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TPS4196 Background: Advanced BTC patients have poor prognosis. Up to 40% of BTCs have KRAS mutations and are associated with worse overall survival (OS). With a median OS of 7.7 months in KRAS wild-type compared to 1.7 months in KRAS mutated disease, these alterations are independent poor prognostic factors in BTC. Gemcitabine and cisplatin (GC) with or without immunotherapy are often used as 1st-line therapies. However, there is a lack of data on best 2nd-line regimens. mFOLFOX6 (5-fluorouracil [5-FU], leucovorin [LV], oxaliplatin) or liposomal irinotecan+5-FU+LV are options when no biomarkers are found (e.g., MSI-H, BRAFV600E, FGFR-fusions, IDH1-mutation, HER2-overexpression). Prior studies do not demonstrate benefit with MEK inhibitors (MEKi), but none of the studies had biomarker selection. Pre-clinical studies in BTC cell lines suggest synergy between MEKi and 5-FU. Thymidylate synthase (TS )levels induced by 5-FU are downregulated by addition of binimetinib. Early clinical studies show safety and tolerance of this combination. In this study, we will evaluate if the combination of mFOLFOX6+binimetinib improves OS for patients with BTC and MAPK mutations compared to mFOLFOX6 alone in 2nd-line therapy. Methods: EAY191-A6 is a treatment study arm of the NCI ComboMATCH master registration trial EAY191. The A6 trial has a randomized phase II design, enrolling a maximum of 66 patients. Patients with any MAPK pathway mutations except those with available therapies will be eligible. Patient must first enroll to the EAY191 master trial. Local molecular results may be used for enrollment. Submission of tissue at baseline is mandatory. Eligible patients will be randomized 1:1 to mFOLFOX6 vs mFOLFOX6 + binimetinib (45 mg oral twice a day every 14 days). Stratification factors include location and stage of disease. Primary efficacy analysis will compare OS in the intent-to-treat population. If the observed hazard ratio (HR) of experimental arm vs standard of care is < 0.545 (corresponding to an observed increase in OS by 5 months or longer), experimental treatment will be considered superior. An interim futility analysis at 50% of expected events will be conducted. If the observed HR is ≥ 1, experimental treatment will not be considered superior, and accrual maybe suspended. Secondary endpoints include progression-free survival, objective response rate, duration of response, disease control rate and toxicity of treatments. Exploratory objectives include prognostic modeling, correlations of genomic alterations with response or resistance and use of machine learning for outcome prediction. This study is active and open to accrual. Clinical trial information: NCT05564403 .

Chronic lymphocytic leukemia (CLL) is characterized by multiple copy number alterations (CNAs) and somatic mutations that are central to disease prognosis, risk stratification, and mechanisms of therapy resistance. Fluorescence in situ hybridization (FISH) panels are widely used in clinical applications as the gold standard for screening prognostic chromosomal abnormalities in CLL. DNA sequencing is an alternative approach to identifying CNAs but is not an established method for clinical CNA screening. We sequenced DNA from 509 individuals with CLL or monoclonal B-cell lymphocytosis (MBL), the precursor to CLL, using a targeted sequencing panel of 59 recurrently mutated genes in CLL and additional amplicons across regions affected by clinically relevant CNAs [i.e., del(17p), del(11q), del(13q), and trisomy 12]. We used the PatternCNV algorithm to call CNA and compared the concordance of calling clinically relevant CNAs by targeted sequencing to that of FISH. We found a high accuracy of calling CNAs via sequencing compared to FISH. With FISH as the gold standard, the specificity of targeted sequencing was >95%, sensitivity was >86%, positive predictive value was >90%, and negative predictive value was >84% across the clinically relevant CNAs. Using targeted sequencing, we were also able to identify other common CLL-associated CNAs, including del(6q), del(14q), and gain 8q, as well as complex karyotype, defined as the presence of 3 or more chromosomal abnormalities, in 26 patients. In a single and cost-effective assay that can be performed on stored DNA samples, targeted sequencing can simultaneously detect CNAs, somatic mutations, and complex karyotypes, which are all important prognostic features in CLL.

