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553 Background: Low-grade noninvasive (LGTa) bladder cancer is a relatively quiescent but heterogenous malignancy, characterized by downstream recurrences requiring repeated transurethral resections and frequent surveillance. Investigations to elucidate drivers of recurrence have been sparse, but will help risk-stratify patients with LGTa and allow augmentation of follow up protocols. Methods: Patients with LGTa index tumors were stratified by those with no downstream recurrences (nonrecurrent) vs. those with later recurrences (recurrent). RNA sequencing identified differentially expressed genes (DEGs), deconvoluted for cell-type using xCell. Pathologic analysis was performed by a genitourinary pathologist, then a deep-learning artificial intelligence (AI) platform was leveraged to correlate recurrence risk and recurrence-free survival (RFS) based on deep-learning algorithm of segmented nuclei. Results: Thirty index bladder tumors/patients were identified, 18 (60%) of which had later recurrence (Table). There were 238 DEGs recognized, with recurrent tumors expressing signatures for epithelial mesenchymal transition, myogenesis, TNFα signaling via NFκB, and angiogenesis. Recurrent tumors also demonstrated a higher tissue micoenvironment, stroma, and cancer-associated fibroblast score. Pathologic TME analysis validated these findings, with recurrent tumors demonstrating a higher frequency of inverted growth pattern and a higher median stroma percentage. Finally, the AI-derived signature was predictive of recurrence and risk-stratified the cohort (HR= 5.43 [95% CI 1.1-26.76]) for predicting high vs. low risk of recurrence. Patients in the high risk group had a 87.5% recurrence rate while those in the low risk group had a 28.5% recurrence rate (p

519 Background: Successful therapeutic cancer prevention requires definition of the minimal effective dose of the proposed agent. Aromatase inhibitors substantially decreased breast cancer incidence in high risk postmenopausal women in phase III trials but their clinical use in prevention and adherence in adjuvant setting is limited by adverse events. We conducted a randomized presurgical phase IIb trial to evaluate two alternative doses of exemestane. Methods: We conducted a multi-center, pre-surgical, double-blind, 3-arm, non-inferiority phase IIb study in postmenopausal women with histologically confirmed estrogen receptor (ER)-positive breast cancer. Patients were randomized to receive either exemestane 25 mg/day (QD), or 25 mg/three times/week (TIW), or 25 mg once a week (QW) for 4-6 weeks before surgery. Blood and tissue biomarkers were collected at baseline and final visit. The primary aim was a non-inferiority percent change of circulating estradiol relative to the standard dose. Secondary endpoints were the change in Ki-67 and PgR expression in cancer tissue, blood sex hormones, lipid profile, toxicity and menopausal symptoms. For the power calculation we assumed a non-inferiority difference of 6% in the percentage change of estradiol among arms, using a one-sided, two-sample t-test. Assuming a 10% drop-out rate, a total sample size of 180 participants (60 per arm) had 80% power to detect a 6% margin of equivalence. The significance level for the main endpoint was 0.025 to account for multiple comparisons and 0.05 for secondary endpoints. Results: A total of 230 women were screened, 180 agreed to participate and 173 were evaluable for response. The median percent change of estradiol was -98%, -98%, and -70% for exemestane QD (n = 56), TIW (n = 57), and QW (n = 60), respectively, showing no significant difference between QD and TIW arms (p = 0.9). Similarly, no differences were observed for estrone, total estrone and estrone sulfate between QD and TIW arms. The QW arm showed some modulation in all hormones, even though less significantly so. Among the secondary endpoints, Ki-67 and PgR were reduced in all arms, with a median change of -5% vs -7.5% for Ki-67(p = 0.124), and -9 vs -17 for PgR (p = 0.246) in the TIW vs QD arms, respectively. SHBG and HDL-cholesterol had a more favorable profile with the TIW dose compared to the daily dose. Adverse events, measured according to the CTCAE (v4), and menopausal symptoms according to MENQOL were similar in all arms, but the short treatment time may not be representative. Conclusions: Exemestane 25 mg TIW retains a comparable activity than 25 mg QD. This activity was similar in both arms throughout the primary and the main secondary endpoints. This new schedule should be further assessed in prevention studies and in women on adjuvant treatment who do not tolerate the daily dose. Clinical trial information: NCT02598557.

On November 3, 2014, in Bethesda, MD, the Office of Cancer Complementary and Alternative Medicine of the National Cancer Institute held a meeting to examine the potential utility and feasibility of establishing an international consortium for Chinese medicine and cancer. There is significant interest in the West in using components of Chinese medicine (CM) —such as botanicals and herbal medicines, acupuncture and acupressure, and qigong—in the field of oncology, as potential anticancer agents, for symptom management, and to improve quality of life. The proposal for a consortium on CM came from the Chinese Academy of Chinese Medical Sciences, with the aims of improving scientific communications and collaborations and modernizing the studies of CM for cancer. The US National Cancer Institute’s Office of Cancer Complementary and Alternative Medicine agreed to work with Chinese Academy of Chinese Medical Sciences to explore the feasibility of establishing an international consortium for Chinese medicine and cancer. At the meeting, participants from the United States, China, Canada, Australia, and Korea discussed issues in CM and cancer research, treatment, and management, including potential mechanisms of action, proof of efficacy, adverse effects, regulatory issues, and the need for improving the quality of randomized clinical trials of CM treatments and supportive care interventions. Presented in these proceedings are some of the main issues and opportunities discussed by workshop participants.

e21155 Background: Over 50% of new lung cancers occur in former smokers, who often are seeking strategies to reduce their lung cancer risk. However, recruitment and retention of participants in chemoprevention trials continues to be costly and presents unique challenges. Evaluation of feasibility and knowledge of challenges are critical to inform design and ensure accrual in chemoprevention trials.The study assessed interest and willingness of former heavy smokers to participate in a chemoprevention clinical trial using a botanical agent to prevent lung cancer. Methods: An introductory letter and survey instrument that included the goal of the survey, epidemiological and smoking history, acceptability of trial procedures, perception of lung cancer risk and interest in participating in this trial were mailed to 500 consecutive, former heavy smokers with no cancer from a database of 826 subjects at the Moffitt Cancer Center. Results: 202 (40.4%) men and women returned completed surveys. 98% of respondents were over age 60 and 56% had an undergraduate education or higher. The average years smoked was 40.7 (SD 11.9) pack years. 76% believed there was a 50% chance or greater of developing lung cancer. In response to interest and motivation to participate, 92-96% reported interest in receiving free lung exams, health status monitoring and knowing their lung cancer risk. 88% were interested in being a part of a trial to evaluate a botanical agent for lung cancer prevention. Over 92% of subjects reported a willingness to comply with study requirements, multiple blood draws and trips to the Center, spiral CTs and chest x-rays. Subjects were relatively less enthusiastic (73-79%) about undergoing bronchoscopy, taking multiple study agents and possible assignment to a placebo arm. Conclusions: Our study strongly suggests feasibility, highlights potential challenges and the significant interest and willingness of former smokers to participate in chemoprevention trials.