Racial Differences in Cutaneous Events Among Patients Receiving Enfortumab Vedotin

INTRODUCTION

Enfortumab vedotin (EV) is an antibody-drug conjugate approved alone and in combination with pembrolizumab for advanced urothelial cancer (UC). EV-related-cutaneous-events (EVCEs) are common and rarely life-threatening. Black patients are frequently under-represented in oncology trials, and dermatologic conditions may vary with race.

METHODS

Therefore, this retrospective analysis investigated differences in EVCE frequency between Black and White patients in an urban cohort (Johns Hopkins [JH]) and a US-based, nationwide electronic health record (EHR)-derived deidentified database (Flatiron Health [FH]) with sub-group analysis of those who had received prior pembrolizumab.

RESULTS

The study included 12 Black patients in the JH Cohort (17.1%) and 24 Black patients in the FH Cohort (7.6%). In both cohorts, the frequency of EVCEs among Black patients was higher compared to White patients (JH: 66.7% vs. 33.3%; FH: 25.0% vs. 15.8%), though not statistically significant. In the larger FH Cohort EVCEs were significantly more common among Black compared to White patients treated with prior pembrolizumab (Odds Ratio [OR]: 4.76 [95%CI: 1.42, 15.95]) and recent pembrolizumab (within 90 days of EV initiation) (OR 9.00 [95%CI: 1.94, 41.66]).

CONCLUSION

This hypothesis-generating retrospective study, comprising the largest population of EV-treated Black patients reported to date, emphasizes the importance of attentiveness to EVCEs among Black patients, particularly with receipt of pembrolizumab.

The JAVELIN Bladder Medley trial: avelumab-based combinations as first-line maintenance in advanced urothelial carcinoma

Results from JAVELIN Bladder 100 established avelumab (anti-PD-L1) first-line maintenance as the standard-of-care treatment for patients with advanced urothelial carcinoma (UC) that has not progressed with first-line platinum-based chemotherapy. We describe the design of JAVELIN Bladder Medley (NCT05327530), an ongoing phase II, multicenter, randomized, open-label, parallel-arm, umbrella trial. Overall, 252 patients with advanced UC who are progression-free following first-line platinum-based chemotherapy will be randomized 1:2:2:2 to receive maintenance therapy with avelumab alone (control group) or combined with sacituzumab govitecan (anti-Trop-2/topoisomerase inhibitor conjugate), M6223 (anti-TIGIT) or NKTR-255 (recombinant human IL-15). Primary end points are progression-free survival per investigator and safety/tolerability of the combination regimens. Secondary end points include overall survival, objective response and duration of response per investigator, and pharmacokinetics.

PrECOG PrE0807: A Phase 1b Feasibility Trial of Neoadjuvant Nivolumab Without and with Lirilumab in Patients with Muscle-invasive Bladder Cancer Ineligible for or Refusing Cisplatin-based Neoadjuvant Chemotherapy

BACKGROUND AND OBJECTIVE

Neoadjuvant cisplatin-based chemotherapy prior to radical cystectomy (RC) improves overall survival (OS) in muscle-invasive bladder cancer (MIBC). However, many patients are cisplatin ineligible; therefore, new treatment options are needed. Nivolumab without/with lirilumab prior to RC was investigated in cisplatin-ineligible patients in this phase 1b trial (NCT03532451) to determine its safety/feasibility.

METHODS

Patients with localized MIBC received two doses of nivolumab (480 mg) alone (cohort 1) or with lirilumab (240 mg; cohort 2) prior to RC. Cohorts were enrolled sequentially. The key eligibility criteria were cT2-4aN0-1M0 stage and cisplatin ineligibility/refusal. The primary endpoint was the rate of grade (G) ≥3 treatment-related adverse events (TRAEs) as per Common Terminology Criteria for Adverse Events version 5.0. The key secondary endpoints included the proportion of patients who underwent RC >6 wk after the last dose, CD8+ T-cell density change between pretreatment transurethral resection of bladder tumor (TURBT) and post-treatment RC, ypT0N0,

KEY FINDINGS AND LIMITATIONS

Among 43 patients enrolled (n = 13, cohort 1; n = 30, cohort 2), 13 and 29 completed intended neoadjuvant therapy, respectively, in cohorts 1 and 2, and 41 underwent RC. The median time from the last dose to RC was 4 wk. The G3 TRAEs occurred in 0% (90% confidence interval [CI] 0-21%) of patients in cohort 1 and 7% (90% CI 1-20%) in cohort 2; all these TRAEs resolved and no G4/5 TRAEs occurred. No patient had delayed RC for >6 wk. In cohorts 1 and 2, ypT0N0 rates for patients with MIBC and RC were 17% and 21%,

CONCLUSIONS AND CLINICAL IMPLICATIONS

Neoadjuvant nivolumab-based immunotherapy was safe, feasible, and well tolerated in cisplatin-ineligible patients with MIBC. Although ypT0N0 rates were lower than expected, 2-yr survival rates seem to be comparable with those of other neoadjuvant immunotherapy trials. Nivolumab is being evaluated in the CA-017-078 trial (NCT03661320).

PATIENT SUMMARY

For patients with muscle-invasive bladder cancer unable to receive cisplatin-based chemotherapy, treatment with nivolumab without and with lirilumab prior to radical cystectomy was safe, feasible, and well tolerated. Nivolumab-based immunotherapy showed lower pathologic response rates than but similar survival rates to other neoadjuvant immunotherapy trials.

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Key Words

• Anti-KIR antibody
• Bladder cancer
• Immune checkpoint inhibitors
• Neoadjuvant therapy
• Urothelial carcinoma

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Affiliation(s)

Petros Grivas Fred Hutchinson Cancer Center, University of Washington, Seattle, WA, USA.
Vadim S Koshkin Helen Diller Family Cancer Center, University of California San Francisco, San Francisco, CA, USA
Xiangying Chu Dana-Farber Cancer Institute, Boston, MA, USA
Suzanne Cole University of Texas Southwestern Medical Center, Dallas, TX, USA
Rohit K Jain H Lee Moffitt Cancer Center, Tampa, FL, USA
Robert Dreicer University of Virginia Cancer Center, Charlottesville, VA, USA
Jeremy P Cetnar Oregon Health and Science University, Portland, OR, USA
Debasish Sundi Department of Urology, The Ohio State University Wexner Medical Center, Columbus, OH, USA
Benjamin A Gartrell Montefiore Medical Center/Albert Einstein College of Medicine, Bronx, NY, USA
Matthew D Galsky Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
Brianna Woo Fred Hutchinson Cancer Center, University of Washington, Seattle, WA, USA
Elsa Li-Ning-Tapia University of Texas MD Anderson Cancer Center, Houston, TX, USA
Noah M Hahn Department of Oncology, Johns Hopkins School of Medicine, Baltimore, MD, USA; Department of Urology, Johns Hopkins School of Medicine, Baltimore, MD, USA
Michael A Carducci Sidney Kimmel Cancer Center, Johns Hopkins School of Medicine, Baltimore, MD, USA

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Clinicopathologic and Survival After Cystectomy Outcomes in Squamous Cell Carcinoma of the Bladder

BACKGROUND

Squamous cell carcinoma of the bladder (SqCC) is a rare disease with limited management data. Thus, we sought to characterize the clinicopathologic and survival outcomes amongst patients with SqCC and explore the association of squamous differentiation within urothelial carcinoma (UC w/Squam), as compared to muscle invasive pure UC.

METHODS

We conducted a single-center retrospective cohort study of patients, stratified by histology, who underwent cystectomy for MIBC. Baseline clinicopathologic characteristics were compared, and overall survival was assessed using Kaplan-Meier method.

RESULTS

We identified 1,034 patients; 37 (3.58%) with SqCC histology, 908 (87.81%) with UC histology, and 89 (8.61%) with UC w/ Squam histology. Among SqCC patients, a higher proportion were Black and similarly a higher proportion were women; amongst patients with UC w/ Squam a higher proportion had lower BMI; and amongst patients with UC a higher proportion had lower clinical (c) T, cN, pathological (p) T, and pN stages. Patients presenting with UC were more likely to receive intravesical therapy; patients presenting with SqCC were less likely to receive neoadjuvant chemotherapy (NAC). Adjuvant chemotherapy rates were similar. With post-hoc Bonferroni analysis, overall survival, cancer-specific survival, and recurrence-free survival were significantly worse for the UC w/ Squam cohort.

CONCLUSIONS

UC w/ Squam histology was associated with worse survival outcomes after cystectomy for muscle invasive bladder cancer compared to UC. Our results suggest that UC w/ Squam is associated with more advanced disease compared to UC, warranting further prospective work on consideration of combination therapies for patients with this disease state.

Checkpoint Inhibitors in Urothelial Carcinoma-Future Directions and Biomarker Selection

CONTEXT

Several recent phase 2 and 3 trials have evaluated the efficacy and toxicity of checkpoint inhibitor (CPI) therapy for urothelial carcinoma (UC) in the metastatic, localized muscle-invasive UC (MIUC), upper tract UC, and non-muscle-invasive bladder cancer (NMIBC) disease state.

OBJECTIVE

To assess the outcomes and toxicity of CPIs across the treatment landscape of UC and contextualize their application to current real-world treatment.

EVIDENCE ACQUISITION

We queried PubMed, Web of Science, and EMBASE databases and conference abstracts to identify prospective trials examining CPIs in UC. The primary endpoints included overall survival, recurrence-free survival, and toxicity (when available). A secondary analysis included biomarker evaluation of response.

EVIDENCE SYNTHESIS

We identified 21 trials, 12 phase 2 and nine phase 3 trials, in which a CPI was used for metastatic UC (seven), MIUC (nine), and NMIBC (five). For first-line (1L) metastatic UC, concurrent chemotherapy with CPIs failed to show superiority. Improved overall and progression-free survival for switch maintenance avelumab (after achieving stable disease or response with induction systemic chemotherapy) has established the current standard of care for 1L metastatic UC. A single-agent CPI is a consideration for patients unable to tolerate chemotherapy. CPIs in the perioperative setting are limited to only the adjuvant treatment with nivolumab after radical surgery for MIUC in patients at a higher risk of recurrence based on pathologic stage. Only pembrolizumab is approved by the Food and Drug Administration for carcinoma in situ unresponsive to bacillus Calmette-Guérin (BCG) in patients who are not fit for or who refuse radical cystectomy. Trials investigating CPIs in combination with multiple immune regulators, antibody drug conjugates, targeted therapies, antiangiogenic agents, chemotherapy, and radiotherapy are enrolling patients and may shape the future treatment of patients with UC.

CONCLUSIONS

CPIs have an established role across multiple states of UC, with broadened applications likely to occur in the future. Several combinations are being evaluated, while the development of predictive biomarkers and their validation may help identify patients who are most likely to respond.

PATIENT SUMMARY

Our findings highlight the broad activity of checkpoint inhibitors in urothelial carcinoma, noting the need for further investigation for the best application of combinations and patient selection to patient care.

Antitumor immunity as the basis for durable disease-free treatment-free survival in patients with metastatic urothelial cancer

Cisplatin-based chemotherapy has been associated with durable disease control in a small subset of patients with metastatic urothelial cancer. However, the mechanistic basis for this phenomenon has remained elusive. Antitumor immunity may underlie these exceptional responders. In a phase II trial evaluating a phased schedule of gemcitabine and cisplatin followed by gemcitabine and cisplatin with ipilimumab for metastatic urothelial cancer, 4 of 36 patients achieved durable disease-free treatment-free survival (DDFTFS) and remain in remission over 5 years after enrolment on the study. We sought to identify the genomic and immunological mechanisms associated with functional cures of such patients. Whole exome sequencing was performed on pretreatment archival tumor tissue. Neoantigen prediction and ranking were performed using a novel pipeline. For a subset of patients with available biospecimens, selected peptides were tested for neoantigen-specific T cell reactivity in peripheral blood CD4+ and CD8+ T cells cultured with autologous antigen-presenting cells at baseline, postchemotherapy, and postchemotherapy and ipilimumab timepoints. Multiplex assays of serum protein analytes were also assessed at each time point. Serum proteomic analysis revealed that pretreatment, patients achieving DDFTFS demonstrated an immune activated phenotype with elevations in TH1 adaptive immunity, costimulatory molecules, and immune checkpoint markers. After combination cisplatin-based chemotherapy and ipilimumab treatment, DDFTFS patients again displayed enrichment for markers of adaptive immunity, as well as T cell cytotoxicity. CD27 was uniquely enriched in DDFTFS patients at all timepoints. Neoantigen reactivity was not detected in any patient at baseline or post two cycles of chemotherapy. Both CD4+ and CD8+ neoantigen-specific T cell reactivity was detected in two of two DDFTFS patients in comparison to zero of five non-DDFTFS patients after combination cisplatin-based chemotherapy and ipilimumab treatment. Antitumor immunity may underlie functional cures achieved in patients with metastatic urothelial cancer treated with cisplatin-based chemotherapy and immune checkpoint blockade. Probing the mechanistic basis for DDFTFS may facilitate the identification of biomarkers, therapeutic components, and optimal treatment sequences necessary to extend this ultimate goal to a larger subset of patients.

A Phase 1b/2 Study of Atezolizumab with or Without Bacille Calmette-Guérin in Patients with High-risk Non-muscle-invasive Bladder Cancer

BACKGROUND

Bacille Calmette-Guérin (BCG) is the standard therapy after transurethral resection of bladder tumour for high-risk non-muscle-invasive bladder cancer (NMIBC). However, post-BCG recurrence/progression occurs frequently, and noncystectomy options are limited.

OBJECTIVE

To evaluate the safety and clinical activity of atezolizumab ± BCG in high-risk BCG-unresponsive NMIBC.

DESIGN, SETTING, AND PARTICIPANTS

This phase 1b/2 GU-123 study (NCT02792192) treated patients with BCG-unresponsive NMIBC who had carcinoma in situ with atezolizumab ± BCG.

INTERVENTION

Patients in cohorts 1A and 1B received atezolizumab 1200 mg IV q3w for ≤96 wk. Those in cohort 1B also received standard BCG induction (six weekly doses) and maintenance courses (three doses weekly starting at month 3) with optional maintenance at 6, 12, 18, 24, and 30 mo.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Coprimary endpoints were safety and 6-mo complete response (CR) rate. Secondary endpoints included 3-mo CR rate and duration of CR; 95% confidence intervals were calculated using the Clopper-Pearson method.

