Citations

5083 Background: ARASENS and PEACE-1 trials suggests treatment intensification with novel hormonal therapy (NHT) in addition to androgen deprivation therapy (ADT) and docetaxel (DOC) provides survival benefit as compared to DOC+ADT in patients with metastatic castration sensitive prostate cancer (mCSPC). However, the performance of triplet therapy as compared to NHT+ADT remains unexplored. Methods: MEDLINE, EMBASE and recent conference proceedings were searched to include phase III trials evaluating triplet therapy in patients with mCSPC and reporting treatment effects in subgroup of patients with and without docetaxel. Outcomes included overall survival (OS) and radiographic progression free survival (rPFS). Precomputed hazard ratios (HRs) and confidence intervals (CIs) from non-randomized subgroup comparisons were pooled after logarithmic transformation using inverse-variance weighting approach. A DerSimonian-Laird random-effects meta-analysis was then performed to assess subgroup differences. Interaction between subgroups was assessed using P-value of heterogeneity. Mixed treatment comparisons were computed using a fixed-effect model within the frequentist framework using subgroup effect estimates from eligible trials. Results: This meta-analysis included five clinical trials (ARASENS, PEACE-1, ENZAMET, ARCHES and TITAN) with a total of 5804 patients (docetaxel: 2836; no docetaxel: 2836). Subgroup analysis showed statistically significant difference between treatment effects in patients who received docetaxel (NHT + DOC + ADT; HR: 0.74; 95% CI: 0.66-0.84; I2: 0%) and those who did not (NHT + ADT; HR: 0.61; 95% CI: 0.53-0.70; I2: 0%) for OS (p-value of interaction: 0.04). However, no statistically significant interaction was observed in terms of rPFS (p-value: 0.46). Mixed treatment comparisons showed improved OS with NHT + DOC + ADT (HR: 0.74; 95% CI: 0.66-0.84) as compared to DOC + ADT, but not when compared to NHT + ADT (HR: 0.97; 95% CI: 0.78-1.20). NHT + ADT significantly improved OS compared to DOC + ADT (HR: 0.77; 95% CI: 0.64-0.92). Consistently, significant rPFS improvement was observed with NHT + DOC + ADT when compared DOC + ADT (HR: 0.49; 95% CI: 0.42-0.57) but not when compared to NHT + ADT (HR: 0.82; 0.65-1.04). NHT + ADT was observed to improve rPFS compared to DOC + ADT (HR: 0.60; 95% CI: 0.50-0.72). Conclusions: This exploratory and hypothesis generating analysis suggests that addition of docetaxel (triplet therapy) may not delay progression or prolong survival compared to NHT-based doublets. These findings provide direction for future clinical trials in this space and suggest an equipoise to the question of how triplet regimens compare with NHT-doublets. The results should be interpreted with caution as this analysis does not account for potential confounding relationships such as volume of disease.

