Increased neutrophil infiltration and lower prevalence of tumor mutation burden and microsatellite instability are hallmarks of RAS mutant colorectal cancers

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Background: The tumor microenvironment (TME) of colorectal cancers (CRC) is modulated by oncogenic drivers such as KRAS. The TME comprises a broad landscape of immune infiltration. How tumor genomics associates with the immune cell landscape is less known. We aim to characterize immune cell types in RAS wild-type (WT) and mutant (MT) CRC, and to examine the prevalence of immuno-oncologic (IO) biomarkers (e.g. tumor mutation burden (TMB), PD-L1, MSI-H/dMMR) in these tumors. We performed genomic and transcriptomic analysis to confirm associations of mutant RAS with immune infiltration of the TME conducive to metastasis vs. potential response to immunotherapies. Methods: A total of 7,801 CRC were analyzed using next-generation sequencing on DNA (NextSeq, 592 Genes and WES, NovaSEQ), RNA (NovaSeq, whole transcriptome equencing) and IHC (Caris Life Sciences, Phoenix, AZ). MSI/MMR was tested by FA, IHC and NGS. TMB-H was based on a cut-off of > 10 mutations per MB). Immune cell fraction was calculated by QuantiSeq (Finotello 2019, Genome Medicine). Significance was determined by X2 and Fisher-Exact and p adjusted for multiple comparisons (q) was <0.05. Results: Mutant KRAS was seen in 48% of mCRC tumors; NRAS in 3.7%, HRAS in 0.1%. The distribution was similar in patients < or >= than 50 yrs. In MSS tumors, there was a significantly higher neutrophil infiltration in KRAS MT (median cell fraction 6.6% vs. 5.9%) and NRAS MT (6.9%) overall and also when individual codons were studied. B cells, M2 macrophages, CD8+ T cells, dendritic cells and fibroblasts were lower in KRAS mutant tumors; B cells and M1 macrophages are lower in NRAS (q<0.05). dMMR/MSI-H was significantly more prevalent in RAS WT (9.1%) than in KRAS (2.9%) or NRAS MT (1.8%) tumors, and highest in HRAS MT tumors (60%, q<0.05).TMB-H was more prevalent in RAS WT (11%) than KRAS (5.8%) or NRAS (5.1%) MT, and highest in HRAS MT tumors (70%, all q<0.05). In MSS tumors, KRAS MT tumors showed more TMB-H than WT (3.1% vs. 2.1%, q<0.05), especially in KRAS non 12/13/61 mutations (5.5%, vs. 2.1%, q<0.05) and G12C (4.4%, p<0.05). PD-L1 expression was studied: in MSS tumors, KRAS-G12D (10.4%) and G13 MT (11.8%) showed higher mutation rates than RAS WT tumors (q<0.05). Conclusions: KRAS & NRAS mutations are associated with increased neutrophil abundance, with codon specific differences, while HRAS shows no difference. Overall CD8+ T cells and B cells are less abundant in KRAS & NRAS mutants; substantial variability was seen amongst different protein changes. RAS mutations were more prevalent overall than generally reported, but did not vary by age. These results demonstrate significant differences in the TME of RAS mutant CRC that identify variable susceptibilities to immuno-oncologic agents, and provide further detailed characterization of heterogeneity between RAS variants, at the molecular as well as immunogenic levels.

Clinical features and outcomes of colloid carcinoma of pancreas compared to pancreatic ductal adenocarcinoma