RESULTS AND LIMITATIONS

At data cut-off (September 29, 2020), 24 patients were enrolled (cohort 1A, n = 12; cohort 1B, n = 12), and the recommended BCG dose was 50 mg in cohort 1B. Four patients (33%) had adverse events (AEs) leading to BCG dose modification/interruption. Three patients (25%) in cohort 1A reported atezolizumab-related grade 3 AEs; cohort 1B had no atezolizumab- or BCG-related grade ≥3 AEs. No grade 4/5 AEs were reported. The 6-mo CR rate was 33% in cohort 1A (median duration of CR, 6.8 mo) and 42% in cohort 1B (median duration of CR, not reached [≥12 mo]). These results are limited by the small sample size of GU-123.

CONCLUSIONS

In this first report of the atezolizumab-BCG combination in NMIBC, atezolizumab ± BCG was well tolerated, with no new safety signals or treatment-related deaths. Preliminary results suggested clinically meaningful activity; the combination favoured a longer duration of response.

PATIENT SUMMARY

We studied atezolizumab with and without bacille Calmette-Guérin (BCG) to determine whether this combination was safe and had clinical activity in patients with high-risk noninvasive bladder cancer (high-grade bladder tumours that affect the outermost lining of the bladder wall) that has previously been treated with BCG and is still present or occurred again. Our results suggest that atezolizumab with or without BCG was generally safe and could be used to treat patients unresponsive to BCG.

Abstract 612: Control of the Basal Molecular Subtype of Murine Bladder Cancer by Adaptive Immunity

Introduction: Developing optimized bladder cancer mouse models that can be used in the evaluation of immune based therapeutics remains a high priority in ongoing research.Experimental Procedures: In previous work by our collaborators, murine cell lines were generated that recapitulate the basal (BBN964, BBN966, and BBN975) molecular subtype of human bladder cancer (Saito et al. Cancer Res. 2018;78(14):3954-3968). Here we compared their tumorigenicity and growth rates in immunocompetent C57BL/6 mice and in immunodeficient Rag1-KO mice lacking B and T cells. Changes in the tumor and stromal compartments were correlated with the differences in growth rates observed. Observations and New Data: Tumors derived from all three BBN basal cell lines grew robustly in Rag1-KO mice (10/10 BBN964 tumors, 19/19 BBN966 tumors and 19/19 BBN975 tumors >100 mm3 by 10 weeks post-injection). Conversely, very few tumors grew in immunocompetent (C57BL/6, e.g. B6) mice (0/9 BBN964 at 8 weeks, 0/17 BBN966 at 16 weeks, 4/15 BBN975 at 9 weeks). BBN966 tumors conditioned to grow in Rag1-KO mice were also highly tumorigenic when they were subsequently transferred into immunocompetent mice (Rag1-KO ◊ B6, 16/20 mice with tumors >100 mm3 at 4 weeks), and they displayed increased tumorigenicity when they were reintroduced into immunodeficient mice (Rag1-KO ◊ Rag1-KO, 20/20 mice with tumors >100 mm3 at 3 weeks). BBN966 tumors harvested from B6 mice and passaged in vitro for 5 weeks maintained tumorigenicity when reimplanted into immunocompetent mice, and BBN966 tumors grown in female B6 mice grew robustly when transferred into male B6 mice. Bulk RNA sequencing of tumors comparing the BBN966 Rag1-KO (1st passage) to BBN966 Rag1-KO (2nd passage) demonstrated decreased expression of genes associated with tumor infiltrating macrophages in the 2nd passage tumors. Conclusions: Our results demonstrate that basal BBN syngeneic bladder tumors display markedly different growth rates in wild-type and T- and B-cell-deficient mice. The results suggest that adaptive immunity controls basal bladder cancer tumorigenicity, which is consistent with the immune infiltrated landscape observed in basal human bladder cancers. Further results described in this poster will include deeper molecular characterizations of the immune microenvironments of these tumors.

Citation Format: Burles Avner Johnson, Mingxiao Feng, Woonyoung Choi, Gabriela Colocho, Alyssa Arbuiso, Samuel Jin, Adam K. Aragaki, Charles Ruland, Stanley Rapiey, Noah M. Hahn, David J. McConkey. Control of the Basal Molecular Subtype of Murine Bladder Cancer by Adaptive Immunity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 612.

A Phase II Trial of Guadecitabine plus Atezolizumab in Metastatic Urothelial Carcinoma Progressing after Initial Immune Checkpoint Inhibitor Therapy

PURPOSE

Based on preclinical evidence of epigenetic contribution to sensitivity and resistance to immune checkpoint inhibitors (ICI), we hypothesized that guadecitabine (hypomethylating agent) and atezolizumab (anti-PD-L1) together would potentiate a clinical response in patients with metastatic urothelial carcinoma (UC) unresponsive to initial immune checkpoint blockade therapy.

PATIENTS AND METHODS

We designed a single arm Phase II study (NCT03179943) with a safety run-in to identify the recommended phase II dose of the combination therapy of guadecitabine and atezolizumab. Patients with recurrent/advanced urothelial carcinoma who had previously progressed on ICI therapy with PD-1 or PD-L1 targeting agents were eligible. Pre-planned correlative analysis was performed to characterize peripheral immune dynamics and global DNA methylation, transcriptome, and immune infiltration dynamics of patient tumors.

RESULTS

Safety run-in enrolled 6 patients and Phase II enrolled 15 patients before the trial was closed for futility. No dose-limiting toxicity was observed. Four patients, with best response of stable disease, exhibited extended tumor control (8-11 months) and survival (>14 months). Correlative analysis revealed lack of DNA demethylation in tumors after 2 cycles of treatment. Increased peripheral immune activation and immune infiltration in tumors after treatment correlated with progression-free survival and stable disease. Furthermore, high IL-6 and IL-8 levels in the patients' plasma associates with short survival.

CONCLUSIONS

No RECIST responses were observed after combination therapy in this trial. Although we could not detect the anticipated tumor-intrinsic effects of guadecitabine, the addition of hypomethylating agent to ICI therapy induced immune activation in a few patients, which associated with longer patient survival.

Evaluation of clinical benefit of sacituzumab govitecan (SG) following enfortumab vedotin (EV) in advanced urothelial cancer (UC): Real-world experience

523

Background: In the TROPHY study, 8.8% of the 113 patients (pts) were enrolled post EV treatment, with ORR to SG of 30% in that small subset. Response to SG post EV in real world populations has not been previously reported. SG has accelerated FDA approval for treatment refractory UC, with ORR of 27% in the TROPHY-U-01 trial. SG was developed contemporaneously to EV, which like SG, is also an antibody-drug conjugate (ADC), composed of an alternate antibody linker and chemotherapy payload. The EV ORR is 40-52% in single agent studies, and outcomes following SG to EV have not been reported. Optimal therapy sequence for advanced UC, concerns for cross resistance between ADCs and other targeted therapies, and biomarker selection for agents is underexplored. We describe clinical outcomes in pts with advanced UC treated with SG following EV. Methods: In this retrospective study of pts with UC treated with SG after progression on EV at the Johns Hopkins Greenberg Bladder Cancer Institute between November 2020 and October 2022, 17 pts were identified. Fourteen received SG in the next line following EV, 3 had other interval therapies between EV and SG. Response was determined by physician assessed RECIST criteria. All pts were response evaluable for prior EV. Three pts died shortly after C1 SG without imaging and were not response evaluable. Results: In our cohort 8 (47%) pts were female, 3 (17.6%) were African-American and 14 (82.4%) were Caucasian. Mean age was 68.3 years. Primary location was bladder for 9 (52.9%) pts and UTUC for 7 (41.2%). One (5.9%) patient had disease in both primary sites. Two (11.8%) pts had lymph node only disease, 8 (47.1%) had metastatic disease in the lungs, 6 (35.3%) in the liver and 1(5.9%) in bone. Mean number of EV cycles was 5.9 (1-12) and PFS was 5.9 months. Best EV response was CR in 1 (5.9%), PR in 10 (58.8%), SD in 2 (11.8%) and PD in 4 (23.5%) pts. SG was dose reduced in C1 with prophylactic growth factor support in 13/17 pts in this heavily pretreated population. Mean number of SG cycles was 3.8 (1.5-6). Best SG response for the 14 response evaluable pts was PR for 3 (21.4%) pts and SD for 3 (21.4%), for a clinical benefit (CR+PR+SD) rate of 42.8%. Eight pts had best response of PD (57.1%). SG discontinuation was for PD in 8 pts (57.1%) and 4 (28.6%) due to functional decline or toxicity. One patient had PD to SG in C2 but received 3 additional cycles due to therapeutic benefit. Three (21.4%) pts continue SG, after 6 cycles with PR and after 5 and 4 cycles with SD. For 14 response evaluable pts, the PFS on SG was 2.4 months. Conclusions: In this retrospective analysis, pts with advanced UC and PD following EV had meaningful clinical benefit rate to SG of 42.8% despite dose reduction in this small late line cohort. Defining optimal sequence of ADCs and other therapies in UC remains an unmet need. Updated data will be presented.

Antitumor immunity as the basis for durable disease-free, treatment-free survival (DDFTFS) in patients with metastatic urothelial cancer (mUC)

536

Background: Cisplatin-based chemotherapy has been associated with functional cures (i.e., DDFTFS) in a small subset of patients with mUC. However, the mechanistic basis for this phenomenon has remained elusive. Immune checkpoint blockade may enhance the ability of cisplatin-based chemotherapy to cure mUC, particularly if the latter is achieved by promoting antitumor immunity. From a phase II trial evaluating a phased schedule of gemcitabine and cisplatin (GC) followed by GC plus Ipilimumab (Ipi) for mUC, 4/36 patients were treatment-free disease-free >7 years after initiation of treatment. We sought to identify the immunological mechanisms associated with functional cure of such patients. Methods: Whole exome sequencing was performed on pre-treatment archival tumor tissue. Neoantigen binding affinity was predicted using NetMHCcons. Neoantigen-specific T cell response was assessed via IFNγ ELISpot assays after co-culture of patient-derived peripheral blood CD4+ and CD8+ T cells with autologous neoantigen-pulsed antigen presenting B cells. Serum protein soluble analytes were measured using the Olink Target 96 Immuno-Oncology Panel at the pre-treatment, post-GC, and post-GC+Ipi timepoints. Results: CD4+ and CD8+ neoantigen-specific T cell reactivity was measured at serial timepoints in 2 patients achieving DDFTFS and 5 patients not achieving DDFTFS. Strikingly, peripheral blood CD4+ and CD8+ T cell reactivity to a predicted neoantigen emerged on cycle 6 day 1 (after 2 cycles of GC followed by 4 cycles of GC + Ipi) in 2/2 patients achieving DDFTFS (variant in TP53 or DHX9) but in 0/5 patients not achieving DDFTFS. Peripheral serum proteomic analysis at serial timepoints (n = 35 patients) revealed that pre-treatment, patients achieving DDFTFS demonstrated an immune activated phenotype with elevations in cytotoxic adaptive immunity markers and immune checkpoints (Table). After the addition of Ipi, patients achieving DDFTFS demonstrated decreased markers of tumor-promoting inflammation but increased markers of adaptive immunity, co-stimulation, and cytotoxicity. Conclusions: Anti-tumor immunity may underlie functional cures achieved in patients with mUC treated with cisplatin-based chemotherapy +/- immune checkpoint blockade. Probing the mechanistic basis for DDFTFS may facilitate the identification of pre- and on-treatment features, and therapeutic components and sequences, necessary to extend this ultimate therapeutic goal to a larger subset of patients. [Table: see text]

Intravesical gemcitabine and docetaxel in the treatment of BCG-naïve non–muscle invasive urothelial carcinoma of the bladder: Updates from a phase 2 trial

507

Background: Combination intravesical Gemcitabine and Docetaxel (GEMDOCE) has demonstrated benefit for bacillus Calmette-Guérin (BCG) unresponsive non-muscle invasive bladder cancer (NMIBC) in retrospective series and is now being widely utilized as salvage therapy. BCG therapy is fraught with frequent drug shortages and some patients are unable to tolerate BCG due to side effects. Given ongoing BCG shortages as well as the promising efficacy and tolerability of GEMDOCE as a salvage therapy, our objective was to investigate the safety and efficacy of intravesical GEMDOCE for high-risk (HR) BCG-naïve NMIBC in a prospective manner. Methods: This study is an IRB-approved prospective single-arm open-label phase II trial for patients with BCG-naïve HR NMIBC. Intravesical gemcitabine (1,000 mg)/docetaxel (40 mg) in 100mL normal saline is given weekly for 6 weeks as induction followed by monthly maintenance therapy for 2 years among responders. The primary endpoint was 3-month complete response (CR), defined as a negative bladder biopsy 6 weeks after induction treatment. Secondary endpoints included adverse events (AE) and 12-month CR. Results: To date, the study has fully accrued with 25 patients enrolled from July 2020-August 2022. The pre-trial pathologic stages in our cohort were as follows: HGT1 with CIS (n = 7), HGT1 without CIS (n = 6), HGTa (n = 9), and CIS alone (n = 3) (Table). All 25 patients who completed induction therapy demonstrated CR at 3 months. Eight out of 9 (89%) patients with at least 12 months of follow-up demonstrated continued CR. One patient with HGT1 + CIS on enrollment developed a recurrence at 9 months with HGTa. No enrolled patients have undergone radical cystectomy. Grade 1 AEs were common (19/25 patients, 76%) including hematuria, urinary frequency, urgency, and fatigue. Two patients (8%) experienced a Grade 3 AE including urinary retention and UTI requiring hospitalization and intravenous antibiotics. Conclusions: In this ongoing single-arm phase II trial, GEMDOCE appears to be well-tolerated with promising short-term efficacy for patients with BCG-naïve HR NMIBC. [Table: see text]

Atezolizumab with platinum and etoposide chemotherapy followed by cystectomy for patients with localized small cell neuroendocrine bladder cancer

