Shroff, Rachna T.

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 .

4107 Background: Aberrant Wnt/β-catenin activation has been implicated in tumor formation and progression in BTC. CTNNB1 is a key transcriptional co-activator in Wnt signaling. The impact of CTNNB1 alterations on outcomes in intrahepatic (IHCC) vs extrahepatic (EHCC) vs gallbladder (GB) tumors and patterns of gene co-expression is unclear. We examined the molecular correlates and predictive and prognostic significance of CTNNB1 expression in a real-world cohort of pts with BTC. Methods: 7450 BTC tumors were analyzed using Next Generation Sequencing (NextSeq), Whole Exome and Whole Transcriptome Sequencing (NovaSeq) at Caris Life Sciences (Phoenix, AZ). Top quartile transcripts per million (TPM) expression was considered high expressors (Q4), bottom quartile was considered low expressors (Q1) within each subtype. Real-world overall survival (OS) data was obtained from insurance claims. Hazard ratio (HR) was calculated using Cox proportional hazards model, P values were calculated using log-rank test. Significance was determined to be p <0.05. Chi-square and Mann-Whitney tests determined molecular differences between subgroups and adjusted for multiple comparisons (q<0.05). Results: The cohort was comprised of 61% IHCC, 14% EHCC, 23% GB, 2% NOS. CTNNB1 mutations are rare in BTC (1.3%). Pts with CTNNB1-wt tumors had significantly better OS vs CTNNB1-mt (13.6 vs 10.2 mo, HR 0.74, p=0.008). This association remained significant in IHCC (13.2 vs 4.5 mo, HR 0.64, p=0.031) but not EHCC (18.0 vs 11.8 mo, HR 0.87, p=0.64) or GB (12.9 vs 11.0 mo, HR 0.75, p=0.071). CTNNB1-mt tumors were more frequently TP53-mt (63% vs 41%), ERBB2-mt (9% vs 2%) and ATM-mt (9% vs 3%). CTNNB1-wt tumors were more likely BAP-mt (9% vs 0%) and IDH1-mt (10% vs 0%) (all q<0.05). CTNNB1-mt tumors had higher median CTNNB1 expression vs wt (154.9 vs 113.4, q<0.009). Pts with CTNNB1 Q1 expression had significantly better OS vs Q4 (14.5 vs 12.4 mo, HR 0.88, p=0.007). This association held in IHCC (15.0 vs 10.6 mo, HR 0.77, p<0.00001) but not EHCC (17.5 vs 19.9 mo, HR 1.05, p=0.70) or GB (12.4 vs 12.8 mo, HR 1.05, p=0.63). CTNNB1 Q4 expressing tumors were more likely to be TP53-mt (55% vs 34%), PIK3CA-mt (9% vs 5%), KRAS-mt (23% vs 12%) and less likely IDH1-mt (4% vs 14%) compared to Q1 (all q<0.05). CTNNB1 Q4 pts had higher ARID1A, CTLA4, LAG3, HIF1A, TGFB1/2/3, EPHB4, EPHA2, VEGFA expression (FC: 2.1-4.2, all q<0.05) and higher T-cell inflamed score vs Q1. There was a trend towards improved OS in pts with IHCC CTNNB1 Q1 tumors receiving gemcitabine or fluorouracil (17.5 vs 15.0 mo, HR 0.86, p=0.064); no difference in outcomes by CTNNB1 expression in pts receiving immunotherapy. Conclusions: CTNNB1 mutations and mRNA expression levels impact survival in BTC, especially IHCC, and may be associated with benefit from chemotherapy. CTNBB1 alterations are associated with immunogenic, DNA repair and angiogenic pathways and may help identify novel therapeutic strategies for BTC.

