Diamantopoulos, Leonidas Nikolaos

4580 Background: ICIs are used for UC in different settings. Most cases have pure urothelial carcinoma (PUC) but about a third have UC mixed with SH. We examined pts with UC treated with ICI and hypothesized that outcomes would not differ between PUC and mixed with SH. Methods: We retrospectively included pts with PUC and any SH component treated with ICI as adjuvant, 1st line [1L] upfront, maintenance avelumab [mAV], ≥2nd line [2+L] therapy; pts were divided by SH type. Pts with multiple SH were included as separate group. We excluded pts with pure non-UC histology and pts treated with neoadjuvant ICI. We calculated overall response rate (ORR), median overall, progression-free and disease-free survival [mOS, mPFS, mDFS] using KM method from ICI start. Analysis was stratified by therapy line; multivariable models were adjusted by Khaki factors for 1L/upfront, mAV and Bellmunt factors for 2+L; reference group was PUC. We used descriptive statistics for small subsets. Results: We included 1525 pts from 26 sites; n=752 1L, n=609 2+L; 76% men, 80% White, 69% smoking history, 80% lower urinary tract primary, 28% SH. Median f/u time from 1L ICI start 24 months (mo): mPFS was 3 (95%CI 2.8-3.2) mo for PUC (n=340), 3 (95%CI 2-4) mo for squamous (n=60) (HR=1, [95%CI 0.7-1.4]), 2 (95%CI 1.4-3.2) mo for micropapillary (n=36) (HR=1.3 [95% 0.9-2]) and 4 (3.5-4.5) mo for ≥2 SH (n=20) (HR=0.9 [95%CI 0.6-1.5]). Median f/u time from 2+L ICI start 26 mo: mPFS was 3 (95%CI 2.4-3.2) mo for PUC (n=264), 4 (95%CI 2-5) mo for squamous (n=33) (HR=0.8, [95%CI 0.6-1.2]), 3 (95%CI 1.6-3.7) mo for micropapillary (n=17) (HR=0.9 [95% 0.6-1.7]) and 3 (2.5-3.1) mo for ≥2 SH (n=10) (HR=1.2 [95%CI 0.6-2.2]); Table shows ORR/OS data. Data on adjuvant and mAV settings will also be presented. Conclusions: We found no significant survival difference between PUC and SH. ORR was numerically higher with sarcomatoid SH and ≥2 SH in the 1L upfront setting. Limitations: retrospective design, small sample size in a few subsets, lack of randomization and central scan/path (% SH) review, selection bias, unmeasured confounders. [Table: see text]

e16618 Background: Micropapillary urothelial carcinoma (MUC) is a rare variant of bladder cancer with limited prognostic data in the literature. We hereby present a novel prognostic model for overall (OS), for patients with MUC, derived from the Surveillance, Epidemiology and End Results (SEER) database. Methods: The SEER database (18 registries/November 2020) was queried with the case listing method by using the ICD-10 topography codes C67.0-C67.9 (bladder cancer), and the morphologic code 8131 (MUC). Patients were randomly divided into a training (TC) and a validation cohort (VC) (7:3 ratio). Variables significantly associated with OS were identified with multivariate Cox regression and backwards stepwise conditional approach; each variable received “points” according to its beta coefficient, based on the formula: Probability of an event at time t=S0(t)exp(β1x1, β2x2...), (β = regression coefficients, x = observed covariate values, S0(t) = survival function). Cumulative risk points were assigned to each patient and three distinct risk categories for OS were constructed. Harrel’s optimism-corrected C-statistic with bootstrap resampling was used for internal (TC) and external (VC) validation. Discriminatory performance of the model was compared to the AJCC 8th edition with the likelihood ratio test (LRT). Results: 548 patients were included in the study (374 TC, 174 VC). No statistically significant differences in baseline characteristics and survival outcomes were identified between TC and VC. Age, marital status, tumor size, AJCC stage, radical cystectomy, radiation and chemotherapy were significant variables inserted in the multivariate model. Patients were stratified to three risk groups (low, intermediate, high) based on the total risk points collected (<100, 100-150 and >150, Table). Median OS was NR (95%CI; NR, NR), 41 (95% CI; 25-57) and 14 months (95% CI; 11-17) for the low, intermediate, and high-risk categories respectively (log-rank p<.001). Optimism-corrected C-statistic for the prognostic score was 0.74 (95%CI;0.71-0.78) in the TC and 0.70 (95%CI; 0.65-0.78) in the VC. C-statistic for AJCC 8th edition was 0.65 (95% CI; 0.61-0.69) and 0.62 (95% CI; 0.56-0.68) in the TC and VC respectively. The LRT demonstrated superior discriminatory performance of our prognostic model compared to AJCC (p<.001). Conclusions: We present a novel prognostic model for OS of patients with MUC composed of clinicopathologic and treatment variables. Our model had superior performance to the AJCC system and may serve as a useful tool for individualized risk assessment in patients with MUC. [Table: see text]

