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6549 Background: Representation and outcomes of women, older adults, and racial minorities in ICI trials has not been previously described. Methods: MEDLINE and Embase were searched to identify ICI RCTs. Data for trial characteristics, proportion of trials reporting race, age and sex as well as the proportion of patients by race, age and sex enrolled in ICI trials was collected. Descriptive statistics were reported for trials reporting minority representation and proportion of included patients by race, age and sex. Disparities in representation were calculated using enrollment incidence disparity (EID) and enrollment incidence ratios (EIR) by comparing trial enrollment against U.S. population-based estimates acquired from the SEER 18 incidence database. The relationship of EID to key trial characteristics were compared using standard parametric and non-parametric statistical tests. Trends in EIR were analyzed using the Joinpoint Regression Analysis software. Results: 108 ICI trials from 2009 to 2020 with 48,360 patients were included in this analysis. All RCTs reported sex (101/101). 78 trials reported race (72%), of which only 41 trials (38%) reported data on all 5 U.S. racial categories (Black, White, Asian, Pacific Islander and Native American). Participation of Black patients was reported in 66 trials (61%), White participants in 78 trials (72%), Asians in 69 trials (64%), Native Americans and Pacific Islanders in 41 trials (38%), and Hispanics in 24 trials (22%). Age categories were inconsistently defined, and 80 trials (74%) reported the proportion of patient by age categories. Subgroup analyses of clinical outcomes by race, age and sex were reported in 17 (22%), 62 (79%) and 57 (73%) trials respectively. Women (trial proportion [TP]: 32%; EIR: 0.77), patients aged ≥ 65 years (TP: 42%; EIR: 0.74), Black participants (TP: 1.8%; EIR: 0.17) and Hispanic participants (TP: 5.9%; EIR: 0.67) were largely underrepresented, and Asians were overrepresented (TP: 15.9%; EIR: 2.64). Black patients were underrepresented across all cancer types. Similarly, women, older adults ( > 65 years of age) and Hispanic patients were consistently underrepresented across cancer types with few exceptions. Representation of older adults increased significantly from 2010-2020 (APC: 2.72), while representation of Black patients decreased significantly from 2009-2020 (APC: -23.37). Black patients were found to be significantly underrepresented in phase III trials (p = 0.0005), trials with OS as the primary endpoint (p = 0.004), and PD1 inhibitor trials (p = 0.002). Hispanics were significantly underrepresented in PD1 inhibitor trials (p = 0.003). Conclusions: There is both suboptimal reporting about participation and underrepresentation of women, racial minorities (particularly Black patients) and older adults in ICI trials as compared to their cancer incidence.

4541 Background: Radical cystectomy (RC) is the standard of care for patients with BCG-unresponsive high risk non-muscle invasive bladder cancer (NMIBC), but many patients are unfit for surgery or elect bladder preservation. This trial was designed to evaluate the activity of atezolizumab in BCG-unresponsive high risk NMIBC. Methods: This single arm phase II registration trial testing systemic atezolizumab (1200 mg IV) every 3 weeks for one year aimed to enroll 135 (70 CIS and 65 non-CIS) eligible patients with histologically proven BCG-unresponsive high risk NMIBC who were unfit for or declined RC. Here we report the 18 month results for all eligible patients who received at least one protocol treatment. The co-primary endpoints were pathological complete response (CR) rate at 6 months in patients with CIS (reported at ASCO 2020), and event-free survival (EFS) in all patients at 18 months using Kaplan-Meier methods (KM), conditional on a positive CIS response rate. A sample size of 135 evaluable patients provided 93% statistical power for detecting a 30% 18-month EFS rate versus 20% using a one-sided alpha = 0.05. EFS in the subset with Ta/T1 disease and duration of response in CIS patients were secondary endpoints. Results: 172 patients were enrolled, 166 received at least one dose of atezolizumab and are included in the safety analysis, and, of those, 128 were eligible and included in the efficacy