4106 Background: The WNT/beta catenin (CTNNB1) pathway plays an integral role in the development of HCC. CTNNB1 has been implicated in HCC progression, metastasis, and drug resistance. We examined associations between CTNNB1 mutations and mRNA expression and clinical outcomes in a real-world cohort of patients with HCC. Methods: 1652 HCC tumors were tested at Caris Life Sciences (Phoenix, AZ) and analyzed with Whole Transcriptome Sequencing (WTS; Illumina Novaseq), Whole Exome Sequencing (NovaSeq,WES) and NextGen DNA sequencing (NextSeq, 592 genes). mRNA expression (transcripts per million) was further stratified into top (Q4) and bottom quartiles (Q1). Kaplan Meier estimates were calculated for overall survival (OS) in the molecularly defined cohorts and estimated from time of tissue collection to last contact. Significance was determined to be p <0.05. Chi-square and Mann-Whitney tests determined molecular differences between subgroups and adjusted for multiple comparisons (q<0.05). Results: Pathogenic CTNNB1 mutations were present in 32% of HCC and mutation status was not associated with CTNNB1 expression level. Pts whose tumors had lower CTNNB1 expression had significantly improved OS, 17.9 vs 12.4 months, Q1 vs Q4, HR 0.72, CI: 0.58-0.89 p=0.002. This association remained significant in patients who received first-line IO (Q1 vs Q4: OS 16.7 vs 10.6 mo, HR 0.54, CI: 0.32-0.94, p=0.025) or TKI (Q1 vs Q4: OS 27.1 vs 17.6 mo, HR 0.60, CI: 0.38-0.94, p=0.025). Low CTNNB1-expressing tumors (Q1) had more frequent ARID1A mutations (15% vs 8%); less frequent TP53 mutations (31% vs 42%); lower VEGFA, EPHB4, EPHA2, HIF1A, TGFB1/2/3 expression, lower MAPK activation and lower T-cell inflamed scores vs Q4 tumors (all q < 0.05). All tumors were MSS. CTNNB1 mutation status (MT vs WT) did not impact survival (OS 17.6 vs 15.3 mo, CTNNB1-MT vs CTNNB1-WT, HR 1.05, CI: 0.91-1.20, p=0.55). Similarly, CTNNB1 mutation status (MT vs WT) did not impact OS in pts treated with IO (19.8 vs 19.6 mo, HR 0.99, p=0.94) or TKI (23.0 vs 22.0 mo, HR 0.86, p=0.33). Conclusions: CTNNB1 mRNA expression, but not CTNNB1 mutation status, is associated with survival in HCC. Patients whose tumors had lower CTNNB1 expression appeared to derive more benefit from immune checkpoint inhibitors and TKI therapy in first line. CTNNB1 expression is associated with DNA repair, immune, neuronal and angiogenic pathways which may pave the way for potential therapeutic opportunities. Further studies are needed to prospectively evaluate CTNNB1 as a biomarker for treatment selection in HCC.

LBA490 Background: Biliary tract cancers (BTCs) are a heterogeneous group of malignancies with a dismal prognosis. Gemcitabine-based regimens are the standard of care in advanced disease, but median overall survival (OS) is roughly 12 months. The addition of albumin-bound paclitaxel to gemcitabine and cisplatin (GAP) demonstrated promising efficacy in a 60 patient, single-arm phase II study (Shroff et al, JAMA Oncol 2019), with observed median OS of 19.2 months. Methods: SWOG 1815 is a randomized, open-label, phase III trial comparing GAP to gemcitabine/cisplatin (GC). The study included newly diagnosed advanced BTC patients (pts), randomized 2:1 to GAP vs. GC. GAP included gemcitabine at 800 mg/m2, cisplatin at 25 mg/m2 and albumin-bound paclitaxel at 100 mg/m2 on days 1 and 8 of a 21-day cycle. GC included standard dosing of gemcitabine at 1000 mg/m2 and cisplatin at 25 mg/m2 on days 1 and 8 of a 21-day cycle. Pts were treated until progression. The primary endpoint was overall survival (OS) with a target hazard ratio of 0.7 with 90% power and a 1-sided alpha of 0.025; randomization was stratified by disease site (intrahepatic cholangiocarcinoma [CCA] vs gallbladder adenocarcinoma [GBC] vs extrahepatic CCA), disease stage (locally advanced vs metastatic), and Zubrod PS 0 vs 1. Results: Of 441 eligible pts randomized, 55% were female. 67% of patients had intrahepatic CCA, 16% had GBC and 17% had extrahepatic CCA. Most pts had metastases (73%). Median OS with GAP vs. GC was 14 vs. 12.7 mo respectively (HR 0.93, 95% CI 0.74-1.19, p=0.58), ORR (confirmed and unconfirmed) 34% vs 25% (p=0.11) and median PFS 8.2 vs 6.4 mo (HR 0.92, 95% CI 0.72-1.16, p=0.47), respectively. Grade 3 and 4 treatment related adverse events (TRAEs) in ≥10% of pts for GAP and GC were anemia, neutropenia, and thrombocytopenia. GAP had more ≥ grade 3 hematologic AEs compared to the GC arm (60% vs. 45%, p=0.003). Discontinuation due to toxicity was at 24% vs 19% (p=0.26) with GAP vs GC. In exploratory subset analyses, GAP vs GC improved OS in pts with locally advanced disease (medians 19.2 vs 13.7 mo; HR 0.67, 95% CI 0.42-1.06, p=0.09) and in GBC pts (medians 17.0 vs 9.3 mo; HR 0.74, 95% CI 0.41-1.35, p=0.33). ORR for GAP vs GC in GBC was 50% vs 24% (p=0.09) and for locally advanced disease 28 vs 21% p=0.74. Conclusions: SWOG 1815 did not result in a statistically significant improvement in median OS with GAP vs. GC. The GAP regimen had higher rates of TRAEs without a statistically significant difference in discontinuation rates. Pts with locally advanced disease and GBC may benefit from the use of GAP. Further analyses are ongoing to understand potential benefit of GAP in subsets of BTC pts. Funding: NIH/National Cancer Institute grants CA180888, CA180819, CA180820, CA180821, and CA180868; and in part by Celgene Corporation, Summit, NJ (subsidiary of Bristol Myer Squibb). Clinical trial information: NCT#03768414 .