695 Background: Small cell carcinoma of the bladder (SCCB) is a rare variant of bladder cancer with limited data informing prognosis. We present a novel prognostic model for disease specific survival (DSS) for patients with non-metastatic (M0) SCCB, derived from the Surveillance, Epidemiology and End Results (SEER) database. Methods: The SEER database (18 registries/November 2020) was queried with the ICD-10 topography codes C67.0-C67.9 (bladder), and the morphologic code 8041 (SCCB). Eligible patients (adults, histologic confirmation, available follow-up/staging data, M0) were randomly divided into a training (TC) and a validation cohort (VC) (7:3 ratio). Variables significantly associated with DSS were identified with multivariate Cox regression and backwards stepwise conditional approach and inserted in the model. Points were assigned to each variable based on the formula: Probability of an event at time t=S0(t)exp(β1x1, β2x2...), (β = regression coefficients, x = observed covariate values, S0(t) = survival function). Cumulative risk points were assigned to each patient and three distinct risk categories for DSS were constructed. Harrel’s C-statistic with bootstrap resampling was used for internal (TC) and external (VC) validation. Model performance was compared to the AJCC 8th edition (likelihood ratio test -LRT). Results: A total of 1039 patients were included (739 TC, 300 VC). No statistically significant differences in baseline characteristics/survival outcomes were identified between TC and VC. Age (years), T/N stage, radical cystectomy, chemotherapy, and radiation were significant variables inserted in the multivariate model (table). Patients were stratified to three risk groups (low, intermediate, high) based on the total cumulative risk points collected. Median DSS was NR (95%CI; NR, NR), 25 (95% CI; 18-32) and 9 months (95% CI; 7-11) for the low, intermediate, and high-risk category, log-rank p<.001. Harrel's C-statistic for the model was 0.70 (95%CI;0.67-0.73) in the TC and 0.66 (95%CI; 0.61-0.71) in the VC. In comparison, C-statistic for the AJCC 8th edition was 0.56 (95% CI; 0.52-0.59) and 0.53 (95% CI; 0.51 to 0.57), respectively. The LRT demonstrated superior performance of the model compared to AJCC (p<.001). Conclusions: We present a novel prognostic model for DSS in patients with locoregional SCCB composed of variables readily available in daily practice, which may serve as a useful tool for individualized risk assessment of patients with this rare malignancy. Further validation in prospective studies/clinical trials is warranted. [Table: see text]

