Citations

249 Background: Evaluating tumor specific pathologic and genetic profiles in mCRPC stage is difficult due to the limited availability of mCRPC tissue. We describe findings from a prospective cohort study performed to obtain concomitant histopathology and genetic information in mCRPC. Methods: Patients with mCRPC initiating abiraterone acetate therapy underwent 2 serial (3 months apart) metastatic (met) site needle core biopsies (NCB1/2). Bone lesions were biopsied using 11-13G core needles and 18G core biopsy devices were used for non-osseous masses. Up to 4 cores were obtained at each biopsy with the 1st core (S1) sent for DNA sequencing, the 2nd (S2) for RNA sequencing, and the 3rd/4th (X3, X4) submitted for xenograft implantation. From each, 1-2 mm segments were separated and formalin-fixed for histopathologic examination (HPE). Results: A total of 54 patients, enrolled between June 2013 and July 2014, underwent 94 NCB (54 NCB1, 40 NCB2), rendering a total of 259 samples (94 S1; 75 S2; 59 X3 and 31 X4) of which 85 (32%) were positive (pos) for tumor by HPE. Positivity for tumor in S1, S2, X3, and X4 cores was 42%, 33%, 22%, and 19%, respectively. At least one core pos for met tumor was observed in 62% NCB1 and 52% NCB2 (overall 52/94; 56%). Met sites biopsied include bone (71), lymph nodes (18), liver (3), penile (1) and pelvic (1) soft tissues. HPE revealed met adenocarcinoma in 44/52, and poorly differentiated carcinoma in 8/52. Gleason grade applied to the met ranged from 3+4 to 5+5. 45/85 pos samples (53%) had > 50% tumor cellularity. Pos NCB in bone lesions was observed in 23/71 (32%), compared to 17/23 (73%) of non-bone sites (p=.0004). 85 S1 samples yielded DNA material, of which 66 (77%) had ≥10% tumoral DNA. 24 cases with negative HPE had ≥10% tumoral DNA; 7 cases with pos HPE had <10 tumoral DNA. In all, 76/94 (81%) NCB yielded tumor material either by HPE or DNA analysis. Conclusions: NCB of mCRPC is feasible and provides adequate tissue for pursuing HPE and sequencing studies. HPE of extracted material correlates with DNA sequencing data and provides complementary information on tumor features. Bone lesions yield significantly less tumoral material than non-osseous sites.

190 Background: It is not known if biopsy of CRPC stage metastases alters CTC results. We evaluated pre & post biopsy CTC counts in a prospective cohort undergoing pre-chemotherapy abiraterone acetate/prednisone (AA/P). Methods: CTC enumeration was performed on 7.5mL blood using the FDA cleared immunomagnetic/immunofluorescence assay (CellSearch). Time of blood draw for CTC counts pre/post biopsy was recorded for each biopsy. Biopsies were performed using 11/13 gauge core biopsy device for bone lesions and 18 gauge core needle biopsy device for soft tissue/nodal metastases. All patients (pts) underwent two serial biopsies 3 months apart. Change in CTC counts pre/post biopsy for visits 1 and 2 were evaluated using Wilcoxon signed rank test (significance at p<0.05). Differences in CTC count change (visit1) pre/post biopsy based on metastatic site (skeletal vs. non-skeletal) was compared using Wilcoxon rank-sum test. Results: Median age of the cohort was 74 years (IQR: 68-78); median PSA at V1 was 16.4 ng/ml (IQR: 6.4-87.6); at V2 was 11.5 ng/ml (IQR: 1.8-23.7). Of 59 pts undergoing biopsies 42 were in bone and 17 in nodal/soft tissue masses. At V1, pre/post biopsy CTC counts were measured on 50 and 49 pts, respectively; at V2, pre/post CTC counts were measured on 43 and 36 pts. High volume metastatic disease at V1 was observed in 67.8 % of all pts. Table lists CTC counts and time of collection pre/post biopsy for both visits. Mean change in pre/post biopsy CTC counts for skeletal sites was 0.7 (range: -12 to 64) compared to 12.1 (range: -21 to 13) for non-skeletal sites (p=0.23). Conclusions: An increase in mean CTC counts after biopsy of CRPC metastases was observed. No significant differences in change of CTC counts based on site biopsied (skeletal versus non-skeletal) was noted. Correlation with clinical outcomes is on-going. Clinical trial information: NCT# 01953640. [Table: see text]