analysis. As previously reported, 20 (27%) out of 74 patients with CIS attained a pathologic CR at 6 months. The KM estimate of 12 month (actual 11.9 mo) duration of response after 6 month CR for CIS patients was 54% (95% CI 30%, 78%) and the median duration of response was 16.5 months. The KM EFS rate at 18 months in 74 patients with CIS was 17% (90% CI 9%, 25%). The 18 month KM EFS rate in the overall population of 128 patients with Ta, T1 and CIS was 29% (90% CI 22%, 36%). The 18 month actuarial EFS rate in 54 patients with Ta/T1 disease was 45% (90% CI 34, 57%). Any possibly or probably treatment-related adverse event (TRAE) was observed in 142 out of 166 (86%) patients who received any atezolizumab regardless of eligibilty. The most frequent TRAEs were fatigue 72 (43%), diarrhea 34 (20%), and anemia 38 (23%). Grade 3-5 TRAEs occurred in 28 (17%) patients, including rash in 4 (2%), hyponatremia in 4 (2%), hypertension in 3 (2%) and elevated liver function tests in 3 (2%). There were two treatment-related deaths (sepsis and respiratory failure due to myasthenia gravis). Conclusions: The observed response of atezolizumab at 6 and 18 months in patients with BCG-unresponsive CIS suggests that this could be a valuable treatment to address a critical unmet need in this patient population. The 18 month EFS in patients with Ta/T1 disease suggests activity in this patient subset. This trial provided no new safety concerns. Funding: NIH/NCI grants: CA180888, CA180819, CA180820, CA180821, CA180863 and in part by Genentech. Clinical trial information: NCT02844816.

TPS3161 Background: The p53 pathway has been implicated in antitumor immunity, including antigen presentation and T-cell proliferation. Loss of p53 function can increase resistance to immunotherapy across many tumor types. Eprenetapopt (eprenet) is a small molecule that stabilizes the folded structure of p53, resulting in activation of mutant p53 and stabilization of wild-type (WT) p53. It also targets the cellular redox homeostasis, resulting in induction of apoptosis in tumor cells. In vivo, mice carrying supernumerary copies of the TP53 gene harbor a pro-inflammatory tumor microenvironment, an effect recapitulated in TP53 normal-copy mice treated with eprenetapopt. Combining eprenetapopt and anti-PD1 or anti-CTLA4 therapy resulted in enhanced tumor growth inhibition and improved survival in TP53 WT mice inoculated with B16 melanoma and MC38 colon adenocarcinoma cells . Based on these results, we hypothesized that eprenet-induced p53 stabilization may augment response to immunotherapy. To test this hypothesis, we are conducting a phase 1b/2 study of eprenet in combination with pembrolizumab (eprenet+pembro) in pts with solid tumors. Methods: The primary objectives are to determine the maximum tolerated dose (MTD) and recommended phase 2 dose (RP2D) and to assess the safety and tolerability of eprenet+pembro in pts with advanced solid tumors. The secondary objectives are to estimate the anti-tumor activity and to describe the pharmacokinetics of the combination. Exploratory objectives include assessing predictive and pharmacodynamic markers of response. The study includes a safety lead-in with a 3+3 dose de-escalation design for pts with advanced solid tumors with known tumor TP53 mutation status ( TP53 WT is acceptable) (max 18 pts), followed by expansion cohorts in pts with NSCLC, gastric/GEJ and urothelial cancer (max 100 pts). In expansion, pts with urothelial and gastric cancers must be naïve to anti-PD-1/ L1 therapy. Eprenet is given IV once daily on Days 1–4 while pembro is administered on Day 3 of each 21-day cycle. The RP2D of eprenet+pembro is considered the dose at which ≤ 1 of 6 pts in a cohort has a dose-limiting toxicity (DLT). Primary endpoints are occurrence of DLTs, adverse events (AEs) and serious AEs with eprenet+pembro. Key secondary endpoints are best objective response, progression free survival and overall survival. Exploratory endpoints include gene mutations by next generation sequencing (including TP53), mRNA expression, multiplex immunohistochemistry and transcriptomics, multiplex flow cytometry on peripheral blood mononuclear cells and cytokines in serum. Continuous monitoring of toxicity will be conducted. The trial opened in May 2020 and is actively enrolling patients. Clinical trial information: NCT04383938.

