Cardiac surgery in the heart transplant recipient: Outcome analysis and long-term results

BACKGROUND

Survival rates following cardiac transplantation continue to improve. Due to the scarcity of available organs, extended donor criteria have become more prevalent in clinical practice. In this context, the risk of developing cardiac pathology requiring surgical correction is increasing.

METHODS

Between January 1991 and October 2010, a total of 479 patients received cardiac transplantations at the University Hospital Heidelberg. Of those, 18 (3.8%) patients required subsequent cardiac surgery until 2018. Short- and long-term analyses were performed.

RESULTS

Indications for cardiac surgery included valvular disease (n = 16) with the majority of cases affecting the tricuspid valve (n = 10), while 6 patients received mitral valve surgery, of whom 3 patients underwent concomitant valve surgery. Other indications included CABG (n = 1) and re-transplantation (n = 1) for allograft dysfunction. Mean follow-up time was 6.5 years, while mean interval to surgery was 6.0 years. Early mortality was 11.1% (n = 2), while overall survival at 1, 5, and 10 years were, 88.1%, 81.4%, and 52.2%, respectively. Compared to an overall survival of that transplant cohort at 1, 5, and 10 years of 76.7%, 66.7%, and 52.4% percent, respectively (P = .271).

CONCLUSION

According to our data, redo cardiac surgery can be performed with acceptable mortality and morbidity. Atrioventricular valve pathology plays a chief role in these patients.

Imaging-Based 4D Aortic Pressure Mapping in Marfan Syndrome Patients: A Matched Case-Control Study

BACKGROUND

Marfan syndrome predisposes to aortic aneurysm, dissection, and rupture. We sought to investigate aortic 4-dimensional (4D) relative pressure maps derived from 4D flow cardiovascular magnetic resonance to identify disease characteristic alterations of the intraaortic pressure field in Marfan patients with aortic root dilation compared with age- and sex-matched healthy controls.

METHODS

This prospective case-control study included 11 Marfan patients with aortic root dilation (31 ± 5 years, 5 female) and 11 age- and sex-matched healthy controls (31 ± 8 years, 5 female) undergoing 4D flow cardiovascular magnetic resonance of the thoracic aorta. 4D relative pressure maps were computed and compared between groups for 8 aortic regions.

RESULTS

Aortic root diameters were significantly larger in patients compared with controls (43 vs 31 mm, P < .001), but not in the proximal descending aorta (23 vs 21 mm, P = .19). Regional pressure gradients over the cardiac cycle were significantly altered in Marfan patients with significantly higher minimum pressure gradients in the proximal ascending aorta (-44.3 vs -97.0 mm Hg/m, P < .001) and significantly lower maximum pressure gradients in the proximal descending aorta (55.1 vs 82.3 mm Hg/m, P < .01). The latter finding was associated with pathologic vortical flow patterns. Regional pressure gradient at mid systole significantly correlated with aortic diameter (proximal ascending aorta: r = 0.73, P < .001; proximal descending aorta: r = -0.59, P = .004).

CONCLUSIONS

Noninvasive 4D pressure mapping derived from 4D flow cardiovascular magnetic resonance revealed significant alterations of spatiotemporal pressure characteristics in the thoracic aorta of Marfan patients. These alterations were most pronounced in the proximal ascending aorta and the proximal descending aorta, corresponding to the regions where aortic dissections often originate in Marfan patients.

The reimplantation valve-sparing aortic root replacement technique for patients with Marfan syndrome: A single-center experience

