Wareef Kabbani

BAP1 loss defines a new class of renal cell carcinoma

The molecular pathogenesis of renal cell carcinoma (RCC) is poorly understood. Whole-genome and exome sequencing followed by innovative tumorgraft analyses (to accurately determine mutant allele ratios) identified several putative two-hit tumor suppressor genes, including BAP1. The BAP1 protein, a nuclear deubiquitinase, is inactivated in 15% of clear cell RCCs. BAP1 cofractionates with and binds to HCF-1 in tumorgrafts. Mutations disrupting the HCF-1 binding motif impair BAP1-mediated suppression of cell proliferation but not deubiquitination of monoubiquitinated histone 2A lysine 119 (H2AK119ub1). BAP1 loss sensitizes RCC cells in vitro to genotoxic stress. Notably, mutations in BAP1 and PBRM1 anticorrelate in tumors (P = 3 × 10−5), and combined loss of BAP1 and PBRM1 in a few RCCs was associated with rhabdoid features (q = 0.0007). BAP1 and PBRM1 regulate seemingly different gene expression programs, and BAP1 loss was associated with high tumor grade (q = 0.0005). Our results establish the foundation for an integrated pathological and molecular genetic classification of RCC, paving the way for subtype-specific treatments exploiting genetic vulnerabilities.

Role of DAB2IP in modulating epithelial-to-mesenchymal transition and prostate cancer metastasis

A single nucleotide polymorphism in the DAB2IP gene is associated with risk of aggressive prostate cancer (PCa), and loss of DAB2IP expression is frequently detected in metastatic PCa. However, the functional role of DAB2IP in PCa remains unknown. Here, we show that the loss of DAB2IP expression initiates epithelial-to-mesenchymal transition (EMT), which is visualized by repression of E-cadherin and up-regulation of vimentin in both human normal prostate epithelial and prostate carcinoma cells as well as in clinical prostate-cancer specimens. Conversely, restoring DAB2IP in metastatic PCa cells reversed EMT. In DAB2IP knockout mice, prostate epithelial cells exhibited elevated mesenchymal markers, which is characteristic of EMT. Using a human prostate xenograft-mouse model, we observed that knocking down endogenous DAB2IP in human carcinoma cells led to the development of multiple lymph node and distant organ metastases. Moreover, we showed that DAB2IP functions as a scaffold protein in regulating EMT by modulating nuclear β-catenin/T-cell factor activity. These results show the mechanism of DAB2IP in EMT and suggest that assessment of DAB2IP may provide a prognostic biomarker and potential therapeutic target for PCa metastasis.

Impact of Lymph Node Dissection on Cancer Specific Survival in Patients With Upper Tract Urothelial Carcinoma Treated With Radical Nephroureterectomy

PURPOSE We examined the impact of lymphadenectomy on the clinical outcomes of patients with upper tract urothelial cancer treated with radical nephroureterectomy. MATERIALS AND METHODS Data were collected on 1,130 consecutive patients with pT1-4 upper tract urothelial cancer treated with radical nephroureterectomy at 13 centers worldwide. Patients were grouped according to nodal status (pN0 vs pNx vs pN+). The choice to perform lymphadenectomy was determined by the treating surgeon. All pathology slides were reevaluated by dedicated genitourinary pathologists. Univariable and multivariable Cox regression models measured the association of nodal status (pN0 vs pNx vs pN+) with cancer specific survival. RESULTS Overall 412 patients (36.5%) had pN0 disease, 578 had pNx disease (51.1%) and 140 had pN+ disease (12.4%). The 5-year cancer specific survival estimate was lower in patients with pN+ compared to those with pNx disease (35% vs 69%, p <0.001), which in turn was lower than that in those with pN0 disease (69% vs 77%, p = 0.024). In the subgroup of patients with pT1 disease (345) cancer specific survival rates were not different in those with pN0 and pNx. In pT2-4 cases (813) cancer specific survival estimates were lowest in pN+, intermediate in pNx and highest in pN0 (33% vs 58% vs 70%, p = 0.017). When adjusted for the effects of standard clinicopathological features pN+ was an independent predictor of cancer specific survival (p <0.001). pNx was significantly associated with worse prognosis than pN0 in pT2-4 upper tract urothelial cancer only. CONCLUSIONS Nodal status is a significant predictor of cancer specific survival in upper tract urothelial cancer. pNx is significantly associated with a worse prognosis than pN0 in pT2-4 tumors. Patients expected to have pT2-4 disease should undergo lymphadenectomy to improve staging and thereby help guide decision making regarding adjuvant chemotherapy.

