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Importance Semaglutide, a glucagonlike peptide-1 receptor agonist (GLP-1RA), has recently been implicated in cases of nonarteritic anterior ischemic optic neuropathy (NAION), raising safety concerns in the treatment of type 2 diabetes (T2D). Objective To investigate the potential association between semaglutide and NAION in the Observational Health Data Sciences and Informatics (OHDSI) network. Design, Setting, and Participants This was a retrospective study across 14 databases (6 administrative claims and 8 electronic health records). Included were adults with T2D taking semaglutide, other GLP-1RA (dulaglutide, exenatide), or non–GLP-1RA medications (empagliflozin, sitagliptin, glipizide) from December 1, 2017, to December 31, 2023. The incidence proportion and rate of NAION were calculated. Association between semaglutide and NAION was assessed using 2 approaches: an active-comparator cohort design comparing new users of semaglutide with those taking other GLP-1RAs and non–GLP-1RA drugs, and a self-controlled case-series (SCCS) analysis to compare individuals’ risks during exposure and nonexposure periods for each drug. The cohort design used propensity score–adjusted Cox proportional hazards models to estimate hazard ratios (HRs). The SCCS used conditional Poisson regression models to estimate incidence rate ratios (IRRs). Network-wide HR and IRR estimates were generated using a random-effects meta-analysis model. Exposures GLP-1RA and non–GLP-1RAs. Main Outcomes and Measures NAION under 2 alternative definitions based on diagnosis codes: one more inclusive and sensitive, the other more restrictive and specific. Results The study included 37.1 million individuals with T2D, including 810 390 new semaglutide users. Of the 43 620 new users of semaglutide in the Optum’s deidentified Clinformatics Data Mart Database, 24 473 (56%) were aged 50 to 69 years, and 26 699 (61%) were female. The incidence rate of NAION was 14.5 per 100 000 person-years among semaglutide users. The HR for NAION among new users of semaglutide was not different compared with that of the non–GLP-1RAs using the sensitive NAION definition—empagliflozin (HR, 1.44; 95% CI, 0.78-2.68; P = .12), sitagliptin (HR, 1.30; 95% CI, 0.56-3.01; P = .27), and glipizide (HR, 1.23; 95% CI, 0.66-2.28; P = .25). The risk was higher only compared with patients taking empagliflozin (HR, 2.27; 95% CI, 1.16-4.46; P = .02) using the specific definition. SCCS analysis of semaglutide exposure showed an increased risk of NAION (meta-analysis IRR, 1.32; 95% CI, 1.14-1.54; P < .001). Conclusions and Relevance Results of this study suggest a modest increase in the risk of NAION among individuals with T2D associated with semaglutide use, smaller than that previously reported, and warranting further investigation into the clinical implications of this association.

247 Background: Approximately 10% to 15% of men with metastatic castration-resistant prostate cancer (mCRPC) harbor germline mutations. Circulating tumor-derived DNA (ctDNA) as non-invasive approach to characterizing somatic alterations. In this study, we report longitudinal ctDNA assessments in mCRPC patients who have undergone germline testing. Methods: A total of 238 patients, who had undergone both germline testing and ctDNA assessment from Tulane Cancer Center were included in this study. Germline testing was conducted using a multi-gene cancer panel from Invitae, covering 50-86 genes, while somatic alterations in ctDNA were tested through Guardant 360, including 70-83 genes. Somatic alterations with <0.1%, synonymous, and variants of unknown significance were excluded from analyses. Statistical analyses were performed using Pearson Chi-Square Test or Fisher Exact Test. Results: From 2015-2024, 17.2% (41/238) had pathogenic or likely-pathogenic (P/LP) germline mutations. The most common pathogenic germline mutations were in BRCA2 (17.1%; 7/41), BRCA1 (9.8%; 4/41), and CHEK2 (9.8%; 4/41). In ctDNA, germline positive patients were more likely to have frameshift mutations (OR= 1.75, 95% C.I. [1.09, 2.81], p=0.02) and less likely to have copy number amplifications (OR= 0.58, 95% C.I. [0.36, 0.93], p= 0.03) compared to germline negative patients. Among mCRPC patients with germline HRR P/LP mutations, frameshift alterations were significantly more frequent (OR=5.03, 95% CI [2.03, 13.23], p-value=0.0008). mCRPC patients with germline P/LP mutations were more likely to have somatic mutations in BRCA2 (OR=2.85; 95% CI: [1.62, 4.93]; p=0.0002) and GATA3 (OR=3.37, 95% CI: [1.26, 8.51]; p=0.016) detected ctDNA and less likely to have EGFR alterations (mutations and/or amplifications) (OR=0.46; 95%CI: [0.25, 0.80]; p=0.0094). BRCA2 somatic mutations are also more likely to be detected in patients with germline P/LP mutations in HRR genes (OR=0.11, 95% CI [0.03, 0.33], p=0.00004). Conclusions: mCRPC patients with pathogenic germline mutations are more likely to have frameshift and less likely to have copy number amplifications compared to germline negative mCRPC patients. Frameshift mutations are more likely to be detected in patients with germline P/LP in HRR genes. Patients with germline P/LP mutations are more likely to have somatic mutations BRCA2 and GATA3 and less likely to have mutations and/or amplifications in EGFR.

