Prognostic value of integrated liquid biopsies in patients (pts) with metastatic urothelial cancer (mUC)

547

Background: Despite recent therapeutic advancements for patients with mUC, including checkpoint inhibitors (CPIs), anti-FGFR and antibody-drug conjugates (ADCs), biomarker data to predict therapeutic response and identify mechanisms of resistance remain limited. Ongoing randomized clinical trials evaluating the combination of CPIs and ADCs in these pts underscore the need to develop biomarkers to better understand who might best respond to these therapies. Here, we employ a liquid biopsy approach to molecularly characterize circulating tumor cells (CTCs) and circulating tumor DNA (ctDNA), including those isolated with Trop-2, the target of the novel drug Sacituzumab Govitecan and Datopotamab Deruxtecan. Methods: 104 blood samples serially collected from pts being treated for mUC were used for CTC collection using anti-EpCAM and Trop-2 antibodies in parallel. CTCs were isolated and stained for immune markers PD-L1 and HLA I using the VERSA (Versatile Exclusion-based Rare Sample Analysis) platform. Plasma was isolated for paired analysis of CTC and ctDNA content. CTCs were analyzed for enumeration and single-cell protein analysis. Overall survival (OS) was defined from time of sample collection, and survival analyses were performed using the Kaplan-Meier method. Results: We observed significantly shorter OS in pts with higher CTC burden (≥ 20 CTCs/7.5 mL blood) in samples captured with either EpCAM (median 34.1 vs 3.1 mo, P < 0.01) or Trop-2 (median 34.1 vs 6.2 months, P < 0.01). Furthermore, EpCAM and Trop-2 CTC burdens were higher at progression timepoints relative to responding or stable timepoints, when stratified according to treatment modality (table). Inter and intra-patient heterogeneous PD-L1 and HLA I expression and co-expression was observed on CTCs although no significant differences were seen globally between EpCAM and Trop-2 CTCs. In a cohort of pts treated with CPIs, we observed dynamic phenotypic changes in the ratio of HLA:PD-L1 that differed between EpCAM and Trop-2 CTCs. ctDNA analysis identified concordant increases in tumor fraction and acquired genomic mutations. When examined longitudinally across individual pts, these findings in tandem with changes in enumeration, suggest the emergence of different CTC subpopulations that may serve as biomarkers of resistance. Conclusions: We identify the prognostic significance of CTC enumeration with parallel EpCAM and Trop-2 CTC isolation and demonstrate the utility of a liquid biopsy assay that can detect pharmacodynamic changes in CTC burden and immune marker expression throughout the course of treatment. [Table: see text]

Assessing treatment preferences among patients with advanced/metastatic renal cell carcinoma in the United States: A discrete choice experiment

630

Background: The introduction of immunotherapies has changed the first-line treatment landscape for advanced/metastatic renal cell carcinoma (aRCC). This study examines patient preferences in this rapidly changing environment to better understand the tradeoffs patients with aRCC are willing to make when choosing treatment. Methods: Patients with self-reported aRCC in the United States completed an online, cross-sectional survey. A discrete choice experiment was used to assess preferences for attributes of aRCC treatments. Patients completed a series of choice tasks showing 2 treatment profiles that varied in 7 important attributes identified through literature and qualitative research: overall survival, progression-free survival (PFS), objective response rate (ORR), duration of response (DOR), risk of adverse events, quality of life (QOL) changes, and treatment administration. Descriptive statistics were reported, and a hierarchical Bayesian logistic model was used to calculate preference weights. Relative importance estimates (mean ± standard error) were computed for each attribute; these represent the mean percentage of the variation in preferences explained by the attribute. Results: Survey results from a total of 299 patients were analyzed (male, 50%; mean age, 56 years). All 7 attributes were statistically significant for influencing the choice of treatment. Key attributes included treatment regimen convenience and QOL improvement, which ranked similarly to increasing survival time. Among the efficacy attributes, increasing survival time was most important, followed by ORR, PFS, and DOR. Reducing the risk of serious adverse events from 82% to 65% was prioritized after the efficacy parameters. Conclusions: Patients with aRCC highly value less burdensome treatment regimens and improved QoL in addition to improvement in survival. This highlights the need for a broader context beyond efficacy and safety when discussing treatment options with patients. Funding: This study was supported by Bristol Myers Squibb.

Adherence to standard of care (SOC) therapy for the treatment of metastatic hormone-sensitive prostate cancer (mHSPC): A single-institution analysis

103

Background: Androgen deprivation therapy (ADT) has been the backbone of treatment for mHSPC for decades. In recent years, multiple randomized controlled trials demonstrating an overall survival (OS) benefit of combination treatment (e.g. ADT + novel hormonal agent and/or chemotherapy) has made this the current SOC. Large real-world reports have shown a significant number of patients are still being treated below the SOC with ADT alone, but these databases do not include patient level data to help understand the rationale for treatment decisions. We reviewed our institution’s treatment patterns for mHSPC to better understand why some patients are being treated with ADT alone. Methods: We conducted a retrospective analysis on patients who initiated treatment for mHSPC from 2017-2021 at Cleveland Clinic. Patient characteristics were recorded, including age and histology. Treatment characteristics, including location of treatment, treatment regimen, and treatment rationale (if not treated with SOC) were noted. Results: Four hundred forty-nine patients were included, with diagnosis of metastatic disease made at a median of 63 years, of which 446 started treatment with systemic therapy. The vast majority of patients were managed by a medical oncologist (95.5%). About half of the patients (49.8%) received treatment at the main campus, with the remaining patients being treated at an affiliated regional hospital (28.7%) or outpatient medical center (21.5%). Additional characteristics are shown. Out of the 446, 40 (9.0%) patients received ADT alone. Reasons for ADT monotherapy included patient preference (n = 13), cost (n = 2), and poor functional status/comorbidities (n = 4). Twenty (50%) of the patients who got ADT alone had no documented rationale for why this treatment plan was elected. One patient was lost to follow-up. For patients who received only ADT, 12 were treated at main campus, 20 were treated at a regional hospital, and 8 were treated at an outpatient medical center. Conclusions: At our institution, adherence to treatment up to SOC for mHSPC was better than previous real-world reports. There were documented reasons for not treating mHSPC up to SOC combination therapy for half of the patients who got ADT monotherapy. It remains unclear why the remaining half did not get combination therapy up to the SOC. [Table: see text]

Phase II study of axitinib prior to partial nephrectomy to preserve renal function: An interim analysis of the PADRES clinical trial

683

Background: In renal cell carcinoma (RCC), partial nephrectomy (PN) is indicated for patients with solitary kidney, chronic kidney disease, or bilateral tumors. A subset of these patients, however, may have large and complex renal masses not initially suitable for PN. Neoadjuvant Tyrosine Kinase Inhibitor therapy has shown promising results in cytoreducing renal tumors and may permit PN in circumstances not otherwise feasible. Methods: This was a single arm phase II clinical trial of neoadjuvant axitinib in patients with complex (RENAL nephrometry score 10-12 and cT1b-cT3M0) biopsy-proven clear cell RCC with strong indications for partial nephrectomy (PN), and in whom radical nephrectomy may result in dialysis dependence. Axitinib 5 mg was administered orally twice daily for 8 weeks prior to surgery. Primary outcome was reduction in longest tumor diameter; secondary outcomes included tumor response (RECIST), change in RENAL score, feasibility of PN, change in estimated glomerular filtration rate (DeGFR), and post-surgical complications. Results: 26 patients were enrolled. 19 (73.1%) patients had ≥ clinical T3a staged tumors. Post therapy, 17 (65.4%) patients had ≥T3a staged tumors. Axitinib resulted in reductions in tumor size (7.7 vs. 6.3 cm, p<0.001) and RENAL score (11 vs. 10, p <0.001); 9 (34.6%) had partial response, and 17 (65.4%) stable disease by RECIST criteria. PN was successfully performed in 19 (73.1%); 24 (96.8%) achieved negative margins. Six (23.1%) had Clavien III-IV post-surgical complications. Median percentage DeGFR was 14.7%; one (3.8%) patient who had a radical nephrectomy had long-term dialysis dependence. Conclusions: Neoadjuvant axitnib resulted in significant reductions in tumor size and complexity, enabling PN in a cohort of complex renal masses, and with acceptable safety and functional preservation. Clinical trial information: NCT03438708 . [Table: see text]

Phase II trial of intermittent therapy in patients (pts) with metastatic renal cell carcinoma (mRCC) treated with front-line ipilimumab and nivolumab (Ipi/Nivo)

672

Background: The combination of ipilimumab and nivolumab (Ipi/Nivo) is approved for patients (pts) with treatment-naïve, intermediate- and poor-risk metastatic renal cell carcinoma (mRCC), but duration of therapy and safety/efficacy of re-induction at progression is unknown. A phase II trial of intermittent Ipi/Nivo with re-induction at progression was conducted (NCT03126331). Methods: Patients with treatment-naïve mRCC were treated with induction Ipi/Nivo followed by up to 24 weeks (+/- 8 weeks) of maintenance Nivo. Pts who achieved a complete response (CR) or partial response (PR) were eligible for inclusion and entered a treatment-free observation period. Pts were restaged every 12 weeks. Pts with no disease progression (PD) remained off therapy. Upon PD, pts were re-challenged with 2 doses of Ipi/Nivo every 3 weeks, with 1 or 2 more doses at physician discretion. The study objectives were to estimate success rate of observation in pts who achieve a CR/PR (defined by 50% of CR/PR pts sustaining a treatment-free interval of at least 9 months), and to assess toxicity in pts undergoing re-induction. The study was closed early given poor accrual in the rapidly changing mRCC treatment landscape. Results: Nine pts were included; 89% male, median age 57, 78% prior nephrectomy, 67% clear-cell histology, all had KPS ≥ 80%, and 78% were intermediate-risk by IMDC criteria. All pts had 4 doses of induction Ipi/Nivo. Response to Ipi/Nivo and Nivo maintenance prior to enrollment was 33% CR and 67% PR. Most (78%) pts patients have remained off therapy, with a median treatment-free interval (TFI) of 34.3 months (range, 8.7-41.8). The success rate of 0.78 (95% CI: 0.40-0.97) exceeded the pre-specified threshold of 50%. Two pts had PD off therapy (3 and 8 months after therapy cessation; both with best initial response of PR). Both received 2 cycles of re-induction Ipi/Nivo. No grade 3 or greater toxicities occurred with re-induction, but both pts developed PD at their first scans after re-induction. Conclusions: This pilot prospective study demonstrates that patients with a radiographic response to Ipi/Nivo can have prolonged treatment-free intervals. Further studies of de-escalation strategies are warranted. Correlative investigations for this trial are ongoing. Clinical trial information: NCT03126331 .

Treatment-free survival (TFS) outcomes from the phase II study of nivolumab and salvage nivolumab + ipilimumab in advanced clear cell renal cell carcinoma (aRCC) (HCRN GU16-260-Cohort A)

604

Background: Treatment with immunotherapy can be associated with prolonged disease control after discontinuation without the need for further anticancer therapy. Toxicity from therapy can also persist after cessation. TFS with and without toxicity can characterize survival time. Significant TFS was reported for CheckMate 067 trial in pts with metastatic melanoma (Regan et al JITC 2021) and CheckMate 214 trial for pts with aRCC (Regan et al CCR 2021), but treatment was often halted for toxicity rather than a pre-defined treatment endpoint. We therefore sought to assess TFS in the HCRN GU16 260 trial, which was designed to reduce toxicity and to cap immunotherapy duration (Atkins et al JCO 2022). Methods: Data were analyzed from 128 patients (pts) with clear-cell aRCC treated with first-line nivolumab (NIVO) monotherapy for up to 2 years. As part of the protocol, salvage nivolumab/ipilimumab (NIVO/IPI) for up to 1 year was provided to eligible patients with disease progression at any point or stable disease at 48 weeks (28% of pts). TFS was defined as the area between Kaplan-Meier curves for time from registration to protocol therapy cessation and for time from registration to subsequent therapy initiation or death, estimated from 36-month (mo) mean times. The time on treatment or off treatment with grade 3+ treatment-related adverse events (TRAEs) was also captured. Results: At 36 mos from enrollment, 68.3% of pts were alive: 96.8% of IMDC favorable-risk (FAV) pts and 56.6% of those with intermediate/poor-risk (I/P), respectively. The 36-mo mean time on protocol therapy was 11.5 mos (16.0 mos for FAV pts and 9.6 mos for I/P pts). The 36-mo mean TFS for the whole population was 9.4 mos. For FAV pts the mean TFS was 12.9 mos, of which TFS with grade 3+ TRAEs was 1.5 mos. For I/P pts, the mean TFS was 8.0 mos, of which TFS with grade 3+ TRAEs was 1.0 mos. At 36 mos, 65.6% of FAV pts and 27.1% of I/P pts were alive and second-line treatment-free. Conclusions: NIVO monotherapy with salvage NIVO/IPI in non-responders is an active treatment approach in treatment-naïve pts with aRCC and results in substantial TFS and toxicity-free TFS. TFS was particularly noted in pts with FAV disease, further supporting the use of an immunotherapy-only regimen in this population. Clinical trial information: NCT03117309 . [Table: see text]

Optimal treatment by invoking biologic clusters in renal cell carcinoma (OPTIC RCC)

TPS742

Background: The first-line treatment for metastatic clear cell renal cell carcinoma (mccRCC) includes an immuno-oncology (IO) based combination. The current standard regimens include a PD-1 inhibitor plus either (1) an anti-CTLA-4 inhibitor (IO/IO), or (2) an anti-vascular endothelial growth factor receptor (VEGFR) tyrosine kinase inhibitor (TKI) (IO/TKI). Currently, there is no level 1 evidence to guide physician’s choice between an IO/IO versus IO/TKI combination. The phase III IMmotion 151 trial performed RNA-seq from 823 ccRCC tumors and established seven biologically distinct gene expression clusters of ccRCC (Motzer and Rini et al., Cancer Cell 2020). The seven clusters showed differential responses to immune checkpoint inhibitor and may serve as a predictive biomarker to select frontline treatment. Methods: This trial is a phase II, multicenter study using the established biologic clusters to assign patients with mccRCC to either an IO/IO (ipilimumab/nivolumab) or an IO/TKI (nivolumab/cabozantinib) regimen. Patients diagnosed with mccRCC without prior systemic therapy (including in the neoadjuvant or adjuvant setting) and at least one measurable lesion as defined by RECIST 1.1 are eligible for enrollment. RNA-seq will be performed on metastatic tumor specimens and used to assign tumor clusters. Patients with cluster 1/2 tumors will be assigned to the nivolumab/cabozantinib arm; patients with cluster 4/5 tumors will be assigned to the ipilimumab/nivolumab arm. Cluster 3/6/7 will be excluded. The primary endpoint is overall response rate (ORR) per RECIST 1.1. The hypothesis is that use of tumor clusters to assign front-line therapy to either nivolumab/cabozantinib or ipilimumab/nivolumab will lead to a 20% greater ORR compared to unselected historical controls in CheckMate 9ER (ORR: 55%) or CheckMate 214 (ORR: 40%). This trial adopts Simon’s MiniMax two-stage design (power: 80%, one-sided α: 0.1). For the nivolumab/cabozantinib arm, stage I will enroll 12 eligible patients. If there are 7 or more responders in the first 12 patients, the trial will continue for stage II to enroll additional 14 patients (total n=26). The primary endpoint will be met if there are 18 or more responders (ORR ≥75%). For the ipilimumab/nivolumab arm, stage I will enroll 16 eligible patients. If there are 7 or more responders in the first 16 patients, the trial will continue for stage II to enroll additional 12 patients (total n=28). The primary endpoint will be met if there are 15 or more responders (ORR ≥60%). Key secondary endpoints include progression-free survival (PFS), depth of response>80%, and rate of immune-related adverse events (irAEs). This trial is funded by the Department of Defense Kidney Cancer Research Program Clinical Trial Award (W81XWH-22-1-1033) (NCT05361720). Clinical trial information: NCT05361720 .

