Implications of ethnicity among patients with metastatic renal cell carcinoma (mRCC) treated with nivolumab plus ipilimumab (nivo/ipi)

613

Background: Existing literature has reported differences in clinical outcomes by ethnicity in patients receiving immune checkpoint inhibitors (Olsen et al Front Oncol 2021). We investigated real-world outcomes between Latinx and non-Latinx mRCC patients treated with first-line nivo/ipi within a safety-net healthcare system and at a tertiary care center in Southern California. Methods: We performed a retrospective analysis of mRCC patients who received nivo/ipi within the Los Angeles County Department of Health Services (DHS), a safety-net healthcare system, and the City of Hope Comprehensive Cancer Center (COH), a tertiary oncology center, between Jan. 1, 2015 and Dec. 31, 2021. Patients were identified using institutional databases and clinical data were compiled from electronic health records. Patients with pathologic diagnosis of mRCC, age > 18 years and receipt of nivo/ipi as first-line therapy were included. Progression-free survival (PFS) and overall survival (OS) were analyzed using the Kaplan-Meier method, log-rank test, and Cox proportional hazards model with adjustments for other covariates. Results: Of 94 patients, 66 (70%) were male, 90 (94%) had clear-cell histology, and 87 (93%) had IMDC intermediate/poor risk disease. Forty patients (43%) were Latinx. Fifty (53%) and 44 (47%) patients received their care at a tertiary care center and within a safety-net healthcare system, respectively. Most Latinx patients (95%) were treated at DHS, and most non-Latinx patients (89%) were treated at COH. Latinx patients were significantly older than non-Latinx patients (59.5 vs 55 years, p=0.008). IMDC risk classification, body mass index, history of nephrectomy, and number of comorbidities were similar between both groups. Pooled analysis by ethnicity demonstrated significantly shorter PFS in Latinx versus non-Latinx patients (10.1 vs 25.2 months, HR 3.61, 95% CI 1.96-6.66, p= <0.01). Adjusting for age, gender, IMDC risk classification, history of nephrectomy, and number of co-morbidities, multivariate analysis revealed a HR of 3.41 (95% CI 1.31-8.84; p=0.01). At a median follow up of 11.0 months, the median OS was not met in either arm at the time of data cutoff (NR vs. NR, HR 1.34, 95% CI 0.44-4.11). Conclusions: Compared to non-Latinx patients,Latinx patients demonstrated shorter PFS; no difference was observed in OS although these data were immature. As the majority of Latinx patients received their care at DHS, our data suggest that disparities in access to care may significantly contribute to differences in clinical outcomes of mRCC patients receiving nivo/ipi.

Impact of race and payer status on the choice of urinary diversion among patients with localized bladder carcinoma undergoing cystectomy

455

Background: Prior studies have described significant disparities in the selection of urinary diversion (UD) in patients with localized bladder cancer undergoing cystectomy. Although the choice of UD has not been shown to impact oncologic outcomes, continent urinary diversions (CUD) are associated with lower rates of in-hospital complications and mortality, but higher costs (Farber NJ et al. Bladder Cancer 2018). Male gender, White race, and higher income have been associated with proportionally higher rates of CUD than patients from other races or those without private insurance (Barocas DA et al. Cancer 2014 and Rios EM et al. Urology 2020). Utilizing the California Office of Statewide Health Planning and Development (OSHPD) database, we investigated potential barriers to CUD in patients with bladder cancer undergoing radical cystectomy. Methods: The current procedural terminology (CPT) and the international classification of diseases (ICD)-9/10 codes were used to identify patients with bladder cancer undergoing radical cystectomy from Jan 1, 2012, through Dec 31, 2018. Type of UD and demographic data such as race and payer status were collected. Univariate and multivariable analyses were conducted to determine the association between demographic variables and CUD use. Results: In total, 9,342 patients who underwent radical cystectomy were identified, of which 3,061 had UD status noted. Of these, 13.2% (404/3061) were continent and 86.2% (2,657/3061) were incontinent diversions. CUD use was significantly higher in White patients (14.1%; 320/2276) compared to Asian (12.8%; 24/187), Hispanic (9.5%; 30/316) or Black (5%; 6/119) patients (P=0.01). Use of CUD was significantly higher in patients with private insurance (23.2%; 167/721) compared to those with Medicare (10.2%; 207/2023) or indigent (MediCal/Medicaid; 8.6%; 23/269; p<0.001) coverage. On multivariable analysis adjusting for comorbidities and care setting, Black (OR: 0.30, 0.13-0.69) and Hispanic (OR: 0.57, 0.38-0.86) race were associated with a lower probability of getting a CUD, while male patients (OR 1.88, 1.31-2.71) and those receiving care at academic centers (OR 3.10, 2.38-4.05) were more likely to receive a CUD. Payer status did not show a significant difference between the two procedures. Finally, the presence of chronic kidney disease represented a risk factor for not getting a CUD (OR: 0.61, 0.43-0.85), but not the presence of diabetes and frailty. Conclusions: Black or Hispanic race and female gender were associated with lower rates of CUD when controlling for other factors. We hypothesize that the higher costs for CUD, communication barriers, especially with non-English speakers, comorbidities, and a potential lack of cultural humility could lead to an unconscious bias from the healthcare team. Further research aimed at understanding and addressing these disparities is needed.

Spectrum and implications of activating BRAF alterations in advanced prostate cancer (aPC)

220

Background: Activating genomic alterations (GA) in BRAF are rare in aPC and their impact on pathogenesis is poorly understood. However, emerging data suggest that these GA may represent clinically actionable targets (Fenor et al, Clin Transl Oncol, 2022). Using comprehensive genomic profiling (CGP) performed in a single commercial lab, we characterized the GA landscape of BRAF-activated tumors in aPC patients (pts). Methods: Tissue(N=15,864) and liquid (N=7,566) biopsies from aPC pts were profiled using FoundationOne CDx and FoundationOne Liquid CDx CGP assays, respectively. Each assay covers 324 cancer-related genes, including the full coding region of BRAF and introns 7-10, with additional sensitivity in exons 11-18 in the liquid assay. Activating GA were defined as hotspot missense mutations, in-frame indels in the kinase domain, or rearrangements (RE) that preserve the kinase domain. Tissue biopsies from non-aPC cancer types (N= 275,151) were used for comparison. Results: BRAF-activating GA were detected in 520/15,864 (3.3%) tissue biopsies: RE were the most common GA (243 samples, 1.5%), followed by K601E (101, 0.6%), and G469A (58, 0.4%). Median age of pts with BRAF-altered tumors was 69 (interquartile range 63-76), compared to 68 for BRAF wild-type (interquartile range 62-74). Rearrangement breakpoints occurred most frequently in intron 8 (37%), intron 9 (28%), intron 10 (20%), and intron 7 (13%). The most common RE were BRAF N-terminal truncations removing the auto-inhibitory domain (22%), SND1-BRAF fusions (13%), intragenic BRAF deletions of the auto-inhibitory domain (12%), and TMPRS22-BRAF fusions (5%). When studying cases with BRAF-activating GA compared to wild-type, we noted a larger proportion of CDK12 mutations (9.2% vs 5.2%, p=0.018), and a depletion of TMPRSS2-ERG fusions (11% vs 32%, p<0.0001), PTEN GA (17% vs 31%, p<0.0001), and APC GA (4.4% vs 8.9%, p = 0.018); alterations in AR occurred at similar rates (13% vs 13%, p=1.0). In liquid samples, overall BRAF GA were slightly less common (187/7566, 2.5%): 65 (0.9%) RE, 33 (0.4%) K601E, 12 (0.2%) G469A. Examining BRAF-altered samples across all cancer types, aPC had the highest proportions of RE (46%) and one of the lowest frequencies of V600E (0.1%). Conclusions: Activating BRAF alterations are detected in ~3% of aPC, with frequent BRAF-SND1 fusions. BRAF RE represent almost half of aPC BRAF GA, the highest fraction observed across a pan-tumor dataset. In addition, we detected a higher incidence of concurrent CDK12 GA and a lower relative frequency of concurrent PTEN, APC, and TMPRSS2-ERG GA. These findings suggest that genetic activation of BRAF in aPC pts may contribute to tumorigenesis and supports further clinical investigation of therapeutics targeting the MAPK pathway in this molecular subtype.

Impact of race and payor status on patterns of utilization of partial and radical nephrectomy in patients with localized renal cell carcinoma (RCC)

614

Background: Racial minorities experience intersecting forms of marginalization and suffer significant healthcare disparities. Prospective trials have shown similar outcomes with partial and radical nephrectomy among patients with localized RCC (Van Poppel et al Eur Urol 2011), and multiple studies suggest increasing use of the former technique (Breau et al Can J Urol 2020). We hypothesize that patients from minority groups, as well as those with non-private insurance, will have less access to this specialized procedure and therefore have a higher rate of radical nephrectomy. Methods: We utilized the California Office of Statewide Health Planning and Development (OSHPD) database that collects information from all inpatient admissions, emergency room visits and inpatient/outpatient procedures in the state. All patients undergoing nephrectomy (both partial and radical) were identified from Jan 1, 2012 to Dec 31, 2018 using CPT and ICD-9/10 codes to identify patients. Demographic data was collected with specific attention to race and payor status. Univariate and multivariate analyses were conducted to determine the association between demographic data and procedure type. Results: In total, 31,093 patients were identified; 57% were males, with a mean age of 58 years. Among these, 16,142 (51.9%), 8,645 (27.8%), 2,795 (9.0%), 2,032 (6.5%) and 1,479 (4.8%) were characterized as White, Hispanic, Asian, Black and other, respectively. Partial nephrectomy and radical nephrectomy were performed in 15,840 (50.9%) and 15,253 (49.1%) of patients. By race, partial nephrectomy was performed in 8,576 (53.1%), 4,107 (47.5%), 1,286 (46.0%), 1,124 (55.3%) and 747 (50.5%) of White, Hispanic, Asian, Black and other patients, respectively (p<0.001). Use of partial nephrectomy also differed among patients based on payor status, with rates of 6,800 (56.4%), 5,036 (43.9%), 1,817 (38.3%) and 2,187 (77.7%) among patients with private, Medicare, indigent coverage (e.g., MediCal or Medicaid) and other insurance, respectively (p<0.001). On multivariate analysis controlling for age, gender, comorbidities and frailty, race was independently associated with type of nephrectomy procedure. Conclusions: Our study confirms that race and payor status may have an influence on utilization of partial versus radical nephrectomy, with the highest rate of partial nephrectomies among Whites and patients with private insurance. Although there are multiple potential confounders (e.g., latency of diagnosis and resulting tumor size/complexity), it is possible that access to care may be an important driver of these disparities.