245 Background: Circulating tumor DNA (ctDNA) can be used as a prognostic biomarker in mCRPC patients, with changes in ctDNA providing insight into patient survival. In this study, we evaluate the ctDNA landscape of patients with mCRPC prior to their death. Methods: A retrospective clinical data review, 2015-2024, was conducted at Tulane Cancer Center to identify mCRPC patients who underwent ctDNA testing prior to death. All ctDNA data were obtained through a multi-gene cancer panel via the Guardant 360 assay (70-83 genes). Lethal mCRPC was defined as patients who underwent ctDNA testing ≤3 months prior to death. A matched control group (CTRL) was defined as mCRPC patients with ctDNA collection ≥2 years prior to death or most recent follow-up. Statistical analyses were performed using Pearson Chi-Square Test or Fisher Exact Test whenever appropriate. Furthermore, survival analysis was conducted using the Kaplan-Meier method. Results: There were 70 patients in lethal mCRPC group and 157 patients in CTRL group. Compared to the CTRL group, in lethal mCRPC, somatic mutations and/or amplifications in BRAF(OR=2.1549, 95% C.I. [1.1136,4.1523], p=0.0298), CCND2 (OR=3.7925, 95% C.I.[1.1937,13.3380], p=0.03326), MYC (OR=2.6332, 95%C.I. [1.4158, 4.9120], p=0.0029), PDGFRA (OR=2.5235, 95% C.I. [1.1438, 5.5793], p=0.0291), and PIK3CA (OR=2.0328, 95% C.I. [1.1098, 3.7166], p=0.02846) were significantly more frequent. Additionally, lethal mCRPC patients were more likely to have missense (OR=4.3194, 95% C.I. [1.443456,19.3338], p=0.01687) and nonsense (OR=1.9364, 95% C.I. [1.06091,3.5250], p=0.04112) mutations at the end-of-life. Patients with a higher allelic fraction (≥0.6%) of TP53 alterations had a shorter median survival (p-value= 0.034). Conclusions: ctDNA mutations and/or amplifications in BRAF, CCND2, MYC, PDGFRA, and PIK3CA were more frequently detected in lethal mCRPC compared to matched CTRLs. Additionally, mCRPC patients with a lethal phenotype were more likely to have missense and nonsense mutations compared to the CTRL group. CtDNA assessment of copy number alterations was limited to amplifications only; additionally, with this assay, distinguishing between gene level and large scale chromosomal amplification is not assessable. Though this study is limited to a single-institution with retrospective analyses of clinical testing, understanding the somatic landscape of lethal mCRPC is critical for development of new biomarkers, strategies and ultimately druggable targets.