174 Background: AA/P is an FDA approved treatment for mCRPC. Since markers of early resistance to AA/P are unknown, we report initial findings of androgen receptor (AR) based associations with short term (12 week) progression on AA/P. Methods: mCRPC stage patients (pts) initiating pre-chemotherapy AA/P underwent metastatic site biopsies at baseline (pre AA/P) and after 12 weeks. Baseline somatic whole exome DNA, tumor gene expression for AR full length (ARFL), AR splice variant 7 (ARV7) and ARV7/ARFL ratios were compared in progessors versus non-progressors. Progression at or within 12 weeks of AA/P therapy was defined as death or disease progression by PCWG2 “composite progression (CP)” and/or “radiographic progression” endpoints. Wilcoxon rank-sum tests were used to test for differences in the two groups for comparing ARFL, ARV7 expressions and ARV7/ARFL ratios and chi square tests were used for differences in copy number variation. Results: Between 1/2013 and 6/2014, 59 pts were enrolled of which 44 have disease assessment data at the12-week time point. CP was observed in 17/44 patients. DNA seq and clinical data was available for 42/44 pts. Using radiographic progression at 12 weeks, AR Amplification/Gain was observed in 20/26 non-progressors (13 with Amplification) and in 9/16 progressors (P-value = 0.19; OR 2.5). ARFL and ARV7 gene expressions in both groups is provided in table. Conclusions: A trend towards higher ARV7/ARFL gene expression ratio in metastases was observed with early progression on AA/P. AR gain/amplification is observed less often in pts with early progression. Validation of these findings is on-going in this prospective trial. Clinical trial information: NCT# 01953640. [Table: see text]

624 Background: The risk of intravenous contrast induced nephropathy (CIN) is not well described in post-nephrectomy or metastatic kidney cancer. Patients with nephrectomies and tumors of the kidney frequently have CKD and often require serial contrast imaging placing them at risk for CIN. Methods: This is a retrospective review of 292 patients metastatic RCC and/or with partial or radical nephrectomies (PN or RN) for kidney tumors at Mayo Clinic Arizona or Florida from 2010 through 2014. Results: We found 207 patients received at least one contrast scan, of whom 99 had metastatic RCC, 104 had local RCC and 4 had oncocytoma. At baseline (pre-nephrectomy) 41% (46/113) and 15% (11/76) of RN and PN respectively had CKD stages 3-5 and with at least 3 months follow up after both nephrectomy and contrast exposure 61% (68/113) and 33% (25/76) RN and PN developed CKD stages 3-5 respectively. The median contrast exposure scans were 4 (range 1-30 scans) with a median follow up of 26 months (range 1-96 months). In all patients with at least one contrast exposure, the median change in creatinine and GFR from baseline was 0.2 mg/dL and 8 ml/min respectively. Excluding those with bilateral nephrectomy there were 8 (8/207 = 4%) CIN events, 6/113 had a radical nephrectomy and 2/76 with 1 partial nephrectomy and 1 aborted nephrectomy (P value 0.37). Of these patients 5 (5/99 = 5%) had metastatic RCC and 3 (3/104 = 3%) local RCC. The median contrast exposure scans for patients with CIN were 8 (range 3-12) and median follow up was 31 months (range 4-47 months). Three patients all with metastatic RCC developed acute kidney injury from CIN requiring dialysis and died of complications in part related to CIN during that hospital stay or soon after. Two other patients developed CKD stage III after CIN events and 3 patients (including the one with a partial nephrectomy) showed no significant change in GFR after CIN. Conclusions: In this retrospective analysis, CIN after nephrectomy or metastatic RCC contributed to acute renal failure with 3 deaths and 2 patients developing CKD stage III. Further analysis is required to determine what risk factors for CIN in this population.