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Background: Colloid carcinoma (CC) of the pancreas is a rare histopathological subtype of ductal adenocarcinoma (PDAC), with poorly defined prognostic factors and therapeutic outcomes. The aim of this study is to characterize the clinicopathological features and evaluate the overall survival (OS) and prognostic factors of patients with pancreatic CC using National Cancer Database (NCDB). Methods: Patients diagnosed with CC of the pancreas and PDAC between 2004 and 2016 were identified from the NCDB using ICD-O-3 morphology (8480/3 for CC and 8140/3 for PDAC) and topography codes (C25). Univariate and multivariable analyses were conducted and Kaplan-Meier analysis and Cox proportional hazards models were used to perform OS analysis. Results: A total of 56,846 patients met the inclusion criteria for the final analysis. Of the total population included, 2,430 patients (4.3%) had CC and 54,416 patients (95.7%) had PDAC. For both, CC and PDAC, there was a male preponderance (52.0%, 52.5%), Caucasians (85.1%, 84%), occurrence above the age of 70 (39.2%, 38.2%), and the most common primary site was the head of the pancreas (50.5%, 53%). For CC, the percentage of pathologic stage III colloid pancreas cancer appeared the lowest (3.5%, 85 patients), compared to stage I (16.7%), stage II (37.8%), and stage IV (42.1%). While in PDAC, the percentage of pathologic stage I (5.94%) and stage III (4.44%) patients was lower than stage II (37.21%) and IV (52.41%). CC and PDAC more frequently presented with < 5cm tumor, at academic or research cancer centers, and diagnosed between 2009 and 2013 compared to 2004–2008 ( p< 0.001). For both CC and PDAC, the majority underwent surgical resection (58%, 53%), systemic chemotherapy (57.8%, 63%) and did not receive radiotherapy (78.8%, 77.6%). A positive surgical margin on pathologic evaluation was associated with worse outcomes for CC and PDAC in both univariate and multivariate analysis (HR 1.61; 1.56–1.66; p< 0.001 and HR 1.43; 1.38–1.48, p< 0.001). CC had a better 1-year overall survival (OS) in all stages compared to PDAC (p < 0.001). In multivariate analysis, mucinous carcinoma histology, female sex, diagnosis between 2004 and 2009, well/moderately differentiated histology, chemotherapy, age at diagnosis less than 60, radiation therapy after surgery, and local surgical procedure of primary site and pancreatectomy (p < 0.001) were associated with better OS compared to PDAC. Colloid histology was associated with better 1-year overall survival (OS) in all stages compared to PDAC (p < 0.001). Conclusions: Colloid carcinoma of pancreas is associated with a better overall survival as compared to pancreatic ductal adenocarcinoma. This is the largest study to address the clinical features and outcomes of colloid carcinoma of pancreas.

Treatment outcomes for stage T1b-2 esophagogastric adenocarcinomas

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Background: Treatment of localized esophageal, gastroesophageal junction (GEJ), and stomach cancer is neoadjuvant therapy with either chemoradiation or chemotherapy followed by surgery. Treatment for T1b-2 stage disease is not well evaluated and this stage is underrepresented in prospective studies. The aim of this study is to evaluate survival outcomes among the three treatment modalities (neoadjuvant chemotherapy (NACT), neoadjuvant chemoradiation (NACRT), and upfront surgery (US)) in this population using the National Cancer Database (NCDB). Methods: Patients (pts) with clinical stage T1b-2N0 and any pathological stage (excluding metastatic) adenocarcinoma of the esophagus, GEJ, and stomach treated with neoadjuvant therapy or upfront surgery, with or without adjuvant chemotherapy (AC), were identified between 2004 and 2015 in the NCDB. Univariate and multivariable analyses were conducted, and Kaplan-Meier analysis and Cox proportional hazard models were used to identify the association between the three treatment modalities and overall survival (OS). Results: A total of 2260 pts were analyzed. The median follow-up was 66.6 months. The median age was 67 years. Most pts were White (86%) and male (77%). 1018 (45%) had moderately-differentiated grade, while 946 (42%) had poorly-differentiated/undifferentiated grade. The most common site of disease was the lower third of esophagus (34.1%). 161 pts (7%) received NACT, of whom 45 pts received AC; 537 pts (24%) received NACRT, of whom 40 pts received AC. 1562 pts (69%) underwent US, of whom 146 pts received AC. US with AC was associated with the best survival, followed by NACT with AC; median OS was 90.1 and 86.8 months for surgery with AC and NACT with AC, respectively. NACRT was associated with the worst survival (39.5 and 40.2 months with and without AC, respectively). The 5-year OS rates were 59.8%, 58.5%, 52.1%, 44.9%, 37.3%, and 37.8%, for US, NACT, and NACRT, with and without AC, respectively. The rate of tumor upstaging was highest in the NACT group, followed by the NACRT group, and lowest in the US group. Postsurgically, 62 (39%) and 48 (30%) pts in the NACT group and 198 (37%) and 161 (30%) pts in the NACRT group had upstaging in their T and N stages, respectively, compared to 214 (13%) and 326 (21%) pts in the US group. For the 1107 pts who also had pathological T1b-2N0 stage disease following US, no difference in survival was observed with or without AC. Conclusions: Upfront surgery with adjuvant chemotherapy and perioperative chemotherapy are associated with the best survival compared to preoperative radiotherapy. This is the largest study to address the best approach for the treatment of T1b-2 stage disease.

