PDIGREE: An adaptive phase III trial of PD-inhibitor nivolumab and ipilimumab (IPI-NIVO) with VEGF TKI cabozantinib (CABO) in metastatic untreated renal cell cancer (Alliance A031704)

TPS366

Background: First-line treatment of mRCC has rapidly changed to include IPI-NIVO or CABO, with clinical benefit of each based on the Checkmate 214 and CABOSUN (A031203) trials. Combination immunotherapy with VEGF therapies has shown benefit over sunitinib in the JAVELIN 101 and KEYNOTE 426 trials. It is yet unclear which patients (pts) benefit most from combination immunotherapy-VEGF inhibitors, and the optimal sequence of drugs. Methods: In an adaptive, randomized, multicenter phase III trial (Alliance A031704, PDIGREE), pts start treatment with induction IPI 1 mg/kg and NIVO 3 mg/kg intravenously (IV) once every 3 weeks. Key inclusion criteria include clear cell mRCC, International Metastatic RCC Database Consortium (IMDC) intermediate or poor risk, Karnofsky performance status >70, and no prior treatments for mRCC. Based on 3-month radiographic assessment (after completing IPI-NIVO combination), pts with complete responses (CR) undergo maintenance NIVO 480 mg IV every 4 weeks; pts with progression of disease (PD) switch to CABO 60 mg oral daily; pts with non-CR/non-PD are randomized to NIVO 480 mg IV every 4 weeks versus NIVO 480 mg IV every 4 weeks with CABO 40 mg oral daily. Randomization is stratified by IMDC risk criteria and presence of bone metastases. The primary endpoint of the study is overall survival (OS). We hypothesize that 3-year OS will improve to 70% for NIVO-CABO compared to 60% for NIVO alone; to achieve 85% power with a two-sided alpha of 0.05 and exponential distribution, 696 patients will be randomized. Accounting for 30% patients with either CR or PD, and 5% dropout from toxicity, up to 1046 pts will be enrolled. Key secondary endpoints include progression-free survival, 12-month CR rate, overall response rate based on RECIST 1.1 and iRECIST criteria, and toxicity profiles. Quality of life will be assessed based on the FKSI-19, PROMIS-fatigue, and EQ5D-5L questionnaires. Biomarkers associated with CR, tissue-based and plasma-based biomarkers will be assessed. Updated enrollment through January 2021 will be presented. Clinical trial information: NCT03793166 .

Phase II clinical study of concurrent durvalumab and radiation therapy (DUART) followed by adjuvant durvalumab in patients with localized urothelial cancer of bladder: Results for primary analyses and survival. BTCRC-GU15-023

398

Background: Bladder cancer (BC) patients (pts) who are cisplatin ineligible/unfit for surgery, or locally advanced and unresectable have limited treatment options. DUART investigates if the combination of radiation therapy (RT) and checkpoint inhibitor, durvalumab (durva) is safe and effective in these pts. We recently reported that the combination was safe, tolerable and disease control rate (DCR) was 92% post durvaRT. Here we present interim efficacy data of our phase II study. Methods: Pts with pure or mixed urothelial bladder cancer (T2-4 N0-2 M0) were enrolled if their tumor was unresectable (35%), were unfit for surgery (50%) and/or cisplatin ineligible (89%). Primary endpoints: a) PFS at 1-yr b) DCR post adjuvant durva; Secondary endpoints: a) CR post durvaRT b) median PFS c) median OS. Pts were treated with durva (1500mg) Q4 wks x2 doses along with definitive RT (64.8Gy, 36 fractions over 7 wks) to the bladder and involved nodes followed by adjuvant durva Q4 wks x 1 yr. Response was evaluated with CT scan and cystoscopy+biopsy. Sample size was based on assumption that this regimen would increase 1 yr PFS by 25% compared to RT alone (50% to 75%); we assumed DCR of 75%. A total of 26 pts were needed to reach a statistical power of at least 80% at one-sided alpha of 5% and to allow for 10% drop out rate. Results: Twenty-six pts (19 males, 7 females) were enrolled, median age 74 yr (51-94). Sixty two percent of pts had >T2 disease, 31% had positive lymph nodes; 62% with unresectable tumor or were unfit for surgery due to comorbidities. At data cut off (9/30/2020) 20/26 pts were evaluable for DCR post adjuvant durva (3 pts with CR post durvaRT, did not get adjuvant therapy; 1 pt withdrew after 3 cycles for adjuvant durva and was on f/u with unconfirmed CR; 2 pts are still on adjuvant durva) and 25/26 for PFS and all 26 pts for OS. Post completion of adjuvant durva, DCR was seen in 70 % (14/20 with 10 CR; 3 PR; 1 SD; 6 PD). One-year probability of PFS was 73% (95% CI 56.4%, 94.4%), median PFS was 18.5 months. One-year OS probability was 83.8% (95% CI 70.4%, 99.7%) with two-year OS probability of 76.8 (95% CI 60.2%, 98%). Median OS has not been reached. We did not observe any correlation between clinical outcome and baseline tumor PD-L1 expression. Conclusions: DurvaRT followed by adjuvant durva demonstrated promising efficacy with 1-year PFS probability of 73%, 1- year OS probability of 83.8% and DCR of 70% in MIBC and locally advanced BC pts with comorbidities. Results will be updated prior to the final presentation. Efficacy was also seen in node (+) pts which led to the design of prospective randomized NCTN study. Induction chemo followed by chemo+durvaRT+ adjuvant durva vs. chemoRT combination is being evaluated in the ongoing EA8185 clinical trial (ECOG-ACRIN/NRG study) for node (+) BC pts. Clinical trial information: NCT02891161.

Efficacy of enfortumab vedotin in advanced urothelial cancer: Retrospective analysis of the Urothelial Cancer Network to Investigate Therapeutic Experiences (UNITE) Study

443

Background: Enfortumab vedotin (EV) is an antibody-drug conjugate targeting Nectin-4, which is FDA approved for patients (pts) with treatment-refractory advanced urothelial cancer (aUC). The activity of EV in pt subsets of interest such as those with distinct histological variants has not been well defined. Methods: A retrospective study of pts with aUC treated with ≥1 dose of EV as standard of care (SOC) or on a clinical trial (if trial results already reported) at 12 US sites was undertaken. Objective response rate (ORR) was investigator-assessed for pts with at least one post-baseline scan or clear evidence of clinical progression. ORR was compared across subsets of interest using proportion test. Results: A total of 184 patients with aUC were included; median age at diagnosis 70, 20% women and 60% with definitive surgery. Most common primary sites included bladder (70%) and upper tract (28%). Majority of pts (72%) had pure urothelial histology (UH) per local review, but 26% had at least a component of variant histology (VH), most commonly squamous (14%), micropapillary (8%) or plasmacytoid (3%). EV was given as monotherapy in 84% and as SOC in 58%; and 81% had ≥ 1 prior treatment in the metastatic (met) setting. ECOG PS was ≥2 in 15%; 37% had baseline neuropathy, 15% diabetes and 9% had GFR≤30. At median follow-up of 37.0 (IQR: 20.5-60.2) months from initial diagnosis, median time from met diagnosis to EV start was 11.7 (IQR: 4.3 – 20.5) months. Median duration of EV was 5.5 (IQR: 1.4 – 6.7) months, and 84% of pts were evaluable for response. ORR for evaluable pts was 53% (8% CR, 45% PR); 25% had SD and 21% PD. Median PFS and OS were not yet reached. At data cutoff in 9/2020, 55% had stopped EV (36% due to PD, 19% intolerance) and 65% were alive. Comparison of ORR in subgroups of interest for 127 evaluable pts treated with EV monotherapy is shown in the table below. Notably, among 31 pts with FGFR3 alterations, 26 were evaluable and ORR was 46%. Conclusions: In a large, retrospective, multi-institutional cohort, responses to EV were observed across a broad range of aUC pts, including pts with variant histology component, FGFR3 alterations and also in populations previously excluded from clinical trials such as pts with GFR<30 and significant baseline comorbidities. No significant differences in ORR were demonstrated for patient subsets of interest. [Table: see text]

Treatment response in the intact primary renal mass (P-Rmass) and its relationship to the overall response to treatment in patients with metastatic renal cell carcinoma (mRCC)

329

Background: With the approval of more effective systemic treatments (syst Rx) such as tyrosine kinase inhibitors (TKI) and immune checkpoint inhibitors (ICI), the impact of cytoreductive nephrectomy (CN) on response to Rx and survival remains unknown. The majority of patients (pts) previously enrolled in clinical trials have had radical nephrectomy (RN) or CN prior to syst Rx. Therefore, the response of the P-Rmass to ICIs and the effect of intact P-Rmass on response to syst Rx is not well described. Methods: A retrospective review of 209 pts with mRCC who were treated with ICI in the first or second-line was conducted. Following the appropriate regulatory process, collaborators from 5 US sites collected clinical, pathological, and outcome data via chart review. The response was investigator-assessed for all pts with at least one post-treatment scan or evidence of clinical progression after treatment initiation. Overall radiographic response (ORR) includes complete response (CR) and radiographic response (Rad-resp) to treatment. Disease control rate (DCR) includes CR, Rad-resp, and stable disease. Results: Median age at diagnosis was 63 yrs and 69% were male. 102 pts (49%) had localized disease at diagnosis and underwent radical or partial nephrectomy, 3 (1%) had ablation/radiation of P-Rmass, 26 (12%) had CN, 9 (4%) had CN after an excellent response to syst Rx, 12 (6%) had a previous nephrectomy but developed a new Rmass (measurable target lesion), and 57 (27%) did not have CN and had an intact P-Rmass. 176 (84%) pts had clear cell histology. 27 (14%) and 23 (12%) had known sarcomatoid and rhabdoid features, respectively. Overall, 77 (37%) pts had a measurable Rmass while receiving syst Rx. 84 (40%), 93 (45%), and 10 (5%) pts received ICI (Ipilimumab/Nivolumab or Nivo), TKI, or Pembrolizumab/Axitinib in the first-line. 143 (68%) and 70 (33%) pts received second- and third-line treatment. 103 (72%) and 28 (19%) pts received ICI and TKI in the second-line, respectively. The best ORR and the Rad-resp in the intact P-Rmass in evaluable pts are summarized in the table below. ORR to ICI in the first or second-line were numerically higher in pts with an intact P-Rmass compared to pts who had nephrectomy, but this difference was not statistically significant (p= .38 and .35 respectively). Conclusions: The intact P-Rmass had a good response (62-70%) to the first-line syst Rx. Although the overall Rad-resp rates to ICI are numerically higher in pts with intact P-Rmass, this difference was not statistically significant. [Table: see text]