e16550 Background: Improved computational power and modern algorithms have generated significant interest in radiomics for cancer diagnosis and staging. Here we assess the performance of deep learning (DL) models as a means for feature extraction in combination with supervised machine learning (ML) algorithms for accurate staging and chemotherapy response assessment of bladder cancer. Methods: Deidentified grayscale CT images from bladder cancer patients scheduled to undergo radical cystectomy were included in this retrospective study. These images were manually annotated with two regional masks (normal region and cancer region). Five DL models- namely, AlexNet, GoogleNet, InceptionV3, ResNet-50, and XceptionNet pre-trained on the ImageNet dataset, a public dataset, were then fine-tuned on our bladder CT scan data to extract features. Through feature selection process, the subset of the features was used to build ML classifiers for classification. The classification was performed using five different ML classifiers, namely k-Nearest Neighbor (KNN), Naïve-Bayes (NB), Support Vector Machine (SVM), Linear Discriminant Analysis (LDA), and Decision Tree (DT). The classification task was performed with 10-fold cross-validation, and each of the experiments contained a different but not mutually exclusive subset of samples. The evaluation metrics include accuracy, sensitivity, specificity, precision, and F1-score. Results: A total of 200 deidentified grayscale CT images of 100 patients with histologically proven bladder cancer, were included in this study. For experiment (1) normal vs. cancer, the LDA classifier on XceptionNet based features provides the best performance with an accuracy of 86.07%, sensitivity of 96.75%, specificity of 69.65%, precision of 83.07%, and F1-score of 89.39%. For experiment (2) non-muscle invasive Cancer (NMIBC) vs. muscle invasive bladder cancer (MIBC), the LDA classifier on XceptionNet based features provided the best performance with an accuracy of 79.72%, sensitivity of 66.62%, specificity of 87.39%, precision of 75.58%, and F1-score of 70.81%. For experiment (3) T0 lesion vs. MIBC, the LDA classifier on XceptionNet based features provides the best performance with an accuracy of 74.96%, sensitivity of 80.51%, specificity of 70.22%, precision of 69.78%, and F1-score of 74.73%. Conclusions: Our proposed model has shown good results in differentiating normal vs cancer and promising performance in differentiating T0 vs MIBC after chemotherapy treatment. We are expanding our dataset to further improve the performance in differentiating T0 vs MIBC. In addition, we will investigate the applicability of GAN for data augmentation to address data limit. We believe the hybrid DL and ML framework may facilitates radiologists' decisions and clinical decision-making in patients with bladder cancer.

4594 Background: Cisplatin based neoadjuvant chemotherapy (NAC) followed by definitive therapy improves survival in patients with muscle invasive bladder cancer (MIBC). However, the clinical benefit of NAC might vary with the choice of definitive therapy. Therefore, we assessed the absolute benefit of NAC followed by radical cystectomy or radical radiotherapy separately using the totality of evidence. Methods: MEDLINE and EMBASE were systematically searched to identify randomized trials assessing cisplatin based neoadjuvant chemotherapy followed by either radical cystectomy or definitive radiotherapy in patients with MIBC. Outcomes of interest included overall survival (OS) and disease-free survival (DFS). Treatment effects were expressed as hazard ratios (HR) with 95% confidence interval (CI). Incidence rate ratios were calculated to estimate time to event outcomes for trials not reporting HR. A random-effects DerSimonian-Laird meta-analysis was conducted. Absolute effects were then obtained using baseline risks from the control arm of RCTs. Results: Of 4887 studies identified, 13 trials with 2529 patients were included in this meta-analysis. Most trials included patients with T2-4 and N0 patients and only 3 trials included patients with node positive disease. Total of 180 (47%) DFS events were observed with NAC+RC compared to 213 (56%) events in RC alone (HR: 