Biomarkers of response to neoadjuvant atezolizumab with gemcitabine and cisplatin in muscle-invasive bladder cancer

4584

Background: We previously reported the clinical outcomes of a positive multi-center phase II trial of neoadjuvant gemcitabine (G) and cisplatin (C) plus atezolizumab (A) in patients with muscle-invasive bladder cancer (Funt, et al. JCO 2022). In this and another trial of neoadjuvant GC with pembrolizumab (Rose et al, JCO 2021), PD-L1 positivity by immunohistochemistry was not predictive of non–muscle-invasive downstaging ( < pT2N0). Therefore, we investigated other pre-treatment tissue-based genomic and gene expression biomarkers of response and resistance. Methods: 36 pts had pre-treatment tissue available for genomic analysis. We performed targeted hybridization capture DNA sequencing using the CLIA-certified MSK-IMPACT platform and whole transcriptome RNA sequencing. We examined genomic and gene expression biomarkers which have been previously investigated in the context of neoadjuvant cisplatin-based chemotherapy or anti-PD-1/L1 immunotherapy for MIBC, including tumor mutation burden (TMB), a DNA damage response (DDR) 9-gene panel (NCT03609216) associated with response to neoadjuvant chemotherapy, and an 8-gene cytotoxic T cell transcriptional signature associated with response to neoadjuvant A (tGE8; Powles et al, Nature Medicine 2019). We also evaluated TGF-β pathway activation, which was associated with resistance to A in pts with metastatic BC (Mariathasan et al, Nature 2018). Putative biomarkers were assessed for correlation with < pT2N0, the trial’s primary endpoint. Results: DNA was available from all 36 pts, and RNA met quality control metrics for 29 pts. TMB was significantly higher in pts with < pT2N0 (median 16 mut/Mb, IQR 12-25) versus ≥ pT2N0 (median 10 mut/ Mb, IQR 8-10; p < 0.01). A single patient had a TMB > 200 Mut/Mb with a POLE hotspot mutation and achieved pT0N0; TMB was still significantly higher in responders after omission of this patient (p < 0.01). Nine of 25 pts (36%) with < pT2N0 had a deleterious DDR mutation versus 1 of 10 pts (10%) with ≥ pT2N0 (p = 0.13). While tGE8 was significantly increased in patients with < pT2N0 compared to those without (p = 0.01), TGF-β pathway activation was not increased in pts with ≥ pT2N0 (p = 0.99). Conclusions: TMB and the tGE8 cytotoxic T cell transcriptional signature were associated with response to combination GC+A in muscle-invasive bladder cancer. More detailed molecular analyses will be reported. Clinical trial information: NCT02989584.

Association of DNA damage repair (DDR) mutations (mts) and clinical outcomes in CALGB 90601 (Alliance)

4521

Background: Platinum-based chemotherapy is the standard 1st-line therapy for metastatic urothelial cancer (mUC). C90601 was a randomized phase III trial testing gemcitabine and cisplatin (GC) with bevacizumab (B) or placebo (P) in patients (pts) with untreated mUC. Median overall survival (OS) for GCB vs GCP was 14.5 months (mo) vs 14.3 mo (p=0.14) and median progression-free survival (PFS) was 8 vs 6.7 mo, respectively. DDR mts have been implicated in response and survival in mUC and were investigated in this negative trial. Methods: C90601 enrolled 506 pts randomized 1:1 to GCB or GCP from 7/15/09-12/2/14, with stratification for prior chemotherapy and visceral metastases. Consenting pts submitted archival FFPE tumor specimens and blood for matched germline (g)DNA. Tumor and gDNA were sequenced by MSK-IMPACT, a 468-gene exon capture assay, to detect mts in select DDR genes. The proportional hazards model was used to correlate mts in the DNA helicase ERCC2 (pre-specified hypothesis) and additional DDR gene panels being explored in prospective trials in muscle-invasive disease with OS and PFS, adjusting for tumor mt burden and stratification factors. Mts were categorized as deleterious (del) or non-del using pre-defined published criteria. Results: 208 pts underwent DNA sequencing. Clinical features and PFS/OS were comparable to the 506-pt cohort. Median sequencing coverage was 497X. Median mutation count was 13.2 and 8.8 for DDR mt and wild-type tumors, respectively. A non-significant improvement in OS and PFS was seen in pts with ERCC2 mts (HR 0.70), but the 5.3% frequency of ERCC2 mts was lower than in historical series. Neither del mts (table) nor any mts in DDR genes were associated with PFS/OS. Conclusions: DDR mts were not associated with improved outcomes in C90601. The reliance on archival specimens, lower-than-expected ERCC2 mt frequency, small sample sizes, and tumor genomic heterogeneity may have influenced the predictive capacity of DDR mts in this cohort. Similar analyses are underway in pts who received neoadjuvant chemotherapy prior to cystectomy from completed prospective trials. Support: U10CA180821, U10CA180882, Genentech.[Table: see text]

Association between molecular subtype membership or hypoxia-associated gene expression signatures and clinical outcomes in the CALGB 90601 (Alliance) phase 3 clinical trial of gemcitabine and cisplatin (GC) plus bevacizumab (B) or placebo (P)

4562

Background: Our previous work showed that basal tumors were associated with the best clinical outcomes in a Phase 2 clinical trial of neoadjuvant dose-dense MVAC plus B, and in other work we showed that basal tumors were enriched with hypoxia-associated gene expression signatures. Here we attempted to validate these findings in the C90601 Phase 3 clinical trial of GC plus B versus GC plus P. Methods: Whole transcriptome RNAseq was performed on all available tumors using Ion Torrent’s Ampliseq platform (n = 189). Tumors were assigned to molecular subtypes using 3 different classifiers - BASE47 (k=2), MDA oneNN (k=3), and the Consensus classifier (k=6). Tumor hypoxia signature enrichment was determined using 2 different gene expression signatures and gene set variation analysis (GSVA). The proportional hazards model was used to correlate molecular subtype calls and hypoxia signature enrichment with overall survival (OS) and progression-free survival (PFS) adjusting for stratification factors and treatment arm (for PFS). Results: The median OS & PFS by different signatures and the hazard ratios (HR) are presented in the Table. Conclusions: Predefined signatures associated with clinical benefit in the Phase-2 neoadjuvant clinical trial were not associated with benefit in C90601. Possible explanations include the lack of strong therapeutic effects of the treatments, potential heterogeneity (“subtype plasticity”) between the profiled tissue samples and the metastatic lesions under treatment pressure, and differences in biology associated with the disease states (muscle-invasive vs advanced/metastatic disease). Support: U10CA180821, U10CA180882, Department of Defense (CA160312), Genentech; ClinicalTrials.gov Identifier: NCT00942331. [Table: see text]

Association of DNA damage response (DDR) gene mutations (mts) and response to neoadjuvant cisplatin-based chemotherapy (chemo) in muscle-invasive bladder cancer (MIBC) patients (pts) enrolled onto SWOG S1314

4522

Background: Neoadjuvant cisplatin-based chemo followed by radical cystectomy (RC) is a standard of care treatment for pts with MIBC. DDR gene mts, including within ERCC2, a DNA helicase implicated in cisplatin sensitivity in MIBC, have been associated with higher pathologic (path) downstaging ( < pT2) and complete response (pT0) at RC and improved overall survival (OS) in retrospective series. S1314 randomized pts to one of 2 chemo regimens (dose dense MVAC or Gem/Cis) followed by RC. We sought to correlate ERCC2 and other DDR gene mts with response and survival in MIBC pts enrolled onto this prospective trial. Methods: Tumor and matched germline DNA from evaluable pts enrolled onto S1314 underwent exon capture sequencing of 505 cancer-associated genes (MSK-IMPACT). Both deleterious (del) mts and any mts in 9 DDR genes (ERCC2, ERCC5, BRCA1, BRCA2, RECQL4, ATM, ATR, RAD51C, FANCC) were correlated with clinical outcomes. The prespecified analyses included the association of mts with < pT2 and pT0 by logistic regression analysis and with progression-free survival (PFS) and OS by Cox proportional hazards regression. Results: 179 patients (median 61 years, 85% male, 87% white, and 87% clinical stage T2) who received >2 cycles of chemo and were evaluable for path response were included in the analysis. The pT0 rate was 28% and < pT2 was 41%. Del mts in ERCC2 were detected in 26 (14%) pts followed by ATM (n = 12, 7%), ATR (n = 3) and BRCA2 (n = 2). ERCC2 mts were associated with statistically significantly higher path responses with a 54% pT0 rate and 62% downstaging rate. Patients with any del mts had higher path response rates (51% pT0, 56% < pT2) and better PFS (Table) with a median follow-up of 53 months. There was a non-significant trend towards improved OS. Conclusions: In pts managed with neoadjuvant chemo and RC on S1314, both ERCC2 mts and del DDR gene mts correlated with pathologic response. Any del DDR gene mt was associated with improved PFS. These results are in line with retrospective analyses displaying a correlation between DDR gene mts and neoadjuvant chemosensitivity in MIBC and support ongoing genomically-informed organ sparing trials.[Table: see text]

Neoadjuvant nivolumab (N) +/- ipilimumab (I) in cisplatin-ineligible patients (pts) with muscle-invasive bladder cancer (MIBC)

498

Background: Cisplatin-based neoadjuvant chemotherapy followed by radical cystectomy (RC) confers survival benefit but a substantial subset of MIBC pts are cisplatin-ineligible. We conducted a phase II trial of N±I neoadjuvant therapy for cisplatin-ineligible MIBC. Methods: Cisplatin-ineligible pts with MIBC (cT2-T4aN0M0) were enrolled into 2 consecutive cohorts of 15 pts each (C1: N 3 mg/kg q 2 weeks (wk) x 5; C2: I (3mg/kg) + N (1mg/kg) wk 0 and 6, with N (3mg/kg) wk 3 and 9). A 3rd cohort was planned (C3: I (3mg/kg) + N (1mg/kg) q 3 wk x 3). Primary endpoint (EP) was eligibility for planned RC within 60 days without delay from treatment-related adverse events (TRAEs) or progressive disease (PD). Secondary EPs included pathologic downstaging (PaDo, <ypT2pN0) and complete response (pCR, ypT0pN0) rates, recurrence-free survival (RFS), and safety. Exploratory EP was event-free survival (EFS). Results: From 8/2018-5/2021, 15 pts were enrolled onto C1 and C2 (N = 30). Median age 76 (range 53-87), 80% male, with median Charlson comorbidity score of 1 (range 0-5). In C1 and C2, 14/15 and 6/15 pts received all planned treatment, respectively. In C2, 7/15 received ≤ 50% of planned doses. In C1, 11 pts underwent RC, 2 had PD before RC, 1 did not undergo RC due to TRAE, and 1 declined RC. Overall, 12/15 met the primary EP. For C2, 9 pts underwent RC, 3 had PD before RC, 2 did not undergo RC due to AE (1 of which was TRAE), and 1 opted for radiation, with 8/15 meeting the primary EP. C3 was dropped due to C2’s failure to meet the primary EP. In C1, 4 pts had PaDo (26%), with 2 pCRs (13%). In C2, 3 pts had PaDo (20%), with 1 pCR (7%). In C1, 1 pt who did not undergo RC due to TRAE had clinical CR of 13.2 months (mos) but died of sepsis at 16.1 mos; 2 pts in C2 who did not undergo RC have ongoing clinical CR at 16.1 and 10.8 mos follow-up (f/u). For time-to-event EPs, see Table. In C1, the only observed grade 3-4 TRAE was myocarditis (n=1, 7%). In C2, 4 pts (27%) had grade 3-4 TRAE, including elevated lipase (20%), pneumonitis (13%), fatigue (13%), and elevated AST + ALT(13%). Median tumor mutation burden was 8.8/megabase; DNA damage response genes were altered in 31% of pts and FGFR3 in 14%, with no genomic correlation with PaDo. For C1, 4/10 had baseline PD-L1 expression on ≥1% of tumor cells; 1 had PD-L1 ≥5%. Conclusions: In this cohort of cisplatin-ineligible pts with MIBC and comorbidities, neoadjuvant N was well tolerated. N+I was associated with greater toxicity resulting in RC delays. Pathologic response rates were low in both cohorts, raising questions about utility of treatment intensification in cisplatin-ineligible patients. Some pts who did not undergo RC due to TRAEs had sustained clinical CR. Clinical trial information: NCT03520491. Clinical trial information: NCT03520491. [Table: see text]