Evaluation of eligibility criteria in contemporary renal cell carcinoma based on ASCO-FCR recommendations

612

Background: A consensus statement from the American Society of Clinical Oncology (ASCO) and Friends of Cancer Research (FCR) collaboration highlights the importance of expanding eligibility criteria in cancer trials to more accurately reflect the real-world population (Kim et al., Clin Cancer Res 2021). We sought to characterize use of overly restrictive eligibility criteria in renal cell carcinoma (RCC) trials in the context of ASCO-FCR recommendations. Methods: Studies containing the MeSH terms “(metastatic OR advanced OR stage IV or unresectable) AND (kidney cancer OR renal cell carcinoma OR renal cell cancer)” from June 30, 2012 to June 30, 2022 were identified on the ClinicalTrials.gov platform. Our search query’s inclusion criteria identified international studies examining adult patients aged ≥ 18 in phase I-III trials. Exclusion criteria comprised pan-cancer studies, trials involving localized treatments, radiation therapy, and prognostic tools. Descriptive statistics were used to characterize the frequency of restrictive eligibility criteria across studies, while Fisher’s exact test or chi-square test were utilized to determine the association between treatment type and exclusion criteria. Results: The content of 423 RCC trials were analyzed, of which 112 (26.5%) had adequate data available. 48 (42.9%), 44 (39.3%) and 18 (16.1%) studies examined combination therapy, targeted therapy, and immunotherapy, respectively. The presence of HIV positivity, HBV/HCV positivity, brain metastases, and concurrent malignancies accounted for the most frequently cited exclusionary criteria, seen in 83/112 (74.1%), 60/112 (53.6%), 37/112 (33.0%), and 9/112 (8.0%) studies respectively. Differences in the use of HIV positivity (p<0.001) and HBV/HCV positivity (p<0.001) as eligibility criteria were observed across classes of therapy (see Table). Conclusions: A significant proportion of RCC studies utilize overly restrictive eligibility criteria as highlighted by the ASCO-FCR joint statement. Appropriate broadening of eligibility criteria to incorporate patient populations mirroring a real-world setting will provide more useful data going forward. [Table: see text]

Characterization of clinical outcomes among patients with advanced chromophobe renal cell carcinoma (ChRCC) treated with first-line immunotherapy (IO)-based regimens

654

Background: IO-based regimens have demonstrated substantial efficacy in the management of metastatic clear-cell RCC (mccRCC), where they currently represent the standard of care. ChRCC has a dismal prognosis in the metastatic setting. Recent clinical trials evaluating IO-based regimens across non-ccRCC subtypes identified a preliminary poor response in advanced ChRCC, but were limited by low sample sizes. We sought to comprehensively evaluate the outcomes of patients with ChRCC treated with IO-based regimens. Methods: Using real-world data from the International Metastatic RCC Database Consortium (IMDC), we conducted a retrospective analysis of patients with advanced ChRCC who received IO-based therapies, including dual IO therapy or IO + VEGF targeted therapy (VEGF-TT), in the first-line setting. The primary outcome was overall survival (OS). Secondary outcomes included time to treatment failure (TTF) and ORR. Cox proportional hazards models were used to adjust for age and IMDC risk groups as covariates. A logistic regression was used to determine the association between the odds of achieving a response and RCC subtype. Results: We identified 31 patients with advanced ChRCC and 856 patients with ccRCC treated with IO-based therapies in the first-line setting, with a median age of 61.5 years (IQR: 51.5-69.0). Compared to patients with ccRCC who received IO-based therapies as initial regimens, patients with ChRCC had a lower OS (median OS: 24.7 vs. 50.5 months, respectively; p<0.001) and a lower TTF (median TTF: 4.5 vs. 11.0 months, respectively; p<0.001). Among patients with an evaluable objective response, the ORR was lower among patients with advanced ChRCC, as opposed to those with ccRCC (ORR: 12.0 vs 47.1%, respectively; p<0.001). When evaluating first-line treatment with VEGF-TT monotherapy (sunitinib or pazopanib), no difference in outcomes was found between patients with ChRCC (n=122) and ccRCC (n=6,379) in relation to the primary endpoint of OS, while TTF and ORR suggested better outcomes for ccRCC (Table). Conclusions: In this real-world study, patients with metastatic ChRCC appear to display poor clinical outcomes even with IO-based regimens, as compared to ccRCC. The molecular determinants of poor response require further investigations. [Table: see text]

Prevalence of dietary modification and supplement use in patients with metastatic renal cell carcinoma (mRCC)

662

Background: Mounting data suggests that dietary modification and supplement use, including probiotics, may modulate outcomes with immunotherapy in cancer therapy (Spencer CN et al. Science 2021; Dizman N et al. Nature Medicine 2022). For the first time, we sought to quantify the use of these measures among patients with metastatic renal cell carcinoma (mRCC). Methods: An online survey was administered by Kidney Cancer Research Alliance (KCCure), a non-profit patient advocacy group, between July 22 and Sept 22 to a patient mailing list (N=1,532). Only patients diagnosed with mRCC and under active systemic therapy were included for analysis in the current study. Select questions were directed at dietary modification patterns and supplement usage. Patients were additionally surveyed regarding out-of-pocket spending patterns related to supplement purchases and to what extent they shared information about their supplement intake with their physicians. The student's t-test and Chi-square test were used to compare sociodemographic characteristics between participants who did and did not report supplement intake. Results: Out of 1,062 patients with renal cell carcinoma who participated in this survey, 289 met the inclusion criteria (M:F, 145:143). The median age was 61. The majority of patients identified themselves as white (91%), were from the US (86.8%), and had completed a bachelor's degree (52.9%). 21.1%, 46.1%, and 32.6% lived in urban, suburban, and rural locations, respectively. The most common reported first-line treatments were nivolumab/ipilimumab (32.4%) and axitinib/pembrolizumab (13.1%). 22.4% of respondents reported spending >$100/month on supplements, and 8.3% reported spending >$250/mo. Dietary modifications following a cancer diagnosis were reported by 34.9% of respondents, out of which 19.8% followed the Mediterranean diet and 18.8% adopted a ketogenic diet. 50.8% of respondents reported supplement intake. The most widely utilized supplements were cannabidiol (CBD) oil/marijuana, probiotics, and Vitamin C, reported by 28.0%, 24.2%, and 18.6% of respondents, respectively. 83.4% of respondents noted that they consistently report supplement usage to their physicians. There were no statistically significant associations between supplement use and age, sex, living area, or education. Conclusions: A substantial proportion of patients with mRCC use dietary modification and supplements as an adjunct to their antineoplastic treatment. Interventions such as probiotic use and ketogenic diets, which are the subject of a prospective study in mRCC (NCT05119010; NCT05122546), may already be used by many patients. More careful attention to nutrition and supplement use in clinical trial candidates may minimize the impact of these potential confounders.

Association between time-of-day of the immune checkpoint inhibitor (ICI) infusion and disease outcomes among patients with metastatic renal cell carcinoma (mRCC)

678

Background: Recent studies have suggested an association between the time-of-day of ICI infusions and disease outcomes, including progression free survival and overall survival, among patients with cancer. (Qian et al Lancet Oncology 2021). We sought to identify whether such an association exists in patients with mRCC receiving ICIs. Methods: Patients with mRCC treated with nivolumab alone, or in combination with ipilimumab, in either first- or second-line treatment were retrospectively identified. Patients who received <25% of infusions after 4:30 pm were assigned to the early time of infusion (TOI) sub-cohort while patients who received ≥ 25% of infusions after 4:30 pm were assigned to the late TOI sub-cohort. Objective response rate (ORR, per RECIST 1.1), time to treatment failure (TTF, defined as time from the date of first ICI infusion to time of treatment discontinuation), and overall survival (OS) were compared across the two groups using Cox proportional hazard models before and after adjustment for potential confounders (age, gender, line of treatment, IMDC risk, and histologic subtype). Results: A total of 145 mRCC pts (M:F,102:43) were included in the analysis. Median age was 64 (range 31-89) years, 81.4% had clear cell histology, and 75.9% had intermediate/poor risk disease. Early TOI sub-cohort included 110 (75.9%) patients while late TOI sub-cohort included 35 (24.1%) patients. Baseline characteristics were comparable across the two groups. Median OS for the entire cohort was 41.7 months (95% CI, 33.0 – Not reached [NR]), with a median TTF of 6.5 months (95% CI, 5.0 – 10.8). ORR was 32.7% in early TOI sub-group versus 25% in late TOI sub-group (p=0.60). Median TTF for the early TOI sub-cohort was 8.3 months (95% CI 6.0 – 12.6), as compared to 4.4 months (95% CI 2.1 - 10.8) among the late TOI group with a hazard ratio (HR) of 0.79 (95% CI, 0.50 – 1.25; p=0.32). Multivariate analysis showed a HR of 1.55 (95% CI, 0.98 – 2.57; p=0.06) after adjustment for potential confounders. The median OS was 46.3 months (95% CI, 32.2 – NR) in early TOI sub-cohort versus 41.7 months (95% CI, 16.7 – NR) in late TOI sub-group with a HR of 0.67 (95% CI 0.37 – 1.23; p=0.20) in univariate analyses and 0.61 (95% CI 0.33 – 1.15; p=0.13) in multivariate analyses. Conclusions: Our results demonstrated a numerical increase in ORR, TTF and OS with early TOI compared to late TOI, with the TTF difference approaching significance after adjustment for potential confounders. Larger randomized and controlled investigations are warranted to examine the impact of chronomodulation on the efficacy of ICIs in cancers, including mRCC.

Assessment of eligibility criteria in advanced urothelial cancer (aUC) trials based on ASCO-FCR recommendations

453

Background: American Society of Clinical Oncology (ASCO) and the Friends of Cancer Research (FCR) underscored the need to broaden eligibility criteria in cancer trials to increase patient accrual, expand access to investigational treatments, and enhance generalizability of study results (Kim et al., Clin Cancer Res 2021). While eligibility criteria intend to prioritize patient safety and define a specific study population, these criteria are often based on outdated standards and may not be reflective of real-world practice. Our study aimed to characterize the proportion of aUC trial eligibility criteria according to the ASCO-FCR statement. Methods: Protocols indexed on ClinicalTrials.gov with start dates from June 30, 2012 to June 30, 2022 were evaluated. MeSH terms used in our query were “(metastatic OR advanced OR stage IV OR unresectable) AND (bladder cancer OR upper tract urothelial carcinoma OR upper tract urothelial cancer)”. International studies enrolling patients aged 18 and over in phases I-III were included. Studies examining multiple cancer types as well as those involving localized treatments (e.g., surgery or ablation), radiation therapy, and prognostic tools were excluded. Analyses of eligibility criteria focused on those highlighted in the ASCO-FCR statement; descriptive statistics were used to define the frequency of eligibility criteria and chi-square and Fisher’s exact test were used to determine their association with treatment type. Results: Overall, 205 urothelial cancer trials were assessed, with 37 (18.0%) having publicly accessible data. Of these, 13 (35.1%) evaluated combination therapy, 11 (29.7%) evaluated immunotherapy, 8 (21.6%) evaluated targeted therapy, and 5 (13.5%) evaluated chemotherapy. HIV positivity, HBV/HCV positivity, brain metastases, and concurrent malignancies were found to be exclusion criteria in 89.2% (33/37), 56.8% (21/37), 35.1% (13/37), and 5.4% (2/37) of studies, respectively. While brain metastases, concurrent malignancies, and HBV/HCV positivity were found to be independent of the class of therapy, a statistically significant association was observed with HIV positivity. Specifically, trials evaluating combination therapy (100.0%), immunotherapy (100.0%) and targeted therapy (87.5%) more frequently included HIV positivity as an exclusion criterion as compared to chemotherapy trials (40.0%). Conclusions: A modest percentage of a UC studies from the last decade were observed to report overly restrictive eligibility criteria as defined by the ASCO-FCR statement. HIV positivity and HBV/HCV positivity were commonly identified exclusion criteria, despite limited evidence that these criteria significantly impact drug efficacy and tolerability. Reassessing and updating eligibility criteria will ensure that the resulting data is more reflective and inclusive of a real-world population.