Performing 3D ultrasound imaging at a real-time volume rate (e.g., &gt;20 Hz) is a challenging task. While 2D array transducers remain the most practical approach for real-time 3D imaging, the large number of transducer elements (e.g., several thousand) that are necessary to cover an effective 3D field-of-view impose a fundamental constraint on imaging speed. Although solutions such as multiplexing and specialized transducers, including sparse arrays and row-column-addressing arrays, have been developed to address this limitation, they inevitably compromise imaging quality (e.g., SNR, resolution) in favor of speed. Coupled with the high equipment cost of 2D arrays, these compromises hinder the widespread adoption of 3D ultrasound imaging technologies in clinical settings. In this presentation, we introduce an innovative transducer clip-on device comprising a water-immersible, fast-tilting electromechanical acoustic reflector and a redirecting reflector to enable real-time 3D ultrasound imaging using common 1D array transducers. We will first introduce the principles underlying our novel technique, followed by validation studies incorporating simulation and experimental data. We will also demonstrate the feasibility of using the clip-on device to achieve a high 3D imaging volume rate that is suitable for advanced imaging modes such as shear wave elastography, blood flow imaging, and super-resolution ultrasound localization microscopy.

TPS2700 Background: Though immunotherapy with anti-PD-1 immune checkpoint inhibitors (ICIs) has led to improvements in clinical outcomes in patients with cancer, when used as monotherapy in the advanced setting, only 18-25% of patients respond to ICI. Notably, ICI frequently lacks anti-tumor activity in immune-cold cancers where T cell priming is missing. Recent breakthroughs in identifying personal neoantigens via a comprehensive analysis of cancer sequencing data have brought increased attention to neoantigen cancer vaccines. Personalized cancer vaccines targeting neoantigens have shown early promise. While neoantigens have recently been investigated in some cancer types, the current neoantigen prediction algorithms have often focused on the MHC class-I subtype, single nucleotide mutations (SNM), small insertions and deletions (INDEL). We recently developed an informatics workflow, REAL-neo, for the identification, quality control (QC), and prioritization of both class-I and class-II human leukocyte antigen (HLA) bound neoantigens that arise from somatic SNM, INDEL, aberrant RNA splicing, and gene fusions, generating much more potent neoantigen candidates. Furthermore, we demonstrated robust T-cell response and prolonged survival by combining ICI and cancer vaccines in preclinical models. This single-arm phase I clinical trial is in progress to assess the safety, feasibility, and immunogenicity of personalized neoantigen vaccines in combination with pembrolizumab in patients with advanced solid cancers. Methods: The vaccine consists of up to 20 peptides (15-30 mer) comprising patient-specific neoantigens identified from tumor DNA and mRNA sequencing data using REAL-neo and delivered with GM-CSF as an adjuvant. The first cohort of three patients will be treated at dose level 1 consisting of 4 or 5 peptides at 300 mcg/peptide and GM-CSF 125 mcg per injection site in each of four limbs. After Cohort 1 is deemed safe, the study will expand to cohort 2, when patients will be enrolled at the same dose level for vaccine plus Pembrolizumab 200 mg i.v. Neoantigen vaccine will be given via subcutaneous injection on days 1, 4, 8, 15, and 21 (cohorts 1 and 2) and weeks 5 and 8 (booster dose for cohort 2 only). Cohort 1 has been completed without dose-limiting toxicity (DLT). Enrollment in Cohort 2 began in January 2024. AEs are assessed according to CTCAE v5. and safety findings are reviewed by data safety medical board (DSMB). Key eligibility criteria include 1) histologically confirmed locally advanced or metastatic solid malignancies and 2) cancer progression after at least one line of the standard-of-care (SOC) systemic treatment. For cohort 2, patients must be eligible to receive pembrolizumab per SOC or the treating physician’s judgment. Clinical trial information: NCT05269381 .

