Markus Krebs

68Ga-PSMA-PET/CT in Patients With Biochemical Prostate Cancer Recurrence and Negative 18F-Choline-PET/CT.

Purpose Investigating the value of 68Ga-PSMA-PET/CT in biochemically recurring prostate cancer patients with negative 18F-choline-PET/CT. Patients and Methods One hundred thirty-nine consecutive patients with biochemical recurrence after curative (surgery and/or radiotherapy) therapy were offered participation in this sequential clinical imaging approach. Patients first underwent an 18F-choline-PET/CT. If negative, an additional 68Ga-PSMA-PET/CT was offered. One hundred twenty-five of 139 eligible patients were included in the study; 32 patients underwent additional 68Ga-PSMA-PET/CT. Patients with equivocal findings (n = 5) on 18F-choline-PET/CT and those who declined the additional 68Ga-PSMA-PET/CT (n = 9) were excluded. Images were analyzed visually for the presence of suspicious lesions. Findings on PET/CT were correlated with PSA level, PSA doubling time (dt), and PSA velocity (vel). Results The overall detection rates were 85.6% (107/125) for the sequential imaging approach and 74.4% (93/125) for 18F-choline-PET/CT alone. 68Ga-PSMA-PET/CT detected sites of recurrence in 43.8% (14/32) of the choline-negative patients. Detection rates of the sequential imaging approach and 18F-choline-PET/CT alone increased with higher serum PSA levels and PSA vel. Subgroup analysis of 68Ga-PSMA-PET/CT in 18F-choline negative patients revealed detection rates of 28.6%, 45.5%, and 71.4% for PSA levels of 0.2 or greater to less than 1 ng/mL, 1 to 2 ng/mL, and greater than 2 ng/mL, respectively. Conclusions The sequential imaging approach designed to limit 68Ga-PSMA imaging to patients with negative choline scans resulted in high detection rates. 68Ga-PSMA-PET/CT identified sites of recurrent disease in 43.8% of the patients with negative 18F-choline PET/CT scans.

Biodistribution and Radiation Dosimetry for a Probe Targeting Prostate-Specific Membrane Antigen for Imaging and Therapy

Prostate-specific membrane antigen (PSMA) is a promising target for diagnosis and treatment of prostate cancer. EuK-Subkff-68Ga-DOTAGA (68Ga-PSMA Imaging & Therapy [PSMA I&T]) is a recently introduced PET tracer for imaging PSMA expression in vivo. Whole-body distribution and radiation dosimetry of this new probe were evaluated. Methods: Five patients with a history of prostate cancer were injected intravenously with 91–148 MBq of 68Ga-PSMA I&T (mean ± SD, 128 ± 23 MBq). After an initial series of rapid whole-body scans, 3 static whole-body scans were acquired at 1, 2, and 4 h after tracer injection. Time-dependent changes of the injected activity per organ were determined. Mean organ-absorbed doses and effective doses were calculated using OLINDA/EXM. Results: Injection of 150 MBq of 68Ga-PSMA I&T resulted in an effective dose of 3.0 mSv. The kidneys were the critical organ (33 mGy), followed by the urinary bladder wall and spleen (10 mGy each), salivary glands (9 mGy each), and liver (7 mGy). Conclusion: 68Ga-PSMA I&T exhibits a favorable dosimetry, delivering organ doses that are comparable to (kidneys) or lower than those delivered by 18F-FDG.

Survival in Patients with High-Risk Prostate Cancer Is Predicted by miR-221, Which Regulates Proliferation, Apoptosis, and Invasion of Prostate Cancer Cells by Inhibiting IRF2 and SOCS3

A lack of reliably informative biomarkers to distinguish indolent and lethal prostate cancer is one reason this disease is overtreated. miR-221 has been suggested as a biomarker in high-risk prostate cancer, but there is insufficient evidence of its potential utility. Here we report that miR-221 is an independent predictor for cancer-related death, extending and validating earlier findings. By mechanistic investigations we showed that miR-221 regulates cell growth, invasiveness, and apoptosis in prostate cancer at least partially via STAT1/STAT3-mediated activation of the JAK/STAT signaling pathway. miR-221 directly inhibits the expression of SOCS3 and IRF2, two oncogenes that negatively regulate this signaling pathway. miR-221 expression sensitized prostate cancer cells for IFN-γ-mediated growth inhibition. Our findings suggest that miR-221 offers a novel prognostic biomarker and therapeutic target in high-risk prostate cancer.