Incidence and clinical outcomes of HER2-altered bladder cancer (BC) patients (pts)

556

Background: Bladder cancer has one of the highest rates of human epidermal growth factor receptor 2 (HER2) alteration. Novel HER2-directed agents are being investigated in metastatic BC. We sought to define the incidence and clinical characteristics of HER2-altered BC across disease states. Methods: We retrospectively analyzed our single-institution, clinically annotated cohort of urothelial BC pts with available genomic profiling data (MSK-IMPACT). We quantified the prevalence of HER2 alterations, defined as driver mutation (based on OncoKB), and/or amplification, across BC disease states. We examined the association between HER2 alteration and disease progression and survival. The Kaplan-Meier method was used for time-to-event analyses. Results: A total of 1073 BC pts underwent MSK IMPACT profiling of tumor tissue derived from the following disease states: 36% (n = 380) non-muscle invasive (NMI)BC, 41% (n = 443) muscle invasive (MI)BC, and 23% (n = 250) (met)BC. At initial diagnosis, the median age was 67 years, 77% (n = 822) were male, 86% (n = 928) were white, and 66% (n = 710) were smokers. Overall, 16% (n = 177) of pts had any oncogenic HER2 alteration (Table), including 11% with a HER2 driver mutation and 7% with HER2 amplification The most frequent mutations were S310F (40%, n = 53) and S310Y (14%, n = 19). The rate of HER2 amplification was different among the three groups (p = 0.002), 9% in MIBC and metBC compared to 3% in NMIBC. Among 514 pts with NMIBC, the median time to progression (TTP) to MIBC or metBC was 111.6 months (95% Cl: 85.7-NR). Among NMIBC pts, TTP was significantly shorter for HER2-amplified (n = 17) vs. non-amplified (n = 497) (HR = 1.99, 95%CI: 1.05-3.76, p = 0.034, median 26 vs. 114 months). Among pts with metBC receiving frontline platinum-based chemotherapy (n = 143), the median overall survival (OS) was 25.3 months (95%CI: 18.5-33.9). OS was numerically higher in pts with any oncogenic HER2 alteration (n = 26) compared to wild-type (n = 117) (HR = 0.59, 95% Cl: 0.33-1.07, p = 0.082), though this difference was not statistically significant. The median OS for platinum-refractory metBC pts receiving 2nd line immunotherapy (n = 63) was 10.3 months (95%CI: 7.2-31.6), and the association between OS and HER2 alteration was not significant (HR = 0.57, 95%CI: 0.24-1.37, p = 0.2). Conclusions: HER2 amplification is more frequent in MIBC and metBC than in NMIBC. In NMIBC, HER2 amplification is associated with shorter TTP to MIBC or metBC. HER2 alteration in metBC is associated with a non-significant trend towards improved OS in frontline platinum-treated pts, though this analysis is limited by small sample size.[Table: see text]

Pretreatment Eosinophil Counts in Patients With Advanced or Metastatic Urothelial Carcinoma Treated With Anti-PD-1/PD-L1 Checkpoint Inhibitors

Eosinophils influence antitumor immunity and may predict response to treatment with immune checkpoint inhibitors (ICIs). To examine the association between blood eosinophil counts and outcomes in patients with advanced or metastatic urothelial carcinoma (mUC) treated with ICIs, we identified 2 ICI-treated cohorts: discovery (n=60) and validation (n=111). Chemotherapy cohorts were used as comparators (first-line platinum-based chemotherapy, n=75; second-line or more pemetrexed, n=77). The primary endpoint was overall survival (OS). Secondary endpoints were time on treatment (ToT) and progression-free survival. Univariate and multivariate analyses were performed using Cox proportional hazard models. Associations between changes in eosinophil count at weeks 2/3 and 6 after the start of ICI treatment were analyzed using landmark analyses. Baseline characteristics of the ICI cohorts were similar. In the discovery cohort, an optimal cutoff for pretreatment eosinophil count was determined [Eos-Lo: <100 cells/µL; n=9 (15%); Eos-Hi: ≥100 cells/µL; n=51 (85%)]. Eos-Lo was associated with inferior outcomes [OS: hazard ratio (HR), 3.98; 95% confidence interval (CI), 1.85-8.56; P<0.013; ToT: HR, 2.45; 95% CI, 1.17-5.10; P=0.017]. This was confirmed in the validation cohort [Eos-Lo: n=17 (15%); Eos-Hi: n=94 (85%)] (OS: HR, 2.51; 95% CI, 1.31-4.80; P=0.006; ToT: HR, 2.22; 95% CI, 1.2-3.80; P=0.004), and remained significant after adjustment for other prognostic factors. Changes in eosinophil counts at weeks 2/3 and 6 were not clearly associated with outcomes. In chemotherapy cohorts, eosinophil counts were not associated with outcomes. In conclusion, low pretreatment eosinophil count was associated with poorer outcomes in patients with mUC treated with ICIs, and may represent a new predictive biomarker.

Real-time data quality assurance analysis for real-world, pan-cancer data

e18775

Background: The production of high-quality real-world data requires comprehensive and meticulous data quality assurance (QA) methods to guarantee that adequate standards of accuracy, completeness, and consistency are met. Memorial Sloan Kettering Cancer Center (MSKCC) synthesizes manually curated Electronic Health Record (EHR) data to collect and harmonize the fundamental data elements across all cancer types. Centralized real-time analysis of curated data quality can allow for rigorous review to identify areas of strength and opportunities for improvement in the curation process. Methods: MSKCC built the Core Clinical Data Element (CCDE) data model, which encompasses aspects of PRISSMM, ASCO’s mCODE, and NAACCR tumor registry frameworks, to capture standardized real-world, pan-cancer, pan-specialty data across 11 modules, including cancer genomics, imaging, pathology, surgery, and radiation. A key component within the QA process is source data verification (SDV), the comparison of curated data against source documents to identify inconsistencies. Any discrepancies detected are classified into major and minor violations. Major violations are errors or omissions on core data elements that would impact time interval calculations, such as an incorrect procedure date. Minor violations are errors or omissions on less critical data elements, such as a missing radiation therapy dose. Identifying these inconsistences allows the QA team to recognize patterns in curation errors and distinguish areas for curator retraining. Results: With limited functionality in basic standard data quality checks that exist across various data storage platforms, an interactive application was developed using the R Shiny package to access data as cases are recorded and summarize findings from SDV in real time. The app has two panels, each stratified by CCDE module. The first panel details the total number of forms curated and percentage of forms that underwent SDV, with each form representing one of the 11 modules. The other panel consists of a set of tables that summarize specific major and minor violations based on user selection of a denominator of either patients (e.g. how many patients had a violation on at least one imaging report) or forms (e.g. how many imaging reports had a violation). We will demonstrate the utility of the app and discuss benefits of real time evaluation in large-scale, real-world EHR curation efforts. Conclusions: We recommend automated, user-friendly tools to assess data quality of such efforts. With real-time analysis, the tool allows for ongoing and regular data checks, enabling clarification of directives and retraining of curators as necessary early in the curation process. As the data curation efforts expand to more cancer cohorts, the app examines data quality of each cohort to ensure consistent evaluation. This offers transparency of data quality to ensure usability in real-world data for rigorous research.

Detection of FGFR3 alt in plasma cfDNA in metastatic UC patients receiving Erda therapy

e16519

Background: The pan-FGFR inhibitor erdafitinib (erda) is FDA-approved for pretreated mUC pts harboring FGFR2/3 alterations. We explored concordance of FGFR3 alt profiles between primary tumor and cfDNA using the next generation sequencing assay MSK-ACCESS. We also correlated changes in FGFR3 cfDNA mutant allele fraction (MAF) with response to erda. Methods: After consent on an approved biomarker protocol, plasma samples were collected from mUC pts on erda at baseline, on treatment (tx), and at progression along with patient clinical characteristics. Baseline tumors were sequenced with MSK-IMPACT and plasma samples sequenced with MSK-ACCESS, a cfDNA platform that sequences select exons and introns of 129 genes and uses unique molecular indexes to detect somatic mutations down to 0.1% MAF. Results: Between 8/2019-12/2020, 18 pts started erda 8mg daily and had plasma drawn for MSK-ACCESS. Three pts increased to 9mg daily, 7 required dose reductions and 10 had dose interruptions. Treatment was discontinued in 13 pts for disease progression and 3 for toxicity. Median PFS was 3.7 months. FGFR3 S249C was the most frequent alt detected (11/18, 61%), then Y373C (3/18, 16%), and R248C (2/18, 11%) (Table). FGFR3 alt were detected in 15/18 (83%) baseline plasma samples, all of which were of the same alt as tumor tissues. In 3 samples, additional FGFR3 alt were detected, including 1 pt with an FGFR3-TACC3 fusion and hotspot mutations found only in cfDNA. FGFR3 MAF decreased in 7 of 9 pts on erda, 2 of whom declined to undetectable levels. Conclusions: A high degree of concordance of FGFR3 alt was observed between primary tumors and cfDNA. Most erda responders displayed reduction of FGFR3 cfDNA MAF. FGFR3 alts exclusive to cfDNA were found in a small subset of pts. Further pt accrual and follow-up are ongoing to assess for correlations between erda response/progression and changes in FGFR3 cfDNA MAF, and to assess whether cfDNA can identify resistance mechanisms.[Table: see text]