TPS599

Background: Small cell bladder cancer (SCBC) is a rare aggressive bladder cancer (BC) variant comprising <1% of BC. Recommended front line etoposide and platinum chemotherapy for SCBC is extrapolated from small cell lung cancer (SCLCA) studies. Data describing small cell bladder cancer treatment are predominantly retrospective. Substitution of etoposide for gemcitabine with cis or carboplatin is widely accepted. This extrapolation is based on histologic similarity between the rare SCBC, and more common SCLCA. Recently, several teams have shown DNA mutation patterns are also more consistent between SCBC and SCLCA, compared to SCBC and urothelial bladder cancers, further supporting the divergence in treatment. These patterns which characterize this “neuronal” subgroup in the TCGA dataset, also reinforce this group has the poorest OS outcome vs other subtypes. Patients with SCBC are nearly uniformly excluded from BC trials, and thus the response to checkpoint inhibition and other novel therapies in SCBC is unknown. As SCBCs often respond to, then quickly recur post chemotherapy, novel active therapies are needed. Immune checkpoint blockade with anti-PD(L)1 antibodies is clinically active, leading to objective responses in approximately 15-25% of patients with urothelial cancer, and 33% in biomarker selected patients with SCLCA. In IMpower133, Atezolizumab + carboplatin + etoposide vs chemotherapy alone demonstrated significant OS advantage (12.3 vs 10.3 months) in frontline ES SCLCA, a practice changing milestone. Like urothelial bladder and SCLCA, we believe SCBC may have dramatic response to checkpoint inhibitors, as shown in small case series from our team and others. Methods: Patients with invasive (cT1-cT4) small cell/neuroendocrine carcinoma of the bladder (MIBC), with or without urothelial cancer component, who are eligible for radical cystectomy and platinum chemotherapy and immunotherapy will be enrolled. Patients with N1 disease within the true pelvis are eligible. Atezolizumab 1200 mg IV Day 1 of every 21 day cycle with etoposide and investigator choice cisplatin or carboplatin chemotherapy x 4 neoadjuvant cycles will be delivered. The primary objective is to assess pathologic complete response rate following protocol therapy. Following cystectomy, Atezolizumab maintenance Q 21 days will continue until unacceptable toxicity or loss of clinical benefit for up to 1 year (e.g., 16 cycles). With type I and type II error rates of 5 and 10% respectively, the first stage will consist of 15 patients. If 6 or fewer patients respond, the study will terminate after the first stage. Otherwise, accrual will continue to 34 patients. If 17 or fewer patients respond at the end of the second stage, the study will terminate after the second stage. If 18 or more patients respond, accrual will continue to 63 patients. Secondary endpoints include rates of DFS and OS. Clinical trial information: NCT05312671 .

Comparison of clinicopathological characteristics, gene expression profiles, mutational analysis, and clinical outcomes of pure and mixed small-cell carcinoma of the bladder

AIMS

Small cell bladder carcinoma (SCBC) is a rare, divergent form of urothelial carcinoma (UC). We aimed to determine whether pure (n = 16) and mixed (SCBC and UC; n = 30) tumours differed in pathology, gene expression characteristics, genetic alterations, and clinical outcomes.

METHODS AND RESULTS

Forty (87%) patients received first-line chemotherapy. Twenty-nine patients had no metastatic disease at diagnosis and underwent radical cystectomy. There were no differences in age, sex, race distribution, tumour size, stage at presentation, therapy response with pathological downstaging to ≤ypT1N0, or overall or progression-free survival (PFS) between pure and mixed tumours. There was a longer PFS among downstaged chemotherapy-responding tumours ≤ypT2N0M0 than among unresponsive tumours ≥ypT2 ≥ yN1M1 (P = 0.001). Patients who achieved pathological downstaging with neoadjuvant chemotherapy (n = 10) were stage cT2N0M0 at the time of diagnosis and were alive at the last follow-up (median 37 months), while 46% of patients who failed to achieve pathological downstaging were alive at the last follow-up (median 38 months; P = 0.008). RNA sequencing showed that the UC of mixed SCBC had similar neural expression signatures to pure SCBC. DNA sequencing revealed alterations in TERT (83%), P53 (56%), ARID1A (28%), RB1 (22%), and BRCA2 (11%). Immunohistochemistry for RB1 showed loss of expression in 18/19 (95%) patients, suggesting frequent pathway downregulation despite a low prevalence of RB1 mutation.

CONCLUSION

Patients with pure and mixed SCBC have similar outcomes and these outcomes are determined by the pathological stage at RC and are best among patients who have pathological downstaging after NAC.

Enfortumab Vedotin-related Cutaneous Toxicity and Radiographic Response in Patients with Urothelial Cancer: A Single-center Experience and Review of the Literature

Enfortumab vedotin (EV) is an antibody-drug conjugate approved for the treatment of refractory advanced urothelial cancer. Cutaneous toxicity is well described but has not been correlated with response. In this retrospective single-center study, data from patients treated with more than one dose of EV between December 2017 and June 2022 were analyzed. Of 56 patients with a median age of 69 yr, 41 (73.2%) were male and 27 (48.2%) had any-grade skin toxicity. For all 51 patients evaluable by physician-assessed Response Evaluation Criteria in Solid Tumors (RECIST) criteria, the response rate was 41.2%. For those with cutaneous toxicity, the response rate was 57.7%; for those without cutaneous toxicity, it was 24.0% (p = 0.0145). All three patients with complete response experienced cutaneous toxicity, and two of these responses remain durable 5 and 24 mo off EV. The median starting weight and body mass index (BMI) were, respectively, 80.86 kg and 26.53 kg/m² among patients with cutaneous toxicity, and 69.37 kg and 23.29 kg/m² in patients without (p = 0.0129 and 0.0014, respectively). In this small dataset, EV-related cutaneous toxicity was more common in patients with higher weight and BMI at baseline, and was associated with disease response. Confirmation in prospective trials may confirm this association and lead to an important clinical biomarker of response.

Patient summary

We evaluated patients with urothelial cancer who were treated at our institution with enfortumab vedotin (EV). We found that patients who experienced the common side effect of any type of skin toxicity, such as rash or itching, were more likely to have improvement in their cancer from EV treatment than those who did not experience skin toxicity. Patients with higher weight and body mass index when starting EV tended to have more skin toxicity. We conclude that presence of skin toxicity might help doctors make decisions about how to manage the care of patients with EV in the future.

Identification of a naturally-occurring canine model for early detection and intervention research in high grade urothelial carcinoma

BACKGROUND

Early detection and intervention research is expected to improve the outcomes for patients with high grade muscle invasive urothelial carcinoma (InvUC). With limited patients in suitable high-risk study cohorts, relevant animal model research is critical. Experimental animal models often fail to adequately represent human cancer. The purpose of this study was to determine the suitability of dogs with high breed-associated risk for naturally-occurring InvUC to serve as relevant models for early detection and intervention research. The feasibility of screening and early intervention, and similarities and differences between canine and human tumors, and early and later canine tumors were determined.

METHODS

STs (n=120) ≥ 6 years old with no outward evidence of urinary disease were screened at 6-month intervals for 3 years with physical exam, ultrasonography, and urinalysis with sediment exam. Cystoscopic biopsy was performed in dogs with positive screening tests. The pathological, clinical, and molecular characteristics of the "early" cancer detected by screening were determined. Transcriptomic signatures were compared between the early tumors and published findings in human InvUC, and to more advanced "later" canine tumors from STs who had the typical presentation of hematuria and urinary dysfunction. An early intervention trial of an oral cyclooxygenase inhibitor, deracoxib, was conducted in dogs with cancer detected through screening.

RESULTS

Biopsy-confirmed bladder cancer was detected in 32 (27%) of 120 STs including InvUC (n=29, three starting as dysplasia), grade 1 noninvasive cancer (n=2), and carcinoma in situ (n=1). Transcriptomic signatures including druggable targets such as EGFR and the PI3K-AKT-mTOR pathway, were very similar between canine and human InvUC, especially within luminal and basal molecular subtypes. Marked transcriptomic differences were noted between early and later canine tumors, particularly within luminal subtype tumors. The deracoxib remission rate (42% CR+PR) compared very favorably to that with single-agent cyclooxygenase inhibitors in more advanced canine InvUC (17-25%), supporting the value of early intervention.

CONCLUSIONS

The study defined a novel naturally-occurring animal model to complement experimental models for early detection and intervention research in InvUC. Research incorporating the canine model is expected to lead to improved outcomes for humans, as well as pet dogs, facing bladder cancer.

Collaborative study from the Bladder Cancer Advocacy Network for the genomic analysis of metastatic urothelial cancer

Urothelial Cancer - Genomic Analysis to Improve Patient Outcomes and Research (NCT02643043), UC-GENOME, is a genomic analysis and biospecimen repository study in 218 patients with metastatic urothelial carcinoma. Here we report on the primary outcome of the UC-GENOME-the proportion of subjects who received next generation sequencing (NGS) with treatment options-and present the initial genomic analyses and clinical correlates. 69.3% of subjects had potential treatment options, however only 5.0% received therapy based on NGS. We found an increased frequency of TP53E285K mutations as compared to non-metastatic cohorts and identified features associated with benefit to chemotherapy and immune checkpoint inhibition, including: Ba/Sq and Stroma-rich subtypes, APOBEC mutational signature (SBS13), and inflamed tumor immune phenotype. Finally, we derive a computational model incorporating both genomic and clinical features predictive of immune checkpoint inhibitor response. Future work will utilize the biospecimens alongside these foundational analyses toward a better understanding of urothelial carcinoma biology.

Health-related quality of life (HRQoL) for patients with advanced/metastatic urothelial carcinoma (UC) enrolled in KEYNOTE-052 who are potentially platinum ineligible

4561

Background: Frontline cisplatin-based chemotherapy improves survival in patients (pts) with UC, but ̃50% are cisplatin-ineligible owing to poor performance status or comorbidity. The definition of platinum ineligibility is not standardized; hence, treatment decisions are almost solely made by clinical judgment. Pembrolizumab (pembro) showed antitumor activity and manageable toxicity as frontline therapy in 370 cisplatin-ineligible pts in the single arm, phase 2 KEYNOTE-052 trial (NCT02335424). We present effects of pembro on HRQoL of pts in KEYNOTE-052 who were potentially platinum ineligible in this exploratory analysis. Methods: Eligible pts for KEYNOTE-052 were adults with no prior systemic chemotherapy for advanced/metastatic UC, ECOG PS ≤2, and measurable disease per RECIST v1.1 by blinded independent central review. Pembro 200 mg IV was administered Q3W for up to 2 y. Clinical characteristics of frail pts (platinum ineligible) were identified by extensive review of real-world treatment patterns and relevant literature. Consequently, platinum ineligibility was defined as having an ECOG PS ≥2 plus ≥1 of the following: visceral disease, creatinine clearance < 60 mL/min, or age ≥80 y. HRQoL was assessed using the EORTC QLQ-C30 and EQ-5D-3L during the first 4 cycles, then every 2 cycles for 1 year or until treatment discontinuation (whichever occurred first), and at least 30 days after treatment discontinuation. Key end points were change from baseline per the QLQ-C30 global health status (GHS)/QoL score, QLQ-C30 physical functioning subscale, and EQ-5D visual analog scale (VAS). The minimum important difference (MID) was 10 for QLQ-C30 score change (improved: ≥10; stable: –10 to 10; deteriorated: –10 or less); MID for VAS score change was 7 (improved: ≥7; stable: –7 to 7; deteriorated: –7 or less). Results: Median age for 143 pts was 75 y (range, 34-91); 129 pts (90.2%) had visceral disease; 142 (99.3%) had ECOG PS 2; 1 had ECOG PS 3 (enrolled in error). Compliance rate for HRQoL questionnaires was 93.7% at baseline. At the prespecified analysis time of week 9, 77.6% of pts had improved (n = 51) or stable (n = 60) QLQ-C30 GHS/QoL scores, 64.3% had improved (n = 35) or stable (n = 57) QLQ-C30 physical functioning scores, and 62.2% had improved (n = 56) or stable (n = 33) EQ-5D VAS scores. These scores were stable throughout the HRQoL assessment period for pts who continued pembro. Conclusions: In this exploratory analysis, pembro maintained HRQoL for pts with advanced/metastatic UC in KEYNOTE-052 who were potentially platinum-ineligible per the above criteria. Together with the efficacy and safety data from KEYNOTE-052, these data suggest that pembro monotherapy is a valuable treatment option for select pts with advanced UC who are more senior and/or deemed medically frail. Clinical trial information: NCT02335424.

EA8185: Phase 2 study of bladder-sparing chemoradiation (chemoRT) with durvalumab in clinical stage III, node-positive urothelial carcinoma (INSPIRE), an ECOG-ACRIN/NRG collaboration

TPS4617

Background: Patients [pts] withlymph node positive (LN+), non-metastatic bladder cancer (BC) have a better prognosis than those with metastatic (M1) disease. However, this population is under-represented in advanced bladder trials and ineligible for bladder-sparing trials. Therefore, there have been no larger prospective trials establishing the standard of care in LN+ BC. Given the promise of immunotherapy in advanced BC and potential synergy between immunotherapy and radiation, INSPIRE was designed to determine the role of concurrent and adjuvant durvalumab (durva) in this patient population when treated with induction chemotherapy (IC) followed by concurrent chemoRT. Methods: This is a randomized phase II study that is enrolling BC pts with stage III [N1-3 M0], pure or mixed urothelial cancer. Pts must have received ≥3 cycles of IC [either before or after registration, prior to randomization] without progression. LN+ is defined as radiologically LN ≥1.0 cm in short axis, with or without biopsy prior to IC. As long as pts do not progress on induction chemotherapy, they will be randomized to chemoRT+/- durva using 5 stratification factors (Simon Pocock minimization method) a) IC prior vs. post registration b) cisplatin vs non-cisplatin regimen during RT c) LN size d) response to IC e) extent of TURBT. Pts on the chemoRT+durva arm will get chemotherapy per physician choice + IMRT + 3 x doses of Q3wk durva for 6.5-8 wks, whereas those on the control arm will get chemoRT alone. The primary end point is clinical complete response [CR], defined as no radiologically measurable disease in the LNs and negative cystoscopy and bladder biopsy 8-10 weeks post-chemoRT +/- durva. Pts on the chemoRT + durva arm who have a CR or clinical benefit ( > T0 and ≤T2 in bladder per cystoscopy, biopsy + CR/PR/SD in LN by imaging) will get adjuvant Q4wk durva for 9 doses, while those on the chemoRT arm will undergo observation. Secondary end points include OS, PFS, bladder-intact event-free survival, rate of toxicity and salvage cystectomy. This study is designed to detect an improvement of 25% in clinical CR between both arms (37.5% to 62.5%). A total accrual of 114 pts (in order to enroll 92 evaluable pts) will provide 81% power to detect this difference using a Fisher’s exact test (assuming 10% drop out + anticipating that 20% chemotherapy-naïve pts will progress post IC). We are banking blood and primary tumor tissue pre- and post-chemoRT in both groups. The study was activated in August 2020 and accrual is ongoing. We expanded eligibility to include N3 in 9/2021. INSPIRE is the first prospective study designed for only LN+ BC and will define both short-term and long-term outcomes for bladder sparing in this patient population and has the potential to define a new treatment strategy for stage III BC. Clinical trial information: NCT04216290.

