Sebastian Frees

Genotyping NAT2 with only two SNPs (rs1041983 and rs1801280) outperforms the tagging SNP rs1495741 and is equivalent to the conventional 7-SNP NAT2 genotype.

Genotyping N-acetyltransferase 2 (NAT2) is of high relevance for individualized dosing of antituberculosis drugs and bladder cancer epidemiology. In this study we compared a recently published tagging single nucleotide polymorphism (SNP) (rs1495741) to the conventional 7-SNP genotype (G191A, C282T, T341C, C481T, G590A, A803G and G857A haplotype pairs) and systematically analysed if novel SNP combinations outperform the latter. For this purpose, we studied 3177 individuals by PCR and phenotyped 344 individuals by the caffeine test. Although the tagSNP and the 7-SNP genotype showed a high degree of correlation (R=0.933, P<0.0001) the 7-SNP genotype nevertheless outperformed the tagging SNP with respect to specificity (1.0 vs. 0.9444, P=0.0065). Considering all possible SNP combinations in a receiver operating characteristic analysis we identified a 2-SNP genotype (C282T, T341C) that outperformed the tagging SNP and was equivalent to the 7-SNP genotype. The 2-SNP genotype predicted the correct phenotype with a sensitivity of 0.8643 and a specificity of 1.0. In addition, it predicted the 7-SNP genotype with sensitivity and specificity of 0.9993 and 0.9880, respectively. The prediction of the NAT2 genotype by the 2-SNP genotype performed similar in populations of Caucasian, Venezuelan and Pakistani background. A 2-SNP genotype predicts NAT2 phenotypes with similar sensitivity and specificity as the conventional 7-SNP genotype. This procedure represents a facilitation in individualized dosing of NAT2 substrates without losing sensitivity or specificity.

R.E.N.A.L. Score Outperforms PADUA Score, C-Index and DAP Score for Outcome Prediction of Nephron Sparing Surgery in a Selected Cohort

PURPOSE Several nephrometry scores have been proposed to predict perioperative outcomes in renal surgery. We evaluated which nephrometry score correlates best with the MIC (margin, ischemia and complications) score and quantitative perioperative outcomes in nephron sparing surgery. MATERIALS AND METHODS Data on 188 patients undergoing nephron sparing surgery were retrospectively investigated for patient, operative and tumor characteristics. Nephrometry scores, including R.E.N.A.L. (radius, exophytic/endophytic properties, nearness of tumor to collecting system or sinus, anterior/posterior, hilar tumor touching the main renal artery or vein and location relative to polar lines), PADUA (preoperative aspects and dimensions used for an anatomical), C-index (concordance index) and DAP (diameter-axial-polar), were measured on preoperative computerized tomography or magnetic resonance imaging and coded continuously and categorically. Parameters pertaining to tumor margin, ischemia and complications were recorded as binary scores and classified as MIC achievement. Operative time, estimated blood loss, warm ischemia time and hospital stay were recorded as quantitative perioperative outcomes. RESULTS The R.E.N.A.L. score correlated best with MIC and quantitative perioperative outcomes. The continuously coded R.E.N.A.L. score was predictive of MIC on univariate analysis (OR 0.75, 95% CI 0.58-0.97, p = 0.03) and it had the best predictive value on multivariate logistic regression analysis (OR 0.31, 95% CI 0.18-0.82, p = 0.03). The C-index but not the PADUA or the DAP score was predictive of MIC on univariate and multivariate logistic regression analysis. MIC achievement rates were significantly higher for low than for high complexity tumors as assessed by categorically coded R.E.N.A.L. score, C-index and DAP scores. Continuously coded R.E.N.A.L. and PADUA scores positively correlated with operative time, warm ischemia time and hospital stay. The C-index and the DAP score correlated with warm ischemia time. CONCLUSIONS Of 4 nephrometry scores the R.E.N.A.L. score correlated best with MIC achievement and quantitative perioperative outcomes of nephron sparing surgery.