0.72; 95% CI: 0.59-0.89) and 346 (58%) OS events were observed with NAC+ RC compared to 385 (52%) events in RC alone (HR: 0.80; 95% CI: 0.69-0.92). Total of 186 (70%) DFS events were observed with NAC + radiotherapy compared to 205 (71%) events in radiotherapy alone (HR: 0.91; 95% CI: 0.74-1.12) and 263 (58%) OS events were observed with NAC+ radiotherapy compared to 294 (61%) events in radiotherapy alone (HR:0.93; 95% CI: 0.79-1.08). Conclusions: The choice of definitive therapy after cisplatin-based NAC impacts survival in patients with MIBC. RC after NAC improved DFS (114 fewer events per 1000 events) and OS (76 fewer per 1000 events) whereas radiotherapy after NAC showed no survival benefit. [Table: see text]

518 Background: Cisplatin (C) based neoadjuvant chemotherapy (NAC) has been the mainstay treatment for muscle invasive bladder cancer (MIBC). However, the optimal choice of NAC is not well-established. We therefore conducted a network-meta-analysis (NMA) to assess comparative efficacy of different treatment options. Methods: Several electronic databases (MEDLINE, and EMBASE) and conference proceedings were systematically used to identify randomized trials evaluating first-line treatments in neoadjuvant MIBC. Outcomes of interest included overall survival (OS), progression-free survival (PFS), objective response rate (ORR) and pathologic complete response (pCR). DerSimonian-Laird random-effects meta-analysis was used to compute direct comparisons between NAC and local therapy (LT) only. Fixed effect NMA was conducted within the frequentist framework for mixed treatment comparisons. P-scores were used to assess relative treatment rankings. All statistical analyses were conducted in R (v 4.1.1). Results: This systematic review included 23 trials (25 references) with a total of 5313 patients with 10 unique treatments. Direct comparisons showed significant benefit in PFS (HR: 0.82; 95% CI: 0.71-0.94), and in OS (HR: 0.85; 95% CI: 0.78-0.92) with NAC when compared to LT only. However, the likelihood of achieving an objective response (RR: 1.18; 95% CI: 0.72-1.95: I2: 85%) or CR (RR: 1.51; 95% CI: 0.87-2.61; I2: 79%) was not different between the two arms. Data available in 15 trials contributed to the network for PFS outcome while only eight trials contributed to OS outcome. Mixed treatment comparisons showed significantly improved PFS with nintedanib-gemcitabine-cisplatin (NinGC; HR: 0.42; 95% CI: 0.20-0.87) and dose-dense-methotrexate-vinblastine-doxorubicin-cisplatin (ddMVAC; HR: 0.61; 95% CI: 0.43-0.88) compared to LT only. Consistent benefit was observed when NinGC (HR: 0.48; 95% CI: 0.24-0.97) and ddMVAC (HR: 0.70; 95% CI: 0.51-0.96) were compared to GC only. However, no significant differences were observed between NinGC (rank 1) and ddMVAC (rank 2) or among other mixed treatment comparisons. Similarly, OS was significantly improved with NinGC (rank 1) relative to MVAC (HR: 0.41; 95% CI: 0.17-0.97), MVC (HR: 0.37; 95% CI: 0.16-0.88), MC (HR: 0.38; 95% CI: 0.16-0.92), AC (HR: 0.36; 95% CI: 0.15-0.91), and GC (HR: 0.39; 95% CI: 0.17-0.90). While similar results were observed with ddMVAC (rank 2) when compared to MVC (HR: 0.63; 95% CI: 0.42-0.94), MC (HR: 0.64; 95% CI: 0.42-0.98), and GC (HR: 0.66; 95% CI: 0.47-0.92), no significant differences were observed with ddMVAC when compared to MVAC (HR: 0.62; 95% CI: 0.38-1.01) and NinGC (HR: 1.70; 95% CI: 0.69-4.19). Conclusions: Current evidence shows improved PFS and OS with the use of neoadjuvant ddMVAC and Nin-GC in patients with MIBC relative to other treatment options.

360 Background: Pembrolizumab has been established as an effective treatment option in adjuvant renal cell carcinoma after the publication of KEYNOTE-564. However, the magnitude of benefit based on different risk categories is not well defined. Methods: We included full-text publications of phase II/III randomized controlled trials (RCTs) evaluating immune checkpoint inhibitors or tyrosine kinase inhibitors (TKIs) in adjuvant renal cell carcinoma after a systematic search. The outcomes of interest included disease free survival (DFS), overall survival (OS), all grade or grade ≥3 treatment related, and all cause adverse events. Mixed treatment