Preoperative predictors of biochemical recurrence in a phase II trial of neoadjuvant therapy in very high-risk prostate cancer

74

Background: Understanding the lethal nature of high risk prostate cancer, there is a need for the development of multimodal therapies. Prior studies have confirmed a survival benefit with the addition of docetaxel to androgen deprivation therapy (ADT) in men with metastatic hormone-sensitive prostate cancer (HSPC). We conducted a Phase II trial enrolling men with very high risk localized, locally advanced or oligometastatic prostate cancer (PC) to examine resistance and response to neoadjuvant chemohormonal therapy. This analysis aims to identify the preoperative predictors of biochemical recurrence (BCR). Methods: UW17009 is an IRB-approved open-label, single-arm trial that recruited 26 men with newly diagnosed advanced PC. Patients received ADT and docetaxel for 3 months followed by prostatectomy. The primary endpoint was pathologic complete response rate. A secondary clinical objective was the rate of PSA recurrence 12 months after surgery. The pre-trial PSAs, age, cancer grade, stage, percent tumor involvement of the initial biopsy, metastatic disease on conventional and 18F-DCFPyL PSMA (DCFPyL) PET/CT and MRI imaging, completion of chemohormonal therapy and PSA nadirs following chemohormonal therapy were assessed in relationship to biochemical recurrence. One way ANOVA was used to evaluate differences among continuous values: age, PSA at diagnosis, percent tumor involvement, and PSA nadir after chemo ADT. Fisher’s exact tests were used to evaluate the differences among categorical variables: stage at diagnosis, positive bone scan, and positive PSMA PET. Results: 26 patients were enrolled and underwent neoadjuvant treatment, radical prostatectomy (RP) and lymph node dissection. The median age was 62 (IQR 58-66), mean PSA at diagnosis was 32.8 ng/dl and 88.4% had Gleason 9 cancer. At study initiation, 12/26 patients had metastatic disease detected by DCFPyL-based PSMA PET. Final pathology demonstrated 81%(21/26) had ≥ pT3 and 73%(19/26) patients had negative margins. Positive lymph nodes were found in 10/26(38.5%) patients on final pathology. At week 6 after surgery, 91%(24/26) had undetectable PSA. At a mean follow up of 12.1 months(5.2-21.4), the biochemical recurrence rate is 58%(15/26). Features associated with BCR include stage, % tumor involvement, and positive PSMA PET scan. All patients with positive margins and 9/10 patients with positive nodes at final pathology developed BCR at a mean follow up of 12 months. Conclusions: In this neoadjuvant cohort, stage T2c, elevated PSA, positive pre-operative PSMA PET/CT, and PSA nadir > 1 following chemohormonal therapy predict biochemical recurrence. Clinically, and in the short term, neoadjuvant chemohormonal therapy prior to definitive surgery for very high risk localized and/or oligometastatic PC generates local tumor control with a high rate of negative surgical margins.

Outcomes With First-Line PD-1/PD-L1 Inhibitor Monotherapy for Metastatic Renal Cell Carcinoma (mRCC): A Multi-Institutional Cohort

Introduction: The treatment landscape of metastatic renal cell carcinoma has advanced significantly with the approval of combination regimens containing an immune checkpoint inhibitor (ICI) for patients with treatment-naïve disease. Little information is available regarding the activity of single-agent ICIs for patients with previously untreated mRCC not enrolled in clinical trials. Methods: This retrospective, multicenter cohort included consecutive treatment-naïve mRCC patients from six institutions in the United States who received ≥1 dose of an ICI outside a clinical trial, between June 2017 and October 2019. Descriptive statistics were used to analyze outcomes including objective best response rate (ORR), progression-free survival (PFS), and tolerability. Results: The final analysis included 27 patients, 70% men, median age 64 years (range 42-92), 67% Caucasian, and 33% with ECOG 2 or 3 at baseline. Most patients had intermediate risk (85%, IMDC) with clear cell (56%), papillary (26%), unclassified (11%), chromophobe (4%), and translocation (4%) RCC. All patients had evidence of metastatic disease involving the lungs (59%), lymph node (41%), CNS (19%), liver (11%), adrenal gland (11%), and bone (11%). The median time on ICI was 3.1 (0.1-26.8) months, and the median PFS was 6.3 (95% CI, 0-18.6) months. Among the 21 patients with an evaluable response, the best ORR was 33%, including two complete responses and five partial responses. The ORR was 29% (n = 1 complete response, n = 5 partial response) in clear cell and 5% (n = 1 complete response) in non-clear cell RCC. Adverse events (AEs) of any cause were reported in 37% and included fatigue (11%), dermatitis (11%), diarrhea (7%), and shortness of breath (7%). Significant AEs (30%) included shortness of breath (7%), acute kidney injury (4%), dermatitis (4%), Clostridium difficile infection (4%), cerebrovascular accident (4%), and fatigue (7%). Three patients discontinued therapy due to grade 4 AEs. Conclusions: In this multi-institutional case series, single-agent ICI demonstrated objective responses and was well tolerated in a heterogeneous treatment-naïve mRCC cohort. ICI monotherapy is not the standard of care for patients with mRCC, and further investigation is necessary to explore predictive biomarkers for optimal treatment selection in this setting.

Testicular Cancer, Version 2.2020, NCCN Clinical Practice Guidelines in Oncology

Testicular cancer is relatively uncommon and accounts for <1% of all male tumors. However, it is the most common solid tumor in men between the ages of 20 and 34 years, and the global incidence has been steadily rising over the past several decades. Several risk factors for testicular cancer have been identified, including personal or family history of testicular cancer and cryptorchidism. Testicular germ cell tumors (GCTs) comprise 95% of malignant tumors arising in the testes and are categorized into 2 main histologic subtypes: seminoma and nonseminoma. Although nonseminoma is the more clinically aggressive tumor subtype, 5-year survival rates exceed 70% with current treatment options, even in patients with advanced or metastatic disease. Radical inguinal orchiectomy is the primary treatment for most patients with testicular GCTs. Postorchiectomy management is dictated by stage, histology, and risk classification; treatment options for nonseminoma include surveillance, systemic therapy, and nerve-sparing retroperitoneal lymph node dissection. Although rarely occurring, prognosis for patients with brain metastases remains poor, with >50% of patients dying within 1 year of diagnosis. This selection from the NCCN Guidelines for Testicular Cancer focuses on recommendations for the management of adult patients with nonseminomatous GCTs.

PDIGREE: An adaptive phase III trial of PD-inhibitor nivolumab and ipilimumab (IPI-NIVO) with VEGF TKI cabozantinib (CABO) in metastatic untreated renal cell cancer (Alliance A031704)

TPS5100

Background: First-line treatment of mRCC has rapidly changed to include IPI-NIVO or CABO, with clinical benefit of each based on the Checkmate 214 and CABOSUN (A031203) trials. Combination immunotherapy with VEGF therapies has shown benefit over sunitinib in the JAVELIN 101 and KEYNOTE 426 trials. It is yet unclear which patients (pts) benefit most from combination immunotherapy-VEGF inhibitors, and the optimal sequence of drugs. Methods: In an adaptive, randomized, multicenter phase 3 trial (Alliance A031704, PDIGREE), pts start treatment with induction IPI 1 mg/kg and NIVO 3 mg/kg intravenously (IV) once every 3 weeks. Key inclusion criteria include clear cell mRCC, International Metastatic RCC Database Consortium (IMDC) intermediate or poor risk, Karnofsky performance status > 70, and no prior treatments for mRCC. Based on 3-month radiographic assessment (after completing IPI-NIVO combination), pts with complete responses (CR) undergo maintenance NIVO 480 mg IV every 4 weeks; pts with progression of disease (PD) switch to CABO 60 mg oral daily; pts with non-CR/non-PD are randomized to NIVO 480 mg IV every 4 weeks versus NIVO 480 mg IV every 4 weeks with CABO 40 mg oral daily. Randomization is stratified by IMDC risk criteria and presence of bone metastases. The primary endpoint of the study is overall survival (OS). We hypothesize that 3-year OS will improve to 70% for NIVO-CABO compared to 60% for NIVO alone; to achieve 85% power with a two-sided alpha of 0.05 and exponential distribution, 696 patients will be randomized. Accounting for 30% patients with either CR or PD, and 5% dropout from toxicity, up to 1046 pts will be enrolled. Key secondary endpoints include progression-free survival, 12-month CR rate, overall response rate based on RECIST 1.1 and irRECIST criteria, and toxicity profiles. Quality of life will be assessed based on the FKSI-19, PROMIS-fatigue, and EQ5D-5L questionnaires. Biomarkers associated with CR, tissue-based and plasma-based biomarkers will be assessed. Updated enrollment through May 2020 will be presented. Clinical trial information: NCT03793166 .

Prognostic Value of DNA Damage Response Genomic Alterations in Relapsed/Advanced Urothelial Cancer

BACKGROUND

DNA damage response (DDR) genomic alterations may play an important role in clinical outcomes of patients with urothelial cancer (UC). However, data on the prognostic role of DDR gene alterations in patients with advanced UC remain unclear.

MATERIALS AND METHODS

We retrospectively collected data of three independent patient cohorts with relapsed or advanced UC including 81 and 91 patients from four institutions who underwent FoundationOne genomic sequencing as well as 129 patients selected from The Cancer Genome Atlas bladder cohort. Fisher's exact test was used to determine differences of mutation frequency among the three cohorts. Logistic regression analysis was performed to calculate odds ratio (OR) and 95% confidence interval (CI). Overall survival (OS) was measured from time of initial diagnosis and Cox proportional hazard regression analysis was performed to calculate the hazard ratio (HR) and 95% CI.

RESULTS

DDR genomic alterations were present in 76.5% (62/81), 40.7% (37/91), and 51.2% (66/129) of the three cohorts. ATM alterations consistently correlated with significantly shorter OS, whereas other DDR alterations (excluding ATM) were associated with better prognosis. In 152 patients treated with platinum pooled from the three cohorts, the prognostic value of alterations in ATM as compared with other predefined DDR genes was substantially different (ATM: adjusted HR [HR], 2.03; 95% CI, 1.03-4; p = .04; other DDR: adjusted HR, 0.49; 95% CI, 0.31-0.8; p = .003).

CONCLUSIONS

Genomic alterations in ATM and other DDR genes may have opposite prognostic value in relapsed and/or advanced UC. ATM may have a complex role in UC progression.