Assessment of cancer-specific microbiome signature of response to immune checkpoint inhibitors

2574

Background: Clinical and preclinical experiments suggest that the gut microbiome can affect outcome in cancer patients treated with immune checkpoint inhibitors (ICI). Most data to date has been in melanoma, so the relationship of the gut microbiome with treatment outcome in other cancers is poorly understood. Here, we evaluated the microbiome composition in correlation to ICI response in patients with metastatic lung, urothelial, or renal cancer, as well as metastatic melanoma. Methods: Fecal microbiome samples were obtained from patients with metastatic melanoma, lung, urothelial, or renal cancer immediately before ICI therapy was initiated. Bacterial genomic DNA was isolated and profiled by whole metagenome sequencing. Sequence data were analyzed using a custom implementation of MetaPhlAn2. Response to ICI was defined as partial or complete response or remaining on therapy for more than 6 months. Results: Samples were prospectively collected from 94 patients, including metastatic melanoma (n = 17), lung (n = 44), urothelial (n = 23), or renal cancer (n = 10). Treatment included anti-PD(L)1 monotherapy (n = 51), anti-PD1 + anti-CTLA4 combination therapy (n = 17), or a combination of anti-PD1 and chemotherapy (n = 26). Clinical response was observed in 58% of patients, including partial or complete response (45%) and on treatment for more than 6 months (55%, with 31% on treatment for more than 1 year). Although the variance in the composition of pretreatment microbiome samples did not explain response alone (R vs NR, PERMANOVA, p = 0.273), a significant portion of the variance in microbiome composition was explained by the interaction of cancer type and outcome (PERMANOVA, p = 0.014), suggesting a cancer-specific microbiome relationship. Notably, there was some similarity in the signature of NR across three cancer types (lung, urothelial and melanoma). One sample in this NR cluster was from a patient whose metastatic NSCLC was nonresponsive to pembrolizumab and carboplatin/pemetrexed. This microbiome sample was evaluated in vivo using subcutaneous MC38 and CT26 tumor models in germ-free mice. In contrast to mice colonized with stool from a healthy donor, mice colonized with stool from this patient yielded a nonresponsive result upon treatment with anti-PD1 or anti-PD-L1 in combination with anti-CTLA4. Conclusions: Analysis of the fecal microbiome composition from patients with metastatic lung, urothelial, renal cancer, and melanoma identified a cancer-specific signature of R and NR to ICI. Across three cancer types, a consistent signature of NR was identified and corroborated experimentally in preclinical models.

Enfortumab vedotin in FGFR3-mutated advanced urothelial carcinoma

458

Background: Enfortumab vedotin (EV) and, for those with FGFR3 mutations (FGFR3+), erdafitinib, are established therapeutic options for refractory advanced urothelial carcinoma. However, optimal sequencing of these agents remains undefined. Here, we report our experience of EV monotherapy with focus on patients (pts) with FGFR3 alterations. Methods: Pts who were treated with EV were identified. Clinical data and outcomes were extracted. Tumor genomic profiles by the MSK-IMPACT assay as part of standard of care were reviewed for FGFR3 and other commonly altered gene mutations and tumor mutation burden (TMB). Progression-free (PFS) and overall survival (OS) were measured from start of EV therapy and compared with unadjusted log-rank test. Results: 89 patients received EV on completed monotherapy studies (n = 37) or as standard of care. Median age was 62 years (IQR: 62 – 78), 71% were male (n = 63), 28% had liver metastases. Distribution per Bellmunt score (0 – 3) was: 12%, 42%, 37% and 9%. For the entire population, PFS and OS were 5.2 and 11.4 months, respectively, with response rate of 52% among 75 evaluable patients. MSK-IMPACT was available for 80 patients. Overall genomic profile was similar to TCGA cohort except for fewer DNA damage response/repair gene alterations – 15% (ERCC2: 2; ATM: 4, BRCA1: 2, BRCA2: 3, RAD51C: 1) and FGFR3+ rate of 33%. Median TMB was 8.9/Mb (IQR: 5.2 – 13.3). Of the 26 FGFR3+ pts, 8 and 1 received an FGFR3 inhibitor (FGFR3i) before and after EV, respectively. 17 pts have not been exposed to FGFR3i; 13 of whom have progressed on EV and 9 died. Compared to FGFR3- pts, FGFR3+ pts with no prior FGFRi had significantly shorter median PFS on EV (2.5 vs. 6.8 months; HR 0.33 [0.14 – 0.80] p < .01) and trend towards shorter median OS (4.9 vs. 14.6 months; HR 0.42 [0.16 – 1.08] p > .05). PFS on EV among FGFR3+ pts with prior FGFR3i exposure was 6.7 months, similar to FGFR3- pts (HR 0.77 [0.30 – 1.96] p = .6). Response rates for FGFR3+ with and without prior FGFRi, and FGFR3- pts on EV were 4/7 (50%), 5/13 (38%) and 29/48 (60%). Conclusions: In this retrospective study, FGFR+ patients who receive EV first appear to have shorter PFS and lower ORR than those who have received prior FGFRi. Prospective studies on the sequence of EV and FGFR3i in FGFR3+ pts are warranted.

Interrogation of neoantigen-specific CD8 T cells in peripheral blood following PD-L1 blockade in patients with metastatic urothelial carcinoma (mUC)

3075

Background: Proliferation of CD8 T cells can be detected in the blood of cancer patients (pts) following a single dose of immune checkpoint blockade (ICB) and tends to be more robust in responding pts. Furthermore, tumor mutational burden (TMB) is seen to predict outcome to ICB across cancers. Mutation-derived neoepitopes presented on the tumor cell surface is believed to be recognized by T cells and are thus critical for tumor clearance. However, the capacity to mount a neoantigen T cell response and the kinetics in relation to ICB remain poorly understood. Methods: 24 pts with mUC were treated with atezolizumab (anti-PD-L1) 1200mg q3w on IMVigor 210 at MSKCC and included in here. Pt-specific neoepitopes were predicted based on whole-exome and RNA sequencing of pre-treatment archival tumors using the MuPeXI platform. Using DNA-barcode labelled pMHC multimers, we investigated CD8 T cell recognition of mutation-derived neoepitopes by screening pt PBMC samples pre- and post-treatment with atezolizumab (n = 85 PBMC samples). The kinetics of neoepitope-specific CD8 T cells were assessed for association with durable clinical benefit (DCB; defined as progression free survival > 6 mo). Results: Neoepitope peptide libraries of between 200-587 peptides were generated per pt (mean = 260 peptides per pt). 31 out of a combined 56 possible pt HLA types across the cohort were utilized for T cell analyses (mean four HLAs per pt). MHC multimer-based screening of pt PBMCs revealed detection of neoepitope-specific CD8 T cells in 22 of 24 pts pre-treatment (range one to 14 neoepitope responses) and 21 of 22 pts post-treatment (up to 273 weeks after trial start; one to 19 neoepitope responses). There were large inter- and intra-patient variations of neoepitope-specific CD8 T cell responses during treatment with the largest increases occurring at the 3-wk, post-treatment initiation timepoint. We observed that pts with DCB tend to raise a broader neoantigen T cell response than patients without DCB. 38% of pts without DCB and 67% of pts with DCB exhibited an increase in neoepitope-specific CD8 T cell responses within 3 wks of treatment initiation. Conclusions: Using high-throughput screening, pt-specific neoepitope reactive CD8 T cells could be detected pre- and post-treatment in pts with mUC treated with atezolizumab. Phenotypic characterization of neoepitope reactive CD8 T cells is ongoing. These data may help elucidate the dynamics and characteristics of the T cells of highest relevance to the ICB-induced, anti-tumor immune response.

MSK-ACCESS for the detection of fibroblast growth factor receptor-3 (FGFR3) mutations in plasma cell-free (cf)DNA of metastatic urothelial carcinoma (mUC) patients (pts) pre- and on erdafitinib (erda) therapy

e17034

Background: The pan-FGFR inhibitor erda was recently FDA-approved for pretreated mUC pts harboring FGFR2/3 alterations. We explored concordance of FGFR3 mutation profiles between the primary tumor and cfDNA using the MSK-ACCESS platform. We also correlated changes in FGFR3 cfDNA mutant allele fraction (MAF) with response to drug. Methods: Plasma samples were collected from mUC pts started on erda at baseline, on treatment (tx), and at progression. Demographic and clinical characteristics were obtained. Baseline tumors were sequenced with MSK-IMPACT (ref) and plasma samples were sequenced using MSK-ACCESS, a cfDNA platform that sequences 129 genes using unique molecular indexes to generate > 15,000x coverage and detection of somatic mutations down to 0.1% MAF. Results: Between 08/2019-1/2020, 11 pts received erda 8mg daily. Of these, 3 pts increased dose to 9mg daily based on phosphorus level, 4 required dose reductions and 6 dose interruptions. In 5 pts, erda was discontinued for disease progression. FGFR3 S249C was the most frequent alteration detected (64%) followed by Y373C (18%), R248C and S371C (both 9%). Pre-treatment plasma FGFR3 profiles were concordant with tissue in 91% (10/11) of pts and additional FGFR3 mutations were detected in 3 cases (27%, Table), including 1 pt with an FGFR3-TACC3 fusion and hotspot mutations only in cfDNA. In 2 responding pts, the mutant allele was undetectable on erda. Conclusions: A high degree of concordance between primary tumor and cfDNA FGFR3 mutation detection was observed. FGFR3 mutations exclusive to cfDNA were found in a subset of pts. Further pt accrual and follow-up are ongoing to assess for correlations between erda response and tx-related changes in cfDNA MAF, and to assess whether cfDNA can identify resistance mechanisms. [Table: see text]

Clinicogenomic predictors of extreme responses to anti-PD1/PDL1 checkpoint inhibitors (CPI) in metastatic urothelial cancer (mUC)

5050

Background: Only a subset of mUC patients (pts) derives benefit from CPI. We sought to evaluate potential clinical and genomic predictors, with additional focus on extreme outcomes. Methods: CPI-treated mUC with tumor sequencing with MSK-IMPACT (up to 468 genes) were identified. Pre-CPI clinical variables (including hemoglobin [hgb], lymphocyte [lymph], neutrophil [neut] and eosinophil [eos] counts) were extracted. Endpoint was time on treatment (ToT). Poor responders were defined as ToT ≤9 weeks and overall survival ≤3 months; exceptional responders had ToT >20 months. A multivariate Cox model for ToT was performed with clinical variables chosen by stepwise selection minimizing Akaike information criterion. Genomic analyses were adjusted for multiple testing. Results: 166/171 identified mUC were evaluable. Median age was 68 years, 78% were male. 72% had bladder primary, while 17%, 35% and 28% had liver, lung and bone metastases (mets). 67% had prior platinum chemo. 24 pts (14%) were poor and exceptional responders, respectively. In univariate analysis, liver mets were associated with shorter ToT while DNA damage repair (DDR) gene alterations, higher body mass index (BMI), eos, hgb and tumor mutation burden (TMB) were associated with longer ToT. No specific genomic alterations achieved q<.05. In multivariate model, prior chemo (HR 1.6, p=.01), liver mets (HR 2.4, p<.01) and high neut were associated with shorter ToT while urethral primary (HR 0.1, p<.01), higher TMB (HR 0.9, p<.01) and higher eos (HR 0.1, p<.01) were independently associated with ToT. Univariate logistic regression to identify poor and exceptional responders are tabulated. Multivariate results will be reported. Conclusions: In addition to validation of various known mUC prognosticators, we observed potential non-linear influence of clinical and genomic factors on extreme outcomes. [Table: see text]

