Citations

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.

348 Background: Patients (pts) with mUC have few treatment options beyond the second-line setting. HER2 gene amplification has been reported in a minority of pts with UC, but there have been anecdotal reports of the activity of HER2-targeted agents. MyPathway is a multi-basket study evaluating the efficacy and safety of targeted therapies in non-indicated tumor types harboring relevant molecular alterations. We present preliminary data for pts with HER2-positive mUC receiving HER2-targeted treatment with pertuzumab + trastuzumab. Methods: MyPathway (NCT02091141) is an open-label, multicenter, phase IIA study. Pts in this subset analysis had refractory mUC with HER2 amplification or putative activating mutations by gene sequencing, FISH, or IHC. Pts received standard doses of pertuzumab + trastuzumab without chemotherapy until disease progression or unacceptable toxicity. The primary endpoint is investigator-assessed overall response rate (RECIST v1.1). Results: As of July 31, 2016, 12 pts with platinum-resistant HER2-positive mUC (HER2-amplified, n=9; HER2-mutated, n=3) have been enrolled. At a median follow-up of 5.4 (range 0.9–14.5) mos, 1 pt had complete response (CR, ongoing at 12.5 mos), 2 had partial responses (PR; duration of response, 3.7 and 5.5 mos), and 2 had stable disease (SD) for >4 mos (Table). Safety was consistent with the product labels. Conclusions: Preliminary results indicate that the combination of pertuzumab + trastuzumab has activity in previously treated HER2-amplified mUC, including a durable CR in a pt with peritoneal metastases. Accrual to MyPathway is ongoing. Clinical trial information: NCT02091141. [Table: see text]

312 Background: Radical cystectomy (RC) is a preferred option for high−grade non−muscle invasive bladder cancer (HG NMIBC), particularly after failure of intravesical therapy. However, clinicians may be reluctant to offer surgery to older patients with NMIBC given concerns regarding morbidity. We therefore sought to evaluate the association of age with use of RC and clinicopathologic outcomes after RC for HG NMIBC. Methods: The National Cancer Data Base was queried to identify patients diagnosed with HG NMIBC between 2004−2013. Patients were stratified according to age at diagnosis: <60, 61−70, 71−80, >80 years. Multivariable logistic regression was performed to assess the associations of age group with utilization of RC and with pathologic upstaging (pT2−4 or pN+). Overall survival (OS) was evaluated using unadjusted and inverse propensity score weighted (IPTW) Kaplan−Meier methods and compared with the log-rank test. Results: RC was performed in 3,641 (5.7%) of 63,402 patients with HG NMIBC. Utilization of RC remained relatively constant over the study period (4.3%−6.8%; p=0.44). On multivariable analysis, increasing age was inversely associated with RC utilization, with the lowest utilization in those >80 (2.1% rate; OR 0.24; p<0.01). Similar associations of age with RC were observed at high volume centers (> 15 cases/year), academic centers, and for patients with cT1 disease. Among patients who underwent RC, pathologic upstaging was identified in 1,445 (43.6%), and no significant association was noted with age. NMIBC pathologic tumor stage was associated with improved OS compared to progression to pT2−4 or N+ disease at RC for all age groups: median OS improvement not reached in those under 60; 32 months in those 61−70; 55 months in those 71−80; and 34 months in those over 80 (all p<0.01). Similar improvements in survival were noted after IPTW. Conclusions: Older patients are significantly less likely to receive RC for HG NMIBC, despite a similar risk of upstaging and an improved survival when pathologic NMIBC is found at RC. These data support the use of RC for HG NMIBC in well selected patients across age strata.

308 Background: Receipt of pelvic radiotherapy (PRT) prior to radical cystectomy (RC) has unclear association on oncologic outcomes. Methods: The Mayo Clinic Cystectomy Registry was queried to review 2139 patients undergoing RC for M0 bladder cancer between 1990 and 2010. We then identified patients receiving PRT prior to RC, and matched these cases to non-radiated controls (~1:2) on the basis of age, sex, receipt of neoadjuvant chemotherapy, and pathologic T and N stages. Cancer-specific survival (CSS), and progression-free survival (PFS) were estimated using the Kaplan-Meier method and compared with the log-rank test. Results: Of 2139 patients undergoing RC, 104 (4.9%) had received PRT prior to surgery. These patients were matched to 191 non-radiated control patients (no PRT). Overall, patients were well-matched on disease and patient characteristics. Median follow-up was 9.6 years (IQR 6.0, 14.8). During this time, 108 patients experienced disease recurrence and 218 died, including 122 who died from bladder cancer. Five-year CSS among patients who did versus did not receive PRT was 55% versus 63% (p=0.10), while the 5-year PFS was 55% versus 61% (p=0.32). Furthermore, the pattern of disease recurrence (abdominal/visceral, urothelial, local/pelvic, thoracic, soft tissue/other) did not differ between the no PRT and PRT groups (all p>0.05). Conclusions: Receipt of PRT prior to RC is not associated with worse oncologic outcomes. While prior PRT may increase surgical complexity, CSS, PFS, and patterns of recurrence are similar to patients who have not received PRT.