616 Background: Polybromo-1 (PBRM1) and BRCA1 associated protein-1 (BAP1) are genes commonly mutated in clear cell RCC (ccRCC) and have been associated with clinical outcome. This work aims to evaluate the impact of PBRM1 and BAP1 expression by IHC in mRCC patients treated with VEGF-TT. Methods: PBRM1 and BAP1 expression was evaluated by IHC in a TMA including 146 mRCC patients. PBRM1 and BAP1 IHC scores were dichotomized as a binary variable: negative (-) or positive (+) (weak positivity was excluded). The associations of PBRM1 or BAP1 expression with baseline clinico-pathological characteristics were evaluated, as well as with overall survival (OS) and time to treatment failure (TTF) usingCox proportional hazards models. Results: Out of 146 patients, 116 and 109 samples had available results for PBRM1 and BAP1 staining, respectively. Overall, 90% (n = 131) patients had ccRCC. 70/116 samples (60%) were PBRM1- and 26/109 patients (24%) were BAP1-. Only 12% (n = 13) of patients had simultaneous negative PBRM1 and BAP1. While there was no association between PBRM1 expression status and clinical factors, BAP1- samples were associated with poor IMDC prognostic risk score (p = 0.004) and higher Fuhrman grade (p = 0.012). PBRM1+ patients showed a trend towards an increased risk of death and a shorter TTF compared to PBRM1- patients (OS: HR = 1.38, 95%CI: 0.92-2.07, p = 0.1; TTF: HR = 1.39, 95%CI: 0.94-2.06, p = 0.1). BAP1 expression was not independently associated with OS or TTF. Conclusions: Loss of PBRM1, but not BAP1 expression showed a trend towards longer TTF and OS in mRCC patients treated with VEGF-TT.

572 Background: Renal medullary carcinoma (RMC) is an aggressive malignancy affecting predominantly young African Americans with sickle cell trait (SCT) or disease (SCD), while a pathologically similar collecting duct carcinoma (CDC) affects patients without sickle cell trait. Clinical responses to chemotherapy and IL-2 in RMC/CDC are poor and novel therapies are needed. Methods: 9 patients with RMC (ages 13-58 y. o., all male) and 15 patients (ages 26-74 y. o., M:F = 13:2) with collecting duct carcinoma (CDC) were studied. Expression of PD-L1 was evaluated with 2 monoclonal antibodies (SP142 and SP263) and tumor infiltrating lymphocytes (TIL) were evaluated for PD1 expression (MRQ-22 antibody) using immunohistochemistry (IHC). Additional studies included ALK protein expression (D5F3 antibody), gene translocation (break apart FISH), next generation sequencing (NGS), and microsatellite instability (MSI). Results: Cancer cell PD-L1 expression above the threshold ( ≥ 2+, ≥ 5%) was seen in 7/9 RMC and 5/13 CDC cases. Concordance between 2 PD-L1 antibodies was 94.4%. PD-1+ TIL were absent in 6/18 cases and variably present in 12/18 cases (from 1 to > 15 TIL/40x power field). No MSI was detected in any of the cases tested (0/6). No case expressed ALK protein, but one case of CDC showed ALK gene re-arrangement. Mutations were identified in SMARCB1, FH, TP53 (3x), ATM, BRCA2, CHEK2 (2x), NF2 (3x), SETD2, and CDKN2A. No mutations in VHL or KDR were detected. One patient with RMC (and SCT) achieved complete clinical remission after treatment with bevacizumab plus paclitaxel. Conclusions: RMC and CDC strongly express PD-L1 in the majority of cases (12/22), suggesting that these patients may benefit from targeting the PD-L1/PD1 interaction. The absence of MSI in these cancers indicates a different mechanism of PD-L1 upregulation from colorectal carcinomas. Consistent with our previous study that showed frequent activation of (pseudo)hypoxia-induced pathways in RMCs (Human Pathology 2011;42:1979), we describe a case of RMC successfully treated with anti-VEGF therapy.