Outcomes of patients with brain metastases from renal cell carcinoma treated with first-line therapies: Results from the International Metastatic Renal Cell Carcinoma Database Consortium (IMDC)

600

Background: The outcomes of patients with brain metastases from renal cell carcinoma (RCC) are not well characterized due to exclusion of these patients from clinical trials. Methods: Using the IMDC, patients with brain metastases from RCC at the initiation of first-line therapy were analyzed. Baseline patient characteristics, brain-directed local therapies, clinician assessment of best overall response as per RECIST 1.1, and overall survival (OS) were compared across first-line therapies, namely immuno-oncology (IO)-based combination therapy (IO/IO or IO/vascular endothelial growth factor (VEGF)) and anti-VEGF monotherapy (sunitinib or pazopanib). Results: The overall cohort of patients with brain metastases included 775 patients, consisting of 78/1298 (6.0%) and 697/8633 (8.1%) in the IO-based and anti-VEGF cohorts, respectively (p = 0.009). Among the baseline patient characteristics, only the proportion of patients receiving whole-brain radiotherapy differed significantly across the IO-based and anti-VEGF cohorts with proportions of 25.0% and 55.7%, respectively (p < 0.001). Best overall response in all disease sites was 3.4% complete response (CR), 25.9% partial response (PR), 39.7% stable disease (SD), and 31% progressive disease (PD) in the IO-based cohort, whereas it was 0.7% CR, 29.6% PR, 36.7% SD, and 33.0% PD in the anti-VEGF cohort (p = 0.223). The following factors were significantly associated with longer OS on multivariable analysis: IMDC favourable-/intermediate-risk (HR 0.49, 95% CI 0.37–0.65; p < 0.001), IO-based combination therapy (HR 0.51, 95% CI 0.29–0.92; p = 0.026), neurosurgery (HR 0.62, 95% CI 0.47–0.83; p = 0.001), and stereotactic radiosurgery (HR 0.64, 95% CI 0.49–0.84; p = 0.001). Conclusions: Patients with brain metastases receiving IO-based combination therapy may have longer OS than those receiving anti-VEGF monotherapy. Brain-directed local therapies including neurosurgery and stereotactic radiosurgery were associated with longer OS. [Table: see text]

Evaluation of eligibility criteria in advanced prostate cancer clinical trials based on ASCO-FCR recommendations

34

Background: The American Society of Clinical Oncology (ASCO) and the Friends of Cancer Research (FCR) published a joint statement addressing clinical eligibility for characteristics lacking adequate representation in recent studies (Kim et al., Clin Cancer Res 2021). Herein, we aimed to identify the frequency of other potentially excessive exclusion criteria in the context of metastatic prostate cancer. Methods: The eligibility criteria of advanced prostate cancer studies with start dates between June 30, 2012 and June 30, 2022 were identified through Clinicaltrials.gov. MeSH (Medical Subject Headings) terms in our query were “(metastatic OR advanced OR stage IV OR unresectable) AND (prostate cancer OR prostate adenocarcinoma)”. Our study included trials conducted worldwide and examined patients aged 18 and over in phase I-III trials. To narrow the scope of study, trials including more than one cancer type (basket trials) as well as those focusing on radiation therapy were not included in the study. Descriptive statistics were used to determine the frequency of eligibility criteria while the Fisher’s exact test or chi-square test were performed to demonstrate association between type of treatment and exclusion criteria. Results: 265 of 699 (37.9%) clinical trials within the specified search had sufficiently available data for evaluation. Of these, 136 (51.3%), 51 (19.2%), 26 (9.8%), 20 (7.5%), 19 (7.2%), and 7 (2.6%) of trials investigated treatment with combination therapy, hormone therapy, targeted therapy, immunotherapy, radioligand therapy, and chemotherapy, respectively. The most common ASCO-FCR-cited exclusion criteria in the studies were brain metastases (161/265, 60.8 %), HIV positivity (123/265, 46.4%), HBV/HCV positivity (122/265, 46.0%), and concurrent malignancies (41/265, 16.6%). Statistically significant relationships were identified between type of treatment along with status of brain metastases, HIV, and HBV/HCV (p=0.011, <0.001, and 0.001, respectively. Conclusions: This study represents the first effort to analyze this specific subset of exclusion criteria in relation to type of treatment in advanced prostate cancer. Attention to the ASCO-FCR consensus statement may maximize patient representation in future studies and increase generalizability of data. [Table: see text]

Abstract 6293: Genomic characteristics of nivolumab/ipilimumab with or without CBM-588 supplementation in patients with metastatic renal cell carcinoma

Background: In a previous randomized phase I trial, addition of CBM-588 to the nivolumab/ipilimumab (N/I) regimen showed improved objective response rate, clinical benefit rate, and progression free survival compared to N/I alone in patients (pts) with metastatic renal cell carcinoma (mRCC; Meza et al., ASCO 2021). Furthermore, genomic alterations such as PBRM1 have been associated with clinical benefit to anti-PD-1 monotherapy in patients with mRCC (Miao et al., Science 2018). The primary aim of this study was to investigate tumor genomic characteristics according to treatment arms.

Methods: We retrospectively identified pts with mRCC who received N/I alone or with CBM-588 supplementation along with whole exome and transcriptome sequencing (Ashion Analytics). Responses were measured according to RECIST v1.1. A two-tailed Fischer’s exact test was performed to compare genomic characteristics across arms.

Results: In this study, 29 mRCC pts were randomized to receive N/I +/- CBM-588 and 21 (72%) pts (71% in N/I with CBM-588 arm and 29% N/I arm) had available genomic data. Within this cohort, the median age was 66.8 (range 46-90) and 71% of pts were male. Eleven (52.4%) pts had clear-cell histology and 10 (47.6%) pts had sarcomatoid features; 15 pts received N/I with CBM-588 and 6 pts received N/I alone. The most commonly mutated genes in the overall cohort were VHL (61.9%), PBRM1 (42.9%), and SETD2 (33.3%). Alterations in VHL, PBRM1, and SETD2 were seen in 66.7% vs. 73.3% (p=0.115), 50.0% vs. 40.0% (p=0.523) and 33.3% vs. 33.3% (p=0.686), in N/I vs. N/I with CBM-588 arm, respectively.

Conclusions: There was no significant difference observed in clinically relevant genomic features across study arms. The clinical benefit from CBM-588 appears to be independent of tumor genomic characteristics. More extensive investigations are needed to characterize the determinants of benefit from CBM-588 supplementation.

Citation Format: Daniela V. Castro, Nazli Dizman, Zeynep B. Zengin, Jasnoor Malhotra, Luis A. Meza, Ramya Muddasani, Ameish Govindarajan, Neal S. Chawla, Alex Chehrazi-Raffle, JoAnn Hsu, Paulo G. Bergerot, Cristiane D. Bergerot, Tanya B. Dorff, Yung Lyou, Sumanta K. Pal. Genomic characteristics of nivolumab/ipilimumab with or without CBM-588 supplementation in patients with metastatic renal cell carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 6293.

Distinct outcomes in Hispanic/Latinx and non-Hispanic/Latinx patients with metastatic renal cell carcinoma (mRCC) treated with first-line ipilimumab plus nivolumab (ipi/nivo)

4554

Background: Subgroup analyses have reported differences in clinical outcomes by ethnicity in patients (pts) receiving immune checkpoint inhibitors (Cheng et al Ann Oncol 2019; Peravali et al World J Clin Oncol 2021). We sought to compare real-world outcomes between Hispanic/Latinx and non-Hispanic/Latinx mRCC pts treated with first-line ipi/nivo within a safety-net healthcare system and at a tertiary care center in Southern California. Methods: We performed a retrospective analysis of mRCC pts who received ipi/nivo within the Los Angeles County Department of Health Services (a safety-net healthcare system) and the City of Hope Comprehensive Cancer Center (a tertiary oncology center) between Jan 1, 2015 and Dec 31, 2021. Pts were identified using institutional databases and clinical data were compiled from electronic health records. Pts with pathologic diagnosis of stage IV mRCC, age > 18 years and receipt of ipi/nivo as first-line therapy were included. Progression-free survival (PFS) was analyzed using the Kaplan-Meier method and covariates were adjusted using multivariate Cox proportional hazards regression. Results: Of 96 pts, 67 (70%) were male, 90 (94%) had clear-cell histology, and 89 (93%) had intermediate/poor IMDC risk. Forty-two pts (44%) were Hispanic/Latinx while the remainder were non-Hispanic/Latinx (44 pts [46%] White, 7 pts [7%] Asian, and 3 pts [3%] Other). Fifty (52%) and 46 (48%) pts received their care at a tertiary care center and within a safety-net healthcare system, respectively. Median age, IMDC risk classification, BMI, and number of comorbidities were similar between both groups. Pooled analysis by ethnicity revealed significantly shorter PFS in Hispanic/Latinx vs non-Hispanic/Latinx pts (HR 1.60, 95% CI 1.04-2.48, p = 0.03). At 12 months, 19% of Hispanic/Latinx pts (95% CI, 9-32) and 35% of non-Hispanic/Latinx pts (95% CI, 23-48) were alive and progression-free. There was no difference in PFS between pts at the safety-net hospital system vs tertiary care center (HR 1.32, 95% CI 0.87-2.02, p = 0.19). Conclusions: Our real-world analysis of mRCC pts demonstrated poorer outcomes with ipi/nivo in Hispanic/Latinx pts. We are currently interrogating multiple social determinants of health that may contribute to these concerning disparities.

A phase I trial to evaluate the biologic effect of CBM588 (Clostridium butyricum) in combination with cabozantinib plus nivolumab for patients with metastatic renal cell carcinoma (mRCC)

TPS4606

Background: Combination therapy with the immune checkpoint inhibitor (ICI) nivolumab (nivo) and the tyrosine kinase inhibitor cabozantinib (cabo) is a new standard of care for first line treatment of patients with clear cell mRCC. However, despite the improved clinical benefit obtained with this regimen, a subgroup of patients still presents with progressive disease as best response (Choueiri et al NEJM 2021). There is now evidence supporting the role of the gut microbiome in mediating ICI activity (Routy et al Science 2018) and certain bacterial species, such as Bifidobacterium spp. in predisposing clinical response in patients with mRCC receiving ICIs (Salgia et al Eur Urol 2020). Moreover, recent evidence from a phase I clinical trial suggests that the addition of CBM588, a live probiotic comprised primarily of Clostridium butyricum, can enhance clinical response in patients with mRCC receiving nivolumab plus ipilimumab without incurring added toxicity (Meza et al ASCO, 2021). Herein we present the study design of an ongoing phase I study evaluating the biological effect of CBM588 in combination with cabozantinib plus nivolumab in patients with mRCC. Methods: This is an open label, randomized, single institution phase 1 trial for patients with confirmed mRCC with clear cell, papillary, or sarcomatoid components, who have not received prior systemic therapy for metastatic disease. A total of 30 eligible patient will be randomized 1:2 to receive either cabo/nivo at the standard dose/schedule (40mg PO QD and 480mg IV /4wks, respectively) alone or with CBM588 dosed at 80mg PO bid. The primary objective of the study is to determine the biologic effect of CBM588 with cabo/nivo in the modulation of the gut microbiome. This will be done by assessing the changes in Bifidobacterium spp. abundance and Shannon index (a measure of microbiome diversity) in stool specimens. Stool will be collected for bacteriomic profiling at baseline and after 12 weeks of treatment. Metagenomic sequencing will be performed using previously published methods (Dizman et al Cancer Med 2020). Secondary objectives include determining the effect of CBM588 on (1) clinical efficacy, through overall survival, response rate, and progression-free survival; (2) systemic immunomodulation, through assessment of changes in circulating Tregs, circulating cytokines/chemokines, etc; and (3) toxicities. A two-group t-test with a one-sided type I error of 0.05 will be used to assess the study primary endpoint. Clinical trial information: NCT05122546 .