A phase 1b/2 study of batiraxcept (AVB-S6-500) in combination with cabozantinib in patients with advanced or metastatic clear cell renal cell carcinoma (ccRCC)

666

Background: Activation of the GAS6/AXL pathway promotes tumor cell proliferation; high levels of GAS6 and AXL have been associated with drug resistance and decreased survival. Batiraxcept is an ultra-high affinity decoy protein that captures GAS6, preventing it from activating AXL signaling. Serum soluble AXL (sAXL)/GAS6 ratio correlates with response to batiraxcept in advanced ovarian cancer. Batiraxcept in combination with cabozantinib is being evaluated in patients (pts) with metastatic clear cell renal cell carcinoma (ccRCC) in this study. Prior studies of cabozantinib in similar pt populations have shown an overall response rate (ORR) ranging from 15 – 32.5% and progression-free survival (PFS) from 3.7-7.2 months (mo). Methods: Key eligibility criteria include previously treated ccRCC pts, excluding prior cabozantinib. Objectives were to determine the safety of batiraxcept plus cabozantinib 60 mg, the recommended phase 2 dose (RP2D), ORR, PFS, duration of response. Correlative endpoints included assessment of baseline serum sAXL/GAS6 with ORR and PFS. Results: In Phase 1b (P1b), 26 pts received at least one dose of batiraxcept with cabozantinib (16 pts - 15 mg/kg; 10 pts - 20 mg/kg). Median age was 60 (range 40-81), male 85% (n=22), IMDC intermediate/poor risk 77% (n=20). All pts received prior immuno-oncology (IO) therapy, 54% (n=14) also received VEGF-TKI; 85% (n=22) received 1 to 2 prior lines of therapy (range 1-6). Median follow-up time was 11.6 mo (range 3.7-18). The RP2D is 15 mg/kg. Related adverse events (AE) any grade and grade ≥ 3 were 100% and 39% (n=10), respectively. Cabozantinib dose reductions occurred in 54% (n=14). AEs of special interest were grade 1 or 2 infusion related reactions, 27% (n=7). Batiraxcept was discontinued due to disease progression 62% (n=16) or toxicity 12% (n=3). The table shows P1b efficacy, ORR of 42%, median PFS of 9.3 mo, and DCR of 84%. Twenty (77%) pts had high baseline sAXL/GAS6 levels; ORR was 55% (11/20) with mPFS of 9.3 mo, compared to 0% ORR and mPFS 6.4 mo in the low sAXL/GAS6 pts. Conclusions: Batiraxcept was well tolerated when combined with cabozantinib. No new safety signals were noted. Efficacy for the combination is encouraging compared to historical cabozantinib monotherapy data. Higher GAS6 levels were predictive for treatment response. The P2 accrual is complete and efficacy data are maturing. A P3 trial plans to evaluate the efficacy in ccRCC patients who have progressed on IO-based and VEGF-TKI therapies. Clinical trial information: NCT04300140 . [Table: see text]

Assessment of surgical complications in patients with metastatic clear cell renal cell carcinoma (mccRCC) receiving perioperative cabozantinib and nivolumab on Cyto-KIK clinical trial

691

Background: The perioperative safety of cabozantinib and nivolumab in mccRCC, and the optimal timing to hold cabozantinib prior to surgery, are unknown. Methods: In this phase 2 trial, patients with mccRCC are given cabozantinib (40mg daily) and nivolumab (480mg q4 weeks) for 12 weeks prior to cytoreductive nephrectomy. Post-operatively, patients resume treatment with cabozantinib and nivolumab until disease progression. A 3+3 design was used to evaluate the safety of the interval (21 or 14 days) between the discontinuation of cabozantinib and nephrectomy. Evaluable patients completed at least 10 of 14 cabozantinib doses prior to the pre-specified period of stopping pre-operative cabozantinib. Surgical complications assessed using the Clavien-Dindo classification system is a secondary endpoint of this study. Results: 16 patients have been enrolled and 14 completed nephrectomy to date. 12 (75%) of patients are male, 4 (25%) female, ages 44-77 years old with median age at diagnosis 58.5 years old. BMIs ranged from 17.8 kg/m2 to 39.3 kg/m2 with median BMI of 28.7kg/m2. 63% of patients were classified by IMDC as intermediate-risk and 37% as poor-risk disease. Dose reductions of cabozantinib occurred in 14% of patients who completed nephrectomy and cabozantinib held in 42% of nephrectomy patients during the course of treatment. Three evaluable patients completed nephrectomy within the 21-day interval and 5 within the 14-day interval after discontinuation of cabozantinib. There were no treatment-related surgical complications in patients who completed nephrectomy and there were no delays in resuming combination systemic therapy after surgery. Conclusions: Combination cabozantinib and nivolumab can be safely administered up to 14 days prior to cytoreductive nephrectomy. Clinical Trial Information: NCT04322955 Clinical trial information: NCT04322955 .

Transcriptomic Features of Cribriform and Intraductal Carcinoma of the Prostate

BACKGROUND

Cribriform (CF) and/or intraductal carcinoma (IDC) are associated with more aggressive prostate cancer (CaP) and worse outcomes.

OBJECTIVE

The transcriptomic features that typify CF/IDC are not well described and the capacity for clinically utilized genomic classifiers to improve risk modeling for CF/IDC remains undefined.

DESIGN, SETTING, AND PARTICIPANTS

We performed a retrospective review of CaP patients who had Decipher testing at a single high-volume institution. Index lesions from radical prostatectomy specimens were identified by genitourinary pathologists who simultaneously reviewed prostatectomy specimens for the presence of CF and IDC features. Patients were grouped based on pathologic features, specifically the absence of CF/IDC (CF-/IDC-), CF positive only (CF+/IDC-), and CF/IDC positive (CF+/IDC+).

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Clinical, pathologic, and genomic categorical variables were assessed using the Pearson chi-square test, while quantitative variables were assessed with the Kruskal-Wallis test. Multivariable logistic regression was used to identify the predictors of high-risk Decipher scores (>0.60). A gene set enrichment analysis was performed to identify genes and gene networks associated with CF/IDC status.

RESULTS AND LIMITATIONS

A total of 463 patients were included. Patients who were CF+/IDC+ had the highest Decipher risk scores (CF+/IDC+: 0.79 vs CF+/IDC-: 0.71 vs CF-/IDC-: 0.56, p < 0.001). On multivariate logistic regression, predictors of high-risk Decipher scores included the presence of CF, both alone (CF+/IDC-; odds ratio [OR]: 5.45, p < 0.001) or in combination with positive IDC status (CF+/IDC+; OR: 6.87, p < 0.001). On the gene set enrichment analysis, MYC pathway upregulation was significantly enriched in tumor samples from CF/IDC-positive patients (normalized enrichment score [NES]: 1.65, p = 0.046). Other enriched pathways included E2F targets (NES: 1.69, p = 0.031) and oxidative phosphorylation (NES: 1.68, =0 .033).

CONCLUSIONS

This is the largest series identifying an association between a clinically validated genomic classifier and the presence of CF and IDC at radical prostatectomy. Tumors with CF and intraductal features were associated with aggressive transcriptomic signatures.

PATIENT SUMMARY

Genomic-based tests are becoming readily available for the management of prostate cancer. We observed that Decipher, a commonly used genomic test in prostate cancer, correlates with unfavorable features in tissue specimens.

A phase 1b/2 study of batiraxcept (AVB-S6-500) in combination with cabozantinib, cabozantinib and nivolumab, and as monotherapy in patients with advanced or metastatic clear cell renal cell carcinoma (NCT04300140)

TPS4599

Background: In clear cell renal cell carcinoma (ccRCC) the constitutive expression of hypoxia induced factor 1-α leads to increased expression of AXL. AXL overexpression has been associated with the development of resistance to VEGF inhibitors and suppression of the innate immune response through inhibition of macrophage-driven inflammation. Batiraxcept is a recombinant fusion protein dimer containing an extracellular region of human AXL combined with the human immunoglobulin G1 heavy chain (Fc), which demonstrates highly potent, specific AXL inhibition. In preclinical studies using the 786-O, M62, and SN12L1 tumors, batiraxcept monotherapy resulted in a significant reduction of tumor growth compared to control. In healthy volunteer and ovarian cancer clinical studies, batiraxcept was well tolerated with no dose-related adverse events, and a maximum tolerated dose was not reached. Therefore, batiraxcept could be tested as either a monotherapy or in combination with standard of care drugs in patients with metastatic ccRCC. The Phase 1b dose-escalation portion of this study evaluated batiraxcept in combination with standard of care cabozantanib in patients who progressed on or after first line therapy. No DLT was observed at either of two batiraxcept doses evaluated. The recommended Phase 2 dose of batiraxcept has been identified as 15 mg/kg every 2 weeks (q2w) with cabozantinib 60 mg based upon safety, PK/PD, and preliminary efficacy data. Methods: This Phase 2, multi-center, open-label study includes three parts: Part A) batiraxcept 15 mg/kg q2w in combination with cabozantinib 60 mg daily for ccRCC subjects who have progressed on or after one line of therapy, n=25. Part B) batiraxcept 15 mg/kg q2w with cabozantinib 40 mg daily and nivolumab at the investigator’s choice (240 mg q2w or 480 mg q4w) for first line treatment of advanced or metastatic ccRCC subjects, n=20. If no safety signals are observed in the first 6 subjects enrolled, 10 subjects will be enrolled in the first stage of a Simon 2-stage minmax statistical design. If ≥ 6/10 subjects achieve PR or CR, stage 2 will open to enroll up to 20 total subjects. Part C) batiraxcept 15 mg/kg q2w monotherapy for subjects with advanced/metastatic ccRCC ineligible for curative intent therapies, n=10. The primary objective for each arm is objective response rate by RECIST v1.1. Secondary objectives include safety, duration of response, clinical benefit rate, progression free survival by RECIST v1.1, and overall survival. Exploratory objectives include pharmacokinetic and pharmacodynamic assessments. The Phase 2 portion of this Ph1b/2 study is currently enrolling. Clinical trial information: NCT04300140.

First-in-human study of SRF388, a first-in-class IL-27 targeting antibody, as monotherapy and in combination with pembrolizumab in patients with advanced solid tumors

2501

Background: The immunoregulatory cytokine IL-27 upregulates inhibitory immune checkpoint receptors (eg, PD-L1, TIGIT) and downregulates proinflammatory cytokines (eg, IFNγ, TNFα). SRF388 is a fully human IgG1 blocking antibody to IL-27 with potential to promote immune activation in the tumor microenvironment. A phase 1 study was conducted to establish the preliminary safety of SRF388 and to identify recommended phase 2 doses (RP2D) suitable for monotherapy and combination expansions (NCT04374877). Methods: The dose-escalation study (accelerated single patient followed by standard 3+3) enrolled patients (pts) with advanced treatment-refractory solid tumors. Upon RP2D selection, monotherapy and combination expansions opened for treatment-refractory clear cell renal cell cancer (ccRCC), hepatocellular cancer (HCC), and non-small cell lung cancer. SRF388 was administered IV every 4 weeks (wks) as monotherapy and every 3 wks with pembrolizumab. Tumor response was assessed by RECIST1.1. Results: The monotherapy dose-escalation enrolled 29 pts with doses ranging from 0.003 to 20 mg/kg. Median age was 64 years. Most pts were female (62%) with ECOG PS of 1 (72%). Approximately 80% had prior PD-(L)1 blockade, and 48% had ≥4 prior therapies. Treatment-related adverse events (TRAEs) occurred in 21%, and all were low grade. Fatigue was the only TRAE reported in ≥10% (n = 3). No dose-limiting toxicities (DLTs) or Grade ≥3 TRAEs were observed. Median time on study was 9 wks (range 0–59). One patient with highly treatment-refractory NSCLC experienced a confirmed partial response (PR) at 8 wks that was durable for 20 wks. Nine pts (31%) experienced disease stabilization at 8 wks, with 6 of 9 exhibiting durable disease control at 6 months. Of the 7 pts with ccRCC in the dose-escalation portion of the trial, 3 (43%) experienced durable disease control for ≥20 wks (range: 20-32). With doses up to 20 mg/kg, SRF388 PK remain linear with an estimated T1/2 of 10-12 days. PK characteristics and safety profile support dosing every 3 or 4 wks. Based on safety, tolerability, PK, peripheral pSTAT1 inhibition, and preliminary efficacy, 10 mg/kg was selected as the RP2D. Both the pembrolizumab safety cohort (n = 10) and Stage 1 of the ccRCC monotherapy expansion (n = 17) have fully enrolled. Of the 10 evaluable pts with ccRCC, 1 confirmed monotherapy PR has been reported, enabling Stage 2 initiation. Changes in several serum cytokines and chemokines were observed after SRF388 administration, including expected increase in circulating IL-27 levels. Conclusions: Results of IL-27 pathway blockade with a first-in-class therapeutic demonstrates that SRF388 has good tolerability with encouraging preliminary antitumor activity as a monotherapy. Updated data, including safety and clinical outcomes as well as correlative biomarker analyses, will be presented. Clinical trial information: NCT04374877.

