Costello, Brian A.

5053 Background: Genomic aberrations associated with resistance/response to AA/P are not known. In a prospective study we assessed whole-exome/RNA-seq based aberrations in CRPC metastatic biopsies for identifying molecular markers associated with primary resistance and response duration. Methods: Sequencing of metastatic biopsies was performed for analyzing molecular aberrations that predict primary resistance (defined as progression at 12-weeks of therapy (non-responders) using PSA, RECIST, bone scan criteria per PCWG2). Gene network analysis was performed in genes mutated more frequently in non-responders and in genes differentially expressed between non-responders and responders using a “risk ratio” (RR) of ≥2. Cox regression models with multiple gene network pathways were used for determining association with time to treatment change (TTTC). Results: Of 92 enrolled pts 82 had complete whole-exome, RNA-seq & 12-week outcome data available for analysis. At 12-weeks 33/82 had progressed. Using a RR of ≥2, 113 genes were more frequently mutated in non-responders & 292 in responders. In non-responders, gene network analysis revealed frequent mutations in Wnt/β-catenin pathway genes; frequent deletion of negative regulators of Wnt pathway ( DKK4, SFRP2, LRP6). Gene expression analyses revealed significantly reduced expression levels of Wnt/β-catenin pathway inhibitors and increased expression levels of cell cycle proliferation (CCP) genes in non-responders. Median study follow up was 32 months during which time 58/82 pts progressed and switched treatments. Median TTTC was 10.1 months (IQR:4.4-24.1). In multivariate analysis CCP scores of ≥50 predicted shorter TTTC (HR = 2.11, 95% CI: 1.17-3.80; p = 0.01). Conclusions: In metastases Wnt/β-catenin pathway activation is associated with primary AA/P resistance and increased CCP with acquired drug resistance. These findings offer molecular based predictive biomarkers in CRPC stage treatment. Clinical trial information: NCT#01953640.

e13073 Background: We observed several patients with a personal history of both RCC and myeloid malignancy, and aimed to explore a possible association, especially given the similarity in their epigenetic landscape, with both being characterized by widespread aberrant hypermethylation (Hu C et al, CCR 2014; Jiang Y et al, Blood 2009). Methods: Mayo Clinic’s ‘Advanced Cohort Explorer’ database was used to identify patients with a history of both RCC and a myeloid malignancy - Acute Myelogenous Leukemia (AML), Myeloproliferative Neoplasms (MPN), Myelodysplastic syndromes (MDS) - and to determine the clinical characteristics. The incidence of MDS in patients ≥65 years with a history of RCC was compared to that in the general population ≥65 years (SEER- Medicare database) as well as the general patient population at Mayo Clinic, using one sample test of proportions. Results: A total of 59 patients were identified, with both biopsy proven RCC and a myeloid malignancy during their life time (12 AML, 9 MPN, 9 low risk MDS and 29 intermediate- high risk MDS). The cohort was characterized by marked male predominance (4.4: 1). Median age at RCC diagnosis was 64 years (range 37-87) and myeloid malignancy was 75 years (range 44-90). 46/59 patients had the RCC antecedent, 10/59 concurrent and 3/59 subsequent to the myeloid malignancy with a median time of myeloid malignancy diagnosis after RCC diagnosis of 7.7 years. For patients ≥65 years, the risk of developing MDS with a history of stage I/II RCC and nephrectomy was 5.26 times that of the general population based on the SEER-Medicare database (Cogle, Blood 2011)(395/100,000 vs 75/100,000; p value < 0.001), and 3.07 times that of the general population at Mayo Clinic (395/100,000 vs 128.4/100,000; p value < 0. 001). Conclusions: We observed an association between RCC and myeloid malignancies, particularly MDS; with a history of RCC conferring a substantially increased risk of developing MDS. We hypothesize that the perturbation of epigenetic landscape in the form of widespread hypermethylation may explain, in part, the association between the two malignancies; and aim to explore the potential aberrancy of epigenetic regulators in our patient cohort with a genomic, epigenomic and transcriptomic analysis.

672 Background: The optimal sequence of cytoreductive nephrectomy (CN) and targeted therapy (TT) for patients with metastatic renal cell carcinoma (mRCC) remains to be established. Herein, we compared overall survival (OS) between patients with mRCC receiving initial CN with or without subsequent TT versus initial TT with or without subsequent CN. Methods: The National Cancer Database (NCDB) was used to identify patients diagnosed between 2006-2013 with RCC that was metastatic at diagnosis who received CN, TT, or both. Those with other prior cancer history were excluded. The cumulative incidence of receiving TT after CN and CN after TT were evaluated, with death prior to second treatment as a competing risk. To account for treatment selection bias, inverse probability of treatment weighting (IPTW) was performed based on the propensity to receive initial CN or TT. OS from diagnosis was compared using Cox regression. Sensitivity analyses were performed. Results: The cohort included 15,068 patients, of whom 6,731 underwent initial CN and 8,337 underwent initial TT. At 6 months from diagnosis, the probability of receiving TT after CN was 46.2%, with 13.6% of patients having died after initial CN prior to receiving TT. Meanwhile, the probability at 6 months of undergoing CN after initial TT was 4.4%, with 38.3% of this group having died prior to undergoing CN. In the IPTW analysis, baseline characteristics were balanced (standardized difference < 0.1). Initial CN was associated with improved OS compared to initial TT (median 16.5 vs 9.2 months; HR 0.62; 95%CI 0.61-0.64; p < 0.001). Findings were similar in all sensitivity analyses (propensity score matching and adjustment; regression adjustment; 6-month landmark analysis; clear cell mRCC subset; exclusion of patients who had metastasectomy). Conclusions: Although initial CN was associated improved OS versus initial TT in this national dataset, initial CN was associated with delays in, and even death prior to, receipt of TT. As such, while the survival data here support initial CN in appropriate surgical candidates, continued efforts to develop the optimal multimodal approach to these patients are warranted.

