Clinical outcomes of female external urine wicking devices as alternatives to indwelling catheters: a systematic review and meta-analysis.

BACKGROUND: Female patients using indwelling urinary catheters (IUCs) are disproportionately at risk for developing catheter-associated urinary tract infections (CAUTIs) compared to males. Female external urine wicking devices (FEUWDs) have emerged as potential alternatives to IUCs for incontinence management. OBJECTIVES: To assess the clinical risks and benefits of FEUWDs as alternatives to IUCs. METHODS: Ovid MEDLINE, Embase, Scopus, Web of Science Core Collection, CINAHL Complete, and ClinicalTrials.gov were searched from inception to July 10, 2023. Included studies used FEUWDs as an intervention and reported measures of urinary tract infections and secondary outcomes related to incontinence management. RESULTS: Of 2,580 returned records, 50 were systematically reviewed. Meta-analyses assessed rates of indwelling CAUTIs and IUC utilization. Following FEUWD implementation, IUC utilization rates decreased 14% (RR = 0.86, 95% CI = [0.76, 0.97]) and indwelling CAUTI rates nonsignificantly decreased up to 32% (IRR = 0.68, 95% CI = [0.39, 1.17]). Limited only to studies that described protocols for implementation, the incidence rate of indwelling CAUTIs decreased significantly up to 54% (IRR = 0.46, 95% CI = [0.32, 0.66]). Secondary outcomes were reported less routinely. CONCLUSIONS: Overall, FEUWDs nonsignificantly reduced indwelling CAUTI rates, though reductions were significant among studies describing FEUWD implementation protocols. We recommend developing standard definitions for consistent reporting of non-indwelling CAUTI complications such as FEUWD-associated UTIs, skin injuries, and mobility-related complications.

Exploring Information Seeking Anxiety Among Localized Prostate Cancer Patients.

Information seeking anxiety is a multidimensional construct that is operationalized as having elements of worry, confusion, and disorganization. Much remains unknown about the ways information seeking anxiety operates among cancer patients in the United States. This study investigated the application of the information seeking anxiety concept among prostate cancer patients by documenting their assessment experiences and examining relationships between information seeking anxiety and treatment information search behaviors. A purposive sample of African American and Caucasian men (N = 63) within 5 years of being diagnosed with localized disease (stage T1 or T2) were recruited to participate through cancer registries, advertisements, and word-of-mouth. Participants completed a self-administered survey with items that collected demographic information, treatment information-seeking behaviors, and information seeking anxiety evaluations. All surveys were completed in one sitting and a majority of men (82.5%, N = 52) completed the information seeking anxiety assessment with no assistance. During their first interactions with available sources of information (e.g., doctors, internet, peers), most survivors (95.2%, N = 60) reported some level of information seeking anxiety. Specifically, 55.5% (N = 35) were confused about what to look for, 60.3% (N = 38) were worried they would not find the right information, 55.5% (N = 35) were uncomfortable with the search process, and 49.2% (N = 31) reported being disorganized. The composite information seeking anxiety measure was moderately correlated with men's self-reported time to start searching for treatment information (p = .02; r = .306). Information seeking anxiety appears to delay the treatment information gathering activities of prostate cancer survivors with localized disease. This previously undocumented barrier to the delivery of prostate cancer care services should be investigated in other studies with larger and more diverse samples.

The contextual interview: a cross-cutting patient-interviewing approach for social context.

Patient interviewing pedagogy in medical education has not evolved to comprehensively capture the biopsychosocial model of healthcare delivery. While gathering a patient's social history targets important aspects of social context it does not adequately capture and account for the real-time reassessment required to understand evolving factors that influence exposure to drivers of health inequities, social determinants of health, and access to supports that promote health. The authors offer a patient interviewing approach called the Contextual Interview (CI) that specifically targets dynamic and ever-changing social context information. To substantiate the use of the CI in medical education, the authors conducted a qualitative review of the Accreditation Council for Graduate Medical Education Milestones for primary care specialties (Family Medicine, Internal Medicine, and Pediatrics). Milestones were coded to the extent to which they reflected the learner's need to acknowledge, assess, synthesize and/or apply patient contextual data in real-time patient encounters. Approximately 1 in 5 milestones met the context-related and patient-facing criteria. This milestone review further highlights the need for more intentional training in eliciting meaningful social context data during patient interviewing. The CI as a cross-cutting, practical, time-conscious, and semi-structured patient interviewing approach that deliberately elicits information to improve the clinician's sense and understanding of a patient's social context. The authors reviewed future directions in researching adapted versions of the CI for undergraduate and graduate medical education.

