fracture of distal radius, fracture of thoracic vertebra, fracture of cervical vertebra, fracture of lumbar vertebra, fracture of femoral head or neck, pertrochanteric fracture, femoral shaft fracture, and distal tibia fracture (all outcomes p < 0.001). CONCLUSION: Epileptic patients on phenytoin therapy that were 18-55 years old exhibited higher associated risk of osteoporosis and osteoporotic-fragility fractures of various regions. Patients that undergo phenytoin therapy for epilepsy treatment should be educated on the increased risk of bone fractures and have appropriate lifestyle and diet modifications.

Fluid Dynamic Study of the Penn State Pediatric Total Artificial Heart.

Penn State University is developing a pediatric total artificial heart (TAH) as a bridge-to-transplant device that supports infants and small children with single ventricle anomalies or biventricular heart failure to address high waitlist mortality rates for pediatric patients with severe congenital heart disease (CHD). Two issues with mechanical circulatory support devices are thrombus formation and thromboembolic events. This in vitro study characterizes flow within Penn State's pediatric total artificial heart under physiological operating conditions. Particle image velocimetry (PIV) is used to quantify flow within the pump and to calculate wall shear rates (WSRs) along the internal pump surface to identify potential thrombogenic regions. Results show that the diastolic inflow jets produce sufficient wall shear rates to reduce thrombus deposition potential along the inlet side of the left and right pumps. The inlet jet transitions to rotational flow, which promotes wall washing along the apex of the pumps, prevents flow stasis, and aligns flow with the outlet valve prior to systolic ejection. However, inconsistent high wall shear rates near the pump apex cause increased thrombogenic potential. Strong systolic outflow jets produce high wall shear rates near the outlet valve to reduce thrombus deposition risk. The right pump, which has a modified outlet port angle to improve anatomical fit, produces lower wall shear rates and higher thrombus susceptibility potential (TSP) compared to the left pump. In summary, this study provides a fluid dynamic understanding of a new pediatric total artificial heart and indicates thrombus susceptibility is primarily confined to the apex, consistent with similar pulsatile heart pumps.

Risk Factors Associated With Postoperative Cardiac Events Following Total Hip and Knee Arthroplasty.

BACKGROUND: This study investigated the prevalence of adverse cardiac events following a total joint arthroplasty and subsequently analyzed risk factors that may increase the likelihood of these events. METHODS: Data for this study were extracted from a large national database. Chi-squared analyses and multivariate modelings were performed to determine the risk factors associated with 30-day perioperative troponin elevation, myocardial infarction (MI), and heart failure. We identified 80,544 total hip arthroplasty (THA) patients and 112,531 total knee arthroplasty (TKA) patients and analyzed the following cardiac risk factors: diabetes, renal insufficiency, prior MI, hypertension, and cerebrovascular disease. RESULTS: There were 34% of THA patients and 52% of TKA patients who had at least one of the studied risk factors. At-risk THA patients had 2.2, 5.9, and 5.3 times the odds of troponin elevation, MI, and postoperative heart failure, respectively, within 1 month compared to the control group (P < .0001). The TKA group had 2.9, 5.3, and 5.9 times the odds of troponin elevation, MI, and postoperative heart failure within 1 month compared to the control group (P < .0001). For both procedures, prior MI had the highest odds of resulting in perioperative troponin elevation and MI. Renal insufficiency had the highest odds of resulting in perioperative heart failure. CONCLUSIONS: Risk stratification for postoperative complications in orthopedic surgery is important to minimize adverse outcomes. This study highlights the need for consideration of risk factors prior to joint arthroplasty surgery. LEVEL OF EVIDENCE: Level III, Prognostic.

Area-specific covid-19 effects on health services utilization in the Democratic Republic of the Congo using routine health information system data.