Eight-year survival rates by baseline prognostic groups in patients with metastatic hormone-sensitive prostate cancer (mHSPC): An analysis from the ECOG-ACRIN 3805 (CHAARTED) trial

5081

Background: To date there is no prospective survival data beyond 5 years for patients treated with ADT with or without docetaxel (D) when analyzed by well-defined baseline prognostic risk groups and treatment arms. In this updated analysis of the CHAARTED trial, we report the 8-year survival rate based on disease volume and metachronous vs. de novo metastatic disease status with ADT without or with docetaxel. Methods: An updated survival sweep was conducted in February 2022. Patients were prospectively identified by the state of metastatic disease as metachronous (prior local therapy) vs. de novo and low volume (LV) vs. high volume (HV; visceral and/or ≥4 bone metastases with one lesion beyond the vertebral bodies or pelvis) disease. Overall survival (OS) was defined as time from randomization to death or date last known alive and calculated using the Kaplan-Meier method. Results: Of the 790 patients randomized (last patient enrolled December 2012), 238 patients were still alive with a median follow up of 9.7 years for patients still alive. Median OS in the overall population was 60.4 and 47.2 mos in the ADT+ D and ADT arms respectively (Table; HR: 0.77; 95% CI: 0.65, 0.92; p=0.004). ADT+ D was associated with significantly higher 8-yr OS rate (28.5%) compared to ADT arm (15.4%; HR: 0.67; 95% CI: 0.53, 0.84; p=0.0005) in the de novo HV group (n=421). Notably, the 8-yr OS rates were almost doubled for patients with HV disease with early docetaxel (16% vs.30.2%, p<.0001) and this was seen in patients with both de novo and metachronous HV mHSPC. Conclusions: In this long-term updated analysis, ADT+D continued to demonstrate significantly improved OS in the overall population and this is still most clearly evident in patients with de novo HV mHSPC. Our findings highlight the role of baseline prognostic risk groups in predicting longer term survival and benefits from treatment intensification. Clinical trial information: NCT00309985. [Table: see text]

EA8185: Phase 2 study of bladder-sparing chemoradiation (chemoRT) with durvalumab in clinical stage III, node positive urothelial carcinoma (INSPIRE), an ECOG-ACRIN/NRG collaboration

TPS594

Background: Patients [pts] withlymph node positive (LN+), non-metastatic bladder cancer (BC) have a better prognosis than those with metastatic (M1) disease. However, this population is under-represented in advanced bladder trials and ineligible for bladder-sparing trials. Therefore, there have been no larger prospective trials establishing the standard of care in LN+ BC. Given the promise of immunotherapy in advanced BC and potential synergy between immunotherapy and radiation, INSPIRE was designed to determine the role of concurrent and adjuvant durvalumab (durva) in this patient population when treated with induction chemotherapy (IC) followed by concurrent chemoRT. Methods: This is a randomized phase II study that is enrolling BC pts with stage III [N1-3 M0], pure or mixed urothelial cancer. Pts must have received ≥3 cycles of IC [either before or after registration, prior to randomization] without progression. LN+ is defined as radiologically LN ≥1.0 cm in short axis, with or without biopsy prior to IC. As long as pts do not progress on induction chemotherapy, they will be randomized to chemoRT+/- durva using 5 stratification factors (Simon Pocock minimization method) a) IC prior vs. post registration b) cisplatin vs non-cisplatin regimen during RT c) LN size d) response to IC e) extent of TURBT. Pts on the chemoRT+durva arm will get chemotherapy per physician choice + IMRT + 3 x doses of Q3wk durva for 6.5-8 wks, whereas those on the control arm will get chemoRT alone. The primary end point is clinical complete response [CR], defined as no radiologically measurable disease in the LNs and negative cystoscopy and bladder biopsy 8-10 weeks post-chemoRT +/- durva. Pts on the chemoRT + durva arm who have a CR or clinical benefit (>T0 and ≤T2 in bladder per cystoscopy, biopsy + CR/PR/SD in LN by imaging) will get adjuvant Q4wk durva for 9 doses, while those on the chemoRT arm will undergo observation. Secondary end points include OS, PFS, bladder-intact event-free survival, rate of toxicity and salvage cystectomy. This study is designed to detect an absolute improvement of 25% in clinical CR between both arms (37.5% to 62.5%). The accrual goal is 114, assuming 10% drop out + anticipating that 20% chemotherapy-naïve pts will progress post IC, and 92 evaluable pts that will provide 81% power to detect this difference using a Fisher’s exact test. We are banking blood and primary tumor tissue pre- and post-chemoRT in both groups. The study was activated in August 2020 and accrual is ongoing. We expanded eligibility to include N3 in 9/2021. INSPIRE is the first prospective study designed for only LN+ BC and will define both short-term and long-term outcomes for bladder sparing in this patient population and has the potential to define a new treatment strategy for stage III BC. Clinical trial information: NCT04216290.

Atezolizumab (atezo) with or without Bacille Calmette-Guérin (BCG) in patients (pts) with high-risk nonmuscle-invasive bladder cancer (NMIBC): Results from a phase Ib/II study

493

Background: Standard treatment (tx) for high-risk NMIBC is transurethral resection of bladder tumor (TURBT) followed by BCG induction and maintenance. However, ≈50% of pts experience recurrence and/or progression after tx and may be ineligible for or refuse cystectomy. The PD-L1/PD-1 pathway may be involved with immune escape in NMIBC following BCG exposure. Here, we report results of atezo (anti–PD-L1) ± BCG in BCG-unresponsive, high-risk NMIBC. Methods: This multicenter study (NCT02792192) enrolled pts with BCG-unresponsive NMIBC with carcinoma in situ who had repeat TURBT. Cohort 1A and 1B pts received atezo 1200 mg IV q3w for ≤96 wk. Cohort 1B pts also received standard BCG induction (qw × 6 doses) and maintenance (qw × 3 doses at 3 mo), with optional maintenance courses at 6, 12, 18, 24, and 30 mo. For cohort 1B only, de-escalation was allowed for ≤3 BCG dose levels (full dose 50 mg, 66% and 33% of full dose). Co-primary outcomes were safety and complete response (CR) rate at 6 mo (6-mo bladder biopsy required). Duration of CR and 3-mo CR rate (key secondary outcomes) and 12-mo CR rate (exploratory) were also shown. Results: Cohorts 1A and 1B enrolled 12 pts each. Median age was 74 y; most pts had ECOG PS 0 (n = 7 [58%] in each cohort). At data cutoff (Sep 29, 2020), median atezo tx duration was 22.7 wk in cohort 1A and 31.6 wk in 1B. Following dose de-escalation in cohort 1B, the recommended BCG dose was 50 mg. BCG dose modification/interruption occurred in 4 pts (33%) due to an AE. The most common reason for tx discontinuation was disease recurrence or progression in both cohorts. Three pts (25%) in cohort 1A had atezo-related Gr 3 AEs (most common: maculopapular rash, n = 2); no atezo- or BCG-related Gr ≥3 AEs were seen in cohort 1B. Three dose-limiting toxicities occurred (1 [8%] in cohort 1A and 2 [17%] in cohort 1B), all reported as AEs of special interest. No Gr 4/5 AEs were reported. CRs, which appeared durable, were seen in both cohorts (Table). Conclusions: In this first report of atezo + BCG in NMIBC, atezo as mono- and combination therapy was well tolerated, with no new safety signals or tx-related deaths. Preliminary data suggested clinically meaningful activity, especially with atezo + BCG, requiring confirmation in a larger setting. Clinical trial information: NCT02792192. [Table: see text]

First-line pembrolizumab in advanced urothelial carcinoma: Clinical parameters associated with efficacy in the phase 2 KEYNOTE-052 and phase 3 KEYNOTE-361 trials

521

Background: First-line treatment with pembrolizumab (pembro) monotherapy has shown durable clinical activity in selected patients (pts) with advanced/unresectable or metastatic urothelial carcinoma (UC). In a pooled population of pts with advanced UC from the single-arm phase 2 KEYNOTE-052 (NCT02335424) and the randomized, open-label, phase 3 KEYNOTE-361 (NCT02853305) studies, this exploratory analysis evaluated the relationship between baseline characteristics and clinical outcomes of first-line pembro monotherapy. Methods: Cisplatin-ineligible pts with advanced UC were enrolled in KEYNOTE-052 and chemotherapy-naive pts with advanced UC were enrolled in KEYNOTE-361. For analysis of predictive factors for ORR and OS in pembro-treated pts, the purposeful selection method was used to build the multivariable logistic regression model (ORR) and multivariable Cox model (OS), beginning with a univariable analysis of each independent variable. Any variable in the univariate model with P < 0.10 was a candidate for the multivariate model. The stepwise selection method was used to select the variables in the final model. Significance of the final model was set at P < 0.05. Data cutoff dates were September 26, 2020 (KEYNOTE-052) and April 29, 2020 (KEYNOTE-361). Results: This pooled analysis included 681 pts treated with pembro monotherapy (KEYNOTE-052, N = 374; KEYNOTE-361, N = 307 [170 were cisplatin ineligible]). Median follow-up was 51.9 mo (range, 22.0-65.3). ORR was 29.4% (95% CI, 26.0-32.9; 69 CRs, 131 PRs), and median DOR was 33.2 mo (range, 1.4+ to 60.7+). Median OS was 12.5 mo (95% CI, 11.0-14.6). By multivariate analysis, independent factors significantly associated with higher ORR were PD-L1 status (combined positive score [CPS] ≥10 vs CPS < 10; odds ratio [OR], 1.90 [95% CI, 1.33-2.71]; P = 0.0004), site of metastasis (lymph node only vs visceral disease; OR, 1.66 [95% CI, 1.06-2.59]; P = 0.0265), liver involvement (absent vs present; OR, 1.75 [95% CI, 1.06-2.89]; P = 0.0294), and baseline hemoglobin level ≥10 vs < 10 g/dL; OR, 2.17 [95% CI, 1.09-4.31]; P = 0.0276). Multivariate analysis of OS is displayed in the Table. Conclusions: This exploratory multivariate analysis identified numerous factors, including PD-L1–positive status (CPS ≥10), lymph node only metastasis, and lower ECOG PS score, associated with improved clinical outcomes in pts with advanced UC treated with first-line pembro monotherapy. Clinical trial information: NCT02335424 and NCT02853305. [Table: see text]

Post hoc analysis of the efficacy of pembrolizumab retreatment after progression of advanced urothelial carcinoma (UC) in KEYNOTE-045 and KEYNOTE-052

512

Background: Pembrolizumab (pembro) has shown efficacy in advanced/unresectable and metastatic UC (mUC). There is interest in determining whether pts should be treated subsequently with checkpoint inhibitors such as anti–PD-1 therapy if mUC responds then later progresses. Pembro retreatment after disease progression has shown efficacy in melanoma and NSCLC. This post hoc exploratory analysis investigated the efficacy of pembro retreatment for pts with advanced UC or mUC enrolled in KEYNOTE-045 and KEYNOTE-052 with a best overall response (BOR) of SD or better and whose disease progressed after discontinuation or completion of 2 y of therapy. Methods: The phase 3 KEYNOTE-045 trial (NCT02256436) was designed to compare the efficacy and safety of pembro vs chemotherapy (chemo) in pts with mUC that recurred/progressed on platinum containing chemo; ≤2 prior lines of systemic chemo for mUC were permitted. The phase 2 KEYNOTE-052 trial (NCT02335424) was designed to evaluate the efficacy and safety of first-line pembro in cisplatin-ineligible pts with advanced UC. In both studies, pembro was administered for up to 2 y; pts were eligible for retreatment if they stopped pembro after CR or had a BOR of CR, PR, or SD and completed 2 y of treatment. Pts must have investigator-confirmed radiographic PD after therapy cessation, have ECOG PS score 0-1, and not have received anticancer treatment after the last pembro dose. BOR to retreatment is reported. Results: At data cutoff for KEYNOTE-045 (Oct 1, 2020), 11 pts were retreated: 5 (45%) achieved objective response to retreatment (3 CR; 2 PR; Table) and 6 had SD, for a disease control rate (DCR; CR+PR+SD) of 100%. Median treatment-free interval was 7.7 mo (IQR, 3.6-16.5); median duration of retreatment was 11.4 mo (IQR, 7.6-12.0). Seven pts (64%) were alive at cutoff. At data cutoff for KEYNOTE-052 (Sep 26, 2020), 10 pts were retreated; 5 (50%) had objective response to retreatment (1 CR; 4 PR) and 4 had SD, for a DCR of 90%. Retreatment BOR was PD for 1 pt (10%). Median treatment-free interval was 13.0 mo (9.2-16.6); median duration of retreatment was 6.0 mo (IQR, 4.9-9.2). Four pts (40%) were alive at cutoff. Conclusions: Although the number of pts who received retreatment was small, objective responses were observed. The findings are generally consistent with observations from retreatment in other tumor types (e.g., melanoma). Clinical trial information: NCT02256436 and NCT02335424. [Table: see text]

Randomized comparator-controlled study evaluating efficacy and safety of pembrolizumab plus Bacillus Calmette-Guérin (BCG) in patients with high-risk nonmuscle-invasive bladder cancer (HR NMIBC): KEYNOTE-676 cohort B

