Costello, Brian A.

Abstract Background: Endemic nasopharyngeal carcinoma (NPC) refers to non-keratinizing (NK) subtypes harboring Epstein Barr virus (EBV) that frequently express programmed death-ligand 1 (PD-L1). We recently reported ≥30% of NPC harbor MHC class 1 gene alterations in a whole genome study. Method: We investigated the activity of nivolumab (NIVO) & relationship with PD-L1 & HLA expression (exp) in tumor cells (TC) & tumor infiltrating cells (TIL). Eligible patient (pt)s had to fail ≥ 1 prior line of platinum-based chemo. NIVO (3mg/kg IV, q2 weeks) was given until disease progression (PD). Archived tumors were analyzed for PD-L1 (DAKO) & HLA mutations (indicated by loss of HLA-A &/or B exp). Result: A total of 45 pts were enrolled across 11 sites from Oct 2015 to June 2016. Overall, 43 and 44 pts were evaluable respectively for response rate (RR, RECIST) & adverse events (AE). The median age was 57 years, 77% pts were males & 84% were Asians. The median number of prior chemo was 3 (range 1-9 lines). Of the 43 evaluable pts, there were 8 confirmed (19%, 95% CI: 8-33%) & 1 unconfirmed partial response (PR), 17 PD (40%), 14 stable disease (SD, 33%) & 3 pts were not assessed. One pt (MD015-027) had an unconfirmed clinical CR in an occipital metastasis (met). Pts received a median of 3 cycles of NIVO (range 1 - 14). Median overall survival has not been reached yet. Of the 44 pts evaluable for AE, 8 (18.2%) had grade 3 or higher treatment-related AEs & 1 pt died of sepsis. The most common grade 3 or higher AEs were increase in alanine/aspartate aminotransferase (n=3), & 1 pt respectively for hyponatremia, neutropenia, fatigue & diarrhea. Of the 21 tumor samples analyzed, 11/21 (52%) had >1% PD-L1 expressed mainly in TC. Table 1 outlines relationship between RR & PD-L1 exp. All pts with PR had >5% PD-L1 exp & one pt (34003-022) with CR (nasopharynx) & PR (lung mets) had the highest exp (80%). Majority of pts with PD had <1% PD-L1 exp tumors. One primary progressor (34003-032) had a PD-L1 +ve tumor harboring a complete loss of HLA-B signal (TC), but intact signal in TILs & stromal cells. Conclusion: NIVO is active in this heavily pre-treated group of pts with NK-NPC and longer follow-up is needed for survival endpoints. Preliminary result suggests PD-L1 exp may predict benefit from NIVO. The analytical result of all 45 tumors will be presented. Table 1.PD-L1 exp and RECIST response in 21 ptsPD-L1%espRR%PRSDPD0-11<1%-265%24-10%--120%-1-30%11-80%1--Total498 Citation Format: Brigette B. Ma, Boon Cher Goh, Wan T. Lim, Kwok W. Lo, Edwin P. Hui, Jonathan W. Riess, Mark Agulnik, Alex Y. Chang, Julie A. Kish, Dean W. Lim, Douglas R. Adkins, Kevin J. Cullen, Barbara J. Gitlitz, Nathan R. Foster, Adam M. Pettinger, Sanna Mckinzie, Ka F. To, Brian Costello, Howard Streicher, Anthony T. Chan. Multicenter phase II study of nivolumab in previously treated patients with recurrent and metastatic non-keratinizing nasopharyngeal carcinoma - Mayo clinic Phase 2 Consortium P2C-MN026, NCI9742, NCT02339558 [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 CT076. doi:10.1158/1538-7445.AM2017-CT076