BACKGROUND: Since March 2020, the COVID-19 pandemic has shocked health systems worldwide. This analysis investigated the effects of the pandemic on basic health services utilization in the Democratic Republic of the Congo (DRC) and examined the variability of COVID effects in the capital city Kinshasa, in other urban areas, and in rural areas. METHODS: We estimated time trends models using national health information system data to replicate pre-COVID-19 (i.e., January 2017-February 2020) trajectories of health service utilization, and then used those models to estimate what the levels would have been in the absence of COVID-19 during the pandemic period, starting in March 2020 through March 2021. We classified the difference between the observed and predicted levels as the effect of COVID-19 on health services. We estimated 95% confidence intervals and p-values to examine if the effect of the pandemic, nationally and within specific geographies, was statistically significant. RESULTS: Our results indicate that COVID-19 negatively impacted health services and subsequent recovery varied by service type and by geographical area. COVID-19 had a lasting impact on overall service utilization as well as on malaria and pneumonia-related visits among young children in the DRC. We also found that the effects of COVID-19 were even more immediate and stronger in the capital city of Kinshasa compared with the national effect. Both nationally and in Kinshasa, most affected services had slow and incomplete recovery to expected levels. Therefore, our analysis indicates that COVID-19 continued to affect health services in the DRC throughout the first year of the pandemic. CONCLUSIONS: The methodology used in this article allows for examining the variability in magnitude, timing, and duration of the COVID effects within geographical areas of the DRC and nationally. This analytical procedure based on national health information system data could be applied to surveil health service disruptions and better inform rapid responses from health service managers and policymakers.

A comparison of approaches to measuring maternal mortality in Bangladesh, Mozambique, and Bolivia.

BACKGROUND: Many low- and middle-income countries cannot measure maternal mortality to monitor progress against global and country-specific targets. While the ultimate goal for these countries is to have complete civil registrations systems, other interim strategies are needed to provide timely estimates of maternal mortality. OBJECTIVE: The objective is to inform on potential options for measuring maternal mortality. METHODS: This paper uses a case study approach to compare methodologies and estimates of pregnancy-related mortality ratio (PRMR)/maternal mortality ratio (MMR) obtained from four different data sources from similar time periods in Bangladesh, Mozambique, and Bolivia-national population census; post-census mortality survey; household sample survey; and sample vital registration system (SVRS). RESULTS: For Bangladesh, PRMR from the 2011 census falls closely in line with the 2010 household survey and SVRS estimates, while SVRS' MMR estimates are closer to the PRMR estimates obtained from the household survey. Mozambique's PRMR from household survey method is comparable and shows an upward trend between 1994 and 2011, whereas the post-census mortality survey estimated a higher MMR for 2007. Bolivia's DHS and post-census mortality survey also estimated comparable MMR during 1998-2003. CONCLUSIONS: Overall all these data sources presented in this paper have provided valuable information on maternal mortality in Bangladesh, Mozambique, and Bolivia. It also outlines recommendations to estimate maternal mortality based on the advantages and disadvantages of several approaches. CONTRIBUTION: Recommendations in this paper can help health administrators and policy planners in prioritizing investment for collecting reliable and contemporaneous estimates of maternal mortality while progressing toward a complete civil registration system.

Estimating the impact of donor programs on child mortality in low- and middle-income countries: a synthetic control analysis of child health programs funded by the United States Agency for International Development.

BACKGROUND: Significant levels of funding have been provided to low- and middle-income countries for development assistance for health, with most funds coming through direct bilateral investment led by the USA and the UK. Direct attribution of impact to large-scale programs funded by donors remains elusive due the difficulty of knowing what would have happened without those programs, and the lack of detailed contextual information to support causal interpretation of changes. METHODS: This study uses the synthetic control analysis method to estimate the impact of one donor's funding (United States Agency for International Development, USAID) on under-five mortality across several low- and middle-income countries that received above average levels of USAID funding for maternal and child health programs between 2000 and 2016. RESULTS: In the study period (2000-16), countries with above average USAID funding had an under-five mortality rate lower than the synthetic control by an average of 29 deaths per 1000 live births (year-to-year range of - 2 to - 38). This finding was consistent with several sensitivity analyses. CONCLUSIONS: The synthetic control method is a valuable addition to the range of approaches for quantifying the impact of large-scale health programs in low- and middle-income countries. The findings suggest that adequately funded donor programs (in this case USAID) help countries to reduce child mortality to significantly lower rates than would have occurred without those investments.