comparisons were computed through a fixed-effect multivariate meta-regression within the frequent framework. Relative treatment rankings were assessed using P-scores. We used stratified baseline risks of disease progression from observational data and at 5, 10, 15 years from the Leibovich risk stratification system (based on risk scores ranging from 0 to ≥15). Corresponding intervention risks (CIRs) were then approximated using relative effect estimates (from NMA) and baseline risks. The difference between CIRs and baseline risks were calculated to present absolute risk differences in each baseline category. Results: This NMA included six RCTs with a total of 7525 participants and five unique treatment options. Mixed treatment comparisons showed significant DFS and OS benefit with pembrolizumab (rank 1) when compared against sunitinib (DFS HR 0.74 [0.55-0.99]; OS HR 0.51 [0.27-0.94]). However, there were no significant differences with pembrolizumab compared to pazopanib (DFS HR 0.81 [0.60- 1.09]; OS HR 0.54[0.29-1.01]) and axitinib (DFS HR 0.78 [0.54-1.14]; OS HR 0.52 [0.24-1.16]). The safety profiles were comparable. Absolute benefit of TKIs in adjuvant setting was minimal whereas this benefit increased with higher T and N patients in patients treated with pembrolizumab (Table). Similarly, the treatment benefit increased with higher Leibovich’s risk scores at 5, 10 and 15 years of follow up. Conclusions: The current analysis suggests that a risk adapted approach may be useful when considering adjuvant pembrolizumab in RCC patients.[Table: see text]

136 Background: Intensification of initial treatment of in patients with metastatic castration-sensitive prostate cancer (mCSPC) with androgen pathway inhibition (API) in addition to docetaxel (DOC) and androgen deprivation therapy (ADT) has shown promise to improve clinical outcomes. Thus, we synthesize the data from modern clinical trials to estimate overall estimates of progression and survival outcomes. Methods: A systematic search of electronic databases (MEDLINE and EMBASE) was conducted to include phase III randomized controlled trials (RCTs) evaluating triplet therapy (API+DOC+ADT) against doublet therapy (DOC+ADT) in mCSPC. Outcomes of interest included overall survival (OS) and radiographic progression-free survival (rPFS). A DerSimonian-Laird random-effects meta-analysis was performed to pool precomputed hazard ratios (HRs) and confidence intervals (CIs) after logarithmic transformation using inverse-variance weighting approach. Cochran’s Q statistical test was used to assess statistically significant heterogeneity not explained by chance, while I2 statistical test was used to quantify the total observed variability, due to between-study heterogeneity. I2 values >50% indicated substantial heterogeneity. A summary of findings table was constructed to translate relative estimates to absolute risks. Results: A total of 1,531 patients in four RCTs with direct comparative data between triplet and doublet therapies, were included in this meta-analysis. PEACE-1 was the only RCT directly assessing this question (AAP+DOC+ADT). ENZA+DOC+ADT was evaluated as a subgroup in two RCTs (ENZAMET; ARCHES), APA+DOC+ADT was evaluated as a subgroup in one (TITAN). To be able to pool studies, the relative efficacy of control arm in ENZAMET (first generation bicalutamide + ADT) was considered equivalent to ADT based on prior literature. A total of 672 rPFS events were observed (34%; 261 events in triplet therapy, 54%; 411 events in doublet therapy). The difference was statistically significant (HR: 0.49; 95% CI: 0.42-0.58; I2: 0%). Similarly, 469 OS events were observed (28%; 217 events in triplet therapy, 33%; 252 events in doublet therapy). The difference was statistically significant (HR: 0.80; 95% CI: 0.67-0.96; I2: 0%). The summary of findings is outlined in the table. Conclusions: The results of this meta-analysis support an improvement in rPFS and OS in favor of triplet therapy over doublet therapy for mCRPC. However, comparative effectiveness of different triplet regimens may be different and needs further exploration.[Table: see text]