IMPLICATIONS FOR PRACTICE

Somatic mutations of DNA damage response (DDR) genes are frequently found in urothelial cancer and appear to play an important role in tumorigenesis, progression, treatment response, and outcomes. In a set of DDR genes, ATM alterations were associated with worse survival, while other alterations were associated with better survival in advanced urothelial cancer. The results of this study suggest a complex role of ATM in tumor progression and call for further studies to determine the underlying mechanisms and biomarker clinical utility.

Polycystic Liver Disease in a Patient With Metastatic Renal Cell Carcinoma: A Case Report

We report a case of rapid evolution of polycystic liver disease in a 76-year-old patient with metastatic renal cell carcinoma who underwent treatment with numerous antineoplastic agents. The aim was to identify a causative etiology for these hepatic cysts of unclear origin. The cystic lesions of the patient were ultimately innumerable and developed rapidly, more than tripling the total liver volume from complete absence over the course of 24 months. The hepatic lesions continued to grow despite an otherwise moderate tumor response. Prior to patient death, the patient remained relatively asymptomatic from the cyst burden and was without signs of grossly metastatic disease. This rapid development of polycystic liver disease most likely represents a previously unseen medication side-effect of cabozantinib or pazopanib. It is important to identify adverse effects of novel antineoplastic agents in this time of oncological medical discovery.

PDIGREE: An adaptive phase III trial of PD-inhibitor nivolumab and ipilimumab (IPI-NIVO) with VEGF TKI cabozantinib (CABO) in metastatic untreated renal cell cancer (Alliance A031704)

TPS760

Background: First-line treatment of mRCC has rapidly changed to include IPI-NIVO or CABO, with clinical benefit of each based on the Checkmate 214 and CABOSUN trials. Combination immunotherapy with VEGF therapies have shown benefit in the JAVELIN 101 and KEYNOTE 426 trials over sunitinib. It is yet unclear which patients (pts) benefit most from combination immunotherapy-VEGF inhibitors, and the optimal sequence of drugs. Methods: In an adaptive, randomized, multicenter, phase 3 trial (Alliance A031704, PDIGREE), pts start treatment with induction IPI 1mg/kg and NIVO 3mg/kg intravenously (IV) once every 3 weeks. Key inclusion criteria include clear cell mRCC, IMDC intermediate or poor risk, Karnofsky performance status >70, and no prior treatments for mRCC. Based on 3-month radiographic assessment (after completing IPI-NIVO combination), pts with complete responses (CR) undergo maintenance NIVO 480mg IV every 4 weeks, pts with progression of disease (PD) switch to CABO 60mg oral daily, and pts with non-CR/non-PD are randomized to NIVO 480mg IV every 4 weeks versus NIVO 480mg IV every 4 weeks with CABO 40mg oral daily. Randomization is stratified by IMDC risk criteria and presence of bone metastases. The primary endpoint of the study is overall survival (OS). We hypothesize that 3-year OS rate will improve to 70% for NIVO-CABO compared to 60% for NIVO alone; to achieve 85% power with a two-sided alpha of 0.05 and exponential distribution, 696 patients will be randomized. Accounting for 30% patients with either CR or PD, and 5% dropout from toxicity, up to 1046 pts will be enrolled. Key secondary endpoints include PFS, 12-month CR rate, ORR based on RECIST 1.1 and irRECIST criteria, and toxicity profiles. Quality of life will be assessed based on the FKSI-19, PROMIS-fatigue, and EQ5D-5L questionnaires. Biomarkers associated with CR and association of IL-6 with treatment benefit will be assessed. Other tissue-based and plasma-based biomarkers are planned. Updated enrollment will be presented. Clinical trial information: NCT03793166.

Phase II trial of neoadjuvant chemohormonal therapy (NAC) in prostate cancer (PC) with response assessment using PSMA PET/MRI

334

Background: Previous studies have shown that addition of docetaxel to androgen deprivation therapy (ADT) significantly improves progression-free survival (PFS) and overall survival (OS) in men with metastatic hormone-sensitive PC. Removal of the primary may also improve outcomes by reducing tumor self-seeding. We are conducting a phase II trial in men with PC to examine the feasibility of NAC, response using PSMA PET/MRI imaging and molecular mechanisms of resistance. Methods: This is an open-label, single-arm trial. Thirty patients with newly diagnosed very high risk localized, locally advanced or oligometastatic PC will receive ADT/docetaxel for three cycles before prostatectomy. The primary endpoint is rate of complete pathologic response. Key secondary objectives include PSA recurrence at month 12 after surgery. Exploratory objectives include tumor response and response heterogeneity in primary and metastatic tumors before and after treatment assessed by PSMA PET/MRI and evaluation of gene expression signatures in cancer cells, prostate stroma, bone marrow microenvironment and circulating tumor cells. Results: To date, 26 of 30 patients have enrolled and completed treatment. Mean age was 61 and mean PSA at time of diagnosis was 32.1 ng/dl. All patients had multi-focal prostate cancer with 23/26 patients with Gleason Grade Group 5. Metastatic disease by conventional imaging was identified in 6/26 patients (5 in lymph nodes [LN] and bone, 1 in LN only). Treatment was overall well tolerated. All patients had multi-focal primary prostate cancer detected on PSMA PET/MRI. All patients had a decline in PSMA PET SUVmax in at least one intraprostatic lesion. Two patients had an increase in SUVmax in at least one intraprostatic lesion that correlated with a resistant tumor focus on histopathology. Conclusions: NAC prior to surgery generates high rates of local tumor control with a heterogeneous response between foci. Primary resistance, identified by increasing PSMA PET SUVmax, is uncommon, however incomplete responses were observed in nearly all patients, suggesting that more cycles of treatment would improve response. PSMA PET/MRI can be used to monitor response and resistance in PC. Clinical trial information: NCT03358563.

Clinical correlation of circulating tumor cell (CTC) PD-L1 and HLA I expression in metastatic renal cell carcinoma (mRCC) using exclusion-based sample preparation technology

721

Background: Despite therapeutic advancement in Vascular endothelial growth factor receptor (VEGF-R) tyrosine kinase inhibitors (TKIs) and immune checkpoint inhibitors (ICIs) for mRCC treatment, there is currently no reliable predictive biomarkers of response or resistance. Single site biopsies provide limited information given the heterogenous nature of mRCC. Liquid biopsies may overcome these limitations; however, prior CTC capture platforms lacked sufficient sensitivity and specificity to achieve clinically useful detection rates. Methods: Given the prevalence of VEGF dependency, and its reliance on hypoxia, we aimed to increase sensitivity and specificity of capturing and identifying mRCC CTCs using carbonic anhydrase IX (CA IX) and CA XII. In addition, traditional markers for cell capture and identification with epithelial cellular adhesion molecule (EpCAM) and cytokeratin (CK) were included. Exclusion-based Sample Preparation technology was used to maximize cell yield. CD45/34/66b positive blood cells were excluded to ensure high specificity in evaluation of PD-L1 and HLA I expression on CTCs. Results: In a preliminary cohort of 21 mRCC pts (treatment: TKI=12, ICI=5, TKI+ICI=2, baseline=2), we identified heterogeneous populations of CTCs with differential expression of CA XII and CK. We detected CK+ CTCs in 20/21 pts (mean= 5/mL; range 0-53), CAXII+ CTCs in 21/21 pts (mean= 1/mL; range 1-9), and CK+/CAXII+ CTCs in 19/21 pts (mean=7/mL; range 0-102). In pts with multiple CTC samples on treatment, there was a high correlation between the number of CK+ CTCs and treatment response (ROC AUC 0.88). PD-L1 expression in CAXII+ CTCs correlated with response to ICI (ROC AUC 0.77) and TKI (ROC AUC 0.73). HLA I expression in CAXII+ CTCs correlated with response to TKI (ROC AUC 0.73) better than ICI (ROC AUC 0.59). Conclusions: Assessment of CTC heterogeneity may provide valuable molecular insights and diversify tools for early detection of therapeutic response and resistance that may guide treatment decision making. This assay is being tested in ongoing Phase II clinical trials.

Concurrent durvalumab and radiation therapy followed by adjuvant durvalumab in patients with locally advanced urothelial cancer of bladder (DUART): Btcrc-GU15-023

513

Background: Bladder cancer (BC) patients (pts) who are cisplatin ineligible/unfit for surgery, unresectable have limited treatment options. In this study, we investigate if the combination of radiation therapy (RT) and checkpoint inhibitor, durvalumab (durva) is safe and effective in these pts. Our results from phase (ph) Ib suggested that the combination was safe. Here we present the response rate post durvaRT and updated treatment related adverse events (TRAEs) amongst our evaluable pts in ph II. Methods: This is a single arm ph Ib-II study for T2-4 N0-2 M0 pts. The ph II primary endpoints a) PFS rate at 1 yr b) disease control rate (DCR); secondary endpoints were a) CR post durvaRT b) PFS c) OS. Pts were treated with durva (1500mg) Q4 wks x2 doses along with definitive RT (64.8Gy, 36 fractions over 7 wks) to the bladder and involved nodes followed by adjuvant durva Q4 wks x 1 yr. Response was evaluated with CT scan and cystoscopy+biopsy post durvaRT. We anticipated that durvaRT followed by durva would increase PFS at 1 yr from 50% to 75% when compared to RT; we assumed DCR of about 75%. A total of 26 pts were needed to reach a statistical power of at least 80% at one-sided alpha of 5% and to allow for 10% drop out rate. Results: Total N = 26 patients (male 19; female 7, median age 74yr). At the time of data cut off, 21/26 pts were evaluable for response post durvaRT. Post completion of durvaRT time point, clinical CR was seen in 15/21 pts (71.4%); PR 1/21 pts (4.7%); SD 4/21 (19%); PD 1/21 (4.7%). DCR was seen in 20/21 pts (95%) post durvaRT. Median follow up from D1 to last follow up was 6.1 mos. Grade ≥ 3 TRAE amongst 26 pts: anemia (1/26), lipase/amylase (1/26), immune nephritis (1/26), dyspnea (gr 4, copd/immune), fatigue (1/26), lymphopenia (6/26). Other TRAEs: Fatigue was the most common TRAE (16/26); UTI (5/26); cystitis (3/26). No fatal TRAEs were observed. Conclusions: DurvaRT demonstrated promising efficacy with clinical CR of 71.4% and DCR of 95% in unresectable, cisplatin ineligible locally advanced BC. It was generally well tolerated. Ph II study has completed accrual and longer-term results will further our understanding of this regimen’s efficacy in locally advanced BC. Clinical trial information: NCT02891161.