Valve-sparing aortic root replacement (VSARR) through reimplantation technique is widely regarded as optimal surgical approach for Marfan syndrome (MFS) patients. Perioperative and long-term data from all MFS patients undergoing VSARR using David's technique at our center from 2007-2018 were analyzed. We included 56 patients with a mean age of 32.3 ± 12.3 years. Logistic EuroSCORE was 7.96 ± 5.2. Among others concomitant surgical procedures included aortic arch surgery (8.9%), mitral valve repair (23.2%) and replacement (1.7%). There were no operative deaths, nor in-hospital-mortality. One patient underwent re-exploration for bleeding, dialysis and pacemaker implantation was required in one case each. There was no occurrence of low-output syndrome nor neurological complications. Significant gender differences were not found, except for intraoperative blood transfusion occurring significantly more often in the female gender (p = 0.009). Despite significantly longer procedural times, concomitant surgery did not negatively impact overall outcome. Freedom of reoperation of the aortic root was 100% at 1 year, 97.7% at 8 years. Until last follow-up (61 ± 38 month) all patients survived, with no evidence of endocarditis. We emphasize once more that VSARR using David's procedure is a safe method for MFS patients with excellent long-term results even if concomitant procedures are performed.

Hyperbilirubinaemia after cardiac surgery: the point of no return

Aims

The occurrence of hyperbilirubinaemia after heart surgery using cardiopulmonary bypass or post‐operative heart failure is fairly common. We investigated the incidence, predictive value, and post‐operative outcome of hyperbilirubinaemia after cardiac surgery in an effort to identify potential risk factors and significance on clinical outcome.

Methods and results

Between 2006 and 2016, 1272 (10.1%) out of 12 556 patients developed hyperbilirubinaemia, defined as bilirubin concentration >3 mg/dL, during post‐operative course at our institution. All patients who were operated using cardiopulmonary bypass were included. Hepatic dysfunction was diagnosed preoperatively in 200 patients (15.7%), whereas mean model of end‐stage liver disease score was 11.22 ± 4.99. Early mortality was 17.4% with age [hazard ratio (HR) 1.019, 95% confidence interval (CI) 1.008–1.029; P = 0.001], diabetes (HR 1.115, CI 1.020–1.220; P = 0.017), and emergent procedures (HR 1.315, CI 1.012–1.710) as multivariate predictors. Post‐operative predictors were low‐output syndrome (HR 3.193, 95% CI 2.495–4.086; P < 0.001), blood transfusion (HR 1.0, CI 1.0–1.0; P < 0.001), and time to peak bilirubin (HR 1.1, CI 1.0–1.1; P < 0.001). We found an increased correlation with mortality at 3.5 post‐operative day as well as an optimal cut‐off value for bilirubin of 5.35 mg/dL. A maximum bilirubin of 25.5 mg/dL was associated with 99% mortality. Survival analysis showed significantly decreased survival for patients who developed late, rather than early, hyperbilirubinaemia.

Conclusions

Post‐operative hyperbilirubinaemia is a prevalent threat after cardiopulmonary bypass, associated with high early mortality. The timing and amount of peak bilirubin concentration are linked to the underlying pathology and are predictors of post‐operative outcome. Patients with late development of steep hyperbilirubinaemia warrant meticulous post‐operative care optimizing cardiac and end organ functions before reaching the point of no return.

Results of concomitant groin-free percutaneous temporary RVAD support using a centrifugal pump with a double-lumen jugular venous cannula in LVAD patients

Background

Modern left ventricular assist devices (LVAD) have evolved to become standard of care in severe heart failure (HF) patients. Right HF (RHF) is a major complication responsible for early mortality. Several techniques for temporary right ventricular assist device (t-RVAD) have been described before, baring relevant disadvantages such as limited mobilization or the need for re-thoracotomy. We describe the results of an alternative technique for t-RVAD using the Tandem Heart™ with ProtekDuo™ cannula.

Methods

An institutional retrospective single centre outcome analysis was performed including all permanent LVAD recipients with concomitant groin-free t-RVAD support.

Results

Between October 2015 and September 2017, 11 patients (10 male, 90.9%) were included. Preoperative NYHA class was 3.8±0.75 and INTERMACS class 3.5±1.5. Four (36.4%) patients were already on mechanical circulatory support (MCS) at time of implantation with 4 (36.4%) patients already on inotropic support. All LVAD implantations were performed on-pump and 3 cases (27.3%) were re-do cases. Mean t-RVAD duration was 16.8±9.5 days. Ten patients (90.9%) could be weaned from temporary RVAD support, 1 patient deceased on support. Mean ICU stay was 23.8±16.5 days, while 30-day survival was 72.7%. Follow-up was complete with 214.7±283 days. Three patients (27.3%) died following multi-organ failure (MOF), 1 patient (9.1%) following intracranial bleed 12 days after t-RVAD explantation. No severe t-RVAD associated complications were observed.