A phase II trial of durvalumab (MEDI4736) and tremelimumab in metastatic, nontransitional cell carcinoma of the urothelial tract

514

Background: Non-transitional cell carcinoma of the urothelial tract (non-TCC) includes several distinct histologies and is associated with a poor prognosis. Prospective data regarding management of patients with metastatic non-TCC is scarce. In this single-arm, phase II study, we assessed the activity and safety of durvalumab and tremelimumab in patients with metastatic non-TCC (NCT03430895). Methods: Eligible patients had unresectable/metastatic non-TCC with ECOG PS 0-1 regardless of prior therapy (except for patients with small cell carcinoma who must have progressed after chemotherapy). Patients received treatment with durvalumab 1500 mg and tremelimumab 75 mg IV Q4W for up to 4 cycles, then durvalumab 1500 mg IV Q4W for a total treatment duration of 12 months. The primary endpoint was overall response rate by RECIST 1.1. The study was planned as a Simon’s minimax two-stage design, with 13 patients planned for stage 1. If 1 or more responses were seen in stage 1, an additional 14 patients were planned to be accrued for a total of 27. Results: Thirteen patients were treated (median age 57 years; range, 33-76), including 7 (54%) with small cell carcinoma, 3 (23%) with squamous cell carcinoma, and 3 (23%) with adenocarcinoma. 11 patients (85%) had visceral metastases, and 6 patients (46%) had liver metastases. The study was terminated after stage 1 as no responses were seen; 11 patients (85%) had PD and 2 patients (15%) had SD as their best response. Median PFS was 1.8 months (95% CI 1.25, not reached [NR]) with a median follow-up of 6.8 months (range 4.3 – 18.1 months). Median OS was 6.43 months (95% CI 4.36, NR). Grade 3-4 treatment-related adverse events occurred in 31% of patients. Conclusions: In this poor prognosis cohort of patients with non-TCC, no responses were seen with durvalumab and tremelimumab. Immune correlative studies to help determine mechanisms of resistance will be presented. Novel therapeutic strategies are urgently needed for patients with metastatic non-TCC. Clinical trial information: NCT03430895.

Microsatellite instability (MSI-H) in metastatic urothelial carcinoma (mUC): A biomarker of divergent responses to systemic therapy

566

Background: MSI frequently arises from deficiencies in mismatch repair mechanisms (dMMR) and are associated with higher response rates to anti-PD1/PDL1 checkpoint inhibitors (CPI) in different cancer types, including mUC (Iyer et al, ASCO 2017). Here, we sought to (1) assess the platinum-based chemotherapy response in MSI-H mUC, and (2) present an updated analysis of CPI response in MSI-H mUC from a database of > 1000 sequenced UC. Methods: From an institutional database of UC tumors genomically characterized using the MSK-IMPACT assay, we identified tumors with high MSIsensor score > 10 (MSI-H) for in-depth analysis. MSIsensor has been shown to correlate strongly with MSI status (Middha et al, JCO Precis Oncol 2017). Patient and disease characteristics, as well as response to (1) platinum-based chemotherapy and (2) CPI were analyzed. Results: A total of 1,333 UC from 1,194 pts were sequenced. 26 pts (2%) had an MSI score > 10. Of these, 20 (77%) were male, 17 (65%) were current or former smokers, and 20 (77%) had upper tract UC. 23/26 pts had alterations in MMR genes (MSH2, n = 15; MLH1, n = 6; MSH6 and PMS2, n = 1), 18 of which underwent germline testing which was positive in 14 cases (78%). 10/26 MSI-H patients developed metastatic UC. Six received first-line platinum-based chemotherapy with median PFS of 2.6 months, four with primary progressive disease. Ten patients received CPI in the mUC setting, two of them in combination with non-CTLA4 agents, six as second or third-line therapies, two following recurrence of disease within 12 months of peri-operative chemotherapy, and two as first line therapy. With a median follow-up of 24.3 months, PFS rate was 90% and 77% at 12 and 24 months, respectively, with near-complete or complete response in 9 patients. Conclusions: MSI-H status in UC predicts deep and durable responses to CPI and is associated with inferior chemotherapy responses. CPI should be considered for first-line treatment in this subset of patients. Pts with somatic MSI-H bladder or upper tract UC should be offered genetic testing for Lynch syndrome.

Marker lesion study of oral FGFR inhibitor BGJ398 in patients with FGFR3-altered intermediate-risk nonmuscle-invasive bladder cancer

510

Background: FGFR3 alterations are prevalent in non-muscle-invasive bladder cancer (NMIBC). We conducted a marker lesion study of the oral FGFR inhibitor BGJ398 in patients with intermediate-risk NMIBC. Methods: Patients with recurrent clinical high-grade papillary NMIBC following intravesical BCG were eligible. FGFR3 alteration status was determined via testing of pre-treatment or archival tumor tissue. BGJ398 was administered at 125 mg PO daily for a 3 week on, 1 week off schedule (1 cycle). Response was determined after 2 cycles (at 7 weeks). Patients with a complete response (CR) had the option to continue therapy. Results: We enrolled four patients on trial, which we closed secondary to low accrual. Three patients had a CR at the 7-week evaluation. The other patient had a smaller, necrotic lesion after prematurely discontinuing treatment at 4 weeks. Clinically significant toxicities included eye disorders, skin and nail disorders, and elevations in LFTs. Two patients required dose reductions for toxicities. Two patients discontinued treatment before the 7-week evaluation, one for Grade 2 skin toxicity and the other for Grade 3 LFT elevation. All other toxicities were Grades 1 and 2. The other two patients continued treatment beyond a CR at 7 weeks but stopped after 3 and 4 cycles (after 11 and 16 weeks) for vision/skin toxicities and nail infection/mucositis, respectively. Conclusions: The oral FGFR inhibitor BGJ398 showed antitumor activity in a marker lesion study of patients with recurrent high-grade papillary NMIBC. Treatment was discontinued secondary to toxicities in all subjects, after a range of 4 to 16 weeks. Further investigation may be warranted for lower doses of oral BGJ398 or other formulations, such as intravesical delivery. Clinical trial information: NCT02657486. [Table: see text]

A pilot safety study of gemcitabine and cisplatin (GC) with atezolizumab (A) as first-line therapy in patients (pts) with metastatic urothelial cancer (mUC)

4559

Background: GC has a high overall response rate (ORR) but a high relapse rate in pts with untreated mUC. Inhibition of programmed death-ligand 1 (PD-L1) with A can lead to long-term survival, but single-agent ORR is modest. We report the outcomes of GC+A in a cohort pts with mUC. Methods: This study was designed to assess the safety of GC + A in 10 pts with untreated mUC prior to testing GC + A in a neoadjuvant study in pts with muscle-invasive disease. The primary endpoint was safety as assessed by a predefined dose limiting toxicity (DLT) rate during the first cycle in the first 6 pts. Total accrual goal was 10 pts to collect preliminary data on ORR and progression-free survival (PFS). RECIST 1.1 assessments were performed every 9 wks. Pts received 6 cycles of GC + A induction and then A maintenance every 3 wks. Results: No DLTs occurred during the first cycle in the first 6 pts. Grades 3-4 neutropenia and anemia occurred in 6/10 and 7/10 pts, respectively. Three pts required gemcitabine dose reductions for hematologic toxicity and 2 pts had febrile neutropenia. One pt discontinued cisplatin after 2 cycles for grade 3 hearing impairment but completed induction with gemcitabine and A. Only 1 pt discontinued study therapy due to treatment-related adverse events (AEs), including A-related grade 4 encephalopathy and grade 3 polyneuropathy. Three of 10 pts had visceral (liver or bone) metastases. Of the 10 pts, 1 pt is completing induction but meets initial criteria for partial response (PR), 8 pts had confirmed PR, and 1 pt had progressive disease (PD). Of 9 pts with confirmatory scans, the median PFS was 10.6 months (95% CI 6.7, N/A). Of 8 pts with confirmed PR, 5 eventually had PD, 1 has just completed induction, 1 remains without PD at 25 months, and 1 had consolidation surgery with a pathologic complete response and remains disease-free at 21 months. Conclusions: This 10 pt study met its primary safety endpoint. The neoadjuvant study is ongoing (NCT02989584). Although there were a substantial number of grade 3-4 toxicities, therapy was discontinued due to treatment-related AEs in only 1 pt. Immune correlative studies are ongoing. Clinical trial information: NCT02989584.

Invasive urothelial cancer (iUC) with FGFR3 hotspot mutation/fusion (FGFR3+): A molecularly and clinically distinctive entity?

459

Background: FGFR3+ is ubiquitous in non-invasive UC but found in ~16% of iUC. We sought to characterize the genomic landscape and response to platinum-based chemotherapy (ctx) of FGFR3+ iUC in the neoadjuvant (NAC) and metastatic (mUC) setting. Methods: Two molecularly-characterized cohorts were used for the study objective: (1) NAC-treated muscle invasive UC, incorporating consecutively sequenced standard of care UC and patients (pts) from a phase II trial (Iyer et al, JCO 2018); (2) mUC treated with platinum ctx, with FGFR3- mUC from a published work (Teo et al, CCR 2017) serving as comparator. iUC with hotspot mutations / fusions were considered FGFR3+. Clinical outcomes and frequency of altered genes were compared. Results: In the NAC cohort, 87 pts were identified (NAC response: pT0 [n = 20, 23%], <pT2 [n = 22, 25%], ≥pT2 [n = 45, 52%]). FGFR3+ (n = 11, 13%) was associated with a trend towards poor NAC response and was found in 0/20 pT0 (0%), 3/22 <pT2 (14%) and 8/45 ≥pT2 (18%) (Cochran-Armitage, p=0.06). Among ≥pT2 tumors, FGFR3+ was associated with shorter recurrence-free survival (3.7 vs 17.6 months; HR 4.8 95% CI 1.9–12.1). 49 FGFR3+ mUC pts were identified and compared to FGFR3- mUC (n = 82). FGFR3+ had a numerically higher rate of lung metastasis (42% vs 29%, p = 0.25). 1st line therapies included: platinum-based ctx (n = 27), non-platinum ctx (n = 4), immunotherapy (IO, n = 13), ctx + IO (n = 4), and FGFR inhibitor (n = 1). Platinum ctx response rate for 21/27 evaluable FGFR3+ pts was 40%. FGFR3+ mUC had similar overall survival (OS, median 25.7 vs 15.8 months, HR 0.7, 95%CI 0.4-1.2; 1-year OS: 70% vs 59%) and progression-free survival (median: 7.2 vs 7.1 months, HR 1.3, 95% CI 0.8-2.1). Frequencies of altered genes are tabulated. No differences in mutational load were seen. Conclusions: FGFR3+ iUC is a genomically distinct subset of iUC. Despite low responses to NAC ctx, FGFR3+ had similar responses, PFS, and OS in the mUC setting. [Table: see text]