PURPOSE Increased awareness of the distinct tumor biology for adolescents and young adults (AYAs) with cancer has led to improvement in outcomes for this population. However, in cholangiocarcinoma (CCA), a paucity of data exist on the AYA population. To our knowledge, we present the largest study to date on AYA disease biology, treatment patterns, and survival outcomes in CCA. METHODS A multi-institutional cohort of patients with CCA diagnosed with intrahepatic cholangiocarcinoma (ICC) or extrahepatic cholangiocarcinoma (ECC) was used for analysis. Retrospective chart review was conducted on patients who were 50 years old and younger (young; n = 124) and older than 50 years (older; n = 723). RESULTS Among 1,039 patients screened, 847 patients met eligibility (72% ICC, 28% ECC). Young patients had a larger median tumor size at resection compared with older patients (4.2 v 3.6 cm; P = .048), more commonly had N1 disease (65% v 43%; P = .040), and were more likely to receive adjuvant therapy (odds ratio, 4.0; 95% CI, 1.64 to 9.74). Tumors of young patients were more likely to harbor an FGFR2 fusion, BRAF mutation, or ATM mutation ( P < .05 for each). Young patients were more likely to receive palliative systemic therapy (96% v 69%; P < .001), targeted therapy (23% v 8%; P < .001), and treatment on a clinical trial (31% v 19%; P = .004). Among patients who presented with advanced disease, young patients had a higher median overall survival compared with their older counterparts (17.7 v 13.5 months; 95% CI, 12.6 to 22.6 v 11.4 to 14.8; P = .049). CONCLUSION Young patients with CCA had more advanced disease at resection, more commonly received both adjuvant and palliative therapies, and demonstrated improved survival compared with older patients. Given the low clinical trial enrollment and poor outcomes among some AYA cancer populations, data to the contrary in CCA are highly encouraging.