Cellular Adaptation to VEGF-Targeted Antiangiogenic Therapy Induces Evasive Resistance by Overproduction of Alternative Endothelial Cell Growth Factors in Renal Cell Carcinoma

Vascular endothelial growth factor (VEGF)–targeted antiangiogenic therapy significantly inhibits the growth of clear cell renal cell carcinoma (RCC). Eventually, therapy resistance develops in even the most responsive cases, but the mechanisms of resistance remain unclear. Herein, we developed two tumor models derived from an RCC cell line by conditioning the parental cells to two different stresses caused by VEGF-targeted therapy (sunitinib exposure and hypoxia) to investigate the mechanism of resistance to such therapy in RCC. Sunitinib-conditioned Caki-1 cells in vitro did not show resistance to sunitinib compared with parental cells, but when tested in vivo, these cells appeared to be highly resistant to sunitinib treatment. Hypoxia-conditioned Caki-1 cells are more resistant to hypoxia and have increased vascularity due to the upregulation of VEGF production; however, they did not develop sunitinib resistance either in vitro or in vivo. Human endothelial cells were more proliferative and showed increased tube formation in conditioned media from sunitinib-conditioned Caki-1 cells compared with parental cells. Gene expression profiling using RNA microarrays revealed that several genes related to tissue development and remodeling, including the development and migration of endothelial cells, were upregulated in sunitinib-conditioned Caki-1 cells compared with parental and hypoxia-conditioned cells. These findings suggest that evasive resistance to VEGF-targeted therapy is acquired by activation of VEGF-independent angiogenesis pathways induced through interactions with VEGF-targeted drugs, but not by hypoxia. These results emphasize that increased inhibition of tumor angiogenesis is required to delay the development of resistance to antiangiogenic therapy and maintain the therapeutic response in RCC.

Differences in Overall and Cancer-specific Survival of Patients Presenting With Chromophobe Versus Clear Cell Renal Cell Carcinoma: A Propensity Score Matched Analysis

OBJECTIVES To investigate prognostic parameters for the oncological outcome of patients treated for chromophobe renal cell carcinoma (chRCC) in comparison with patients treated for clear cell RCC (ccRCC) using propensity score matching for survival analysis. METHODS From 1969 to 2009, we identified 1010 from 3567 patients with RCC. Survival was analyzed using Kaplan-Meier estimate for histological subtypes including 109 chRCC and 901 ccRCC. Uni- and multivariate Cox regression was used to analyze prognostic factors for overall survival (OS) and cancer-specific survival (CSS). Propensity score matching was performed to adjust for differences in patient characteristics among histological subgroups. RESULTS The median follow-up was 61 months (range 0-289). chRCC showed longer OS (5 year, 90.1%; 10 year, 74.2%; 15 year, 61.4%) and CSS (94.2%, 89.7%, 89.7%) compared with ccRCC (OS 75.7%, 54.9%, 46.1% and CSS 84.7%, 75.4%, 72.2%; P = .002). Multivariate Cox regression revealed histology as a significant prognostic factor. Propensity score matching showed a difference in 72.4% (OS) and 87.2% (CSS) of matching attempts confirming the significant impact of histology. Univariate Cox regression showed nephron sparing surgery, no metastasis and no symptoms at presentation, age <65, eosinophilic features, low American Society of Anesthesiologists score, and Charlson Comorbidity Index to be beneficial for CSS. Only age at surgery, metastasis at presentation, and American Society of Anesthesiologists and Charlson Comorbidity Index scores were significant factors for OS in chRCC patients. CONCLUSION ChRCC appears to have a favorable outcome compared with ccRCC. Even after adjustment for differences in characteristics known to have an influence on survival by propensity score matching, histology remains a significant prognostic factor.