Using the Theoretical Domains Framework to investigate clinicians’ behavioural determinants of antimicrobial prescribing in Qatar

Introduction

A recent systematic review by Talkhan et al demonstrated the need for theoretically based behaviour change interventions in this area. [1] For development of such complex interventions, emphasis should be placed on using theory to systematically identify behavioural determinants of antimicrobial prescribing.

Aim

To identify and quantify clinicians’ behavioural determinants of antimicrobial prescribing in Qatar.

Methods

This cross-sectional survey is part of a multi-phase explanatory, sequential mixed methods PhD project in Qatar. Questionnaires were distributed (online and paper based) to all doctors (~4,000) and pharmacists (~400) within Hamad Medical Corporation (HMC, the main healthcare provider). The questionnaire was developed with reference to the Determinants of Implementation Behaviour Questionnaire (a generic questionnaire derived from the 14 theoretical domains of the Theoretical Domains Framework, TDF). [2] Each item was presented as a 5-point Likert scale (scored 5=Strongly agree to 1=Strongly disagree). Personal and practice demographics were also collected for data contextualisation. The draft questionnaire was reviewed for face/content validity by an expert panel of six researchers in Qatar and the UK with experience in the use of the TDF, followed by ‘Think aloud’ testing and piloting. Analysis investigated the behavioural determinants and influential factors through descriptive, principal component analysis (PCA) and inferential analysis. Ethics approval was granted from a UK university and HMC.

Results

In total, 535 responses were received, 339 (63.4%) from doctors and 196 (36.6%) from pharmacists. Respondents were predominantly male, 346 (64.7%). Just over half (n=285, 53.3%) had ≤ 5 years’ experience as health professionals. PCA showed a three component (C) solution with components incorporating a number of questionnaire items labelled: ‘Guidelines compliance’ (C1 with 8 items), ‘Influences on prescribing’ (C2 with 7 items) and ‘Self-efficacy’ (C3 with 5 items) in prescribing/recommendation activity. A scale score for each respondent was calculated through summation of Likert scores for the relevant questionnaire items within each component. These scales had high internal reliability (Cronbach’s alpha all &gt;0.7) showing consistency in response between component items indicating statistical appropriateness for developing scales. The median score (possible scale range, midpoint) for each scale was C1, 32 (8 to 40, 24), C2, 26 (7 to 35, 21) and C3, 20, (5 to 25, 15). By way of example Table 1 shows levels of agreement for items in C2. This shows lower levels of agreement than C1 scale with the median scale score (26) closer to the midpoint (21) indicating that respondents had less positive views. Inferential analysis using these scale scores and free text analysis is in progress.

Conclusion

A theoretical basis was used throughout providing insights to behavioural determinants for the development of a theory-based behaviour change intervention. Preliminary results suggest that social influences, staff development and quality monitoring may be useful targets for behaviour change interventions to improve antimicrobial prescribing practice. Limitations include potential social desirability bias and focus on one healthcare organisation/country in the Middle East which may limit generalisability of findings. More in-depth exploration is required to select and test appropriate linked theory-based behaviour change techniques.

References

1. Talkhan H, Stewart D, McIntosh T, Ziglam H Palli Valapila, A; Moza Sulaiman H, Diab M, Cunningham S. The use of theory in the development and evalu​ation of behaviour change interventions to improve antimicrobial prescribing: a systematic review. J Antimicrob Chemother. 2020;75(9):2394–2410, Available from https://doi.org/10.1093/jac/dkaa154 [Accessed 12 Oct 2020].

2. Huijg JM, Gebhardt WA, Dusseldorp E, Verheijden MW, van der Zouwe N, Middelkoop BJ, Crone MR. Measuring determinants of implementation behaviour: psychometric properties of a questionnaire based on the Theoretical Domains Framework. Implement. Sci. 2014;9(1):33.