TPS272 Background: Prostate-specific membrane antigen (PSMA)-targeting positron emission tomography (PET) radiopharmaceuticals enable early detection of metastatic and recurrent prostate cancer (PCa). High urinary radioactivity of some PSMA-PET agents can affect interpretation of scans in the pelvic region (prostate/prostate bed [PB]; pelvic lymph nodes [PLN]). 18 F-Piflufolastat and 18 F-flotufolastat are FDA-approved, mainly renally cleared, diagnostic PSMA-PET agents; data suggest 18 F-flotufolastat has lower urinary radioactivity than 18 F-piflufolastat, but no clinical differences have been confirmed by head-to-head intra-patient studies. The present study will directly compare the urinary radioactivity of 18 F-piflufolastat with 18 F-flotufolastat in men with low prostate-specific antigen (PSA) biochemical recurrence (BCR) of PCa after radical prostatectomy (RP). Methods: This multicenter, prospective, intra-patient comparator study will include men (≥ 18 years old) with low PSA (≤ 0.5 ng/mL) BCR of PCa who have had RP ≥ 6 months before enrollment (with undetectable PSA post surgery) and are due to have routine 18 F-piflufolastat PET. Men who have had prior 18 F-piflufolastat PET or salvage therapy, or with conditions affecting urinary output, will be excluded. Eligible patients will undergo 18 F-piflufolastat PET followed by 18 F-flotufolastat PET ≥ 24 hours but ≤ 10 days later. No diuretic will be administered for scanning purposes. Each radiopharmaceutical will be administered as a single intravenous bolus per approved US prescribing information (USPI). Scanning (with the same scanner for both scans) will start 50–90 minutes post injection of 18 F-piflufolastat and 50–70 minutes post injection of 18 F-flotufolastat. Each patient will be their own control. The primary endpoint will be difference in mean standardized uptake value (SUV mean ) between 18 F-piflufolastat and 18 F-flotufolastat as assessed in volumes of interest drawn on the urinary bladder. Secondary endpoints for both agents will include detection rates: at the patient level (overall; by baseline PSA); for local recurrences in PB subregions; and for PLN lesions. For secondary endpoints, PET scans will be interpreted per product-specific USPI by 2 specially trained, blinded, central readers (a third reader will adjudicate disagreements). Safety will be monitored until 24 hours after the second scan. Around 60 men will be screened and ≥ 52 with evaluable PET scans for both agents will be included in the primary analysis. The primary endpoint will be assessed for normality and a difference in SUV mean will be tested using 2-sided paired tests (Wilcoxon signed-rank test [non-normal]; t-test [normal]). All further endpoints, including safety, will be summarized descriptively. The trial has been open for enrollment since 10/24. Clinical trial information: NCT06604442 .

686 Background: Blue-light cystoscopy (BLC) is an established procedure for use in the diagnosis and surveillance of patients with non-muscle-invasive bladder cancer (NMIBC). It is associated with improved detection rates compared to white light cystoscopy (WLC); however, limited data is available regarding its role in upstaging and/or upgrading when used alongside WLC. The aim of this study is to assess the incidence and features of patients undergoing upstaging and/or risk-group migration with the implementation of BLC. Methods: Using data from the prospective multi-institutional Cysview Registry (2014-2024), patients with NMIBC who underwent transurethral resection or biopsy of bladder tumors were identified. The patients in whom malignant lesions were exclusively detected by BLC, as well as those experiencing an upward change in risk category (as defined by the American Urological Association [AUA] classification) based on BLC findings, were documented. The clinical features of these patients were subsequently reviewed. Results: In this study, 2,854 patients were enrolled, who collectively underwent 4,158 resections and provided 6,432 separate pathology samples. A total of 201 (7%) patients had at least one malignant lesion detected exclusively by BLC while having negative WLC. These lesions (total 335) included carcinoma in-situ (CIS) in 145 (43%), low-grade Ta in 53 (16%), high-grade Ta in 95 (28%), high-grade T1 in 37 (11%), and high-grade T2 in 5 (1%). In patients with multifocal disease, BLC resulted in AUA risk-group upward migration in 66 (2.3%) patients.Theclinical features of these two groups are presented in the table. Taken together, the total rate of upgrading or upstaging using BLC was 9.3%, including migration to low-risk in 1.2%, intermediate-risk in 2.1%, and high-risk in 6%. Conclusions: Using BLC during transurethral resection or biopsy of bladder tumors results in risk group migration in over 9% of patients with NMIBC. This impacts patient management, including the administration of intravesical therapy when it was not initially planned, an extension in the duration of therapy, or the decision to proceed with radical cystectomy. Clinical features of patients with malignant lesions detected by BLC only (A) and those with risk group migration (B). Clinical features A B Age, median (IQR), year 71 (63-76) 71 (61-77) Gender, n (%) Male Female 140 (74)49 (26) 54 (82)12 (18) History of smoking, n (%) 117 (62) 40 (61) Primary occurrence, n (%) 65 (34) 14 (21) History on intravesical therapy, n (%) 92 (49) 40 (61) Urine cytology * , n (%) Positive Suspicious Atypical Negative/NA 33 (17)21 (10)41 (20)106 (53) 13 (20)7 (11)10 (15)36 (54) IQR: interquartile range; NA: not available. *Detected by either voided urine or bladder wash.