134 Background: Recent trials have suggested poly ADP-ribose polymerase inhibitors (PARPi) sensitivity in patients with treatment-refractory metastatic castration-resistant prostate cancer (mCRPC) harboring mutations in DNA damage and response repair genes (DDR). However, the efficacy profile might differ with different genes and is still being explored in multiple studies. Methods: We systematically searched several electronic databases (MEDLINE, EMBASE), and conference proceedings to include abstracts and full-text publications of phase II/III trials evaluating PARPi in treatment-refractory mCRPC with DDR gene alterations. Outcomes of interest included objective response rate (ORR), complete response (CR), prostate specific antigen (PSA) 50% response, circulating tumor cells conversion (CTCc) from ≥ 5 to < 5 cells, composite response (CoR) and risk of progression. Data was pooled using Inverse-variance approach. A DerSimonian and Laird random-effect meta-analysis was conducted to estimate pooled proportion (PP) of events using the Freeman-Tukey transformation in each gene. Clopper-Pearson method was used to estimate the associated 95% confidence intervals (CI). Results: This systematic review and meta-analysis included five unique trials with 648 patients and four PARPi (niraparib, olaparib, rucaparib, talazoparib). Objective response to PARPi was observed in 44.7% of patients with mutations in either BRCA1 or 2 or both (95% CI: 36.0%-53.6%; I2: 0%), 23.5% with ATM (95% CI: 3.91%-51.0%; I2: 65%), 25.0% with CDK12 (95% CI: 8.66%-49.1%), and 45.3% with PALB2 alterations (95% CI: 14.8%-77.5%; I2: 0%). Consistent results were observed for CR outcome. PSA50% response to PARPi was observed in 60.3% of patients with BRCA1/2 mutations (95% CI: 50.3%-70.0%; I2: 57%), 5.54% (95% CI: 0.01-16.6; I2: 0%) with ATM, and 70.1% (95% CI: 35.6%-96.6%; I2: 0%) with PALB2 mutations while no PSA 50% response was observed in patients with CDK12 mutations (PP: 0.00%; 95% CI: 0%-16.84%). Moreover, CTCc was observed in 68.3% of patients with BRCA1/2 mutations (95% CI: 45.0%-87.8%; I2: 77), 34.2% (95% CI: 11.2-61.3%; I2: 45%) with ATM, 41.7% (95% CI: 15.2%-72.3%) with CDK12, and 48.5% (95% CI: 6.39%-92.9%; I2: 49%) with PALB2. CoR was observed in 76.5% patients with BRCA1/2 mutations (95% CI: 65.4%-86.1%; I2: 22%), 30.4% (95% CI: 16.0%-46.9%) with ATM, 25% (95% CI: 8.66%-49.1%) with CDK12, and 63.9% (95% CI: 31.0%-91.8%; I2: 0%) with PALB2 mutations. Similarly, the risk of progression was 50.9% in patients with BRCA1/2 mutations (95% CI: 37.7%-63.9%), 70.9% (95% CI: 60.0%-80.40%; I2: 0%) with ATM, and 75% (95% CI: 19.4-99.3%) with PALB2. Conclusions: Current evidence is sparse regarding efficacy by specific genes. Limited data favors the use of PARPi in mCRPC patients harboring mutations in BRCA1/2 and PALB2 genes.

132 Background: Treatment landscape for metastatic castration-sensitive prostate cancer (mCSPC) is rapidly evolving. Recent updates of relevant trials and presentation of PEACE-1 results warranted mixed treatment comparisons to inform the choice of treatment in mCSPC. Methods: MEDLINE and EMBASE, along with conference proceedings were searched using a systematic search strategy to identify relevant abstracts and full-text publications of phase II/III randomized controlled trials (RCTs) assessing first-line treatment options in mCSPC. Outcomes of interest included overall survival (OS), radiographic progression-free survival (rPFS), and grade ≥3 adverse events (AEs). Direct comparisons were made using DerSimonian-Laird random-effects meta-analysis. Fixed-effect frequentist NMA was conducted to compute network estimates using a multivariate meta-regression approach. Relative treatment rankings were assessed in congruency with direct estimates using P-scores. Secondary NMAs were conducted in several substrata (young, and old; Gleason score < 8 and ≥8; performance status 0 and 1-2, low and high volume of disease). Results: This NMA included nine trials (23 references) with nine unique treatments. rPFS was improved with abiraterone acetate and prednisone-docetaxel-androgen deprivation therapy combination (AAP-D-ADT; rank 1) when compared against most treatment options including AAP-ADT (HR: 0.58, 95% CI: 0.44-0.76; rank 5), apalutamide (APA)-ADT (HR: 0.63, 95% CI: 0.46-0.87; rank 