TPS597

Background: Cohort A of the phase 2 KEYNOTE-057 study showed that pembrolizumab monotherapy provided effective antitumor activity and acceptable safety in patients with BCG-unresponsive HR NMIBC with carcinoma in situ (CIS). Pembrolizumab in combination with BCG at earlier stages of HR NMIBC might provide benefit superior to that of BCG monotherapy. The open-label, comparator-controlled, phase 3 KEYNOTE-676 study (NCT03711032) will be conducted to investigate the efficacy and safety of pembrolizumab + BCG versus BCG monotherapy in patients with HR NMIBC. Cohort A will enroll patients with persistent or recurrent HR NMIBC after BCG induction. Cohort B is a new, randomly assigned cohort that will help evaluate pembrolizumab + BCG in BCG treatment–naive patients who either never received BCG treatment or received BCG treatment > 2 years before enrollment. Methods: Cohort B of KEYNOTE-676 will enroll approximately 975 patients with blinded independent central review (BICR)–confirmed HR NMIBC (T1, high-grade Ta CIS) and Eastern Cooperative Oncology Group performance status score 0-2 who underwent cystoscopy/transurethral resection of bladder tumor ≤12 weeks before randomization and had not received BCG within the past 2 years. Patients will be randomly assigned 1:1:1 to receive pembrolizumab 400 mg intravenously (IV) every 6 weeks (Q6W) + BCG reduced maintenance (≤6 months), pembrolizumab 400 mg IV Q6W + BCG full maintenance (≤18 months), or BCG monotherapy (BCG full maintenance). Stratification factors include NMIBC stage (CIS or no CIS) and PD-L1 expression (combined positive score [CPS] ≥10 or CPS < 10), determined by central laboratory. Disease status will be assessed by use of cystoscopy, urine cytology, and biopsy (as applicable) every 12 weeks (Q12W) through year 2, then every 24 weeks through year 5; imaging with computed tomography urography will occur every 72 weeks. Adverse events (AEs) will be monitored throughout the study and up to 30 days after cessation of study treatment (90 days for serious AEs). The primary end point is event-free survival (EFS). Secondary end points include complete response rate by BICR, duration of response (DOR), 12-month DOR rate (CIS only), 24-month EFS rate, disease-specific survival, time to cystectomy, overall survival, and safety. The study is enrolling or planning to enroll at sites in Asia, Australia, Europe, North America, and South America. Clinical trial information: NCT03711032.

Neoadjuvant Nivolumab in Patients with High-risk Nonmetastatic Renal Cell Carcinoma

Neoadjuvant immune checkpoint blockade represents a novel approach for potentially decreasing the risk of recurrence in patients with nonmetastatic renal cell carcinoma (RCC). In this early phase clincal tiral, we evaluated the safety and tolerability of neoadjuvant treatment with the programmed cell death protein 1 (PD-1) inhibitor nivolumab in patients with nonmetastatic high-risk RCC. Nonprimary endpoints included objective radiographic tumor response rate, immune-related pathologic response rate, quality of life alterations, and metastasis-free and overall survival. In total, 17 patients were enrolled in this study and underwent surgery without a delay after receiving three every-2-wk doses of neoadjuvant nivolumab. Adverse events (AEs) of any grade occurred in 14 (82.4%) patients, with two (11.8%) experiencing grade 3 events. Ten (58.8%) patients experienced an AE of any grade potentially attributable to nivolumab (all grade 1-2), and no grade 4-5 AEs occurred regardless of treatment attribution. The most common AEs were grade 1 fatigue (41.2%), grade 1 pruritis (29.4%), and grade 1 rash (29.4%). All evaluable patients had stable disease as per established radiographic criteria, with one (6.7%) demonstrating features of an immune-related pathologic response. Quality of life remained stable during treatment, with improvements relative to baseline noted at ≥6 mo postoperatively. Metastasis-free survival and overall survival were 85.1% and 100% at 2 yr, respectively. PATIENT SUMMARY: In this study, we evaluated the safety and tolerability of preoperative administration of three doses of the immune checkpoint inhibitor nivolumab in patients with clinically localized high-risk renal cell carcinoma. We demonstrated the safety of this approach and found that, although most patients will not experience a radiographic response to treatment, a subset may have features of an immune-related pathologic response.

OUP accepted manuscript

Background

Treatment options have been historically limited for cisplatin-ineligible patients with advanced urothelial carcinoma (UC). Given the need for alternatives to platinum-based chemotherapy, including non-chemotherapy regimens for patients with both impaired renal function and borderline functional status, in 2010 (prior to the immune checkpoint blockade era in metastatic UC), we initiated a phase II trial to test the activity of everolimus or everolimus plus paclitaxel in the cisplatin-ineligible setting.

Methods

This was an open-label phase II trial conducted within the US-based Hoosier Cancer Research Network (ClinicalTrials.gov number: NCT01215136). Patients who were cisplatin-ineligible with previously untreated advanced UC were enrolled. Patients with both impaired renal function and poor performance status were enrolled into cohort 1; patients with either were enrolled into cohort 2. Patients received everolimus 10 mg daily alone (cohort 1) or with paclitaxel 80 mg/m² on days 1, 8, and 15 of each 28-day cycle (cohort 2). The primary outcome was clinical benefit at 4 months. Secondary outcomes were adverse events, progression-free survival (PFS), and 1-year overall survival (OS). Exploratory endpoints included genomic correlates of outcomes. The trial was not designed for comparison between cohorts.

Results

A total of 36 patients were enrolled from 2010 to 2018 (cohort 1, N = 7; cohort 2, N = 29); the trial was terminated due to slow accrual. Clinical benefit at 4 months was attained by 0 (0%, 95% confidence interval [CI] 0-41.0%) patients in cohort 1 and 11 patients (37.9%, 95% CI 20.7-57.7%) in cohort 2. Median PFS was 2.33 (95% CI 1.81-Inf) months in cohort 1 and 5.85 (95% CI 2.99-8.61) months in cohort 2. Treatment was discontinued due to adverse events for 2 patients (29%) in cohort 1 and 11 patients (38%) in cohort 2. Molecular alterations in microtubule associated genes may be associated with treatment benefit but this requires further testing.

Conclusion

Everolimus plus paclitaxel demonstrates clinical activity in cisplatin-ineligible patients with metastatic UC, although the specific contribution of everolimus cannot be delineated. Patients with both impaired renal function and borderline functional status may be difficult to enroll to prospective trials. (ClinicalTrials.gov Identifier NCT01215136).

A Molecular Inquiry into the Role of Antibody-Drug Conjugates in Bacillus Calmette-Guérin-exposed Non-muscle-invasive Bladder Cancer

The treatment landscape for advanced urothelial cancer has changed dramatically owing to the US Food and Drug Administration approval and introduction of antibody-drug conjugates (ADCs), including enfortumab vedotin and sacituzumab govitecan. Efforts have begun to use these therapies in earlier disease states, specifically bacillus Calmette-Guérin (BCG)-unresponsive non-muscle-invasive bladder cancer (NMIBC). We assessed gene expression associated with these newly approved therapies in a novel cohort of treatment-naïve NMIBC tumors before and after BCG therapy. Multiple genes, including Nectin-4, Trop-2, and Her-2, exhibited increased expression after BCG therapy compared to baseline. However, few of the tumors with increased expression of ADC targets also exhibited increased PD-L1/PD-1 expression. Taken together, these data demonstrate the heterogeneous genomic landscape of BCG-exposed NMIBC, and provide evidence supporting the evaluation of ADCs in NMIBC. PATIENT SUMMARY: We evaluated the potential role of targeted therapies that have been approved in the USA for advanced non-muscle-invasive bladder cancer (NMIBC) that has recurred after treatment with bacillus Calmette-Guérin (BCG). By assessing levels of specific genes and proteins linked to the targeted therapies, we demonstrate that there is rationale for further evaluation of these therapies in NMIBC.

Expression of Nectin-4 in Bladder Urothelial Carcinoma, in Morphologic Variants, and Nonurothelial Histotypes

The antibody-drug conjugate enfortumab-vedotin acts by targeting nectin-4, a protein that is nearly ubiquitously expressed in conventional urothelial cancer. However, expression of nectin-4 in morphologic variants of urothelial carcinoma and nonurothelial histotypes was unknown. Immunohistochemistry for nectin-4 using was performed on 169 patients including 83 with nonmuscle invasive bladder cancer and 86 patients with muscle invasive bladder cancer. Staining was scored for intensity (0 to 3) and extent (% positive cells) using the histological score system, where >15 was considered positive. Overall, 72/83 (87%) samples of nonmuscle invasive urothelial carcinoma were positive, including 29/30 (97%) noninvasive papillary urothelial carcinomas, 7/8 (87.5%) carcinomas in situ, 36/45 (80%) papillary urothelial carcinomas invading the lamina propria. Overall, 50/86 muscle invasive tumors were positive, including 15/22 (68.2%) urothelial carcinomas, 7/10 (70%) squamous cell carcinomas, 3/11 (28%) micropapillary tumors, 4/6 (66%) adenocarcinomas, 2/4 (50%) nested carcinomas, 5/8 (63%) plasmacytoid, 1/10 (10%) sarcomatoid carcinomas, and 0/15 (0%) small cell carcinomas. Whole transcriptome RNA sequencing revealed that compared with conventional urothelial carcinomas, most sarcomatoid carcinomas and all but 2 small cell carcinomas expressed very low levels of nectin-4 mRNA but expressed significant levels of either trop2 or ERBB2, which are the molecular targets of 2 other antibody-drug conjugates-sacituzumab gavitecan (trop2) or trastuzumab deruxtecan (ERBB2/HER2). In summary, our study demonstrates that there is heterogeneity of expression of nectin-4 in morphologic variants of urothelial cancer and nonurothelial histotypes, and suggests that testing expression of nectin-4 should be considered in morphologic variants or nonurothelial histotypes found to have lower expression.

Basal and Luminal Molecular Subtypes in Naturally-Occurring Canine Urothelial Carcinoma are Associated with Tumor Immune Signatures and Dog Breed

BACKGROUND: Improved therapies are needed for patients with invasive urothelial carcinoma (InvUC). Tailoring treatment to molecular subtypes holds promise, but requires further study, including studies in pre-clinical animal models. Naturally-occurring canine InvUC harbors luminal and basal subtypes, mimicking those observed in humans, and could offer a relevant model for the disease in people. OBJECTIVE: To further validate the canine InvUC model, clinical and tumor characteristics associated with luminal and basal subtypes in dogs were determined, with comparison to findings from humans. METHODS: RNA sequencing (RNA-seq) analyses were performed on 56 canine InvUC tissues and bladder mucosa from four normal dogs. Data were aligned to CanFam 3.1, and differentially expressed genes identified. Data were interrogated with panels of genes defining luminal and basal subtypes, immune signatures, and other tumor features. Subject and tumor characteristics, and outcome data were obtained from medical records. RESULTS: Twenty-nine tumors were classified as luminal and 27 tumors as basal subtype. Basal tumors were strongly associated with immune infiltration (OR 52.22, 95%CI 4.68–582.38, P = 0.001) and cancer progression signatures in RNA-seq analyses, more advanced clinical stage, and earlier onset of distant metastases in exploratory analyses (P = 0.0113). Luminal tumors were strongly associated with breeds at high risk for InvUC (OR 0.06, 95%CI 0.01 –0.37, P = 0.002), non-immune infiltrative signatures, and less advanced clinical stage. CONCLUSIONS: Dogs with InvUC could provide a valuable model for testing new treatment strategies in the context of molecular subtype and immune status, and the search for germline variants impacting InvUC onset and subtype.

Four versus 3 Cycles of Neoadjuvant Chemotherapy for Muscle-Invasive Bladder Cancer: Implications for Pathological Response and Survival

PURPOSE

The ideal number of neoadjuvant chemotherapy (NAC) cycles for muscle-invasive bladder cancer is uncertain with 3 to 4 representing the standard of care (SOC). We compared ypT0 rates and survival between patients receiving 4 versus 3 cycles of NAC with evaluation of chemotherapy-related toxicity for correlation with tumor chemosensitivity and pathological response.

MATERIALS AND METHODS

Patients receiving NAC followed by radical cystectomy for cT2-4N0M0 urothelial carcinoma from 2 institutions were included. Primary study groups included 4 cisplatin-based NAC cycles, 3 cisplatin-based NAC cycles, and nonSOC NAC (1-2 cycles or noncisplatin-based) to compare ypT0/≤ypT1 rates and survival. A cohort of patients not receiving NAC was included for pathological reference.

RESULTS

Of 693 total patients, 318 (45.9%) received NAC. ypT0 and ≤ypT1 rates were 42/157 (26.8%) and 86/157 (54.8%) for 4 cycles, 38/114 (33.3%) and 71/114 (62.3%) for 3 cycles, and 6/47 (12.8%) and 13/47 (27.7%) for nonSOC (p=0.03 and p <0.01, respectively). Pathological response appeared higher among patients receiving 3 cycles due to toxicity (ypT0: 29/77 [37.7%]; ≤ypT1: 51/77 [66.2%]) but did not reach statistical significance. Toxicities leading to treatment modifications were thrombocytopenia (32.1%), neutropenia (27.2%), renal insufficiency (22.2%), and constitutional symptoms (18.5%). NonSOC patients had lower Kaplan-Meier survival (cT2-cT4N0M0: log-rank p=0.07; cT2N0M0: log-rank p=0.02). There were no statistically significant differences in survival between 4 and 3 cycles (HR 1.00 [95% CI 0.57-1.74], p=0.99).

CONCLUSIONS

Patients completing 3 cycles of cisplatin-based NAC have similar pathologic response and short-term survival compared to 4 cycles. Further evaluation of patients experiencing toxicity as a potential marker of tumor chemosensitivity is needed.

Gender-specific Stratification of Survival Following Immune Checkpoint Inhibitor Therapy Based on Intratumoral Expression of a B cell Gene Signature

BACKGROUND

There is a great need to identify biomarkers that can accurately identify patients who will obtain the most clinical benefit from immune checkpoint inhibitor (ICI) therapy. While high intratumoral B cell gene expression correlated with an ICI response in melanoma, whether it adds predictive value in other cancers is unknown.

OBJECTIVE

To examine the relationship between B cell gene signature (BCGS) expression and overall survival (OS) following ICI treatment.

