Kim, Jeri

Abstract Background: Whether associations between circulating metabolites and prostate cancer are causal is unknown. We report on the largest study of metabolites and prostate cancer (2,291 cases and 2,661 controls) and appraise causality for a subset of the prostate cancer–metabolite associations using two-sample Mendelian randomization (MR). Methods: The case–control portion of the study was conducted in nine UK centers with men ages 50–69 years who underwent prostate-specific antigen screening for prostate cancer within the Prostate Testing for Cancer and Treatment (ProtecT) trial. Two data sources were used to appraise causality: a genome-wide association study (GWAS) of metabolites in 24,925 participants and a GWAS of prostate cancer in 44,825 cases and 27,904 controls within the Association Group to Investigate Cancer Associated Alterations in the Genome (PRACTICAL) consortium. Results: Thirty-five metabolites were strongly associated with prostate cancer (P < 0.0014, multiple-testing threshold). These fell into four classes: (i) lipids and lipoprotein subclass characteristics (total cholesterol and ratios, cholesterol esters and ratios, free cholesterol and ratios, phospholipids and ratios, and triglyceride ratios); (ii) fatty acids and ratios; (iii) amino acids; (iv) and fluid balance. Fourteen top metabolites were proxied by genetic variables, but MR indicated these were not causal. Conclusions: We identified 35 circulating metabolites associated with prostate cancer presence, but found no evidence of causality for those 14 testable with MR. Thus, the 14 MR-tested metabolites are unlikely to be mechanistically important in prostate cancer risk. Impact: The metabolome provides a promising set of biomarkers that may aid prostate cancer classification.

169 Background: Cabozantinib (Cabo), a tyrosine kinase inhibitor of c-Met and VEGFR2, modulates the tumor microenvironment in a therapeutically favorable manner. We combined Cabo with androgen deprivation therapy (ADT) in patients (pts) with androgen-dependent metastatic prostate cancer (PCa) (NCT01630590). Methods: Pts received Cabo (starting dose 60 mg PO daily) and ADT with a GnRH analogue. Pts could receive up to 3 months of ADT prior to initiating Cabo. Bone scan (BS) and CT scans were performed every 12 weeks (wks). Efficacy endpoints included response in markers, BS and RECIST, and time to castrate-resistant progression defined by radiographic progression, clinical progression, or receipt of additional anti-cancer therapy. Results: From 01/27/2014 to 01/12/2016, 62 pts were enrolled: 94% (58/62) with bone metastasis, 56% (35/62) with measurable disease, 15% (9/62) with visceral involvement and 26% (16/62) with prior treatment of their primary tumor. 79% (49/62) of pts have high volume disease defined by > 4 bone lesions and/or involvement of viscera. Median time from start of ADT to start of Cabo was 3.4 wks. Improvements in BS were observed in 81% (44/54) of evaluable pts including complete responses (CR) in 15% (8/54). In evaluable pts with measurable disease, best response was stable disease in 9% (3/33), PR in 61% (20/33) and CR in 30% (10/33). Reductions in PSA > 90%, bone specific alkaline phosphatase > 50% and urine N-telopeptides > 50% occurred in 83% (50/60), 87% (34/39), 86% (19/22) of evaluable pts, respectively. With a median follow up of 21.4 months (mo), median PFS is 15.6 mo. Median duration of Cabo treatment is 13 mo. Most common toxicities are Grade 3 hypertension (16%), pulmonary embolus (6%), diarrhea (4%), fatigue (3%), nausea (3%), and deep venous thrombosis (3%) with no Grade 4 events. Cabo dose reductions to 40 and 20 mg occurred in 68% and 18% of pts, respectively, with discontinuations due to toxicity in 10% of pts. Conclusions: Cabo plus ADT has potent clinical activity in pts with high volume androgen-dependent PCa including improvements BS and reduction in markers of bone stromal function. Studies are underway to identify biomarkers predictive of best response. Clinical trial information: NCT01630590.

250 Background: Testicular germ cell tumor survivors (TGCTSs) contend with treatment side effects for decades after cure, and many have metabolic syndrome (MTS), a modifiable cardiometabolic risk factor. Because reliably predicting MTS could prompt interventionreducing risk, we analyzed clinical data and body composition in computed tomography (CT) scans to identify associations. Methods: In a retrospective review of 196 TGCTSs treated at a single institution from 1970 to 2007, we collected patient (pt) demographics, clinical data, body fat composition measures, and evidence from CT scans from baseline through posttreatment. NIH Image J was used to analyze cross-sectional CT images and measured subcutaneous adipose tissue, visceral adipose tissue, and skeletal muscle. Visceral fat-to-muscle ratio (VMR), visceral-to-subcutaneous fat ratio (VSR), and change in VMR and VSR from baseline to 3 to 5 years posttreatment (ΔVMR and ΔVSR) were calculated. We also gathered posttreatment glucose, blood pressure, lipid data, and body weight and height measured at time of scans. The 2001 U.S. National Cholesterol Education Program Adult Treatment Panel III guideline defined MTS. Univariate and multivariate logistic regression analyses identified associations. Results: Of the 167 pts included in the final analysis, 37.7% had MTS, 76.6% were white, and 68.9% had chemotherapy. Pts with MTS had significantly higher VMRs (p = .007) and VSRs (p = .021) than those without. Pts receiving chemotherapy and radiotherapy were significantly more likely to have MTS (p = .044 and p = .037). A multinomial logistic regression model including year of diagnosis, age, race, tumor histology, treatment, VSR, and VMR identified the association of high VMR and VSR with MTS; ΔVMR and ΔVSR were not statistically significant predictors. Conclusions: Body composition analyses identified VMR and VSR as significant predictors of MTS.

AbstractThis article reviews progress in chemopreventive drug development, especially data and concepts that are new since the 2002 AACR report on treatment and prevention of intraepithelial neoplasia. Molecular biomarker expressions involved in mechanisms of carcinogenesis and genetic progression models of intraepithelial neoplasia are discussed and analyzed for how they can inform mechanism-based, molecularly targeted drug development as well as risk stratification, cohort selection, and end-point selection for clinical trials. We outline the concept of augmenting the risk, mechanistic, and disease data from histopathologic intraepithelial neoplasia assessments with molecular biomarker data. Updates of work in 10 clinical target organ sites include new data on molecular progression, significant completed trials, new agents of interest, and promising directions for future clinical studies. This overview concludes with strategies for accelerating chemopreventive drug development, such as integrating the best science into chemopreventive strategies and regulatory policy, providing incentives for industry to accelerate preventive drugs, fostering multisector cooperation in sharing clinical samples and data, and creating public-private partnerships to foster new regulatory policies and public education.