Conclusions

Our technique allows for safe groin-free t-RVAD providing all advantages of percutaneous implantation including complete mobilization and bedside explantation without any need for operation.

Mode of presentation and mortality amongst patients hospitalized with heart failure? A report from the First Euro Heart Failure Survey

BACKGROUND

Heart failure is heterogeneous in aetiology, pathophysiology, and presentation. Despite this diversity, clinical trials of patients hospitalized for HF deal with this problem as a single entity, which may be one reason for repeated failures.

METHODS

The first EuroHeart Failure Survey screened consecutive deaths and discharges of patients with suspected heart failure during 2000-2001. Patients were sorted into seven mutually exclusive hierarchical presentations: (1) with cardiac arrest/ventricular arrhythmia; (2) with acute coronary syndrome; (3) with rapid atrial fibrillation; (4) with acute breathlessness; (5) with other symptoms/signs such as peripheral oedema; (6) with stable symptoms; and (7) others in whom the contribution of HF to admission was not clear.

RESULTS

The 10,701 patients enrolled were classified into the above seven presentations as follows: 260 (2%), 560 (5%), 799 (8%), 2479 (24%), 1040 (10%), 703 (7%), and 4691 (45%) for which index-admission mortality was 26%, 20%, 10%, 8%, 6%, 6%, and 4%, respectively. Compared to those in group 7, the hazard ratios for death during the index admission were 4.9 (p ≤ 0.001), 4.0 (p < 0.001), 2.2 (p < 0.001), 2.1 (p < 0.001), 1.4 (p < 0.04) and 1.4 (p = 0.04), respectively. These differences were no longer statistically significant by 12 weeks.

CONCLUSION

There is great diversity in the presentation of heart failure that is associated with very different short-term outcomes. Only a minority of hospitalizations associated with suspected heart failure are associated with acute breathlessness. This should be taken into account in the design of future clinical trials.

Modulating ATP binding cassette transporters in papillary renal cell carcinoma type 2 enhances its response to targeted molecular therapy

Papillary renal cell carcinoma (PRCC) is the most common nonclear cell RCCs and is known to comprise two histological subtypes. PRCC2 is more aggressive and is molecularly distinct from the other subtypes. Despite this, PRCCs are treated together as one entity, and they show poor response to the current therapies that do not target pathways implicated in their pathogenesis. We have previously detected ABCC2 (an ABC transporter), VEGF, and mTOR pathways to be enriched in PRCC2. In this study, we assess the therapeutic potential of targeting these pathways in PRCC2. Twenty RCC cell lines from the Cancer Cell Encyclopedia were compared to the Cancer Genome Atlas PRCC cohort (290), to identify representative PRCC2 cell lines. Cell lines were further validated in xenograft models. Selected cell lines were treated in vitro and in vivo (mice models) under five different conditions, untreated, anti-VEGF (sunitinib), ABCC2 blocker (MK571), mTOR inhibitor (everolimus) and sunitinib + MK571. Sunitinib +ABCC2 blocker group showed a significant response to therapy compared to the other treatment groups both in vitro (P ≤ 0.0001) and in vivo (P = 0.0132). ABCC2 blockage resulted in higher sunitinib uptake, both in vitro (P = 0.0016) and in vivo (P = 0.0031). Everolimus group demonstrated the second best response in vivo. The double-treatment group showed the highest apoptotic rate and lowest proliferation rate. There is an urgent need for individualized therapies of RCC subtypes that take into account their specific biology. Our results demonstrate that combined targeted therapy with sunitinib and ABCC2 blocker in PRCC2 has therapeutic potential. The results are likewise potentially significant for other ABCC2 high tumors. However, the results are preliminary and clinical trials are needed to confirm these effects in PRCC2 patients.