Muscle invasive bladder cancer (MIBC) demonstrates neoadjuvant cisplatin-based chemotherapy (NAC) related changes in molecular subtype and immune infiltration

443

Background: Defining the role of MIBC molecular subtypes and immune expression in determining clinical outcomes is an area of active investigation. However, changes in these transcriptomic profiles pre- and post-NAC have not been well characterized. Methods: This retrospective study reviewed 53 pts with MIBC treated with NAC, of whom 12 pts without complete pathological response had both pre- and post-NAC samples of sufficient quality. Post-NAC staging was > = pT2 in 11 pts and pT1 in 1 pt. We performed RNA expression analysis of matched pre-NAC transurethral resection of bladder tumor specimens and post-treatment radical cystectomy primary bladder tumor specimens. We used a customized NanoString panel incorporating previously reported immune signatures (Ayers, JCI 2017; O’Donnell, ASCO 2017) and additional genes to assign basal ( CD14, CD44, PDGFC, KRT14, KRT5) and luminal ( GATA3, PPARG, SHH, CD24, FOXA1, WNT7B, ERBB2) molecular subtypes. Results: We first classified the bladder cancer cohort of The Cancer Genome Atlas into basal and luminal subtypes using the BASE47 signature (Damrauer, PNAS 2014) and the NanoString panel and there was good agreement (Rand Index = 0.72). We then assigned subtypes using the NanoString panel on matched pre- and post-NAC samples and found marked subtype shift (Table). We identified two robust clusters of samples according to immune expression with a 3-fold change of immune expression between them (FDR = 0.0008). We found that 4 pts switched from the low to the high cluster, while 2 switched from the high to the low cluster after NAC (Table). Conclusions: MIBC molecular subtype membership is dynamic and is influenced by NAC. NAC can induce both enhanced and suppressed immune activity. These findings have implications on future studies exploring the predictive value of RNA expression patterns for bladder cancer therapies as well as post-NAC immunotherapy. [Table: see text]

Pre-operative chemotherapy (ctx) in plasmacytoid urothelial carcinoma (PUC)

522

Background: PUC is characterized by E-cadherin loss, diffuse growth pattern and aggressive natural history. Management of this entity is controversial. This retrospective study aims to evaluate the impact of PUC histology on clinical outcomes with ctx compared to UC-NOS. Methods: Consecutive cases of nonmetastatic PUC were identified as either (1) localized disease (LD: cT2-3 cN0) or (2) locally-advanced (LA: fixed bladder or radiographic nodal disease). All cases were reviewed by a GU pathologist to confirm PUC histology per WHO classification (2016). A separate cohort of neoadjuvant(NAC)-treated UC-NOS (Tully et al, ASCO GU 2014) served as comparator for clinical outcomes. Kaplan-Meier estimates and logrank test were used for analysis of recurrence free (RFS) and overall survival (OS) defined from date of cystectomy (RC). Results: Between 2000 and 2017, eighty one PUC were identified, with median age of 65 years (range: 22 - 84) and 65% male. Thirty patients (pts) had up-front RC; 51 pts had ctx. In the former group, all pts had LD but upstaging was seen on post-op pathology: 63% pT3, 17% pT4 and 37% pN+. Among ctx pts, 33/51(65%) were LD and had NAC: 70% had ctx doublet and 24% triplet; 82% had 4 cycles and 18% had up to 6 cycles. Response ( < pT2 pN0) was seen in 7/33(22%), four (12%) of which had no residual disease (pCR). Six RC were aborted after NAC for pT4b disease. NAC response was not associated superior RFS (NR vs. 17.3 months; HR 0.52 95% CI 0.18 – 1.47, p = .218) or OS (41.3 vs. 25.5 months; HR 0.65 95% CI 0.23 – 1.87, p = .428). Compared to UC-NOS, PUC responders had significantly inferior outcomes (table). In LA cohort, majority had triplet chemotherapy (72%) and up to 6 cycles (89%). Response was seen in 4/18(22%) pts, with two pCR (11%). Five RC were aborted for pT4b disease. Median RFS and OS were 5.8 and 10.5 months, respectively, with 19% alive at 2-years. Most common sites of recurrence/progression for PUC were peritoneal (42%) and locoregional invasion (26%). Conclusions: Outcomes for PUC are poor with conventional NAC-RC approach. [Table: see text]

Mismatch repair (MMR) detection in urothelial carcinoma (UC) and correlation with immune checkpoint blockade (ICB) response

4511

Background: High mutation burden correlates with response to ICB in UC. Loss of function alterations or epigenetic silencing of MMR genes results in MMR deficient (MMR-D) UC, leading to a microsatellite instability (MSI) mutation signature. We used a CLIA-certified pipeline (MSISensor) to interrogate Next Generation sequencing (NGS) data from UC tumors to identify MMR-D patients (pts). We correlated MMR-D with mutation load and response to ICB. Methods: 447 tumors from 424 UC pts underwent prospective NGS using the MSK-IMPACT exon capture assay and genomic interrogation of microsatellite (MS) sites using MSIsensor, which assesses the number/length of MS within the targeted regions of tumor-normal sample pairs. Loci are considered unstable (somatic) if k-mer distributions are significantly different between tumor and matched normal using a standard multiple testing correction of χ2 p-values. The fraction of unstable sites is reported as an MSIsensor score. MSI high tumors have scores >10 while <3 are denoted MS stable. Scores from 3-10 were categorized as MS intermediate. Results: Thirteen pts (3%) had an MSI score >10 and a median mutation count of 52 (36.5-73.5) vs 8 (5-13) in 410 non-MMR-D pts (p<0.01). Ten pts (71%) had upper tract UC. Of 9 pts with germline sequencing performed, 8 (89%) had heritable loss of function mutations in MMR proteins (Lynch syndrome, LS). One pt had a somatic MSH2 mutation. Fifteen pts had MS scores from 3-10: 3 had LS, one a BRCA1 germline alteration, and 9 did not have germline testing available. Two pts with MSI scores <3 had extremely high mutation loads (213 and 414) and both had POLE mutations. Five pts received ICB therapy for metastatic and all achieved near-complete or complete responses. No MMR-D pt has died at 27 months follow-up vs 125 non-MMR-D pts (p=0.014). Conclusions: The MSI Sensor assay can discriminate MSI high from MMR proficient UC. While rare, MMR-D UC is characterized by a high mutation load, strong association with Lynch syndrome, and durable responses to ICB, similar to data in colon cancer. An MMR-D signature should trigger genetic testing for Lynch syndrome. ICB should be considered early in the treatment course of patients with MMR-D metastatic UC.

Nomogram to assess survival benefit of new over historical agents as salvage therapy for metastatic urothelial carcinoma (mUC) in non-randomized trials

e16012

Background: Surrogate endpoints of benefit in mUC phase 2 salvage therapy trials are necessary to identify promising drugs, particularly for checkpoint inhibitors where response and progression-free survival are inadequate. We developed a nomogram using prognostic variables from phase 2 trials of historical agents to estimate 12 month survival to which observed survival in phase 2 trials could be compared. Methods: Data were obtained from phase 2 trials of salvage therapy for mUC for survival and 5 prognostic factors: hemoglobin, performance status, liver metastasis, treatment-free interval and albumin. Patients (pts) were randomly allotted to discovery:validation (DIS:VAL) datasets in a 2:1 ratio. A nomogram was developed for estimating 12-month survival. Calibration plots were constructed in the VAL dataset by plotting estimated vs. observed 12-mo survival and data bootstrapped to assess performance. The nomogram was applied to external nonrandomized salvage therapy data: 1) retrospective pemetrexed data or 2) trials of atezolizumab: PCD4989g and IMvigor210. Results: Data were available from 340 pts receiving sunitinib (n = 77), everolimus (n = 45), docetaxel + vandetanib or placebo (n = 109), pazopanib (n = 42), paclitaxel (n = 36) and docetaxel (n = 31). Calibration and prognostic ability of the model was acceptable (c-index = 0.634, 95% CI = 0.596-0.652). Observed 12-month survival for pts on pemetrexed (n = 127, 23.5% [95% CI: 16.2%-31.7%]) were similar to nomogram-predicted survival (19% [95% CI: 16.5-21.5], P> 0.05), while observed result with atezolizumab (n = 403, 39.0% [95% CI: 34.1-43.9]) exceeded predicted result (24.6% [95% CI: 23.4-25.8], P< 0.001). Conclusions: Atezolizumab was associated with a significantly longer 12-mo survival compared to nomogram-predicted survival while pemetrexed was not. This nomogram incorporates baseline prognostic factors to provide expected 12-mo survival of phase 2 patient cohorts with which to compare observed survival, providing a useful tool to quantify benefit in phase II studies while controlling the impact of clinical variables.