537 Background: Translocation renal cell carcinoma (tRCC) is a rare renal cell carcinoma subtype found in about 1-4% of adult patients with RCC and 40% of pediatric RCC cases. Management of advanced tRCC has been guided by clear cell RCC therapy and retrospective reviews which include tRCC cohorts. Novel therapeutic strategies are needed to improve outcomes. This study assessed an individualized neoantigen vaccine with nivolumab plus cabozantinib in a patient with metastatic TFE3-tRCC. Methods: Patient was consented (IRB# 20-011945) for a single-patient investigational new drug (IND#27755). In-house neoantigen prediction bioinformatics pipeline (REAL-neo v2.0) was performed to identify and prioritize neoantigen candidates. Patient underwent lymphodepletion with cyclophosphamide followed by vaccine administration on days 1, 4, 8, 11, 20, 40, week 12, and week 20. Patient was also treated with concurrent nivolumab 480 mg every 4 weeks and cabozantinib 40 mg daily. Objective response rate (ORR) and progression-free survival (PFS) were measured. Results: Patient was diagnosed with TFE3-tRCC and underwent nephrectomy prior to developing metastatic disease. He was treated with multiple liver surgeries, ablations, and radiation therapy without systemic therapy. This controlled his disease for 7 years before he required systemic therapy with ipilimumab plus nivolumab. After 4 cycles, imaging showed progression and was started on cabozantinib which controlled his disease for 1 year. Patient was consented for the neoantigen vaccine. Cycle 1 was administered in April 2022. Three liver lesions and 1 periportal lymph node were monitored. After 4 months of therapy, imaging showed partial response with 34% decrease in sum of target lesions. In June 2023, partial response was ongoing with a 57.4% decrease. A 2 nd vaccine series was administered in June 2023 and had stable disease until progression in June 2024 when patient held his cabozantinib for at least 4 weeks. Neoantigen combination therapy achieved a progression-free survival of 26 months and was well tolerated without significant vaccine-related adverse events. Conclusions: Individualized neoantigen vaccine plus nivolumab and cabozantinib achieved a durable partial response with prolonged progression-free survival. A randomized clinical trial is warranted to further evaluate the efficacy of this combination therapy.

524 Background: Antiangiogenic tyrosine kinase inhibitors (TKIs) play a key role in treating renal cell carcinoma and other solid organ malignancies, but TKIs cause bothersome side effects that frequently necessitate dose reductions or treatment holds. Olanzapine has been useful for palliating symptoms from classical chemotherapies and advanced cancer, but its effect on TKI-related symptoms is largely unknown. This retrospective study aimed to estimate the efficacy of olanzapine for TKI-induced nausea, vomiting, anorexia, weight loss, and insomnia. Methods: All patients prescribed olanzapine with lenvatinib, cabozantinib, axitinib, or tivozanib at Mayo Clinic between January 1, 2018, and June 30, 2024 were assessed for inclusion. For baseline symptom assessment, clinical care team notes documenting the presence or absence of symptoms and indication(s) for starting olanzapine were reviewed. For response assessment, clinical notes and patient portal messages from the first three months after starting olanzapine were evaluated for qualitative descriptions of change in symptom burden. Relevant data were extracted as direct quotations, which were reviewed by the research team and categorized as “improved,” “worsened,” “stable,” or “missing data.” Each symptom domain was analyzed independently when olanzapine was prescribed for multiple interrelated symptoms. Results: A total of 60 patients who received olanzapine for the treatment of TKI-related adverse effects were included. The most common documented indication for olanzapine was nausea without vomiting (n=35), followed by anorexia (n=25), nausea with vomiting (n=16), weight loss (n=16), and insomnia (n=11). In 32 cases (53%), olanzapine was prescribed for multiple, simultaneous symptoms. Response rates for each symptom domain are shown in the table. In addition, prior to olanzapine, 34 patients (57%) had documented weight loss. Following olanzapine, 50% (n=17) gained weight (median increase: 6.1 kg; range: 2.0 - 10.7 kg), 26% (n=9) stabilized their weight (±1 kg), and 24% (n=8) continued to lose weight. Clinicians utilized a TKI dose reduction within one week of olanzapine initiation in 5 cases (8.3%), and 3 of these patients could resume the higher dose of TKI after starting olanzapine. Only 4 patients (7%) discontinued olanzapine within 3 months due to perceived side effects. Conclusions: Olanzapine appears to be effective in treating TKI-induced nausea, vomiting, anorexia, insomnia, and weight loss. Prospective randomized placebo-controlled studies are needed to confirm these findings. Improvedn (%) Worsened n (%) Stablen (%) Missing Datan (%) Nausea without emesis 32 (84) 3 (8) 1 (3) 2 (5) Nausea with emesis 13 (93) 0 (0) 0 (0) 1 (7) Anorexia 26 (74) 2 (6) 4 (11) 3 (9) Insomnia 11 (85) 0 (0) 2 (15) 0 (0)