Prognostic factors and clinical outcomes in patients with upper tract urothelial carcinoma undergoing surgery: The Cleveland Clinic experience

4593

Background: Upper tract urothelial carcinoma (UTUC) is a rare and heterogeneous disease accounting for approximately 5-10% of UC. While tumor grade and stage are known prognostic factors, data on other factors affecting outcomes in UTUC patients (pts) undergoing surgery is scant. We studied effect of various clinical factors and treatment on outcomes in UTUC. Methods: This is a single-institution retrospective study of 607 pts with UTUC undergoing surgery (nephroureterectomy (NU) or ureterectomy (U)) between Jan 2000 and Dec 2020. We studied effect of demographics, clinicopathological features, tumor location, preoperative Neutrophil-to-Lymphocyte ratio (NLR) and Albumin-to-Globulin ratio (AGR) and use of neoadjuvant or adjuvant chemotherapy on overall survival (OS) and recurrence free survival (RFS). Results: Of the 607 pts 401 (66.06%) were males and 355 (58.48%) were > 70 yrs; 232 pts (38.22%) had UTUC of renal pelvis, 242 (39.87%) of ureter and 133 (21.91%) of both. 542 pts (89.29%) underwent radical NU and 65 (10.71%) segmental U; 328 patients (54.04%) were diagnosed with muscle invasive UC (MIUC) ( > / = pT2) and 276 (45.47%) with non-MIUC ( < / = pT2). Only 51 (8.4%) pts had lymph node positive (N+) disease. Lymphovascular invasion (LVI) was identified in 163 (26.85%) and carcinoma- in-situ (CIS) in 163 (26.85%) pts. Surgical margins were positive in 92 pts (15.16%). Median NLR cutoff was 3.25 and AGR cutoff was 1.25 (dichotomized based on literature). 44 pts (7.2%) received Neoadjuvant chemotherapy and 49 pts (8%) received adjuvant chemotherapy. Tumor recurrence occurred in 216 pts (35.58%) of which 65% were at urothelial and 35% at non-urothelial sites. With median follow up of 35.2 mos, median OS was 82.69 mos and 5-yr OS rate was 60%; median RFS was 29.47 mos and 5-yr RFS rate was 40%. High grade, age > / = 70 yrs, high NLR, low AGR, presence of LVI, positive margins, CIS, MIUC, N+ disease were associated with worse outcomes. Pts with only renal pelvis involvement had better OS. Conclusions: In this large, long term follow-up series of UTUC pts, we identified several prognostic factors besides grade and stage that impact outcomes. These findings warrant further validation for use in clinical practice. [Table: see text]

Phase II randomized double blind trial of axitinib (Axi) +/- PF-04518600, an OX40 antibody (PFOX) after PD1/PDL1 antibody (IO) therapy (Tx) in metastatic renal cell carcinoma (mRCC)

4529

Background: Immune checkpoint blockade has revolutionized mRCC Tx, but primary and acquired resistance continues to result in poor patient outcomes. OX40 (CD-134) mediates IO resistance. Co-stimulatory OX40 (CD-134) activates exhausted T-cells. OX40 activation in dendritic cells increases the proliferation, effector function, and survival of T cells. PFOX is an agonist for OX40. We hypothesized that PFOX + the VEGFR inhibitor Axi would improve outcomes vs. Axi in patients (pts) with mRCC after IO Tx. Methods: Pts with predominantly clear cell mRCC were stratified for MSKCC risk groups then randomized 1:1 to Axi 5mg po bid plus PFOX 0.3mg/kg iv (Arm 1) or placebo (PL) iv (Arm 2) on Day 1 of a 2-week cycle. The primary endpoint was progression free survival (PFS); secondary endpoints included overall survival (OS), objective response rate (ORR), duration of response (DOR) per RECIST v1.1, and safety/tolerability. A prespecified interim analysis (IA) tested PFS at a 1-sided P < 0.02 when ≥ 33 events were observed. Results: Between February 2018 and October 2021 a total of 59 pts were randomly assigned and treated with Axi+PFOX (N = 29) or Axi+PL (N = 30). Pt and disease characteristics are summarized in the table. As of October 2021, 38 PFS events had occurred, 19 on each arm. The IA rejected the hypothesis of added efficacy for PFOX with a p of 0.0089. Subsequently the study was closed to new accrual. At a median follow up of 13.4 mo, median PFS was 13.1 (6-15.8) months (mo) for Arm 1 and 8.5 (5.5-11) mo for Arm 2 (HR = 0.85 [95% CI: 0.45-1.60] p = 0.61). After adjusting by MSKCC risk group and prior lines of Tx, HR = 0.74 [95% CI: 0.38-1.46] p = 0.39. Median OS was not reached (adjusted HR = 0.71 [95% CI: 0.24-2.12] p = 0.54). ORR Arm 1: 31% PR, 52% SD, 14% PD, and Arm 2: 37% PR, 50% SD, 13% PD. Median DOR 9.1 (3.3-23.9) mo for Arm 1, and 7.5 (1.8-32.7) mo. for Arm 2. Rates of any grade Tx related adverse events (TRAEs; 93% vs 100%), including grade 3 or 4 TRAEs (66% vs 47%), in Arm 1 and Arm 2, respectively. 4 pts discontinued Tx due to TRAE, 3 in Arm 1 (1 grade 3 hypertension, 1 grade 2 stroke, 1 grade 3 bullous dermatitis) and 1 in Arm 2 (grade 4 ALT elevation). The most common TRAEs were diarrhea 52%, hypertension 52%, fatigue 41%, nausea 41% for Arm 1 and hypertension 67%, diarrhea 53%, fatigue 50% for Arm 2. Conclusions: In IO-pretreated mRCC pts, Axi + PFOX did not improve outcomes compared to Axi alone. Clinical trial information: NCT03092856. [Table: see text]

A phase 1b/2 study of batiraxcept (AVB-S6-500) in combination with cabozantinib in patients with advanced or metastatic clear cell renal cell (ccRCC) carcinoma who have received front-line treatment (NCT04300140)

4511

Background: AXL is up-regulated by hypoxia-inducible factor-1 signaling in both VHL-deficient and hypoxic tumor cells and plays a critical role in the metastatic phenotype of ccRCC. Batiraxcept is a recombinant fusion protein containing an extracellular region of human AXL combined with the human immunoglobulin G1 heavy chain (Fc), demonstrating highly potent, specific AXL inhibition. Methods: Batiraxcept at doses of 15 and 20 mg/kg, plus cabozantinib 60 mg daily, was evaluated using a 3+3 dose escalation study design. The primary objective was safety; secondary and exploratory objectives included identification of the recommended phase 2 dose (RP2D), overall response rate (ORR), and duration of response (DOR). Correlation of serum soluble AXL (sAXL)/GAS6 with ORR was evaluated. Key eligibility criteria include previously treated (2L+) ccRCC patients; prior treatment with cabozantanib was not allowed. sAXL/GAS6 was evaluated at baseline. Results: Data as of 4-February-2022, Phase 1b enrolled 26 patients, 16 patients treated with 15 mg/kg and 10 patients with 20 mg/kg dose of batiraxcept. Baseline characteristics: median age 60 (40-81); male 22 (85%); median prior line of therapy 1 (1-5); IMDC risk group of favorable 6 (23%); prior VEGF inhibitor 15 (58%); 100% with prior immunotherapy. At median follow up of 4.9 months, 92% (n=24) patients remained on the study. No dose limiting toxicities were observed at either 15 mg/kg or 20 mg/kg dose. Batiraxcept and cabozantinib related adverse events (AEs) occurred in 17 subjects (65%). Most common related AE include decreased appetite 31% (n=8), diarrhea and fatigue 23% (n=6). Grade 3 related AEs occurred in 4 patients (15%) including diarrhea, thromboembolism, hypertension, small bowel obstruction, and thrombocytopenia (n=1, 4% each) being most common. No grade 4 or 5 related AEs were observed. The ORR was 46% (n=12, partial response [PR]; Table). No patients had primary progressive disease. Among the patients who had baseline sAXL/GAS6 ratio of ≥ 2.3, the ORR was 67% (12/18). Regardless of baseline sAXL/GAS6 ratio, 3-month DOR was 100%; and 6-month progression free survival was 79%. Batiraxcept PK levels were similar across both doses and GAS6 levels suppressed through the dosing period. Conclusions: Batiraxcept plus cabozantinib is well tolerated. The RP2D of batiraxcept was identified as 15 mg/kg. Early efficacy signals were observed including 100% DOR at 3 months. Baseline sAXL/GAS6 may serve as a potential biomarker to enrich the population. Clinical trial information: NCT04300140. [Table: see text]

A genomic classifier for prostate cancer correlates with adverse pathologic features: Transcriptomic features of cribriform and intraductal carcinoma of the prostate

268

Background: Invasive cribriform and intraductal carcinoma (CF/IDC) portends an unfavorable prognosis for patients diagnosed with prostate cancer (CaP). Limited studies with small sample sizes have explored whether genomic classifiers are associated with IDC and/or CF status. We investigated the correlation between Decipher genomic risk score and IDC/CF status and assessed PCa transcriptomic features. Methods: We performed a retrospective review of CaP patients who had Decipher testing at a single high volume center between 2009-2020. The highest grade index lesion from radical prostatectomy specimens was identified by GU pathologists and used for Decipher testing. Genitourinary pathologists reviewed prostatectomy specimens for the presence of CF and IDC features. Patients were divided into three groups based on pathologic features, absent CF/IDC (CF-/IDC-), CF positive only (CF+/IDC-), and CF/IDC positive (CF+/IDC+). Categorical clinical, genomic, and pathologic variables were assessed using the Pearson Chi-Square test, quantitative with the Kruskal-Wallis test. Multivariable logistic regression was used to identify predictors of high-risk Decipher GC scores. The Kaplan-Meier method with log-rank was used to compare biochemical recurrence free survival. Differential gene expression and gene network analysis was used to identify genes and pathways associated with IDC/CF features. Results: 463 patients were included with a median follow-up of 25 months. Patients who were CF+/IDC+ had higher GC scores (CF+/IDC+: 0.77 vs. CF+/IDC-: 0.71 vs. CF-/IDC-: 0.61, p<0.001). Patients who were CF+/IDC+ had a higher percentage of Gleason grade group >3 (CF+/IDC+: 79% vs. CF+/IDC-: 52% vs. CF-/IDC-: 52%, p<0.001). On multivariate logistic regression, predictors of high-risk GC score were presence of CF+/IDC+ features on final pathology (OR: 3.94, p<0.001) and pathologic Gleason grade group >3 (OR: 1.58, p=0.04). Transcriptomic analysis revealed that the hallmark androgen response pathway was significantly upregulated in CF+/IDC+ patients (Log fold change: 15.7, p<0001). Conclusions: This is the largest series investigating the association of a clinically validated genomic classifier and pathologic features such as cribriform and intraductal carcinoma. These findings have implications for the use of genomic classifiers in settings where expert GU pathology is not readily available and in potentially unmasking adverse histology at the time of biopsy.[Table: see text]

Immunological correlates of response and immune-mediated toxicity in checkpoint inhibitor (ICI)-treated metastatic urothelial carcinoma (mUC) patients (pts)

526

Background: Myeloid derived suppressors cells (MDSC) are immune cells that create an immunosuppressive microenvironment. Increased expression of MDSC subsets is associated with worse overall survival in ICI-treated mUC pts, but their role in immune-related adverse events (irAE) is unknown. Immune profiles associated with irAE are also unknown. We investigated associations of MDSC and –omics profiles with response and irAE in ICI-treated mUC pts. Methods: Baseline (B) and on-treatment (Tx) blood samples were collected from ICI-treated mUC pts. MDSC were measured in fresh unfractionated whole blood (WB) and in peripheral blood mononuclear cells (PBMC). MDSC were identified by flow cytometry in WB, defined as LinloCD33+/HLADR-, and subclassified as polymorphonuclear (PMN)-MDSC (CD15+/CD14-), monocytic (M)-MDSC (CD15-/CD14+), and uncommitted (UC)-MDSC (CD15-/CD14-). MDSC populations were presented as % of live nucleated blood cells and as absolute numbers from WB. irAE severity was graded by CTCAE v5. In a subcohort of 17 pts, proteomics and transcriptomics were analyzed via Olink and Bulk RNAseq, respectively. Wilcoxon rank sum test compared MDSC and –omics among response and irAE groups. Kruskal-Wallis test compared –omics results between irAE responders (irAE-R), irAE non-responders (irAE-NR), and no irAE/non-responders (noAE-NR). Results: 41 ICI-treated mUC pts (25 anti-PD-L1, 16 anti-PD-1) had at least 1 MDSC sample: 28 pts at B, 30 pts at Tx, and 17 pts at both B and Tx. Primary UC sites were bladder (78%) and upper tract (22%); 73% male; median age 72 (range, 28-82); 85% had KPS > 80%; 51% had visceral metastasis. ICI was first and second-line therapy in 37% and 63% of pts, respectively. 13 pts were responders (R); 26 pts were non-responders (NR); 2 pts were not evaluable. 22 pts developed irAE. Median time to irAE was 84 days (range, 21-145); 10 pts required steroids; 3 required ICI discontinuation. UC-MDSC was predominant in WB and PMN-MDSC in PBMC in both B and Tx. Between B and Tx, WB UC-MDSC and PB UC-MDSC increased in R (n = 13; p = 0.04), but decreased in NR (n = 26; p = 0.02). In the subcohort of 17 pts, 11 had irAE (7 irAE-R; 4 irAE-NR), 6 had noAE-NR. Proteomic analysis showed increased expression of CXCL12 in noAE-NR pts (p = 0.006) and increased expression of IL-8 (p = 0.016), IL-18 (p = 0.012), and IL-18R1 (p = 0.016) in all irAE pts. At the transcriptome level, upregulation of IFN-γ was associated with response, whereas upregulation of both IFN-γ and IFN-α differentiated irAE-R from irAE-NR. Conclusions: In ICI-treated mUC pts, WB & PB UC-MDSC increased in R and decreased in NR between B and Tx. Increased expression of pro-inflammatory chemokines was observed in irAE pts, independent of response. A distinct inflammatory pathway was observed in irAE-R. Prospective investigation of blood-based biomarkers of response and irAE development is warranted.