Abstract Purpose: Androgen receptor (AR) variant AR-V7 is a ligand-independent transcription factor that promotes prostate cancer resistance to AR-targeted therapies. Accordingly, efforts are under way to develop strategies for monitoring and inhibiting AR-V7 in castration-resistant prostate cancer (CRPC). The purpose of this study was to understand whether other AR variants may be coexpressed with AR-V7 and promote resistance to AR-targeted therapies. Experimental Design: We utilized complementary short- and long-read sequencing of intact AR mRNA isoforms to characterize AR expression in CRPC models. Coexpression of AR-V7 and AR-V9 mRNA in CRPC metastases and circulating tumor cells was assessed by RNA-seq and RT-PCR, respectively. Expression of AR-V9 protein in CRPC models was evaluated with polyclonal antisera. Multivariate analysis was performed to test whether AR variant mRNA expression in metastatic tissues was associated with a 12-week progression-free survival endpoint in a prospective clinical trial of 78 CRPC-stage patients initiating therapy with the androgen synthesis inhibitor, abiraterone acetate. Results: AR-V9 was frequently coexpressed with AR-V7. Both AR variant species were found to share a common 3′ terminal cryptic exon, which rendered AR-V9 susceptible to experimental manipulations that were previously thought to target AR-V7 uniquely. AR-V9 promoted ligand-independent growth of prostate cancer cells. High AR-V9 mRNA expression in CRPC metastases was predictive of primary resistance to abiraterone acetate (HR = 4.0; 95% confidence interval, 1.31–12.2; P = 0.02). Conclusions: AR-V9 may be an important component of therapeutic resistance in CRPC. Clin Cancer Res; 23(16); 4704–15. ©2017 AACR.

522 Background: In the METEOR study (NCT01865747), cabo demonstrated improved progression-free survival (median 7.4 vs. 3.8 mo; HR 0.58, 95% CI 0.45–0.74; p<0.0001), OS (median 21.4 vs. 16.5 mo; HR 0.66, 95% CI 0.53-0.83, p=0.0003), and objective response rate (17% vs. 3%; p<0.0001) compared with eve in patients (pts) with advanced RCC who had received prior VEGFR TKI therapy (Choueiri NEJM 2015, Lancet Oncol 2016). Here we evaluate the impact of changes in target lesion size from baseline on OS. Methods: 658 pts were randomized 1:1 to receive cabo (60 mg qd) or eve (10 mg qd). Stratification factors were MSKCC risk group and number of prior VEGFR TKIs. Target lesion size was assessed per independent radiology review by CT/MRI scans at baseline, every 8 weeks for the first 12 months, and every 12 weeks thereafter. Three subgroups were defined by best change in target lesion size from baseline: decrease ≥30%, decrease <30%, and any increase. Results: The rate of target lesion regression was higher in the cabo arm (75%) compared with the eve arm (48%). A higher fraction of pts had a decrease ≥30% in target lesion size in the cabo arm, while a higher fraction of pts had an increase in target lesion size in the eve arm (Table). Medians for OS with cabo were not estimable (NE) (95% CI, NE‒NE), 20.8 mo (95% CI, 18.1‒NE), and 11.1 mo (95% CI, 7.6‒15.2) for the ≥30% decrease, <30% decrease, and any increase subgroups, respectively. Medians for OS with eve were NE (95% CI, 19.3‒NE), 18.0 mo (95% CI, 15.9‒20.4), and 14.0 mo (95% CI, 10.5‒16.3) for the ≥30% decrease, <30% decrease, and any increase subgroups, respectively. Median duration of follow-up for OS was 18.7 mo (IQR 16.1–21.1) for cabo and 18.8 mo (16.0–21.2) for eve. A higher proportion of pts received subsequent anticancer therapy in the any increase subgroup compared with the other subgroups. Conclusions: Cabo demonstrated a higher rate of tumor target lesion regression than eve, and greater target lesion regression was associated with improved OS in pts with advanced RCC. Clinical trial information: NCT01865747. [Table: see text]

500 Background: The Memorial Sloan Kettering Cancer Center (MSKCC) prognostic score is based on clinical parameters and has several limitations. We analyzed whole blood mRNA expression in mCCRCC patients (pts) and compared it to MSKCC for predicting overall survival (OS). Methods: A prospective collection of whole blood in PAXgene RNA tubes from mCCRCC pts was performed between 2011 and 2015 with uniform processing. A discovery set (DS) of 19 randomly selected pt samples was used to generate whole transcriptome RNA sequencing and signatures describing differential gene expression patterns associated with OS. We calculated the fragment per kilobase of transcript per million (FPKM) of each transcript and gene to identify correlations between the differentially expressed genes and MSKCC score. Candidate genes were selected based on statistical significance (p<0.05) and associations with OS. In an independent validation set (VS) of 47 pts with mCCRCC, we used the nCounter Analysis System (NanoString Technologies, Seattle, WA, USA) to quantify gene transcript expression selected from the DS. Cox regression and Kaplan-Meier analysis were used for association of candidate mRNAs in the VS with OS (time of metastatic recurrence to death or last follow-up). We compared our gene signature to the MSKCC prognostic score for poor versus good survival. Results: In the DS, at a median follow-up of 4.13 years (yrs) (range: 1.3-4.5), 11 patients had died. We identified eighteen genes in the DS with statistically significant differential gene expression patterns and ability to discriminate patient OS. In the VS at a median follow-up of 4.9 yrs (range: 0.1-11.3), twenty-five patients had died. We confirmed two of the eighteen selected genes that had strong prognostic significance: BAG1 [hazard ratio (HR) 0.31, p=0.007] and NOP56 [HR 0.28, p=0.004]. Comparing OS between good and poor outcome groups for these 2 scores, our two-gene panel had higher prognostic ability (HR 20.07, p <0.0001) than the MSKCC prognostic score (HR 3.19, p 0.04). Conclusions: Prognostic value of using whole blood mRNA gene profiling in mCCRCC is feasible and should be prospectively confirmed in larger studies.