Sunitinib induces early histomolecular changes in a subset of renal cancer cells that contribute to resistance

Sunitinib is the standard-of-care, first-line treatment for advanced renal cell carcinoma (RCC). Characteristics of treatment-resistant RCC have been described; however, complex tumor adaptation mechanisms obstruct the identification of significant operators in resistance. We hypothesized that resistance is a late manifestation of early, treatment-induced histomolecular alterations; therefore, studying early drug response may identify drivers of resistance. We describe an epithelioid RCC growth pattern in RCC xenografts, which emerges in sunitinib-sensitive tumors and is augmented during resistance. This growth modality is molecularly and morphologically related to the RCC spheroids that advance during in vitro treatment. Based on time-lapse microscopy, mRNA and microRNA screening, and tumor behavior-related characteristics, we propose that the spheroid and adherent RCC growth patterns differentially respond to sunitinib. Gene expression analysis indicated that sunitinib promoted spheroid formation, which provided a selective survival advantage under treatment. Functional studies confirm that E-cadherin is a key contributor to the survival of RCC cells under sunitinib treatment. In summary, we suggest that sunitinib-resistant RCC cells exist in treatment-sensitive tumors and are histologically identifiable.-Lichner, Z., Saleeb, R., Butz, H., Ding, Q., Nofech-Mozes, R., Riad, S., Farag, M., Varkouhi, A. K., dos Santos, C. C., Kapus, A., Yousef, G. M. Sunitinib induces early histomolecular changes in a subset of renal cancer cells that contribute to resistance.

Social determinants of self-reported health for Canada's indigenous peoples: a public health approach

OBJECTIVE

In Canada, indigenous peoples suffer from a multitude of health disparities. To better understand these disparities, this study aims to examine the social determinants of self-reported health for indigenous peoples in Canada.

STUDY DESIGN

This study uses data from Statistics Canada's Aboriginal Peoples Survey 2012.

METHODS

Multinomial logistic regression models were used to examine how selected social determinants of health are associated with self-reported health among off-reserve First Nations and Métis peoples in Canada.

RESULTS

Our analysis shows that being older, female, and living in urban settings were significantly associated with negative ratings of self-reported health status among the indigenous respondents. Additionally, we found that higher income and levels of education were strongly and significantly associated with positive ratings of self-reported health status. Compared with indigenous peoples with an education level of grade 8 or lower, respondents with higher education were 10 times (5.35-22.48) more likely to report 'excellent' and 'very good' health. Respondents who earned more than $40,000 annually were three times (2.17-4.72) more likely to report 'excellent' and 'very good' health compared with those who earned less than $20,000 annually. When interacted with income, we also found that volunteering in the community is associated with better self-reported health.

CONCLUSIONS

There are known protective determinants (income and education) and risk determinants (location of residence, gender, and age) which are associated with self-reported health status among off-reserve First Nations and Métis peoples. For indigenous-specific determinants, volunteering in the community appears to be associated with self-perceived health status. Thus, addressing these determinants will be necessary to achieve better health outcomes for indigenous peoples in Canada. Next steps include developing indigenous-specific social determinants of health indicators that adequately measure culture, connection, and community.

Pulmonary valve and right ventricular outflow tract surgery in adults: 23-year experience

BACKGROUND

Surgery of the pulmonary valve, right ventricular outflow tract, and pulmonary artery falls under the domain of paediatric cardiac surgery. However, 97 adult patients underwent such operations in our institution from 1993 to 2016.

AIM

This study aims to analyse preoperative risk factors, intraoperative data, postoperative outcomes, and long-term survival to identify the potential predictors of mortality and high-risk patients.

METHODS

We divided our patient cohort into three groups in accordance with surgical indications: 17 patients with pulmonary valve endocarditis (group A), 70 patients with congenital defects involving the pulmonary valve (group B), and 10 patients who underwent pulmonary valve surgery for other indications, such as tumour or other acquired valvular disease (group C).