654 Background: MSI and TMB correlate with ICI efficacy. We assessed the association between TMB and MSI with outcomes in pts with aUC treated with anti-PD1/L1 in a ‘real-world’ cohort. We hypothesize that pts with high TMB and MSI-high (H) have better outcomes with ICI. Methods: In this retrospective study we included pts from 13 sites treated with ICI for aUC. We calculated overall response rate (ORR), median overall and progression-free survival (mOS, mPFS) using KM method from ICI start. TMB and MSI were assessed by NGS. TMB was analyzed as dichotomous (≥10 vs <10 mut/Mb) and continuous variable. The analysis was stratified by therapy line (1L/upfront, 2+L). Multivariable models were adjusted by Khaki factors for 1L/upfront and Bellmunt factors for 2+L. We separately analyzed pts on maintenance avelumab (mAV). MSI is reported with descriptive statistics only. Results: 342 pts were treated with ICI 1L/upfront or 2+L (69% pure UC, median age at ICI start 69, 77% men, 90% White, 16% upper tract primary, 12% liver metastases [mets], 78% ECOG PS 0-1). Median f/u from ICI start was 34 months (mo). ORR was 36% (95%CI 26-46%) in pts with TMB≥10 vs 30% (95%CI 23-36%) with TMB<10 (OR=1.4 [95%CI 0.8-2.5] p=0.3). ORR was 75% (6/8) in pts with MSI-H and 30% (60/200) with MSI stable (MSI-S). mPFS was similar between TMB≥10 and <10 groups (6 vs 4 mo; HR=0.88 [95%CI 0.61-1.26] p=0.48) and between MSI-H and MSI-S (5 mo). mOS was numerically longer (not significant) in pts with TMB≥10 vs TMB<10: 25 vs 21 mo; (HR=0.7 [95%CI 0.50-1.09] p=0.12) and with MSI-H and MSI-S (NR and 20 mo). A significant association was found between TMB (continuous variable) and OS (HR=0.97 [95%CI 0.95-0.99] p=0.01). TMB analyses by therapy line are shown in Table. In the 1L/upfront setting (N=144), ORR 71% (5/7) vs 33% (45/135), mPFS 5 and 4 mo, mOS NR and 22 mo for MSI-H and MSI-S, respectively. Pts on mAV (n=77) were 77% men, 92% White, 16% upper primary, 13% liver mets, 84% ECOG PS 0-1 with median f/u 15 mo from avelumab start; mOS was NR for MSI-H and 24 mo for MSI-S; mPFS was 4 mo for both groups. Of 3 pts on mAV with MSI-H: 1 CR, 2 SD; of 58 pts with MSI-S: 4CR, 4PR, 24 SD, 21 PD, 5 unknown. Conclusions: MSI-H had numerically higher ORR and higher TMB was associated with longer OS with ICI, but further validation is needed. Limitations: retrospective design, small sample size for MSI-H cases, lack of randomization and central scan review, selection/confounding. [Table: see text]

There is an evolving landscape of systemic combination regimens for patients with advanced well-differentiated gastroenteropancreatic neuroendocrine tumors (GEP-NETs). In this review, we provide a comprehensive outline of the existing clinical trials/prospective studies investigating these combinations. PubMed was searched using key relevant terms to identify articles referring to GEP-NETs and combination treatments. No systematic search of the literature or metanalysis of the data was performed, and we focused on the most recent literature results. Primarily, phase 1 and 2 clinical trials were available, with a smaller number of phase 3 trials, reporting results from combination treatments across a wide range of antiproliferative agents. We identified significant variability in the anti-tumor activity of the reported combinations, with occasional promising results, but only a very small number of practice-changing phase 3 clinical trials. Overall, the peptide receptor radionuclide therapy (PRRT)-based combinations (with chemotherapy, dual PPRT, and targeted agents) and anti-vascular endothelial growth factor (VEGF) agent combinations with standard chemotherapy were found to have favorable results and may be worth investigating in future, larger-scale trials. In contrast, the immune-checkpoint inhibitor-based combinations were found to have limited applicability in advanced, well-differentiated GEP-NETs.

Abstract Background Patients with inflammatory bowel disease (IBD) have low vaccination rates for vaccine-preventable diseases. Fear of adverse reactions (AEs) appear to negatively affect vaccination efforts. We aimed to systemically review the risks for AEs following immunization for patients with IBD. Methods We searched PubMed and Embase until April 15, 2020, for studies evaluating the safety of vaccinations among patients with IBD. The primary outcome was the incidence of systemic and local AEs among vaccinated patients. Secondary outcome was the rate of IBD flare following immunization. We utilized a random effects meta-analysis of proportions using the DerSimonian-Laird approach to estimate the safety of immunizations. Results A total of 13 studies with 2116 patients was included in our analysis after fulfilling our inclusion criteria. Seven studies examined the influenza vaccine, 4 the pneumococcal vaccine, 1 the recombinant zoster vaccine, and 1 the hepatitis B vaccine. Follow-up of patients was up to 6 months. The majority of AEs were local, with a pooled incidence of 24% (95% CI, 9%-42%) for all vaccines. Systemic AEs were mostly mild, without resulting in hospitalizations or deaths, with a pooled incidence of 16% (95% CI, 6%-29%) for all vaccines. Flare of inflammatory bowel disease after vaccination found with a pooled incidence of 2% (95% CI, 1%-4%) and we include in the analysis data from all immunizations examined. Discussion Our study demonstrated that AEs after vaccination are mainly local or mildly systemic and do not differ significantly from the expected AE after recommended immunizations for the general population. Thus, gastroenterologists should reinforce that vaccines are safe in patients with IBD.