DESIGN, SETTING, AND PARTICIPANTS

A total of 348 patients with advanced urothelial carcinoma from the IMvigor 210 phase 2 clinical trial of atezolizumab and 406 patients with muscle-invasive bladder cancer from The Cancer Genome Atlas (TCGA) were included.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

We analyzed tumor RNA sequencing data of included patients to examine the relationships between a BCGS and clinical outcomes.

RESULTS AND LIMITATIONS

Tumors with high levels of B cell and CD8+ T cell gene signatures (BCGS/CD8TGS or B8T high/high) were associated with the longest OS of all B8T groups. Moreover, the B8T cell signature stratified patients whose tumors had a high tumor mutational burden or high programmed death ligand 1 (PD-L1) into subsets with differential OS outcomes. Whereas the B8T high/high tumors were associated with the best clinical outcomes in ICI-treated men, they were not associated with better OS in women. Conversely, women with B8T high/high tumors had the best clinical outcomes in non-ICI-treated muscle-invasive bladder cancer.

CONCLUSIONS

These data suggest that the B8T signature can enhance OS stratification in patients with advanced urothelial carcinoma who are treated with ICI therapy and that sex-specific differences in the tumor immune microenvironment may drive disparate outcomes.

PATIENT SUMMARY

We examined whether the presence of two immune cell gene signatures within tumor samples impact survival in patients with bladder cancer. High levels of both of these signatures (B cells and CD8+ T cells) associate with superior survival in patients who receive immune therapy.

Abstract CT121: A Phase II trial of guadecitabine (G) plus atezolizumab (A) in patients with metastatic urothelial carcinoma (UC) progressing after initial checkpoint inhibitor therapy

Introduction: We report the results of a phase II trial testing the hypothesis that adding the hypomethylating agent G to the PDL1 inhibitor A in patients with mUC who developed primary or acquired resistance to checkpoint blockade (CB) will overcome this resistance by (1) eliciting viral mimicry in the tumor tissue to potentiate and reinvigorate anti-tumor immunity, (2) epigenetic reprogramming of T lymphocytes to overcome exhaustion.

Methods: Pts with mUC resistant to CB accrued at 3 centers were treated with G 45mg/m2 daily days 1-5 every 6 wks and A 1200mg every 3 wks. After initial safety lead in with 6 patients, trial was designed to add 37 additional patients. The primary endpoint was ORR. Correlative analyses included analysis of peripheral blood T cells and tumor tissue collected at baseline and once during treatment.

Results: 21 pts were enrolled. 20 pts were evaluable for response. Best response was PD (16), SD (4). 10 patients progressed clinically prompting earlier than scheduled (12 wk) imaging. Four pts exhibited a “hyperprogression” phenotype exhibiting rapid acceleration of tumor growth rate starting with initiation of therapy. At presepcified interim analysis it was determined that the trial would not meet its primary endpoint and it closed early. Median PFS 2.6 mo, median OS 8 mo. The 4 patients with SD maintained that status for median 13 months (range 9-15 mo). Global DNA methylome and transcriptome profiles from pre- and post-treatment tumor samples revealed a lack of transposable element-induced viral mimicry activation, which correlated with minimal DNA demethylation being induced in the tumors. Of note, flow cytometry-based immune profiling of peripheral blood from patients suggests a correlation between increased progression-free survival (PFS) with 1) lower expression of DNAM-1 on mature NK cells and 2) lower expression of CD39 on CD8+ effector T cells at time of inclusion on the trial.

Conclusions: While no responses were seen, both prolonged SD and hyperprogression were seen. Further tissue and peripheral blood based analyses are ongoing to elucidate the biological determinates of this dichotomy.

Citation Format: Elizabeth R. Plimack, Kerry Campbell, Jean-Pierre J. Issa, Noah M. Hahn, David I. Quinn, Hyo Sik Jang, Galen Hostetter, Peter W. Nichols, Woonbok Chung, Jozef Madzo, Hitoshi Ohtani, Hui Shen, Toshinori Hinoue, Stephen B. Baylin, Peter A. Jones. A Phase II trial of guadecitabine (G) plus atezolizumab (A) in patients with metastatic urothelial carcinoma (UC) progressing after initial checkpoint inhibitor therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr CT121.

Abstract 2765: The indoleamine 2,3 dioxygenase-1 pathway drives intratumoral B cell maintenance

Immunotherapy has revolutionized cancer treatment by improving survival in many cancer subtypes. While tumor infiltrating B (TIL-B) cells correlate with response to immunotherapy in selected solid tumors, they portend resistance to BRAF inhibitors in BRAF mutant melanoma. Thus, the mechanisms underlying TIL-B cell function within the tumor microenvironment have remained elusive. Here, we discovered that inhibition of the indoleamine 2,3 dioxygenase-1 (IDO1) pathway with D-1-methyl-tryptophan (D-1MT) markedly decreases TIL-B cells in a preclinical model of melanoma. Single cell RNA sequencing (scRNAseq) of murine melanoma demonstrate TIL-B cells are heterogeneous: while some B cells express markers consistent with an immune stimulatory phenotype, others express markers consistent with immune inhibitory function. D-1MT decreased splenic B cells and bone marrow derived B cell precursors in tumor bearing mice, suggesting that IDO1 pathway inhibition impedes B cell maturation. In four distinct human cancer subtypes, intratumoral IDO1 expression consistently correlates with high expression of a pan-B cell gene signature. Further, analysis of scRNAseq data from a cohort of patients with melanoma revealed that most TIL-B cells express IDO1. In mice, D-1MT also decreases intratumoral myeloid derived suppressor cells (MDSCs), which are essential for maintenance of TIL-B cells. Surprisingly, we found that D-1MT enhanced anti-tumor effects of the BRAF inhibitor, vemurafenib, in a preclinical model of BRAF mutant melanoma, suggesting that targeting B cells in this setting may be beneficial. Together, our data reveal a novel paradigm for the IDO1 pathway in regulating TIL-B cells, and uncovered IDO1 as a potential targetable mechanism of resistance to BRAF inhibition in melanoma.

Citation Format: Burles Avner Johnson, Adam K. Aragaki, Donna M. Williams, Ophelia Rogers, Li Luo, Lingling Xian, Lionel Chia, Noah M. Hahn, Stephen Desiderio, Theodore S. Johnson, David J. McConkey, Linda M.S. Resar. The indoleamine 2,3 dioxygenase-1 pathway drives intratumoral B cell maintenance [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2765.

Abstract 970: Gender-specific stratification of survival following immune checkpoint inhibitor therapy based on intratumoral expression of a B cell gene signature

Despite intensive efforts there is still a great need to identify biomarkers that can accurately identify patients who will obtain the most clinical benefit from immune checkpoint inhibitor (ICI) therapy. High intratumoral CD8+ T cell gene signature (CD8TGS) expression, tumor mutational burden (TMB), and programmed death ligand 1 (PD-L1) expression all enrich for response to ICI treatment across multiple cancer subtypes. Although high intratumoral B cell gene expression also correlated with ICI response in melanoma, whether it adds predictive value in other cancers is unknown. We analyzed tumor RNA sequencing data from the IMvigor 210 phase 2 clinical trial of atezolizumab in patients with advanced urothelial carcinoma to examine potential relationships between B cell gene expression and clinical outcomes. Tumors with high levels of both signatures (BCGS/CD8TS or B8T high/high) had the highest overall survival (OS) of all B8T groups. Surprisingly, the subset of tumors with B8T high/low expression patterns were associated with the worst OS. Moreover, the B8T cell signature stratified patients with high TMB, or high PD-L1, into subsets with differential OS outcomes. Whereas the B8T high/high tumors were associated with the best clinical outcomes in ICI treated men, they were not associated with better OS in ICI treated women. Conversely, women with B8T high/high tumors had the best clinical outcomes in non-ICI treated muscle invasive bladder cancer. Collectively, these data suggest that the B8T signature can enhance OS stratification in patients with advanced urothelial carcinoma who were treated with ICI therapy, and that sex-specific differences in the tumor immune microenvironment may drive disparate outcomes.

Citation Format: Adam K. Aragaki, Jean Hoffman-Censits, Noah M. Hahn, David J. McConkey, Burles Avner Johnson. Gender-specific stratification of survival following immune checkpoint inhibitor therapy based on intratumoral expression of a B cell gene signature [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 970.

New and topics: enfortumab vedotin mechanisms of response and resistance in urothelial cancer - What do we understand so far?

Enfortumab vedotin (EV) was FDA approved in December 2019 for platinum- and checkpoint-refractory urothelial cancer based on an exceptional 44% response rate, and is currently approved for use after platinum and checkpoint inhibitor therapy. Enfortumab is an antibody-drug conjugate that targets Nectin-4, which is widely expressed in urothelial cancer. Despite this ample target, clinical benefit is not achieved by all patients, and mechanisms of treatment resistance are undescribed. Herein we summarize what is known to date regarding coorelative findings and subgroup analysis and EV response, including novel biopsy data in patients with tumor progression post EV.

PrE0807: A phase Ib feasibility trial of neoadjuvant nivolumab (N) without or with lirilumab (L) in cisplatin-ineligible patients (pts) with muscle-invasive bladder cancer (MIBC)

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Background: Neoadjuvant cisplatin-based chemotherapy (CT) prior to radical cystectomy (RC) improves overall survival (OS) in MIBC, but about half of pts are cisplatin-unfit or refuse it. Neoadjuvant immune checkpoint inhibitors can induce high pathologic complete response rate (ypT0N0). The combination of anti-PD-1 (N) and anti-KIR (L) is hypothesized to be safe and have significant activity based on the complementary and possibly synergistic roles in regulating adaptive and innate immune response in MIBC. Methods: This is a phase Ib multi-institutional trial in pts with localized MIBC treated with 2 neoadjuvant doses (4 weeks apart) of N alone (480 mg) in cohort 1 or N (480 mg) + L (240 mg) in cohort 2 prior to RC without adjuvant therapy (NCT03532451). Cohorts were enrolled sequentially and were not randomized. Key eligibility criteria included stage cT2-4aN0-1M0, ≥20% tumor content at TURBT and cisplatin-ineligibility (Galsky criteria) or refusal. Primary endpoint was safety manifested as rate of ≥G3 treatment related adverse events (TRAE) assessed in each cohort with CTCAE v5.0. Key secondary endpoints included the % of pts who had RC > 6 weeks after last neoadjuvant dose due to TRAE, CD8+ T cell density at RC, ypT0N0 and < ypT2N0 rates, CD8+ T cell density change between TURBT and RC, recurrence-free survival (RFS) and biomarkers in tumor tissue, blood and urine. Results: Among 43 pts enrolled (13 cohort 1, 30 cohort 2), median age was 75 (51-89), 67% were men, all had PS ECOG 0-1. Pts were cisplatin-ineligible due to impaired renal function (47%) and hearing loss (37%), while 14 % refused cisplatin. At baseline, 37 pts had cT2 stage, 2 had cN1 and 3 cNx. In cohort 1 and 2, 13 and 29 pts, respectively, completed intended neoadjuvant treatment, and 41/43 underwent RC (12/13 cohort 1, 29/30 cohort 2). One pt progressed to metastatic disease prior to RC (cohort 1) and 1 withdrew consent prior to being treated (cohort 2). Additionally, 1 patient was found to have cervical cancer at RC. Median time from last neoadjuvant dose to RC was 27 (95%CI: 24-29) days. There was no RC delayed > 6 weeks from treatment completion due to TRAE. G3 TRAEs occurred in 0% with N and 6.7% (90%CI 1.2-19.5%) in N+L (1: arthralgia, 1: gout, 2: hip pain) that all resolved. No G4/5 TRAEs occurred. Of 40 pts with MIBC and RC, ypT0N0 rates for N and N+L were 8% and 18%, while < ypT2N0 rates were 17% and 29%, respectively. Data on RFS and OS, and biomarker data were not yet mature. Conclusions: Neoadjuvant N alone and N+L combination prior to RC were safe, feasible and well tolerated in cisplatin-ineligible pts with MIBC, but ypT0N0 rates were unexpectedly low, especially with N alone. Two phase 3 trials (NCT03661320; NCT04209114) are evaluating the peri-operative role of N + chemotherapy +/- Linrodostat in cisplatin-fit and N +/- Bempeg in cisplatin unfit patients and are also assessing biomarkers. Clinical trial information: NCT03532451.