Metabolische Langzeitprobleme bei der Harnableitung

Metabolic long-term complications and consequences after urinary diversion are somewhat neglected. Subclinical metabolic disturbances are quite common; however, complications are rare. The absorptive surface of the bowel segment is lost for the physiological function of the gastrointestinal tract. Some studies demonstrated that at least some of the absorbent and secreting properties of the bowel are preserved if exposed to urine. For each bowel segment typical complications are reported. Using ileal and/or colon segments, hyperchloremic metabolic acidosis may occur. Studies demonstrated that metabolic effects are not as severe as suspected and could be prevented if a prophylactic treatment is started early.The resection of ileal segments is responsible for malabsorption of vitamin B(12) and bile acid; when using colonic segments, electrolyte disturbances are more common. Careful patient selection, meticulous follow-up and prophylactic treatment are crucial to prevent metabolic complications.

Inhibition of endoplasmic reticulum chaperone protein glucose-regulated protein 78 potentiates anti-angiogenic therapy in renal cell carcinoma through inactivation of the PERK/eIF2α pathway.

Tumor microenvironments are characterized by decreased oxygen and nutrition due to the rapid and progressive nature of tumors and also stresses induced by several anti-tumor therapies. These intense cell stressors trigger a protective cell survival mechanism heralded by the unfolded protein response (UPR). The UPR is induced by an accumulation of unfolded proteins in the endoplasmic reticulum (ER) following cell starvation. Although the ER stress response is implicated in cytoprotection, its precise role during anti-angiogenic therapy remains unclear. One of the major proteins involved in ER stress is glucose-regulated protein 78 (GRP78), which binds to unfolded proteins and dissociates from membrane-bound ER stress sensors. To determine the role of ER stress responses during anti-angiogenic therapy and the potential role of GRP78 in combined therapy in renal cell carcinoma (RCC), we used GRP78 overexpressing or knockdown RCC cells under hypoxic or hypoglycemic conditions in vitro and in animal models treated with sunitinib. Here, we report that GRP78 plays a crucial role in protecting RCC cells from hypoxic and hypoglycemic stress induced by anti-angiogenic therapy. Knockdown of GRP78 using siRNA inhibited cancer cell survival and induced apoptosis in RCC cells in vitro and also resulted in ER stress-induced apoptosis and hypoxic/hypoglycemic stress-induced apoptosis by inactivating the PERK/eIF-2α pathway. Finally, GRP78 knockdown showed potent suppression of tumor growth and enhanced the antitumor effect of sunitinib in RCC xenografts. Our findings suggest that GRP78 may serve as a novel therapeutic target in combination with anti-angiogenic therapy for the management of RCC.

[Metabolic long-term complications after urinary diversion].

Metabolic long-term complications and consequences after urinary diversion are somewhat neglected. Subclinical metabolic disturbances are quite common; however, complications are rare. The absorptive surface of the bowel segment is lost for the physiological function of the gastrointestinal tract. Some studies demonstrated that at least some of the absorbent and secreting properties of the bowel are preserved if exposed to urine. For each bowel segment typical complications are reported. Using ileal and/or colon segments, hyperchloremic metabolic acidosis may occur. Studies demonstrated that metabolic effects are not as severe as suspected and could be prevented if a prophylactic treatment is started early.The resection of ileal segments is responsible for malabsorption of vitamin B(12) and bile acid; when using colonic segments, electrolyte disturbances are more common. Careful patient selection, meticulous follow-up and prophylactic treatment are crucial to prevent metabolic complications.