Abstract Objective The aim of this study is to assess whether clinical and imaging characteristics are associated with the hormonal subtype, growth, and adrenalectomy for incidental adrenal cortical adenomas (ACAs). Design This is a single-center cohort study. Methods Consecutive adult patients with incidental ACA were diagnosed between 2000 and 2016. Results Of the 1516 patients with incidental ACA (median age 59 years, 62% women), 699 (46%) had nonfunctioning adenomas (NFAs), 482 (31%) had mild autonomous cortisol secretion (MACS), 62 (4%) had primary aldosteronism (PA), 39 (3%) had Cushing syndrome, 18 (1%) had PA and MACS, and 226 (15%) had incomplete work-up. Age, sex, tumor size, and tumor laterality, but not unenhanced computed tomography Hounsfield units (HU), were associated with hormonal subtypes. In a multivariable analysis, ≥1 cm growth was associated with younger age (odds ratio [OR] = 0.8 per 5-year increase, P = .0047) and longer imaging follow-up (OR = 1.2 per year, P &lt; .0001). Adrenalectomy was performed in 355 (23%) patients, including 38% of MACS and 15% of NFA. Adrenalectomy for NFA and MACS was more common in younger patients (OR = 0.79 per 5-year increase, P = .002), larger initial tumor size (OR = 2.3 per 1 cm increase, P &lt; .0001), ≥1 cm growth (OR = 15.3, P &lt; .0001), and higher postdexamethasone cortisol (OR = 6.6 for &gt;5 vs &lt;1.8 μg/dL, P = .002). Conclusions Age, sex, tumor size, and laterality were associated with ACA hormonal subtype and can guide diagnosis and management. Tumor growth was more common with younger age and longer follow-up. Unenhanced HU did not predict hormonal subtype or growth. Adrenalectomy for MACS and NFA was mainly performed in younger patients with larger tumor size, growth, and elevated postdexamethasone cortisol.

ObjectivesThere have been significant advances in the management of large (≥20 mm) laterally spreading tumors (LSTs) or nonpedunculated colorectal polyps; however, there is a lack of clear consensus on the management of these lesions with significant geographic variability especially between Eastern and Western paradigms. We aimed to provide an international consensus to better guide management and attempt to homogenize practices.MethodsTwo experts in interventional endoscopy spearheaded an evidence‐based Delphi study on behalf of the World Endoscopy Organization Colorectal Cancer Screening Committee. A steering committee comprising six members devised 51 statements, and 43 experts from 18 countries on six continents participated in a three‐round voting process. The Grading of Recommendations, Assessment, Development and Evaluations tool was used to assess evidence quality and recommendation strength. Consensus was defined as ≥80% agreement (strongly agree or agree) on a 5‐point Likert scale.ResultsForty‐two statements reached consensus after three rounds of voting. Recommendations included: three statements on training and competency; 10 statements on preresection evaluation, including optical diagnosis, classification, and staging of LSTs; 14 statements on endoscopic resection indications and technique, including statements on en bloc and piecemeal resection decision‐making; seven statements on postresection evaluation; and eight statements on postresection care.ConclusionsAn international expert consensus based on the current available evidence has been developed to guide the evaluation, resection, and follow‐up of LSTs. This may provide guiding principles for the global management of these lesions and standardize current practices.

3588 Background: The brain-gut axis, a bidirectional network between the central and enteric nervous systems, plays a critical role in modulating the gastrointestinal tract function. Increasing evidence suggests that neuronal signaling molecules can promote gastrointestinal cancers; however, the mechanisms remain unclear. Gamma-aminobutyric acid (GABA) is a major inhibitory neurotransmitter and dysregulated GABA signaling has been found in CRC, affecting both tumor and tumor microenvironment. Here, we investigated the association between tumor GABA pathway gene expression and first-line treatment outcomes in mCRC. Methods: We evaluated the impact of the expression of 25 genes in the GABA pathway ( GABBR1, GABBR2, GABRA1, GABRA2, GABRA4, GABRA5, GABRA6, GABRB1, GABRB3, GABRD, GABRE, GABRG1, GABRG2, GABRG3, GABRQ, GABRR1, GABRR2, ABAT, ALDH5A1, GAD1, GAD2, SLC6A1, SLC6A13, SLC6A11, SLC6A12) on treatment outcomes (overall survival: OS; progression free survival: PFS) of 433 pts enrolled in the randomized, phase III CALGB/SWOG 80405 trial. RNA extracted from FFPE tumor samples was sequenced using the HiSeq 2500 (Illumina). The associations between gene expression (continuous, per standard deviation increase) and outcomes were assessed via the multivariable Cox proportional framework, with hazard ratios (HR) and 95% confidence intervals (CI) computed. The likelihood ratio test was used for interaction tests. False discovery rate (FDR) was controlled at 5% with the Benjamini-Hochberg method. Results: Overall, low GAD1 (encoding for glutamate decarboxylase 1, the enzyme responsible for catalyzing the production of GABA from L-glutamic acid) was associated with longer PFS (HR: 1.26, 95% CI [1.13, 1.41], P = 3.2E-05) and OS (HR 1.27 [1.13, 1.43], P = 5.9E-05) across all treatment arms. High ABAT (encoding for the aminotransferase responsible for GABA catabolism) was also associated with longer OS (HR 0.81 [0.72, 0.91], P = 6E-04). To evaluate the predictive value, interactions with targeted therapies bevacizumab (n = 226) vs cetuximab (n = 207) were tested. We found significant interactions for PFS with ABAT ( P= 0.0017) and OS with SLC6A13 ( P= 0.0014 ).In pts treated with cetuximab, high ABAT expression was significantly associated with longer PFS (HR 0.73 [0.61, 0.87], P = 2.8E-04), and high SLC6A13 was marginally associated with worse OS (HR 1.18 [1.00, 1.39], P = 0.052). We did not observe similar associations in pts treated with bevacizumab. Conclusions: Our results highlight a potential role for GABA signaling in affecting mCRC treatment outcomes, suggesting that GABA pathway genes may be promising novel predictive and prognostic biomarkers and supporting the rationale to investigate GABA as a target for drug development. ClinicalTrials.gov Identifier: NCT00265850

