Citations

4657 Background: While active surveillance (AS) is well recognized as an acceptable treatment strategy for low-risk prostate cancer (PC), the extent to which radiation oncologists and urologists perceive AS as effective and routinely recommend it to patients is unknown. Therefore, we sought to assess the attitudes and treatment recommendations for low-risk PC from a national survey of PC specialists. Methods: A mail survey was sent to a population-based sample of 1,439 physicians in the U.S. from late 2011 and early 2012. Physicians were queried about their attitudes regarding AS and treatment recommendations for patients diagnosed with low-risk PC (PSA<10 ng/dl; T1c; Gleason 6 in one of twelve cores). Pearson Chi-square and multivariate logistic regression were used to test for differences in attitudes and treatment recommendations by physician demographics, compensation structure, primary place of employment, and specialty. Results: Overall, 321 radiation oncologists and 322 urologists completed the survey for a 45% response rate. Most physicians reported that AS is effective for low-risk PC (71%) and stated that they were comfortable routinely recommending AS (67%). Urologists were more likely to agree that AS is effective (77% vs. 67%; p=0.005) and were comfortable recommending AS (74% vs. 61%; p=0.001) compared with radiation oncologists. Most physicians recommended radical prostatectomy (47%) or radiation therapy (32%), but fewer endorsed AS (21%) for low-risk disease. After adjusting for physician covariates, radiation oncologists were more likely to recommend radiation therapy (OR: 10.97; p<0.001), while urologists were more likely to recommend surgery (OR: 4.69; p<0.001) and AS (OR: 2.18; p=0.001) for low-risk PC. Conclusions: Although AS is widely viewed as effective by both radiation oncologists and urologists, most urologists continue to recommend surgery, while most radiation oncologists recommend radiation therapy. Our results may explain in part the relatively low contemporary use of AS in the U.S.

4565 Background: The efficient delivery of adjuvant therapy after radical prostatectomy (RP) in patients with prostate cancer is limited by the lack of biomarkers, beyond clinicopathologic factors, that are able to assess the risk of clinically significant disease progression. Previously, routine FFPE patient specimens from the Mayo Clinic Radical Prostatectomy Registry with long term follow-up were selected to develop a genomic classifier (GC) to predict clinical progression. Here, we present the validation of a GC in a cohort of patients at high risk of disease progression. Methods: A case-cohort study of high-risk RP patients from the Mayo Clinic (N=219) was used to validate the genomic classifier (GC) for predicting clinical progression (defined by positive bone or CT scan post-RP). Its performance was compared to a multivariable clinical classifier (CC) and a genomic-clinical classifier (GCC) which combines GC with established clinicopathologic variables. Concordance index, Cox modeling and decision curve analysis were used to compare the different models. Results: GC and GCC were predictive of clinical progression in the high-risk cohort with c-indices of 0.79 and 0.82, respectively, compared to the clinical classifier (0.70). Multivariable survival analysis showed that the majority of prognostic information of GCC came from the GC with a minor contribution from Gleason score. Decision curve analysis showed that GCC had a higher overall net benefit compared to CC over a wide range of ‘decision-to-treat’ thresholds for the risk of progression. Conclusions: In this high-risk cohort, GC and GCC classifiers showed improved performance over CC in prediction of clinical progression. GC is an independent prognostic factor in this cohort and captures the majority of prognostic information. GC and GCC’s prognostic performance and their usefulness in guiding decision-making in the adjuvant setting after RP need further testing in studies of additional prostate cancer risk groups.