MiR-205 is progressively down-regulated in lymph node metastasis but fails as a prognostic biomarker in high-risk prostate cancer.

The treatment of high-risk prostate cancer (HRPCa) is a tremendous challenge for uro-oncologists. The identification of predictive moleculobiological markers allowing risk assessment of lymph node metastasis and systemic progression is essential in establishing effective treatment. In the current study, we investigate the prognostic potential of miR-205 in HRPCa study and validation cohorts, setting defined clinical endpoints for both. We demonstrate miR-205 to be significantly down-regulated in over 70% of the HRPCa samples analysed and that reconstitution of miR-205 causes inhibition of proliferation and invasiveness in prostate cancer (PCa) cell lines. Additionally, miR-205 is increasingly down-regulated in lymph node metastases compared to the primary tumour indicating that miR-205 plays a role in migration of PCa cells from the original location into extraprostatic tissue. Nevertheless, down-regulation of miR-205 in primary PCa was not correlated to the synchronous presence of metastasis and failed to predict the outcome for HRPCa patients. Moreover, we found a tendency for miR-205 up-regulation to correlate with an adverse outcome of PCa patients suggesting a pivotal role of miR-205 in tumourigenesis. Overall, we showed that miR-205 is involved in the development and metastasis of PCa, but failed to work as a useful clinical biomarker in HRPCa. These findings might have implications for the use of miR-205 as a prognostic or therapeutic target in HRPCa.

Impact of miR-21, miR-126 and miR-221 as Prognostic Factors of Clear Cell Renal Cell Carcinoma with Tumor Thrombus of the Inferior Vena Cava

Clear cell renal cell carcinoma (ccRCC) characterized by a tumor thrombus (TT) extending into the inferior vena cava (IVC) generally indicates poor prognosis. Nevertheless, the risk for tumor recurrence after nephrectomy and thrombectomy varies. An applicable and accurate prediction system to select ccRCC patients with TT of the IVC (ccRCC/TT) at high risk after nephrectomy is urgently needed, but has not been established up to now. To our knowledge, a possible role of microRNAs (miRs) for the development of ccRCC/TT or their impact as prognostic markers in ccRCC/TT has not been explored yet. Therefore, we analyzed the expression of the previously described onco-miRs miR-200c, miR-210, miR-126, miR-221, let-7b, miR-21, miR-143 and miR-141 in a study collective of 74 ccRCC patients. Using the expression profiles of these eight miRs we developed classification systems that accurately differentiate ccRCC from non-cancerous renal tissue and ccRCC/TT from tumors without TT. In the subgroup of 37 ccRCC/TT cases we found that miR-21, miR-126, and miR-221 predicted cancer related death (CRD) accurately and independently from other clinico-pathological features. Furthermore, a combined risk score based on the expression of miR-21, miR-126 and miR-221 was developed and showed high sensitivity and specificity to predict cancer specific survival (CSS) in ccRCC/TT. Using the combined risk score we were able to classify ccRCC/TT patients correctly into high and low risk cases. The risk stratification by the combined risk score (CRS) will benefit from further cohort validation and might have potential for clinical application as a molecular prediction system to identify high- risk ccRCC/TT patients.