Adherence to recommended guidelines for low back pain presentations to an Australian emergency department: Barriers and enablers.

OBJECTIVE: This study sought to evaluate the adherence to guidelines for the management of mechanical Low Back Pain within a single tertiary metropolitan Emergency Department setting. Our objectives were: METHODS: A two-stage multi-methods study design was undertaken. Stage 1 involved a retrospective chart audit of patients presenting with a diagnosis of mechanical Low Back Pain to establish documented adherence to clinical guidelines. Stage 2 explored clinicians' perspectives towards factors influencing adherence to the guidelines via a study-specific survey and follow up focus groups. RESULTS: The audit demonstrated low adherence to the following guidelines: (i) appropriate prescription of analgesia, (ii) targeted education and advice, and (iii) attempts to mobilise. Three major themes were identified as factors influencing adherence to the guidelines: (1) clinician driven influences and factors, (2) workflow processes, and (3) patient expectations and behaviours. CONCLUSION: There was low adherence to some published guidelines and factors influencing adherence to the guidelines were multi-factorial. Understanding the factors that influence care decisions and developing strategies to address these can improve Emergency Department management of mechanical Low Back Pain.

Guiding ATR and PARP inhibitor combinationswith chemogenomic screens.

Combinations of ataxia telangiectasia- and Rad3-related kinase inhibitors (ATRis) and poly(ADP-ribose) polymerase inhibitors (PARPis) synergistically kill tumor cells through modulation of complementary DNA repair pathways, but their tolerability is limited by hematological toxicities. To address this, we performed a genome-wide CRISPR-Cas9 screen to identify genetic alterations that hypersensitize cells to a combination of the ATRi RP-3500 with PARPi, including deficiency in RNase H2, RAD51 paralog mutations, or the "alternative lengthening of telomeres" telomere maintenance mechanism. We show that RP-3500 and PARPi combinations kill cells carrying these genetic alterations at doses sub-therapeutic as single agents. We also demonstrate the mechanism of combination hypersensitivity in RNase H2-deficient cells, where we observe an irreversible replication catastrophe, allowing us to design a highly efficacious and tolerable in vivo dosing schedule. We present a comprehensive dataset to inform development of ATRi and PARPi combinations and an experimental framework applicable to other drug combination strategies.

CCNE1 amplification is synthetic lethal with PKMYT1 kinase inhibition.

Amplification of the CCNE1 locus on chromosome 19q12 is prevalent in multiple tumour types, particularly in high-grade serous ovarian cancer, uterine tumours and gastro-oesophageal cancers, where high cyclin E levels are associated with genome instability, whole-genome doubling and resistance to cytotoxic and targeted therapies1-4. To uncover therapeutic targets for tumours with CCNE1 amplification, we undertook genome-scale CRISPR-Cas9-based synthetic lethality screens in cellular models of CCNE1 amplification. Here we report that increasing CCNE1 dosage engenders a vulnerability to the inhibition of the PKMYT1 kinase, a negative regulator of CDK1. To inhibit PKMYT1, we developed RP-6306, an orally bioavailable and selective inhibitor that shows single-agent activity and durable tumour regressions when combined with gemcitabine in models of CCNE1 amplification. RP-6306 treatment causes unscheduled activation of CDK1 selectively in CCNE1-overexpressing cells, promoting early mitosis in cells undergoing DNA synthesis. CCNE1 overexpression disrupts CDK1 homeostasis at least in part through an early activation of the MMB-FOXM1 mitotic transcriptional program. We conclude that PKMYT1 inhibition is a promising therapeutic strategy for CCNE1-amplified cancers.

LSD1 is required for euchromatic origin firing and replication timing.

The chromatin-based rule governing the selection and activation of replication origins remains to be elucidated. It is believed that DNA replication initiates from open chromatin domains; thus, replication origins reside in open and active chromatin. However, we report here that lysine-specific demethylase 1 (LSD1), which biochemically catalyzes H3K4me1/2 demethylation favoring chromatin condensation, interacts with the DNA replication machinery in human cells. We find that LSD1 level peaks in early S phase, when it is required for DNA replication by facilitating origin firing in euchromatic regions. Indeed, euchromatic zones enriched in H3K4me2 are the preferred sites for the pre-replicative complex (pre-RC) binding. Remarkably, LSD1 deficiency leads to a genome-wide switch of replication from early to late. We show that LSD1-engaged DNA replication is mechanistically linked to the loading of TopBP1-Interacting Checkpoint and Replication Regulator (TICRR) onto the pre-RC and subsequent recruitment of CDC45 during origin firing. Together, these results reveal an unexpected role for LSD1 in euchromatic origin firing and replication timing, highlighting the importance of epigenetic regulation in the activation of replication origins. As selective inhibitors of LSD1 are being exploited as potential cancer therapeutics, our study supports the importance of leveraging an appropriate level of LSD1 to curb the side effects of anti-LSD1 therapy.