Phase II trial of a DNA vaccine encoding prostatic acid phosphatase (pTVG-HP) and nivolumab (Nivo) in patients (pts) with nonmetastatic, PSA-recurrent prostate cancer (PCa)

TPS273

Background: Radical prostatectomy (RP) and radiation therapy (RT) are the gold standard, curative intent treatment for pts with presumed organ-confined PCa. However, about one third of these pts will have progressive or metastatic disease at 10 years (yr). Pts with PSA recurrence without radiographic evidence of metastatic (m) PCa (stage M0) will ultimately develop radiographically apparent mPCa within a median of 8 yr. Pts with rapid PSA doubling time (DT) have a markedly shorter time to mPCa and death. Utilizing an immunotherapeutic approach could utilize the sensitivity and specificity of the immune system to treat microscopic disease and potentially avoid or postpone androgen deprivation therapy (ADT) and its unwanted side effects. Methods: In this single arm, two-stage phase II trial, a total of 21-41 PCa pts with PSA only progression (4 rising PSA with final PSA ≥ 2 ng/mL) after initial RP for presumed organ-confined disease who have no radiographic evidence of mPCa in conventional imaging (CT and bone scan) will be enrolled. Pts with small cell or other variant PCa, or history of ADT other than concurrent with RT are excluded. All pts will be treated with pTVG-HP 100 μg intradermally (id) and Nivo 240 mg IV every (Q) 2 weeks (w) x6, and then pTVG-HP 100 μg id and Nivo 480 mg IV Q4w x9 beginning w12 on study. Pts with PSA on w4 > PSA on day 1 will additionally receive rhGM-CSF 208 μg id, as a vaccine adjuvant, Q2w x4 beginning w4 on study. Pts will be treated until progression or up to a total of 1 yr. Response will be monitored by CT and bone scan Q6 months or as clinically indicated. Primary endpoints are safety and tolerability of this combination and PSA complete response rate (PSA < 0.2 ng/mL). Key secondary endpoints are 2-yr metastasis-free survival, median radiographic progression-free survival, PSA response rate (≤50% of baseline), and changes in PSA DT. Elicited antigen-specific T-cell and/or IgG response and its correlation with PSA response will be explored. Bone mets not detected by conventional imaging and their association with response will be evaluated by Quantitative Total Bone Imaging (QTBI) by NaF PET/CT. Updated enrollment will be presented. Clinical trial information: NCT03600350.

Immunological Correlates of Response to Immune Checkpoint Inhibitors in Metastatic Urothelial Carcinoma

BACKGROUND

The identification of prognostic and/or predictive biomarkers for response to immune checkpoint inhibitors (ICI) could help guide treatment decisions.

OBJECTIVE

We assessed changes in programmed cell death-1 (PD1)/PD1 ligand (PDL1) expression in key immunomodulatory cell subsets (myeloid-derived suppressor cells [MDSC]; cytotoxic T lymphocytes [CTL]) following ICI therapy and investigated whether these changes correlated with outcomes in patients with metastatic urothelial carcinoma (mUC).

PATIENTS AND METHODS

Serial peripheral blood samples were collected from ICI-treated mUC patients. Flow cytometry was used to quantify PD1/PDL1 expression on MDSC (CD33⁺HLADR^-) and CTL (CD8⁺CD4^-) from peripheral blood mononuclear cells. MDSC were grouped into monocytic (M)-MDSC (CD14⁺CD15^-), polymorphonuclear (PMN)-MDSC (CD14^-CD15⁺), and immature (I)-MDSC (CD14^-CD15^-). Mixed-model regression and Wilcoxon signed-rank or rank-sum tests were performed to assess post-ICI changes in immune biomarker expression and identify correlations between PD1/PDL1 expression and objective response to ICI.

RESULTS

Of 41 ICI-treated patients, 26 received anti-PDL1 (23 atezolizumab/3 avelumab) and 15 received anti-PD1 (pembrolizumab) therapy. Based on available data, 27.5% had prior intravesical Bacillus Calmette-Guérin therapy, 42% had prior neoadjuvant chemotherapy, and 70% had prior cystectomy or nephroureterectomy. Successive doses of anti-PDL1 correlated with decreased percentage of PDL1⁺ (%PDL1⁺) M-MDSC, while doses of anti-PD1 correlated with decreased %PD1⁺ M- and I-MDSC. Although pre-treatment %PD1⁺ CTL did not predict response, a greater %PD1⁺ CTL within 9 weeks after ICI initiation correlated with objective response.

CONCLUSIONS

Treatment with ICI correlated with distinct changes in PD1/PDL1-expressing peripheral immune cell subsets, which may predict objective response to ICI. Further studies are required to validate immune molecular expression as a prognostic and/or predictive biomarker for long-term outcomes in mUC.

PDIGREE: An adaptive phase 3 trial of PD-inhibitor nivolumab and ipilimumab (IPI-NIVO) with VEGF TKI cabozantinib (CABO) in metastatic untreated renal cell cancer (Alliance A031704)

TPS4596

Background: First-line treatment of mRCC has rapidly changed to include IPI-NIVO or CABO, with clinical benefit of each based on the Checkmate 214 and CABOSUN trials. Combination immunotherapy with VEGF therapies have shown benefit in the JAVELIN 101 and KEYNOTE 426 trials over sunitinib. It is yet unclear which patients (pts) benefit most from combination immunotherapy-VEGF inhibitors, and the optimal sequence of drugs. Methods: In an adaptive, randomized, multicenter, phase 3 trial (Alliance A031704, PDIGREE), pts will start treatment with induction IPI 1mg/kg and NIVO 3mg/kg intravenously (IV) once every 3 weeks. Key inclusion criteria include clear cell mRCC, IMDC intermediate or poor risk, Karnofsky performance status >70, and no prior treatments for mRCC. Based on 3-month radiographic assessment (after completing IPI-NIVO combination), pts with complete responses (CR) will undergo maintenance NIVO 480mg IV every 4 weeks, pts with progression of disease (PD) will switch to CABO 60mg oral daily, and pts with non-CR/non-PD will be randomized to NIVO 480mg IV every 4 weeks versus NIVO 480mg IV every 4 weeks with CABO 40mg oral daily. Randomization will be stratified by IMDC risk criteria and presence of bone metastases. The primary endpoint of the study is overall survival (OS). We hypothesize that 3-year OS rate will improve to 70% for NIVO-CABO compared to 60% for NIVO alone; to achieve 85% power with a two-sided alpha of 0.05 and exponential distribution, 696 patients will be randomized. Accounting for 30% patients with either CR or PD, and 5% dropout from toxicity, up to 1046 pts will be enrolled. Key secondary endpoints include PFS, 12-month CR rate, ORR based on RECIST 1.1 and irRECIST criteria, and toxicity profiles. Quality of life will be assessed based on the FKSI-19, PROMIS-fatigue, and EQ5D-5L questionnaires. Biomarkers associated with CR and association of IL-6 with treatment benefit will be assessed. Other tissue-based and plasma-based biomarkers are planned. Enrollment will begin this year. Support from UG1CA189823, U24CA196171; https://acknowledgments.alliancefound.org . Clinical trial information: NCT03793166.

Safety and efficacy of nivolumab plus ipilimumab (NIVO+IPI) in patients with advanced renal cell carcinoma (aRCC) with brain metastases: Interim analysis of CheckMate 920

4517

Background: Previous clinical trials of patients (pts) with aRCC, including CheckMate 214, have mostly excluded pts with brain metastases. However, antitumor activity in pts with brain metastases has been observed in pts with melanoma treated with NIVO 1 mg/kg + IPI 3mg/kg and pts with non-small cell lung cancer treated with NIVO 240 mg + IPI 1mg/kg. CheckMate 920 is an ongoing, phase 3b/4 clinical trial of NIVO + IPI treatment in pts with aRCC with a high unmet medical need. Here, we present the safety and efficacy interim results for the cohort of pts with brain metastases. Methods: Pts with previously untreated aRCC of any histology, with asymptomatic brain metastases (not on corticosteroids or receiving radiation), and Karnofsky performance status ≥70% were assigned to treatment with NIVO 3 mg/kg + IPI 1 mg/kg every 3 weeks for 4 doses, followed by NIVO 480 mg every 4 weeks. Pts were treated until disease progression, unacceptable toxicity, or for a maximum of 2 years. The primary endpoint was the incidence of high-grade immune-mediated adverse events (IMAEs). Key secondary endpoints included progression-free survival (PFS) and objective response rate (ORR) by RECIST v1.1 per investigator. Exploratory endpoints included additional safety analyses and overall survival (OS). Results: Overall, 28 patients were enrolled in the brain metastases cohort. With a minimum follow-up of 6.47 months, grade 3-4 IMAEs within 100 days of last dose were reported in 6 cases. The grade 3-4 IMAEs observed in ≥ 1 patient were diarrhea, colitis, diabetic ketoacidosis, immune-mediated hepatitis, hypophysitis, and rash of any type (n = 1 each). No treatment-related grade 5 IMAEs were reported. ORR by RECIST v1.1 per investigator in all treated subjects was 28.6% (95% CI 13.2–48.7). Median PFS in all treated subjects was 9.0 months (95% CI 2.9–not estimable [NE]). Median OS has not been reached (95% CI 13.1–NE). Conclusions: In pts with aRCC and brain metastases who are often excluded from clinical trials, NIVO + IPI treatment showed a safety profile consistent with previous reports of this dosing regimen, with encouraging antitumor activity. Clinical trial information: NCT02982954.