Long-Term Outcome of Nephron-Sparing Surgery Compared to Radical Nephrectomy for Renal Cell Carcinoma ≥4 cm - A Matched-Pair Single Institution Analysis

Purpose: We investigated the long-term oncological and functional outcome of nephron-sparing surgery/partial nephrectomy (PN) versus radical nephrectomy (RN) for any renal cell carcinoma (RCC) ≥4 cm. Patients and Methods: Between 1997 and 2013, we identified 128 patients undergoing PN for RCC ≥4 cm and matched this collective to 128 patients undergoing RN. We then compared overall survival (OS), cancer-specific survival (CSS), progression-free survival (PFS) and functional parameters in both groups. The median follow-up time was 58 months (3-210 months). Results: Compared to RN, patients with a PN showed a significantly higher 10-year OS (77.0 vs. 63.0%, p = 0.04), CSS (90.6 vs. 71.7%, p = 0.002) and PFS (82.9 vs. 57.4%, p ≤ 0.001). Renal function preservation was better in the PN group (24 months estimated glomerular filtration rate: 68.2 ml/min for PN vs. 40.6 ml/min for RN, p ≤ 0.01) with significantly less new onset chronic kidney diseases. Total complication rate was comparable, whereas PN procedures showed more Clavien-Dindo grade I + II complications, portraying the technical challenge of PN in larger RCCs. Conclusions: Whenever feasible, PN should be considered for renal masses ≥4 cm, as this technique shows better long-term results regarding disease-specific survival and renal function preservation in our study group.

Metformin-Derived Growth Inhibition in Renal Cell Carcinoma Depends on miR-21-Mediated PTEN Expression.

Purpose: Metformin (MF) acts as a tumour-suppressor in renal cell carcinoma (RCC) by inhibiting the AKT/mTOR pathway via AMPK activation. Here, we explore the influence of miR-21 and its target gene PTEN on MF effects in CAKI-1 and CAKI-2 cells. Methods: Proliferation assays (MTS) and qRT-PCR after transient transfection with pre- and anti-miR-21 and MF treatment were conducted. AMPK-dependency was assessed via transfection of siAMPK. The expression of PTEN, AKT and miR-21 after transient pre-miR-21 transfection and MF treatment was analysed. Results: We demonstrate that CAKI-1 cells, which were found to be less sensitive towards MF, showed a significant higher miR-21 and lower PTEN expression than CAKI-2. This was confirmed in a primary RCC collective (n = 28): miR-21 and PTEN expression correlated negatively. MF treatment lowered miR-21 AMPK-dependently and increased PTEN expression in the cell lines. Ectopic miR-21 regulation modulated MF sensitivity. Western blot analysis showed that pre-miR-21 transfection and MF treatment regulated PTEN expression with impact on pAKT levels in the cells. Conclusions: We show that differing MF sensitivity in RCC cells is associated with and mediated through the regulation of miR-21/PTEN expression with an impact on subsequent AKT signalling. This provides imaginable clinical implications regarding MF therapy of RCC patients for the future.

Preoperative C-Reactive Protein Values as a Potential Component in Outcome Prediction Models of Metastasized Renal Cell Carcinoma Patients Receiving Cytoreductive Nephrectomy

Purpose: To validate preoperative C-reactive protein (CRP) levels as a prognostic marker for survival in a metastasized renal cell carcinoma (mRCC) patient cohort receiving cytoreductive nephrectomy (CN). Patients and Methods: By chart review, 146 mRCC patients receiving CN at our tertiary referral centre from 1997 to 2015 were identified retrospectively. All relevant clinicopathological features including laboratory parameters were collected and correlated to overall survival, progression-free survival and cancer-specific survival (CSS). The mean follow-up was 23 months (range 1-168 months). Results: Besides the already established scoring systems like the MSKCC criteria, an elevated preoperative CRP level (≥0.5 mg/dL) was an independent predictor of CSS in our study group including the chosen postoperative adjuvant therapies (TKI vs. immunotherapy vs. others). With regard to morbidity, patients with a good performance status, small tumour size and adequate renal function/haematopoiesis experienced less complication rates, thereby profiting more from CN. Conclusions: Our data provide indication that preoperative CRP levels should be implemented in nomograms regarding the outcome prediction in mRCC to identify candidates likely to profit from CN.