Phase II study of nivolumab and salvage nivolumab + ipilimumab in treatment-naïve patients (pts) with advanced clear cell renal cell (HCRN GU16-260-Cohort A): Final report

288

Background: Nivolumab (nivo) is FDA approved for patients (pts) with VEGFR TKI-resistant RCC and the nivo + ipilimumab (nivo/ipi) combination is FDA approved for treatment naïve pts with IMDC intermediate and poor risk renal cell carcinoma (RCC). Little information was available on the efficacy and toxicity of nivo monotherapy in treatment naïve RCC or the efficacy of nivo/ipi salvage in pts with tumors resistant to initial nivo monotherapy. Methods: Eligible pts with treatment naïve RCC received nivo 240mg IV q2 wk x 6 doses followed by 360mg IV q3 wk x 4 doses followed by 480 mg q4 wk until progressive disease (PD), toxicity, or completion of 96 wks of treatment (Part A). Pts with PD prior to, or stable disease (SD) at 48 wks (pSD) were potentially eligible to receive salvage nivo (3mg/kg)/ipi (1 mg/kg) q3 wk x 4 doses followed by q4 wk nivo maintenance for up to 48 wks (Part B). All pts were required to submit tissue from a metastatic lesion obtained within 12 months (mos) prior to study entry and prior to Part B for correlative studies. Results: 123 pts with clear cell(cc) RCC were enrolled between 5/2017 and 12/2019 at 12 participating HCRN sites. Data lock was 04/07/2021. Median Follow-up 26.9 mos. Median age 65 (32-86) years; 72% male. IMDC risk: favorable (Fav) 35 (28%), intermediate (I) 76 (62%) and poor (P) 12 (10%). 22 (18%) had a component of sarcomatoid histology (SARC). RECIST defined ORR was: 34.1% (25.8-43.2%) (CR 6.5%, PR 27.6%), SD 47 (35.8%). ORR by irRECIST was 39%. ORR by IMDC was: Fav 20/35 (57.1%) (39-74%), (I/P) 22/88 (25%) and for SARC 36.4%. ORR by PD-L1 status was 21/78 (27%), 8/16 (50%) and 6/8 (75%) for pts with tumor PD-L1 of 0, 1-20 or > 20%, respectively (trend test p-value 0.002). 5/7 (71.4%) Fav pts with PD-L1 > 1 responded. Median DOR was 27.6 (13.7, NA) mos with 26/42 responders including 17/20 (85%) with Fav Risk remaining progression free. Median PFS was 8.2 (5.5, 10.9) mos; (30.3 for IMDC Fav and 5.4 for I/P). 91 pts remain alive with 24 mos OS rate of 78%. 65 patients (59 PD, 6 pSD) were potentially eligible for salvage nivo/ipi (Part B), but 25 did not enroll due to symptomatic PD (6), grade 3-4 toxicity on nivo (17), or other (2) and 5 were not treated due to inability to confirm residual disease on a biopsy. ORR for Part B by RECIST was 11.4% (4/35) and by irRECIST 17.2%. Grade 3-5 treatment-related AEs (TrAE) (not including asymptomatic amylase/lipase) were seen in 20.3% in Part A and 14.2% in Part B with 1 death in each cohort. Conclusions: Nivo monotherapy is active in treatment naïve ccRCC across all IMDC groups. Although efficacy appears less than combination nivo/ipi in I/P pts, Fav pts had a notably high ORR and DOR. Efficacy appeared to correlate with tumor PD-L1 status, although at least half the responders had a tumor PD-L1 of 0. Salvage treatment with nivo/ipi after nivo was frequently not feasible and of limited benefit. Clinical trial information: NCT03117309.

Phase II study of nivolumab and salvage nivolumab + ipilimumab in treatment-naïve patients (pts) with advanced non-clear cell renal cell carcinoma (nccRCC) (HCRN GU16-260-Cohort B)

4510

Background: The HCRN GU16-260 trial reported on the efficacy and toxicity of nivo monotherapy in treatment naïve clear cell RCC (Cohort A) and the efficacy of nivo/ipi salvage therapy in pts with tumors resistant to initial nivo monotherapy (Atkins JCO 2020.38.15_suppl.5006). Limited information is available on the effects of such an approach in pts with advanced nccRCC. Methods: Eligible pts with treatment-naïve nccRCC received nivo 240mg IV q2 wk x 6 doses followed by 360mg IV q3 wk x 4 doses followed by 480 mg q4 wk until progressive disease (PD), toxicity, or completion of 96 wks of treatment (Part A). Pts with PD prior to or stable disease (SD) at 48 wks (pSD) were potentially eligible to receive salvage nivo (3mg/kg) /ipi (1 mg/kg) q3 wk x 4 doses followed by q4 wk nivo maintenance for up to 48 wks (Part B). All pts were required to submit tissue from a metastatic lesion obtained within 12 months (mo) prior to study entry and prior to enrolling on Part B for correlative studies. Results: 35 pts with nccRCC were enrolled between 5/2017 and 12/2019 at 12 participating HCRN sites. Median age 63 (range 35-84 years); 89% male. IMDC favorable 8 (23%), intermediate 18 (51%) and poor risk 9 (26%). Of the 35 pts 19 (54%) had papillary, 6 (17%) chromophobe and 10 (29%) unclassified histology. RECIST defined ORR was 5 of 35 (14.3%) [CR 2 (5.7%), PR 3 (8.6%)], SD 16 (45.7%), PD 14 (40.0%). Immune-related ORR was 8 of 35 (22.9%). RECIST ORR by histology was: papillary - 1/19 (5%); chromophobe - 1/6 (17%); unclassified - 3/10 (30%). 9 pts (26%) had tumors with sarcomatoid features with 3 (33%) (2 unclassified, 1 papillary) responding. Median PFS was 4.0 (2.7, 4.3) mo. 21 pts remain alive. None of the responders have progressed or died. 28 pts (25 PD, 3 pSD) were potentially eligible for salvage nivo/ipi (Part B), but 12 did not enroll due to symptomatic PD (2), grade 3-4 toxicity on nivo (3), or other including no biopsy tissue (7). In the 16 Part B pts, best response to nivo/ipi was: PR (1, 6%) – (unclassified/non-sarcomatoid); SD (7, 44%); PD (8, 50%). Grade 3 Treatment-related adverse events (TrAEs) were seen in 7/35 (20%) on nivo. Grade 3-5 TrAEs were seen in 7/16 (44%) on nivo/ipi with 1 pt experiencing sudden death. Correlative studies including PD-L1 status, WES and RNAseq are pending. Conclusions: Nivo monotherapy has limited activity in treatment naïve nccRCC with most responses (4 of 5) seen in pts with sarcomatoid and/or unclassified tumors. Toxicity is consistent with prior nivo studies. Salvage treatment with nivo/ipi was provided in 16 of 28 (57%) pts with PD/pSD on nivo monotherapy, with 1 response observed. Clinical trial information: NCT03117309.

Cyto-KIK: A phase II trial of cytoreductive surgery in kidney cancer plus immunotherapy (nivolumab) and targeted kinase inhibition (cabozantinib)

TPS4598

Background: Despite recent therapeutic advancements in metastatic renal cell carcinoma (mRCC), only 5-10% of patients will achieve a complete response (CR) to therapy. Cytoreductive nephrectomy removes a large portion of the tumor which may be a source of immunosuppression driven by tumor cell-intrinsic factors in the tumor microenvironment. A pre-clinical orthotopic mouse model of aggressive metastatic triple negative breast cancer showed that neoadjuvant anti-PD-1 checkpoint inhibition generated enhanced and sustained antitumor immune responses with improved survival compared to adjuvant therapy (Liu J et al. Cancer Discov. 2016:1382). Clinical validation of improved outcomes with neoadjuvant compared to adjuvant immune checkpoint inhibitors has been demonstrated in trials for patients with non-small cell lung cancer, advanced melanoma, and recurrent glioblastoma (Forde, P.M., et al. N Engl J Med. 2018:1976; Amaria, R.N., et al Nat Med. 2018:1649; Cloughesy T.F., et al. Nat Med 2019:477). Recent data from a phase III trial in subjects with untreated mRCC, demonstrated the superiority of combination cabozantinib and nivolumab over sunitinib and established a new standard of care for mRCC (Choueiri T.K., et al. Annals of Onc, 2020;31 (suppl; abstr 6960). We hypothesize that if tumor specific immune responses to immunotherapy are greatest prior to nephrectomy, then treatment with nivolumab (nivo) and cabozantinib (cabo) prior to cytoreductive nephrectomy will lead to maximal peripheral and intra-tumoral specific immune responses and higher rates of CR during the course of treatment. Methods: This is an open label phase II, multicenter clinical trial of combination nivo and cabo prior to cytoreductive nephrectomy in patients with mRCC (NCT04322955). 48 treatment- naïve subjects with radiological or histological diagnosis of mRCC will be enrolled with the primary endpoint of CR rate according to RECIST version 1.1. Subjects will receive cabo (40mg) daily and nivo (480mg) every 4 weeks for 12 weeks prior to nephrectomy and a 3+3 design will be used to evaluate the safety of the interval (21 or 14 days) between the discontinuation of cabo and nephrectomy. Post-operatively, subjects will resume treatment with cabo and nivo until evidence of disease progression. Secondary endpoints include median size reduction of the primary tumor, response rate, PFS, OS, and surgical outcomes using the Clavien-Dindo classification system. Tissue based assays will quantify treatment related changes in the renal tumor microenvironment through polychromatic immunofluorescence, single cell RNA sequencing of the biopsy and nephrectomy specimen, and multiplex assessment of circulating serum cytokines. Dynamic contrast-enhanced MRI will be performed in a subset of subjects to assess radiologic correlates of response. The study is currently open to enrollment. Clinical trial information: NCT04322955.

The effect of antibiotic use within 30 days of initiation of immune checkpoint inhibitor (ICI) efficacy in patients with metastatic urothelial carcinoma (mUC) in real-world setting

417

Background: There is emerging evidence that patients (pts) treated with immune-checkpoint inhibitors (ICIs) may have a poorer response in the setting of antibiotic use (ABx), possibly due to negative impact on gut microbiota. Our group previously demonstrated that Abx use 60 days before or 60 days in mUC pts after initiation of ICI therapy did not have a significant impact on overall survival (OS) in real-world setting. We now studied the effect of Abx use within 30 days of initiation of ICI on OS in the same cohort of mUC patients. Methods: We performed a retrospective analysis of adult pts with mUC treated at the Cleveland Clinic between 2015 and 2020. Pts included in the study received at least 2 cycles of ICI therapy with either atezolizumab or pembrolizumab. Statistical analysis included study of OS in weeks using the Kaplan Meier method and rank log test, Fischer’s exact test, and Kruskal-Wallis test. Results: A total of 115 pts that received ICI therapy were included. 57 pts received atezolizumab and 58 pts received pembrolizumab. 38 pts (33%) received antibiotics and 77pts (67%) did not. The most commonly used Abx used were Cephalosporins (27%), Penicillins/Carbapenems (25%), Flouroquinolones (23%), and Bactrim (11%). 18 pts received Abx within 30 days before initiation of ICI, 13 pts received Abx within 30 days after initiation of ICI, and 7 pts received Abx before and after initiation of ICI. There was no statistical difference in OS in the group of pts that received Abx 30 days prior to initiation of ICI with median OS of 5.95 months (95% CI 3.22-13.67, p=0.0695) compared to 12.39 months (95% CI 10.09 – 18.6) in those who did not receive Abx. Similarly, there was no statistical difference in OS in the group of pts that received Abx 30 days after initiation of ICI with median OS of 5.09 months (95% CI 2.53-22.57, p=0.2339) compared to 12.02 months (95% CI 8.6`-17.02 Table). Conclusions: In our single institution study of mUC patients receiving ICI treatment, the use of Abx did not affect the OS. Although there was a trend for better OS seen in pts who did not receive Abx, it was not statistically significant (Table). Due to the limitations of a retrospective analysis and small sample size, further studies are warranted taking into account other factors that may affect gut microbiota in mUC pts. [Table: see text]

Phase II trial of cytoreductive surgery in kidney cancer plus immunotherapy (nivolumab) and targeted kinase inhibition (cabozantinib) (Cyto-KIK)

TPS371

Background: Despite recent therapeutic advancements in metastatic renal cell carcinoma (mRCC), only 5-10% of patients will achieve a complete response (CR) to therapy. Cytoreductive nephrectomy removes a large portion of the tumor which may be a source of immunosuppression driven by tumor cell-intrinsic factors in the tumor microenvironment. A pre-clinical orthotopic mouse model of aggressive metastatic triple negative breast cancer showed that neoadjuvant anti-PD-1 checkpoint inhibition generated enhanced and sustained antitumor immune responses with improved survival compared to adjuvant therapy (Liu J et al. Cancer Discov. 2016:1382). Clinical validation of improved outcomes with neoadjuvant compared to adjuvant immune checkpoint inhibitors has been demonstrated in trials for patients with non-small cell lung cancer, advanced melanoma, and recurrent glioblastoma (Forde, P.M., et al. N Engl J Med. 2018:1976; Amaria, R.N., et al Nat Med. 2018:1649; Cloughesy T.F., et al. Nat Med 2019:477). Recent data from a phase III trial in subjects with untreated mRCC, demonstrated the superiority of combination cabozantinib and nivolumab over sunitinib and established a new standard of care for mRCC (Choueiri T.K., et al. Annals of Onc, 2020;31 (suppl; abstr 6960). We hypothesize that if tumor specific immune responses to immunotherapy are greatest prior to nephrectomy, then treatment with nivolumab (nivo) and cabozantinib (cabo) prior to cytoreductive nephrectomy will lead to maximal peripheral and intra-tumoral specific immune responses and higher rates of CR during the course of treatment. Methods: This is an open label phase II, multicenter clinical trial of combination nivo and cabo prior to cytoreductive nephrectomy in patients with mRCC (NCT04322955). 48 treatment- naïve subjects with radiological or histological diagnosis of mRCC will be enrolled with the primary endpoint of CR rate according to RECIST version 1.1. Subjects will receive cabo (40mg) daily and nivo (480mg) every 4 weeks for 12 weeks prior to nephrectomy and a 3+3 design will be used to evaluate the safety of the interval (21 or 14 days) between the discontinuation of cabo and nephrectomy. Post-operatively, subjects will resume treatment with cabo and nivo until evidence of disease progression. Secondary endpoints include median size reduction of the primary tumor, response rate, PFS, OS, and surgical outcomes using the Clavien-Dindo classification system. Tissue based assays will quantify treatment related changes in the renal tumor microenvironment through polychromatic immunofluorescence, single cell RNA sequencing of the biopsy and nephrectomy specimen, and multiplex assessment of circulating serum cytokines. Dynamic contrast-enhanced MRI will be performed in a subset of subjects to assess radiologic correlates of response. The study is currently open to enrollment. Clinical trial information: AAAS6927 .