Abstract Background: Isocitrate dehydrogenase 1/2 (IDH1/2) is mutated in a subset of cholangiocarcinoma (CCA), gliomas, and other solid tumors. LY3410738 is a potent, selective, covalent, dual inhibitor of IDH1/2 mutations (IDH1/2m). LY3410738 binds covalently at a novel binding site, enabling continued potency in preclinical models in the setting of second site IDH resistance mutations. We present initial results from the first-in-human phase 1 study of oral LY3410738 in patients (pts) with IDH1/2m CCA, and IDH1m glioma or other solid tumors. Methods: Dose escalation (3+3 design) evaluated LY3410738 monotherapy in advanced IDHm CCA and other solid tumors (NCT04521686). Key objectives included determining the RP2D, safety, PK, PD (inhibition of plasma D-2-HG), and preliminary antitumor activity. Results: As of 28 July 2022, 80 pts including 42 with CCA (33 IDH1m, 9 IDH2m), 27 with glioma (IDH1m), and 11 other tumor types (IDH1m) received LY3410738 dosed at 25-600 mg QD or 300 mg BID. Pts were median 52 years of age (range, 23-80) with a median of 2 prior therapies (range, 1-7). 19% of CCA pts had received prior IDH1 inhibitor. Median time on treatment was 3.7 months (range, 0.1-19). No DLTs or treatment related deaths were observed; the MTD was not reached. Treatment emergent adverse events (TEAEs) ≥15% included nausea (35%), vomiting (21%), and decreased appetite (19%) and were mostly grade 1-2. Most frequent grade ≥3 TEAEs &gt;2% were anemia (4%), cholangitis (3%), headache (3%), decreased lymphocyte count (3%), and hyponatremia (3%). LY3410738 exposure was dose proportional. In pts with IDH1m cancers, LY3410738 achieved sustained D-2-HG inhibition at all dose levels, including in pts who received prior IDH1 inhibitor. In pts with IDH2m cancers, a higher dose (≥150 mg daily dose) was required for D-2-HG inhibition. Among the 42 pts with R/R CCA, the best response included 1 PR and 22 SD. Of the 22 glioma pts with contrast enhancing tumors, best response included 3 PR and 9 SD. Conclusions: LY3410738 demonstrated a favorable safety profile with potent and sustained D-2-HG inhibition in pts with IDH1/2m advanced solid tumors. Consistent with the expectations for IDH inhibitor monotherapy in this setting, CCA and glioma pts exhibited prolonged stable disease. RP2D evaluation is ongoing. Updated data on LY3410738 monotherapy will be presented at the meeting. Citation Format: Jordi Rodon, Lipika Goyal, Teresa Macarulla Mercade, Masafumi Ikeda, Shunsuke Kondo, Do-Youn Oh, Li-Yuan Bai, Makoto Ueno, Antoine Italiano, Kyriakos Papadopoulos, David Spigel, Sani H. Kizilbash, Rasha Cosman, Joon Oh Park, Li-Tzong Chen, Tomoya Yokota, Anita A. Turk, Chih-Yi Liao, Rachna Shroff, Anthony El-Khoueiry, Taroh Satoh, Antoine Hollebecque, Mitesh J. Borad, Nilofer Azad, Kurt A. Jaeckle, Herbert H. Loong, Jorge Adeva, Wei Peng Yong, Junjie Zhao, Hui Liu, Anna M. Szpurka, Ivelina Gueorguieva, Kamnesh R. Pradhan, Xiaojian Xu, James J. Harding. A first-in-human phase 1 study of LY3410738, a covalent inhibitor of mutant IDH, in advanced IDH-mutant cholangiocarcinoma and other solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr CT098.

Abstract Background Treatment patterns for intrahepatic cholangiocarcinoma (ICC) and extrahepatic cholangiocarcinoma (ECC) differ, but limited studies exist comparing them. This study examines differences in molecular profiling rates and treatment patterns in these populations, focusing on use of adjuvant, liver-directed, targeted, and investigational therapies. Methods This multicenter collaboration included patients with ICC or ECC treated at 1 of 8 participating institutions. Retrospective data were collected on risk factors, pathology, treatments, and survival. Comparative statistical tests were 2-sided. Results Among 1039 patients screened, 847 patients met eligibility (ICC = 611, ECC = 236). Patients with ECC were more likely than those with ICC to present with early stage disease (53.8% vs 28.0%), undergo surgical resection (55.1% vs 29.8%), and receive adjuvant chemoradiation (36.5% vs 4.2%) (all P &lt; .00001). However, they were less likely to undergo molecular profiling (50.3% vs 64.3%) or receive liver-directed therapy (17.9% vs 35.7%), targeted therapy (4.7% vs 18.9%), and clinical trial therapy (10.6% vs 24.8%) (all P &lt; .001). In patients with recurrent ECC after surgery, the molecular profiling rate was 64.5%. Patients with advanced ECC had a shorter median overall survival than those with advanced ICC (11.8 vs 15.1 months; P &lt; .001). Conclusions Patients with advanced ECC have low rates of molecular profiling, possibly in part because of insufficient tissue. They also have low rates of targeted therapy use and clinical trial enrollment. While these rates are higher in advanced ICC, the prognosis for both subtypes of cholangiocarcinoma remains poor, and a pressing need exists for new effective targeted therapies and broader access to clinical trials.