„Watchful waiting“ und aktive Überwachung kleiner Nierentumoren

The incidence of small renal masses ≤4 cm is increasing due to the widespread use of cross-sectional imaging. The majority of these represent indolent forms, but the risk for developing metastases is reported in up to 6% of patients. Particularly in old and comorbid patients surgery might be harmful overtreatment. Thus, there is an increasing demand to establish oncologically safe active surveillance protocols. Radiographic or biopsy-based biological markers to appropriately designate candidates for active surveillance are currently the focus of research.ZusammenfassungDie Inzidenz kleiner Nierenzellkarzinome ≤4 cm steigt mit der ausgedehnten Nutzung von Schnittbildgebung. Die Tumoren weisen meist wenig Aggressivität auf, wobei das Risiko der Metastasierung trotzdem bis zu 6 % betragen kann. Insbesondere für alte komorbide Patienten könnte eine Operation somit eine schädigende Übertherapie darstellen. Die Etablierung einer onkologisch sicheren aktiven Überwachung gewinnt in dieser Situation zunehmend an Bedeutung, so dass klinische, radiologische und biopsiebasierte biologische Marker für die Auswahl und die Überwachung geeigneter Patienten aktuell im Fokus der Forschung stehen.AbstractThe incidence of small renal masses ≤4 cm is increasing due to the widespread use of cross-sectional imaging. The majority of these represent indolent forms, but the risk for developing metastases is reported in up to 6% of patients. Particularly in old and comorbid patients surgery might be harmful overtreatment. Thus, there is an increasing demand to establish oncologically safe active surveillance protocols. Radiographic or biopsy-based biological markers to appropriately designate candidates for active surveillance are currently the focus of research.

Calcium-sensing receptor (CaSR) promotes development of bone metastasis in renal cell carcinoma

Bone metastasis is an important prognostic factor in renal cell carcinoma (RCC). The calcium-sensing receptor (CaSR) has been associated with bone metastasis in several different malignancies. We analyzed the impact of CaSR in bone metastasis in RCC in vitro and in vivo. The RCC cell line 786-O was stably transfected with the CaSR gene and treated with calcium alone or in combination with the CaSR antagonist NPS2143. Afterwards migration, adhesion, proliferation and prominent signaling molecules were analyzed. Calcium treated CaSR-transfected 768-O cells showed an increased adhesion to endothelial cells and the extracellular matrix components fibronectin and collagen I, but not to collagen IV. The chemotactic cell migration and proliferation was also induced by calcium. The activity of SHC, AKT, ERK, P90RSK and JNK were enhanced after calcium treatment of CaSR-transfected cells. These effects were abolished by NPS2143. Development of bone metastasis was evaluated in vivo in a mouse model. Intracardiac injection of CaSR-transfected 768-O cells showed an increased rate of bone metastasis. The results indicate CaSR as an important component in the mechanism of bone metastasis in RCC. Therefore, targeting CaSR might be beneficial in patients with bone metastatic RCC with a high CaSR expression.

Continent Anal Urinary Diversion in Classic Bladder Exstrophy: 45-Year Experience

OBJECTIVE To evaluate the long-term outcomes in patients with classic bladder exstrophy and continent anal urinary diversion (CAD) for continence, upper urinary tract status, secondary malignancies, and sexual function. PATIENTS AND METHODS The medical records of 82 exstrophy patients having undergone CAD in our department between 1970 and 2015 were reviewed. Patients were invited for follow-up examinations and asked to complete validated questionnaires relating to sexual function. RESULTS Thirty-two of 57 eligible patients with a median follow-up of 23.9 years were included in the study. Ninety-seven percent of patients were fully continent during daytime. Upper urinary tract and renal function remained stable in 75% and 87%, respectively. Five patients developed secondary malignancies originating from the rectal reservoir. Forty-one percent received prophylactic alkaline substitution. Sexual function as measured by the Female Sexual Function Index and the International Index on Erectile Function was negatively affected in all domains in both genders. Eighty-six percent of patients had a stable relationship and 35% were married. Five women conceived a total of 6 healthy children. Paternity rate was 40%. CONCLUSION CAD constitutes an effective treatment option with acceptable long-term outcomes in exstrophy patients in whom all attempts at restoring the lower urinary tract have failed. Long-term follow-up of the upper urinary tract, assessment of acid-base balance, and endoscopy of the rectosigmoid reservoir are paramount for the safety of this type of management. Evaluation of sexual dysfunction should be an active part of follow-up.