DNA damage repair and response (DDR) gene alterations (alt) and response to PD1/PDL1 blockade in platinum-treated metastatic urothelial carcinoma (mUC)

4509

Background: Somatic DDR alts are associated with increased mutation load (ML) and improved clinical outcomes for platinum-treated mUC (Teo et al, CCR 2017). We examined the relationship between DDR alts and response to PD1/PDL1 blockade. Methods: mUC pts enrolled to phase 2 trials of atezolizumab or nivolumab who had targeted exon sequencing of 410 genes (MSK-IMPACT) were identified. Pts were dichotomized based on presence of alts in a panel of 34 DDR genes. Analyses were performed based on: (1) any DDR alts and (2) deleterious DDR alts (frameshift, splice site, nonsense or Hotspot point mutations). Study endpoint was overall response (OR) per RECIST. ML was defined as total number of nonsynonymous mutations by MSK-IMPACT. Fisher exact, Wilcoxon rank sum, and stratified logistic regression were used. Results: Fifty two pts were identified (atezo: n=18, nivo: n=34). Median age was 67 years (range: 32 – 84) and majority (44) was male. Median platinum-free interval was 10.2 months (range: 0.3 – 150.4). DDR and deleterious DDR were seen in 25 (48.1%) and 14 (26.9%) pts (including 2 MSI and 1 POLE). OR rate was 46.2%. Responses were associated with DDR alts but not with age, gender, treatment, platinum-free interval or ML (table). In univariate logistic regression model, DDR status was associated with OR (p<.001) while a trend was observed with ML as a continuous variable (p=.051). While DDR alts were associated with higher ML (all: p=.001, deleterious: p=.004), the effect of DDR alts on OR remained significant regardless of ML (>median: p=.027; ≤median: p=.023), indicating that the effect of DDR was independent of ML. Conclusions: DDR alts appeared to be associated with OR to PD1/PDL1 blockade and should be integrated into future validation efforts along with other potential predictors of response. [Table: see text]

Nomogram to assess benefit of new over historical agents as salvage therapy for metastatic urothelial carcinoma (mUC) in non-randomized trials: Effect of atezolizumab on 12-month survival

346

Background: Early surrogate endpoints of benefit in mUC phase 2 salvage therapy trials are necessary to identify promising drugs, particularly for checkpoint inhibitors where response and progression-free survival are inadequate. We developed a nomogram using prognostic variables from phase 2 trials of historical agents to estimate 12 month survival to which observed survival in single arm trials could be compared. Methods: Data were obtained from phase II trials of salvage therapy for mUC for survival and 5 prognostic factors: hemoglobin, performance status, liver metastasis, treatment-free interval and albumin. Patients (pts) were randomly allotted to discovery:validation (DIS:VAL) datasets in a 2:1 ratio. A nomogram was developed for estimating 12-month survival. Calibration plots were constructed in the VAL dataset by plotting estimated vs. observed 12-mo survival and data bootstrapped to assess performance. The nomogram was applied to external nonrandomized salvage therapy data: 1) retrospective pemetrexed data or 2) trials of atezolizumab: PCD4989g and IMvigor210. Results: Data were available from 340 pts receiving sunitinib (n = 77), everolimus (n = 45), docetaxel + vandetanib or placebo (n = 109), pazopanib (n = 42), paclitaxel (n = 36) and docetaxel (n = 31). Calibration and prognostic ability of the model was acceptable (c-index = 0.634, 95% CI = 0.596-0.652). Observed 12-month survival for pts on pemetrexed (n = 127, 23.5% [95% CI: 16.2%-31.7%]) were similar to nomogram-predicted survival (19% [95% CI: 16.5-21.5], P> 0.05), while observed result with atezolizumab (n = 403, 39.0% [95% CI: 34.1-43.9]) exceeded predicted result (24.6% [95% CI: 23.4-25.8], P< 0.001). Conclusions: Atezolizumab was associated with a significantly longer 12-mo survival compared to nomogram-predicted survival while pemetrexed was not. This nomogram incorporates baseline prognostic factors to provide expected 12-mo survival of phase 2 patient cohorts with which to compare observed survival, thereby providing a useful tool to quantify benefit in phase II studies while controlling for the impact of clinical variables.

Evaluation of monocytic myeloid-derived suppressor cell (M-MDSC) frequency in patients with metastatic urothelial carcinoma (mUC)

356

Background: M-MDSCs promote tumor progression through complex mechanisms, including immunosuppression and the production of mediators of angiogenesis and invasion. M-MDSCs are associated with poor outcomes in a number of malignancies. We conducted an exploratory analysis enumerating M-MDSCs (Lin-CD14+/HLA-DRlow/-) in the blood of pts with mUC and assessed for assay variability and correlation with clinical outcomes. Methods: Whole blood was collected at a single time point for each pt and stabilized in Cyto-Chex tubes. M-MDSC% was calculated by flow cytometric analysis of HLA-DR expression on CD14+ monocytes using an MSKCC developed computational algorithm-based approach (Kitano et al. 2014). Individual samples were run in quadruplicate at MSKCC. The mean MDSC% was used in subsequent analyses and the replicate standard deviation (SD) was considered a reflection of intra-assay variability. Clinical variables were collected and pts followed for OS, which was calculated from time of sample collection. Results: 21 pts with mUC who progressed after prior chemotherapy were included. At the time of collection, pts were on clinical trials with immune checkpoint blockade (n=13) or targeted therapy (n=1), receiving salvage chemotherapy (n=2), or awaiting treatment on clinical trials with immune checkpoint blockade (n=4) or targeted therapy (n=1). The median follow up from the time of collection in surviving patients (n=15) was 11.1 months (range: 10.5-11.5). Median OS was not reached. Mean (SD) M-MDSC% was 29.2 (4.92). The range of replicate SD was 0.13-1.05. M-MDSC% was not higher in pts with visceral mets (p=0.109). Pts with above median M-MDSC% had worse OS (p=0.01; 6 patients died during follow up, all with above median M-MDSC%). Conclusions: In a heterogeneous cohort of pts with mUC, the enumeration of M-MDSCs in stabilized whole blood was feasible and demonstrated marked inter-patient but not intra-assay variability. Pts with higher M-MDSC% values had worse OS. Additional characterization of M-MDSCs in larger cohorts and in pts receiving immunotherapy is ongoing and may have important prognostic and therapeutic implications in mUC.

Multicenter prospective phase II trial of neoadjuvant (neo) dose dense gemcitabine and cisplatin (DD-GC) in patients (pts) with muscle-invasive bladder cancer (MIBC)

436

Background: Cisplatin-based chemotherapy before radical cystectomy (RC) improves survival in pts with MIBC. DD-GC therapy is active in the metastatic setting [6 cycles (cy), 18 months median survival; Bamias et al, 2012)] and as neo therapy (3 cy, 44% ≤ pT1 rate; Plimack et al, 2014), but the optimal dose and number of cy of neo therapy has not been defined. We prospectively evaluated the activity and safety of 6 cy of neo DD-GC over 12 weeks in MIBC. Methods: Pts with T2-4aN0 disease received six 14-day cy of DD-GC as follows: G 2500 mg/m2 day 1, C 35 mg/m2 days 1 and 2, pegfilgrastim day 3. RC with bilateral pelvic lymph node dissection was planned within 8 weeks of DD-GC completion, regardless of clinical response. The primary endpoint was pathologic response ( ≤ pT1) rate ≥ 55% (exact Binomial one-sided test). Pts not undergoing RC were deemed non-responders regardless of clinical stage after DD-GC. Pts receiving < 3 cy were inevaluable and replaced. All pts were evaluable for toxicity. Results: 49 pts (40 male) were enrolled. Median age was 64 (range: 37-78). Clinical stage was T2N0 (32 pts), T3N0 (12 pts), and T4aN0 (5 pts). Toxicities resulting in cy delay and/or dose modifications included thrombocytopenia (9 pts), renal insufficiency (5 pts), vascular access complication (2 pts), ototoxicity (1 pt), significant urinary symptoms (1 pt), and transient ischemic attack (1 pt). Three pts are inevaluable for the primary endpoint ( < 3 cy). As of 9/7/15, 2 pts are pending RC. Of the 44 pts evaluable for response to date, 31 completed 6 cy of DD-GC, 6 pts completed 5, 3 pts completed 4, and 4 pts completed 3 (median: 6 cy). The median time to RC was 46 days. Four of 44 pts did not undergo RC (consent withdrawal, pt refusal, disease progression prior to RC, death from other causes). Trial accrual has closed with completion of clinical and pathologic data expected by 11/1/15. Of 40 pts with RC pathology available to date, 24 (60%) were ≤ pT1 and 7 (18%) were pT0. Conclusions: Six cy of DD-GC is an active well-tolerated neo chemotherapy regimen in pts with MIBC. The pathologic response rate is encouraging. Thrombocytopenia was the most common toxicity resulting in cy delays/dose modifications. Clinical trial information: NCT01589094.

Phase I trial of gemcitabine and split-dose cisplatin plus everolimus (RAD001) in patients with advanced urothelial cancer

322

Background: Gemcitabine and split-dose cisplatin (GC) is standard first-line therapy for patients with advanced urothelial cancer (UC). Everolimus is an inhibitor of the PI3K/AKT/mTOR pathway, dysregulated in ~35% of UCs. The drug has been shown to have single-agent activity in phase II trials of advanced UC. The safety of combining everolimus with GC in the first-line setting for UC is unknown. Methods: Previously untreated cisplatin-eligible patients with advanced UC were enrolled. Patients received gemcitabine 800 mg/m2 and cisplatin 35mg/m2 on days 1 and 8 with everolimus at dose levels (DL1: 5 mg QOD, DL2: 5 mg daily or DL3: 10 mg daily) for six 21-day cycles. Patients with at least SD continued maintenance everolimus until progression. Restaging evaluations were performed every 2 cycles. The primary objective was to establish the dose-limiting toxicity (DLT) and maximum tolerated dose (MTD) of the three-drug combination. Results: 12 patients were enrolled, 7 with bladder and 5 with upper tract primaries. 4/12 patients completed at least 6 cycles. 0/3 patients at DL1 had DLTs. 3/3 patients at DL2 had DLTs (pancytopenia, hypersensitivity reaction to everolimus and anemia). Following de-escalation to DL1, 2/6 patients in a new DL1 cohort had DLTs (neutropenia and diarrhea, 1/6 patients inevaluable). Grade 3/4 events included anemia (67%), neutropenia (42%), lymphopenia (42%), thrombocytopenia (25%), urinary tract infection (25%), hypomagnesemia (17%), and hypophosphatemia (17%). Tumor responses included: 4 PR (33%), 5 SD (42%), 1 PD (8%), and 2 inevaluable (17%). 2 patients with PR underwent consolidative surgery but eventually progressed. Responses by MSKCC Risk Scores of 0, 1, and 2 were seen in 3/5 (60%), 1/6 (17%), and 0/1 patients, respectively. Median PFS was 3.9 months (95% CI, 3.7-no reached) and median OS was 10.8 months (95% CI, 6.9-not reached). Conclusions: MTD was reached at DL1 for combination gemcitabine, split-dose cisplatin and everolimus, with 2/8 evaluable patients exhibiting DLTs at this dose level. Clinical trial information: NCT01182168.