387 Background: Level 1 evidence supports treatment of high-risk and node positive PCa using 4-9 weeks of radiotherapy (RT) combined with 18-36 months of androgen deprivation therapy (ADT) with or without abiraterone acetate plus prednisone (AAP). While effective, some cancers recur, and this prolonged treatment is associated with inconvenience and variable morbidity. We aimed to determine whether the biological synergy of stereotactic body radiotherapy (SBRT) with a 6-month combination of ADT, AAP, and the PARP inhibitor niraparib, could enable a shorter intensified, yet safe and effective, therapeutic alternative. Methods: ASCLEPIuS (NCT04194554) is a multicenter investigator-initiated phase I/II trial in high-risk or node positive, homologous recombination unselected, PCa. Patients received 6 months of ADT, AAP, niraparib and SBRT to the prostate (37.5-40 Gy) +/- pelvic lymph nodes (25 Gy). Focal prostate/nodal boosting was permitted. The phase I primary endpoint was the maximum tolerated dose (MTD) of niraparib using the time-to-event continuous reassessment method (3 dose levels: 100 mg and 200 mg held during SBRT, or 200 mg concurrent with SBRT). Dose limiting toxicities (DLT) were any persistent grade 4+ hematologic toxicity or any grade 3+ rectal/urinary toxicity at least possibly related to treatment as assessed by CTCAE v5.0. Patient reported quality of life (QOL) was assessed with the EPIC-26 short form. Linear mixed models were used to compare scores over time. Results: Accrual began in Nov. 2020 with a transition from phase I to phase II in May 2023 after enrolling 54 men. Median follow-up of the phase I cohort is 12.1 months (IQR 9.4-18.9), 80% (n=43) had Grade Group 4-5, median PSA was 17 ng/mL (range, 1-73), 15% (n=8) had cN+ disease, and 76% (n=41) received nodal RT. There were 0 DLTs to date, no grade 3+ rectal or urinary toxicities, and 5 serious adverse events at least possibly attributable to study treatment (anemia, non-rectal gastrointestinal, syncope, infection, musculoskeletal). The most common grade 3 toxicities were hypertension (n = 11, 21%) and leukopenia (n=6, 11%). Transient dose reductions or holds of AAP or niraparib occurred in 10 and 11 patients, respectively. There were no statistically significant declines in patient reported urinary QOL at 6- or 12-months post-treatment compared to baseline (all p >0.15). A transient decline in bowel QOL at 6-months occurred (p<0.01), which improved by 12-months (p=0.16). Conclusions: Our phase I findings support the short-term safety and tolerability of the combination of SBRT to the prostate and nodes, ADT, AAP, and niraparib at an MTD of 200 mg in men with high-risk or node positive PCa. Our trial completed phase II enrollment in May 2024, and longer-term safety, efficacy, and genomic correlations will be presented in the future. Clinical trial information: NCT04194554 .

371 Background: Prostate cancer is the most common malignancy in men globally and remains among the top five leading causes of cancer-related deaths. Emerging evidence suggests that early identification of symptoms can detect localized disease thus enabling opportunities for curative intent treatments. This study evaluates the use of the AI-powered prediction model, C the Signs, to passively screen for prostate cancer by leveraging data from electronic medical records (EMRs), offering a novel pathway for identifying high-risk individuals. Methods: A retrospective analysis was conducted using the Mayo Data Platform, encompassing 418,477 male patient records, of which 16,835 were diagnosed with prostate cancer. C the Signs identified patients at risk based solely on their EMR data, utilizing AI-driven pattern recognition. Sensitivity and specificity analyses were performed to assess the prediction model’s accuracy. Additionally, we examined the time-to-diagnosis advantage for patients flagged by the model compared to traditional physician clinical diagnoses. Results: C the Signs demonstrated a sensitivity of 83.3% and a specificity of 52.5% for identifying patients at risk of prostate cancer. Notably, 31.8% of prostate cancer cases were identified at risk up to five years earlier by the model compared to traditional physician clinical diagnosis. Conclusions: The integration of AI-driven prediction models like C the Signs into prostate cancer screening pathways provides an opportunity to enhance early detection, particularly in symptomatic individuals. Compared to prostate-specific antigen (PSA) testing, the model achieved equivalent sensitivity and 38% higher specificity, positioning it as a valuable companion tool for improving patient outcomes.