Impact of primary tumor location, histology, and host factors on objective response to immune checkpoint inhibitors in metastatic urothelial carcinoma

493

Background: Factors affecting response to immune checkpoint inhibitor (ICI) are poorly understood in metastatic urothelial carcinoma (mUC). While tumor PD-L1 status is often used as a biomarker, it is not always predictive and ICI also benefits patients (pts) with PD-L1 negative tumors. Therefore, we sought to study the effect of some host and disease-related variables like gender, ethnicity, body mass index (BMI), platelet to lymphocyte ratio (PLR), and neutrophil to lymphocyte ration (NLR) on objective responses in pts with mUC treated with ICI. Methods: We performed a retrospective analysis of adult pts with mUC who received ≥2 cycles of ICI (pembrolizumab or atezolizumab) at the Cleveland Clinic from 2015 to 2020. Tumor and host-related factors evaluated are listed in the table below. We focused on meaningful treatment response, so only partial response (PR) and complete response (CR) were included as responders, while stable disease (SD) and progressive disease (PD) were counted as non-responders. Analysis was carried out with Fisher’s exact test and Wilcoxon rank sum test as applicable. Results: A total of 124 pts with mUC that received ICI were included. Gender did not correlate with response (p>0.99) or duration of response (p=0.37). Ethnicity did not correlation with response (p=0.78) or duration of response (p=0.24). Histology (UC, mixed variant histology or non UC) did not correlate with response (p=0.13) or duration of response (p=0.87). Location of primary malignancy (upper tract versus lower tract) did not correlate with response (p>0.99) or duration of response (p=0.36). BMI (p=0.23), PLR (p=0.9), and NLR (p=0.9) did not correlate with objective response. Conclusions: In our single center experience of pts with mUC treated with ICI, host factors (gender, ethnicity, histology, BMI, NLR, PLR) and location of primary tumor did not correlate with treatment response or duration of response. Although there were few African Americans represented in this study as commonly seen for minority representation, it is encouraging that no significant differences in responses were observed. The role of BMI and gender in response to ICI treatment in mUC was not observed. While there are limitations of a retrospective analysis, our study warrants investigation into predictive factors of response to ICI in mUC. Ongoing work integrating radiomics and pathomics will further our understanding and develop potential predictive biomarkers of response to ICI in mUC. [Table: see text]

Safety and efficacy outcomes in immune checkpoint inhibitor (ICI)-treated metastatic urothelial carcinoma (mUC) patients (pts) requiring treatment interruption (TI) due to immune-related adverse events (irAEs)

411

Background: Most patients (pts) with metastatic urothelial carcinoma (mUC) will receive immune checkpoint inhibitors (ICI) at some point during treatment. As such, understanding of immune-mediated toxicity is integral to optimal patient management. We describe the clinical characteristics, treatment, and outcomes of ICI-treated mUC pts who experienced irAEs requiring treatment interruption (TI). Methods: ICI-treated mUC pts who developed > grade 2 (per CTCAEv5) irAEs leading to >2 week TI were retrospectively reviewed. Patient-, disease-, treatment-, and toxicity-related data were evaluated. Toxicity was graded per CTCAEv5. Time to treatment interruption (TTI), treatment-free interval (TFI), time to next treatment (TTNT), and duration of response (DoR) were assessed descriptively. Results: Of 200 ICI-treated mUC pts, 18 (9%) experienced irAEs necessitating TI. 12 (43%) were male; median age at diagnosis was 72.5 (range, 45-80); 15 (83%) had KPS > 80. 8 (44%) had pure UC histology, 14 (78%) had prior cystectomy or nephroureterectomy, and 11 (61%) received platinum-based chemotherapy in the perioperative setting. 4 (22%) received 1L platinum-based Tx for mUC. ICI therapy was distributed evenly between atezolizumab (50%, n = 9) and pembrolizumab (50%, n = 9). Median TTI was 6.5 months (mos) (range, 1-19). The most common irAEs were dermatitis (22%, n = 4), colitis (17%, n = 3), and transaminitis (17%, n = 3); the majority were grade 2 (72%, n = 13). No grade 4/5 events occurred. 14 pts (78%) were treated with methylprednisolone and/or prednisone. Median initial prednisone-equivalent steroid dose was 45 mg/day (range, 30-1,250) with a median steroid duration of 42 days (range, 4-198). ICI were held and later re-challenged in 10 pts (56%), permanently discontinued in 7 pts (39%), and transitioned to a subsequent Tx in 1 pt (5%). Of 10 pts re-challenged with ICI, 7 (70%) experienced an irAE upon re-challenge (4 with recurrent irAEs, 3 with new irAEs); ICI was permanently discontinued in 3 of these pts. For pts receiving subsequent Tx, median TFI was 1 month (range, 0-12) and median TTNT was 5 mos (range, 2-31). Median DoR among all pts with initial response to ICI therapy was 15.5 mos (range, 2-52). Of 7 pts who permanently discontinued ICI and received no further Tx, 6 (86%) demonstrated an ongoing sustained therapy response with median DoR of 22.5 mos (range, 12-52). Conclusions: In this cohort, ICI-treated mUC pts who developed irAEs requiring treatment interruption had a high rate of subsequent irAEs upon ICI re-challenge. Importantly, pts who discontinue ICI due to irAE can have durable responses off treatment, consistent with data from other cancers.

Thromboembolism (TE) in patients (pts) with bladder cancer treated with checkpoint inhibitors (CPIs)

5042

Background: Most pts with bladder cancer will be treated with immunotherapy. There is concern for increased TE risk with CPIs in this already high risk population. We present the first analysis of the incidence and outcomes of venous (VTE) and arterial (ATE) thromboembolism in pts with bladder cancer treated with CPIs. Methods: Consecutive pts with bladder cancer treated with CPIs at the Cleveland Clinic from 1/2015 to 12/2019 were identified and TE events noted. Overall survival (OS) was estimated using Kaplan-Meier method and the impact of VTE on OS was evaluated using Cox proportional hazards regression. Results: Of 274 pts, 72% were men (median age 73.3 years, 89% white), 82% had pure UC, 92% had lower tract disease, and 67% had a Bajorin score ≥1 (median KPS 90, 61% visceral metastases), 59% had prior systemic therapy (median 1, range 0-4) and 36% had prior TE (14% ATE, 19% VTE, 0.4% both). At CPI initiation, 24% were on antiplatelet therapy, and 15% on therapeutic anticoagulation. CPI (median doses 5, range 8.5-59) included: 40% atezolizumab, 3% nivolumab, 57% pembrolizumab. VTE occurred in 14% (n = 37), including 8% DVT, 4% PE, 2% both. DVT locations were 56% lower limb, 26% upper limb, 15% visceral vein, 4% visceral+upper limb. 2% (n = 5) had ATE (1% CVA, 0.4% visceral, 0.4% left subclavian). 92% of VTE and all ATE occurred within 6 months of CPI initiation. The incidence of TE was 10.9% (95%CI 6.6%—15.1%) at 6 months and 19.8% (95%CI 13.3%-26.4%) at 12 months. 82% of VTE (mean 6 days) and all ATE (mean 5 days) resulted in hospitalization. Multivariate analysis showed TE (HR 2.296, 95%CI 1.451-3.632, p = 0.0004), Bajorin score 1 (HR 1.490, 95%CI 1.036-2.142, p = 0.0315), and Bajorin score 2 (HR 3.50, 95%CI 2.14-5.74, p < 0.0001) were independently associated with worse OS. Conclusions: CPIs in bladder cancer pts are associated with a high TE risk, especially within six months of initiation. TE is associated with worsened survival. Further investigation into the risk factors for CPI-associated TE is needed to identify if benefits exist from thromboprophylaxis.

A phase Ib trial of neoadjuvant/adjuvant durvalumab +/- tremelimumab in locally advanced renal cell carcinoma (RCC)

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Background: Effective neoadjuvant and adjuvant therapies are lacking in locally advanced RCC. Given robust activity of checkpoint inhibitors in mRCC, a phase Ib trial of perioperative Durvalumab (D) +/- Tremelimumab (T) in locally advanced RCC was conducted (NCT02762006). Methods: Pts with radiographic evidence of high risk localized RCC (clinical stage T2b-4 and/or N1, M0 disease), adequate performance status, and adequate laboratory values were eligible. Primary objective was safety and feasibility of neoadjuvant/adjuvant D +/- T. Results: Twenty-nine pts were enrolled. Cohorts, regimens, and immune-related adverse events (irAE) are detailed in the table. In total, 79% male, median age 61 (range, 42-84), 8%/88%/4% clinical T2/T3/T4, 27% positive clinical lymph nodes (LN+), and median time from neoadjuvant dose to surgery was 7 days. On surgical pathology: 5%/14%/77%/5% pathologic T1/T2/T3/T4, and 13% LN+. Median time from treatment to first grade (Gr) >3 irAE or any Gr irAE requiring corticosteroids was 99 days (range, 32-207). There were no treatment-related delays to nephrectomy or surgical complications. Although not meeting the protocol-defined MTD, given higher than expected irAEs, the study was suspended. Conclusions: Perioperative durvalumab in locally advanced RCC appears safe. The addition of tremelimumab is associated with higher rates of toxicity. Updated toxicity will be presented. Clinical trial information: NCT02762006 . [Table: see text]

Early PSA decline as a predictor of progression in patients with metastatic castration-naïve prostate cancer (mCNPC) treated with abiraterone acetate and prednisone (AA/P)

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Background: Treatment intensification with androgen deprivation therapy (ADT) plus AA/P is a standard of care in patients with metastatic castration naïve prostate cancer (mCNPC). Despite initial responses, nearly all men will eventually progress to castration resistant disease (CRPC). Early changes in PSA while on ADT plus AA/P has significant clinical and therapeutic implications for mCNPC patients, yet limited data is available. We aimed to assess PSA patterns while on therapy with ADT plus AA/P and time to CRPC. Methods: mCNPC patients treated with ADT plus AA/P between June 2017 and February 2019 at the Cleveland Clinic, were included. The primary objective was to describe patterns of PSA change evaluated using a longitudinal mixed model at time 0, 3, 6, 9, and 12 months from AA/P initiation. Other endpoints of interest included PSA progression by PCWG3 and CRPC-free survival at 12 and 18 months. Results: A total of 130 patients, 82% Caucasian, median age 69 years, with 50% with de-novo mCNPC, 47% high-volume (60.8% Gleason score ≥8, 16.2% visceral disease, and 53.8%had ≥3 bony lesions) were included. Half of the patients achieved undetectable PSA ( < 0.03) while on therapy. The median time to PSA < 0.03 was 13.1 months (95%CI, 7.6-NE). The greatest PSA reduction occurred at the first 3 months (80%, p < 0.0001), changes after 3 months were small, (4% from 3 to 6 months, p < 0.0001; 3% from 6 to 9 months, p < 0.0001) and not significant from 9 to 12 months. The 12 and 18-months mCRPC-free survival after initiation of ADT plus AA/P was 88.1% and 81.3%, respectively. A PSA > 0.2 at 3 months was associated with a shorter time to mCRPC (p = 0.002). Similarly, a PSA reduction < 98% at 3 months was associated with worse outcomes (12 mo CRPC survival 68.0% vs. 94.9%, respectively; p < 0.001). Conclusions: In this data set, timing and depth of serologic response predicted the early development of CRPC in patients receiving ADT plus AA/P. Further validation is ongoing using data from large randomized clinical trials.

Response to checkpoint inhibitors (CPI) in sarcomatoid renal cell carcinoma (sRCC)

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Background: sRCC have a generally poor prognosis though recent clinical trial data suggest improved outcomes with CPI. We present a real-world experience of metastatic sRCC patients (pts) treated with a variety of CPI. Methods: Pts with sRCC treated with CPI Cleveland Clinic from 1/1/2015 to 12/31/2019 were identified. Overall survival (OS) was estimated using Kaplan-Meier and compared by log rank test. Results: Of 28 eligible pts identified with sRCC, median age 58, 82% Caucasian, all KPS score > 80%, 86% had IMDC intermediate/poor risk disease, 75% were clear cell, and 71% had prior nephrectomy. 46.4% had prior non-CPI systemic therapy. CPI therapy in this cohort included: 46% nivolumab monotherapy, 18% axitinib/pembrolizumab, 21% ipilimumab/nivolumab, 4% atezolizumab/bevacizumab, 7% atezolizumab, 4% carboplatin/pemetrexed/pembrolizumab. At a median follow up of 13.6 months (range 6.5-31.4), ORR was 36% (4% CR, 32% PR) and median OS was 13.8 months (95% CI: 9.23-NA). Median time to response was 3.2 months (range 2.4-13.1) and median duration of response was 8.1 months (range 0-25.5). Ten of the 13 patients started subsequent therapy due to progression. At the time of analysis, 39% were still alive and 25% of patients were still on initial I/O therapy (7+ -30+ months). There were no clear correlations between specific disease-related factors (including IMDC risk, time-to treatment of > or < 1 year, or prior systemic therapy) and response (all were p > 0.05). Conclusions: ORR and CR rates were lower in this real-world population of metastatic sRCC pts compared to clinical trial data, which should be a result of various CPI treatments and lines of treatment. However, these data highlight the heterogeneity of sRCC in general and need for additional investigations into impact of percentage of sarcomatoid features, genomic analyses, line of therapy, and CPI choice to optimize outcomes in sRCC pts.

Gender impact on renal cell carcinoma survival: A population-based analysis

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Background: Prior evidence has suggested that females diagnosed with renal cell carcinoma (RCC) present at an earlier stage compared to males, but a survival difference between males and females has been controversial. We aimed to evaluate the impact of gender on RCC survival in the US. Methods: Data of RCC patients diagnosed between 1973 and 2015 in the US was obtained using Surveillance Epidemiology and End Results (SEER) database. We studied the overall and cancer-specific survival of patients diagnosed with RCC in the US according to gender using multivariable covariate-adjusted Cox models and Kaplan-Meier test. Results: We reviewed 155,430 RCC patients, of which 96,656 were males, and 58,774 were females. The median overall survival of female patients was 122 months and was significantly higher than male patients (98 months). Cancer-specific survival showed similar trends with females having significantly higher survival (p-value < 0.001). Adjusted for age, race, stage and grade of cancer, undergoing cancer-targeted surgery, and marital status, female sex was associated with improved overall and cancer-specific survival outcomes; HR = 0.829 (p-value < 0.001), and HR = 0.923 (p-value < 0.001), respectively. Conclusions: Females have a significantly better overall and cancer specific survival compared to males diagnosed with renal cell carcinoma. In previous studies this disparity was attributed to the lower grade and earlier stage of RCC presentation in females, but gender-based disparity persisted in this analysis after adjusting for patient baseline and tumor characteristics. This raises the question of the hormonal effects on the progression of RCC.