4032 Background: RATIONALE-306 (NCT03783442) is the first global study to investigate anti-programmed cell death protein 1 therapy in combination with different chemotherapy (chemo) options in the first-line (1L) treatment of advanced/metastatic esophageal squamous cell carcinoma (ESCC). At interim analysis (IA), tislelizumab (TIS) plus chemo demonstrated a statistically significant, clinically meaningful improvement in overall survival (OS) versus placebo (PBO) plus chemo, with a manageable safety profile. Here, we report updated efficacy and safety data with minimum 3 years’ follow-up after study unblinding at IA. Methods: Adults with unresectable locally advanced recurrent/metastatic ESCC and no prior systemic treatment for advanced disease were enrolled and randomized (1:1; stratified by region, prior definitive therapy, and investigator [INV]-chosen chemo) to receive TIS 200 mg (Arm A) or PBO (Arm B) IV every 3 weeks plus chemo (platinum plus fluoropyrimidine or platinum plus paclitaxel), until disease progression or intolerable toxicity. The primary endpoint was OS in the intent-to-treat population. Secondary endpoints included progression-free survival (PFS), objective response rate (ORR), and duration of response (DoR), all per INV, and safety. Results: In total, 649 patients (pts) were randomized (Arm A, n=326; Arm B, n=323). At a minimum study follow-up of 36.0 months, improvements in OS, PFS, and DoR in Arm A versus B (Table) were maintained relative to the IA. The hazard ratio (HR) for OS with TIS plus chemo versus PBO plus chemo was 0.70 (95% confidence interval: 0.59, 0.83). Similar to the IA, incidences of any-grade (96.6% vs 96.3%) or grade ≥3 (67.0% vs 64.5%) treatment-related adverse events (TRAEs) were comparable between Arms A and B, respectively; treatment-emergent adverse events leading to treatment discontinuation were higher in Arm A (32.1%) versus B (22.1%). In Arm A versus B, respectively, serious TRAEs occurred in 29.9% vs 19.6% of pts; TRAEs leading to death occurred in 1.9% and 1.2%. Conclusions: After minimum 3 years’ follow-up, 1L TIS plus chemo continued to demonstrate clinically meaningful improvements in OS and PFS and durable antitumor response benefit versus PBO plus chemo in pts with advanced/metastatic ESCC, with no new safety signals. Clinical trial information: NCT03783442 . [Table: see text]