TPS380 Background: Radical prostatectomy (RP) is the most common surgical treatment for prostate cancer (PC). Yet even with nerve-sparing RP (NS-RP), a significant proportion of men experience transient or permanent erectile dysfunction (ED) partially due to intraoperative neurovascular bundle (NVB) damage from thermal or mechanical trauma. Studies have shown that platelet released growth factors counteract trauma and facilitate healing. We evaluate the use of platelet rich plasma (PRP) to facilitate early nerve healing and decrease ED after NS-RP. Methods: A prospective, open label, 20 subject human trial evaluating intraoperative topical NVB PRP application was approved by the IRB and FDA under an Investigational Device Exemption (IDE 16915) for the investigational use of an approved blood separation device. Men aged 50-60 with newly diagnosed, localized PC and normal preoperative sexual and urinary function, defined as a Sexual Health Inventory for Men (SHIM) score of >19 and an answer of “none” on question 5 of the Expanded Prostate Cancer Index Composite (EPIC) are eligible. Intraoperatively, a 10ml PRP product is created from a 180 mL sample of the patient’s whole blood using the Angel Concentrated Platelet Rich Plasma System (Cytomedix, Inc., Gaithersburg, MD USA). PRP is applied via mechanical transfer to the NVB after completion of the vesicourethral anastomosis. The primary endpoint is the safety and tolerability of PRP on the NVB after NS-RP. Secondary endpoints include feasibility of intraoperative PRP application and longitudinal assessment of erectile function and urinary continence by questionnaire administration at 3, 6, 9, 12 and 18 months after NS-RP. Clinical trial information: NCT02957149.

483 Background: We evaluate the impact of salvage intravesical therapy on survival in patients with NMIBC previously treated with BCG who ultimately underwent radical cystectomy (RC). Methods: We retrospectively identified patients with NMIBC who received at least 1 complete induction course of BCG and subsequently underwent RC for bladder cancer between 2000-2018. Patients were stratified by receipt of salvage intravesical therapy following BCG prior to RC. Oncologic outcomes were compared using Cox proportional hazards regression analysis and the Kaplan-Meier method. Results: We identified 371 patients who underwent RC after receiving BCG, of whom 55 (15%) received salvage intravesical therapy, most commonly Mitomycin C (n = 26), Valrubicin (n = 8), Gemcitabine (n = 7), and CG0070 (n = 6). Median follow-up among survivors was 1.1 (IQR 0-4.3) years. Patients who received salvage intravesical therapy were more likely to initially present with CIS (27% vs 17%) and less likely to present with T1 disease (33% vs 50%, both p < 0.05). Receipt of salvage intravesical therapy was not associated with increased risk of adverse pathology (≥pT2 or pN+) at RC (33% vs 41%, p = 0.27). Furthermore, on Kaplan-Meier analysis, receipt of salvage intravesical therapy was not associated with cancer-specific or overall survival. On multivariable Cox proportional hazards regression, clinical stage prior to RC, but not receipt of salvage intravesical therapy, was associated with inferior cancer-specific survival and overall survival. Conclusions: Our results suggest that RC following carefully managed salvage intravesical therapy after BCG is not associated with inferior oncologic outcomes, which can improve patient counseling. [Table: see text]

337 Background: Current risk stratification schema have limited prognostic performance in predicting outcome within National Comprehensive Cancer Network (NCCN) high-risk to very high-risk prostate cancer. Methods: Two multicenter high-risk cohorts were used for training (n = 214) and validation (n = 151) of a novel RNA microarray-based integrated clinical-genomic Classifier Optimized for Outcome in High-risk Prostate cancer (COOHP) to classify patients as COOHP favorable high-risk, standard high-risk, or very high-risk. Cox analysis was used to model metastasis-free survival (MFS), prostate cancer-specific survival (PCSS), and overall survival (OS). Model performance was compared to prior sub-classification systems using time-dependent c-indices. Results: Among NCCN high/very high-risk patients in the training cohort, 11% were classified as COOHP favorable high-risk, 70% as COOHP standard high-risk, and 18% as COOHP very high-risk. Patients with COOHP favorable high-risk disease had better rates of 5-year MFS compared to those with COOHP standard high-risk disease (94% vs 76%, hazard ratio [HR] 0.10, p = 0.02), and patients with COOHP very high-risk disease had worse 5-year MFS compared to those with COOHP standard high-risk disease (34% vs 76%, HR 3.5, p < 0.0001). Similarly, patients with COOHP very high-risk disease had worse 10-year PCSS compared to those with COOHP standard high-risk disease (36% vs 82%, HR 4.4, p < 0.0001). The c-indices for 5-year MFS and 10-year PCSS in the training cohort were 0.80 and 0.74, significantly improved compared to prior clinical and clinical-genomic risk stratification systems (0.62-0.69 for 5-year MFS and 0.56-0.63 for 10-year PCSS). These results were consistent in the validation cohort, where 5-year MFS significantly varied among the three COOHP subgroups (100% vs 89% vs 79%, p = 0.020), as did 10-year OS (100% vs 71% vs 53%, p = .040). Conclusions: A clinical-genomic risk stratification system specifically designed to discriminate prognosis in high-risk prostate cancer better identified favorable high-risk and very high-risk subsets of disease compared to prior clinical and clinical-genomic stratification systems.