Diagnosis and Clinical Management of Ruptured Ileocecal Pouches for Continent Cutaneous Urinary Diversion

Background and Objectives: The study aimed to report on pouch ruptures in 5 patients with ileocecal reservoirs for continent cutaneous urinary diversion. Patients and Methods: Five male patients aged 48-89 were referred to our department between 2000 and 2016 with a ruptured ileocecal pouch 16-175 months postoperatively. Results: With an incidence of 0.95% in our series (5 ruptures in 529 pouch patients out of a pool of 1,182 radical cystectomies) a rupture of the ileocecal pouch is a rare but severe complication. In all the cases, the rupture was supported by the over-distension of the reservoir, while a traumatic self-catheterization was reported in 2 patients. The rupture occurred on the right lateral wall of the ileocecal pouch in 4 out of 5 cases and led to acute abdominal pain and inflammation. Pouchography was performed in all the patients and revealed a leakage in 4 of them. The rupture was verified intraoperatively in 1 patient. Open surgical exploration, drainage and repair were successfully performed in all 5 cases. Conclusions: Early diagnosis and immediate intervention are mandatory in the cases of pouch rupture to manage this severe complication, which is often related to reduction in patient compliance. Consequently, it is essential to raise awareness of this potentially life-threatening complication in patients with ileocecal pouches.

MP99-16 MIR-221 MODULATES TUMOR GROWTH IN VIVO AND IS A REGULATOR OF TGF-? SIGNALING IN HUMAN PROSTATE CANCER

INTRODUCTION AND OBJECTIVES: Docetaxel (DTX) is one of the primary drugs used for treating castration resistant prostate cancer (CRPC). Unfortunately, over time patients invariably develop resistance to DTX therapy and their disease will continue to progress. The mechanisms by which resistance develops is still incompletely understood. This study seeks to determine the involvement of miRNAs, specifically miR-181a, in DTX resistance in CRPC. METHODS: Total RNA from parental C4-2B prostate cancer cells and DTX resistant C4-2B cells (C4-2B TaxR) was submitted for small RNA deep sequencing. Data was analyzed to ascertain which miRNAs expressions were most altered in C4-2B TaxR cells compared to parental cells. Having identified an increase in miR-181a in resistant cells, its expression was modulated in C4-2B and C4-2B TaxR cells by transfecting them with miR-181a mimics or antisense, respectively. Following transfection, cell number was determined after 48 h with or without DTX. Cross resistance to cabazitaxel induced by miR-181a was also determined. Western blots were used to determine ABCB1 protein expression and rhodamine assays used to assess activity. Phosphop53 expression was assessed by western blot and apoptosis was measured by ELISA in C4-2B TaxR cells with inhibited miR-181a expression with or without DTX. RESULTS: miR-181a is significantly upregulated in C4-2B TaxR cells compared to parental C4-2B cells as analyzed by small RNA sequencing. Overexpression of miR-181a in C4-2B cells confers DTX and cabazitaxel resistance. Knockdown of miR-181a in C4-2B TaxR cells re-sensitizes them to treatment with both DTX and cabazitaxel. miR-181a knockdown alone induced apoptosis in C4-2B TaxR cells which is further enhanced by DTX. We next assessed if miR-181a altered expression or activity of ABCB1, which is overexpressed/active in C4-2B TaxR cells and promotes resistance to DTX by pumping the drug out of cells. We found that miR-181a does not impact ABCB1 expression or activity. Since we previously demonstrated that phosphop53 can modulate DTX sensitivity, we determined if miR-181a can alter p53 expression in C4-2B TaxR cells. Knockdown of miR-181a in C4-2B TaxR cells induced phospho-p53 expression, suggesting that miR-181a induced resistance to DTX is mediated by inhibition of phospho-p53 expression. CONCLUSIONS: Overexpression of mir-181a in C4-2B TaxR cells contributes to their resistance to DTX and inhibition of mir-181a expression can restore treatment response. This is due, in part, to modulation of p53 phosphorylation and induction of apoptosis.