Survival outcomes of adjuvant chemotherapy in elderly patients with stage III colon cancer

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Background: The survival impact of multi-agent (MAC) as compared to single-agent (SAC) adjuvant chemotherapy (AC) in elderly patients with stage III colon cancer (CC) remains controversial. The aim of this study is to evaluate the survival outcome comparing MAC to SAC in this population utilizing the National Cancer DataBase (NCDB). Methods: Patients 70 years and older with pathological stage III CC were identified between 2004 and 2015 from the NCDB using ICD-O-3 morphology and topography codes: 8140-47, 8210-11, 8220-21, 8260-63, 8480-81, 8490, and C18.0-18.8 (without C18.1). Univariate and multivariable analyses were conducted and Kaplan-Meier analysis and Cox proportional hazard models were used to identify the association between MAC vs. SAC and overall survival (OS). Results: A total of 41,707 elderly patients (≥70 years old) with stage III CC were identified. Around half of the patients (n = 20,257; 48.5%) received AC; the majority of whom (n = 12,923, 63.8%) received MAC. The median age was 79 (range 70-90). Of the patients who received AC, the majority were female (n = 11,201, 55.3 %), Caucasians (87.4%) and had a moderately differentiated tumor grade (n = 12,619, 62.3%). Tumor size more than 4 cm was identified in 11,785 (58.2%) patients and 18,496 (91.3%) had negative surgical margins. Low-risk stage III CC constituted 50.6% (n = 10,264) of the study population. High-risk stage III CC was associated with worse OS compared to low-risk disease (p < 0.001). MAC was associated with better 5-year OS compared to SAC (p < 0.001). High-risk stage III patients who received MAC had an OS of 4.2 v. 3.4 years in SAC (p < 0.001). In low risk stage III, patients who received MAC had median OS of 8.5 v. 7 years in SAC (p < 0.001). In Univariate, male sex, positive surgical margin, insurance and facility types, age, year of diagnosistumor size, and Charlson-Deyo Score of > 2 were associated with worse OS (p < 0.05). Conclusions: Multi-agent AC is associated with better survival in stage III CC patients 70 years and older compared to SAC. Enhanced benefit of MAC was shown for both low risk and high risk stage III CC.

Phase II trial of nivolumab and metformin in patients with treatment refractory microsatellite stable metastatic colorectal cancer

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Background: Preclinical data suggests metformin can improve immune exhaustion of tumor infiltrating lymphocytes and potentiate the effects of PD-1 blockade. By normalizing the hypoxic TME, metformin was shown to improve cytotoxic T cell function and efficacy of anti-PD-1 antibody in highly aggressive B16 melanoma and MC38 colon adenocarcinoma tumor models. Based on this preclinical rationale we conducted a phase II study with nivolumab and metformin combination in treatment refractory MSS metastatic colorectal cancer (mCRC). Methods: Nivolumab 480 mg IV every 4 weeks and Metformin 1000 mg po twice daily was administered in 28-day cycles following a 14-day metformin only lead-in phase.Eligible patients included stage IV metastatic treatment refractory MSS mCRC (patients must have received oxaliplatin, irinotecan, and fluoropyrimidine), age ≥18 years, ECOG PS 0-1, adequate organ function, no prior anti PD-1 agent. The primary endpoint was overall response rate (ORR). Secondary endpoints included overall survival (OS) and progression free survival (PFS). Simon’s two-stage Minimax design was employed (H0: ORR =4%; H1: ORR=15%; alpha = 0.1; power =80%). If ≥1 objective response was observed in the first evaluable 18 patients, 10 additional patients would be included in the cohort. ≥3 objective responders in 28 patients would be required to be considered positive study. Pre-treatment and on-treatment research biopsies and correlative peripheral blood specimens were collected. Results: A total of 24 patients were enrolled, 6 patients were replaced per protocol, and 18 patients had evaluable disease. Of the 18 evaluable patients 11/18 (61%) were female, median age 58 [IQR 50-67]. 2 patients had prolonged stable disease (4 and 10 cycles). No patients had objective response based on RECIST 1.1. Median OS and PFS was 5.1 months [95% CI (2-11.7)] and 2.3 months [95% CI (1.7-2.4)], respectively. Most common grade 3 and 4 toxicities were anemia (n=2) and diarrhea (n=2). Conclusions: In treatment refractory MSS mCRCnivolumab and metformin combination was well tolerated. Two patients achieved stable disease, but no objective response was seen; therefore, the study did not proceed with the second stage of enrollment. Immunologic correlative analysis of this study is ongoing. Clinical trial information: NCT03800602.