Prognostic value of genomic alterations in DNA damage response (DDR) genes in relapsed/advanced bladder cancer (BCa)

427

Background: DDR defects play an important role in tumorigenesis, progression, treatment response and outcomes of BCa. We previously showed DDR mutations were associated with better prognosis in relapsed/advanced (TxN2-3M0-1) BCa. In this study, we aimed to update and validate our findings in 3 independent datasets. Methods: 81 BCa patients (pts) who had FoundationOne tumor tissue genomic sequencing (315 cancer-related genes) were used as discovery dataset. Validation dataset 1 consisted of additional 91 pts with FoundationOne test. Validation dataset 2 consisted of 129 relapsed/advanced pts from TCGA BCa cohort. Overall survival (OS) was measured from time of initial BCa diagnosis to death or last follow-up. Cox proportional hazard regression analysis was performed to calculate the hazard ratio (HR) and 95% confidence interval (CI). Logistic regression analysis was performed to calculate odds ratio (OR) and 95% CI. A panel of 32 DDR genes (excluding ATM) were used for analyses because ATM mutation was a negative prognostic factor in our prior study. Results: DDR mutations were present in 76.5% (62/81), 40.7% (37/91) and 51.2% (66/129) pts of the 3 datasets. They were associated with longer OS (adjHR = 0.39, 95% CI 0.21–0.73, p = 0.003) in the discovery dataset, which were confirmed in two validation datasets (Validation 1: adjHR = 0.51, 95% CI 0.26–1.03, p = 0.059; Validation 2: adjHR = 0.62, 95% CI 0.39–0.97, p = 0.038). There was a trend for longer OS with increased number of DDR mutations in individual pts. Pts carrying ≥3 DDR mutations had the best prognosis (data not shown). In 144 cisplatin or carboplatin-treated pts pooled from the 3 cohorts, pts with DDR mutations were more likely to have objective response (OR = 1.81, 95% CI 0.85–3.92 for any DDR mutations; OR = 3.65, 95% CI 0.91–14.7 for ≥3 DDR mutations) and longer overall survival (HR = 0.61, 95% CI 0.38–0.98 for any DDR mutations; HR = 0.49, 95% CI 0.19–1.27 for ≥3 DDR mutations). Conclusions: DDR mutations (excluding ATM gene and especially ≥3) correlated with better outcomes in relapsed/advanced BCa. Further exploration of the deleterious nature and functional impact of alterations is critical along with prospective validation in ongoing trials.

ATM mutation is associated with shorter overall survival in relapsed/advanced urothelial cancer

370

Background: Somatic mutations of ATM are frequently found in UC and have been associated with a better response to cisplatin-based neoadjuvant chemotherapy. However, we previously showed ATM mutations were associated with a short survival in UC (PMID: 29682192 ). In this study, we focused on prognostic values of mutations in ATM in tumors of patients with relapsed or advanced (TxN2-3M0-1) UC through three independent datasets. Methods: 81 UC pts who underwent FoundationOne genomic sequencing (315 cancer-related genes) were used as a discovery dataset. Results were then validated in additional 91 pts with UC who received FoundationOne test (collected separately) and 129 relapsed/advanced UC patients selected from 412 TCGA bladder cohort. Fisher Exact test was used to determine difference of ATM mutation rates. Logistic regression analysis was performed to calculate odds ratio (OR) and 95% confidence interval (CI). Overall survival (OS) was measured from time of initial diagnosis and Cox proportional hazard regression analysis was performed to calculate the hazard ratio (HR) and 95% CI. Results: The median ages of the 3 cohorts were 65 (44–84), 65 (21–91) and 67 (45–-90). The majority of pts were Caucasians (86.4%, 75.8% and 81.4%) and ever smokers (77.8%, 67% and 76.7%). ATM mutations were present in 14.8% (12/81), 11% (10/91) and 6.2% (8/129) of the three cohorts (Fisher Exact, p = 0.118). In all three groups of pts, ATM mutations consistently correlated with a significantly shorter OS (Discovery: HR = 2.25, 95% CI, 1.03–4.89, p = 0.041; Validation 1: HR = 3.15, 95% CI, 1.17–8.44, p = 0.023; and Validation 2: HR = 2.17, 95% CI, 0.99–4.75, p = 0.051). In 144 pts treated with cisplatin or carboplatin pooled from the three cohorts, ATM mutations correlated with a non-significantly higher objective response rate (OR = 1.54, 95% CI 0.44–5.35, p = 0.5), but were still associated with a poorer survival (HR = 1.95, 95% CI 1.00–3.83, p = 0.05). Conclusions: These results suggest that ATM mutations may be considered as a negative prognostic biomarker in relapsed/advanced UC pts. Further studies are required to determine the underlying mechanisms.

Treatment selection for men with metastatic prostate cancer who progress on upfront chemo-hormonal therapy

BACKGROUND

Androgen deprivation therapy plus docetaxel (D-ADT) increases overall survival (OS) in men with high-volume, metastatic hormone-sensitive prostate cancer (mHSPC). Although the vast majority of men initially respond to D-ADT, most will progress and develop castration-resistant prostate cancer (CRPC). Little is known about the optimal treatment sequence for men with progressive disease on D-ADT.

PATIENT AND METHODS

Retrospective analysis of consecutive mHSPC patients treated with ≥3 cycles of D-ADT at Cleveland Clinic and University of Wisconsin-Madison was undertaken. The primary end-points included radiographic progression free survival (rPFS) and OS with first-line treatment for metastatic CRPC (mCRPC).

RESULTS

Final analysis included 136 patients, median age 65 (range 35-86), 77% GS ≥ 8, and 79% with high-volume disease who received ≥3 cycles of docetaxel. Undetectable PSA values at 12 and 24 months were observed in 32% and 25% of patients, respectively. Median time to CRPC (biochemical, clinical, or radiographic) was 19.6 months (16.6-22.6). Sixty patients (44%) received ≥1 treatment for CRPC: 48 patients (80%) received a second-generation hormonal therapy (sHT). Among these, 22 received abiraterone acetate, 20 enzalutamide, and six a novel CYP-17 inhibitor on trial (ASN-001). Five patients (8%) received sipuleucel-T; four (7%) radium-223, five (8%) chemotherapy (two carboplatin-based, two single agent cabazitaxel, one single agent docetaxel) and three other. Patients receiving sHT as the first treatment for mCRPC had a median rPFS of 9.0 months (95%CI, 6.9-11.2) compared with 3.0 months (95%CI, 1.5-4.5) for patients who received a non-sHT (P = 0.024). The choice of first therapy for mCRPC was independent of GS (P = 0.909), visceral disease (P = 0.690) and time to CRPC (P = 0.844). Longer OS correlated with time to CRPC (P = 0.010) and first treatment for CRPC with sHT (P = 0.005).

CONCLUSIONS

For patients with progressive disease on D-ADT, subsequent treatment with a sHT is associated with a longer rPFS and OS.

Evaluation of Response to Enzalutamide Consecutively After Abiraterone Acetate/Prednisone Failure in Patients With Metastatic Castration-resistant Prostate Cancer

INTRODUCTION

Treatment of metastatic castration-resistant prostate cancer (mCRPC) has evolved significantly during the past decade, and the preferred combination and/or sequence of these treatments remains controversial. In this retrospective study, we explored clinical and pathologic factors that could predict response to consecutive treatment with enzalutamide (ENZA) after disease progression (PD) on abiraterone acetate and prednisone (AA/P).

PATIENTS AND METHODS

Data were collected from 40 consecutive patients with mCRPC who were treated with ENZA without other interim therapy after progression on AA/P.

RESULTS

The median time from prostate cancer initial diagnosis to AA/P treatment was 6.2 (range, 0.9-16.3) years. The median prostate-specific antigen (PSA) progression-free survival (PSA-PFS) from treatment initiation was 8.5 months (95% confidence interval [CI], 7.1-10.1 months) and 2.3 months (95% CI, 1.8-3.4 months) on AA/P and ENZA, respectively. The median time to PD from treatment initiation was 9.7 months (95% CI, 7.1-12.4 months) and 3 months (95% CI, 2.3-4.1 months) on AA/P and ENZA, respectively. The correlations were weak between the best percent change in PSA on ENZA and time from diagnosis to AA/P initiation, best absolute or percentage change in PSA on AA/P, time to PSA progression or PD on AA/P. Patients with longer than the median duration of treatment with AA/P (11.73 months) had longer PSA-PFS on ENZA (median 2.8 vs. 1.9 months; P = .035).

CONCLUSIONS

In this retrospective analysis, we did not find any clinical or pathologic factors associated with response to ENZA administered consecutively after AA/P. Patients with longer than median AA/P treatment duration had longer PSA-PFS on ENZA. Further evaluations and validation are greatly needed.

HSD3B1(1245A>C) variant regulates dueling abiraterone metabolite effects in prostate cancer

BACKGROUND

A common germline variant in HSD3B1(1245A>C) encodes for a hyperactive 3β-hydroxysteroid dehydrogenase 1 (3βHSD1) missense that increases metabolic flux from extragonadal precursor steroids to DHT synthesis in prostate cancer. Enabling of extragonadal DHT synthesis by HSD3B1(1245C) predicts for more rapid clinical resistance to castration and sensitivity to extragonadal androgen synthesis inhibition. HSD3B1(1245C) thus appears to define a subgroup of patients who benefit from blocking extragonadal androgens. However, abiraterone, which is administered to block extragonadal androgens, is a steroidal drug that is metabolized by 3βHSD1 to multiple steroidal metabolites, including 3-keto-5α-abiraterone, which stimulates the androgen receptor. Our objective was to determine if HSD3B1(1245C) inheritance is associated with increased 3-keto-5α-abiraterone synthesis in patients.

METHODS

First, we characterized the pharmacokinetics of 7 steroidal abiraterone metabolites in 15 healthy volunteers. Second, we determined the association between serum 3-keto-5α-abiraterone levels and HSD3B1 genotype in 30 patients treated with abiraterone acetate (AA) after correcting for the determined pharmacokinetics.

RESULTS

Patients who inherit 0, 1, and 2 copies of HSD3B1(1245C) have a stepwise increase in normalized 3-keto-5α-abiraterone (0.04 ng/ml, 2.60 ng/ml, and 2.70 ng/ml, respectively; P = 0.002).

CONCLUSION

Increased generation of 3-keto-5α-abiraterone in patients with HSD3B1(1245C) might partially negate abiraterone benefits in these patients who are otherwise more likely to benefit from CYP17A1 inhibition.

FUNDING

Prostate Cancer Foundation Challenge Award, National Cancer Institute.

Abstract 4585: Development of multi-marker capture and analysis of circulating tumor cells in renal cell carcinoma

Purpose: Circulating biomarkers are an emerging tool to monitor treatment response and the emergence of resistant phenotypes. However, studies of circulating biomarkers, including circulating tumor cells (CTCs), in patients with clear cell renal cell carcinoma (ccRCC) have been limited due to difficulty in biomarker identification. Platforms relying on EpCAM and cytokeratin to identify CTCs have been limited due to significant phenotypic and intrapatient heterogeneity in renal cancer. Carbonic anhydrase IX (CAIX) and XII (CAXII) are more broadly expressed in ccRCC and recently been shown to capture CTCs from patients with ccRCC. However, downregulation of these targets can also occur; EpCAM is also expressed on a subset of cells that could go undetected if only CAIX was used to capture these cells. The aim of this study is to optimize multi-marker capture and analysis of ccRCC CTCs using EpCAM, CAIX and CAXII for further molecular analysis.