RP-3500: A Novel, Potent, and Selective ATR Inhibitor that is Effective in Preclinical Models as a Monotherapy and in Combination with PARP Inhibitors.

Ataxia telangiectasia and Rad3-related (ATR) kinase protects genome integrity during DNA replication. RP-3500 is a novel, orally bioavailable clinical-stage ATR kinase inhibitor (NCT04497116). RP-3500 is highly potent with IC50 values of 1.0 and 0.33 nmol/L in biochemical and cell-based assays, respectively. RP-3500 is highly selective for ATR with 30-fold selectivity over mammalian target of rapamycin (mTOR) and more than 2,000-fold selectivity over ataxia telangiectasia mutated (ATM), DNA-dependent protein kinase (DNA-PK), and phosphatidylinositol 3-kinase alpha (PI3Kα) kinases. In vivo, RP-3500 treatment results in potent single-agent efficacy and/or tumor regression in multiple xenograft models at minimum effective doses (MED) of 5 to 7 mg/kg once daily. Pharmacodynamic assessments validate target engagement, with dose-proportional tumor inhibition of phosphorylated checkpoint kinase 1 (pCHK1) (IC80 = 18.6 nmol/L) and induction of phosphorylated H2A.X variant histone (γH2AX), phosphorylated DNA-PK catalytic subunit (pDNA-PKcs), and phosphorylated KRAB-associated protein 1 (pKAP1). RP-3500 exposure at MED indicates that circulating free plasma levels above the in vivo tumor IC80 for 10 to 12 hours are sufficient for efficacy on a continuous schedule. However, short-duration intermittent (weekly 3 days on/4 days off) dosing schedules as monotherapy or given concomitantly with reduced doses of olaparib or niraparib, maximize tumor growth inhibition while minimizing the impact on red blood cell depletion, emphasizing the reversible nature of erythroid toxicity with RP-3500 and demonstrating superior efficacy compared with sequential treatment. These results provide a strong preclinical rationale to support ongoing clinical investigation of the novel ATR inhibitor, RP-3500, on an intermittent schedule as a monotherapy and in combination with PARP inhibitors as a potential means of maximizing clinical benefit.

Hepatic Abscess as Early Presentation of Perforated Diverticulitis.

A hepatic abscess is a rare condition which can have multiple etiologies, including biliary disease, intra-abdominal collections (appendicitis, diverticulitis, and inflammatory bowel disease), abdominal surgery, liver transplantation, and liver trauma. The diagnosis is primarily based on imaging findings of ultrasound and computed tomography scan. Management includes antibiotics and percutaneous drainage or surgical drainage of the abscess. Here, we present a case of a 43-year-old Hispanic female who initially presented with left lower quadrant and right upper quadrant abdominal pain for 1 week. She was found to have a hepatic abscess and pelvic abscess likely secondary to perforated diverticulum.

Isolation of Porcine Reproductive and Respiratory Syndrome Virus GP5-Specific, Neutralizing Monoclonal Antibodies From Hyperimmune Sows.

Porcine reproductive and respiratory syndrome (PRRS) is a devastating disease which impacts the pig industry worldwide. The disease is caused by PRRS viruses (PRRSV-1 and -2) which leads to abortions and other forms of reproductive failure in sows and severe respiratory disease in growing pigs. Current PRRSV vaccines provide limited protection; only providing complete protection against closely related strains. The development of improved PRRSV vaccines would benefit from an increased understanding of epitopes relevant to protection, including those recognized by antibodies which possess the ability to neutralize distantly related strains. In this work, a reverse vaccinology approach was taken; starting first with pigs known to have a broadly neutralizing antibody response and then investigating the responsible B cells/antibodies through the isolation of PRRSV neutralizing monoclonal antibodies (mAbs). PBMCs were harvested from pigs sequentially exposed to a modified-live PRRSV-2 vaccine as well as divergent PRRSV-2 field isolates. Memory B cells were immortalized and a total of 5 PRRSV-specific B-cell populations were isolated. All identified PRRSV-specific antibodies were found to be broadly binding to all PRRSV-2 isolates tested, but not PRRSV-1 isolates. Antibodies against GP5 protein, commonly thought to possess a dominant PRRSV neutralizing epitope, were found to be highly abundant, as four out of five B cells populations were GP5 specific. One of the GP5-specific mAbs was shown to be neutralizing but this was only observed against homologous and not heterologous PRRSV strains. Further investigation of these antibodies, and others, may lead to the elucidation of conserved neutralizing epitopes that can be exploited for improved vaccine design and lays the groundwork for the study of broadly neutralizing antibodies against other porcine pathogens.