Impact of primary tumor size/horizontal extent on survival in colorectal cancer

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Background: Pathologic staging in colorectal cancer (CRC) is crucial in patient management. Data regarding the impact of size/horizontal tumor extent is limited, contradictory and currently excluded from the American Joint Committee on Cancer (AJCC) staging model. However, a previously published SEER analysis showed that AJCC stages I and IIIA have similar 2- and 5- year survival rates, and worse rates for stage II. Using the largest cohort to date, we report the impact of primary tumor size on CRC survival. Methods: Data were obtained from all US hospitals that contributed to the National Cancer Database (NCDB) between 2010 and 2015. Univariate and multivariate analyses were performed to identify factors associated with patient outcome. Kaplan-Meier analysis and Cox proportional hazards models were used to assess the association between tumor/patient characteristics and overall survival (OS). Results: A total of 61,145 patients were identified with a similar gender distribution (M/F:50.9%/49.1%). The mean age was 62.7years (SD+/-14.1) and 82% were non-Hispanic Whites. Majority had colon primary (82.7%) and 82.4% had microsatellite stable (MSS) disease. Distribution across stages I-IV was 20.1%, 32.1%, 34.7% and 13.2% respectively. Among the total study population, AJCC stage correlated closely with OS on multivariate analysis (HR 1.49, 2.29, 8.38 for stages II to IV compared to stage I), while the distinguishing power for tumor size was relatively mild (HR 1.19 and 1.33 for 5-10 cm and >5cm compared to <5cm). Among patients with stage II disease, tumors >10cm were associated with worse survival compared to those <5cm (HR 1.2; 1.03-1.39; p=0.22). Stage III disease also had differential survival rates; patients with tumors 5-10cm (HR 1.21; 1.14-1.28; p<0.001) and >10cm (HR 1.57; 1.37-1.80; p<0.001) had worse survival than those <5cm. Patients with stage II who did not receive adjuvant chemotherapy (CTX) had worse survival outcomes (HR 1.29; 1.08-1.55; p=0.005) compared to stage III disease who did. Accounting for tumor size, there was no statistically significant survival differences between stage I patients and stages II and III patients who received adjuvant chemotherapy. Conclusions: Tumors larger than 10cm have inferior outcomes among patients in the same AJCC stages. Stage II patients without adjuvant CTX did worse than stage III with CTX. Further studies are needed to clarify the role of tumor size in staging models. [Table: see text]

Pancreatic adenocarcinoma: molecular drivers and the role of targeted therapy

Prognosis from pancreatic ductal adenocarcinoma (PDAC) continues to be poor despite the many efforts channeled to improve its management. Although the mainstay treatment is still traditional chemotherapy, recent advances highlighted a promising potential for targeted therapy in the management of this disease. Those advances emphasize the significance of timely genomic profiling of tumor tissue as well as germline testing of patients to identify potential markers of targeted therapy. While targeted therapy is reserved for a relatively small subset of patients with PDAC, ongoing research is uncovering additional markers, and targeted agents, that will hopefully translate to better outcomes for patients.

Gastric cancer: a comprehensive review of current and future treatment strategies

Gastric cancer remains a major unmet clinical problem with over 1 million new cases worldwide. It is the fourth most commonly occurring cancer in men and the seventh most commonly occurring cancer in women. A major fraction of gastric cancer has been linked to variety of pathogenic infections including but not limited to Helicobacter pylori (H. pylori) or Epstein Barr virus (EBV). Strategies are being pursued to prevent gastric cancer development such as H. pylori eradication, which has helped to prevent significant proportion of gastric cancer. Today, treatments have helped to manage this disease and the 5-year survival for stage IA and IB tumors treated with surgery are between 60 and 80%. However, patients with stage III tumors undergoing surgery have a dismal 5-year survival rate between 18 and 50% depending on the dataset. These figures indicate the need for more effective molecularly driven treatment strategies. This review discusses the molecular profile of gastric tumors, the success, and challenges with available therapeutic targets along with newer biomarkers and emerging targets.