Methods: We utilized the VERSA platform, an integrated CTC capture and analysis technology, to optimize capture of multiple ccRCC cell lines using antibodies to CAIX and/or EpCAM. To maximize the capture efficiency of ccRCC CTCs, we altered the magnetic particle type, antibody concentration, and tested both direct and indirect capture methods. Once an optimal method of capture was determined, we captured CTCs in an initial cohort of ten patients with ccRCC. CTCs were identified as cells that were captured by either CAIX or EpCAM, had an intact nucleus, were negative for CD45/CD34/CD66b, and positive for cytokeratin.

Results: Capture of cell lines show that a combined CAIX + EpCAM capture was more efficient than single antibody capture using either EpCAM or CAIX alone. The type of magnetic particle used in the assay also affected capture efficiency. Sera-Mag beads (GE Healthcare) captured significantly more cells than FlowComp Dynabeads (Life Technologies) (94% vs 76%). Further increases in efficiency were made by incubating with antibody prior to bead conjugation (indirect binding, 94%) when compared to incubating the cells with antibody-conjugated beads (direct binding, 98%). This may result from increased accessibility of free antibody to partially obstructed antigens that is unique to renal cell carcinoma. This optimized assay has now been applied to ccRCC patients and has identified CTCs in up to 90% of patients with metastatic disease.

Conclusions: We have increased the capture efficiency and identification of ccRCC cells by capturing with a combination of CAIX and EpCAM antibodies and optimizing bead and binding conditions. In doing so, we are able to identify and interrogate populations of CTCs that would be lost in capture methods that rely on EpCAM alone. These assays are now being utilized in multiple biomarker and therapeutic trials for patients with clear cell renal cell carcinoma.

Citation Format: Rory M. Bade, Benjamin K. Gibbs, Jamie M. Sperger, Christos Kyriakopolous, Hamid Emamekhoo, Rana R. McKay, Toni K. Choueiri, Joshua M. Lang. Development of multi-marker capture and analysis of circulating tumor cells in renal cell carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4585.

ATM/RB1 mutations predict shorter overall survival in urothelial cancer

BACKGROUND

Mutations of DNA repair genes, e.g. ATM/RB1, are frequently found in urothelial cancer (UC) and have been associated with better response to cisplatin-based chemotherapy. Further external validation of the prognostic value of ATM/RB1 mutations in UC can inform clinical decision making and trial designs.

RESULTS

In the discovery dataset, ATM/RB1 mutations were present in 24% of patients and were associated with shorter OS (adjusted HR 2.67, 95% CI, 1.45-4.92, p = 0.002). There was a higher mutation load in patients carrying ATM/RB1 mutations (median mutation load: 6.7 versus 5.5 per Mb, p = 0.072). In the validation dataset, ATM/RB1 mutations were present in 22.2% of patients and were non-significantly associated with shorter OS (adjusted HR 1.87, 95% CI, 0.97-3.59, p = 0.06) and higher mutation load (median mutation load: 8.1 versus 7.2 per Mb, p = 0.126).

MATERIALS AND METHODS

Exome sequencing data of 130 bladder UC patients from The Cancer Genome Atlas (TCGA) dataset were analyzed as a discovery cohort to determine the prognostic value of ATM/RB1 mutations. Results were validated in an independent cohort of 81 advanced UC patients. Cox proportional hazard regression analysis was performed to calculate the hazard ratio (HR) and 95% confidence interval (CI) to compare overall survival (OS).

CONCLUSIONS

ATM/RB1 mutations may be a biomarker of poor prognosis in unselected UC patients and may correlate with higher mutational load. Further studies are required to determine factors that can further stratify prognosis and evaluate predictive role of ATM/RB1 mutation status to immunotherapy and platinum-based chemotherapy.

The association between HSD3B1 genotype and steroid metabolism in normal and prostate cancer (PCa) tissue

TPS155

Background: The common germline variant HSD3B1(1245C) encodes for a gain-of-function in 3βHSD1 which is associated with a shorter duration of response to androgen deprivation therapy (ADT) and more rapid disease progression to castration resistant PCa (CRPC) as shown previously in 5 independent cohorts. Therefore, evaluating the effect of such genotype variation on the level of steroid metabolites and the intratumoral dihydrotestosterone (DHT) concentration in benign and tumor tissue of men on ADT is of significant importance. We hypothesize that patients with homozygous HSD3B1 (1245C) genotype (HZ) will have a sustained androgen synthesis from extragonadal precursor steroids and higher concentrations of DHT compared to patients with wild-type HSD3B1 (1245A) (WT) inheritance in the context of testosterone suppression. In addition, it is expected that heterozygous HSD3B1 (1245C) patients (HTZ) will have intermediate levels of DHT. We also hypothesize that treatment with androgen receptor (AR) antagonist (apalutamide) will reverse the effects of elevated DHT on AR signaling in benign and malignant prostate tissue. Methods: In this Phase II trial (NCT02770391), men with newly diagnosed intermediate or high-risk PCa (GS ≥ 4+3, ≥cT2b, or PSA ≥ 10) who are scheduled to undergo radical prostatectomy (RP) will be enrolled into 3 groups based on their HSD3B1 genotype. All pts will receive one dose of 7.5 mg leuprolide injection and apalutamide 240 mg/day orally for 28 ± 3 days prior to RP. DHT and 7 other androgens (including testosterone, Dehydroepiandrosterone, Androstenedione) will be evaluated in the normal and malignant prostate tissue as well as serum samples obtained at the time of RP. AR regulated genes expression (including PSA, FKBP5, TMPRSS2) will be compared across 3 genotypes. A sample size of 57 pts (WT = 30, HTZ = 15, HZ = 12) will allow a statistical power of > 80% (with two-sided α = 0.05) to detect a 4-fold trend in DHT concentrations in the resected prostate tissue (primary endpoint) as well as similar trend in other androgens (secondary endpoint). As of Oct 2017, 16 of planned 57 pts have been enrolled. Clinical trial information: NCT02770391.

Treatment patterns for metastatic hormone-sensitive prostate cancer (mHSPC) progressing after up-front docetaxel in combination with androgen deprivation therapy (D-ADT)

305

Background: D-ADT increases overall survival (OS) in men with mHSPC. All patients (pts) however progress and develop castration-resistant prostate cancer (CRPC). Little is known about response to subsequent therapy and outcomes in this setting. Methods: Retrospective analysis of consecutive mHSPC pts treated with ≥3 cycles of D-ADT at Cleveland Clinic and University of Wisconsin-Madison. We aimed to describe baseline, progression characteristics, treatment choices, sequence and outcome of subsequent therapy. Results: A total of 146 mHSPC pts were treated with D-ADT (6% 1-2 cycles; 94% ≥3 cycles). Final analysis included 136 pts, median age 65 (range 35-86), 65% GS≥8, 79% high-volume disease. Median number of D cycles was 6 (1-6). PSA declined to “0” at 12 and 24 months in 32% and 25% of pts, respectively. Median time to CRPC (biochemical, clinical or radiographic) was 19.6 months (95% CI, 16.6-22.6). 57 pts (42%) received ≥1 subsequent treatment after CRPC [46 hormonal therapy (HT) (21 abiraterone acetate, 19 enzalutamide, 6 ASN-001); 4 Sipuleucel-T; 4 radium-223, 5 chemotherapy (2 carboplatin-based, 2 cabazitaxel, 1 D); 3 temsirolimus/bevacizumab]. Treatment response was independent from time to CRPC (≥12 months, p = 0.264). Pts receiving HT as the first subsequent treatment had a median rPFS of 13.3 months (95% CI, 10.1-16.5) compared with 3.1 months (95% CI, 0-15.8) for non-HT (p = 0.332). Treatment choice was independent of GS (p = 0.513), visceral disease (p = 0.374) and time to CRPC (p = 0.500). Most CRPC pts treated with ≥2 lines of therapy received one HT (n = 21) followed by a different HT (43%), chemo (38%), radium-223 (14%) or olaparib (10%). 57% of pts were alive at 2 years. Longer OS correlated with time to CRPC (p = 0.010) and first subsequent treatment with HT (p = 0.009) but not with visceral disease (p = 0.258), GS (p = 0.599) or sequence of therapies received (HT/HT vs HT/non-HT, p = 0.836). Conclusions: Prior D-ADT did not preclude subsequent treatment response in CRPC pts, independent of time to CRPC. The choice of first-line treatment for CRPC may impact survival in favor of those who start HT.

Response to platinum-based therapy (PBT) and immune checkpoint inhibitors (ICI) in metastatic urothelial carcinoma (mUC) patients (pts) with genomic alterations (GA) in homologous recombination repair (HRR) genes

447

Background: Deleterious GA in genes of the HRR pathway and tumor mutational load (TML; mutations/Mb) were shown to predict response to PBT and ICI; further validation can be informative. We assessed the predictive role of such GA in mUC. Methods: Tissue from mUC pts treated with PBT or ICI in the 1st line setting underwent genomic profiling (GP) via FoundationOne. Pts were analyzed in 2 groups based on the presence of potentially function-impairing GA (using classification criteria) in any of 15 pre-selected HRR genes. Exploratory assessment of overall response rate (ORR; RECIST v1.1), progression-free and overall survival (PFS, OS) based on presence of relevant GA was performed using Cox proportional hazards model, Kaplan Meier estimates, and Fisher’s exact test. Results: GA were noted in 22% of 88 identified mUC pts with available GP from 2012 to 2017. The most common deleterious GA were BRCA1/2 (n=6), ATM (n=6), CDK12 (n=2), BRIP1 (n=2), BARD1 (n=1), RAD51 (n=1), and CHEK2 (n=1). Of 88 pts, 62 were treated in the 1st line setting (median age 69; 27% women; 42% never smokers). Of these 62 pts, 42 received PBT and 20 ICI. Deleterious GAs were noted in ≥1 HR gene in 24% and 10% of pts in each group, respectively. The ORR was 40% and 43% in PBT pts with and without GA in any HRR gene, respectively. Analysis showed a median OS (10.6 vs 14.3 months, p=0.11), median PFS (6.1 vs 7.9 months, p=0.05), and no difference in the rate of responders vs non-responders (p=0.53) to PBT in pts with vs without GA in HRR genes. Analysis of ICI treated pts was not feasible (only 2 had GA in HRR genes). Median TML was 8 and 10 in pts with available data treated with PBT and ICI, respectively. There was no correlation between TML and response to either 1st line therapy (analysis underpowered). Of pts with GA in HR genes, the one with the longest OS had 2 GA (CDK12; FANCA). Conclusions: Deleterious GAs in genes of HRR pathway are frequent in mUC supporting TCGA and other datasets but did not confer sensitivity to 1st line PBT in our relatively small cohort. Further biomarker validation combined with LOH assessment can inform decision making and clinical trial designs.