Pasteurella multocida Bacteremia in an Immunocompromised Patient After Multiple Cat Scratches.

Pasteurella multocida (P. multocida) is a zoonotic organism found in the normal flora of domestic and wild animals. In this case report, we present a 70-year-old Caucasian male who presented with fever, chills, and greenish sputum which began hours prior to presentation. His symptoms were initially thought to be due to refractory pneumonia because the patient had been discharged from our hospital three weeks prior to presentation. Blood cultures grew P. multocida, a rare pathogen to cause bacteremia. He was treated with cefepime and later amoxicillin/clavulanic acid and made an uneventful recovery. Later history of the patient's cats scratching him was thought to be the mode of transmission. P. multocida infection is rare, and can also be dangerous and even fatal in immunocompromised individuals. Clinicians must therefore operate with a high degree of suspicion especially when treating immunocompromised patients with bacteremia.

The CIP2A-TOPBP1 axis safeguards chromosome stability and is a synthetic lethal target for BRCA-mutated cancer.

BRCA1/2-mutated cancer cells adapt to the genome instability caused by their deficiency in homologous recombination (HR). Identification of these adaptive mechanisms may provide therapeutic strategies to target tumors caused by the loss of these genes. In the present study, we report genome-scale CRISPR-Cas9 synthetic lethality screens in isogenic pairs of BRCA1- and BRCA2-deficient cells and identify CIP2A as an essential gene in BRCA1- and BRCA2-mutated cells. CIP2A is cytoplasmic in interphase but, in mitosis, accumulates at DNA lesions as part of a complex with TOPBP1, a multifunctional genome stability factor. Unlike PARP inhibition, CIP2A deficiency does not cause accumulation of replication-associated DNA lesions that require HR for their repair. In BRCA-deficient cells, the CIP2A-TOPBP1 complex prevents lethal mis-segregation of acentric chromosomes that arises from impaired DNA synthesis. Finally, physical disruption of the CIP2A-TOPBP1 complex is highly deleterious in BRCA-deficient tumors, indicating that CIP2A represents an attractive synthetic lethal therapeutic target for BRCA1- and BRCA2-mutated cancers.

Endogenous DNA 3' Blocks Are Vulnerabilities for BRCA1 and BRCA2 Deficiency and Are Reversed by the APE2 Nuclease.

The APEX2 gene encodes APE2, a nuclease related to APE1, the apurinic/apyrimidinic endonuclease acting in base excision repair. Loss of APE2 is lethal in cells with mutated BRCA1 or BRCA2, making APE2 a prime target for homologous recombination-defective cancers. However, because the function of APE2 in DNA repair is poorly understood, it is unclear why BRCA-deficient cells require APE2 for viability. Here we present the genetic interaction profiles of APE2, APE1, and TDP1 deficiency coupled to biochemical and structural dissection of APE2. We conclude that the main role of APE2 is to reverse blocked 3' DNA ends, problematic lesions that preclude DNA synthesis. Our work also suggests that TOP1 processing of genomic ribonucleotides is the main source of 3'-blocking lesions relevant to APEX2-BRCA1/2 synthetic lethality. The exquisite sensitivity of BRCA-deficient cells to 3' blocks indicates that they represent a tractable vulnerability in homologous recombination-deficient tumor cells.

Bilateral Pneumonia in a Patient with Chronic Bronchiectasis Caused by Achromobacter xylosoxidans Subspecies denitrificans.