RESULTS

Gender distribution was comparable in all the three groups, with about 40% of the total number of patients being female. The mean age was 35.9 ± 15.7 years. Sixty (61.9%) patients had a history of cardiac surgery. Various concomitant cardiac surgical procedures were necessary in 49 (50.5%) cases. There were two (11.8%) in-hospital deaths in group A, two (2.9%) in group B, and none in group C. Within the mean follow-up time of 6.6 ±7.2 years, three (17.7%) patients in group A, two (2.9%) in group B, and four (40%) in group C died.

CONCLUSIONS

Adult patients with pulmonary valve disease are often previously heart-operated and often need concomitant procedures. The operative risk in patients with pulmonary valve endocarditis is high. Surgery of congenital defects of the pulmonary valve is safe and can be performed with excellent outcomes.

GATA3 frameshift mutation promotes tumor growth in human luminal breast cancer cells and induces transcriptional changes seen in primary GATA3 mutant breast cancers

The GATA3 transcription factor is one of the most frequently mutated genes in breast cancer. Heterozygous mutations, mostly frameshifts, are seen in 15% of estrogen receptor positive breast cancers, the subtype in which these mutations are almost exclusively found. Mouse studies have shown that Gata3 is critical for breast development and that GATA3 gene dosage affects breast tumor progression. Human patient data have shown that high Gata3 expression, a feature of luminal subtype breast cancers, is associated with a better prognosis. Although the frequency of GATA3 mutation suggests an important role in breast cancer development or progression, there is little understanding of how mutations in GATA3 affect its function in luminal breast epithelial cells and what gene expression changes result as a consequence of the mutations. Here, using gene editing, we have created two sets of isogenic human luminal breast cancer cell lines with and without a hotspot truncating GATA3 mutation. GATA3 mutation enhanced tumor growth in vivo but did not affect sensitivity to clinically used hormonal therapies or chemotherapeutic agents. We identified genes with upregulated and downregulated expression in GATA3 mutant cells, a subset of which was concordantly differentially expressed in GATA3 mutant primary luminal breast cancers. Addback of mutant GATA3 recapitulated mutation-specific gene expression changes and enhanced soft agar colony formation, suggesting a gain of function for the mutant protein.

Extracorporeal life support with left ventricular decompression-improved survival in severe cardiogenic shock: results from a retrospective study

Objective

Extracorporeal life support (ECLS) is a life-saving procedure used in the treatment of severe cardiogenic shock. Within this retrospective single centre study, we examined our experience in this critically ill patient cohort to assess outcomes and clinical parameters by comparison of ECLS with or without selective left ventricular decompression.

Methods

Between 2004 and 2014 we evaluated 48 adult patients with INTERMACS level 1 heart failure (age 49.7 ± 19.5 years), who received either central ECLS with (n = 20, 41.7%) or ECLS without (n = 28, 58.3%, including 10 peripheral ECLS) integrated left ventricular vent in our retrospective single centre trial.

Results

Follow up was 100% with a mean of 0.83 ± 1.85 years. Bridge to ventricular assist device was feasible in 29.2% (n = 14), bridge to transplant in 10.4% (n = 5) and bridge to recovery in 8.3% (n = 4). Overall 30-day survival was 37.5%, 6-month survival 27.1% and 1-year survival 25.0%. ECLS support with left ventricular decompression showed favourable 30-day survival compared to ECLS without left ventricular decompression (p = 0.034). Thirty-day as well as long-term survival did not differ between the subgroups (central ECLS with vent, ECLS without vent and peripheral ECLS without vent). Multivariate logistic regression adjusted for age and gender revealed ECLS without vent as independent factor influencing 30-day survival.

Conclusion

ECLS is an established therapy for patients in severe cardiogenic shock. Independent of the ECLS approach, 30-day mortality is still high but with superior 30-day survival for patients with ECLS and left ventricular venting. Moreover, by unloading the ventricle, left ventricular decompression may provide an important time window for recovery or further treatment, such as bridge to bridge or bridge to transplant.

Extracorporeal life support and digoxin-specific Fab fragments for successful management of Taxus baccata intoxication with low output and ventricular arrhythmia

INTRODUCTION

Yew plants are evergreen shrubs which are widely spread throughout the northern hemisphere. Taxane alkaloid derivatives, mainly taxine B, represent the main toxins of Taxus baccata and are highly cardiotoxic. Due to the lack of randomized clinical trials, case reports on accidental or suicidal yew intoxications build the only source of knowledge of clinical treatment options.