Retrospective analysis of immune-related adverse events (irAE) in metastatic renal cell carcinoma (mRCC) patients treated with first-line ipilimumab and nivolumab (I+N)

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Background: Incidence of irAEs has grown with increasing use of immunotherapies and can affect multiple organ systems: I+N followed by N maintenance is approved as front-line therapy for intermediate & poor-risk mRCC. Most common associated irAEs are gastrointestinal, dermatologic & hepatic. The purpose of this retrospective, single-institution analysis is to describe irAE incidence and identify risk factors in mRCC pts treated with I+N. Methods: Patients with mRCC started on first-line I+N at the Cleveland Clinic between March 2018 and April 2019 were retrospectively reviewed. Patient demographics, tumor characteristics, radiologic response and irAE history were collected. IRAE incidence was estimated with cumulative incidence. Risk factors for IRAE were assessed with Fine and Gray competing risk regression. Results: Of forty-six (N = 46) pts with mRCC treated with 1L I+N, median age 60 (range: 34-81): 95% clear cell histology; IMDC risk 20%/56%/24% favorable/intermediate/poor respectively. 67% (N = 31) experienced ≥ 1 irAE with total of N = 44 irAEs. Most common systems affected included Gastrointestinal (27%), Musculoskeletal (23%), Dermatologic (14%) & Renal (9%). Most common irAEs were colitis (23%), arthralgia (16%), transaminitis (9%). 82% of irAEs were treated with front-line glucocorticoids and 14% required additional immunosuppressants. 82% of irAEs were attributed to the I+N induction phase and 32% required discontinuation of I+N. 1 pt died as result of irAEs. Incidence of irAEs at 1, 3 and 6 months was 20%, 52%, 59% respectively. Among 31 pts who developed irAEs, median onset from start of I+N was 1.6 months (range 0-11.7). None of the variables examined (i.e. age at I+N initiation, gender, race, IMDC risk, ECOG status, stage at diagnosis, prior nephrectomy, prior radiation therapy) were identified as statistically-significant risk factors for irAEs. Development of irAEs was not associated with progression-free survival (PFS). Conclusions: IRAEs from I+N in mRCC tend to occur early in treatment course and are associated with high rates of treatment discontinuation and need for corticosteroids and other immunosuppressants. The lack of association between baseline factors and development of irAEs should increase physician alertness to potential irAEs with any change in clinical status.

Impact of preoperative neutrophil to lymphocyte ratio (NLR) and platelet to lymphocyte ratio (PLR) on overall survival or recurrence free survival in muscle-invasive bladder cancer at cystectomy

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Background: The role of Neutrophil to Lymphocyte Ratio (NLR) and Platelet to Lymphocyte Ratio (PLR) in prognostication of MIBC is not clearly understood. There is growing evidence that, as markers of inflammation, they may have prognostic utility in MIBC at radical cystectomy (RC). Methods: We performed a retrospective analysis of MIBC patients who underwent RC at the Cleveland Clinic from 2/2015 to 1/2018. 84 patients were identified who were either diagnosed with TaN0M0 treated with Neoadjuvant Chemotherapy (NAC) or T1-T4N0M0 disease treated with or without NAC. For NAC, 27 patients received gemcitabine and cisplatin, 2 patients received gemcitabine and carboplatin, 4 patients received unknown regimen, and 3 patients received MVAC. Of the patients, there were 1 with Ta, 34 with T1, 44 with T2, 1 with T3 and 4 with T4 disease. Complete Blood Count with Differential closest to or on the day of resection was used. NLR and PLR were calculated by dividing Absolute Neutrophil Count and Platelet Count by the Absolute Lymphocyte Count, respectively. PLR and NLR were dichotomized at the median. Outcomes were analyzed via Kruskal-Wallis test. Results: Median follow up of patients was 28.8 months. Median NLR and PLR were 15.7 and 263, respectively. Mean NLR and PLR were 18.9 and 310, respectively. NLR and PLR did not correlate with overall survival, recurrence free survival, T or N stage post resection, or pathological response. Females were found to have a higher NLR than males. Conclusions: Contrary to previous reports, our study did not find any prognostic value of NLR and PLR in MIBC patients at RC. Further evaluation of PLR and NLR in MIBC and correlation with molecular features may help understand its potential prognostic role in patients undergoing surgical resection.

The effect of antibiotic use on immune-checkpoint inhibitor efficacy in patients with advanced urothelial carcinoma

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Background: There is emerging evidence that antibiotic (Abx) use may be associated with poor response to immune-checkpoint inhibitors (ICIs) in patients (pts) with some solid tumors. However, this has not been studied in metastatic urothelial carcinoma (mUC). We examined the effect of Abx use on outcomes in pts receiving ICIs for mUC. Methods: We retrospectively reviewed adult pts receiving ICIs for mUC treated at Cleveland Clinic between 2015 and 2020. Pts included in the study received > / = 3 cycles of ICI therapy with either azetolizumab or pembrolizumab. Abx use was defined as at least 3 days of Abx in the 60 days preceding or following ICI initiation. PFS and OS were estimated using the Kaplan-Meier method and a Cox proportional hazard model was used to calculate hazard ratios (HRs) and 95% confidence intervals (CI). Results: A total of 69 pts with mUC receiving ICI therapy were included. The Abx-treated group consisted of 22 pts (32%) and the Abx-untreated group was 47 pts (68 %). 30 pts had Abx 60 days prior to ICI initiation and 20 patients had Abx within 60 days of ICI initiation. Abx use 60 days prior to ICI was not associated with PFS (HR = 0.91, 95% CI = 0.42-1.95) or OS (HR = 0.52, 95% CI = 0.33-1.68). Abx use during the first 60 days of ICI use was associated with decreased PFS (HR = 2.23, 95% CI = 1.03-4.86) but not OS (HR = 2.01, 95% CI = 0.89-4.53). Notably, there was no effect on response rates. The most commonly used Abx prior to treatment were: fluoroquinolones (30%); cephalosporins (26%); non-cephalosporin beta lactams (17%); and trimethoprim-sulfamethoxasole (13%). The most commonly used Abx after treatment initiation were: fluoroquinolones (17% of patients); cephalosporins (13%); non-cephalosporin beta lactams (12%); and trimethoprim-sulfamethoxasole (9%). Our study was insufficiently powered to address the effect of different antibiotic classes on outcomes. Conclusions: In our study, Abx use within first 60 days of treatment with ICIs was associated with decreased PFS and a trend toward decreased OS in pts with mUC but not in pts receiving Abx 60 days prior to ICI therapy. While the numbers are small, this is the first report exploring the effect of Abx on ICI response in mUC and further studies in larger databases are warranted.

A novel orthotopic murine model of neuroendocrine bladder cancer: Insights into the phenotypic plasticity of small cell bladder cancer (SCBC)

571

Background: SCBC is an aggressive subtype of bladder cancer with high metastatic potential and few effective treatment options. We developed an orthotopic mouse model of SCBC to understand the development of this rare bladder cancer variant and identify epigenetic drivers of neuroendocrine differentiation. Methods: Lentiviral particles carrying Cre recombinase were produced using Lenti-sgNeo#2/Cre. The bladders of Rb1fl/fl Trp53fl/fl MycLSL/LSL (RPM) mice was transduced with Cre recombinase expressing lentivirus via transurethral catheterization. Mice were monitored by micro-ultrasound (mUS) and detected tumors were verified by histology. SCBC morphology was confirmed by H&E staining and synaptophysin IHC. Whole transcriptome (RNAseq) analysis was performed to correlate transcriptomic profile of neuroendocrine mouse tumors to a cohort of human SCBC tumors. Results: Transurethral catheterization successfully transduced the bladder urothelium without evidence of exposure of ectopic (non-urothelial) tissues. RPM mice developed SCBC visible on mUS with a latency of 8-10 weeks. As expected in neuroendocrine tumors, mice developed liver and lung metastases. High grade neuroendocrine morphology and NE markers were confirmed on H&E and IHC, respectively, by a GU pathologist. Western blot analysis confirmed cMyc expression and suppression of TP53 and RB1. Synaptophysin expression was confirmed by IHC. Transcriptomic profiling of both mouse and human SCBC demonstrated concordant gene expression. Gene expression profiling of urothelial and non-urothelial neuroendocrine tumors suggested a phenotypic convergence. Conclusions: We developed a novel genetically engineered murine model of SCBC. Ongoing work seeks to identify epigenetic markers playing role in the development of this aggressive variant of bladder cancer. We are assessing the activity of immune checkpoint inhibitors in this immunocompetent background.

Tumor cell intrinsic androgen biosynthesis by 3β-hydroxy steroid dehydrogenase (HSD3B1) to modulate radiosensitivity in prostate cancer cells

349

Background: Resistance to ADT is associated with a gain of function mutation in the 3β-HSD enzyme, which catalyzes extragonadal/intratumoral DHT synthesis. As androgen signaling is known to upregulate the DNA damage response (DDR), we investigated whether HSD3B1 genotype modulates DDR and radiosensitivity in PCa. Methods: We stably knocked down HSD3B1 in LNCaP, C42 and VCaP cell lines (which carry the protein stabilizing variant allele) and overexpressed the variant HSD3B1 allele in LAPC4 (harbors a WT allele which readily undergoes degradation). We examined the proliferative and clonogenic capacity of these cells in presence and absence of substrate, DHEA, followed by treatment with IR (400-800 cGy, single fraction). We studied DNA DSB formation and resolution kinetics using γH2AX foci formation in response to radiation. We also measured changes in mRNA expression of DDR response genes pre- and post-radiation. Results: Control shRNA transduced cell lines had increased cell proliferation (p<0.001) and clonogenic survival (2 logs at 800cGy single fraction radiation, p<0.001) in the presence of DHEA compared to HSD3B1 knockdown cells. Variant HSD3B1 cell lines were more radioresistant and exhibited more efficient γH2AX foci resolution at 24 hrs (p <0.05) in a DHEA dependent manner. We observe increased mRNA expression of DDR genes from specific repair networks including non-homologous end joining (PRKDC, XRCC4, XRCC5) and homologous recombination (RAD51, RAD54) in variant HSD3B1 cells. Transcriptional induction of DDR genes following radiation in presence of DHEA was significantly more pronounced in HSD3B1 variant cells, suggesting a more permissive chromatin context. Conclusions: Increased intracellular 3β-HSD drives transcription of NHEJ and HR genes, more rapid resolution of γH2AX foci, and radioresistance in prostate cancer. This work has therapeutic implications related to strategies for combined radiation and androgen directed therapy in localized and metastatic prostate cancer. Prospective validation of treatment strategies combining blockade of adrenal steroid precursor synthesis, ADT, and XRT in high risk disease is warranted.

Racial disparities in the outcomes of transitional cell carcinoma of the bladder: A population-based analysis

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Background: Bladder cancer is the most common type of genitourinary malignancy and is the fourth most common cancer in men in the US. Transitional cell carcinoma (TCC) of the bladder accounts for most bladder cancer cases. Previous studies have observed racial disparities in the prognosis between white and black populations with very little mentioned about other ethnicities and race groups that are part of the United States population. We hereby, present a detailed and comprehensive analysis of racial disparities in TCC survival in the US. Methods: Using the data from surveillance Epidemiology and End results (SEER) database, we identified patients with TCC between 1992 and 2015. We used multivariable covariate-adjusted Cox models to analyze the overall and TCC-specific survival of patients according to their race. Results: We evaluated 176,388 patients with TCC and after we adjusted for age, sex, race, stage, grade, and undergoing cancer-targeted surgery, we found that Asians/Pacific Islanders and Hispanics had a better overall survival when compared to whites (HR= 0.792, 95% CI [0.761-0.824], P<.001 and HR = 0.941, 95% CI [0.909-0.974], P = .001, respectively). Asians/Pacific Islanders also showed better TCC specific survival (HR = 0.843, 95% CI [0.759-0.894], P<.001). Blacks had worse overall survival and TCC-specific survival (HR =1.221, 95% CI [1.181-1.262], P <.001 and HR =1.325, 95% CI [1.268- 1.384], P <.001, respectively). When stage IV TCC was analyzed separately, only Hispanics showed better overall and TCC specific survival when compared to whites (HR = 0.896, 95% CI [0.806-0.997], P = 0.044 and HR = 0.891, 95% CI [0.797-0.996], P = 0.42). Conclusions: Asians/Pacific Islanders have better overall and TCC-specific outcome while blacks have the worst outcome compared to whites. Hispanics have better overall and cancer specific survival in stage IV TCC. These disparities likely related to different and complex factors from lifestyle and chemical exposure to genetic factors. Further studies can help us more in understanding and approaching this malignancy in different race groups.

The association between PSA pattern changes and progression in patients with metastatic hormone-sensitive prostate cancer (mHSPC) treated with abiraterone and prednisone (AA/P)

18

Background: Despite treatment with AA/P, many patients with mHSPC will develop castrate resistant disease (CRPC). Early recognition of progression is difficult. Changes in PSA patterns in patients with mHSPC treated with AA/P may help identify evolution to mCRPC. Methods: All patients with mHSPC who initiated ADT and AA/P from June 2017 to February 2019 at the Cleveland Clinic were eligible. Patterns of PSA change were evaluated using a longitudinal mixed model at time 0, 3, 6, 9, and 12 months (mo) from AA/P initiation. Time to PSA<0.03 and CRPC were estimated using Kaplan-Meier method. Progression was defined as a PSA rise at two consecutive time points. Results: Of the 143 patients who initiated AA/P, 134 men (median Gleason score 8, baseline PSA 15.0 ng/mL) with follow up were included. 52% had de novo mHSPC, 47.8% had prior therapy (21% surgery, 20% radiation, 7% both), and 16% had visceral disease. PSA levels dropped 98.2% in the first 3 mo (p<0.001), slowed from 3-9 mo (p<0.05) and plateaued after 9 mo. The % PSA reduction from time 0 to the other time points was small. The median time to PSA<0.03 was 11 mo. Of those who progressed to CRPC, the reduction within the first 3 mo was more significant than in those who did not (Table). Measurable PSA was higher in patients who progressed to CRPC at all-time points and plateaued by 6 mo. 12-mo CRPC-free after AA/P was 86.7% (95% CI: 79.2, 94.1). Patients with ≥ 98% 3-mo PSA reduction had better CRPC-free survival than patients with <98% reduction (12-mo CRPC-free: 94.4% vs 78.4%), p<0.001. Conclusions: The degree of PSA decline within 3 mo of AA/P may be used as treatment efficacy measurement. Tracking PSA pattern changes may alert clinicians for potential progression, consider frequent PSA and imaging, as well as initiate sequential therapy.[Table: see text]

Genitourinary oncology referral patterns to the cancer associated thrombosis clinic: The Cleveland Clinic experience

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Background: Cancer related thrombosis affects ~20% of all cancer patients. It is our standard practice to refer cancer patients with suspected venous thromboembolism (VTE) to our Cancer Associated Thrombosis (CAT) clinic. Referrals are based on a clinical suspicion of VTE or a Khorana score ≥3. We sought to evaluate the characteristics of patients with genitourinary (GU) cancer referred to the CAT clinic and their association with immunotherapy. Methods: The study population comprised of all cancer patients referred to the CAT clinic with a diagnosis of prostate cancer (Pca), bladder cancer (BC) or renal cell cancer (RCC) from August 1, 2014 to October 15, 2019. Results: Of the 147 patients with GU cancers referred to CAT clinic, 43 had a VTE (14/40 BC, 14/44 RCC, 15/63 PCa). Of which, 83% were DVT, 5% were PE, and 12% had both. The majority had stage 4 disease (98%), no prior clotting history, and ECOG 0-2 (86%). Average BMI was 28.63 and 22 patients had smoking histories (average 11 pack years). Major histology per cancer type were adenocarcinoma (100%) in PCa, 86.7% clear cell in RCC and 85.7% urothelial carcinoma in BC. Lower extremity pain or swelling (67%) was the major reason for referral. Thirty-four of the 43 patients were on active treatment; 7 patients on immunotherapy (average 4.9 months) and 13 patients on chemotherapy (average 2.6 cycles) at the time of VTE diagnosis. Of the chemotherapy regimens, patients were on the combination of gemcitabine with carboplatin (54%), docetaxel (23%), or cabazitaxel (23%). Atezolizumab was the most commonly used immunotherapy agent (57%). Other immunotherapy agents associated were nivolumab (29%) and the combination of ipilimumab with nivolumab (14 %). There was no VTE-related mortality. Conclusions: Our single center experience shows 16% of VTE events in patients with GU cancers were associated with immunotherapy and 33% were associated with cytotoxic chemotherapy. There is a growing body of literature exploring the association between thromboembolic events and immunotherapy. As more patients with GU cancers are treated with immunotherapy, it will be interesting to see how this influences the rate of CAT clinic referral and prevalence rates of VTE.