First-line pembrolizumab (pembro) in cisplatin-ineligible patients with advanced urothelial cancer (UC): Response and survival results up to five years from the KEYNOTE-052 phase 2 study

4508

Background: Pembro was approvedfor cisplatin-ineligible patients with untreated advanced UC based on initial results of the phase 2 KEYNOTE-052 study (NCT02335424), which showed an ORR of 29%. Updated results after up to 5 years of follow-up are presented. Methods: KEYNOTE-052 is a single-arm, multi-site, open-label trial. Patients had advanced or metastatic UC, were cisplatin ineligible (criteria: ECOG PS 2, CrCl ≥30 to ̃60 mL/min, grade ≥2 peripheral neuropathy/hearing loss, NYHA class III heart failure), and had not previously received chemotherapy for advanced/metastatic disease. Patients received pembro 200 mg IV Q3W until progression, unacceptable toxicity, withdrawal, or 24 mo of therapy, whichever occurred first. PD-L1 status was determined by combined positive score (CPS, number of PD-L1–staining cells [tumor cells, lymphocytes, macrophages] divided by the total number of viable tumor cells, multiplied by 100); PD-L1–positive was CPS ≥10. The primary end point was confirmed ORR (RECIST v1.1, independent central review). Key secondary end points were duration of response (DOR), OS, and safety. Results: Among 370 enrolled patients, median age was 74 y, 315 (85.1%) had visceral disease, and 43 (11.6%) completed 24 mo of therapy. Median time from enrollment to data cutoff (Sep 26, 2020) was 56.3 mo (range, 51.2-65.3) for all patients and 56.0 mo (range, 51.4-65.2) for the 110 patients (29.7%) with CPS ≥10. Confirmed ORR for all patients was 28.9% (95% CI, 24.3-33.8); complete response, 9.5% (n=35); partial response, 19.5% (n=72). Median DOR was 33.4 mo (range, 1.4+ to 60.7+); 44.8% and 39.4% of patients had DOR ≥36 and ≥48 mo, (Kaplan-Meier estimates). Median OS was 11.3 mo (95% CI, 9.7-13.1); 24- and 36-mo OS rates were 31.5% and 22.1%. Patients with CPS ≥10 had better outcomes than patients with CPS <10 (Table). Treatment-related adverse events (AEs) occurred in 67.3% of patients; 21.1% of treatment-related AEs were grade ≥3, including 1 death (myositis). Conclusions: After up to 5 y of follow-up, pembro continued to elicit clinically meaningful, durable antitumor activity in cisplatin-ineligible patients with advanced UC. These effects were more pronounced in patients with CPS ≥10. Clinical trial information: NCT02335424. [Table: see text]

EA8185: Phase 2 study of bladder-sparing chemoradiation (chemoRT) with durvalumab in clinical stage III, node positive urothelial carcinoma (INSPIRE)—An ECOG-ACRIN and NRG Collaboration

TPS4590

Background: Patients [pts] withlymph node positive (LN+), non-metastatic bladder cancer (BC) have a better prognosis than those with metastatic (M1) disease. However, this population is under-represented in advanced bladder trials and ineligible for bladder-sparing trials. Therefore, there have been no larger prospective trials establishing the standard of care in LN+ BC. Given the promise of immunotherapy in advanced BC and potential synergy between immunotherapy and radiation, INSPIRE was designed to determine the role of concurrent and adjuvant durvalumab (durva) in this patient population when treated with induction chemotherapy (IC) followed by concurrent chemoRT. Methods: This is a randomized phase II study that is enrolling BC pts with stage III [N1-2 M0], pure or mixed urothelial cancer. Pts must have received ≥3 cycles of IC [either before or after registration, prior to randomization] without progression. LN+ is defined as radiologically LN ≥1.0 cm in short axis, with or without biopsy prior to IC. As long as pts do not progress on induction chemotherapy, they will be randomized to chemoRT+/- durva using 5 stratification factors (Simon Pocock minimization method) a) IC prior vs. post registration b) cisplatin vs non-cisplatin regimen during RT c) LN size d) response to IC e) extent of TURBT. Pts on the chemoRT+durva arm will get chemotherapy per physician choice + IMRT + 3 x doses of Q3wk durva for 6.5-8 wks, whereas those on the control arm will get chemoRT alone. The primary end point is clinical complete response [CR], defined as no radiologically measurable disease in the LNs and negative cystoscopy and bladder biopsy 8-10 weeks post-chemoRT +/- durva. Pts on the chemoRT + durva arm who have a CR or clinical benefit ( > T0 and ≤T2 in bladder per cystoscopy, biopsy + CR/PR/SD in LN by imaging) will get adjuvant Q4wk durva for 9 doses, while those on the chemoRT arm will undergo observation. Secondary end points include OS, PFS, bladder-intact event-free survival, rate of toxicity and salvage cystectomy. This study is designed to detect an improvement of 25% in clinical CR between both arms (37.5% to 62.5%). A total accrual of 114 pts (in order to enroll 92 evaluable pts) will provide 81% power to detect this difference using a Fisher’s exact test (assuming 10% drop out + anticipating that 20% chemotherapy-naïve pts will progress post IC). We are banking blood and primary tumor tissue pre- and post-chemoRT in both groups. The study was activated in August 2020 and accrual is ongoing. INSPIRE is the first prospective study designed for only LN+ BC and will define both short-term and long-term outcomes for bladder sparing in this patient population and has the potential to define a new treatment strategy for stage III BC. Clinical trial information: NCT04216290.

INTACT (S/N1806) phase III randomized trial of concurrent chemoradiotherapy with or without atezolizumab in localized muscle-invasive bladder cancer: Safety update on first 73 patients

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Background: Trimodality therapy (TMT) with maximal TURBT followed by chemoradiation(CRT) is a standard of care for select patients with muscle invasive bladder cancer (MIBC). This trial evaluates the activity of atezolizumab (atezo) in MIBC in combination with TMT. This trial was designed with pre-specified safety analyses of the first 80 patients (40 in each arm). At the time of SWOG fall 2020 DSMC report deadline we had enrolled 84 patients but data on only 73 patients were available. The same data are being submitted to ASCO GU meeting. Methods: This trial is testing atezo every 3 weeks for 6 months given concurrently and adjuvantly with CRT vs. CRT alone in 475 patients with MIBC T2-T4aN0M0 disease. Patients are stratified based on PS; T2 vs T3 or T4; choice of chemotherapy; and radiation field (bladder only vs small pelvis). Patients undergo biopsy 3 months after finishing CRT to assess treatment response. Patients are followed for 5 years for recurrence or survival. This trial was not preceded by a phase I study but was designed with a safety run in of 80 patients. Study team agreed on the study design based on available data from other tumor types and initial experience from investigators running smaller similar trials. It was pre-specified that if we observe more than 25% patients having grade 3-5 colitis or cystitis in the atezo arm or any other toxicity which is deemed clinically significant and related to atezo, the trial investigators and DSMC would consider stopping further enrollment. Results: 36 patients were enrolled on the TMT alone arm and 37 patients on the TMT + atezo arm. No grade 3 or higher colitis was reported in the atezo arm. Only one patient had treatment related grade 3 radiation cystitis which was diagnosed after finishing atezo treatment. No steroids were given. Overall 23 grade 3 or higher toxicity events were reported in the atezo arm vs 11 in non- atezo arm. Most common toxicity was hematological which was considered non-immune related. None of the grade 3 or higher toxicities were considered to be immune related by the treating investigator. Conclusions: There is no evidence of increased immune related grade 3-5 AEs.DSMC has recommended to continue enrollment. Adverse Events with No Entries for Grades 3 to 5 Have Been Suppressed Clinical trial information: NCT03775265 . [Table: see text]

Sapanisertib, a dual mTORC1/2 inhibitor, for TSC1- or TSC2-mutated metastatic urothelial carcinoma (mUC)

431

Background: A mammalian target of rapamycin (mTOR) inhibitor, everolimus, showed activity in patients with metastatic urothelial carcinoma (mUC) including an exceptional objective response in a patient with a deleterious TSC1 mutation. Sapanisertib is a potent inhibitor of mTOR complex 1 and 2. Here, we present the data from a phase II study of sapanisertib in patients with TSC1- or TSC2-mutated mUC. Methods: Eligible mUC patients with a TSC1 or TSC2 mutation received sapanisertib 3mg po daily on days 1 through 28 every 28 days. Primary endpoint was the overall response rate. Tumor samples were submitted for central confirmation of the mutation. A prescreening test for TSC1/2 mutation was available at a central lab for those with unknown mutational status. Results: Tumor samples from 41 patients were submitted for either prescreening (n=24) or confirmation (n=17). Of 24 prescreening patients, 4 (16%) had TSC1 mutation; 2 (8%) had TSC2 mutations. Of 17 confirmatory testing, 16 were confirmed by the central lab. Of 23 potentially eligible patients with a TSC1 or TSC2 mutation, 17 (14 TSC1 and 3 TSC2) were enrolled. Baseline characteristics of these 17 patients are shown. Four patients with TSC1- mutated mUC were deemed non-evaluable for response; two withdrew consent before starting sapanisertib to pursue an alternative therapy, and the other two withdrew consent with an adverse event before completing the first cycle. Of 13 evaluable patients, no objective response was observed. Although 4 patients had stable disease (SD) at their first restaging scan, none were confirmed to have SD with a subsequent scan. Median overall survival is 3.4 months. Four patients withdrew consent due to adverse event. Most common adverse events were hyperglycemia (80%), Cr elevation (53%) and AST increased (46.7%). No treatment-related death was observed. Conclusions: Sapanisertib did not result in any objective response in 13 patients with TSC1- or TSC2-mutated mUC. Given the lack of clinical activity, and problems with tolerance of sapanisertib, the trial was terminated early for futility. Future studies of an mTOR inhibitor or other targeted agent in the mTOR pathway should examine molecular alterations beyond TSC1 or TSC2. Clinical trial information: NCT03047213 . [Table: see text]

Patient, caregiver, and provider reported risk-benefit acceptance thresholds in non-muscle invasive bladder cancer (NMIBC) trial designs

424

Background: FDA guidelines for NMIBC clinical trial design have stimulated a marked increase in NMIBC trial conduct. However, NMIBC patient (PT) input to define acceptable treatment toxicity thresholds and clinical measures most meaningful to NMIBC PTS has been lacking. We conducted a survey to investigate treatment side effect tolerance levels, respondent-ranked clinical relevance of various trial efficacy measures, and differences in responses between PTS, caregivers (CG), and healthcare providers. Methods: In 8/2018, an NMIBC Patient-Driven Endpoints working group was formed at the Bladder Cancer Advocacy Network (BCAN) Think Tank meeting. Through iterative focus groups, a 21-question survey composed of 4 domains (demographics, treatment history, acceptable toxicity thresholds, and clinical benefit metrics) was designed. The BCAN Patient Survey Network and other social media platforms were utilized to distribute and publicize the survey. A unique IP address was required to eliminate duplicate respondents. Categorical and ordinal variables were reported as frequencies with 95% confidence intervals. Continuous variables were reported as medians with ranges. Frequency differences in specific variables of interest according to respondent roles were assessed by Chi-square testing with significance set at p < .05. Results: From 7/18-8/30/20, 845 survey responses were recorded. Key demographics included: 647 (76.7%) PTS, 77 CG (9.1%), 67 urologists (UROL) (7.9%), 35 medical oncologists (ONC) (4.1%), 59.8% male, 85.0% Caucasian non-Hispanic, median age 64.0 years, and 62.7% with NMIBC at diagnosis. Any reversible toxicity was deemed acceptable in 68.8% of PT, 61.0% of CG, 62.7% of UROL, and 54.3% of ONC respondents p = 0.09. Any permanent toxicity was deemed acceptable by 15.6% of PT, 11.7% of CG, 16.4% of UROL, and 20.0% of ONC respondents p = 0.54. Differences in acceptance of individual treatment related toxicities according to roles were observed p < .05 and will be presented. Mean rank order of potential clinical trial endpoints with a rank of 1 for most clinically meaningful benefit to 5 for least meaningful were 1.96 for avoidance of cystectomy, 2.13 for prevention of muscle invasion, 2.87 for 24-month recurrence free survival (RFS), 3.55 for 12-month RFS, and 3.97 for complete response rate with little variation according to respondent roles. Conclusions: Threshold levels for global reversible and permanent treatment toxicity rates were similar across respondent roles. Complete response was consistently ranked lowest in clinical relevance among all respondent roles. These survey results provide important patient and provider benchmarks for acceptable toxicity thresholds within future NMIBC trial designs and suggest an increased emphasis on bladder preservation and durability of response in evaluating the merits of new NMIBC therapies.

EA8185: Phase II study of bladder-sparing chemoradiation (chemoRT) with durvalumab in clinical stage III, node-positive urothelial carcinoma (INSPIRE), ECOG-ACRIN/nrg collaboration

TPS500

Background: Patients [pts] withlymph node positive (LN+), non-metastatic bladder cancer (BC) have a better prognosis than those with metastatic (M1) disease. However, this population is under-represented in advanced bladder trials and ineligible for bladder-sparing trials. Therefore, there have been no larger prospective trials establishing the standard of care in LN+ BC. Given the promise of immunotherapy in advanced BC and potential synergy between immunotherapy and radiation, INSPIRE was designed to determine the role of concurrent and adjuvant durvalumab (durva) in this patient population when treated with induction chemotherapy (IC) followed by concurrent chemoRT. Methods: This is a randomized phase II study that is enrolling BC pts with stage III (N1-2 M0), pure or mixed urothelial cancer. Pts must have received ≥3 cycles of IC [either before or after registration, prior to randomization] without progression. LN+ is defined as radiologically LN ≥1.0 cm in short axis, with or without biopsy prior to IC. As long as pts do not progress on induction chemotherapy, they will be randomized to chemoRT+/- durva using 5 stratification factors (Simon Pocock minimization method) a) IC prior vs. post registration b) cisplatin vs non-cisplatin regimen during RT c) LN size d) response to IC e) extent of TURBT. Pts on the chemoRT+durva arm will get chemotherapy per physician choice + IMRT + 3 x doses of Q3wk durva for 6.5-8 wks, whereas those on the control arm will get chemoRT alone. The primary end point is clinical complete response [CR], defined as no radiologically measurable disease in the LNs and negative cystoscopy and bladder biopsy 8-10 weeks post-chemoRT +/- durva. Pts on the chemoRT + durva arm who have a CR or clinical benefit (>T0 and ≤T2 in bladder per cystoscopy, biopsy + CR/PR/SD in LN by imaging) will get adjuvant Q4wk durva for 9 doses, while those on the chemoRT arm will undergo observation. Secondary end points include OS, PFS, bladder-intact event-free survival, rate of toxicity and salvage cystectomy. This study is designed to detect an improvement of 25% in clinical CR between both arms (37.5% to 62.5%). A total accrual of 114 pts (in order to enroll 92 evaluable pts) will provide 81% power to detect this difference using a Fisher’s exact test (assuming 10% drop out + anticipating that 20% chemotherapy-naïve pts will progress post IC). We are banking blood and primary tumor tissue pre- and post-chemoRT in both groups. The study was activated in August 2020 and accrual is ongoing. INSPIRE is the first prospective study designed for only LN+ BC and will define both short-term and long-term outcomes for bladder sparing in this patient population and has the potential to define a new treatment strategy for stage III BC. Clinical trial information: NCT04216290.

