Tangen, Catherine M.

Objective An understanding of the etiologic heterogeneity of colorectal cancer (CRC) is critical for improving precision prevention, including individualized screening recommendations and the discovery of novel drug targets and repurposable drug candidates for chemoprevention. Known differences in molecular characteristics and environmental risk factors among tumors arising in different locations of the colorectum suggest partly distinct mechanisms of carcinogenesis. The extent to which the contribution of inherited genetic risk factors for CRC differs by anatomical subsite of the primary tumor has not been examined. Design To identify new anatomical subsite-specific risk loci, we performed genome-wide association study (GWAS) meta-analyses including data of 48 214 CRC cases and 64 159 controls of European ancestry. We characterised effect heterogeneity at CRC risk loci using multinomial modelling. Results We identified 13 loci that reached genome-wide significance (p<5×10 −8 ) and that were not reported by previous GWASs for overall CRC risk. Multiple lines of evidence support candidate genes at several of these loci. We detected substantial heterogeneity between anatomical subsites. Just over half (61) of 109 known and new risk variants showed no evidence for heterogeneity. In contrast, 22 variants showed association with distal CRC (including rectal cancer), but no evidence for association or an attenuated association with proximal CRC. For two loci, there was strong evidence for effects confined to proximal colon cancer. Conclusion Genetic architectures of proximal and distal CRC are partly distinct. Studies of risk factors and mechanisms of carcinogenesis, and precision prevention strategies should take into consideration the anatomical subsite of the tumour.

5022 Background: Radical cystectomy (RC) is the standard of care for patients with BCG-unresponsive high risk non-muscle invasive bladder cancer (NMIBC), but many patients are unfit for surgery or elect bladder preservation. Based on the reported efficacy of atezolizumab in metastatic urothelial carcinoma and the known expression of PD-L1 in NMIBC after BCG therapy, this trial was designed to evaluate the activity of atezolizumab in BCG-unresponsive high risk NMIBC. Methods: This single arm phase II registration trial testing systemic atezolizumab (1200 mg IV) every 3 weeks for one year aimed to enroll 135 (70 CIS and 65 non-CIS) eligible patients with histologically proven BCG-unresponsive high risk NMIBC who were unfit for or declined RC. Here we report on the subset with CIS (with or without concomitant Ta/T1) among patients who received at least one protocol treatment. The primary endpoint was pathological complete response (CR) rate at 6 months as defined by mandatory biopsy with a null hypothesis of 30% and alternative of 50% with a 1-sided alpha = 0.05 and 96% power. The 3 month CR rate, defined by cytology, cystoscopy and for-cause biopsy, is reported here as a secondary endpoint, in addition to safety. Results: Seventy-five eligible CIS patients were enrolled. Two received no treatment and are not evaluable. Of 73, median patient age was 73.4 years and median number of prior BCG doses was 12. Concomitant Ta/T1 tumor was found in 30 (41.1%) patients, including T1 disease in 16 (21.9%). A CR was observed in 30 (41.1%; 95% CI 29.7%, 53.2%) patients at 3 months and 19 (26.0%; 95% CI 16.5%, 37.6%) at 6 months. Any possibly or probably treatment-related adverse event (AE) was observed in 61 (83.6%) patients. The most frequent AEs were fatigue 36 (49.3%), pruritis 8 (11.0%), hypothyroidism 8 (11.0%), and nausea 8 (11.0%). Grade 3-5 AEs occurred in 9 (12.3%) patients and there was one treatment-related death (myasthenia gravis with respiratory failure and sepsis). Conclusion: The observed response to atezolizumab at 3 and 6 months in patients with BCG-unresponsive CIS was similar to that reported in recent similar trials and meets the benchmark for initial CR defined by the FDA guidance. This trial provided no new safety concerns. The duration of response will determine if this is a suitable treatment option for patients with BCG-unresponsive high risk CIS. Clinical trial information: 02844816 .

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 &lt; 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.

Abstract Background: The Prostate Cancer Prevention Trial (PCPT) was a 7-year randomized, double-blind, placebo-controlled trial of the efficacy of finasteride for the prevention of prostate cancer with a primary outcome of histologically determined prevalence of prostate cancer at the end of 7 years. Methods: A systematic modeling process using logistic regression identified factors available at year 6 that are associated with end-of-study (EOS) biopsy adherence at year 7, stratified by whether participants were ever prompted for a prostate biopsy by year 6. Final models were evaluated for discrimination. At year 6, 13,590 men were available for analysis. Results: Participants were more likely to have the EOS biopsy if they were adherent to study visit schedules and procedures and/or were in good health (P &lt; 0.01). Participants at larger sites and/or sites that received retention and adherence grants were also more likely to have the EOS biopsy (P &lt; 0.05). Conclusions: Our results show good adherence to study requirements 1 year before the EOS biopsy was associated with greater odds that a participant would comply with the invasive EOS requirement. Impact: Monitoring adherence behaviors may identify participants at risk of nonadherence to more demanding study end points. Such information could help frame adherence intervention strategies in future trials. Cancer Epidemiol Biomarkers Prev; 23(8); 1638–48. ©2014 AACR.