Multicenter retrospective analysis of patients with metastatic renal cell carcinoma (mRCC) and bone metastases treated with ipilimumab and nivolumab

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Background: Ipilimumab & nivolumab (I+N) followed by nivolumab maintenance is approved as front-line therapy for intermediate and poor-risk metastatic renal cell carcinoma (mRCC). Bone metastases (BM) are present in up to 30% of mRCC patients (pts) and remain a clinical challenge. We present a multicenter experience of mRCC pts with BMs treated with I+N. Methods: Patients with mRCC and bone metastases treated with (I+N) at Duke Cancer Network and Cleveland Clinic were retrospectively reviewed. Patient demographics, tumor histology, IMDC risk stratification, RECIST-defined ORR and adverse events were collected. Fisher’s exact test was used to determine predictors of response (alpha 0.05). Results: Forty-eight pts with mRCC and radiographically confirmed BMs were included in the analysis: 81% male; median age 54 (range: 41-81); 77% clear cell histology; IMDC risk 17%/52%/31% favorable/intermediate/poor, respectively. I+N was used as first-line medical therapy in 63% of pts and ≥ second-line in remaining pts. Best response on I+N per RECIST criteria: objective response rate (ORR) 23% (0% CR); 23% stable disease (SD); 44% progressive disease (PD). Median duration of treatment was 64 days with 27% of pts still on I+N. PD was the most common reason for discontinuation (38%) followed by adverse events (19%). Nearly half of pts (48%) experienced at least one irAE attributed to I+N therapy. None of the factors examined above was significantly associated with response to treatment. Conclusions: I+N has clinical activity and is well tolerated in mRCC pts with bone metastases; however ORR in this population is lower than expected and 44% pts had PD as best response. Therefore, identifying prognostic factors & improving novel therapies for this cohort of patients are priorities, given overall poorer outcomes in this population.

The impact of marital status on the survival of transitional cell carcinoma of the bladder

578

Background: Marital status is one of the multiple lifestyle factors that affect the survival of several malignancies. Prior literature has demonstrated that married individuals have better survival in cases of transitional cell carcinoma (TCC). In this study, we aim to demonstrate the association in a large cohort of patients. Methods: Data of TCC patients with known marital status who were diagnosed between 1973 and 2015 in the US was obtained using the Surveillance Epidemiology and End Results (SEER) database. We compared the overall and cancer-specific survival of patients according to their marital status using Kaplan-Meier test and multivariable covariate-adjusted Cox models. Results: We reviewed 204,862 TCC patients, of which 64.26%, 10.64%, 1.01%, 7.31%, and 16.78% were married, single, separated, divorced, and widowed, respectively. Married patients had the highest overall survival (median 123 months), followed by single patients (median 111 months), divorced (median 102 months), separated (median 60 months), and widowed (median 43 months). Bladder cancer-specific survival followed relatively similar trends with married patients having significantly better survival when compared to other groups. When we adjusted for age, sex, race, stage, grade, and undergoing cancer-targeted surgery, married patients had better survival outcomes when compared to single patients (HR = 1.322, p-value < 0.001), separated patients (HR = 1.409, p-value < 0.001), divorced patients (HR = 1.358, p-value < 0.001), and widowed patients (HR = 1.242, p-value < 0.001). Conclusions: Our results demonstrate a clear survival advantage in cases of transitional cell carcinoma of the bladder with married individuals having the highest overall and cancer-specific median survival. These results shed the light on the lifestyle and the psychosocial factors, including the social support that married patients may have comparing to unmarried patients, and their effect on the disease prognosis and survival. Understanding the social and psychological factors associated with the observed disparity may help enhance management plans for affected patients.

A multicenter retrospective study to evaluate real-world clinical outcomes in patients with metastatic renal cell carcinoma (mRCC) and brain metastasis treated with ipilimumab and nivolumab

637

Background: The combination of ipilimumab & nivolumab (I+N) followed by maintenance nivolumab has improved outcomes in patients (pts) with mRCC. Little is known about the outcomes in mRCC pts with brain metastasis. In this multicenter retrospective analysis, we present a real-world experience in pts with brain metastasis treated with I+N. Methods: Pts with mRCC and brain metastases treated with I+N at the Duke Cancer Institute and Cleveland Clinic were identified. Pt characteristics were summarized with descriptive statistics. Fisher’s exact test was used to determine predictors of response (alpha 0.05). Results: From 10/2017 to 2/2019, 17 pts received I+N for mRCC with brain metastases. Median age was 60; 29% were female. IMDC risk was 18%/59%/24% favorable/intermediate/poor, and 77% were clear cell histology. Pts received I+N as either first-line (65%) or ≥ second-line (35%) therapy. Of the pts evaluable for response: objective response rate (ORR) was 42% [0% CR]; with 29% achieving stable disease and 18% progressive disease as their best response. Median duration on therapy was 13 weeks. 59% of pts developed an immune-related adverse event (AE). The most common reason for treatment discontinuation was disease progression (47%) followed by AEs (18%). There were no significant predictors of any radiographic response category (PR, SD, or PD) among variables assessed (gender, IMDC risk, histology, presence of bone metastasis, line of therapy, or presence of irAE). Of note, 50% (3/6) patients treated in the second-line or greater setting experienced a PR. Conclusions: In our real-world cohort of mRCC patients with brain metastasis, I+N is clinically effective. Further investigation is warranted in this population given exclusion from prior clinical trials.

Clinical activity of ipilimumab plus nivolumab (Ipi/Nivo) in patients (pts) with metastatic non-clear cell renal cell carcinoma (nccRCC)

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Background: Ipi/Nivo is a standard of care for pts with metastatic clear cell RCC. The clinical activity of Ipi/Nivo in patients with metastatic nccRCC remains poorly defined. Methods: Metastatic nccRCC pts who were treated with Ipi/Nivo at Cleveland Clinic or UT Southwestern were retrospectively reviewed. Ipi/Nivo was administered as per CHECKMATE 214. Computed tomography imaging was obtained at baseline and every 12 weeks to assess disease response per RECIST 1.1 criteria. Baseline pt characteristics, outcome to therapy and adverse effects as per CTCAE v5.0 were collected. Results: Eighteen pts with metastatic nccRCC histology who were treated with Ipi/Nivo were identified. The median age was 60 years (range, 32-81). Non clear cell histologies included adenocarcinoma of renal origin not otherwise specified (2), unclassified (3), papillary (6), chromophobe (5), translocation (1) and medullary histology (1). ECOG PS was 0 (7 pts); 1 (9 pts) and 2 (2 pts). Fourteen patients were male and four female. IMDC risk group at the time of initiation of Ipi/Nivo was favorable (2 pts), intermediate (14 pts) and poor (2 pt). Fourteen pts received Ipi/ Nivo as first line treatment, two pts received Ipi/Nivo after prior TKI and two pts received Ipi/ Nivo as third line treatment after prior chemotherapy and nivolumab monotherapy. In total, fourteen pts had restaging scans with four pts demonstrating partial response (PR 28%), two with stable disease (SD 14%) and eight with progressive disease (PD 58%). Four pts died (22%) – three from the disease and one from treatment related complication (encephalitis).Four pts experienced diarrhea- three pts (grade 2) and one pt ( grade 3) , three developed hepatotoxicity- one pt (grade 2) and two pts (grade 3), one pt each developed hypophysitis (grade 3), fatigue (grade 2) , rash (grade 2) and encephalitis (grade 3). All 100% pts required steroids, one each got infliximab and Mycophenolate Mofetil. . All 100% pts required steroids, one each got infliximab and Mycophenolate Mofetil. Conclusions: Ipi/Nivo is feasible and safe in patients with metastatic nccRCC with preliminary evidence of anti-tumor activity

Association of cell-free DNA (cfDNA) levels with myeloid-derived suppressor cells (MDSC) levels in blood of patients (pts) with muscle invasive (MI) and metastatic (met) bladder cancer (BC)

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Background: cfDNA can be detected in healthy individuals but higher concentrations are present in pts with cancer. MDSC are immature immunosuppressive cells that can be mobilized from bone marrow by tumor-related factors. Higher blood MDSC levels have been associated with worse outcomes in pts with solid tumors including BC. We assessed correlations between cfDNA and MDSC levels in pts with MIBC and met BC. Methods: Peripheral blood from pts with MIBC and met BC was collected in Streck BCT tubes and processed to obtain cf nucleic acid extracts. Total cfDNA was determined by fluorimetry. Cell-free DNA fragment size was measured by Bioanalyzer DNA analysis; 100-400 bp fragments (mono- and di-nucleosomal fragments linked to granulocytic processing of apoptotic and necrotic tumor cells) were designated low molecular weight (LMW-frags). The % of MDSC (CD33+/HLADR-) and subtypes were measured. MDSC subtypes were defined as polymorphonuclear (PMN-MDSC: CD15+/CD14-), monocytic (M-MDSC: CD15-/CD14+) and uncommitted (UNC-MDSC: CD15-/CD14-). Spearman’s correlation test was used for analysis. Results: Blood from 37 pts (19% women, 40% never smokers) with MIBC or met BC was collected: 15 (41%) with MIBC and 22 (59%) with met BC at time of collection. There was a significantly positive correlation between total MDSC and cfDNA levels (r = 0.57, P = 0.0003). Among MDSC subtypes, there was a significantly positive correlation between PMN-MDSC and cfDNA levels (r = 0.61, P < 0.0001). The higher level of LMW-frags was significantly but moderately associated with higher total MDSC (r = 0.43, P 0.008) and PMN-MDSC (r = 0.41, P 0.01) levels. There was no significant correlation between cfDNA level and other MDSC subtypes. Conclusions: There was a positive correlation between total and PMN-MDSC with cfDNA levels in blood from pts with MIBC and met BC. That may suggest a putative role for MDSC in mediating cfDNA release into the circulation, consistent with prior reports of granulocyte-mediated ctDNA processing. Further studies need to identify mechanisms and implications of our findings and potential correlation with clinical outcomes.

First-line PD(L)1 inhibitors for platinum-ineligible advanced urothelial carcinoma (aUC)

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Background: FDA modified the label for 1st-line pembrolizumab or atezolizumab to PD-L1 high cisplatin-ineligible or platinum-ineligible aUC patients (pts) regardless of PD-L1 expression. However, the outcomes when using PD-(L)1 inhibitors for platinum-ineligible pts are unclear. We hypothesized that treatment response and outcomes are comparable to data reported in trials in the 1st line setting of aUC, and conducted a retrospective study to test this hypothesis using data outside the clinical trial setting. Methods: We collected data from 8 institutions for aUC pts with locally advanced unresectable or metastatic UC. The following criteria were used to define pts platinum-ineligible while comorbidities, age and physician discretion were also allowed: Cr Cl < 30 ml/min, ECOG PS 3, Cr Cl 30-59 ml/min and ECOG PS 2. Demographic & clinical variables and outcomes (overall response rate [ORR], overall survival [OS]) were collected. A Cox regression analysis was used to explore associations of baseline variables with response and outcomes. Results: Data were available for 79 pts. Pts received atezolizumab [n = 41], pembrolizumab [n = 28], nivolumab [n = 7] or durvalumab [n = 3]. Median age was 74 years (45-93). Reasons for platinum-ineligibility were: Cr Cl < 30 ml/min (n = 26), ECOG PS 3 (n = 8), ECOG-PS 2 and Cr Cl < 30-59ml/min (n = 14), elderly/co-morbidities (n = 17), and ‘unavailable’ (n = 14). Median OS was 45 weeks (CI 32-80) and ORR was 27.9%: Complete response in 4 pts [5.1%], partial response in 18 pts [22.8%], stable disease in 19 pts [24.1%], progressive disease in 34 pts [43 %]; data for 4 pts [5.1%] was unavailable for best response. Toxicity of any grade and Grade ≥3 was seen in 41.8% and 31.7% of pts, respectively. Hemoglobin (HR = 0.78, 95% CI 0.68 - 0.90, P = 0.001) and liver metastasis (HR = 1.13, 95% CI 0.51 - 2.53, P = 0.036) correlated with OS. Conclusions: The efficacy and toxicities of 1st-line PD-(L)1 inhibitors for platinum-ineligible pts outside clinical trials appear comparable to those reported in trials for unselected cisplatin-ineligible pts. Further validation is required including data based on PD-L1 status and other biomarkers. Platinum-ineligible pts with aUC warrant evaluation of novel safe and effective agents.