Transcriptomic profiling identifies genomic markers associated with benefit from stereotactic body radiation therapy (SBRT) in oligoprogressive metastatic renal cell carcinoma (mRCC)

4555

Background: Addition of SBRT to systemic therapy in oligoprogressive mRCC has been shown to prolong the duration of systemic treatment (Cheung et al Eur Urol 2021; De et al BJUI 2021). To date, the genomic predictors of benefit are unknown. We hypothesized that hypoxia-related genes would be associated with lesser benefit from SBRT. Methods: We retrospectively identified patients (pts) with mRCC who had oligoprogressive disease (progression of < 5 sites) while on systemic treatment and received SBRT without any systemic treatment change or interruption. Clinicopathologic characteristics, whole exome and transcriptome sequencing (Ashion Analytics) data were collected. Duration of systemic therapy (DOT) was quantified as systemic treatment duration prior to oligoprogression (DOT[P]) and after completion of SBRT (DOT[S]). The ratio of DOT[S]/DOT[P] was calculated and patients with a ratio ≥ 1.0 were considered to derive greater benefit from SBRT. The frequency of specific DNA alterations and RNA expression of pts above and below a DOT[S]/DOT[P] threshold of 1.0 was compared using a two-tailed Fischer’s exact and student’s t-test, respectively. Results: In this study, 23 mRCC pts who had oligoprogression during systemic treatment and received SBRT were identified. Within this cohort 16 pts (69.6%; M:F, 12:4) had available genomic data. Median age was 70 years and the most common histology was clear cell (87.5%). At the time of oligoprogression 11 pts (68.8%) were on immunotherapy, 4 pts (25.0%) were on targeted therapy. Median DOT[S] and DOT[P] were 12.6 months (range,0.7-46.3) and 13.4 months (range, 0.5-26.9), respectively, with a median DOT[S]/DOT[P] ratio of 1.4 (range,0.01-3.8). The most commonly mutated genes were VHL (56.3%), PBRM1 (37.5%), and SETD2 (37.5%). Alterations in VHL, PBRM1 and SETD2 were seen in 66.7% vs 42.9%, 33.3% vs 43.9%, and 44.4% vs 28.6% in patients with greater vs lesser benefit from SBRT, respectively (p≥0.05for each). Transcriptomic analysis was available in 9 pts and 1580 genes were noted to be differentially expressed between the groups (p < 0.05). Limiting scope to cancer genes in the COSMIC database, pts with lesser benefit from SBRT had higher expression of CDKN1B, CNBP, and FOXO3 whereas pts with greater benefit had higher expression of RNF43, POLD1 and PBRM1 (p < 0.05 for each). Gene set enrichment analysis showed a trend towards increased expression of hypoxia related genes in pts with lesser benefit. Conclusions: Our data align with existing studies supporting the role of SBRT in oligoprogressive mRCC. In addition, while clinical benefit from SBRT appears to be independent of DNA-level alterations, transcriptomic analysis revealed significant differences in gene expression. Hypoxia-associated signatures may be associated with lesser benefit from radiotherapy.

Characterization of the microbial resistome in a prospective trial of CBM588 in metastatic renal cell carcinoma (mRCC) offers mechanism for interplay between antibiotic (abx) use and immune checkpoint inhibitor (ICI) activity

4510

Background: The negative association between ICI response and abx therapy is well defined (Derosa et al Cancer Discov 2021). Paradoxically, a retrospective assessment of the live bacterial product (LBP) CBM588 in patients (pts) with advanced lung cancer showed improved outcome with ICIs when the combination of CBM588 and abx (as compared to CBM588 alone) was employed (Tomita et al Cancer Immunol Res 2020). We postulated that the microbial resistome (genes encoding antimicrobial resistance) could shift in a manner with CBM588 therapy that facilitated ICI response. Methods: Pts with newly diagnosed mRCC with clear cell and/or sarcomatoid histology and intermediate/high risk disease per IMDC criteria were randomized to nivolumab/ipilimumab (nivo/ipi) or nivo/ipi/CBM588 in a 1:2 ratio. Stool samples were collected at baseline and week 12. Whole-metagenome sequencing was performed to analyze stool microbiome composition. Abx resistance genes (RGs) were inferred using publicly available database (McArthur et al. Antimicrob Agents Chemother 2013), and groups of abx RGs for various classes of abx were characterized. Wilcoxon signed-rank test was used for comparison of abx RG abundance between baseline and week 12 in each treatment arm and in responders (R) and non-responders (NR). Results: The study enrolled 30 pts, with the final analysis including 29 eligible pts (median age: 66 years, M:F 21:8, nivo/ipi: 19 pts, nivo/ipi/CBM588:10 pts). Objective response was 20% and 58% in nivo/ipi and nivo/ipi/CBM588 arms, respectively. The overall abundance of abx RGs remained unchanged between baseline and week 12 in pts receiving nivo/ipi alone. In contrast, a decrease in abx RGs was observed in pts receiving nivo/ipi with CBM588 arm from baseline to week 12 (p = 0.042 in Rs; p = 0.078 in NRs). More specifically, nivo/ipi/CBM588 treatment led to a significant reduction in fosfomycin RGs and nitroimidazole (e.g., metronidazole) RGs in both pts with R (p = 0.019 and 0.042, respectively) and NR (p = 0.031 and p = 0.031, respectively). A multitude of other clinically relevant abx RGs were downregulated in pts receiving CBM588, including those mediating resistance to glycopeptide (e.g., vancomycin) and lincosamide (e.g., clindamycin) abx. Conclusions: In the first interrogation of the resistome in mRCC, we demonstrate that CBM588 decreases abx RGs associated with multiple commonly used classes of abx. Abx clear commensals and increase pathogenic (abx resistant) bacteria in the gut. Based on our data, we formulate the hypothesis that combining abx with CBM588 may decrease potentially pathobionts and favor butyrogenic species, thereby improving CPI response. Clinical studies using CBM588 with abx priming may be warranted. Clinical trial information: NCT03829111.

Characterization of aberrant alternative splicing landscape in patients with renal cell carcinoma (RCC)

386

Background: Aberrant alternative splicing (AS) events have been implicated in the initiation and progression of various cancers; however, the detailed nature of their role in RCC is yet to be fully elucidated. Our study aims to characterize AS events in RCC tumors using a novel AS pipeline (Bisbee). Methods: We retrospectively identified patients (pts) with RCC who had tumor-normal whole exome sequencing and tumor whole transcriptome sequencing (GEMExtra, Ashion Analytics) performed as part of their routine clinical care. AS events from RNA sequencing data were identified and further characterized as (1) alternative splice 3’ site (A3), (2) alternative splice 5’ site (A5), (3) exon skipping (ES), (4) intron retention (IR), and (5) mutually exclusive exons splice events (MUT). The Bisbee outlier analysis was performed against normal kidney tissues from the GTEx tissue library to further identify tumor-associated splice events. Outlier splice events were categorized as either non-coding/protein loss/silent, isoform switch, novel, or unknown. Results: Overall, 147 RCC pts (77% male) with RNA sequencing data were included in this analysis. Median age at diagnosis was 60 (range 31-94) and 97% of pts had metastatic RCC. The distribution of histology was 85% clear cell RCC followed by 11% papillary RCC. The AS analysis identified 25,928 outlier splice events. Approximately 60% of these were predicted to be protein-coding events, with the majority arising from IR and ES. These were followed by A3, A5, and MUT, in descending order of frequency. We also examined tumor-associated novel outlier events where 70% of analyzed RCC tumor samples noted 34 tumor-associated novel events were present, shared in most of the cohort and found an enrichment for IR events leading to frame disruptions. Data of splice variants will be presented at the meeting. Conclusions: In depth examination of this large cohort suggests that IR resulting from AS events occur frequently within RCC. Further efforts to investigate the association of AS events and clinical outcomes are underway.

Predictors of objective response to first-line immuno-oncology combination therapies in metastatic renal cell carcinoma: Results from the international metastatic renal cell database consortium (IMDC)

310

Background: Predictors of objective response to first-line (1L) immuno-oncology (IO) combination therapies remain elusive. We sought to characterise clinical variables and their association with investigator assessed best overall response. Methods: Using the IMDC, we retrospectively identified patients treated with 1L ipilimumab nivolumab (IPI-NIVO) or approved IO/vascular endothelial growth factor (VEGF) inhibitor combinations (IOVE). Patients were classified, per RECIST v1.1, as responders (complete or partial response (CR or PR)) or non-responders (stable or progressive disease (SD or PD)). Logistic regression was used to adjust for IMDC criteria. Results: Out of 1084 patients, 794 (73%) received IPI-NIVO and 290 (27%) received IOVE (axitinib+pembrolizumab, cabozantinib+nivolumab, axitinib+avelumab, lenvatinib+pembrolizumab). Favourable, intermediate and poor IMDC risk comprised 147 (16%), 517 (55%) and 272 (29%) respectively. Of the 898 patients with evaluable responses, 37 (4%) achieved a best response of CR, 343 (38%) PR, 315 (35%) SD and 203 (23%) PD. Corresponding median overall survival from time of 1L initiation was: not reached, 55.9, 48.1, and 13 months respectively (logrank p < 0.0001). In a multivariable model, lung metastases and cytoreductive nephrectomy (CN) (performed after diagnosis of metastatic disease and before 1L therapy) retained independent association with response, after adjustment for IMDC criteria. Factors not associated with response included (with univariable p values): gender (p = 0.58), age (p = 0.06), sarcomatoid histology (p = 0.99), smoking status (p = 0.39), liver (p = 0.63) and brain (p = 0.12) metastases. As in the VEGF monotherapy era, improved IMDC prognostic risk was associated with response. Results were similar when restricted to the IPI-NIVO cohort. Conclusions: Presence of lung metastases, CN and better IMDC risk group are associated with a higher probability of response to 1L immunotherapy combination regimens. Further work to identify reliable predictors of response to guide treatment selection and patient counselling is warranted.[Table: see text]

Nivolumab/ipilimumab with or without CBM588 in metastatic renal cell carcinoma: A randomized phase Ib study and the evolution of the functionality of microbial communities with treatment

371

Background: The role of gut microbial composition as a determinant of clinical outcomes has been well established in several cancers, including metastatic renal cell carcinoma (mRCC) (Routy et al Science 2018). A growing body of evidence suggests that examining the metabolic function of microbial communities may provide a more insightful understanding of these associations (Helmink et al Nature Medicine 2019). Herein, we aimed to examine the effect of nivolumab/ipilimumab with or without CBM588 on clinical outcomes and gut microbiome functionality. Methods: Treatment naïve mRCC pts with clear cell and/or sarcomatoid histology and IMDC intermediate/high risk disease were enrolled and randomized into receiving nivolumab/ipilimumab or nivolumab/ipilimumab with CBM588 in 1:2 fashion. Whole metagenome sequencing was performed on stool samples collected at baseline and week 12. Generated MetaPhlan 3.0 data was run through HUMAnN 3.0 to identify differentially expressed metabolic pathways between two timepoints in each arm and with respect to treatment response. Results: A total of 30 pts were enrolled and randomized, and 29 pts were eligible for analysis as one patient was excluded as tumor tissue next-generation sequencing revealed genomic alterations pathognomonic for sarcoma after initiation of protocol-based therapy. Median age of the participants was 66 years, 21 pts (72%) were male, 10 pts (34%) had sarcomatoid features, and 29 pts (45%) had prior nephrectomy. Objective response was achieved in 58% and 20% of the pts in nivolumab/ipilimumab/CBM-588 and nivolumab/ipilimumab arm, respectively. Significant changes in 40 metabolic pathways (37 with upregulation and 3 with downregulation) in nivolumab/ipilimumab arm and 52 metabolic pathways (49 with downregulation and 3 with upregulation) in nivolumab/ipilimumab with CBM588 arm were identified. In detail, dTDP-β-L-rhamnose biosynthesis, L-lysine biosynthesis II and superpathway of pyrimidine ribonucleosides degradation pathways were found upregulated while O-antigen building blocks biosynthesis (E. coli) pathway was found downregulated after treatment with nivolumab/ipilimumab and CBM588 (p = 0.001, p = 0.007, p = 0.037, p = 0.005 respectively). Heatmaps detailing the dynamics of metabolic pathway expressions in regard to response in each arm will be presented. Conclusions: We observed an increase in the activity of the pathways associated with butyrate consumption and a resultant decrease in glycolytic dependence. Further, suppression of the pathogenic E. coli function was observed, suggesting a role for CBM588 in protection from pathogenic species. Our findings provide mechanistic evidence for the effect of the addition of CBM588 to nivolumab/ipilimumab on gut microbiome function and resultant improvement in clinical outcomes in mRCC. Clinical trial information: NCT03829111.