3 Background: There is a clear need to develop a clinically relevant molecular subtyping approach for prostate cancer. We hypothesized that prostate cancer can be subtyped based on luminal versus basal lineage. Methods: We applied the PAM50 classifier, which is used clinically to identify luminal and basal cancers in breast cancer, to subtype a total of 3,782 prostate cancer samples using a high-density microarray platform run in a CLIA-certified laboratory. We examined the associations of these subtypes and clinical outcomes. Results: We demonstrate that PAM50 segregates prostate cancer into three reproducible subtypes in both retrospective cohorts and on prospective validation: luminal A (33.3%-34.3%), luminal B (28.5%-32.6%), and basal (34.1%-37.1%). Luminal B prostate cancers exhibited the worst clinical prognoses, followed by basal and luminal A subtypes (10-year biochemical recurrence-free survival: 29/39/41%; distant metastasis-free survival: 53/73/73%; prostate cancer-specific survival: 78/86/89%; overall survival: 69/80/82% respectively) on both univariable and multivariable analyses accounting for standard clinicopathologic prognostic factors. Known luminal lineage markers, such as NKX3.1 and KRT18, and the basal lineage CD49f signature, were enriched in luminal- and basal-like cancers respectively, demonstrating the connection between these subtypes and established prostate cancer biology. While both luminal-like subtypes were associated with increased AR expression and signaling, only luminal B prostate cancers were significantly associated with post-operative response to androgen deprivation therapy (ADT) in a subset analysis matching patients based on clinicopathologic variables (interaction p = 0.006, luminal B 10-year metastasis: 33% (treated) vs. 55% (untreated), non-luminal B: 37% (treated) vs. 21% (untreated)). Conclusions: These findings contribute novel insight into the biology of prostate cancer, and provide translatable clinical tools for personalizing post-operative ADT for patients with prostate cancer. Similar to breast cancer, these findings suggest that luminal/basal subtyping may be useful in treatment selection in prostate cancer.

279 Background: While bacillus Calmette-Guérin (BCG) is the most effective intravesical treatment for reducing recurrence and progression for high-risk non-muscle invasive bladder cancer (NMIBC), many patients are either refractory to treatment or relapse. We assessed the efficacy and safety of rAd-IFNα/Syn 3 (Instiladrin, FKD Finland), a replication deficient recombinant adenovirus gene transfer vector, for patients with high-grade (HG) BCG refractory or relapsed NMIBC. Methods: In this open-label, US multicenter (n=13), parallel-arm Phase II study (NCT01687244), 43 patients with HG BCG refractory or relapsed NMIBC were randomized 1:1 to receive intravesical rAd-IFNα/Syn3 at 1x1011 or 3x1011viral particles/mL. Patients responding at months 3, 6, and 9 were re-treated at months 4, 7, and 10. Most patients (n=21) had a primary tumor classification of carcinoma in situ (CIS); 9 had both CIS and Ta/T1 disease and 10 had Ta/T1 disease alone. The primary endpoint was 12-month HG recurrence-free survival (RFS). All patients receiving at least one dose were included in efficacy and safety analyses. Results: Forty patients received rAd-IFNα/Syn3 (1 x 1011 vp/mL: n=21; 3 x 1011vp/mL: n=19) between November 2012 and April 2015. Fourteen patients (35.0%; 90% CI 22.6%, 49.2%) remained free of HG tumor recurrence 12 months after initial treatment. Comparable 12 month HG RFS was noted between dosage arms, as well as between patients with refractory and relapsed NMIBC. Interestingly, the 12 month HG recurrence-free survival for patients with Ta/T1-only disease was 50% (5/10). rAd-IFNα/Syn3 was well-tolerated, with no Grade 5 adverse events (AEs), one Grade 4 AE (COPD; unrelated to treatment), and no patient discontinuing treatment due to an adverse event. The most frequently reported AEs were micturition urgency (n=16), dysuria and pollakiuria (n=13 each), fatigue (n=9), and nocturia (n=10). Conclusions: rAd-IFNα/Syn3 was well tolerated and demonstrated promising efficacy for patients with HG NMIBC after BCG therapy who are unable or unwilling to undergo radical cystectomy. A phase III trial utilizing this novel agent is ongoing. Clinical trial information: 01687244.