456 Background: Renal medullary carcinoma (RMC) is a rare, aggressive malignancy for which relatively limited characterization exists to date. We evaluated clinicopathologic features, treatment patterns, and variables associated with outcomes for patients with RMC. Methods: We reviewed the National Cancer Database to identify patients diagnosed with RMC between 1998-2012. Overall survival (OS) was estimated using the Kaplan-Meier method. Clinicopathologic features associated with all-cause mortality (ACM) were assessed using Cox regression analysis. Results: We identified 153 patients with RMC, comprising approximately 0.04% of renal malignancies during this time period. Median age at diagnosis for RMC was 24 years (IQR 20, 31). The majority of RMC patients were black (135; 88%), male (108; 71%), and presented with unilateral, right-sided tumors (101; 66%). Notably, nearly half (72; 48.9%) presented with metastatic disease. A total of 92 (64.3%) patients underwent radical nephrectomy (RN), and 2 (1.3%) were treated with partial nephrectomy. Pathologic stage at nephrectomy was ≤pT2 in 30 patients (32.6%), pT3 in 43 (46.7%), pT4 in 7 (7.6%), and N+ in 50 (55.6%). Of the patients who underwent RN, 60 (65.2%) received multimodal therapy (MMT), including radiation (3; 3.3%), systemic therapy (49; 53.3%), and radiation + systemic therapy (8; 8.7%). Of the 59 patients who did not undergo surgical resection, the majority (46; 77.8%) presented with M1 disease. Median OS was 7.8 months for the entire RMC cohort, with 1- and 3-year OS of 34% and 11%, respectively. Notably, median OS for patients presenting with M1 and M0 disease was 5.2 months versus 11.2 months, respectively (p< 0.01). On multivariable analysis, treatment with RN (HR 0.40; p=0.003) or RN+MMT (HR 0.44; p<0.001) were associated with decreased ACM, whereas the presence of metastatic disease at diagnosis remained associated with an increased risk of ACM (HR 1.74; p=0.02). Conclusions: The prognosis for patients with RMC is dismal, with a median OS under 8 months. Further studies, including the development of novel therapies, are needed to establish the optimal multimodal management approach for these patients.

402 Background: AGS-003 is an autologous tumor RNA-loaded dendritic cell-based immunotherapy being tested in advanced renal cell carcinoma (RCC) patients. The immunologic specificity for the patient’s own tumor is achieved using amplified tumor RNA electroporated into monocyte derived dendritic cells. To produce AGS-003 for RCC patients the RNA is amplified from a 100 mg primary tumor sample obtained via nephrectomy. In this non treatment study we evaluated the feasibility of RNA amplification from MIBC tissue acquired by transurethral resection of bladder tumor (TURBT). Methods: MIBC tissue was obtained via TURBT. Following draining of the irrigant used during the TURBT procedure, tissue was placed into an RNA preservative solution to prevent RNA degradation until processing. Methods developed for the amplification of RCC tumor RNA and RNA quality testing were applied to the RNA extracted from the MIBC specimens. Results: This work demonstrated that the methods developed for the amplification and testing of RNA from RCC can be successfully employed for the amplification of RNA from MIBC specimens collected by TURBT. Results demonstrated that the total RNA yields obtained from bladder tissue exceed that of similar masses of primary RCC tumors. This finding enabled the reduction in the amount of starting material from 100 mg to 50 mg of bladder tissue. The amount of amplified RNA produced from the lower bladder cancer masses were sufficient to support the production of immunotherapy at full scale (17 doses average). Conclusions: These data demonstrate the feasibility of RNA extraction and amplification from muscle invasive bladder cancer tissue and supports our planned phase II clinical study. [Table: see text]