Association of intra-tumoral microbiome and response to immune checkpoint inhibitors (ICIs) in patients with metastatic renal cell carcinoma (mRCC)

372

Background: Multiple studies have suggested that the gut microbiome plays a modulatory role in ICI activity and that specific bacteria and/or cumulative microbial diversity may drive response in patients (pts) with mRCC (Routy et al Science 2018; Salgia et al Eur Urol 2020). Even though the tumor microenvironment has substantial bacterial proliferation (Heymann et al Cancer L. 2021), there is a paucity of data assessing the impact of intra-tumoral microbiota in response to ICI therapy. In this study, we sought to explore this association in pts with mRCC. Methods: Pts diagnosed with mRCC who had available RNA sequencing (RNA-seq) data collected in the course of routine clinical care and who were treated with ICIs were retrospectively identified.Intra-tumoral microbiome analysis was performed on formalin-fixed paraffin-embedded samples. Following quality and adapter trimming, RNA-seq reads were mapped to a human genome to filter host reads using the Burrows-Wheeler alignment (BWA) tool. Taxonomic classification was performed using Kraken2 and the absolute abundances of species were estimated using Bracken. The relative abundances among all non-human species were calculated. Statistical testing with Student’s t-test was performed to compare the relative abundance for all species seen within pts who responded to ICIs and those who did not. Results: Among the 28 pts (22:6, M:F) included in this analysis, 24 (86%) had clear cell histology and 20 (71%) were IMDC intermediate/poor risk. All of the samples were collected prior to starting treatment with ICIs and the majority of these (57%) were collected from the primary site. 11 pts (39%) received ICIs as first line treatment and 17 (61%) as second line. Clinical response was seen in 50% of pts included in the study and the most common rendered treatment was nivolumab (17 pts). In the overall cohort, Cutibacterium acne, Moraxella osloensis, and Pasteurella multocida had the highest relative abundances. Additionally, significant differences in relative abundances of specific bacteria were found between ICI responders and non-responders. Among these, Stenotrophomonas maltophilia (p = 0.037) and Corynebacterium sp. zg-917 (p = 0.035) had significantly higher relative abundances in pts who responded to ICIs. Conclusions: This is the first study evaluating the association between intra-tumoral microbiome and response to ICIs in pts with mRCC. Among bacteria associated with response, several have particular relevance – for instance, Corynebacterium spp. have been studied for decades as a possible adjunct to immunotherapeutic agents such as BCG. Efforts are ongoing to validate these findings in a larger cohort.

Characterizing IMDC prognostic groups in contemporary first-line combination therapies for metastatic renal cell carcinoma (mRCC)

308

Background: The combination of immuno-oncology agents (IO) ipilimumab and nivolumab (IPI-NIVO) and combinations of IO with vascular endothelial growth factor targeted therapies (IOVE) have demonstrated efficacy in clinical trials for the first-line treatment of mRCC. This study seeks to establish real-world clinical benchmarks based on the International mRCC Database Consortium (IMDC) criteria using vascular endothelial growth factor targeted therapy (VEGF-TT) treated patients for context. Methods: The IMDC database (IMDConline.com) was used to identify patients with mRCC who received first-line IPI-NIVO, IOVE (axitinib/pembrolizumab, lenvatinib/pembrolizumab, cabozantinib/nivolumab, or axitinib/avelumab) and VEGF-TT (sunitinib or pazopanib) from 2002-2021. The primary endpoint was overall survival (OS) and was calculated from time of initiation of first-line therapy to death or last follow up. Log-rank tests were conducted to compare favorable, intermediate, and poor risk OS outcomes within treatment groups. Overall response rates (ORR) and complete response (CR) rates were calculated based on physician assessment of best clinical response. Results: In total, 692 patients received IPI-NIVO, 244 received IOVE, and 7152 received VEGF-TT. Baseline characteristics for IPI-NIVO, IOVE, and VEGF-TT, respectively, were as follows: median age (interquartile range) 63 (56-69), 64 (57-70), and 63 (56-70); male 72%, 74%, and 72% (p=0.74); non-clear cell histology 15%, 10%, and 13% (p=0.15); sarcomatoid features 24%, 15%, and 13% (p<0.0001); brain metastasis 8%, 4%, and 8% (p=0.04); liver metastasis 18%, 14%, and 18% (p=0.17); underwent nephrectomy 61%, 79% and 80% (p<0.0001). OS and ORR are reported in the table. P-values (log rank) for OS between risk groups were significant for IPI-NIVO (p<0.0001), IOVE (p=0.0005), and VEGF-TT (p<0.0001). Conclusions: These findings provide real-world survival and response benchmarks for contemporary first-line mRCC treatments and could be helpful for patient counselling. In addition, these findings mirror the efficacy of combination therapies established in clinical trials against VEGF-TT monotherapy. IMDC criteria continue to risk stratify patients in these novel combination therapies.[Table: see text]

Prolonging utilization of systemic therapy in oligoprogressive metastatic renal cell carcinoma using stereotactic body radiation therapy

336

Background: SBRT in indicated for the management of locally recurrent and oligometastatic mRCC as per National Comprehensive Cancer Network guidelines. Our study evaluates both the efficacy of radiotherapy (RT) in prolonging systemic treatment along with RT toxicity in the oligoprogressive RCC setting. Methods: A single institution retrospective data collection was performed in which we identified mRCC patients who experienced oligoprogression (defined as <1 sites of progressive disease) while on an FDA approved systemic therapy and were concurrently treated with SBRT, while remaining on the same therapy. Clinicopathologic characteristics and SBRT-related data along with duration of systemic therapy (DOT) were collected. DOT was then quantified into two categories which included the duration of systemic therapy prior to oligoprogression (DOT[P]) and duration of systemic therapy after completion of SBRT (DOT[S]). The ratio of DOT[S]/DOT[P] was calculated to determine the impact of SBRT on systemic treatment prolongation. Results: 23 patients diagnosed with mRCC meeting criteria were identified, 91% (n = 21) with clear cell histology and 9% (n = 2) with papillary histology. At the time of oligoprogression, 15 patients (65%) were on immunotherapy, 7 patients (30%) were on targeted therapy, and 1 patient (5%) was on combination therapy. We noted the preponderance of patients were on a first-line therapy at the time of oligoprogression (n = 10, 43%). A median of 2 (range, 1-3) lesions were treated per patient, with lung being the most frequent site (n = 14, 40%). The median total dose of SBRT was 30 Gy (range, 27-50 Gy) with a median dose per fraction of 6 Gy (range, 3-12 Gy). SBRT related toxicities, all of which were grade <2, were noted in 5 patients (22%), of which fatigue was the most frequent side effect (n = 3, 13%). Median DOT[S] was 13.4 months (range, 0.5-37.7 months) and the median DOT[P] was 12.8 months (range, 0.4-46.3 months). Results demonstrated a median DOT[S]/DOT[P] ratio to be 1.3 (range, 0.01-25.8). Conclusions: Based on our data, we discovered the addition of SBRT to systemic therapy during oligoprogression is not only well-tolerated, but that this treatment had clinical benefit in prolonging time on systemic therapy for patients with mRCC. The utilization of SBRT may prolong lines of therapy, thereby decreasing additional toxicities associated with exposure to new regimens.

Waning efficacy of COVID-19 vaccination at six months in patients (pts) with genitourinary malignancies

185

Background: Short-term effectiveness of COVID-19 vaccination is widely demonstrated, but the emerging real-world data suggest that immunity may wane over-time (Levin et al. NEJM 2021). Herein we aimed to explore the long-term efficacy of the COVID-19 vaccination among pts with genitourinary cancer. Methods: In this study, pts with genitourinary malignancies (prostate, kidney, and bladder cancers) who had not received COVID-19 vaccination were included. Blood samples were collected prior to and after one dose of either an adenovirus- or mRNA-based COVID-19 vaccine at the 2- and 6-month timepoints. Additional blood samples from pts receiving systemic treatment were collected at 3 consecutive therapy cycles following vaccination. Antibody titers were assessed using the SCoV-2 Detect IgG ELISA assay and results were reported as immune status ratios (ISR). T-cell receptor (TCR) repertoire sequencing was performed using the MiXCR software (MiLabs) and custom strips were used to assess TCR abundance and homology clustering. Results: A total of 183 pts were enrolled, and 136 pts provided baseline blood samples. Among these, 59 (8:51 F:M) provided samples for both the 2- and 6-month timepoints by the 10/6/2021 data cut-off. In this subset of pts, median age was 66 (range 48-85) and 33 (55.9%), 25 (42.4%), and 1 (1.7%) pts had prostate, kidney, and bladder cancer, respectively. A majority of the pts (93.2%) were on systemic treatment with 23.7% on immune checkpoint inhibitors, 18.6% on targeted agents, and 1.7% on chemotherapy. The most commonly administered vaccines were BNT162b2 (61.0%) followed by mRNA-1273 (37.3%) and Ad26.COV2.S (1.7%). The mean (±standard deviation) ISR values at baseline and 2 months were 0.68±1.59 and 6.62±1.75, respectively. At the 6-month timepoint, mean ISR was 5.46±1.61; this was significantly lower than the 2-month antibody titers (p < 0.0001), and reflects a reduction of 17.6%. Further data on TCR sequencing will be presented at the meeting. Conclusions: To our knowledge, this is the first data assessing the long-term serologic outcomes of COVID-19 vaccination in pts with cancer. Our data suggest waning immunity over time in cancer pts. Strategies to prolong host immunity against SARS COV-2 (e.g., booster vaccination) are likely warranted.

Characteristics associated with common reasons to pursue genomic profiling among patients with metastatic genitourinary cancers

327

Background: Patients with cancer may possess limited knowledge of emerging modalities in oncology, including genomic profiling (GP) tests, which can create barriers to shared decision making. Effective provider communication can address such barriers but little is understood regarding patients’ perceptions of GP. Methods: In this cross-sectional study, patients who were diagnosed with advanced genitourinary cancers (bladder, renal, and prostate cancers), and were referred for GP responded to a survey to assess reasons to pursue such testing. Clinicopathologic characteristics were collected via chart review. Kolmogorov-Smirnov tests were used to assess associations between reasons to pursue GP and patient characteristics. Results: Data was obtained from a sample of 126 patients (gender: 75% M, 25% F; average age: 67; marital status: 78% married; education: 76% some college; histology: 67% renal cell carcinoma, 19% urothelial, and 14% prostate). The most common reasons to pursue GP by patient response were: to guide treatment (73%), to improve treatment response (32%), to follow physician’s indication (27%), to predict treatment response (23%), to learn about their disease (19%), and to contribute to the science (12%). Notably, older age was significantly associated with three reasons (guide treatment, P = 0.001; physician’s indication, P = 0.03; contribute to the science, P = 0.001). No association was found among younger patients. A higher level of education was associated with the desire to guide treatment (P = 0.001). In contrast, a lower level of education was associated with physician’s indication (P = 0.002). Conclusions: This study highlights important associations between reasons to pursue GP and age and level of education. Differing strategies for information delivery could be considered when communicating GP benefits to older patients and to patients with lower levels of education.