Immunological correlates of response to immune checkpoint inhibitors (ICI) in metastatic urothelial carcinoma (mUC) patients (pts)

454

Background: Identification of biomarkers predictive of response to ICI could help guide treatment (tx) decisions. We assessed the correlation between PD1/PDL1 expression in key immunomodulatory subsets (myeloid-derived suppressor cells [MDSC]; CD8+ T cells) and tx response in mUC pts treated with ICI. Methods: Serial peripheral blood samples were collected from mUC pts treated with ICI. Flow cytometry was used to quantify PD1/PDL1 expression in MDSC (CD33+HLADR−) and CD8+ T cells (CD8+CD4−) from live peripheral blood mononuclear cells. MDSC were subdivided into monocytic (M)-MDSC (CD14+CD15−), polymorphonuclear (PMN)-MDSC (CD14− CD15+), and immature (I)-MDSC (CD14− CD15−). Mixed-model regression and Wilcoxon rank-sum tests were performed to assess post-ICI changes in immune marker expression and identify correlations between PD1/PDL1 expression and best overall response (BOR) to ICI. Results: Of 36 ICI-treated pts with ≥2 blood samples, 24 received anti-PDL1 (22 atezolizumab/2 avelumab; [A]) and 12 received anti-PD1 (pembrolizumab [P]). 78% were men, median age 69 (46–81), 28% never smokers, 19% had prior intravesical BCG, 39% prior neoadjuvant chemotherapy, and 64% prior cystectomy. BOR to ICI included 3 PR/14 SD/7 PD (A) and 1 CR/2 PR/6 SD/3 PD (P). Successive doses of A correlated with decreased %PDL1+ M-MDSC (mean change −5.26/dose; p = 0.009), while those of P correlated with decreased %PD1+ M- and I- MDSC (mean change −1.55 and −1.14/dose; p = 0.04 and 0.02, respectively). Though pre-tx %PD1+ CD8+ T cells did not predict BOR, greater PD1 expression by CD8+ T cells within 12 weeks after ICI initiation correlated with BOR (Table). Conclusions: ICI tx correlated with distinct changes in PD1/PDL1 expression by specific peripheral immune cell subsets. Responders to ICI had higher % of PD1+ CD8+ T cells after ICI than non-responders, though pre-tx % were comparable between groups. Further validation of these and other potential blood/tissue biomarkers is ongoing. [Table: see text]

HSD3B1 genotype and abiraterone (Abi) metabolites in patients (pts) with prostate cancer (PCa)

325

Background: Abi, a potent inhibitor of 17α-hydroxylase/17,20-lyase (CYP17A1), is an oral treatment option for metastatic PCa in castration-resistant and -sensitive settings. Abi is converted to ∆4, 3-keto-abi (D4A) by 3β-hydroxysteroid dehydrogenase (3βHSD). D4A is further metabolized to multiple downstream steroidal metabolites including 3-keto-5α-Abi (5αA), which is an androgen receptor (AR) agonist and might affect response and/or resistance to Abi. The common HSD3B1(1245C) germline variant encodes for a 3βHSD missense that increases enzyme activity that allows tumors to utilize extragonadal androgens and is a predictive biomarker of resistance to ADT and sensitivity to CYP17A1 inhibition. However, the more active 3βHSD protein might increase 5αA synthesis, possibly limiting the clinical benefit of Abi. Methods: Blood was collected from CRPC pts on Abi and drug metabolites (MA) were extracted from serum, and analyzed by mass spectrometry. To correct for pharmacokinetics (PK) of time from last dose to blood draw in this cohort, data were normalized to the 8-hour time point of a separate PK study of Abi MAs and grouped by HSD3B1 genotype. HSD3B1 genotype was determined using germline DNA. Results: Abi MAs were evaluated in the sera of 30 CRPC pts on Abi. Abi, D4A, 5αA, were detectable in the sera of all pts. There were 8, 19, and 3 pts with homozygous wild-type, heterozygous, and homozygous variant HSD3B1 genotypes. HSD3B1 variant allele inheritance was associated with a statistically significant increase in 5αA concentrations, with highest concentration of 5αA MAs observed in homozygous variant HSD3B1 pts (Table). Conclusions: Germline HSD3B1 variant genotype is associated with higher 5αA metabolites with possible implications for AR stimulation and adverse clinical outcomes on Abi. [Table: see text]

Serial changes in PD1/PDL1 expression in metastatic urothelial carcinoma (mUC) patients (pts) treated with immune checkpoint blockade (CPB)

109

Background: Since CPB may alter immune marker expression in key immunomodulatory populations such as myeloid-derived suppressor cells (MDSC) and CD8+ cytotoxic T lymphocytes (CTL), we evaluated PD1/PDL1 expression in longitudinal samples from mUC pts treated with CPB. Methods: Serial peripheral blood samples were collected from mUC pts who received CPB. PD1/PDL1 and VISTA expression was measured in MDSC (CD33+HLADR−) and CTL (CD8+CD4−) from live peripheral blood mononuclear cells using flow cytometry. MDSC subsets were further defined as (G)ranulocytic (CD15+CD14−), (M)onocytic (CD15−CD14+), and (I)mmature (CD15−CD14−). PD1/PDL1 and VISTA expression was presented as % of each MDSC subset or CTL. Wilcoxon signed-rank tests and mixed-model regression analyses were performed to assess changes in immune marker expression after CPB. Results: Of 30 CPB-treated pts with ≥ 2 blood samples for analysis, 21 received anti-PDL1 (20 atezolizumab/1 avelumab; [A]) and 9 received anti-PD1 (pembrolizumab [P]). Median age at diagnosis was 69.5 (46–81), 77% men, 33% never smokers, 63% pure UC, 70% bladder primary, 20% prior intravesical BCG, 37% prior neoadjuvant chemotherapy, 63% prior cystectomy. Best overall responses to CPB were 3 PR/13 SD/5 PD (A) and 1 CR/1 PR/4 SD/3 PD (P). Successive doses of A correlated with decreased %PDL1+ M-MDSC, while those of P correlated with decreased %PD1+ M- and I- MDSC (Table). No significant changes in VISTA expression were detected. In 11 A-treated pts with samples before/after the 1st dose, %PDL1+ M- and I- MDSC decreased (median change −25.5 and −5.7; p = 0.02 and 0.03) and %PD1+ CTL increased (median change +2.4; p = 0.02) between 1st and 2nd samples. Conclusions: In this mUC pt cohort, distinct post-tx changes in %PD1/PDL1 in MDSC subsets and CTL occurred based on CPB (anti-PD1 vs anti-PDL1). Further analysis of correlations between CPB, immune marker expression, clinicopathologic factors, and outcomes is ongoing in a larger cohort. Mean absolute change in marker expression per dose in pts treated with CPB. [Table: see text]

ATM/RB1 mutations to predict shorter overall survival (OS) in bladder cancer

4547

Background: DNA repair defect plays an important role in tumorigenesis, progression and treatment outcomes of urothelial cancer. Somatic mutations of ATM/RB1 genes are frequently found in urothelial cancer and have been associated with a better response to cisplatin-based neoadjuvant chemotherapy. However, their prognostic value overall in urothelial cancer have not been determined. Methods: Exome sequencing data of 130 urothelial bladder cancer patients (pts) from The Cancer Genome Atlas (TCGA) dataset were analyzed as a discovery cohort to determine the prognostic value of ATM and RB1 mutations. Results from discovery dataset were further validated by an independent cohort of 79 advanced urothelial cancer pts who received comprehensive genomic sequencing for urothelial cancer with FoundationOne. OS was measured from time of initial diagnosis and Cox proportional hazard regression analysis was performed to calculate the hazard ratio (HR) and 95% confidence interval (CI). Results: In the discovery dataset, somatic mutations of ATM/RB1 genes were present in 24% of pts and were associated with significantly shorter OS [all stages: adjusted HR = 2.67, 95% CI, 1.45–4.92, P = 0.002; stage II-III only: adjHR = 2.76, 95% CI, 1.23–6.20, P = 0.014]. There was high mutation load in pts carrying ATM/RB1 mutations (median mutation count: 196 versus 160, P = 0.09). In the validation (stage IV) dataset, ATM/RB1 mutations were present in 31.7% of pts and tended to associate with shorter OS (adjHR = 1.97, 95% CI, 0.89–4.40, P = 0.094) and higher mutation load (median mutation load: 8.1 versus 7.2 per Mb, P = 0.136), although statistical significance was not reached. Conclusions: These results suggest that ATM/RB1 mutations may be considered as a poor prognostic biomarker in unselected urothelial cancer pts and may correlate with higher mutational load. Further studies are required to determine patient characteristics that can further stratify prognosis based on ATM/RB1 mutation status, and evaluate the potential predictive role of ATM/RB1 mutation status in response to immunotherapy.