CASE REPORT

We report the case of a suicidal yew ingestion admitted to our hospital under prolonged cardiopulmonary resuscitation due to pulseless electrical activity. Extra-corporeal life support (ECLS) was established to maintain adequate organ perfusion. Repeated administration of digoxin-specific Fab antibody fragments, which cross-react with taxine, was associated with an immediate conversion from asystole to broad-complex bradycardia and a gradual normalization of the electrocardiogram (ECG). This was paralleled by a recovery of the cardiac function and weaning from the ECLS. The taxine metabolite 3,5-dimethoxyphenol could be detected by mass spectrometry before but not after the first Fab-fragment treatment. In contrast, the total amount of taxine (including the neutralized, Fab fragment-bound fraction) was increased after each Fab fragment administration, suggesting an accumulation of neutralized, since antibody-bound taxine in the blood by anti-digoxin Fab fragments.

DISCUSSION

In conclusion, the successful clinical course of this case suggests a benefit of an early anti-digoxin Fab-fragment administration for the treatment of yew intoxication.

Surgery for Infective Endocarditis: Outcomes and Predictors of Mortality in 360 Consecutive Patients

BACKGROUND A retrospective analysis was conducted of the early and long-term outcomes after surgery for infective endocarditis (IE). MATERIAL AND METHODS We included 360 patients with IE operated upon between 1993 and 2012. The primary endpoint was overall cumulative postoperative survival at 30 days. Secondary endpoints were early postoperative outcomes and complication rates. Factors associated with 30-day mortality were analyzed. RESULTS Mean age was 58.7±14.7 years and 26.9% (n=97) were female. The mean follow-up was 4.41±4.53 years. Postoperative survival was 81.7% at 30 days, 69.4% at 1 year, 63.3% at 5 years, and 63.3% at 10 years. Non-survivors were significantly older (p=0.014), with higher NYHA Class (p=0.002), had higher rates of preoperative diabetes mellitus (p=0.005), renal failure (p=0.001), and hepatic disease (p=0.002). Furthermore, non-survivors had higher baseline alanine aminotransferase (ALT, p=0.048), aspartate transaminase (AST, p=0.027), bilirubin (p=0.013), white cell count (WCC, p=0.034), and CRP (p=0.049). Factors associated with 30-day mortality were longer duration of surgery, CPB, and aortic cross-clamping times (p<0.001, p<0.001, and p=0.003, respectively), as well as higher RBC, FFP, and platelet transfusion requirements (p<0.001, p=0.005, and p<0.001, respectively). Multivariate logistic regression analysis revealed liver cirrhosis (OR 4.583, 95-CI: 1.096-19.170, p=0.037) and longer CPB time (OR 1.025, 95-CI 1.008-1.042, p=0.004) as independent predictors of 30-day mortality. CONCLUSIONS Surgical treatment of IE shows satisfactory early, midterm, and long-term results. Multivariate logistic regression analysis revealed cirrhosis and longer CPB time as independent predictors of 30-day mortality.

Abstract 2464: Papillary renal cell carcinoma, proposal of a new classification system based on integrated molecular, histological and clinical analysis

Background:

Papillary Renal Cell Carcinoma (PRCC) is divided into histological subtypes 1 and 2. Type 2 is known to have worse clinical behavior. A number of PRCC cases (~ 50%), fail to meet all reported morphological criteria for either type, hence are best characterized as PRCC not otherwise specified (NOS). There are yet no reliable markers to resolve the PRCC NOS category. That in turn reflects the clinical dilemma of how to manage these patients.

Experimental Design:

PRCC patient cohort of 115 cases was selected for the study. Cases were subtyped histologically into PRCC types 1, 2 and NOS. Potentially distinguishing markers ABCC2, CA9, SAll4, and BCL2 selected from our previous genomic analysis, were assessed by immunohistochemistry (IHC). A total of 24 cases were further selected for molecular analysis using miRNA expression and copy number variation (CNV). Univariate and multivariate survival analysis were performed using Log rank test and cox proportionate hazards.