Improved prognostic classification of patients receiving salvage systemic therapy for advanced urothelial carcinoma

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Background: Previously identified prognostic factors in patients (pts) receiving salvage systemic therapy for advanced urothelial carcinoma (UC) include performance status (PS), liver metastasis (LM), hemoglobin (Hb) and time from prior chemotherapy (TFPC). Given the prognostic impact of peripheral blood neutrophils (N), lymphocytes (L), thrombocytes (T) and albumin (Alb) in other malignancies, we investigated their impact in the salvage setting of advanced UC. Methods: Phase II trials of salvage systemic therapy were utilized. Data on N, L, T and Alb were required in addition to TFPC, Hb, PS and LM status. N, L, T and Alb were categorized as normal, <lower limit of normal (LLN) and >upper limit of normal (ULN). Cox proportional hazards regression was used to evaluate their association with overall survival (OS). An optimal regression model was constructed using forward stepwise selection and risk groups defined using number of identified adverse risk factors. Trial was a stratification factor. Results: Data was obtained from 10 trials accruing 708 pts. Of these, 682 pts had available TFPC, Hb, PS and LM status, while 631, 554, 649 and 491 had N, L, T and Alb available. Median OS was 6.8 (95% CI: 6.0-7.0) months. Neutrophilia (N>ULN), thrombocytosis (T>ULN) and hypoalbuminemia (Alb <LLN) were significant poor prognostic factors for OS on univariate analyses. After adjustment for TFPC <3 months, Hb <10 g/dl, PS >0 and LM status, only thrombocytosis and hypoalbuminemia remained significant (Table). Risk groups were constructed. Median OS was 8.8, 6.3, 5.0 and 3.8 months for n=290, 220, 123 and 49 patients with 0-1, 2, 3 and ≥4 factors. This 6-factor prognostic model was internally validated with an improvement in the c-index from 0.564 to 0.590. Conclusions: The addition of hypoalbuminemia and thrombocytosis to TFPC, Hb, PS and LM status enhanced the prognostic risk groupings in pts receiving salvage systemic therapy for advanced UC. [Table: see text]

Split-dose cisplatin as an alternative to every-3-week dosing when using cisplatin/gemcitabine to treat advanced urothelial cancer

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Background: Cisplatin-based chemotherapy is the standard of care first-line therapy for locally advanced or metastatic urothelial cancer (mUC) with reported response rates (ORR) of 50%, median progression free survival (mPFS) 7 months and median overall survival (mOS) 14 months in phase III trials using cisplatin 70 mg/m2 every 3 weeks (q3wk). Many patients cannot receive cisplatin due to impaired performance status, renal dysfunction, or other co-morbidities. Carboplatin is an alternative but is associated with lower response rates and shorter survival. Administering cisplatin 35 mg/m2 day 1+8 (i.e., split dose) every 3 weeks may be associated with lower toxicity and allow more patients receive the drug. In this retrospective analysis we examined the safety and efficacy of cisplatin/gemcitabine using split dose cisplatin. Methods: Patients who received split dose cisplatin/gemcitabine between 2007-2013 were identified. We recorded baseline demographics, clinical characteristics, and number of cycles administered. Responses were determined retrospectively using RECIST v1.1; OS and PFS were assessed using the Kaplan-Meier method. Results: 50 patients were identified and baseline characteristics are outlined in Table 1. The median number of cycles administered was 4 (range 1-7). 25 patients (50%) discontinued therapy due to completion of planned course, 14 (28%) due to progressive disease and 11 (22%) due to toxicity. ORR was 54%, mPFS was 5.4 months (95% CI: 4.2 – 8.8) and mOS was 13.3 months (95% CI: 9.6 – 21.9). Conclusions: In this analysis, split-dose cisplatin was administered safely in patients who were deemed ineligible for the q3wk regimen and efficacy did not appear to be compromised. The split-dose regimen may allow more patients tolerate cisplatin, the most active FDA-approved drug in this disease. [Table: see text]

Gemcitabine-cisplatin (GC) plus radical cystectomy-pelvic lymph node dissection (RC-PLND) for patients (pts) with muscle-invasive bladder cancer (MIBC): Assessing impacts of neoadjuvant chemotherapy (NAC) and the PLND

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Background: NAC and RC-PLND improves survival in MIBC and GC is a standard NAC option. However, little is known about GC efficacy endpoints and the individual contribution of NAC and surgery. Methods: Pts with clinical T2-T4aN0M0 MIBC treated from 1/2000 to 10/2012 with a planned 4 cycles of GC plus RC-PLND within 90 days (D) of NAC were evaluated retrospectively for the number (#) of cycles, dose delivered, D from end of NAC to RC-PLND, margin status, LN status and # of LN identified. Post-NAC pathologic endpoints included complete response (pT0), residual Non-MIBC disease (pTa/Tis/T1;N0) and ≥MIBC disease (≥pT2N0). Associations with overall survival (OS) and disease-free survival were analyzed using Cox regression; non-linear associations with # of resected LN used linear and quadratic terms. Results: 154 pts met inclusion criteria. 5-year (yr) OS was 61% (95% CI 53-71%). Post-NAC pT0 was achieved in 21% (32/154) and Non-MIBC in 25% (39/154 - pTa (2), pTis (25), pT1 (12)). Post-NAC pT0 and Non-MIBC had similar 5-yr OS (85% and 89%, respectively) and combined (<pT2) pts differed significantly from pts with ≥pT2, (87% (95% CI 78, 98%) and 38% (95% CI 27, 53%), respectively; p<0.001). Median D from NAC to RC-PLND was 34 and median # of resected LN was 19. On univariate analysis, # of cycles (4 vs <4), GC dose intensity and total dose, clinical stage (cT2 vs cT3/cT4), # of resected LN, positive (+) LN and + margins were significant for OS. In multivariate analysis, post-NAC pathology ≥pT2 (HR 6.7; 95% CI 2.6-17.4; p<0.001), + LN (HR 3.21; 95% CI 1.6-6.4; p=0.001) and + margins (HR 3.2; 95% CI 1.4-7.5; p=0.007) were significant for increased risk of death. Using a model with these 3 predictors to estimate the benefit of PLND, the hazard ratio decreased with each LN resected until 25 and then plateaued beyond 25 (p=0.016). Conclusions: NAC with GC has excellent drug delivery, permits rapid RC-PLND and achieves meaningful pathologic responses. Survival is similar with <pT2N0 and pT0N0 post NAC pathology. Pts with post NAC ≥pT2, + margins, and + LN do poorly. Increasing LN yield on PLND contributes to OS.

Impact of number of lines of prior chemotherapy in patients (pts) with advanced urothelial carcinoma (UC) receiving salvage therapy

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Background: The prognostic impact of number of lines of prior chemotherapy and prior perioperative chemotherapy on survival results in salvage trials for advanced UC is unknown. Methods: We pooled 10 prospective phase II trials of salvage therapy for advanced UC with data on the number of prior lines of therapy in addition to known prognostic factors: TFPC (time from prior chemotherapy), Hb (hemoglobin), PS (performance status), and LM (liver metastasis) status. Cox proportional hazards regression was used to evaluate the association of number of prior lines with overall survival (OS) and progression-free survival (PFS). Trial was included as a stratification factor. Sub-analysis examined the impact of prior perioperative chemotherapy. Results: Of 731 pts, data for all factors was available for 711. The overall median PFS and OS were 2.7 and 6.8 months, respectively. Trials evaluated vinflunine (N=151), docetaxel +/- vandetanib (N=147), paclitaxel-gemcitabine (N=83), sunitinib (N=77), nab-paclitaxel (N=48), volasertib (N=46), everolimus (N=45), pazopanib (N=43), cetuximab +/-paclitaxel (N=39) and paclitaxel-cyclophosphamide (N=32). The number of prior lines of therapy were 1 in 559 (78.6%), 2 in 111 (15.6%), 3 in 29 (4.1%), 4 in 10 (1.4%) and 5 in 2 (0.3%) pts. Prior perioperative chemotherapy was given to 277 (39.1%) and chemotherapy for metastatic disease to 454 (64.1%) pts. While TFPC, Hb, PS and LM were significantly associated with OS and PFS on multivariate analyses, the number of prior lines was not associated with OS (HR 0.99 [95% CI: 0.86-1.14]) or PFS (0.92 [0.80-1.05]). Prior peri-operative chemotherapy was a favorable factor for both OS and PFS on univariable but not multivariable analysis. Conclusions: The number of prior lines of therapy and prior perioperative chemotherapy were not independently prognostic for OS or PFS in UC pts receiving salvage therapy, although the data are limited by few pts with >2 prior regimens. We infer that interpretation of OS and PFS results in salvage therapy trials will not be affected by inclusion of pts with ≥ 2 prior regimens including perioperative and/or metastatic disease treatment. These data need external validation.

Impact of prior platinum agent and site of primary in patients with advanced urothelial carcinoma (UC) receiving salvage therapy

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Background: The prognostic impact of prior platinum agent (cisplatin vs. carboplatin) and site of primary (bladder vs. other) in the context of salvage therapy for advanced UC is unknown. Methods: We pooled 10 prospective phase II trials of ≥ second-line therapy for advanced UC with data recorded for prior platinum agent and site of primary in addition to major prognostic factors: TFPC (time from prior chemotherapy), Hb (hemoglobin), PS (performance status), and LM (liver metastasis) status. Cox proportional hazards regression was used to evaluate the association of prior platinum agent and site of primary with overall survival (OS) and progression-free survival (PFS). Trial was included as a stratification factor throughout. Kaplan-Meier method was used to estimate PFS and OS. Results: Of 731 patients overall, 559 had received one prior chemotherapy regimen, 663 were evaluable for prior platinum regimen and 512 for site of primary. The overall median PFS and OS were 2.7 and 6.8 months, respectively. The trials evaluated vinflunine (N=151), docetaxel +/- vandetanib (N=148), paclitaxel-gemcitabine (N=98), sunitinib (N=77), volasertib (N=50), nab-paclitaxel (N=48), everolimus (N=45), pazopanib (N=43), cetuximab +/-paclitaxel (N=39) and paclitaxel-cyclophosphamide (N=32). Prior platinum was cisplatin in 501 (75.6%) and carboplatin in the rest. Prior carboplatin was associated with worse OS on univariate analysis (HR 1.23 [1.00-1.52], P=0.048) but not significantly associated with either OS or PFS on multivariate analysis. Bladder was the site of primary in 388 (75.8%). The site of primary was not significantly associated with PFS and OS in either univariate or multivariate analyses. Conclusions: Neither prior platinum agent (cisplatin vs. carboplatin) nor site of primary (bladder vs. other) were independently associated with OS or PFS in patients receiving salvage therapy for advanced UC. Trials of salvage therapy may continue to utilize the previously recognized prognostic factors, and could allow patients with all sites of primary disease and regardless of the prior platinum agent. These data need external validation.

The high incidence of vascular thromboembolic events (VTE) in advanced urothelial cancer (UC) patients (pts) treated with carboplatin (Cb): Analysis of treatment with gemcitabine (G)/cb (GCb), gcb/bevacizumab (GCbBev), or gemcitabine/cisplatin (GCis)

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Background: VTE occur in ~13% of pts receiving Cis-based therapy for UC. Cb-based therapy is considered less thrombogenic but no definitive data exist to support this conclusion. While Bev added to chemotherapy (Ch) increases VTE in other tumors, VTE impact when added to UC Ch is unknown. This study evaluated the incidence of and etiologic factors for VTE in UC pts treated with GCb, GCbBev and GCis. Methods: UC pts treated from 6/2006 to 6/2010 on a GCbBev protocol were analyzed prospectively. Planned therapy was 6 cycles of GCbBev then Bev alone; pts who had ≥ 3 cycles were included. Similar UC pts treated with GCb or GCis during the same time were retrospectively evaluated. Type of VTE and potential contributing clinical factors were collected. VTE was defined as pulmonary embolism, vascular thrombosis, myocardial infarction or cerebral vascular accident. Associations with Ch regimen were tested using Fisher’s exact test or linear regression. Factors associated with VTE were analyzed using conditional logistic regression stratified by Ch regimen. Results: 198 pts were analyzed. VTE occurred in 13/51 (26%) GCbBev pts, 22/92 (24%) GCb pts, and 8/55 (15%) GCis pts. Age (≤65 vs >65; p<0.001), having had a prior cystectomy (p<0.001), mass near pelvic vessels (p=0.027), Khorana risk group (p=0.025) and anti-platelet therapy (p=0.036) were significantly associated with the Ch regimen reflecting cohort-specific differences. Type of Ch was not associated with any VTE (p=0.3) or type of VTE (arterial vs venous) (p=0.11). Having had a prior cystectomy was associated with increased risk of VTE (OR 2.2, 95% CI 1.0-5.0, p=0.047). Conclusions: This is the largest series reporting VTE in Cb-treated UC pts; the VTE rate of 24% (95% CI 17, 32%) is higher than expected. Bev does not appear to increase this risk. VTE in Cis-treated pts (15%) was similar to prior reports. The finding that pts with advanced UC are at high risk of VTE regardless of the specific platinum agent warrants further study of Cb therapy-related risk and analysis for contributing factors including prior pelvic surgery.