Impact of Tumor Location on Prognosis for Patients with Upper Tract Urothelial Carcinoma Managed by Radical Nephroureterectomy

BACKGROUND There is a lack of consensus regarding the prognostic significance of ureteral versus renal pelvic upper tract urothelial carcinoma (UTUC). OBJECTIVE To investigate the association of tumor location on outcomes for UTUC in an international cohort of patients managed by radical nephroureterectomy (RNU). DESIGN, SETTING, AND PARTICIPANTS A retrospective review of institutional databases from 10 institutions worldwide identified patients with UTUC. INTERVENTION The 1249 patients in the study underwent RNU with ipsilateral bladder cuff resection between 1987 and 2007. MEASUREMENTS Data accrued included age, gender, race, surgical approach (open vs laparoscopic), tumor pathology (stage, grade, lymph node status), tumor location, use of perioperative chemotherapy, prior endoscopic therapy, urothelial carcinoma recurrence, and mortality from urothelial carcinoma. Tumor location was divided into two groups (renal pelvis and ureter) based on the location of the dominant tumor. RESULTS AND LIMITATIONS The 5-yr recurrence-free and cancer-specific survival estimates for this cohort were 75% and 78%, respectively. On multivariate analysis, only pathologic tumor (pT) classification (p<0.001), grade (p<0.02), and lymph node status (p<0.001) were associated with disease recurrence and cancer-specific survival. When adjusting for these variables, there was no difference in the probability of disease recurrence (hazard ratio [HR]: 1.22; p=0.133) or cancer death (HR: 1.23; p=0.25) between ureteral and renal pelvic tumors. Adding tumor location to a base prognostic model for disease recurrence and cancer death that included pT stage, tumor grade, and lymph node status only improved the predictive accuracy of this model by 0.1%. This study is limited by biases associated with its retrospective design. CONCLUSIONS There is no difference in outcomes between patients with renal pelvic tumors and with ureteral tumors following nephroureterectomy. These data support the current TNM staging system, whereby renal pelvic and ureteral carcinomas are classified as one integral group of tumors.

Tumour architecture is an independent predictor of outcomes after nephroureterectomy: a multi‐institutional analysis of 1363 patients

To assess whether tumour architecture can help to refine the prognosis of patients treated with nephroureterectomy (NU) for urothelial carcinoma (UC) of the upper urinary tract (UT), as the prognostic value of tumour architecture (papillary vs sessile) in UTUC remains elusive.

A Validated Tumorgraft Model Reveals Activity of Dovitinib Against Renal Cell Carcinoma