350 Background: In prostate cancer, overexpression of EZH2 is associated with disease recurrence, androgen independent growth, cell invasion, and metastases. We evaluated the prognostic significance of EZH2 gene expression in metastatic biopsies from men with CRPC. Methods: EZH2 (RNA) expression was evaluated in two serial metastatic site biopsies in patients (pts) prior to treatment with abiraterone acetate and prednisone (pre-AA/P) and after 12 weeks of treatment (post-AA/P). All pts were enrolled and prospectively followed for clinical outcomes. The primary endpoint was overall survival (OS), defined as the time from CRPC to death or last follow-up. Cox proportional hazard regression analysis was performed on EZH2 expression using normalized fragments per kilobase million (FPKM) > 1 for association with OS and time to treatment failure (TTF). Results: Of 92 enrolled pts, 59 pts had (pre-AA/P) gene expression using RNA-seq, 45 had paired pre and post-AA/P RNA-seq available for analysis. In pre-AA/P samples, the median EZH2 expression was 4.82 FPKMs (range 1.05-38.8). Elevated expression of EZH2 was associated with shorter OS [hazard ratio (HR) 2.58, p = 0.016]. Radiographic progression at 12 weeks was more frequent in high EZH2 tumors compared to low EZH2 tumors (48% vs 20%, p = 0.03, Fisher’s exact test) No statistically significant associations were identified between EZH2 expression and TTF. In paired post-AA/P biopsies, EZH2 expression increased in 13/45 tumors and decreased in 32/45 tumors. The median log2 fold change in EZH2 expression was -1.38 (range -6.7 to 3.1). In post-AA/P biopsies, no associations were identified between an increase in EZH2 expression and OS or TTF. Conclusions: EZH2 expression represents a potential novel prognostic biomarker in mCRPC and warrants further exploration. Clinical trial information: 01953640.

249 Background: Serum CGA has been identified as a candidate prognostic biomarker for mCRPC. In a two cohort study, we compared the prognostic value of serum CGA with a validated CTC assay. Methods: In the discovery cohort (DC), blood samples were collected from 256 men with mCRPC. In an independent validation cohort (VC), 92 men with mCRPC were enrolled in a biospecimen collection study. In both cohorts, men receiving proton pump inhibitors and those with non-castrate levels of testosterone ( > 50ng/dl) were excluded. Serum CGA was measured in a homogeneous automated immunofluorescent assay using time-resolved amplified cryptate emission. In the VC, CTC enumeration was performed using the FDA cleared CELLSEARCH CTC test prior to treatment with abiraterone acetate/ prednisone. Cox proportional hazard regression and Kaplan-Meier analysis were performed for associations with elevated CGA (above reference range), unfavorable (≥ 5) CTCs, and overall survival (OS). Results: In the DC, 200 men were eligible for analysis. The median age was 72 years (yrs), 81/200 pts had a Gleason score (GS) ≥ 8, 34/200 had an elevated CGA. At a median follow up of 2.2 yrs, 156/200 were deceased. In the subset of men with GS ≥ 8, elevated CGA was associated with shorter OS [hazard ratio (HR) 2.19, p = 0.017]. In the VC, 71 men were eligible for analysis. The median age was 71 yrs, 36/71 tumors were GS ≥ 8, 31/71 pts had an elevated CGA, 26/66 had unfavorable CTCs (≥ 5). At a median follow up of 1.8 yrs, 31/71 were deceased. Elevated CGA (HR 1.91, p = 0.043) and unfavorable CTC counts (HR 2.97, p = 0.0012) were adversely associated with OS. In the high GS group, both CTCs and CGA had the same area under the curve (AUC) of 0.72. Pts with elevated CTC and CGA had the poorest OS (HR 3.76, p = 0.008). Conclusions: Elevated serum CGA was negatively associated with OS in men with mCRPC. Serum CGA represents a prognostic biomarker that may complement CTC enumeration. Clinical trial information: NCT#01953640.

The Memorial Sloan Kettering Cancer Center (MSKCC) prognostic score is based on clinical parameters. We analyzed whole blood mRNA expression in metastatic clear cell renal cell carcinoma (mCCRCC) patients and compared it to the MSKCC score for predicting overall survival. In a discovery set of 19 patients with mRCC, we performed whole transcriptome RNA sequencing and selected eighteen candidate genes for further evaluation based on associations with overall survival and statistical significance. In an independent validation of set of 47 patients with mCCRCC, transcript expression of the 18 candidate genes were quantified using a customized NanoString probeset. Cox regression multivariate analysis confirmed that two of the candidate genes were significantly associated with overall survival. Higher expression of BAG1 [hazard ratio (HR) of 0.14, p < 0.0001, 95% confidence interval (CI) 0.04–0.36] and NOP56 (HR 0.13, p < 0.0001, 95% CI 0.05–0.34) were associated with better prognosis. A prognostic model incorporating expression of BAG1 and NOP56 into the MSKCC score improved prognostication significantly over a model using the MSKCC prognostic score only (p < 0.0001). Prognostic value of using whole blood mRNA gene profiling in mCCRCC is feasible and should be prospectively confirmed in larger studies.

Key Points Ibrutinib has modest activity in FL with low response rates in rituximab-refractory patients. CARD11 mutations predict for lack of response to ibrutinib.