Objectives To evaluate outcomes of patients achieving a post‐treatment pathological stage of <ypT2N0 at radical cystectomy (RC) following neoadjuvant chemotherapy (NAC) for muscle‐invasive bladder cancer (MIBC) to identify an optimal definition of pathological response. Patients and Methods Patients from 10 international centres who underwent NAC for cT2–4aN0–1 MIBC and achieved <ypT2N0 disease at RC were included. The primary outcome was time to recurrence, either local or distant. Kaplan–Meier and Cox proportional hazards regression were used to evaluate associations between clinicopathological variables and outcomes. Results A total of 625 patients were included. The median age was 66 years and 80% were male. Gemcitabine and cisplatin (GC, 56%) and methotrexate, vinblastine, doxorubicin and cisplatin (MVAC)/dose‐dense (dd)MVAC (32%) were the most common NAC regimens. ypT0, pure ypTis, ypTa ±ypTis and ypT1 ± ypTis were attained in 58.1%, 20.0%, 7.6% and 14.2% of patients, respectively. The cumulative incidence of recurrence at 5 years was 9%, 16%, 29% and 30%, respectively. Pathological stage was prognostic for recurrence, with ypTa ± Tis (hazard ratio [HR] 3.20, 95% confidence interval [CI] 1.40–7.30) and ypT1 ± Tis disease (HR 4.03, 95% CI 2.13–7.63) associated with a significantly higher recurrence risk. Pure ypTis (HR 1.66, 95% CI 0.82–3.38) and the type of NAC regimen (ddMVAC: HR 1.59, 95% CI 0.55–4.56; MVAC: HR 1.18, 9%% CI 0.25–5.54; reference: GC) were not associated with recurrence. Conclusion We propose that optimal pathological response after NAC be defined as attainment of ypT0N0/ypTisN0 at RC. Patients with ypTaN0 or ypT1N0 disease (with or without Tis) at RC displayed a significantly higher risk of recurrence and may be candidates for trials investigating adjuvant therapy.

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

335 Background: Systematic reviews are outdated quickly when the evidence is rapidly evolving as the process is laborious and there is little incentive for primary author team of an index SRMA to update the evidence. Consequently, there is an epidemic of redundant SRMAs performed by different teams—sometimes with conflicted results—for treatment of first line mRCC. Methods: We have created a living, interactive systematic review (LISR)and network meta-analysis(LINMA) for the treatment of first line mRCC using an Artificial intelligence (AI) assisted framework for evidence synthesis (Living, Interactive evidence synthesis framework) (LIvE) . The framework is implemented in five-layered architecture (application layer, shared module layer, core service layer, middleware layer, and storage layer) which work together to automate the identification of new studies and analysis and semi-automate the screening and data extraction. Dynamic features such as interactive tables, figures and evidence maps are enabled using Python and JavaScript programming languages. Results: We have maintained a living, interactive evidence profile for the first line treatment mRCC since September 2019 ( LIVING WEBSITE) . Living search strategy identifies new studies as they become available. As of October 13, 2020 LISR, includes data 14 clinical trials ( PRISMA ). Baseline characteristics are summarized in an interactive table ( TABLE) . Cabozantinib& Nivolumab (Cabo-Nivo) is the highest ranked drug for improving Overall Response (OR), Progression Free Survival (PFS) and Overall Survival (OS) whereas Ipilimumab in combination with Nivolumab (Ipi-Nivo) is highest ranked drug for achieving complete response (CR). Ipi-Nivo and Atezolizumab & Bevacizumab (Ate-Bev) ranked highest and Cabo-Nivo ranked lowest for treatment related Adverse events (TRAEs). Results of network meta-analysis are summarized as interactive tables and plots ( NMA ), summary of findings tables ( MULTIPLE COMAPRISONS ) and evidence maps ( MAP ). Conclusions: LISRs can potentially reduce redundancy, increase transparency, reproducibility, enable shared-decision making (at a guideline level, or in a patient-clinician dyad) and support living guidelines.