Extensively validated tumorgraft model shows activity of investigational agent dovitinib against renal cell carcinoma. Grafting a Better Cancer Model When it comes to predicting drug responsiveness in cancer patients, the standard mouse models (xenografts) get low marks: Drugs that work in these mice are frequently ineffective in humans. Xenograft models are created by injecting human tumor cell lines—which often acquire new mutations in culture—into immunocompromised mice. The resulting tumors are generally different from the original tumor. Tumorgrafts, instead created by implanting fragments of human tumors directly into mice, are generating new excitement among some researchers. Sivanand et al. now describe and validate a tumorgraft model of renal cell carcinoma (RCC) that shows promise for preclinical drug studies. The scientists implanted small fragments of RCC tumor from 94 patients into mice, placing the fragments under the fibrous capsule that surrounds the kidney. Sixteen stable tumor lines—which could be serially passaged to new mice—were ultimately established. Examination by a clinical pathologist revealed that the tumorgrafts were quite similar histologically to the original tumors; gene expression patterns, DNA copy number changes, and most mutations in protein-coding regions were also preserved. In addition, mice bearing tumorgrafts from patients that developed elevated concentrations of serum calcium similarly developed tumor-induced hypercalcemia. Moreover, tumorgraft growth was inhibited by two drugs (sunitinib, approved for treating RCC, and sirolimus, the active metabolite of an approved RCC drug), but did not respond to a lung cancer drug that is inactive against RCC. Finally, dovitinib, an inhibitor of several growth factor receptors that is being studied in clinical trials, suppressed the tumorgrafts more potently than sunitinib or sirolimus, suggesting that dovitinib would be active against RCC in humans. These results apply more broadly: The tumorgrafts should be useful for testing other targeted drugs preclinically—an important need, given that most anticancer drugs that enter clinical trials fail to gain approval. Most anticancer drugs entering clinical trials fail to achieve approval from the U.S. Food and Drug Administration. Drug development is hampered by the lack of preclinical models with therapeutic predictive value. Herein, we report the development and validation of a tumorgraft model of renal cell carcinoma (RCC) and its application to the evaluation of an experimental drug. Tumor samples from 94 patients were implanted in the kidneys of mice without additives or disaggregation. Tumors from 35 of these patients formed tumorgrafts, and 16 stable lines were established. Samples from metastatic sites engrafted at higher frequency than those from primary tumors, and stable engraftment of primary tumors in mice correlated with decreased patient survival. Tumorgrafts retained the histology, gene expression, DNA copy number alterations, and more than 90% of the protein-coding gene mutations of the corresponding tumors. As determined by the induction of hypercalcemia in tumorgraft-bearing mice, tumorgrafts retained the ability to induce paraneoplastic syndromes. In studies simulating drug exposures in patients, RCC tumorgraft growth was inhibited by sunitinib and sirolimus (the active metabolite of temsirolimus in humans), but not by erlotinib, which was used as a control. Dovitinib, a drug in clinical development, showed greater activity than sunitinib and sirolimus. The routine incorporation of models recapitulating the molecular genetics and drug sensitivities of human tumors into preclinical programs has the potential to improve oncology drug development.

Interplay Between pVHL and mTORC1 Pathways in Clear-Cell Renal Cell Carcinoma

mTOR complex 1 (mTORC1) is implicated in cell growth control and is extensively regulated. We previously reported that in response to hypoxia, mTORC1 is inhibited by the protein regulated in development and DNA damage response 1 (REDD1). REDD1 is upregulated by hypoxia-inducible factor (HIF)-1, and forced REDD1 expression is sufficient to inhibit mTORC1. REDD1-induced mTORC1 inhibition is dependent on a protein complex formed by the tuberous sclerosis complex (TSC)1 and 2 (TSC2) proteins. In clear-cell renal cell carcinoma (ccRCC), the von Hippel-Lindau (VHL) gene is frequently inactivated leading to constitutive activation of HIF-2 and/or HIF-1, which may be expected to upregulate REDD1 and inhibit mTORC1. However, mTORC1 is frequently activated in ccRCC, and mTORC1 inhibitors are effective against this tumor type; a paradox herein examined. REDD1 was upregulated in VHL-deficient ccRCC by in silico microarray analyses, as well as by quantitative real-time PCR, Western blot, and immunohistochemistry. Vhl disruption in a mouse model was sufficient to induce Redd1. Using ccRCC-derived cell lines, we show that REDD1 upregulation in tumors is VHL dependent and that both HIF-1 and HIF-2 are, in a cell-type-dependent manner, recruited to, and essential for, REDD1 induction. Interestingly, whereas mTORC1 is responsive to REDD1 in some tumors, strategies have evolved in others, such as mutations disrupting TSC1, to subvert mTORC1 inhibition by REDD1. Sequencing analyses of 77 ccRCCs for mutations in TSC1, TSC2, and REDD1, using PTEN as a reference, implicate the TSC1 gene, and possibly REDD1, as tumor suppressors in sporadic ccRCC. Understanding how ccRCCs become refractory to REDD1-induced mTORC1 inhibition should shed light into the development of ccRCC and may aid in patient selection for molecular-targeted therapies. Mol Cancer Res; 9(9); 1255–65. ©2011 AACR.