Urothelial Carcinoma In Situ of the Bladder: Correlation of CK20 Expression With Adaptive Immune Resistance, Response to BCG Therapy, and Clinical Outcome

Immunohistochemical stains have been suggested to aid in diagnostically challenging cases of urothelial carcinoma in-situ (CIS). Although full thickness immunostaining for CK20 is supportive of CIS, a subset of CIS cases is CK20(-), the clinical significance of which was unknown. This study included 43 patients with primary diagnosis of bladder CIS including 32 with only CIS, 5 with CIS and separate noninvasive high-grade papillary urothelial carcinoma, and 6 with CIS and separate high-grade urothelial carcinoma with lamina propria invasion. Digital morphometric image analysis showed that the average nuclear areas of enlarged nuclei were similar in CK20(+) and CK20(-) CIS (26.9 vs. 24.5 µM2; P=0.31). Average Ki67 index for CK20(+) CIS was higher than CK20(-) CIS (31.1% vs. 18.3%; P=0.03). Patients with CK20(+) CIS [28 (65%)] and patients with CK20(-) CIS [15 (35%)] had the same rates of Bacillus Calmete-Guerin (BCG) failure but patients with CK20(-) CIS had higher stage progression [3 CK20(+) (11%) vs. 6 CK20(-) (40%); P=0.02]. Given recent approval of immune checkpoint inhibitors in patients with CIS refractory to BCG, programmed death ligand-1 expression and colocalization with CD8(+) lymphocytes was investigated as signature of adaptive immune response and was seen in 8 patients regardless of CK20 status and exclusively among patients who failed BCG. Our results confirm that negative CK20 IHC does not exclude CIS and that those patients have similar clinical outcomes as patients with CK20(+) CIS. Programmed death ligand-1 and CD8 colocalization seen among patients who failed BCG therapy is an easy assay to perform to identify patients who could potentially benefit from combined BCG therapy and immune checkpoint inhibition.

Phase I, Pharmacogenomic, Drug Interaction Study of Sorafenib and Bevacizumab in Combination with Paclitaxel in Patients with Advanced Refractory Solid Tumors

VEGF blockade does not uniformly result in clinical benefit. We evaluated safety, dose-limiting toxicities (DLT), recommended phase II dose (RP2D), antitumor efficacy, and exploratory biomarkers including pharmacogenomics and pharmacokinetics with sorafenib, bevacizumab, and paclitaxel in patients with refractory cancers. The study had a "3 + 3" design, using paclitaxel 80 mg/m² every week for 3 weeks, in every 4 week cycles, bevacizumab 5 mg/kg every 2 weeks, and sorafenib 200 or 400 mg twice a day, 5 or 7 days/week (5/7, 7/7). The MTD cohort was expanded. Twenty-seven patients enrolled in 3 cohorts: sorafenib 200 mg twice a day 5/7, 200 mg twice a day 7/7, and 400 mg twice a day 5/7. DLTs were grade 3 neutropenia >7 days (cohort 1, 1), grade 3 hypertension (cohort 2, 1), grade 3 hand-foot skin reaction (HFSR; cohort 3, 2). MTD was sorafenib 200 mg twice a day 7/7. Six DLTs occurred in cohort 2 expansion: grade 3 HFSR (2), grade 2 HFSR with sorafenib delay >7 days (2), grade 4 cerebrovascular accident (1), grade 3 neutropenia >7 days (1). RP2D was sorafenib 200 mg twice a day 5/7. Most patients (62%) dose reduced sorafenib to 200 mg daily 5/7 after a median 3 (range, 2-17) cycles. Response rates were 48% overall (27) and 64% for ovarian cancers (14). VEGF-A-1154AA and -7TT recessive homozygous genotypes conferred worse overall survival versus alternative genotypes (7 vs. 22 months). Intermittent, low-dose sorafenib (200 mg twice a day 5/7) combined with bevacizumab and paclitaxel was tolerable and had high antitumor efficacy in patients with refractory cancer (NCT00572078).

A randomized phase 2 trial of pembrolizumab versus pembrolizumab and acalabrutinib in patients with platinum-resistant metastatic urothelial cancer

Background

Inhibition of the programmed cell death protein 1 (PD‐1) pathway has demonstrated clinical benefit in metastatic urothelial cancer (mUC); however, response rates of 15% to 26% highlight the need for more effective therapies. Bruton tyrosine kinase (BTK) inhibition may suppress myeloid‐derived suppressor cells (MDSCs) and improve T‐cell activation.

Methods

The Randomized Phase 2 Trial of Acalabrutinib and Pembrolizumab Immunotherapy Dual Checkpoint Inhibition in Platinum‐Resistant Metastatic Urothelial Carcinoma (RAPID CHECK; also known as ACE‐ST‐005) was a randomized phase 2 trial evaluating the PD‐1 inhibitor pembrolizumab with or without the BTK inhibitor acalabrutinib for patients with platinum‐refractory mUC. The primary objectives were safety and objective response rates (ORRs) according to the Response Evaluation Criteria in Solid Tumors, version 1.1. Secondary endpoints included progression‐free survival (PFS) and overall survival (OS). Immune profiling was performed to analyze circulating monocytic MDSCs and T cells.

Results

Seventy‐five patients were treated with pembrolizumab (n = 35) or pembrolizumab plus acalabrutinib (n = 40). The ORR was 26% with pembrolizumab (9% with a complete response [CR]) and 20% with pembrolizumab plus acalabrutinib (10% with a CR). The grade 3/4 adverse events (AEs) that occurred in ≥15% of the patients were anemia (20%) with pembrolizumab and fatigue (23%), increased alanine aminotransferase (23%), urinary tract infections (18%), and anemia (18%) with pembrolizumab plus acalabrutinib. One patient treated with pembrolizumab plus acalabrutinib had high MDSCs at the baseline, which significantly decreased at week 7. Overall, MDSCs were not correlated with a clinical response, but some subsets of CD8+ T cells did increase during the combination treatment.

Conclusions

Both treatments were generally well tolerated, although serious AE rates were higher with the combination. Acalabrutinib plus pembrolizumab did not improve the ORR, PFS, or OS in comparison with pembrolizumab alone in mUC. Baseline and on‐treatment peripheral monocytic MDSCs were not different in the treatment cohorts. Proliferating CD8+ T‐cell subsets increased during treatment, particularly in the combination cohort. Ongoing studies are correlating these peripheral immunome findings with tissue‐based immune cell infiltration.

In this randomized phase 2 study of metastatic urothelial cancer, a combination of pembrolizumab and a Bruton tyrosine kinase inhibitor (acalabrutinib) does not improve clinical outcomes in comparison with pembrolizumab alone. Comprehensive flow cytometry is used to evaluate circulating immune cells during treatment.

Abstract IA20: Intravesical versus systemic therapy: Win, lose, or draw—the future is now for multidisciplinary NMIBC drug development

In recent years, we have witnessed an explosion in both therapeutic drug development and our understanding of the key biologic drivers and targets in bladder cancer. While new drug approvals have thus far been confined to metastatic patients, several promising agents have fully accrued key FDA registration studies in the BCG-unresponsive non-muscle invasive bladder cancer (NMIBC) population. Initial early-response data in the carcinoma in situ (CIS) populations demonstrate clear signals of activity with long-term follow-up ongoing to assess response durability. Agents administered by either intravesical or systemic routes are among those being assessed. While urologists, medical oncologists, and radiation oncologists have long worked together in the care of muscle-invasive bladder cancer (MIBC) and metastatic bladder cancer patients, an established template of multidisciplinary collaboration in the care of NMIBC patients is lacking. This unknown frontier creates both challenges and immense opportunities. True lasting, impactful progress rarely happens in isolation. This session will utilize data and example cases to illustrate specialty-specific skills and perceptions that define us, must be acknowledged for the biases they create, and ultimately should be embraced as a vehicle to establish functional and collaborative multidisciplinary drug development and clinical care models for NIMIBC patients.

Citation Format: Noah M. Hahn. Intravesical versus systemic therapy: Win, lose, or draw—the future is now for multidisciplinary NMIBC drug development [abstract]. In: Proceedings of the AACR Special Conference on Bladder Cancer: Transforming the Field; 2019 May 18-21; Denver, CO. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(15_Suppl):Abstract nr IA20.

Abstract PR05: Similarities in molecular subtypes and subtype immune patterns between naturally occurring canine and human invasive bladder cancer

Relevant animal models are needed to study treatment strategies related to the molecular subtypes of bladder cancer and the immune response between these subtypes. The purpose of the study was to characterize the molecular subtypes and immune features in naturally occurring canine invasive urothelial carcinoma (InvUC). Canine InvUC is already known to mimic the human condition in pathologic features, metastatic behavior, and chemotherapy response. Molecular subtyping could further increase the utilization of the canine model. RNA-seq data from canine InvUC (n=56) and normal canine bladder mucosa (n=4) were analyzed using Strand NGS (Strand Genomics, San Francisco, CA). Data were normalized (DESeq, TMM), and DEGs selected (2FC, pcorr &lt;0.05) using DESeq2 and edge R, respectively. Following unsupervised clustering that identified two groups of tumors, supervised clustering was performed in which the data were interrogated using a panel of genes known to classify human bladder cancer subtypes (TCGA), as well as multiple gene panels that classify human bladder cancer as immune hot (infiltrated) or immune cold (noninfiltrated, immune-suppressor features). Infiltrating immune cells were observed in histologic sections with CD3 immunohistochemistry. Distinct luminal (n=28) and basal (n=28) subtypes were identified in the canine InvUC samples, with subclassifications emerging in both subtypes. There was anticipated heterogeneity between the samples, but of the 28 basal tumors, all had hot immune features, with 10 being exceptionally hot. Of the luminal tumors, 22 of 28 were notably immune cold. In conclusion, canine InvUC mimics human invasive bladder cancer in regard to molecular subtypes and immune patterns within subtypes. This expands the value of the canine bladder cancer model and offers opportunities to study strategies for individualized therapy and to develop strategies to enhance the tumor immune environment in order to improve treatment outcomes. Support: NIH/NCI P30CA023168 Supp (Knapp, Ratliff).

This abstract is also being presented as Poster A26.

Citation Format: Deepika Dhawan, Breann C. Sommer, José A. Ramos-Vara, Noah M. Hahn, Deborah W. Knapp. Similarities in molecular subtypes and subtype immune patterns between naturally occurring canine and human invasive bladder cancer [abstract]. In: Proceedings of the AACR Special Conference on Bladder Cancer: Transforming the Field; 2019 May 18-21; Denver, CO. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(15_Suppl):Abstract nr PR05.

Long-Term Outcomes in KEYNOTE-052: Phase II Study Investigating First-Line Pembrolizumab in Cisplatin-Ineligible Patients With Locally Advanced or Metastatic Urothelial Cancer

PURPOSE

The phase II single-arm KEYNOTE-052 study evaluated the efficacy and safety of first-line pembrolizumab for patients with locally advanced or metastatic cisplatin-ineligible urothelial carcinoma (UC).

PATIENTS AND METHODS

Three hundred seventy patients received pembrolizumab 200 mg intravenously every 3 weeks for up to 24 months. Positive tumor programmed death ligand 1 (PD-L1) expression was defined as combined positive score (CPS) ≥ 10. Response was assessed by independent central review every 9 weeks per RECIST v1.1. The primary end point was objective response rate (ORR).

RESULTS

At data cutoff (September 26, 2018), the minimum follow-up was 2 years since the last patient enrolled. ORR was 28.6% (95% CI, 24.1% to 33.5%); 33 patients (8.9%) and 73 patients (19.7%) achieved complete and partial response, respectively. The median duration of response was 30.1 months (95% CI, 18.1 months to not reached [NR]); responses lasted ≥ 12 and ≥ 24 months in 67% and 52% of patients, respectively. Forty patients with complete or partial response completed 2 years of study treatment, and 32 had ongoing response at completion. Median overall survival (OS) was 11.3 months (95% CI, 9.7 to 13.1 months), and 12- and 24-month OS rates were 46.9% and 31.2%, respectively. In patients with CPS ≥ 10, ORR was 47.3% (95% CI, 37.7% to 57.0%) and median OS was 18.5 months (95% CI, 12.2 to 28.5 months). In patients with lymph node-only disease, ORR was 49.0% (95% CI, 34.8% to 63.4%), and median OS was 27.0 months (12.4 months to NR). There were no new safety signals.

CONCLUSION

First-line pembrolizumab confers meaningful and durable clinical response in cisplatin-ineligible patients with advanced UC and is associated with prolonged OS, particularly with PD-L1 CPS ≥ 10 and lymph node-only disease.

A phase II, randomized study of nivolumab (NIVO), NIVO plus linrodostat mesylate, or NIVO plus intravesical bacillus Calmette-Guerin (BCG) in BCG-unresponsive, high-risk, nonmuscle invasive bladder cancer (NMIBC): CheckMate 9UT

TPS5090

Background: Immune checkpoint inhibitors, including NIVO (anti–PD-1), have demonstrated favorable tolerability and efficacy profiles, ushering in a new treatment (tx) paradigm for advanced bladder cancer (advBC). However, an unmet need exists for new effective tx options in earlier stages of disease, specifically for patients (pts) with BCG-unresponsive, high-risk NMIBC. Increased IDO and PD-L1 expression in NMIBC tumors (Inman, et al. Cancer 2007; Hudolin, et al. Anticancer Res 2017), support the combination of anti–PD-1 and IDO1 inhibition in NMIBC. Linrodostat mesylate, a selective, potent, once-daily IDO1 inhibitor, has demonstrated clinical activity in combination with NIVO in pts with immunotherapy-naive advBC who received ≥ 1 prior line of therapy (objective response rate, 37%; Tabernero, et al. J Clin Oncol 2018;36(suppl) [abstr 4512]). Furthermore, high levels of PD-L1 expression have been reported in patients not responding to BCG tx. These findings provide a rationale for investigation of NIVO ± linrodostat ± intravesical BCG therapy in BCG-unresponsive high-risk NMIBC. Here we describe a phase 2, randomized, open-label study assessing the safety and efficacy of NIVO ± linrodostat ± intravesical BCG in pts with BCG-unresponsive, high-risk NMIBC (NCT03519256). Methods: Pts aged ≥ 18 years with BCG-unresponsive (per February 2018 FDA guidance), high-risk NMIBC, defined as carcinoma-in-situ (CIS) with or without papillary component, any T1, or Ta high-grade lesions, will be enrolled. Pts must have urothelial carcinoma as the predominant histological component ( > 50%). Key exclusion criteria include locally advanced or metastatic BC, upper urinary tract disease within 2 years, prostatic urethral disease within 1 year, and prior immunotherapy. Using a novel adaptive-type design, pts will be randomized to 1 of 4 tx arms with NIVO ± linrodostat ± BCG. Primary endpoints include proportion of pts with CIS with complete response (CR) and duration of CR in pts with CIS. Secondary endpoints are progression-free survival and safety. This global study in 14 countries is underway, with a target enrollment of 436 pts. Clinical trial information: NCT03519256 .