Achromobacter xylosoxidans is a gram-negative bacillus that has a multitude of inherent and acquired antimicrobial resistance. It is a rare, isolated pathogen in patients without cystic fibrosis (CF). We report the case of a 76-year-old Caucasian male with a history of chronic obstructive pulmonary disease (COPD), previous Mycobacterium-avium intracellulare (MAI) infection, and chronic bronchiectasis who did not respond to three courses of outpatient antibiotics for a chronic cough. He also had a 21-lb weight loss. The diagnosis of Achromobacter xylosoxidans subspecies denitrificans was made through bronchoscopy with bronchoalveolar lavage (BAL). There are few case reports describing Achromobacter xylosoxidans subspecies denitrificans in non-CF patients. Achromobacter xylosoxidans colonization might be linked to predisposing lung damage such as in CF and bronchiectasis. The bacterium is frequently multidrug-resistant. More studies are needed to develop recommendations for clinical guidelines to address the increasing antibiotic resistance to Achromobacter xylosoxidans.

Establishment of Systems to Enable Isolation of Porcine Monoclonal Antibodies Broadly Neutralizing the Porcine Reproductive and Respiratory Syndrome Virus.

The rapid evolution of porcine reproductive and respiratory syndrome viruses (PRRSV) poses a major challenge to effective disease control since available vaccines show variable efficacy against divergent strains. Knowledge of the antigenic targets of virus-neutralizing antibodies that confer protection against heterologous PRRSV strains would be a catalyst for the development of next-generation vaccines. Key to discovering these epitopes is the isolation of neutralizing monoclonal antibodies (mAbs) from immune pigs. To address this need, we sought to establish systems to enable the isolation of PRRSV neutralizing porcine mAbs. We experimentally produced a cohort of immune pigs by sequential challenge infection with four heterologous PRRSV strains spanning PRRSV-1 subtypes and PRRSV species. Whilst priming with PRRSV-1 subtype 1 did not confer full protection against a subsequent infection with a PRRSV-1 subtype 3 strain, animals were protected against a subsequent PRRSV-2 infection. The infection protocol resulted in high serum neutralizing antibody titers against PRRSV-1 Olot/91 and significant neutralization of heterologous PRRSV-1/-2 strains. Enriched memory B cells isolated at the termination of the study were genetically programmed by transduction with a retroviral vector expressing the Bcl-6 transcription factor and the anti-apoptotic Bcl-xL protein, a technology we demonstrated efficiently converts porcine memory B cells into proliferating antibody-secreting cells. Pools of transduced memory B cells were cultured and supernatants containing PRRSV-specific antibodies identified by flow cytometric staining of infected MARC-145 cells and in vitro neutralization of PRRSV-1. Collectively, these data suggest that this experimental system may be further exploited to produce a panel of PRRSV-specific mAbs, which will contribute both to our understanding of the antibody response to PRRSV and allow epitopes to be resolved that may ultimately guide the design of immunogens to induce cross-protective immunity.

Low-calorie sweetener use, weight, and metabolic health among children: A mini-review.

A reduction in the consumption of added sugars and sugar-sweetened beverages (SSBs) is a key focus of public health recommendations for a healthy diet among children. One approach to lower added sugar intake is to instead use low-calorie sweeteners (LCSs), which contain no or few calories. Consumption of LCSs is increasing worldwide, with the most marked rise observed among children and adolescents. However, the extent to which LCS consumption is helpful or harmful for weight management is controversial, particularly when LCS consumption begins in childhood. Herein, we summarize the limited existing literature examining effects of paediatric LCS consumption on appetite, energy intake, and body weight. While positive associations between LCS consumption and weight gain are reported in observational analyses, the majority of intervention studies, some of which blinded children to the contents of the drinks, report benefits of LCSs for reducing excessive child weight gain. Several potential mechanisms have been proposed to explain LCS effects on body weight, including LCS-induced promotion of appetite and energy intake. Yet studies assessing effects of beverages with LCSs (LCSBs) compared with SSBs on child appetite report mixed findings. Some demonstrate that children completely compensate for the diluted energy content of LCSBs by eating more solid food calories at subsequent meals compared with children administered SSBs, while others report a reduction in total energy intake with LCSB ingestion. Given the limited studies and resulting uncertainty as to whether LCSs benefit or worsen weight and metabolic health in children is integral that effects of LCS use during childhood continue to be investigated in future prospective studies.

Carbon dioxide addition to coral reef waters suppresses net community calcification.