3144 Background: Longitudinal brain structure changes across the lifespan are associated with neurodegenerative disorders. We previously showed that genetic variants in dopamine and Parkinson’s disease genes are predictive and prognostic in mCRC. Indeed, the brain-gut axis is emerging as a critical player in CRC biology. Hence, we investigated whether the tumor gene expression of 3 metabolic genes involved in brain development and aging could affect treatment response in patients enrolled in the CALGB/SWOG 80405 trial. Methods: 433 mCRC pts treated with either bevacizumab (bev, n = 226) or cetuximab (cet, n = 207) in combination with first-line chemotherapy were included in the analysis. RNA was isolated from FFPE tumor samples and sequenced on the HiSeq 2500 (Illumina). Overall survival (OS) and progression-free survival (PFS) were compared between groups of pts categorized by tertiles of expression of 3 genes: APOE, DACH1, and GPR139. Likelihood ratio tests, hazard ratios and 95% confidence intervals were computed from multivariate Cox proportional hazards models, adjusting for age, sex, ethnicity, ECOG PS, tumor location, number of metastatic sites, KRAS, MSI status, and treatment. Logrank P-values describe differences without adjustment for patient characteristics. Results: Both APOE and DACH1 (but not GPR139) met the 0.05 false discovery rate threshold for association with both PFS ( P = .00085, P = .015) and OS ( P = .021, P = .021, respectively) in the full Cox models. In cet-treated pts, APOE-high (H) showed significantly shorter PFS (median 9.2 vs 11.8 vs 13.0 months (mo), high vs low (as reference) logrank P = .0021) and OS (median 21.9 vs 35.8 vs 34.6 mo; logrank P = .0017) compared to APOE-median and -low, respectively. Opposite results were observed for DACH1, where DACH1-H tumors had longer PFS (median 14.5 vs 10.6 vs 8.07 mo; logrank P = .0011) and OS (median 39.4 vs 30.9 vs 21.5 mo; logrank P = .0021) when treated with cet. In bev-treated pts, similar results were observed with APOE-H showing shorter OS (median 25.8 vs 26.3 vs 37.5 mo; logrank P = .0016) and DACH1-H longer OS (median 36.5 vs 28.3 vs 22.4 mo; logrank P = .0017). No significant gene-treatment interaction was observed for either gene for PFS and OS. Conclusions: The tumor expression of metabolic genes associated with changes in the brain structure was prognostic in mCRC pts treated with first-line therapy. Notably, APOE and DACH1 have been recently reported to play a role in CRC where APOE overexpression has been associated with aggressive biological behavior whereas DACH1 has been shown to suppress CRC cell growth and invasion. Our results support this evidence and suggest that further investigation into the role of APOE and DACH1 in CRC biology and into their potential as targets for drug development is warranted. Trial Identifier: NCT00265850.

11562 Background: High-grade soft tissue sarcomas (STS) pose a therapeutic challenge due to the high risk of recurrence, even following complete resection. Anlotinib is a multi-targeted tyrosine kinase inhibitor blocking angiogenesis pathways of VEGFR, FGFR, and PDGFR. Given a promising efficacy for treating patients with unresectable advanced STS in previous trials, we evaluated the role of anlotinib as adjuvant therapy for completely resected high-grade STS. Methods: In a single-center, double-blinded, randomized, controlled trial, eligible patients were those adults who had not received adjuvant chemotherapy regimens after complete resection of high-grade STS. Patients were randomly assigned in a 1:1 ratio to receive either oral 12 mg anlotinib or placebo once daily on days 1-14 every 3 weeks as a cycle, with up to six cycles until disease recurrence, unmanageable toxicity or death. The primary endpoints included 1-year, 2-year disease-free survival (DFS). Results: Between June 2019 and November 2023, 88 patients were randomly assigned to receive anlotinib (n=44) or placebo (n=44). With a median follow-up of 25.99 months at data accrual cutoff on Jan 15, 2024, the 1-year and 2-year DFS rates were 88% and 77% in the anlotinib group, compared to 64% and 58% in the placebo group. Compared to patients in the placebo group, patients in the anlotinib group had a reduced risk of disease recurrence (HR 0.47 [95% CI 0.22~1.00, P= 0.0445]). The median DFS was not reached. Based on tumor histology, the greatest improvement in DFS with anlotinib versus placebo was observed in patients with myxofibrosarcoma (1-year DFS rate: 82% versus 61%; 2-year DFS rate: 64% versus 43%, HR 0.54 [95% CI 0.17~1.65], P= 0.2698) and undifferentiated pleomorphic sarcoma (1-year DFS rate: 86% versus 67%; 2-year DFS rate: 78% versus 67%, HR 0.58 [95% CI 0.12~2.87], P= 0.4971). Thirty-eight patients experienced adverse events (AEs; 34 with grade 1~2, 4 with grade 3): 28 patients (64%) in the anlotinib group versus 10 patients (23%) in the placebo group ( P<0.001). Three patients discontinued anlotinib, including two for proteinuria/hematuresis (2/44, 5%) and one for secondary poor surgical wound healing (1/44, 2%). Conclusions: Current results suggest anlotinib could lower disease recurrence risk in patients with completely resected high-grade STS, with an acceptable toxicity profile. Clinical trial information: NCT03951571 . [Table: see text]