Conservative management in selected patients with upper tract urothelial carcinoma compares favourably with early radical surgery

To compare the outcomes of patients treated for upper tract urothelial carcinoma with either immediate nephroureterectomy (NU) or initial endoscopic management.

Absence of Viable Renal Carcinoma in Biopsies Performed More Than 1 Year Following Radio Frequency Ablation Confirms Reliability of Axial Imaging

PURPOSE Radio frequency ablation is an emerging nephron sparing treatment option in select patients with small renal tumors. Some have questioned the completeness of cell death and the reliability of axial imaging for radio frequency ablation followup. We present results in patients with no evidence of radiographic active disease who underwent biopsy more than 1 year following ablation. MATERIALS AND METHODS Patients who had no clinical evidence of disease, defined as absent lesion growth and contrast enhancement on computerized tomography, 1 year or more following radio frequency ablation underwent percutaneous renal biopsy to evaluate cell viability in the ablative zone. A total of 19 patients (20 lesions) were included in the study. Histological comparison of pre-ablation and post-ablation specimens was performed using hematoxylin and eosin staining. RESULTS Pre-ablation biopsies confirmed that 17 of 20 tumors were renal cell carcinoma, while the remaining 3 were oncocytoma. Following ablation at a mean followup of 26.9 months (range 13.1 to 58.0) all 20 lesions were stable in size without evidence of contrast enhancement on computerized tomography. At repeat biopsy all histology specimens showed unequivocal tumor eradication with no evidence of cellular viability. Histological changes beyond 1 year demonstrated coagulative necrosis, hyalinization, inflammatory cell infiltration and residual ghost cells. CONCLUSIONS Pathological examination of radiographically negative lesions biopsied more than 1 year following radio frequency ablation confirmed no evidence of disease in all specimens. Therefore, axial imaging can reliably monitor treatment efficacy in the long term. Chronic changes after radio frequency ablation demonstrate coagulative necrosis and nonviable cells. This suggests an evolution of pathological changes that renders early post-ablative biopsy unreliable.

Impact of Histological Variants on Clinical Outcomes of Patients with Upper Urinary Tract Urothelial Carcinoma

PURPOSE We investigated the clinical and prognostic impact of variant histologies on upper tract urothelial carcinoma outcomes after radical nephroureterectomy. MATERIALS AND METHODS Data on 1,648 patients with upper tract urothelial carcinoma treated with radical nephroureterectomy without preoperative chemotherapy or radiotherapy were reviewed for histological differentiation and variants. We analyzed differences between pure upper tract urothelial carcinoma and upper tract urothelial carcinoma with variant histology, and differences in the histological variants using different stratifications. RESULTS A total of 398 patients (24.2%) had histological upper tract urothelial carcinoma variants. The most common variants were squamous cell and glandular differentiation in 9.9% and 4.4% of cases, respectively. Histological variants were associated with advanced tumor stage, tumor multifocality, sessile tumor architecture, tumor necrosis, lymphovascular invasion and lymph node metastasis compared to pure upper tract urothelial carcinoma (p ≤0.031). On univariable analysis variant histology was associated with disease recurrence (p = 0.002) and cancer specific mortality (p = 0.003). In 174 patients treated with adjuvant chemotherapy there was no difference in disease recurrence or survival between variant histology and pure upper tract urothelial carcinoma (p = 0.42 and 0.59, respectively). On multivariable analysis adjusted for the effects of standard clinicopathological characteristics variant histology was not associated with either end point. CONCLUSIONS Almost 25% of patients with upper tract urothelial carcinoma treated with radical nephroureterectomy harbored histological variants. Variant histology was associated with features of biologically aggressive upper tract urothelial carcinoma. While variant histology is associated with worse outcomes on univariable analysis but this effect did not remain significant on multivariable analysis.