570 Background: Vascular endothelial growth factor- (VEGF-) and mammalian target of rapamycin- (mTOR-) directed therapies represent a standard of care in metastatic renal cell carcinoma (mRCC). However, these agents are not employed based on an assessment of predictive biomarkers such as genomic alterations (GA). We sought to determine if an association exists between GA detected by comprehensive genomic profiling (CGP) and the response to VEGFR and mTOR pathway targeted therapies in a cohort of mRCC treated in a clinical practice setting. Methods: The results of CGP performed in the course of clinical care on 31 consecutive mRCC obtained from patients who had received VEGFR- and/or mTOR-inhibitors were reviewed. Duration of treatment (DOT), extent and duration of clinical response was obtained from review of medical records. All classes of genomic alterations - base substitutions, short insertions, deletions, gene fusions, rearrangements and copy number - were assessed via CGP. Descriptive statistics were used to determine the frequency of GAs in groups segregated by the DOT with VEGF-directed agents. Results: The most common GAs detected in this series were in VHL (70%), PBRM1 (48%), SETD2 (32%), TSC1 (29%), MLL (19%), TERT (16%), ARID1B (16%) and KDM5C (16%). Across 61 administrations of VEGF-directed therapy in 27 patients, exceptional responses (DOT > 21 months) were more frequent amongst patients with GAs in KDM5C, PBRM1, and VHL. Conversely, these patients also featured a lower frequency of GA associated with response to mTOR-directed therapy, such as TSC1. Conclusions: Multiple GAs are more prevalent in exceptional responders to VEGF-directed therapy. Prospective validation of these findings may lead to use of CGP to optimize therapeutic selection.

536 Background: DNA methylation is a heritable covalent modification that is developmentally regulated and is critical in tissue-type definition. Although genotype-phenotype correlations have been described for different subtypes of renal cell carcinoma (RCC), it is unknown if DNA methylation profiles correlate with morphological or ontology based phenotypes. Here we test the hypothesis that DNA methylation signatures can discriminate between putative precursor cells in the nephron. Methods: We performed deep profiling of DNA methylation in diverse histopathological RCC subtypes and validated DNA methylation and transcriptome signatures in The Cancer Genome Atlas Clear Cell and Chromophobe Renal Cell Carcinoma Datasets. Results: Our data provide the first mapping of methylome epi-signature and indicates that RCC subtypes can be grouped into two major epi-clusters: C1 which encompasses clear cell RCC, papillary RCC, mucinous and spindle cell carcinomas and translocation RCC; C2 which comprises oncocytoma and chromophobe RCC. Interestingly, C1 epi-cluster displayed three fold more hypermethylation as compared to C2 epi-cluster. Of note, differentially methylated regions between C1 and C2 epi-clusters occur in gene bodies and intergenic regions, instead of gene promoters. Transcriptome analysis of C1 epi-cluster suggests a functional convergence on Polycomb targets, whereas C2 epi-cluster displays DNA methylation defects. Furthermore, we find that our epigenetic ontogeny signature is associated with worse outcomes of patients with clear-cell RCC. Conclusions: Taken together, our data defines the epi-clusters that can discriminate between distinct RCC subtypes and for the first time, to our knowledge, define the epigenetic basis for proximal versus distal tubule derived kidney tumors.