e24114 Background: Pharmacogenomics (PGx) testing is used increasingly in cancer supportive care for drug and dose selection, and side effects prediction with antidepressants, antiemetics, and pain medications. Genetic variants in genes that encode for drug metabolizing enzymes (CYPs), transporters (SLC6A4) and drug receptors (HTR2A, OPRM1, etc) are well known for these medications. They contribute to inter-individual differences in medication safety and efficacy. We report on their frequency and effect on supportive care drugs in patients with solid tumors. Methods: Between 06/06/19 and 12/18/19, solid tumor cancer patients at Mayo Clinic Arizona were enrolled in a PGx prospective study. They were genotyped using a multi-gene panel, OneOme RightMed. The panel assessed 27 genes, including CYP2C9, CYP2C19, CYP2D6, CYP3A4, COMT, OPRM1, GRIK4, HTR2A, SLC6A4, associated with pain medications, antidepressants, and antiemetics. PGx pharmacist provided medication recommendations and dose adjustments based on PGx test results and concurrent medications. Results: 200 patients were swabbed and 196 patients were genotyped. The results were available within 5 days. All patients were also assessed for pheno-conversion (drug-drug-gene interactions) by a pharmacist. Recommendations were made based on predicted phenotype. Various solid tumor types were represented, including prostate (19.9%), colorectal (17.9%), melanoma (14.8%), and others (47.4%). Median age was 65 with 59.2% patients being male and 40.85% female. All had at least one actionable polymorphism related to these medications. The most significant findings were related to CYP2C19 and CYP2D6 genes. Of 196 patients, a total of 132 (67.3%) had other than normal CYP2D6 metabolizer phenotype and 112 (57.1%) had other than normal CYP2C19 metabolizer phenotype. Based on these genotypes, alternatives to pain medications were recommended for 37 patients, to ondansetron in 9 patients, and to anti-depressants in 51 patients. Conclusions: Genetic variants were commonly found that affect supportive care medications used in oncology practice and contribute to inter-individual differences associated with increased risk of adverse drug effects and reduced efficacy. PGx guided recommendation may help physicians in individualizing medication treatment outcomes for patients with different cancer types and with polypharmacy. PGx trained pharmacist can serve as a valuable asset in optimizing personalized medication management.