Prognostic value of DLL3 expression and clinicopathologic features in small cell bladder cancer (SCBC)

382

Background: SCBC is rare with limited data on treatment and outcomes. DLL3, a Notch pathway protein, is expressed in small cell lung cancer (SCLC) and neuroendocrine tumors. Phase I/II trials of the anti-DLL3 antibody-drug conjugate, rovalpituzumab tesirine, are ongoing in SCLC and other solid tumors. DLL3 expression in SCBC and its prognostic implications are unknown. Methods: A retrospective review of clinicopathologic features of 63 patients (pts) with biopsy-confirmed SCBC at Cleveland Clinic (1993-2016) was conducted. Percentage (%) of small cell component (SC%) was defined by independent pathology review in all pts. The % of tumor cells expressing DLL3 (DLL3%) was assessed in 53 pts. Multivariable analyses (MVA) were used to identify predictors of overall survival (OS), progression-free survival (PFS) and time to progression (TTP) (p ≤ .05). Results: Median age was 71 (39-90), 83% were men, 77% current/former smokers, 41 (65%) had cystectomy and 22 (35%) only TURBT. Estimated median OS, PFS and TTP were 22.8, 13.7 and 21.1 months from diagnosis. Median SC% was 100% (5-100%) and 79% of tumors were ≥ 50% SC. DLL3 expression of any level was noted in 68% (36/53) of tumors; 58% of tumors had DLL3 expression in > 10% of cells. SC% correlated with DLL3% (r = 0.33, p = .01). In MVA, increased DLL3% was associated with shorter OS and PFS, while increased SC% was associated with shorter PFS and TTP. Higher pT at cystectomy was associated with shorter OS (Table). Conclusions: Higher DLL3 expression and SC% are associated with worse outcomes in SCBC. Most SCBC tumors express DLL3, a therapeutic target tested in clinical trials. Genomic, epigenetic, transcriptomic and PDL1 evaluation in SCBC are also being pursued to define molecular context. DLL3 expression and other prognostic factors. [Table: see text]

Evaluation of patient (Pt), treatment, and prognostic factors in urinary tract adenocarcinoma

408

Background: Adenocarcinoma is a rare histological subtype of urinary tract cancer with limited data regarding risk factors, effectiveness of treatment, and prognostic factors. Methods: To identify prognostic features, we evaluated demographics, treatment, and progression-free and overall survival (PFS, OS) in a retrospective review of 49 pts with adenocarcinoma of the bladder (n=35), ureter (n=1), or urethra (n=13) evaluated at Cleveland Clinic from January 2000 to April 2016. Uni- and multi- variable analyses (UVA, MVA) were used to identify prognostic factors. OS was measured from diagnosis to death and PFS from diagnosis to first of recurrence/progression or death. Results: 25 (51%) pts were women, median age at diagnosis was 62 (33-82), 30 pts (61%) presented with hematuria, and 13/36 (36%) had hydronephrosis. Treatment included cystectomy in 43 pts (88%), neoadjuvant chemotherapy in 3 pts (MVAC, gemcitabine/cisplatin, paclitaxel/cisplatin), adjuvant chemotherapy in 2 pts (gemcitabine), and systemic therapy for advanced or recurrent disease in 6 pts. Overall, 23 pts (47%) recurred/progressed and 31 (63%) died [12 without recurrence/progression]. Estimated median OS and PFS from diagnosis were 38.1 and 24.5 months, respectively. Pts with hydronephrosis at time of diagnosis had shorter PFS (p=0.06) and OS (p=0.007). Among the cystectomy pts, MVA identified pN stage and presence of signet-ring cells or papillary component as the only independent predictors of OS, while pN stage was the only independent predictor of PFS. Combining these factors, 3 prognostic groups for OS were identified (Table). Conclusions: pN stage and morphology are independent predictors of OS in pts with urinary tract adenocarcinoma after radical surgery and can stratify pts into distinct prognostic groups. If validated in larger cohorts, these factors could be used for prognostication, clinical decision making, and trial stratification. [Table: see text]

ATM/RB1 mutations to predict shorter overall survival (OS) in bladder cancer

393

Background: DNA repair defect plays an important role in tumorigenesis, progression and treatment outcomes of urothelial cancer. Somatic mutations of ATM/RB1 genes are frequently found in urothelial cancer and have been associated with a better response to cisplatin-based neoadjuvant chemotherapy. However, their prognostic value overall in urothelial cancer have not been determined. Methods: Exome sequencing data of 130 urothelial bladder cancer patients (pts) from The Cancer Genome Atlas (TCGA) dataset were analyzed as a discovery cohort to determine the prognostic value of ATM and RB1 mutations. Results from discovery dataset were further validated by an independent cohort of 79 advanced urothelial cancer pts who received comprehensive genomic sequencing for urothelial cancer with FoundationOne. OS was measured from time of initial diagnosis and Cox proportional hazard regression analysis was performed to calculate the hazard ratio (HR) and 95% confidence interval (CI). Results: In the discovery dataset, somatic mutations of ATM/RB1 genes were present in 24% of pts and were associated with significantly shorter OS [all stages: adjusted HR = 2.67, 95% CI, 1.45–4.92, P = 0.002; stage II-III only: adjHR = 2.76, 95% CI, 1.23–6.20, P = 0.014]. There was high mutation load in pts carrying ATM/RB1 mutations (median mutation count: 196 versus 160, P = 0.09). In the validation (stage IV) dataset, ATM/RB1 mutations were present in 31.7% of pts and tended to associate with shorter OS (adjHR = 1.97, 95% CI, 0.89–4.40, P = 0.094) and higher mutation load (median mutation load: 8.1 versus 7.2 per Mb, P = 0.136), although statistical significance was not reached. Conclusions: These results suggest that ATM/RB1 mutations may be considered as a poor prognostic biomarker in unselected urothelial cancer pts and may correlate with higher mutational load. Further studies are required to determine patient characteristics that can further stratify prognosis based on ATM/RB1 mutation status, and evaluate the potential predictive role of ATM/RB1 mutation status in response to immunotherapy.

Cisplatin-based neoadjuvant chemotherapy (NAC) in bladder cancer patients (Pts) with borderline renal function: Implications for clinical practice

390

Background: Cisplatin-based NAC prior to cystectomy is a standard of care in muscle-invasive bladder cancer (MIBC). There are limited data for pts with borderline glomerular filtration rate (GFR) who get cisplatin-based NAC. Methods: A retrospective review of pts who received cisplatin-based NAC at Cleveland Clinic (2005-2016) was done. Pts with pre-NAC GFR of 40-59 mL/min by either CG or MDRD formula (low GFR group; n = 17) were compared to pts with GFR ≥ 60 (nl GFR group; n = 74) for treatment-related toxicities and outcomes, such as pathologic complete (pCR, pT0N0) and partial response (pPR, < pT2N0), overall survival (OS) and recurrence-free survival (RFS). Comparisons were made using Fisher’s exact, Wilcoxon, or log-rank tests. Results: Pts with low GFR were older (median age 69 vs 64, p = .02) with worse PS (44% vs 20% ECOG > 0, p < .05). Gender, race, hydronephrosis rates and TURBT features (stage, grade, LVI, CIS) did not differ. For NAC, 64 pts got Gem/Cis (49 normal GFR, 15 low GFR), 23 got MVAC (22 normal GFR, 1 low GFR), 4 got other. Low GFR pts were less likely to get MVAC (6% vs 30%, p = .08) and more likely to get split-dose cisplatin (38% vs 18%, p = .10) and have NAC modified (delayed, dose reduced or stopped) (69% vs 36%, p = .02). 4/17 pts (24%) with low GFR and 9/73 (12%) with normal GFR did not complete all planned NAC cycles (p = .26). Hematologic toxicity caused most dose delays but renal toxicity was the most common cause of NAC stoppage (4/9 normal GFR, 3/4 low GFR). NAC cycles completed (median 3 / group) and G-CSF use (31/61 normal GFR, 3/9 low GFR) were comparable. No difference was noted in time to cystectomy (mean 107 days for normal vs 103 days for low GFR from NAC start), surgical complications, length of stay, and either post-NAC or post-cystectomy GFR decline from baseline. Combined pathologic response (pCR/pPR) was higher in normal GFR pts (50% vs 18%, p = .02). OS and RFS at 2 years were 89% and 79% for normal GFR and 78% and 58% for low GFR. Conclusions: Low GFR pts were older with worse PS, had more NAC modifications, lower pCR/pPR and trend for shorter OS & RFS, but most completed planned NAC cycles. For very carefully selected pts with GFR 40-59, cisplatin-based NAC is a treatment option.

Relationship of smoking status to genomic profile, chemotherapy response and clinical outcome in patients with advanced urothelial carcinoma

Smoking has been linked to urothelial carcinoma (UC), but the implications on genomic profile and therapeutic response are poorly understood. To determine how smoking history impacts genomic profile and chemotherapy response, clinicopathologic data was collected for patients with metastatic UC (mUC) across 3 academic medical centers and comprehensive genomic profiling (CGP) was performed through a CLIA-certified lab. Unsupervised hierarchical clustering based on smoking status was used to categorize the frequency of genomic alterations (GAs) amongst current smokers (CS), ex-smokers (ES) and non-smokers (NS), and survival was compared in these subsets. Fisher's exact test identified significant associations between GAs and smoking status. Amongst 83 patients, 23%, 55% and 22% were CS, ES, and NS, respectively, and 95% of patients had stage IV disease. With a median follow up of 14.4 months, the median overall survival (OS) was significantly higher in NS and ES (combined) as compared to CS (51.6 vs 15.6 months; P = 0.04). Of 315 cancer-related genes and 31 genes often related to rearrangement tested, heatmaps show some variations amongst the subsets. GAs in NSD1 were more frequent in CS as compared to other groups (P < 0.001). CS status negatively impacts OS in patients with mUC and is associated with genomic alterations that could have therapeutic implications.

Evaluation of response to enzalutamide (E) consecutively after disease progression on abiraterone/prednisone (AP) and potential predictors of response

294

Background: Efficacy data of E immediately after AP failure in castrate resistant prostate cancer (CRPC) is limited. Although clinical cross-resistant has been observed, the optimal sequence of these agents is not defined. Specific patient pt) characteristics on AP could be useful in selecting appropriate pts for subsequent therapy with E. Methods: We retrospectively reviewed records of 40 pts with CRPC treated at the Cleveland Clinic with E immediately after disease progression on AP. We evaluated clinical / pathological features that could predict subsequent response or lack thereof to E. For this exploratory analysis, best % change in PSA (%Ch-PSA) was used as indicator of treatment response. Results: Median age at E initiation was 69 (58-81), median time from diagnosis to AP initiation was 6.1 years (0.9-16.3). Median PSA was 30.9ng/mL (1.5-1680) at the time of AP initiation and 66.9ng/mL (2.52-3130) at E initiation. 30/40 and 35/40 pts had bone metastasis at AP and E initiation, respectively. Prior treatments to AP included Ketoconazole (45%), Docetaxel (35%). Median time to PSA progression on AP was 9.6 m (0.5-49.6) and 2.3 m (1.8-3.1) on subsequent E. 26/39 pts on AP achieved PSA decline >25%; among these 20 had >50% PSA decline. Similarly, 13 and 8 pts receiving subsequent E achieved >25% and >50% PSA decline, respectively. 10/40 pts did not have PSA response with either agent. 4 pts had PSA decline > 50% on both agents. There was no significant correlation between %Ch-PSA on E and %Ch-PSA on AP, pre-E PSA, time to PSA progression on AP, or time from diagnosis to AP. Longer interval between AP and E initiation was associated with better outcome on E (p=.03). Prior treatment to AP did not predict subsequent response to E. Conclusions: Except for the association between longer interval between AP and E initiation with PSA response on subsequent E, other clinicopathological factors did not predict response to consecutive E in this cohort of pts. Identifying clinical and/or molecular factors predictive of response to AP and E in this setting is of critical importance. Ongoing randomized prospective studies will help determine the optimal treatment sequencing in men with CRPC.