501 Background: Reports have demonstrated an inverse relationship between suppression of immune surveillance mechanisms and activation of the vascular endothelial growth factor receptor (VEGFR) pathway suggesting that T cell repertoires may impact response to VEGFR blockade. We evaluated the association between clinical outcomes and T cell repertoire in metastatic RCC patients receiving a front-line anti-VEGFR, pazopanib. Methods: Pre-treatment RCC tumors were analyzed from VEG105192, a phase III study of mRCC patients randomized (2:1) to pazopanib (paz) 800 mg daily vs placebo (pbo) for TCR gamma (TCRG) and TCR beta (TCRB) CDR3 regions. Using the Adaptive Biotechnologies immunoSEQ Assay, we assessed TCR clonality, a measure of total repertoire represented by expanded clones, and entropy, a measure of evenness and diversity. PD-L1 was evaluated by immunohistochemistry (IHC) H-Scores. The goal of the study was to determine if the repertoire of T cell clones was associated with progression-free survival as a clinical endpoint. Results: In the cohort with available tissue, the median PFS was 10.8 and 5.5 months (mos) for paz and pbo, respectively. TCRB (n = 114) and TCRG (n = 43 pbo, 109 paz) clonality ranged from 0-0.31 and 0-0.98, and entropy from 1-12.1 and 0-10.37, respectively. TCRB and TCRG entropy were highly correlated (Spearman’s R = 0.92, n = 114). Samples from the pbo-treated group with higher TCRG entropy, defined as the top 25th percentile, were associated with an improved median PFS (12.8 months) when compared to the lower 75th percentile (3.1 months, P = 0.023); similar trends were seen for TCRB entropy. Neither entropy nor clonality was associated with maximal reduction in tumor volume in the paz-treated group. PD-L1 H-scores were not associated with entropy or clonality (P > 0.05). Conclusions: Our data suggests that RCC samples with higher entropy are associated with a favorable prognosis. Identification of tumors with restricted TCRB/G chain usage and less diverse repertoire, as represented by lower entropy and higher clonality, may impact responses to VEGFR blockade and requires further study. Clinical trial information: NCT00334282.

237 Background: AA/P is an approved treatment for mCRPC but there are no known predictive markers of response or resistance. We conducted a prospective trial to evaluate if Androgen Receptor (AR) & AR-variant (ARV) expression in tissue metastases can predict resistance to AA/P. Methods: mCRPC stage patients (pts) initiating pre-chemo AA/P underwent metastatic site biopsies prior to (pre-AA/P) and after 12 weeks of treatment. Composite progression at 12 weeks, (primary endpoint) was evaluated with PSA, RECIST, bone scan and symptoms (per PCWG2). mRNA expressions of pre-AA/P ARFL, ARV3, ARV7, ARV9, ARV23, ARV45, four cell cycle division genes, Chromogranin-A (CHGA) together with PSA/testosterone levels, Gleason Score (GS) at initial diagnosis; high versus low volume disease; time from starting hormone therapy to mCRPC stage and serum CHGA levels were evaluated using a logistic regression model for predicting resistance at 12 weeks of therapy. A final multivariate model fitted only those factors thought to be clinically relevant or with an entry threshold of p ≤ 0.3 in univariate analysis. Results: Between 6/2013 & 3/2015, 82 pts were enrolled of which 52 had complete mRNA expression & disease assessment data at the12-week time point for analysis. Median age of the cohort was 72.5 yrs (IQR: 68.5-78); median pre-AA/P PSA was 18 ng/ml (IQR: 8.1- 46.6); GS distribution at initial diagnosis for GS 2-6; 7; 8-10 was 11; 14; 27 respectively. Progression was observed in 21/52 pts after 12 weeks. At the univariate level elevated pre-AA/P expression of ARV3 (p = 0.08), ARV7 (p = 0.26), ARV9 (p = 0.04), and cell division cycle gene CDC45 (p = 0.19) along with GS at diagnosis (p = 0.29) met the threshold for inclusion into multivariate analysis. Elevated expression of pre-therapy ARV9 in metastases alone was associated with progression at 12 weeks (OR: 3.9; CI 1.07 – 14.16; C-Index: 0.63). The 12-week biopsy of pts with progression had increased ARV9 mRNA expression compared to pts responding at 12 weeks (p = 0.14). Conclusions: Increased ARV9 mRNA expression in metastases is associated with early resistance to AA/P. This observation will need further validation in comparable datasets. Clinical trial information: NCT #0195364.