10029 Background: This is the first randomized trial testing the addition of an oncolytic virus to an immune checkpoint inhibitor for advanced melanoma. At the 3-year (yr) follow-up, the combination (combo) of T-VEC and ipi demonstrated durable and statistically superior objective response rate (ORR) over ipi alone (36.7% vs. 16.0%; odds ratio, 3.0; 95% Cl, 1.6–6.0; P = 0.002). Complete response (CR) rate was 21.4% with the combo and 6.0% with ipi. Median overall survival (OS) was not reached in either arm. In this post hoc analysis, we utilized the 3-yr landmark data to explore the relationship between CR and OS in the combo arm. Methods: Pts with unresectable, stage IIIB-IV melanoma were randomized 1:1 to receive combo or ipi alone. T-VEC was administered intratumorally on day 1 of week (wk) 1 at 106 plaque-forming units (PFU)/mL followed by subsequent doses at 108 PFU/mL on day 1 of wk 4, and every 2 wks thereafter. Ipi (3 mg/kg) was given every 3 wks starting on day 1 of wk 6 for up to 4 doses. Response was assessed by investigators per immune-related response criteria every 12 wks until disease progression. The primary endpoint was ORR; key secondary endpoints were OS, progression-free survival, and safety. Results: 198 pts were randomized (98 to combo; 100 to ipi). As of February 25, 2019, the median follow-up time was 40.0 mos (range: 0.2–63.7) for the combo arm. Among 98 pts who received combo, 21 (21.4%) had a best overall response of CR including 8 who converted from an initial partial response (PR), 15 (15.3%) had PR, 19 (19.4%) had stable disease, 30 (30.6%) had progressive disease, and 13 (13.2%) were unevaluable. Of 21 pts achieving CR, 17 (81%) had ECOG status of 0, 16 (76.2%) had stage IIIB-IVM1a disease, and 16 (76.2%) had no visceral metastases. Median duration of CR was not reached (range: 5.4[+]–58.2[+] mos); 19 of 21 CRs lasted more than 6 months. The baseline tumor burden was lower in pts with CR than in those with non-CR. Median OS was not reached in pts with CR (range: 25.1[+]–63.7[+] mos) and was 47.6 mos (range: 0.2[+]– 63.7[+] mos) in pts with non-CR (Log-rank P = 0.0005). The Kaplan–Meier estimated 3-year OS rate was 100.0% for patients with CR and 52.3% for those with non-CR. Conclusions: CR rate was higher with T-VEC plus ipi than with ipi alone in pts with advanced melanoma (21.4% vs. 6.0%). In the combo arm, CR was associated with prolonged OS, and pts with CR tended to have better ECOG performance status, earlier-stage disease, and lower baseline tumor burden, as compared with those with non-CR. Clinical trial information: NCT01740297.

e17587 Background: Radium (Ra)-223 has become the cornerstone treatment in patients with metastatic castrate-resistant prostate cancer (mCRPC) with bone metastases. Ra-223 has been shown to suppress abnormal bone formation by inducing DNA double-strand breaks in tumor cells. This can reduce skeletal-related events, as well as improve survival and quality of life. Studies have indicated mutations that regulate DNA damage response in prostate cancer as susceptible to PARP inhibitors and platinum-based therapies. This study aims to evaluate mCRPC response to Ra-223 stratified by tumor genomics. Methods: This is a retrospective study of mCRPC patients who received Ra-223 and genetic testing within the Mayo Clinic database (Arizona, Florida, and Minnesota). Patient demographics, genetic mutations, treatment responses in terms of alkaline phosphatase (ALP) and prostate-specific antigen (PSA), and survival were assessed. Primary end points were progression-free survival (PFS) and overall survival (OS) from time of first radium treatment. Results: 239 mCRPC patients treated with Ra-223 were identified. Germline and/or somatic genetic sequencing was available in 50 patients, who had a median age of 61 years at time of diagnosis and 68 years at time of Ra-223 treatment. Median Gleason score at time of diagnosis was 8.0. 100% of patients received prior androgen deprivation therapy. 72% received prior docetaxel, and 18% received prior cabazitaxel. Notable mutations included TP53 (45.2%), TMPRSS2-ERG (28.6%), PTEN (26.2%), BRCA1/2 (14.3%), ATM (9.3%), CDK12 (7.1%), and Rb (4.9%). TMPRSS2-ERG was the second most commonly found mutation, with median OS 12.7 mo versus 15.4 mo in patients without TMPRSS2-ERG mutations (p = 0.099). In patients with CDK12 mutations (2 of 28 tested positive), PFS was 10.4 mo versus 5.6 mo in patients without CDK12 mutations (p = 0.157). The assessment of ALP and PSA response to radium treatment stratified by genetic mutation did not reach statistical significance. Conclusions: Among mCRPC patients treated with Ra-223 at Mayo Clinic, TMPRSS2-ERG was the second most commonly found genetic mutation and had observed worse survival outcomes that approached statistical significance. Prospective studies and increased sample sizes are needed to determine the impact of genetic mutations in response to Ra-223.