295 Background: While 18F-fluciclovine PET/CT is approved in the US and recommended by the NCCN, prostate-specific membrane antigen (PSMA) PET/CT is more common in Europe/Australia and recommended by the EAU. Less is known about the biology of lesions detected by either modality. 18F-fluciclovine PET relies on radiotracer uptake by amino acid transporters LAT1-4 and ASCT1-2. PSMA PET is dependent on surface expression of PSMA. We compared relative expression of PSMA and fluciclovine transporter genes in radical prostatectomy (RP) samples to determine their distribution across subtypes and correlation with outcomes. Methods: Gene expression data of 19,102 RP samples were analyzed using the Affymetrix Human Exon 1.0 ST microarray. 1,135 patients had long term follow up. Associations between expression of PSMA and fluciclovine transporter genes (LAT1-4 and ASCT1-2) and pathologic variables, molecular subtypes, and clinical outcomes were conducted. Results: All fluciclovine transporter genes (LAT 1-4, ASCT1-2) were expressed at lower levels than PSMA (p <0.0001). PSMA expression was positively correlated with genomic risk score and pathologic Gleason score (p<0.0001), but LAT2-3 and ASCT2 were inversely correlated with genomic risk in primary tumors (p<0.0001) and less expressed in GS 9-10 tumors (p<0.0001). PSMA expression was associated with worse metastasis-free survival (MFS) (HR 1.45, p=0.001) and lymph node involvement (HR 2.14, p<0.0001). Expression of LAT2, LAT3, ASCT2 expression was associated with better MFS (HR 0.85, 0.63, 0.74, p<0.0001-0.04). After multivariable adjustment, PSMA expression remained independently prognostic of poorer MFS (HR 1.3, p=0.028). Luminal B subtype was notable for PSMA overexpression; Luminal A was enriched in ASCT2 and LAT2 (p<0.0001). PSMA expression did not correlate with ERG fusion prostate cancers, but LAT2, ASCT1, and ASCT2 were overexpressed in ERG fusion negative tumors (p<0.0001). Conclusions: PSMA expression is associated with more aggressive disease and poorer clinical outcomes than fluciclovine transporter genes in localized prostate cancer. Molecular subtypes of prostate cancer vary in PSMA and fluciclovine transporter gene expression.

143 Background: Systemic treatment in the management of metastatic prostate cancer is inevitable. However, there is a growing interest in metastases-directed therapy (MDT). We sought to investigate the efficacy of MDT in treating patients with solitary metastatic prostate cancer and hence, delaying initiation of systemic treatment (i.e., Androgen deprivation therapy or chemotherapy). Methods: We retrospectively identified 61 patients treated with targeted therapy in the form of surgery (n = 30), stereotactic body radiation therapy (SBRT) (n = 25), or cryotherapy (n = 7) for their solitary metastases prostate cancer. Complete response was defined by achieving a PSA value of ≤0.2 ng/ml plus resolution of the solitary metastatic lesion on C-11 choline PET choline scan, while incomplete response was defined by a residual PSA of > 0.2 ng/ml and/or radiographic evidence of disease following metastases-targeted therapy. Results: Mean (±SD) age was 68.4 (±7.8) yrs., median (IQR) primary Gleason Score was 7 (7-9) and median (IQR) pre-MDT PSA was 2 (1.3-3.8) ng/ml. Median (IQR) time from primary treatment of the prostate to MDT was 5.1 (2.7-10.1) years. None of the patients were on hormone therapy at the time of presentation with solitary metastases prostate cancer. 30 patients had bone metastases, 29 patients had lymph node metastases, 1 patient had soft tissue metastasis (pelvic metastatic mass), and another patient had visceral metastasis (to the lung). 42% of the patients (n = 26) achieved complete response to targeted therapy. Median time to initiation of 2nd line systemic treatment following MDT was 17.8 months for the complete responders versus 9.3 months for incomplete responders. 11% of the patients (n = 7) did not require 2nd line therapy after their MDT for a mean (±SD) time of 56.9 (±22.5) months. Conclusions: The use of targeted therapy in the management of patients with solitary metastatic disease or low-volume metastatic disease can provide comparable outcomes to those of systemic treatment. Further studies are warranted.