355 Background: While neoadjuvant chemotherapy (NAC) prior to radical cystectomy (RC) improves survival compared to RC alone for urothelial carcinoma of the bladder (UCB), the bulk of this survival benefit has been attributed to patients who achieve ypT0 status at RC. The implications of having residual UCB (rUCB) at RC after NAC are less clear. As such, we evaluated whether the outcomes for patients with rUCB after NAC differ from stage-matched RC patients who did not receive NAC. Methods: Patients undergoing RC for UCB between 1981-2010 at Mayo Clinic were identified. All RC pathology was re-reviewed by a single genitourinary pathologist. Patients who received NAC were matched 1:2 to patients not exposed to NAC based on pT and pN-stage, margin status, and year of RC. Kaplan Meier and Cox regression analyses were used to evaluate the associations between NAC and cancer-specific (CSS) and overall survival (OS), stratified by presence of rUCB (i.e. (y)pT0N0 and non-(y)pT0N0). Results: We matched 111 patients who underwent NAC + RC to 222 RC-alone patients. Median age was 68 years (IQR 60,74); 59 (18%) were female. Median follow-up among survivors was 7.2 years (IQR 6,16). A total of 248 patients died; 148 died from UCB. In patients without rUCB at RC, there were no differences in 5-yr CSS (86% vs. 90%, p=0.85) or OS (82% vs. 84%, p=0.46) between patients who did and did not receive NAC. Moreover, on multivariable analysis, NAC exposure was not associated with CSS (HR=1.0; 95%CI 0.3-3.1; p=0.9) or OS (HR=0.9; 95%CI 0.4-1.9; p=0.8) in this subgroup. Among patients with rUCB, receipt of NAC was associated with significantly worse 5-yr CSS (32% vs. 56%, p<0.001) and OS (25% vs. 48%, p<0.001). NAC exposure remained independently associated with worse CSS (HR=2.2; 95%CI 1.6-3.1; p<0.001) and OS (HR=2.0; 95%CI 1.5-2.7; p<0.001) among these patients. Conclusions: While patients who achieve a complete response to NAC have excellent survival outcomes, patients with residual UCB at RC after NAC have a worse prognosis compared to stage-matched RC patients not exposed to NAC. Such patients should be considered for enrolment in novel adjuvant therapy trials.

175 Background: Genome and transcriptome aberrations associated with primary resistance to abiraterone acetate/prednisone (AA/P) in mCRPC are not known. In a prospective trial (NCT#01953640) we assessed whole-exome and RNA-seq based aberrations in metastases of CRPC stage patients (pts) for identifying markers associated with primary resistance to AA/P. Methods: Whole-exome and RNA-seq of biopsies from metastases was performed followed by analyses for association between genomic aberrations & primary resistance. Primary resistance was defined by progression on AA/P after 12-weeks of therapy(non-responders) using PSA, RECIST, bone scan and symptom criteria (per PCWG2). Gene network analysis was performed in genes mutated more frequently in non-responders, and also in genes that were differentially expressed between non-responders and responders and a “risk ratio” (RR) was calculated thereof. Results: Between 6/2013 & 8/2015, 92 pts were enrolled of which 82 had complete whole-exome, RNA-seq and 12-week outcome data available for analysis. Median age was 72.5 yrs (IQR: 68.5-78); median PSA-18 ng/ml (IQR: 8.1- 46.6). At 12-weeks 33/82 had progressed. Using the RR of 2 as threshold, we identified 113 and 292 genes that were more frequently mutated in non-responders & responders respectively. Among the 113 genes, OBSCN, ADAM21, LPHN3, DOCK10 ( P = 0.08, RR= inf) & USP42 ( P = 0.16, RR = 5.71) were the top candidates.Gene network analysis revealed that in non-responders, genes involved in the Wnt/β-catenin pathway were frequently mutated and negative regulators of Wnt pathway ( DKK4, SFRP2 & LRP6) were also frequently deleted. Gene expression analyses revealed the expression levels of Wnt/β-catenin pathway inhibitors were significantly reduced while expression levels of cell cycle regulatory genes were significantly increased in non-responders. Conclusions: In this study we observed Wnt/β-catenin pathway activation to be associated with primary AA/P resistance. This finding offers a potential for the development of predictive biomarkers and modulation of targeted pathways to overcome AA/P resistance. Clinical trial information: NCT# 01953640.