Coral reefs feed millions of people worldwide, provide coastal protection and generate billions of dollars annually in tourism revenue. The underlying architecture of a reef is a biogenic carbonate structure that accretes over many years of active biomineralization by calcifying organisms, including corals and algae. Ocean acidification poses a chronic threat to coral reefs by reducing the saturation state of the aragonite mineral of which coral skeletons are primarily composed, and lowering the concentration of carbonate ions required to maintain the carbonate reef. Reduced calcification, coupled with increased bioerosion and dissolution, may drive reefs into a state of net loss this century. Our ability to predict changes in ecosystem function and associated services ultimately hinges on our understanding of community- and ecosystem-scale responses. Past research has primarily focused on the responses of individual species rather than evaluating more complex, community-level responses. Here we use an in situ carbon dioxide enrichment experiment to quantify the net calcification response of a coral reef flat to acidification. We present an estimate of community-scale calcification sensitivity to ocean acidification that is, to our knowledge, the first to be based on a controlled experiment in the natural environment. This estimate provides evidence that near-future reductions in the aragonite saturation state will compromise the ecosystem function of coral reefs.

HELB Is a Feedback Inhibitor of DNA End Resection.

DNA double-strand break repair by homologous recombination is initiated by the formation of 3' single-stranded DNA (ssDNA) overhangs by a process termed end resection. Although much focus has been given to the decision to initiate resection, little is known of the mechanisms that regulate the ongoing formation of ssDNA tails. Here we report that DNA helicase B (HELB) underpins a feedback inhibition mechanism that curtails resection. HELB is recruited to ssDNA by interacting with RPA and uses its 5'-3' ssDNA translocase activity to inhibit EXO1 and BLM-DNA2, the nucleases catalyzing resection. HELB acts independently of 53BP1 and is exported from the nucleus as cells approach S phase, concomitant with the upregulation of resection. Consistent with its role as a resection antagonist, loss of HELB results in PARP inhibitor resistance in BRCA1-deficient tumor cells. We conclude that mammalian DNA end resection triggers its own inhibition via the recruitment of HELB.

Deepwater Horizon oil in Gulf of Mexico waters after 2 years: transformation into the dissolved organic matter pool.

Recent work has shown the presence of anomalous dissolved organic matter (DOM), with high optical yields, in deep waters 15 months after the Deepwater Horizon (DWH) oil spill in the Gulf of Mexico (GOM). Here, we continue to use the fluorescence excitation-emission matrix (EEM) technique coupled with parallel factor analysis (PARAFAC) modeling, measurements of bulk organic carbon, dissolved inorganic carbon (DIC), oil indices, and other optical properties to examine the chemical evolution and transformation of oil components derived from the DWH in the water column of the GOM. Seawater samples were collected from the GOM during July 2012, 2 years after the oil spill. This study shows that, while dissolved organic carbon (DOC) values have decreased since just after the DWH spill, they remain higher at some stations than typical deep-water values for the GOM. Moreover, we continue to observe fluorescent DOM components in deep waters, similar to those of degraded oil observed in lab and field experiments, which suggest that oil-related fluorescence signatures, as part of the DOM pool, have persisted for 2 years in the deep waters. This supports the notion that some oil-derived chromophoric dissolved organic matter (CDOM) components could still be identified in deep waters after 2 years of degradation, which is further supported by the lower DIC and partial pressure of carbon dioxide (pCO2) associated with greater amounts of these oil-derived components in deep waters, assuming microbial activity on DOM in the current water masses is only the controlling factor of DIC and pCO2 concentrations.

A negative genetic interaction map in isogenic cancer cell lines reveals cancer cell vulnerabilities.

Improved efforts are necessary to define the functional product of cancer mutations currently being revealed through large-scale sequencing efforts. Using genome-scale pooled shRNA screening technology, we mapped negative genetic interactions across a set of isogenic cancer cell lines and confirmed hundreds of these interactions in orthogonal co-culture competition assays to generate a high-confidence genetic interaction network of differentially essential or differential essentiality (DiE) genes. The network uncovered examples of conserved genetic interactions, densely connected functional modules derived from comparative genomics with model systems data, functions for uncharacterized genes in the human genome and targetable vulnerabilities. Finally, we demonstrate a general applicability of DiE gene signatures in determining genetic dependencies of other non-isogenic cancer cell lines. For example, the PTEN(-/-) DiE genes reveal a signature that can preferentially classify PTEN-dependent genotypes across a series of non-isogenic cell lines derived from the breast, pancreas and ovarian cancers. Our reference network suggests that many cancer vulnerabilities remain to be discovered through systematic derivation of a network of differentially essential genes in an isogenic cancer cell model.