Germline single nucleotide polymorphisms associated with response of urothelial carcinoma to platinum-based therapy: the role of the host

BACKGROUND

Variations in urothelial carcinoma (UC) response to platinum chemotherapy are common and frequently attributed to genetic and epigenetic variations of somatic DNA. We hypothesized that variations in germline DNA may contribute to UC chemosensitivity.

PATIENTS AND METHODS

DNA from 210 UC patients treated with platinum-based chemotherapy was genotyped for 80 single nucleotide polymorphisms (SNPs). Logistic regression was used to examine the association between SNPs and response, and a multivariable predictive model was created. Significant SNPs were combined to form a SNP score predicting response. Eleven UC cell lines were genotyped as validation.

RESULTS

Six SNPs were significantly associated with 101 complete or partial responses (48%). Four SNPs retained independence association and were incorporated into a response prediction model. Each additional risk allele was associated with a nearly 50% decrease in odds of response [odds ratio (OR) = 0.51, 95% confidence interval 0.39-0.65, P = 1.05 × 10(-7)). The bootstrap-adjusted area under the curves of this model was greater than clinical prognostic factors alone (0.78 versus 0.64). The SNP score showed a positive trend with chemosensitivity in cell lines (P = 0.115).

CONCLUSIONS

Genetic variants associated with response of UC to platinum-based therapy were identified in germline DNA. A model using these genetic variants may predict response to chemotherapy better than clinical factors alone.

Single nucleotide polymorphisms as markers of bacillus Calmette-Guérin intravesical therapy response in non-muscle invasive bladder cancer

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Background: A marker of response to Bacillus Calmette-Guérin (BCG) intravesical therapy in high-risk non-muscle invasive bladder cancer (NMIBC) could help avoid unsuccessful BCG treatment and potentially enhance care. This study examines germline single nucleotide polymorphisms (SNPs) as markers of BCG-refractory NMIBC. Methods: Saliva or blood was prospectively collected from patients treated with BCG for NMIBC between 1991 and 2010, treated either at MSKCC or referring centers prior to MSKCC registration. BCG-refractory disease was defined as the presence of pathologically documented tumor in the bladder six months after BCG administration. SNPs were selected based on either reported associations with BCG response or putative mechanisms of BCG activity. Eighty candidate SNPs were genotyped (using the Sequenom Mass ARRAY iPLEX platform) in a discovery set (n=158) and those significantly associated were analyzed in a validation set (n=168). Univariate logistic regression was used to test the association between refractory disease, selected clinical variables, and SNPs. Because center of treatment was found to be a confounding variable (p=0.02), primary analysis was limited to cases treated at a single center (MSKCC), consisting of 276 patients (108 from discovery set and 168 from validation set). Results: Median age of diagnosis of the 276 cases was 65.7 years, 94% diagnosed with high-grade superficial bladder cancer, 35% stage Ta, 30% stage T1, and 35% stage Tis. At six month follow-up, 37 (13.4%) had BCG–refractory disease. Nine SNPs showed significant associations with outcome in the discovery cohort (two SNPs failed genotyping). In primary analysis, One SNP, rs11615, an intronic variant within the ERCC1 gene, was associated with BCG-refractory disease. Patients with CC genotype were 3.6 times more likely to be refractory to BCG compared to TT genotype (OR for each C allele was 1.8: 95% CI 1.1-3; p=0.01). No other factors were found to be predictive. Conclusions: A single nucleotide polymorphism of ERCC1 may be associated with BCG-refractory disease. Validation in independent datasets is needed.

Phase II trial of neoadjuvant gemcitabine (G) and cisplatin (C) with sunitinib in patients (pts) with muscle-invasive bladder cancer (MIBC)

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Background: Response to neoadjuvant chemotherapy (NC) prior to radical cystectomy (RC) predicts improved overall survival (OS) in MIBC. Associations with enhanced survival include complete pathologic response (pT0; Grossman, NEJM 2003) and eradication of the muscle-invasive component (<pT2; Splinter, J Urol 1992). Sunitinib (S) is active in pretreated pts with advanced disease. We tested if S added to GC was safe, improved the rate of pT0, and improved the rate of <pT2. Methods: Cisplatin-eligible pts with cT2-4aN0 bladder cancer received G 1000 mg/m2 and C 35 mg/m2 on day (D) 1 and D8 with S 25 mg orally daily D1-14 of a 21D cycle for 4 cycles. RC plus pelvic lymph node dissection was required to assess response of pT0 or <pT2. A Simon’s Minimax 2-stage design was used to test a null (H0) pT0 rate ≤ 20% against alternative (H1) pT0 rate ≥ 40% with Type I and II error rates of 0.05 and 0.10 respectively. Enrollment to the 2nd stage of 45 patients was planned if ≥ 6 of the initial 24 evaluable pts achieved pT0. Primary endpoint was pT0N0 and secondary endpoints were: response defined as <pT2N0; safety; time to progression (TTP), and OS. Results: 18 pts (15M, 3F), median age 63 (54-76) were enrolled from 6/09 and 10/11 after which financial support was withdrawn. 3 pts were inevaluable for response endpoints due to: 1.) withdrawal of consent, 2.) declining any surgery, 3.) partial cystectomy instead of RC. All 18 were evaluable for safety, TTP and OS. 1 of 15 pts had pT0N0 (6.6%; 95% CI 0.34 – 29.8%) and 5 had <pT2N0 (33%; 95% CI 15-58%). 4 of 5 pts with status <pT2N0 were pTisN0. Median TTP was 10 months (95% CI 3.5-NR). 3 pts were deceased at time of analysis; median OS not reached. Neutropenia due to the 3 drug combination required routine GCSF support on day 8 of each cycle. Grade 3/4 toxicities were anemia (11 pts), neutropenia (6), thromboembolic events (2), febrile neutropenia (2) and infection (2). Conclusions: Despite incomplete accrual, the pT0 rate was low suggesting that S does not add to GC. Residual non-invasive disease (<pT2) was common, including a large proportion of pts with pTisN0. Given these findings, response criteria for future NC studies should consider either <pT2 or < pTis as the primary endpoint.

Association of single-nucleotide polymorphisms in BCL2L1 and TACC3 with response to bacillus Calmette-Guérin intravesical therapy in non-muscle-invasive bladder cancer

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Background: Bacillus Calmette-Guérin intravesical therapy (BCG) has an important role in the management of high risk non-muscle-invasive bladder cancer (NMIBC). This study examines the association between germline single nucleotide polymorphisms (SNPs) and response to BCG therapy.

Methods: Saliva or blood was collected from pts with NMIBC treated at a single center and diagnosed between 1984 and 2010. SNPs were selected based on reported associations with bladder cancer and BCG response, and genotyped using the Sequenom MassARRAY iPLEX system. No response to BCG was defined as the presence at 6 months of pathologically documented tumor in the bladder. Univariate logistic regression was used to test the association between the outcome of interest (no response to BCG at 6 months) and clinical variables (stage, grade and multifocality), or individual SNPs.

Results: The cohort consisted of 158 pts with a median age of 65 years who received intravesical BCG for NMIBC (35.2% stage T1, 32.7% stage Ta and 31.4% stage Tis) with 93% having high-grade disease. At 6 months follow up, 22 (13.9%) patients showed no response to BCG. We successfully genotyped 80 of the 88 selected SNPs. Of these, 2 SNPs were associated with lack of response to BCG; rs798766 is an intronic SNP in TACC3 (OR for no response is 2.4 for each T allele relative to CC genotype, P=0.01), and rs1994251 an intronic SNP in BCL2L1 (OR for no response is 3.2 for each C allele relative to AA, p= 0.0008). Both SNPs remained significantly associated with lack of response after adjusting for predictive clinical variables.

Conclusions: Single nucleotide polymorphisms of BCL2L1 and TACC3 may be predictive of BCG refractory bladder cancer. Future validation studies on independent datasets are needed to determine the clinical utility of these findings.

Alterations in the PI3K/Akt signaling pathway and association with outcome in invasive high-grade urothelial cancer (UC)

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Background: Activating mutations in PIK3CA have been associated with improved outcomes in patients (pts) with breast cancer (Kalinsky, Clin Cancer Res 2009). Molecular profiling of invasive high-grade UC demonstrates that PI3K/Akt pathway alterations occur in up to 15% of cases. The prognostic value of PI3K/Akt pathway alterations in invasive UC is unknown.

Methods: Clinically annotated archival frozen surgical specimens from 95 pts (94 cystectomies, 1 nephroureterectomy) with high-grade invasive UC were genotyped for mutations in all coding exons of PIK3CA, PIK3R1, TSC1, PTEN and the AKT isoforms using high-throughput Sanger sequencing. Copy number alterations were examined using an Agilent 1M oligonucleotide array. Clinical variables including time to recurrence (TTR) and overall survival (OS) were correlated with the presence of mutations or copy number events in PIK3CA, PIK3R1, TSC1, PTEN and the AKT isoforms.

Results: Specimens from 95 pts (71 M; 24 F) with a median age of 71 years (41-88) were evaluated. 34 (36%) received neoadjuvant chemotherapy and 75 (79%) were prior smokers. 4 pts (4%) had Stage 0, 11 (12%) had Stage I, 15 (16%) had Stage II, 33 (35%) had Stage III and 32 (34%) had Stage IV disease at surgery. The median follow-up was 31.5 months. Alterations (mutations or copy number gains/losses) in PI3K/Akt signaling pathway genes were identified in 26 (27%) specimens and were associated with a trend toward longer TTR, hazard ratio 0.53 (95%CI 0.24, 1.14) (p=0.08).

Conclusions: Alterations in PI3K/Akt signaling in pts with invasive UC may be associated with an improvement in outcome similar to that observed in breast cancer. Further analysis in a large independent tumor set is ongoing.