First-line therapy for metastatic renal cell carcinoma with pancreatic metastases: Results from the International Metastatic Renal Cell Carcinoma Database Consortium (IMDC)

317

Background: Metastatic renal cell carcinoma (mRCC) with pancreatic metastases (PM) is characterised by heightened angiogenesis, which is associated with improved outcomes with vascular endothelial growth factor (VEGF) inhibitors. We aimed to compare the efficacy of first-line (1L) ipilimumab/nivolumab (IOIO) vs. anti-PD(L)1/anti-VEGF (IOVE) vs. VEGF monotherapy (VE) in mRCC patients with and without PM. Methods: We performed a retrospective analysis of patients with and without PM, using the IMDC. Sites of metastases were captured at initiation of 1L. Patients with PM could also have metastases at other sites. We studied overall survival (OS) from start of 1L therapy using Cox regression, adjusted for IMDC risk groups. Kaplan Meier survival curves were generated. Results: 543/7,634 (7%) patients had PM. Patients with PM in the overall population had improved OS compared to those without, 56 vs 25.6 months respectively (HR 0.63, 95% CI 0.55-0.73, p<0.0001). When examining the effect of PM within 1L options, those treated with IOVE exhibited a longer OS if PM were present vs absent, median not reached vs 45 months respectively (HR 0.41, 95% CI 0.18-0.93 p=0.03). This association was also seen in patients with treated with 1L VE, in those with PM vs absent, median 53.1 vs 25.1 months respectively (HR 0.65, 95% CI 0.55-0.76, p <0.0001). Contrastingly there was no difference in median OS of patients with or without PM in patients receiving IOIO, 41.4 vs 44.4 months respectively (HR 0.86, 95% CI 0.48-1.56, p=0.62). Comparing the outcomes between 1L therapies in patients with PM the median OS of IOVE vs VE was not reached vs 53.1 months respectively (HR 0.37, 95% CI 0.16-0.83 p=0.02). Conversely, upfront VE and IOIO had a similar median OS of 53.1 vs 41.4 months respectively (HR 0.81, 95% CI 0.45-1.47 p=0.49). We were unable to find any difference in OS between those treated with IOVE vs IOIO, median not reached vs 41.4 months respectively (HR 0.52 95%, CI 0.19-1.45, p=0.21), but the low event rate limited this interpretation. Conclusions: We found that the presence of PM leads to an indolent biological behavior and was associated with improved outcomes when 1L therapy included a VE component. PM patients had comparable OS outcomes on 1L VE and 1L IOIO therapy, but improved OS when treated with 1L IOVE. Anti-angiogenic therapy may be necessary to optimize outcomes in PM and this warrants prospective evaluation. [Table: see text]

CABOSEQ: The efficacy of cabozantinib post up-front immuno-oncology combinations in patients with advanced renal cell carcinoma: Results from the International Metastatic Renal Cell Carcinoma Database Consortium (IMDC)

318

Background: There are limited data to understand the activity of cabozantinib (CABO) as second line (2L) therapy post standard of care ipilimumab-nivolumab (IPI-NIVO) or immuno-oncology(IO)/vascular endothelial growth factor (VEGF) inhibitor combinations (IOVE). The activity of subsequent 3L approved therapies post CABO has not been established. Methods: Using the IMDC dataset, we examined all patients who received 2L CABO. We sought to identify the overall response rate (ORR), time to treatment failure (TTF) and overall survival (OS) of 2L CABO after IPI-NIVO, approved IOVE combinations and other 1L approaches. Additionally, we examined these outcomes for patients that received an approved 3L treatment post 2L CABO. Hazard ratios were adjusted for IMDC risk groups. Results: 346 patients were identified who had all received 2L CABO (78 post 1L IPI NIVO, 46 post 1L IOVE, 222 post 1L other). Of the entire cohort, 12.6%, 62.6% and 24.8% were IMDC favourable, intermediate and poor risk, respectively. 84% had clear cell histology, 18.5% had a sarcomatoid component and 38.3% had bone metastases at diagnosis. Outcomes for patients that received 2L CABO, stratified by 1L therapy are outlined in the table, followed by outcomes for patients that received subsequent 3L therapy post 2L CABO. After adjustment for IMDC criteria, the HR for 2L CABO OS and TTF for IOVE vs IPI-NIVO were 1.73 (95% CI 0.83-3.62 p = 0.14) and 1.62 (0.89-2.95 p = 0.11), respectively. Conclusions: There is clinically meaningful activity of CABO post IPI-NIVO, IOVE and other standard 1L approved therapies. Broadly, time to event endpoints and response rates are similar irrespective of 1L therapy. Approved systemic therapies post CABO, mainly single agent VEGF inhibitors also have activity, though as expected this is diminished compared to earlier lines of therapy. These are real world benchmarks with which to counsel our patients when using single agent CABO.[Table: see text]

Intestinal microbiome associated with development of grade 3/4 adverse in patients with metastatic renal cell carcinoma (mRCC) treated with nivolumab plus ipilimumab (N/I) and probiotic support: Results from a phase Ib study

374

Background: Treatment with N/I with the addition of CBM588, a live bacterial product comprised primarily of Clostridium butyricum, improved PFS and RR versus N/I alone when used as first line treatment for patients with mRCC (Meza et al ASCO 2021). Increased abundance of certain bacterial species in the gut microbiome have been associated with the development of treatment related adverse events (TREAs) in lung cancer patients receiving immunotherapy (Chau et al BMC Cancer 2021). However, this association has not yet been delineated in the setting of mRCC. Here, we present results of an exploratory analysis assessing the differences in stool microbiome composition between patients who experienced grade (G) 3/4 TREAs and those who did not. Methods: Patients were randomized 2:1 to receive N/I with or without CBM588. Stool collection for bacteriomic profiling was planned at baseline and after 12 weeks of therapy for all randomized patients. Whole metagenome sequencing was performed using previously published methods (Dizman et al Cancer Med 2021) and differences in microbiome composition were measured based on the occurrence of G 3/4 TREAs. Results: 30 patients were enrolled and 29 included in the study. At the time of data cutoff (April 15, 2021) the median follow up was 12.2 months (95% confidence intervals [CI], 10.6-13.8). Grade 3/4 TRAEs were experienced in 52, 50, and 53% of patients in the overall cohort, control, and intervention arms, respectively (p = NS). Among the most common G 3/4 TRAEs, subjects experienced fatigue, diarrhea, and hyperglycemia. Patients with a complete set of stool samples were included for the microbiome analysis (n = 26). In patients who experienced G 3/4 TRAEs, a significantly greater baseline abundance of Escherichia coli, Klebsiella spp. and Blautia spp. (p = 0.02, 0.03, 0.05) were seen when compared to those not experiencing G 3/4 TRAEs. In contrast, Bacteroides intestinalis and B. thetaiotamicron, were observed in significantly higher abundances in baseline stool specimens of patients who did not experience G 3/4 TREAs (p = 0.03 for both). No significant differences were seen for any of these species at the 12-week timepoint. Conclusions: We are among the first to investigate the differences in baseline stool microbiome in mRCC patients experiencing G 3/4 TRAEs while receiving immunotherapy. Our results suggest that certain taxa of bacteria are predictors of the development of serious TRAEs. Larger cohorts are needed to corroborate these findings. Clinical trial information: NCT03829111.

Changes in perception of immunotherapy over time among patients with advanced genitourinary cancers

328

Background: Previous studies have shown that a significant proportion of patients with metastatic genitourinary cancers harbor inaccurate expectations of cure prior to starting treatment with immunotherapy. This study sought to compare changes in perceptions of immunotherapy reported before, and three months after, the start of therapy, as well as treatment side-effects and quality of life. Methods: This longitudinal study enrolled patients diagnosed with advanced genitourinary cancers (bladder, renal, and prostate cancers) prior to commencing immunotherapy. Patients’ perceptions were assessed prior to starting treatment (T0) and three months later (T1). Patients responded to the same survey at both time points assessing expectations of side effects, clinical outcomes (expectation of cure) and quality of life (Functional Assessment of Chronic Illness Therapy-General). Results: Among the 30 patients enrolled, the median age was 67 years old (range, 44-91); most were male (70%), married (80%), and well-educated (70%). Renal cell carcinoma (70%) was the most common form of cancer. Before starting immunotherapy (T0), patients expected (1) fewer side effects (83%) compared with other types of cancer treatment, (2) great efficacy in preventing tumor progression (90%). and (3) increased survival (90%). Notably, the expectation of cure with immunotherapy treatment had changed over time (T0 = 24% vs T1 = 7%; P = 0.001) and overall quality of life had increased (median at T0 = 90 vs T1 = 98; P = 0.01). Three months into treatment (T1), patients perceived themselves as less active (T0 = 70% vs T1 = 63%; P = 0.02), however just 16% reported severe side effects, including fatigue (10%) and diarrhea (10%). In general, patients were satisfied with the management of these side effects (60%). The majority of patients perceived improvement in their condition (50%) and were satisfied with their treatment (60%). Conclusions: This longitudinal study suggests that inaccurate perceptions of cure with immunotherapy may recede over time, with an increased proportion of patients estimating a more accurate (and lower) chance of cure after 3 months of treatment. Patients also reported improved quality of life despite these adjusted expectations of cure.

Association between TERT promoter mutations and clinical outcome with immune checkpoint inhibitor therapy for advanced urothelial cancer

561

Background: Recently published data suggests that the presence of a TERT promoter mutation is predictive of superior overall survival (OS) in patients (pts) with advanced/metastatic bladder cancer (mUC) treated with an immune checkpoint inhibitor (ICI) (Kouchkovsky et al, JITC 2021). We aim to validate the results of this study in a large independent cohort. Methods: Pts with mUC treated at two tertiary cancer centers with available genomic data collected in the course of routine clinical care were identified retrospectively. Pts that had received at least one line of ICI therapy in the metastatic setting were selected. Demographic and treatment data were collected, with pts divided into two groups based on the presence or absence of TERT mutation status ( TERTm or TERTwt, respectively). We evaluated OS from diagnosis of at least muscle invasive disease, progression free survival (PFS), and objective response rate (ORR) with ICI therapy across the two groups. OS in our cohort was compared with findings from pts with bladder cancer in The Cancer Genome Atlas (TCGA) database. Results: From our combined data sets, a total of 166 pts had available genomic data, with 64 TERTm pts (52:12 M:F) and 58 TERTwt pts (32:26 M:F) meeting criteria for inclusion. Median age at diagnosis was 67 in both groups. The site of primary disease was bladder in 54 (84%) TERTm vs. 41 (71%) in TERTwt; 10 (16%) and 17 (29%) had upper tract disease, respectively. 47 (73%) TERTm pts and 40 (69%) TERTwt pts had pure urothelial disease; 17 (27%) and 18 (31%) pts had mixed/pure variant histology, respectively. 37 (58%) and 42 (72%) pts received first-line ICI therapy whereas 27 (42%) and 16 (28%) received subsequent-line therapy in TERTm and TERTwt, respectively. At the time of analysis, there were 24 (38%) patients alive in TERTm, and 23 (40%) patients alive in TERTwt. OS was 35 vs. 36 mos (95% CI 0.62-1.51, P=0.66) in TERTm and TERTwt, respectively. PFS on ICI therapy was 4.6 vs. 5.3 mos (95% CI 0.58-1.34, P≥0.99) in TERTm and TERTwt, respectively. ORR was 75% in TERTm and 50% in TERTwt (P=.004). OS in the TCGA database was 35 mos in TERTm and 47 in TERTwt (P=0.19) from a total of 311 and 127 pts, respectively. Conclusions: In contrast to previously published data, our data show no difference in OS and PFS on the basis of TERT mutational status in pts with mUC treated with ICI therapy. Further analysis from larger datasets is needed to reconcile the role of TERT mutations within this patient population.