Gastric Cancer Heterogeneity and Clinical Outcomes

Gastric adenocarcinoma is a highly aggressive disease with poor overall survival. The aggressive nature of this disease is in part due to the high intra and inter tumoral heterogeneity and also due to the late diagnosis at presentation. Once progression occurs, treatment is more difficult due to the adaptation of tumors, which acquires resistance to commonly used chemotherapeutics. In this report, using publicly available data sets and pathway analysis, we highlight the vast heterogeneity of gastric cancer by investigating genes found to be significantly perturbed. We found several upregulated genes in the diffuse gastric cancer subtypes share similarity to gastric cancer as a whole which can be explained by the increase in this subtype of gastric cancer throughout the world. We report significant downregulation of genes that are underrepresented within the literature, such as ADH7, GCNT2, and LIF1, while other genes have not been explored within gastric cancer to the best of our knowledge such as METTL7A, MAL, CWD43, and SLC2A12. We identified gender to be another heterogeneous component of this disease and suggested targeted treatment strategies specific to this heterogeneity. In this study, we provide an in-depth exploration of the molecular landscape of gastric cancer in order to shed light onto novel areas of gastric cancer research and explore potential new therapeutic targets.

Pharmacotherapeutic strategies for treating pancreatic cancer: advances and challenges

INTRODUCTION

Despite many efforts to improve the outcome of pancreatic ductal adenocarcinoma (PDAC), its prognosis remains poor, which is mostly related to late diagnosis and drug resistance. Improving systemic therapy is considered the major challenge in improving the outcome of this disease.

AREAS COVERED

This review covers novel chemotherapy and targeted agents in the treatment of PDAC, with a focus on advanced stage disease.

EXPERT OPINION

Current frontline therapies used in the treatment of patients with PDAC with favorable performance status are gemcitabine (GEM) and nab-paclitaxel or 5-fluorouracil, leucovorin, irinotecan, and oxaliplatin (FOLFIRINOX). PDAC has a number of genetic mutations that may explain its biological behavior, such as KRAS, p53 and CDK2NA, which occur in more than 90% of cases. Unfortunately, to this day, a specific targeting agent to any of those frequent gene mutations is lacking. Emerging areas of targeted therapies include the DNA repair, stroma, metabolism, and stem cells. Immunotherapy with either vaccines or immune checkpoint inhibitors has not produced any significant improvements in outcome of PDAC. Incorporating different approaches in therapy, including conventional, immunological, and others, is key in offering patients with the best possible care.

S. aureus endocarditis: Clinical aspects and experimental approaches

Infective endocarditis (IE) is a life-threatening disease, caused by septic vegetations and inflammatory foci on the surface of the endothelium and the valves. Due to its complex and often indecisive presentation the mortality rate is still about 30%. Most frequently bacterial microorganisms entering the bloodstream are the underlying origin of the intracardiac infection. While the disease was primarily restricted to younger patients suffering from rheumatic heart streptococci infections, new at risk categories for Staphylococcus (S.) aureus infections arose over the last years. Rising patient age, increasing drug resistance, intensive treatment conditions such as renal hemodialysis, immunosuppression and long term indwelling central venous catheters but also the application of modern cardiac device implants and valve prosthesis have led to emerging incidences of S. aureus IE in health care settings and community. The aetiologic change has impact on the pathophysiology of IE, the clinical presentation and the overall patient management. Despite intensive research on appropriate in vitro and in vivo models of IE and gained knowledge about the fundamental mechanisms in the formation of bacterial vegetations and extracardiac complications, improved understanding of relevant bacterial virulence factors and triggered host immune responses is required to help developing novel antipathogenic treatment strategies and pathogen specific diagnostic markers. In this review, we summarize and discuss the two main areas affected by the changing patient demographics and provide first, recent knowledge about the pathogenic strategies of S. aureus in the induction of IE, including available experimental models of IE used to study host-pathogen interactions and diagnostic and therapeutic targets. In a second focus we present diagnostic (imaging) regimens for patients with S. aureus IE according to current guidelines as well as treatment strategies and surgical recommendations.