Results:

Markers ABCC2, CA9 exhibited distinct staining patterns between the two classic PRCC subtypes; and successfully classified many of the PRCC NOS (45%) cases. Moreover, immunomarkers revealed a third distinct subtype of PRCC (35% of the PRCC cohort). Molecular

testing using miRNA expression and CNV analysis confirmed the presence of three distinct molecular signatures corresponding to the 3 subtypes. On univariate analysis DFS was significantly enhanced in the type1 versus 2& 3 (p value 0.047). PRCC subtyping retained

significance on multivariate analysis (p value 0.025, HR:6, 95% CI 1.25 to 32.2) .

Conclusion:

We propose a new classification system of PRCC integrating morphological, immunophenotypical, and molecular analysis. Our classification reveals a 3rd PRCC subtype that was not previously described. This subtype has overlapping morphology of with PRCC types 1 and 2, hence would be subtyped as PRCC NOS in the current classification. Molecularly PRCC type 3 has a distinct signature and clinically it behaves similar to PRCC type 2. The new classification stratifies PRCC patients into clinically relevant subgroups and has significant future implications on the management of PRCC.

Citation Format: Rola Saleeb, Mina Farag, Fadi Brimo, Fabio Rotondo, Pamela Plant, George Yousef. Papillary renal cell carcinoma, proposal of a new classification system based on integrated molecular, histological and clinical analysis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2464. doi:10.1158/1538-7445.AM2017-2464

Abstract 811: Histological heterogeneity contributes to sunitinib resistance in clear cell renal cell carcinoma

Introduction: The receptor tyrosine kinase (RTK) inhibitor sunitinib is the first line treatment for advanced clear cell renal cell carcinoma (ccRCC). Sunitinib inhibits angiogenesis via blocking signaling through VEGFR. About 80% of patients develop resistance after a drug-sensitive period. Molecular changes early in treatment may impact drug resistance, but are poorly understood.

Experimental Procedures: ACHN, 786-O and Renca cell lines were treated with 1 µM sunitinib. NSG mice were s.c. xenografted with the model cell lines and were treated with sunitinib at 40 mg/kg/day dose. mRNA expression was screened using Illumina HT-12 bead chip array and miRNA expression was assessed by Nanostring nCounter assay. R statistical packages were used for data processing. Reactome and miRPath softwares were used for downstream analysis.

Results: Sunitinib treatment of ccRCC xenografts led to several early changes in tumor histology, such as the emergence of live tumor areas within the necrotic spaces. These areas showed membranous staining for E-cadherin, and β-catenin, while the rest of the tumor and vehicle-treated tumors were negative. In vitro model cell lines developed cancer spheroids when treated with sunitinib. Cancer spheroids were highly tumorigenic and metastatic, and expressed several established cancer stem cell markers. ccRCC cancer spheres, but not the 2D adherent cells, showed membranous staining for E-cadherin and β-catenin; similarly to the live tumor areas observed in

in vivo sunitinib treatment. In vitro inhibition of E-cadherin by EGTA or by siRNA, interfered with viability of sunitinib treated ccRCC cell lines.

Conclusions: Sunitinib treatment causes early phenotypic changes of the tumor in vivo and in vitro. The formation of highly metastatic and tumorigenic cancer spheres in model cell lines is the most prominent effect in vitro. We provide preliminary evidence that sunitinib induced in vitro cancer spheres and the live tumor areas that survive within necrotic patches of the sunitinib-treated xenografts, are related. Finally, membranous expression of E-cadherin enhances the survival of ccRCC cell lines under sunitinib treatment.

Citation Format: Zsuzsanna Lichner, Rola Saleeb, Henriett Butz, Roy Nofech-Mozes, Sara Riad, Mina Farag, Andras Kapus, George Yousef. Histological heterogeneity contributes to sunitinib resistance in clear cell renal cell carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 811. doi:10.1158/1538-7445.AM2017-811