The impact of antibiotic (Ab) exposure on clinical outcomes in patients with metastatic renal cell carcinoma (mRCC) treated with immune checkpoint inhibitors (ICI) or VEGF targeted therapy (VEGF-TT)

4552

Background: Retrospective studies have shown an association between Ab exposure and inferior clinical outcomes in patients receiving ICI across various tumor types, including mRCC. However, it is unclear whether Ab exposure has a unique interaction with ICI or is an independent prognostic marker, regardless of treatment. We sought to examine Ab exposure and its association with clinical outcomes in patients with mRCC treated with ICI compared to VEGF-TT. Methods: We identified patients treated with ICI (anti-PD-L1 alone or in combination with VEGF or CTLA4 inhibitor) or VEGF-TT alone in first to fourth line settings from 2009-2020 across 3 academic centers in North America. Ab exposure was defined as administration of Ab within 60 days prior to initiation of systemic therapy. Outcomes of interest were response rate (RR), time to treatment failure (TTF) and overall survival (OS). Multivariable Cox regression was performed to control for imbalances in International mRCC Database Consortium (IMDC) risk factors, histology, and treatment line. Results: We identified 748 patients. Among the ICI (n=427) and VEGF-TT (n=321) cohorts, 13% vs 15% (p=0.47) had Ab exposure and 57% vs 48% (p=0.046) were treated in the first line setting. The proportion of favorable, intermediate, and poor risk disease by IMDC criteria differed between Ab exposed and unexposed patients in the ICI (14% vs 18%, 47% vs 62%, 39% vs 21% p=0.03) and VEGF-TT (7% vs 13%, 43% vs 60%, 50% vs 27%, p=0.01) cohorts. RR, TTF and OS results are displayed in Table 1. Multivariable analysis did not show a significant independent association between Ab exposure and OS in both the ICI (HR 1.13, p=0.62) and VEGF-TT (HR 1.32, p=0.16) cohorts. Treatment modality (ICI vs VEGF-TT) did not modify the effect of Ab exposure on OS (p=0.84). Conclusions: Ab exposure was associated with higher IMDC risk scores in both the ICI and VEGF-TT cohorts as well as inferior OS on univariable analysis. After adjusting for IMDC risk factors, histology and treatment line, we were unable to find an independent association between Ab exposure and OS in multivariable analysis for either cohort.[Table: see text]

Outcomes of first-line (1L) ipilimumab and nivolumab (IPI-NIVO) and subsequent therapy in metastatic renal cell carcinoma (mRCC): Results from the International mRCC Database Consortium (IMDC)

4554

Background: IPI NIVO is approved for 1L treatment of IMDC intermediate/poor risk mRCC based on the CHECKMATE 214 trial. Herein, we report the clinical effectiveness of 1L IPI NIVO and second line (2L) therapy in the real-world setting. Methods: Using the IMDC dataset, patients (pts) treated with 1L IPI NIVO were identified. The outcomes of interest were 1L and 2L overall response rate (ORR), treatment duration (TD), time to next treatment (TTNT), and overall survival (OS). Results: 706 pts were included: 9% (57/614), 58% (354/614), and 33% (203/614) were IMDC favorable (fav), intermediate (int), and poor risk, respectively. Median age was 61 years. The majority of pts were males (71%), had clear cell histology (85%), and underwent nephrectomy (61%). 36%, 19%, and 8% of patients had bone, liver, and brain metastases, respectively. The 12-month OS for pts with IMDC fav, int, and poor risk disease was 92%, 79%, and 56%, respectively (p<0.01). The corresponding estimates for 24 months were 80%, 69%, and 38% (p<0.01). Pts who responded (39%) were more likely to have better IMDC risk category (p=0.02), received nephrectomy (p=0.04), normal neutrophil count (p<0.01), and clear cell histology (p=0.01). Pts with progressive disease as best response (27%) were more likely to have not received nephrectomy (p<0.01), worse IMDC risk category (p=0.02), bone metastases (p=0.01), liver metastases (p=0.04), and non-clear cell histology (p=0.01). Of the 66% (466/706) of pts who discontinued 1L IPI NIVO, 51% (236/466) received 2L therapy: sunitinib (40%), cabozantinib (25%), pazopanib (18%), axitinib (8%), and others (9%). The ORR, median TD, and median OS for those who received either sunitinib, cabozantinib, pazopanib or axitinib was 16%, 4.5 months (mo) (95% CI 3.7-5.6), and 14.5 mo (95% CI 10.9-25.9), respectively. 33% (129/386) of pts discontinued IPI NIVO due to irAEs. Conclusions: Our study benchmarks the real-world experience of 1L IPI NIVO in mRCC. IMDC criteria is prognostic for clinical outcome. Tyrosine kinase inhibitors have clinical activity post IPI NIVO.[Table: see text]

First results of a randomized phase IB study comparing nivolumab/ipilimumab with or without CBM-588 in patients with metastatic renal cell carcinoma

4513

Background: Recent evidence suggests that the gut microbiome is a potent mediator of immune checkpoint inhibitor (ICI) activity in metastatic renal cell carcinoma (mRCC), with both specific bacterial species and cumulative microbial diversity driving response (Routy et al Science 2018; Salgia et al Eur Urol 2020). We examined whether the butyrate-producing bacterium Clostridium butyricum, the key constituent of CBM-588, could modulate the gut microbiome in patients (pts) with mRCC receiving nivolumab/ipilimumab (N/I) and secondarily improve clinical outcome. Methods: An open-label, randomized study was conducted, with key eligibility criteria including confirmed clear cell and/or sarcomatoid mRCC, intermediate/poor risk by IMDC criteria and no systemic therapy for metastatic disease. Patients were randomized 2:1 to receive either N/I+CBM-588 or N/I alone. N/I was dosed at 3 mg/kg and 1 mg/kg IV every 3 weeks for 12 weeks, followed by N at 480 mg IV every 4 weeks. CBM-588 was dosed orally at 80 mg bid. Stool was collected for bacteriomic profiling at baseline and 12 weeks. Metagenomic sequencing was employed using previously published methods (Dizman et al Cancer Med 2020). The primary endpoint of the study was change in Bifidobacterium spp. from baseline to week 12. Secondary endpoints included change in microbial diversity and clinical outcomes including response rate (RR) and progression-free survival (PFS). Results: 30 pts were randomized between April 2019 and Nov 2020; 1 pt was excluded after genomic sequencing clarified a diagnosis of sarcoma. Among 29 evaluable patients (21:8 M:F), median age was 66, 10 pts (34%) had sarcomatoid features and 24 pts (83%) were intermediate risk. Metagenomic sequencing of paired stool specimens showed an 8-fold increase in B. bifidum and a 6-fold increase in B. adolescentis in pts receiving N/I+CBM-588 from baseline to week 12. C. butyricum was detected only in pts receiving CBM-588. Pathogenic species (e.g., Escherichia. coli and Klebsiella spp.) were more prevalent in pts not receiving CBM-588. RR was significantly higher among pts receiving N/I+CBM-588 vs N/I alone (59% vs 11%; P = 0.024). Median PFS was also prolonged with the addition of CBM-588 to N/I (NR vs 11 weeks; P < 0.001). No significant difference in grade 3/4 toxicities were observed between study arms. Conclusions: This is the first randomized, prospective study to suggest enhancement of ICI response with a live bacterial product. The observed clinical impact is corroborated by biologic findings supporting gut modulation by CBM-588. Clinical trial information: NCT03829111.

Bridging the gaps between tertiary and community care networks: Results from a southern California survey research analysis

1538

Background: Although many tertiary cancer centers offer access to myriad research protocols, the majority of patients nevertheless receive treatment at community practices. We sought to examine the barriers that hamper clinical collaboration between tertiary and community practice environments in Southern California. Methods: A 31-item survey was distributed to community and tertiary oncologists using REDCap, a browser-based electronic data capture system. Survey questions assessed the following attributes: demographics and features of clinical practice, referral patterns, availability and knowledge pertaining to clinical trials, strategies for knowledge acquisition, and integration of community and tertiary practices. Results: The survey was distributed to 98 oncologists, 85 (87%) of whom completed it in full. The most common institutional affiliations were City of Hope Comprehensive Cancer Center (58%), University of California, Los Angeles (10%), and Cedars Sinai Medical Center (8%). In total, 52 (61%) respondents were community practitioners and 33 (38%) were tertiary oncologists. A majority (56%) of community oncologists defined themselves as general oncologists whereas almost all (97%) tertiary oncologists reported a subspecialty. Clinical trial availability was the most common reason for pt referrals to tertiary centers (73%). The most frequent barrier to tertiary referral was financial considerations (59%). Clinical trials were offered by 97% of tertiary practitioners as compared to 67% of community oncologists (p = 0.001). Of note, while a majority of tertiary center providers (52%) described the primary value of community practices to be a source of referrals for clinical trials, most community oncologists (82%) reported only a minimal-to-moderate understanding of clinical trials available at regional tertiary centers. Conclusions: Community oncologists refer patients to tertiary centers primarily with the intent of clinical trial enrollment; however, significant gaps exist in their knowledge of trial availability. Our results identify the need for enhanced communication and collaboration between community and tertiary providers to expand patients’ access to clinical trials.

Evaluation of cabozantinib (cabo) in combination with direct oral anticoagulants (DOAC) or low molecular weight heparin (LMWH) in renal cell carcinoma (RCC)

291

Background: Venous thromboembolism (VTE) is the second leading cause of death in patients with cancer. Despite cabo improving RCC outcomes, VTE management in these patients remains a challenge, partly due to poor understanding of cabo safety profile and drug interactions with anticoagulants. Recent anti-Xa DOAC studies demonstrated comparable efficacy and safety with LMWH for VTE treatment in patients with cancer. Thus far, cabo clinical trials have largely allowed concurrent LMWH use but not DOACs. Herein, we investigated the hemostasis safety profile of cabo with different anticoagulants in patients with RCC. Methods: We performed a retrospective multicenter study (7 sites) of patients with advanced RCC receiving treatment with cabo. Patients were allocated into three groups: cabo with concomitant use (at least 1 week) of 1) DOACs (anti-Xa inhibitors), 2) LMWH, or 3) no anticoagulant. Primary endpoint was to evaluate the rate of major bleeding events (defined per the International Society of Hemostasis and Thrombosis criteria) in the above groups. Secondary endpoint was rate of new/recurrent VTE while on anticoagulation. Overall comparison between groups was analyzed by Fisher exact test. If a difference was found, then pairwise comparison was done. Results: Between 2016-2020, 172 patients with RCC received cabo (DOAC 50, LMWH 18, and no anticoagulant 104). At initiation, cabo median dose was 60 mg but 45% had dose reduction. Median age was 63 [IQR 57-69]. Most were males (77%), had clear cell histology (81.5%), underwent nephrectomy (76.7%), and had intermediate IMDC risk disease (59%). Cabo was first, second, and subsequent line of therapy in 19.8%, 34.9%, and 45.3% of patients, respectively. The table below shows major bleeding and VTE events between groups. An overall difference of major bleeding was found between the three groups comparison ( p=0.009). There was no difference in major bleeding events between patients who received DOAC vs LMWH ( p=0.28) and DOAC vs no anticoagulant ( p=0.1) but there was a difference between LMWH vs no anticoagulant ( p=0.02). Two patients died from bleeding (one in LMWH and one in DOAC group). Conclusions: This study highlights the first reported real world experience of cabo with different anticoagulants in patients with advanced RCC. Cabo use with a DOAC had a similar bleeding risk in comparison to patients not receiving any anticoagulation. In carefully selected patients, DOACs can be considered as concurrent medications in those receiving cabo. Given the low number of patients receiving LMWH, it is difficult to draw conclusions from this group. Data are currently being updated to expand subjects receiving DOAC and LMWH in our cohort. [Table: see text]

First assessment of the stool mycobiome in patients (pts) with metastatic renal cell carcinoma (mRCC) receiving targeted therapy (TT) or immunotherapy (IO)

337

Background: Previous studies have associated specific stool bacterial species with response to both targeted therapy and immunotherapy (Routy et al Science 2018; Dizman et al Cancer Med 2020). Abundant fungal elements also constitute the human microbiome (the so-called “mycobiome”); we explore whether these could be related to clinical benefit (CB) from TT. Methods: Pts from 2 simultaneously conducted studies were included in the analysis. Both studies enrolled patients with histologically confirmed RCC with metastatic disease; in one study, pts received standard of care (SOC) TT, while in the other pts received SOC IO. In both studies, stool was collected at baseline and at multiple timepoints thereafter. Whole metagenome sequencing was performed for fungal microbiome composition (TGen North, AZ). Linear discriminant analysis (LDA) effect size (LEfSe) was used for comparison of the gut mycobiome in patients who obtained clinical benefit (CB; complete response, partial response or stable disease > 6mos) versus no clinical benefit (NCB; progressive disease or stable disease ≤6mos) from TT or IO. Results: A total of 50 samples from 24 pts (19:5 M:F) were included in the analysis. The majority of pts (19; 79%) had clear cell histology. 15 pts received TT while 9 pts received IO. The fungal genera demonstrating the highest abundance was Saccharomyces with a median relative abundance of 86.9% (range, 11%-99%). LEfSe performed in different taxonomic levels revealed Malassezia globosa (LDA = 4.93; P = 0.038) and Alternaria infectoria (LDA 4.94; P = 0.018) as gut mycobiome components associated with NCB, and order Russulales associated with CB from TT (LDA = 4.93; P = 0.018). In contrast, no association was identified between mycobiome profile and CB in the IO-treated group. The presence of several pathogenic fungi such as Candida albicans and Aspergillus fumigatus was noted in a minority of pts and did not have any bearing on clinical outcome. In pts with serial samples, a trend towards decreasing Saccharomyces spp. (the most abundant species) and increasing fungal diversity was noted. Conclusions: Our study is the first to highlight potential associations between the mycobiome and CB with TT. Our finding of Malassezia spp resulting in lack of CB with TT bolsters findings from Aykut et al (Nature 2019), implicating the same genera in progression of pancreatic cancer. Confirmation of these findings in larger series is underway.