AbstractBackgroundOptimal sequencing of systemic therapy in the management for metastatic castration resistant prostate cancer (mCRPC) remains poorly elucidated. The CHAARTED and STAMPEDE studies have proven that early chemotherapy in the hormone‐sensitive setting yields a greater net survival advantage than docetaxel for mCRPC. In a retrospective study, we attempt to investigate the two most common treatment sequences for mCRPC and investigate whether earlier chemotherapy for mCRPC is consequential to survival outcomes.MethodsWe identified 112 patients with mCRPC treated at the Mayo Clinic between 2011 and 2017. We identified two cohorts, 80 patients (group A) received full course docetaxel chemotherapy followed by second generation hormone therapy (2nd gen androgen deprivation therapy [ADT]; Abiraterone or Enzalutamide) and 32 patients (group B) treated with 2nd gen ADT followed by docetaxel. The primary endpoint evaluated was 3‐year cancer‐specific survival.ResultsMean prostate specific antigen at initiation of first treatment was 32.0 in group A and 21.7 in group B (P = .4). Bone metastases were more prevalent in group B (87% vs 58%, P = .01). All other clinicopathologic variables were statistically similar between group A and group B. Three‐year cancer‐specific survival was 87.4% vs 64.1% for group A and group B, respectively (P = .016). We report a univariate hazard ratio of 3.61 (95% CI, 1.74‐9.5, 0 P = .01). Three‐year overall survival was 82.4% and 60.8% for group A and group B, P = .01. These results held true when excluding patients with lymph node only metastasi.ConclusionOur data indicates that sequence of systemic therapy may influence outcomes for mCRPC and that docetaxel should be considered before 2nd generation ADT. Our results support the importance of earlier chemotherapy in the castration resistant state.

BackgroundThe progression of prostate cancer is a complex, multistep process that involves molecular alterations in cells of the tumor and the microenvironment, with associated interactions between the stroma and epithelium. Genomic expression analyses of stromal infiltration markers were performed to determine the significance thereof in prostate cancer.MethodsGenome‐wide expression profiles of formalin‐fixed, paraffin‐embedded radical prostatectomy samples were evaluated from a prospective registry cohort (n = 5239) and 3 retrospective institutional cohorts (n = 1135). Two independent stromal gene expression signatures implied stromal infiltration. Cox proportional hazards regression defined the association between stromal infiltration expression and metastasis‐free survival (MFS).ResultsStromal expression scores were correlated with stromal signature genes and with other key stromal markers (CAV1, VIM, and TAGLN), basal activity, and CD3 and CD4 immune biomarkers (r > 0.5 for all). The top decile of stromal expression was associated with high genomic risk scores (Decipher ≥ 0.6) , high Cancer of the Prostate Risk Assessment–Postsurgical scores, Gleason 9 to 10 disease, and a higher risk for metastasis (hazard ratio, 2.35; 95% CI, 1.37‐4.02; P = .001). A higher stromal infiltration score was also associated with decreased expression of DNA repair genes and higher radiation sensitivity genomic scores. Postoperative radiation therapy (RT) was associated with an MFS benefit for patients with high stromal scores, but not for patients with low stromal scores (Pinteraction = .02).ConclusionsExpression of stromal infiltration markers is correlated with prostate cancer aggressiveness/progression and may be predictive of a response to RT. Stromal infiltration markers should be studied and considered for incorporation into clinical prognostication and decision making.