Implications of the United States Preventive Services Task Force (USPSTF) recommendations on prostate cancer (PCa) stage migration

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Background: Prostate specific antigen (PSA) screening has been controversial, given unrefined screening guidelines leading to overdiagnosis and overtreatment of “indolent” PCa. In 2008, the USPSTF recommended against PSA screening for men aged ≥75 and in 2012 broadened this recommendation to include all men. The impact of these changes is unstudied. We hypothesize that these screening changes could delay the diagnosis of advanced PCa. Methods: The Surveillance, Epidemiology and End Results Program (SEER) was used to identify men (age 55-69) diagnosed with PCa between 2004-2015. PCa stage was categorized as nodal (N1M0) and metastatic (NxM1). Trend analysis was stratified based on year 2004-2008 (group 1), 2009-2012 (group 2), and 2012-2015 (group 3). Using group 2 as a reference, multivariable logistic regression was used to identify predictors for N1M0 and NxM1 in each group. Results: From 2004-2015, there were 603,323 eligible men diagnosed with PCa (group 1: 262,240 men, group 2: 210,045 men, group 3: 131,038 men). In group 1, 1.4% had N1M0 and 2.8% had NxM1. In group 2, 1.6% had N1M0 and 3.7% had NxM1. In group 3, 1.4% had N1M0, and 6.1% had NxM1. The adjusted odds ratio (AOR) of N1M0 was 0.78 (95%CI 0.74-0.82; p<0.0001) in group 1 and 1.71 (95%CI 1.63-1.80; p<0.0001) in group 3. Similar AOR trends were seen in NxM1 (group 1, 0.71; 95%CI 0.68-0.73, p< 0.0001 vs. group 3, 1.70; 95% CI 1.63-1.75, p<0.0001). (Table) Subset analysis of non-eligible patients (age >70 and <55) showed a similar stage migration. Conclusions: With each USPSTF recommendation, there have been significantly more diagnoses of advanced PCa; suggesting stage migration. The sequelae of having advanced PCa include more aggressive treatments, increased financial burden, and reduced quality of life. Future population studies are warranted to investigate whether the updated 2018 USPSTF recommendation now encapsulates the best target population.[Table: see text]

Circulating cell-free DNA (cfDNA) levels and fragmentation pattern can distinguish nonmuscle invasive (NMI) from muscle-invasive (MI) and metastatic (met) bladder cancer (BC)

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Background: Occult MI and met BC may be under-staged. Circulating cfDNA may be a dynamic, low-cost and minimally invasive biomarker. We evaluated correlations between total circulating cfDNA and presence of MIBC and met BC. We hypothesized that the relative abundance of circulating low molecular weight cfDNA would correlate with BC stage. Methods: Peripheral blood from pts with BC was collected in Streck BCT tubes and processed to obtain cf nucleic acid extracts. Total cfDNA quantity (ng/ml) was assessed by fluorimetry. cfDNA fragment size was measured by Bioanalyzer DNA analysis. Wilcoxon rank sum test and Fisher’s Exact test were used to compare cfDNA quantity and fragmentation pattern among pts with NMIBC, MIBC, met BC. Results: Blood was obtained from 58 pts with BC (20% women, 34% never smokers, median age 71 (29-89). There was no significant difference in cfDNA between MIBC and met BC, however, it was significantly lower in pts with NMIBC vs MIBC and met BC (table). The concentration of low molecular weight fragments (LMW-frags) (100 - 400) base pairs and the ratio of LMW-Frag to cfDNA were significantly different between pts with NMIBC and pts with MIBC or met BC (table). Using median values as the cutoff, there was a significantly higher proportion of pts with cfDNA > 7 ng/ml and LMW-frags > 1.6 ng/mL, in MIBC & met BC vs NMIBC (p < 0.001). The % of pts with LMW-frags to cfDNA > 30%, was significantly different among NMIBC, MIBC and met BC groups: 16%, 53%, 78%, respectively (p < 0.001). Conclusions: This exploratory study suggests that cfDNA levels may correlate with BC stage. Measuring the relative abundance of LMW-frags with the expected size of cf DNA can enhance the specificity of cfDNA analysis for distinction between MIBC and met BC. Further studies are needed to confirm findings and define the optimal cut-points for optimal BC staging. [Table: see text]

Blood myeloid derived suppressor cells (MDSC) in metastatic urothelial carcinoma (mUC) are correlated with neutrophil-to-lymphocyte ratio (NLR) and overall survival (OS)

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Background: MDSC have been linked to the chronic inflammatory microenvironment of tumor cells and pathologic outcomes in UC patients (pts) undergoing cystectomy. NLR is an established inflammatory biomarker with prognostic properties in mUC. We hypothesized that MDSCs correlate with NLR and OS in mUC. Methods: MDSCs were measured in blood samples from mUC patients by fresh unfractionated whole blood (WB) and peripheral blood mononuclear cells (PBMC). MDSCs were identified by flow cytometry in WB and defined as LinloCD33+/HLADR- (Total MDSC). MDSC subsets were defined as polymorphonuclear (PMN-MDSC: CD15+/CD14-), monocytic (M-MDSC: CD15-/CD14+), and uncommitted (UC-MDSC: CD15-/CD14-). MDSC populations were presented as % of live nucleated blood cells from PB and absolute numbers from WB. Spearman’s correlation assessed correlations between MDSC & NLR. Kaplan Meier curves and log rank test estimated OS from the time of MDSC collection to last follow up or date of death. Results: Of 79 pts, 77% were men and 42% were never smokers with a median age of 69 (31-83). Overall, 71% had pure UC and 81% had lower tract UC. Prior therapies include intravesical therapy (22%), neoadjuvant chemotherapy (31%), and cystectomy/nephroureterectomy (61%). Median follow up was 12 months (range: 0.6-36.5). PMN-MDSC was the predominant subset in WB and PBMC. There was significant correlation between individual MDSC subsets in WB and PBMC (p≤0.001). Negative correlation was noted between NLR and WB UC-MDSC:PMN-MDSC ratios (rho = -0.27, p = 0.03), as well as NLR and PB UC-MDSC:PMN-MDSC (rho = -0.28, p = 0.02). Median survival was 17.7 months (95% CI: 11.0-NA months). Overall 1-yr and 3-yr survival were 0.60 (95% CI: 0.49-0.73) and 0.15 (95% CI: 0.03-0.67), respectively. Higher WB UC-MDSC levels were associated with shorter OS (HR 2.85, 95% CI: 1.43-5.65, p = 0.003). Conclusions: Specific MDSC subsets correlate with NLR. Higher WB UC-MDSC levels have negative prognostic roles for OS. Given the feasibility of serial blood draws, dynamic assessment of MDSC over time and further validation with longer follow up are needed.

Moderately hypofractionated radiotherapy for localized prostate cancer: Long-term outcomes for 854 consecutive patients treated over 10 years (70 Gy in 2.5 Gy/fraction)

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Background: Moderately hypofractionated radiotherapy has been increasingly adopted in the management of localized prostate cancer (PCa). We report 10-year outcomes for patients treated with intensity modulation radiation therapy (IMRT) for localized PCa with 70 Gy in 28 fractions at 2.5 Gy/fraction. Methods: This retrospective study included 854 consecutive patients with localized PCa treated with image-guided moderately hypofractionated IMRT at a single institution between 1998 and 2012. Patients with a single intermediate-risk factor were considered to have favorable intermediate-risk (FIR) disease; multiple intermediate-risk factors were considered unfavorable (UIR). Biochemical relapse free survival (bRFS), clinical relapse free survival (cRFS), overall survival (OS) and PCa specific mortality (PCSM) were analyzed used Kaplan-Meier analysis. Grade ≥3 genitourinary (GU) and gastrointestinal (GI) toxicities were recorded (CTCAE v4.03). Results: The median follow-up was 11.3 years (Max. 19 years). For patients with low-risk (LR, 31%), FIR (28%), UIR (12.5%), and high-risk (HR, 28.5%) disease the 10 year bRFS rates were 88%, 78%, 71% and 42%, respectively (p < 0.0001). The number of patients receiving no ADT, 1-6 months, or > 6 months of ADT were 39%, 50%, and 11%, respectively, reflecting practice patterns during this treatment period. The 10-year cRFS were 95%, 91%, 85% and 72% for patients with LR, FIR, UIR, and HR, respectively (p < 0.0001). The 10-year actuarial OS rate was 69% (95% CI 66-73%) and the 10-year PCSM was 6.8% (95% CI 5.1-8.6%) overall. For patients with LR, FIR, UIR and HR disease, the 10 year PCSM rates were 2%, 5%, 5% and 15%. 10-year cumulative incidence of grade ≥3 GU and GI toxicity was 2% and 1%, respectively. Multivariate analysis identified associations between clinical variables (ADT use, PSA nadir < 0.5ng/ml, and ISUP Grade Group) and bRFS, cRFS, and PCSM. Conclusions: Moderately hypofractionated IMRT with daily image guidance for localized PCa demonstrates favorable 10-year oncologic outcomes with a low incidence of toxicity for patients across all risk groups.

Clinical activity of ipilimumab plus nivolumab (Ipi/Nivo) in patients (pts) with metastatic non-clear cell renal cell carcinoma (nccRCC)

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Background: Ipi/Nivo is a standard of care for pts with metastatic clear cell RCC. The clinical activity of Ipi/Nivo in patients with metastatic nccRCC remains poorly defined. Methods: Metastatic nccRCC pts who were treated with Ipi/Nivo at Cleveland Clinic or UT Southwestern were retrospectively reviewed. Ipi/Nivo was administered as per CHECKMATE 214. Computed tomography imaging was obtained at baseline and every12 weeks to assess disease response per RECIST 1.1 criteria. Baseline pt characteristics, outcome to therapy and adverse effects as per CTCAE v5.0 were collected. Results: Thirteen pts with metastatic nccRCC histology who were treated with Ipi/Nivo were identified. The median age was 60 years (range, 32-81). Non clear cell histologies included adenocarcinoma of renal origin not otherwise specified (2), unclassified (3), papillary (3), chromophobe (3), translocation (1) and medullary histology (1). Nine pts had ECOG PS 0; four pts had ECOG PS 1. Eleven patients were male and two female. IMDC risk group at time of initiation of Ipi/Nivo was favorable (2 pt), intermediate (10 pts) and poor (1 pt). Nine pts received Ipi/ Nivo as first line treatment, three pts received Ipi/Nivo after prior TKI and one pt received Ipi/ Nivo as third line treatment after prior chemotherapy and nivolumab monotherapy. In total, eight pts have thus far undergone restaging scans with three pts demonstrating partial response (PR), one pt demonstrating stable disease (SD) and four pts demonstrating progressive disease (PD). Two pts experienced grade 2 diarrhea, one after 4 cycles and another after 3 cycles of Ipi/Nivo and required prednisone. One pt demonstrated grade 3 hepatotoxicity after 2 cycles of Ipi/Nivo and required prednisone and Mycophenolate Mofetil while another pt demonstrated grade 1 hepatotoxicity after 3 cycles of Ipi/ Nivo requiring prednisone. One pt experienced grade 2 pancreatitis requiring steroids after one dose of Ipi/Nivo. One pt experienced grade 2 fatigue after 1 cycle of Ipi/Nivo requiring prednisone. Conclusions: Ipi/Nivo is feasible and safe in patients with metastatic nccRCC with preliminary evidence of anti-tumor activity. Updated clinical data will be presented.

First-line PD1/PD-L1 inhibitors for platinum-ineligible advanced urothelial carcinoma (UC)

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Background: FDA modified the label for the use of 1st-line pembrolizumab or atezolizumab therapy to PD-L1 high cisplatin-ineligible or platinum-ineligible UC patients (pts) regardless of PD-L1 expression. However, the outcomes when using PD1/PD-L1 inhibitors for platinum-ineligible pts are unclear. We conducted a retrospective study to evaluate clinical outcomes with first-line PD1/PD-L1 inhibitors for platinum-ineligible pts with advanced UC in a real-world setting. Methods: We collected data retrospectively from 6 institutions. The following criteria were deemed to render pts platinum-ineligible although physician discretion was also allowed: Cr Cl < 30 ml/min, ECOG-PS 3, Both Cr Cl 30 to < 60 AND ECOG-PS 2. Demographic and clinical variables and outcomes (overall response rate [ORR], overall survival [OS]) were collected. A Cox regression analysis was done to study the association of baseline variables with response and survival. Results: Data were available for 45 pts. Pts received atezolizumab [n = 24], pembrolizumab [n = 11], nivolumab [n = 7] and durvalumab [n = 3]. The mean age was 72.2 (range 45-90) years. The reasons for platinum-ineligibility were: Cr Cl < 30 ml/min (n = 17), ECOG-PS 3 (n = 3), ECOG-PS 2 plus Cr Cl < 60 ml/min (n = 7), elderly with co-morbidities (n = 12), and reason was unavailable for 6 pts. The median OS was 37 weeks (CI 30-80). ORR was 27.3%: Complete response in 3 pts [6.8%], partial response in 9 pts [20.5%], stable disease in 11 pts [25%] and progressive disease in 21 pts [47.7%] and data for 1 patient was unavailable. Toxicity of any grade were seen in 42.2% of pts and Grade ≥3 toxicity in 9 pts’ [20%]. There were no treatment-related deaths. Anemia (HR = 0.75, 95% CI 0.62 - 0.92, P = 0.005) and liver metastasis (HR = 1.17, 95% CI 0.47 - 2.93, P = 0.017) correlated with shorter OS. Conclusions: To our knowledge, this is the 1st report of efficacy and toxicity of PD1/PD-L1 inhibitors as1st-line therapy for platinum ineligible UC. Data appear comparable to those reported previously in unselected cisplatin-ineligible pts receiving pembrolizumab or atezolizumab in phase II trials. Validation is needed in larger datasets and prospective trials.

Neoadjuvant durvalumab +/- tremelimumab affects the expression of immune checkpoint (IC) molecules on myeloid derived suppressor cells (MDSC) in patients (pts) with locally advanced renal cell carcinoma (RCC)

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Background: In a single arm, open label phase 1b clinical trial the safety of neoadjuvant durvalumab +/- tremelimumab was studied in pts with (w) locally advanced RCC. Expression of IC molecules on immunomodulatory cells in peripheral blood (PB) and tumor (T) and the association w treatment (tx) was investigated. Methods: Pts with ≥ T2bN0-1M0 RCC received either durvalumab or combination durvalumab + tremelimumab prior to surgery. Blood samples were drawn prior to neoadjuvant tx, prior to surgery, and approximately 30 days after surgery before adjuvant tx. The percentage of MDSC (CD33+/HLADR-) and subtypes in PB and T and expression of PD1, PD-L1, and V-domain Ig suppressor of T cell activation (VISTA) were measured. MDSC subtypes included polymorphonuclear (PMN; CD15+/CD14-), monocytic (M; CD15-/CD14+) and uncommitted (UC; CD15-/CD14-). Linear mixed model was used for each MDSC subtype to estimate and compare cohorts over time. Results: Eighteen pts were enrolled: 4 women and 14 men, median age 62, 17 pts had T3-4 and 4 pts had N1 disease. Six pts received 1 dose of durvalumab and 12 pts received 1 dose of durvalumab + tremelimumab before surgery. Tx-related grade 3 adverse events (per CTCAE, v5.0) included thrombocytopenia, bilateral lower extremity weakness, hyperglycemia, chest pain, and diabetic ketoacidosis.One pt had grade 4 elevated lipase. One pt had sudden death from a non-drug related cardiac event 9 days after receiving combination therapy prior to surgery. PB and T samples from 17 pts were available. Expression of VISTA on M-MDSC and UC-MDSC were positively correlated in PB and T (Spearman’s rho = 0.61; P=0.03 for both). VISTA expression on UC-MDSC in PB was significantly higher in pts who received durvalumab monotherapy compared to those treated w durvalumab + tremelimumab (P=0.04). Frequencies of PD-L1 expression on M-MDSC and UC-MDSC in PB decreased significantly from pre- to post-neoadjuvant tx (P < 0.01). Conclusions: Neoadjuvant durvalumab + tremelimumab in pts w locally advanced RCC is feasible and affects the expression of IC molecules (PD-L1 and VISTA) on M-MDSC and UC-MDSC. Clinical trial information: NCT02762006.