503 Background: We evaluated temporal patterns in the utilization of systemic therapy among patients undergoing cytoreductive nephrectomy (CN) for metastatic Renal Cell Carcinoma (mRCC) from a large national cancer registry and assessed patient characteristics associated with receipt of systemic treatment. Methods: We reviewed the National Cancer Database to identify patients with stage IV RCC who underwent CN between 1998-2010. Systemic therapy was defined as any treatment with immunotherapy and/or chemotherapy (including targeted agents). We evaluated the association between clinicopathologic features and receipt of systemic therapy using multivariable logistic regression with generalized estimating equations, and assessed the interaction of treatment with time, stratified as immunotherapy (1998-2004) versus targeted-therapy (2005-2010) eras. Results: Of 22,409 patients with mRCC undergoing CN, 8,830 (39%) received systemic therapy. Receipt of systemic therapy increased from 32% in 1998 to 49% in 2010 (p<0.001), largely due to increased utilization of chemotherapy (13.9% vs. 46.7%; p<0.001). Following adjustment, increasing patient age (51-60 years: OR 0.82 [CI 0.73-0.92]; 61-70 years: OR 0.67 [CI 0.59-0.76]; ≥71 years: OR 0.36 [CI 0.31-0.43]), as well as coverage with Medicaid (OR 0.61 [CI 0.5-0.74]), Medicare (OR 0.70 [CI 0.62-0.79]), or no insurance (OR 0.75 [CI 0.63-0.91]) were associated with decreased utilization of systemic therapy. Although use of systemic therapy in the elderly (≥71 years) and in patients with Medicare/Medicaid remained lower throughout the study period, each of these cohorts was significantly more likely to receive systemic treatment in the targeted versus immunotherapy era (all p values <0.05). Conclusions: Utilization of systemic therapy among patients undergoing CN has increased over time, coinciding with the introduction of targeted therapies. Nevertheless, still less than half of such patients receive systemic treatment. While the etiology for lack of treatment is likely multifactorial, the potential health policy implications of continued disparities in care warrant further investigation.

364 Background: Flavopiridol + FOLFOX showed activity in refractory GCT pts in a phase I trial (Rathkopf, Clin Cancer Res, 2009). This phase II study assessed the efficacy of this regimen in refractory GCT and the necessity of including 5-FU/LV. Methods: Previously treated pts with progressive GCT were eligible if they had received or were not candidates for high-dose chemotherapy (HDCT). Pts on Arm A received flavopiridol 70mg/m2 plus oxaliplatin 85mg/m2. Arm B (flavopiridol + FOLFOX) tested identical doses of flavopiridol and oxaliplatin plus 5-FU (400mg/m2 bolus, then 1800mg/m2 over 48 hours) and LV 400mg/m2. Treatment was every 2 weeks in 6-week cycles. The primary endpoint was response rate (RR) by RECIST. An identical Simon 2-stage design was used for each arm to differentiate between a RR ≥40% vs. ≤20%, with arm B opening only if arm A was ineffective. With ≥3 responses among the first 12 pts, another 13 pts would be enrolled with responses in ≥8/25 pts needed to show efficacy. Tumor biopsies pre-, during, and post-treatment were assessed by IHC for p53, p21, and cleaved caspase-3. Results: Of 36 pts (7 arm A, 29 arm B), 33 had nonseminoma. Primary site was testis in 27 and mediastinum in 7; 22 pts had received prior HDCT and 13 had LR (>2 years), including 2 on arm A and 11 on arm B. Arm A closed early after 0/7 pts responded (2 SD). Of 25 evaluable pts on arm B, 6 achieved a PR, 9 had SD, and 10 had PD. Notably, 5/10 evaluable LR pts on Arm B had a PR, including 1 pathologic CR, 1 PR-negative markers who received radiation (RT) to a residual bone metastasis, and 1 PR-positive markers who received RT to a residual nodal mass. These 3 pts remain disease-free ≥19 months (m) post-chemotherapy and ≥17m post-RT or surgery. Median PFS and OS were 2.3m and 7.3m for all pts and 3.2m and 11.2m for arm B pts. There was 1 treatment-related death due to sepsis. Conclusions: Although neither arm met the prespecified endpoint, flavopiridol plus FOLFOX (arm B) was particularly active in LR pts, with a 50% overall RR, including several durable responses. Further study of FOLFOX with or without flavopiridol is warranted in LR pts. Correlative data will be presented. Clinical trial information: NCT00957905.