241 Background: Androgen deprivation represents the standard treatment for PCA with osseous metastases. We explored the role of cRP in the largest cohort of contemporary patients with mPCA treated in 4 tertiary referral centres. Methods: A total of 114 patients with mPCA, lymph node, osseous or visceral metastases underwent cRP. Surgery related complications (Clavien-Dindo classification) and functional outcome were analysed. Oncologic outcome parameters such as cancer specific & overall survival as well as biochemical and clinical-free survival were evaluated using descriptive statistical analysis. Results: Mean patient age was 61 (42-69) years. Mean and median follow-up was 39.7 months (7-75) and 47 months (28-96), resp. 93 (81.6%) and 21 (18.4%) patients had low volume and high volume mets, resp.,. 80(70.2%) pts underwent neoadjuvant ADT with LHRH analogues. Surgical approach was open retropubic RP in 104 (92%) pts and 2 (1.8%), 10 (8.8%) and 101 (89.4%) pts underwent no, limited or extended pelvic LAD, resp. Adjuvant therapy was delivered in 99 (86.8%) pts. Pathohistology revealed significant vital PCA in 100% of cases: n = 16 (14.0%) exhibited pT4a, n = 21 (18.4%) had pT2 and the remainder had pT3a/b PCA. Positive lymph nodes or positive surgical margins were identified in 61.6% and 36.8%, resp.. 110 (96.5%) are alive and 66.7% are relapse-free. 74 (64.9%) pts did not experience any surgery related complications; 15 (13.1%) pts experienced Clavien Dindo grade IIIb/IV complications and underwent reintervention. Low versus high volume (32.2% vs 50%, p = 0.03), PSA at cRP < 1ng/ml vs PSA > 4 ng/ml, (18.9% vs 45.6%, p = 0.02) were associated with relapse. Low vs high volume disease (7.1% vs 32.1%), PSA < 4ng/ml vs PSA > 4 ng/ml (6.1% vs 47.8%) and neoadjuvant vs no neoadjuvant therapy (8.75% vs 24.2%) were associated with Clavien-Dindo IIIB complications (p < 0.05). Conclusions: cRP is feasible in men with mPCA independent on the extent of disease with a low rate of significant complications and good functional outcome. About two thirds of the patients remain relapse-free after a median follow-up of close to 4 years. cRP might be an individualized treatment option in the multimodality management of mPCA.

181 Background: To evaluate whether metformin (Met) a widely-used, nontoxic oral antidiabetic drug with putative anticancer properties leads to improvements in prostate cancer (PC) outcomes in the CHAARTED trial. Methods: In the CHAARTED database where metformin use at baseline was recorded prospectively, we identified patients with metastatic PC who underwent either ADT alone or ADT and docetaxel (D) chemotherapy. Cox proportional hazards models were used to determine the effect of Metformin on outcomes. Results: A total of 788 patients (median age, 63 y) had complete data after randomization. Comparison of ADT+D+Met (n = 39) to ADT+D (n = 357) and ADT+Met (n = 29) to ADT alone (n = 363) revealed similar clinicopathologic characteristics. Cause of death was PC in 13(81%) of ADT+D+Met, 72(85%) ADT+D, 9(82%) ADT+Met and 105(84%) ADT alone groups. See table for PC outcomes and overall survival by metformin use. Cox regression analysis for overall survival stratified by stratification factors at randomization demonstrates Met use was associated with a trend for worse overall survival (HR 1.47 95%CI: [0.95,2.26], p = 0.08) with adjustment for treatment arm and prior local therapy. In contrast, ADT+D use (HR 0.62; 95%CI: [0.47,0.81]) and prior local therapy with surgery or radiation (HR 0.56; 95% CI: [0.38, 0.82]) were associated with improved survival. Conclusions: In this study, baseline metformin did not improve PC outcomes. Partial support and drug supply by Sanofi. Clinical trial information: NCT00309985. [Table: see text]

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.

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.