Causes of deaths in neonates and children aged 1-59 months in Nigeria: verbal autopsy findings of 2019 Verbal and Social Autopsy study.

BACKGROUND: Nigeria has one of the highest under-five mortality rates in the world. Identifying the causes of these deaths is crucial to inform changes in policy documents, design and implementation of appropriate interventions to reduce these deaths. This study aimed to provide national and zonal-level estimates of the causes of under-five death in Nigeria in the 2013-2018 periods. METHODS: We conducted retrospective inquiries into the cause of deaths of 948 neonates and 2,127 children aged 1-59 months as identified in the 2018 Nigeria Demographic and Health Survey (NDHS). The verbal autopsy asked about signs and symptoms during the final illness. The Physician Coded Verbal Autopsy (PCVA) and Expert Algorithm Verbal Autopsy (EAVA) methods were employed to assign the immediate and underlying cause of deaths to all cases. RESULT: For the analysis, sampling weights were applied to accommodate non-proportional allocation. Boys accounted for 56 percent of neonatal deaths and 51.5 percent of the 1-59-months old deaths. About one-quarter of under-5 mortality was attributed to neonatal deaths, and 50 percent of these neonatal deaths were recorded within 48 h of delivery. Overall, 84 percent of the under-5 deaths were in the northern geopolitical zones. Based on the two methods for case analysis, neonatal infections (sepsis, pneumonia, and meningitis) were responsible for 44 percent of the neonatal deaths, followed by intrapartum injury (PCVA: 21 percent vs. EAVA: 29 percent). The three main causes of death in children aged 1-59 months were malaria (PCVA: 23 percent vs. EAVA: 35 percent), diarrhoea (PCVA: 17 percent vs. EAVA: 23 percent), and pneumonia (PCVA: 10 percent vs. EAVA: 12 percent). In the North West, where the majority of under-5 (1-59 months) deaths were recorded, diarrhoea was the main cause of death (PCVA: 24.3 percent vs. EAVA: 30 percent). CONCLUSION: The causes of neonatal and children aged 1-59 months deaths vary across the northern and southern regions. By homing on the specific causes of mortality by region, the study provides crucial information that may be useful in planning appropriately tailored interventions to significantly reduce under-five deaths in Nigeria.

Health beliefs and (timely) use of facility-based care for under-five children: lessons from the qualitative component of Nigeria's 2019 VASA.

BACKGROUND: Nigeria's under-five health outcomes have improved over the years, but the mortality rates remain unacceptably high. The qualitative component of Nigeria's 2019 verbal and social autopsy (VASA) showed that caregivers' health beliefs about causes of illnesses and efficacious treatment options contribute to non-use/delay in use of facility-based healthcare for under-five children. This study explored how these health beliefs vary across zones and how they shape how caregivers seek healthcare for their under-five children. METHODS: Data for this study come from the qualitative component of the 2019 Nigeria VASA, comprising 69 interviews with caregivers of under-five children who died in the five-year period preceding the 2018 Nigeria Demographic and Health Survey (NDHS); and 24 key informants and 48 focus group discussions (FGDs) in 12 states, two from each of the six geo-political zones. The transcripts were coded using predetermined themes on health beliefs from the 2019 VASA (qualitative component) using NVivo. RESULTS: The study documented zonal variation in belief in traditional medicine, biomedicine, spiritual causation of illnesses, syncretism, and fatalism, with greater prevalence of beliefs discouraging use of facility-based healthcare in the southern zones. Driven by these beliefs and factors such as availability, affordability, and access to and perceived quality of care in health facilities, caregivers often choose one or a combination of traditional medicines, care from medicine vendors, and faith healing. Most use facility-based care as the last option when other methods fail. CONCLUSION: Caregivers' health beliefs vary by zones, and these beliefs influence when and whether they will use facility-based healthcare services for their under-five children. In Nigeria's northern zones, health beliefs are less likely to deter caregivers from using facility-based healthcare services, but they face other barriers to accessing facility-based care. Interventions seeking to reduce under-five deaths in Nigeria need to consider subnational differences in caregivers' health beliefs and the healthcare options they choose based on those beliefs.