4), TAK-ADT (HR: 0.55, 95% CI: 0.36-0.84; rank 6), and enzalutamide(E)-AAP-ADT (HR: 0.70, 95% CI: 0.51-0.97; rank 3), however no significant differences were observed between AAP-D-ADT, and E+ADT (rank 2). Improved OS was observed with AAP-D-ADT (HR: 0.75, 95% CI: 0.59-0.95; rank 2), E-AAP-ADT (HR: 0.68; 95% CI: 0.48-0.97; rank 1), and AAP-ADT (HR: 0.82, 95% CI: 0.70-0.96; rank 3) compared to D+ADT (rank 6). However, most of the mixed treatment comparisons were statistically insignificant in terms of OS. Similarly, in patients with high volume of disease, AAP+D+ADT (rank 1) was observed to significantly improve rPFS compared to AAP-ADT, APA-ADT, E-ADT, and D-ADT; however, no significant differences were observed among treatment comparisons with regards to OS improvement. E+ADT (rank 1) improved rPFS compared to other treatment in low volume disease but was not different for OS. No significant differences were observed among different treatment options when compared across prespecified subgroups. Moreover, AAP+D+ADT was ranked as the least safe with significantly increased risk of grade 3 AEs relative to other treatments. Conclusions: Current NMA suggests that triplet therapy options were ranked as most likely to improve rPFS and OS at the cost of increased toxicity. Doublet combinations may still be preferred for older patients with low volume of disease.

26 Background: The underrepresentation of minority populations in clinical trials negatively impacts cancer and widens inequities. We aimed to quantify the enrollment disparities in prostate cancer (PC) clinical trials over the last three decades. Methods: MEDLINE and Embase were searched to identify primary reports of prostate cancer RCTs (1989-2020). Data for trial characteristics, the proportion of trials reporting race, ethnicity and age, and the proportion of patients by race, ethnicity and age enrolled in trials were summarized using descriptive statistics. Enrollment incidence ratios (EIR), which compare trial enrollment against global estimates of incidence in age-related subgroups (acquired from the Global Burden of Disease database) and U.S. population-based estimates of racial/ethnic subgroups (acquired from the SEER 18 incidence database) were calculated. Individual trial EIRs were pooled using random-effects meta-analyses to account for the substantial heterogeneity between trials. Multivariable meta-regression was used to explore associations between key trial characteristics and EIR. Annual percentage changes (APC) over the last three decades in enrollment disparities were analyzed using the Joinpoint Regression Analysis. Results: 281 trials from 1989 to 2020 with 99,588 patients were included in this analysis. 107 trials reported race (38%), of which only 25 trials (9%) reported data on all 5 U.S. racial categories (Black, White, Asian, Pacific Islander and Native American. 255 (91%) trials reported mean or median but only 71 trials (25%) specifically reported the enrollment proportion of older adults (age > 65 years). Clinical outcomes by race and age were reported in 9 (8%) and 37 (14%) trials, respectively. Results from meta-analyses showed that Black patients (summary EIR: 0.42 [95% CI: 0.35 - 0.51]), Hispanics (summary EIR: 0.50 [95% CI: 0.37 - 0.68]) and older adults (summary EIR: 0.95 [95% CI: 0.91 - 0.99]) were underrepresented in trials relative to their population estimates. Significantly fewer Black participants (EIR for Black patients = 0.42, EIR for White patients = 0.99; p < 0.0001), Hispanic participants (EIR for Hispanics = 0.50, EIR for non-Hispanics = 1.00; p = 0.001) and older adults (EIR for older adults = 0.95, EIR for younger adults = 1.06; p = 0.037) were enrolled. Representation of Black patients decreased significantly from 1989-2019 (APC: -4.25), while Hispanic representation increased significantly from 2000-2020 (APC: 5.89). Meta-regression showed Black patients were particularly underrepresented in larger-size trials (p < 0.0001). Conclusions: Black representation in PC clinical trials is less than 50% of their expected share based on cancer incidence and it has consistently decreased over last three decades, contributing to the disparities experienced by the population.