Objectives To evaluate outcomes of patients achieving a post‐treatment pathological stage of <ypT2N0 at radical cystectomy (RC) following neoadjuvant chemotherapy (NAC) for muscle‐invasive bladder cancer (MIBC) to identify an optimal definition of pathological response. Patients and Methods Patients from 10 international centres who underwent NAC for cT2–4aN0–1 MIBC and achieved <ypT2N0 disease at RC were included. The primary outcome was time to recurrence, either local or distant. Kaplan–Meier and Cox proportional hazards regression were used to evaluate associations between clinicopathological variables and outcomes. Results A total of 625 patients were included. The median age was 66 years and 80% were male. Gemcitabine and cisplatin (GC, 56%) and methotrexate, vinblastine, doxorubicin and cisplatin (MVAC)/dose‐dense (dd)MVAC (32%) were the most common NAC regimens. ypT0, pure ypTis, ypTa ±ypTis and ypT1 ± ypTis were attained in 58.1%, 20.0%, 7.6% and 14.2% of patients, respectively. The cumulative incidence of recurrence at 5 years was 9%, 16%, 29% and 30%, respectively. Pathological stage was prognostic for recurrence, with ypTa ± Tis (hazard ratio [HR] 3.20, 95% confidence interval [CI] 1.40–7.30) and ypT1 ± Tis disease (HR 4.03, 95% CI 2.13–7.63) associated with a significantly higher recurrence risk. Pure ypTis (HR 1.66, 95% CI 0.82–3.38) and the type of NAC regimen (ddMVAC: HR 1.59, 95% CI 0.55–4.56; MVAC: HR 1.18, 9%% CI 0.25–5.54; reference: GC) were not associated with recurrence. Conclusion We propose that optimal pathological response after NAC be defined as attainment of ypT0N0/ypTisN0 at RC. Patients with ypTaN0 or ypT1N0 disease (with or without Tis) at RC displayed a significantly higher risk of recurrence and may be candidates for trials investigating adjuvant therapy.

5043 Background: Pathologic complete response (pCR) after NAC for MIBC is strongly correlated with long-term overall survival. However, there are sparse data on the risk of recurrence based on depth of pathologic response (pT0, pTa, pTis, pT1), and the differential impact of clinicopathologic factors and NAC regimen on recurrence. Methods: Baseline data on all pts with cT2-4N0-1 MIBC receiving NAC and who achieved < ypT2N0 disease at radical cystectomy (RC) from 9 international centers were obtained. The key outcome was time to recurrence (TTR) – defined as the time to any recurrence in the urinary tract or regional/distant metastasis, with death (in the absence of recurrence) considered a competing risk. Cox regression analysis was used to analyze the impact of clinical factors on recurrence. Results: A total of 506 pts were available. Median age was 66 years (range 33-86) and 78% (n = 396) were male; median follow-up after RC was 2.6 years. The majority of patients had pure urothelial histology (n = 371, 73%), and baseline stage was cT2N0 (n = 368, 73%), cT3-4N0 (n = 95, 19%) and TanyN1 (n = 43, 9%). NAC regimens were gemcitabine-cisplatin (GC, n = 296, 59%), dose-dense methotrexate-vinblastine-doxorubicin-cisplatin (ddMVAC, n = 141, 28%), split-dose GC (n = 29, 6%), MVAC (n = 29, 6%) and non-cisplatin based regimens (n = 11, 2%). At RC, 304 patients (60%) had ypT0N0 disease, 32 (6%) had ypTaN0, 107 (21%) had ypTisN0 and 63 (13%) had ypT1N0. Overall, 43 patients (8%) recurred with a median TTR of 56 weeks (range 7-251); 5-year freedom from recurrence was 87% (95% CI 83-91). The majority (n = 38) recurred outside the urinary tract. On multivariable analysis, ypTa (HR = 3.36 [1.24-9.11]) and ypT1 (HR = 2.88 [1.33-6.22], p = 0.013) disease at RC were predictors of shorter TTR, while female sex was associated with longer TTR (HR = 0.52 [0.27-0.98], p = 0.043). The type of NAC was not predictive of TTR (GC vs. other, HR = 1.49 [0.75-2.97], p = 0.26). Conclusions: To our knowledge, this is the largest study to quantify the risk of recurrence in pts achieving pathologic response after NAC and RC for MIBC. 8% of patients undergoing NAC and achieving < ypT2N0 at RC recurred. Residual ypTa and ypT1 disease conferred a significantly higher risk of recurrence, while ypTis did not; female sex was associated with a lower risk of recurrence. Importantly, the type of cisplatin-based NAC regimen used was not an independent predictor of recurrence.