Experimental Hemodynamics Within the Penn State Fontan Circulatory Assist Device.

For children born with a single functional ventricle, the Fontan operation bypasses the right ventricle by forming a four-way total cavopulmonary connection and adapts the existing ventricle for the systemic circulation. However, upon reaching adulthood, many Fontan patients exhibit low cardiac output and elevated venous pressure, eventually requiring a heart transplantation. Despite efforts in developing a new device or using an existing device for failing Fontan support, there is still no Food and Drug Administration-approved device for subpulmonary support. Penn State University is developing a hydrodynamically levitated Fontan circulatory assist device (FCAD) for bridge-to-transplant or destination therapy. The hemodynamics within the FCAD, at both steady and patient averaged pulsatile conditions for three physiological pump operating conditions, were quantified using particle image velocimetry (PIV) to determine the velocity magnitudes and Reynolds normal and shear stresses within the device. Data were acquired at three planes (0 mm and ±25% of the radius) for the inferior and superior vena cavae inlets and the pulmonary artery outlet. The inlets had a blunt velocity profile that became skewed toward the collecting volute as fluid approached the rotor. At the outlet, regardless of the flow condition, a high-velocity jet exited the volute and moved downstream in a helical pattern. Turbulent stresses observed at the volute exit were influenced by the rotor's rotation. Regardless of inlet conditions, the pump demonstrated advantageous behavior for clinical use with a predictable flow field and a low risk of platelet adhesion and hemolysis based on calculated wall shear rates and turbulent stresses, respectively.

Publication Trends of Residents Accepted for Shoulder and Elbow Fellowships.

This study aims to evaluate the research productivity trends in orthopaedic residents who were selected for shoulder and elbow fellowships from 2010 to 2019. We hypothesize that residents matching into orthopaedic shoulder and elbow fellowships are increasing both their publication number and publication quality from 2010 to 2019. Fellows of orthopaedic shoulder and elbow programs from 2010 to 2019 were identified through publicly accessible information on fellowship programs. Each fellow's publication data during their residency was collected via publicly available search engines, and analyzed to include: fellowship year, residency years, fellowship program and location, total publications, number of publications in high-impact general orthopaedic and shoulder and elbow journals, and authorship position. A total of 176 orthopaedic shoulder and elbow fellows from 17 different programs were identified and included in the study. The fellows produced a total of 668 publications, published 172 articles in high impact journals, and had first authorship on 49% of the studies. On average, there were 3.8 publications per fellow per year from 2010 to 2019. There were 5.7 publications produced per fellow in 2018-2019, compared to just 2.92 publications per fellow in 2010-2011. Overall, there was an increasing trend in publications, publications in high impact journals, and first authorship publications per applicant matching into shoulder and elbow fellowship from 2010 to 2019. (Journal of Surgical Orthopaedic Advances 31(4):205-208, 2022).

Oral Immunotherapy With Human Secretory Immunoglobulin A Improves Survival in the Hamster Model of Clostridioides difficile Infection.

Coadministration of human secretory IgA (sIgA) together with subtherapeutic vancomycin enhanced survival in the Clostridioides difficile infection (CDI) hamster model. Vancomycin (5 or 10 mg/kg × 5 days) plus healthy donor plasma sIgA/monomeric IgA (TID × 21 days) or hyperimmune sIgA/monomeric IgA (BID × 13 days) enhanced survival. Survival was improved compared to vancomycin alone, P = .018 and .039 by log-rank Mantel-Cox, for healthy and hyperimmune sIgA, respectively. Passive immunization with sIgA (recombinant human secretory component plus IgA dimer/polymer from pooled human plasma) can be administered orally and prevents death in a partially treated CDI hamster model.