Radiomic features of renal cell carcinoma primary and metastatic sites as predictors of TERT and BAP1 mutations

282

Background: TERT and BAP1 mutations are associated with poor clinical outcome in patients (pts) with metastatic renal cell carcinoma (mRCC) (Dizman et al JITC 2020; Joseph et al J Urol 2016). In this study we explore radiogenomics as a non-invasive method to identify these alterations. Methods: Pts with mRCC who had genomic testing in the course of routine clinical care were included in the current analysis. Pts were assessed with the GEM Extra assay, a CAP-accredited, CLIA-certified test encompassing paired tumor-normal whole exome sequencing (WES) and tumor whole transcriptome sequencing (TGen; Phoenix, AZ). Pts underwent CT imaging; radiomic analysis was performed on the segmented metastatic and primary lesions. Features were independently correlated with TERT and BAP1 mutation status to generate Pearson correlation values (PCVs). Results: 92 pts (65:27 M: F) were included in the analysis; of these, the majority of pts (84%) had clear cell histology. Alterations in the TERT gene were seen in 12 pts. In these pts 1,325 radiomic features of the primary tissue were examined and 251 features correlated with a PCV ≥ |0.2|. Of these, 42 features were correlated with a PCV ≥ |0.3|. Highest correlation with TERT mutation was seen with Gray Level Cooccurrence Matrix (GLCM) and First Order Features (FOF). 9 pts had BAP1 mutation with 5 detected in primary tumor and 4 in metastatic sites. Analysis of primary tumor imaging yielded no significant associations between radiomic features and BAP1 mutation. However, out of approximately 1,500 radiomic features noted in metastatic sites, 111 features correlated with BAP1 mutation with a PCV ≥ 0.2. Of these, 15 features correlated with a PCV ≥ 0.3. The radiomic features with the highest correlation with BAP1mt were Gray Level Dependence Matrix (GLDM) and GLCM. Conclusions: By identifying a correlation between radiomic features of TERT mutation in primary tumors and BAP1 mutation in metastatic sites, our work may ultimately yield a non-invasive method of discerning mutational status in patents with mRCC. Efforts are ongoing to validate our findings within The Cancer Imaging Archive.

Distinct cytokines predict response to immunotherapy and targeted therapy in metastatic renal cell carcinoma (mRCC)

352

Background: Previous studies have suggested a link between plasma cytokines and mRCC outcomes with systemic therapy. In a prospective study, we assessed whether plasma cytokines could separately predict outcome with immunotherapy or targeted therapy. Methods: Eligible patients (pts) had histologically proven mRCC with intent to receive a vascular endothelial growth factor-tyrosine kinase inhibitor (VEGF-TKI) or an immune checkpoint inhibitor (ICI). Immunologic profiles were evaluated at several time points using a Human Cytokine 30-plex protein assay (Invitrogen). Clinical benefit (CB) was defined as complete response, partial response, or stable disease ≥ 6 months. Results: A total of 56 pts (40:16 M:F) were enrolled; 23 pts and 33 pts received VEGF-TKI and ICI, respectively. The most common VEGF-TKI was cabozantinib; the most common ICI was nivolumab. CB was similar between VEGF-TKI and ICI arms (65% vs 54%). Pts with CB from VEGF-TKIs had lower pretreatment levels of IL-6 (p = 0.02), IL-1RA (p = 0.03), and G-CSF (p = 0.02). Major shifts in plasma cytokines were seen as early as one month; these data will be presented. Conclusions: Distinct plasma cytokines predict benefit with VEGF-TKIs and ICIs. Ongoing work will incorporate analysis of pts receiving VEGF-TKI and ICI combination therapy.

Fixed-dose Pegfilgrastim is Safe and Allows Neutrophil Recovery in Patients with Non-Hodgkin's Lymphoma

Twenty-nine patients with non-Hodgkin's lymphoma received a single subcutaneous injection of 6 mg pegfilgrastim approximately 24 h after the start of CHOP chemotherapy. The safety of pegfilgrastim in this patient population was determined by reports of adverse events. The pharmacokinetics of pegfilgrastim were characterized and the duration of grade 4 neutropenia, time to absolute neutrophil count (ANC) recovery to > or = 2.0 x 10(9)/l, neutrophil nadir, and incidence of febrile neutropenia were determined in the first 21-day chemotherapy cycle. The incidence of grade 4 neutropenia in cycle 1 was 43% with a mean (SD) duration of grade 4 neutropenia value of 1.0 (1.4) day. No apparent relationship between the duration of grade 4 neutropenia and body weight was observed. The median [quartiles] time to ANC recovery was 10 [9, 11] days. The incidence of febrile neutropenia was 11%. No unexpected adverse events were reported and no patient developed antibodies to pegfilgrastim. Serum concentration of pegfilgrastim reached a maximum (median [quartiles]) of 128 [58, 159] ng/ml at approximately 24 h after administration, and was followed by a second smaller peak (median [quartiles]) of 10.6 [3.0, 20.5] ng/ml at the time of the neutrophil nadir. After the second peak, concentration of pegfilgrastim declined linearly with a median terminal half-life of approximately 42 h.

Capecitabine Plus Paclitaxel As Front-Line Combination Therapy for Metastatic Breast Cancer: A Multicenter Phase II Study

Purpose

The goal of this multicenter, open-label phase II study was the clinical evaluation of combination therapy with the oral fluoropyrimidine capecitabine and the taxane paclitaxel in patients with metastatic breast cancer (MBC).

Patients and Methods

Forty-seven patients with MBC received oral capecitabine at 1,650 mg/m2/d (825 mg/m2 twice daily) on days 1 through 14, and intravenous infusion of paclitaxel at 175 mg/m2 on day 1 of each 21-day treatment cycle. Treatment continued until disease progression, intolerable toxicity, or patient's decision to discontinue. Patients (35 to 76 years old) had a median Karnofsky performance status of 90%. Forty-four patients (94%) received study treatment as first-line therapy for metastatic disease.

Results

Objective responses occurred in 24 (51%) patients; seven (15%) complete responses and 17 (36%) partial responses. Stable disease lasting 180 days or more was observed in nine (19%); the clinical response rate was 70%. Median duration of response was 12.6 months, median time to disease progression was 10.6 months, and median overall survival time was 29.9 months. The most common treatment-related adverse events, regardless of severity, were alopecia, hand-foot syndrome, nausea, and fatigue. Neutropenia (15%), alopecia (13%), and hand-foot syndrome (11%) were the only grade 3 or 4 treatment-related adverse events that occurred in more than 10% of patients.

Conclusion

The combination of capecitabine plus paclitaxel is a highly active and generally well-tolerated regimen for first-line treatment of MBC.

Filgrastim-Mediated Neutrophil Recovery in Patients with Breast Cancer Treated with Docetaxel and Doxorubicin

STUDY OBJECTIVES

To study the impact of filgrastim 5 microg/kg given once/day through absolute neutrophil count (ANC) recovery on the duration of grade 4 neutropenia (ANC < 0.5 x 10(3)/mm3) and time to ANC recovery. Additional objectives were to study the average number of filgrastim injections/cycle required to achieve ANC recovery and differences in outcome by cycle.

DESIGN

Combined analysis of two double-blind, randomized, multicenter trials.

PATIENTS

Two hundred twenty-two patients treated for breast cancer.

MEASUREMENTS AND MAIN RESULTS

All patients but one were evaluable for efficacy end points. Mean +/- SD duration of grade 4 neutropenia was 1.7 +/- 1.3 days in cycle 1; the duration decreased in cycles 2-4 to between 1.0 and 1.2 days. Fifty percent of patients had ANC recovery to 10 x 10(3)/mm3 or greater by day 11 of the cycle, and 90% by day 13, corresponding to 10 and 12 days of filgrastim administration, respectively. Across all cycles, the mean +/- SD number of filgrastim injections/cycle was 10.51 +/- 1.70, with little variation among cycles.

CONCLUSION

When filgrastim is administered as recommended, starting 24 hours after chemotherapy and continuing through an ANC of 10 x 10(3)/mm3 or greater, neutrophil recovery is rapid and predictable. Because the first cycle of chemotherapy has the highest rates of neutropenia and febrile neutropenia, it seems prudent to administer growth factor support preemptively.

A dose- and schedule-finding study of darbepoetin alpha for the treatment of chronic anaemia of cancer

A multicentre study evaluated the efficacy and safety of darbepoetin alpha administered weekly (QW), every 3 weeks (Q3W), and every 4 weeks (Q4W) to anaemic patients with cancer not concurrently receiving chemotherapy or radiotherapy. The QW portion (n=102) was an open-label, sequential, dose-escalation design; cohorts received darbepoetin alpha QW by subcutaneous (s.c.) injection at 0.5, 1.0, 2.25, or 4.5 micro g kg(-1) week(-1) for 12 weeks. The 12-week placebo-controlled, double-blind Q3W (6.75 micro g kg(-1)) and Q4W (6.75 or 10.0 micro g kg(-1)) schedules (n=86), which enrolled different patients, took place after the QW schedule and were followed by a 12-week, open-label phase. Patients were evaluated for change in haemoglobin end points and red blood cell transfusions, serum darbepoetin alpha concentration, and safety. Selected domains of health-related quality of life (HRQOL) were measured. With QW dosing, at least 70% of each cohort had a haemoglobin increase from baseline of > or =2 g dl(-1) or a concentration > or =12 g dl(-1) (haematopoietic response). In the 4.5 micro g kg(-1) QW cohort, all patients achieved a haematopoietic response (100%; 95% confidence interval (CI)=100, 100). In the Q3W and Q4W schedules, all cohorts had at least 60% of patients who achieved a haematopoietic response. Darbepoetin alpha effectively increases haemoglobin concentration when given QW, Q3W, or Q4W. Less-frequent administration may benefit patients with chronic anaemia of cancer and their caregivers alike.

Novel erythropoiesis stimulating protein (NESP) for the treatment of anaemia of chronic disease associated with cancer

Anaemia is a common haematologic disorder in patients with cancer and has a multifactorial aetiology, including the effects of the malignancy itself and residual effects from previous therapy. Novel erythropoiesis stimulating protein (NESP, darbepoetin alfa), a protein with additional sialic acid compared with erythropoietin (EPO), stimulates erythropoiesis by the same mechanism as recombinant human erythropoietin (rHuEPO) but it is biochemically distinct. NESP, with its approximately 3-fold greater serum half-life, can maintain haemoglobin levels as effectively as rHuEPO in anaemic patients with chronic renal failure and do so with less frequent dosing. We investigated the ability of NESP to safely increase haemoglobin levels of anaemic patients with non-myeloid malignancies not receiving chemotherapy. NESP was administered under the supervision of a physician at doses of 0.5, 1.0, 2.25 or 4.5 mcg kg(-1)wk(-1)for a maximum of 12 weeks. This report includes 89 patients completing the study by November 2000. NESP was well tolerated, with no reported dose-limiting toxicities or treatment-related severe adverse events. Increasing doses of NESP corresponded with increased efficacy. The percentage (95% confidence interval) of patients responding ranged from 61% (42%, 77%) in the 1.0 mcg kg(-1)wk(-1)group to 83% (65%, 94%) in the 4.5 mcg kg(-1)wk(-1)group.