Pseudomonas aeruginosa Ventilator-Associated Pneumonia Rabbit Model for Preclinical Drug Development.

Development and validation of large animal models of Pseudomonas aeruginosa ventilator-associated pneumonia are needed for testing new drug candidates in a manner that mimics how they will be used clinically. We developed a new model in which rabbits were ventilated with low tidal volume and challenged with P. aeruginosa to recapitulate hallmark clinical features of acute respiratory distress syndrome (ARDS): acute lung injury and inflammation, progressive decrease in arterial oxygen partial pressure to fractional inspired oxygen PaO2:FiO2, leukopenia, neutropenia, thrombocytopenia, hyperlactatemia, severe hypotension, bacterial dissemination from lung to other organs, multiorgan dysfunction, and ultimately death. We evaluated the predictive power of this rabbit model for antibiotic efficacy testing by determining whether a humanized dosing regimen of meropenem, a potent antipseudomonal ß-lactam antibiotic, when administered with or without intensive care unit (ICU)-supportive care (fluid challenge and norepinephrine), could halt or reverse natural disease progression. Our humanized meropenem dosing regimen produced a plasma concentration-time profile in the rabbit model similar to those reported in patients with ventilator-associated bacterial pneumonia. In this rabbit model, treatment with humanized meropenem and ICU-supportive care achieved the highest level of survival, halted the worsening of ARDS biomarkers, and reversed lethal hypotension, although treatment with humanized meropenem alone also conferred some protection compared to treatment with placebo (saline) alone or placebo plus ICU-supportive care. In conclusion, this rabbit model could help predict whether an antibiotic will be efficacious for the treatment of human ventilator-associated pneumonia.

Microbiological Characterization of VNRX-5236, a Broad-Spectrum ß-Lactamase Inhibitor for Rescue of the Orally Bioavailable Cephalosporin Ceftibuten as a Carbapenem-Sparing Agent against Strains of Enterobacterales Expressing Extended-Spectrum ß-Lactamases and Serine Carbapenemases.

There is an urgent need for oral agents to combat resistant Gram-negative pathogens. Here, we describe the characterization of VNRX-5236, a broad-spectrum boronic acid ß-lactamase inhibitor (BLI), and its orally bioavailable etzadroxil prodrug, VNRX-7145. VNRX-7145 is being developed in combination with ceftibuten, an oral cephalosporin, to combat strains of Enterobacterales expressing extended-spectrum ß-lactamases (ESBLs) and serine carbapenemases. VNRX-5236 is a reversible covalent inhibitor of serine ß-lactamases, with inactivation efficiencies on the order of 104 M-1 · sec-1, and prolonged active site residence times (t1/2, 5 to 46 min). The spectrum of inhibition includes Ambler class A ESBLs, class C cephalosporinases, and class A and D carbapenemases (KPC and OXA-48, respectively). Rescue of ceftibuten by VNRX-5236 (fixed at 4 µg/ml) in isogenic strains of Escherichia coli expressing class A, C, or D ß-lactamases demonstrated an expanded spectrum of activity relative to oral comparators, including investigational penems, sulopenem, and tebipenem. VNRX-5236 rescued ceftibuten activity in clinical isolates of Enterobacterales expressing ESBLs (MIC90, 0.25 µg/ml), KPCs (MIC90, 1 µg/ml), class C cephalosporinases (MIC90, 1 µg/ml), and OXA-48-type carbapenemases (MIC90, 1 µg/ml). Frequency of resistance studies demonstrated a low propensity for recovery of resistant variants at 4× the MIC of the ceftibuten/VNRX-5236 combination. In vivo, whereas ceftibuten alone was ineffective (50% effective dose [ED50], >128 mg/kg), ceftibuten/VNRX-7145 administered orally protected mice from lethal septicemia caused by Klebsiella pneumoniae producing KPC carbapenemase (ED50, 12.9 mg/kg). The data demonstrate potent, broad-spectrum rescue of ceftibuten activity by VNRX-5236 in clinical isolates of cephalosporin-resistant and carbapenem-resistant Enterobacterales.