Biology-driven stratification of advanced biliary tract cancer treated with nab-paclitaxel plus gemcitabine-cisplatin: A prospective observational cohort study.

Background: Biliary tract cancer, typically diagnosed at advanced stages with a poor prognosis, has witnessed a glimmer of hope in the progress of immune checkpoint inhibitors (ICIs). Yet, their limited response rates necessitate the search for effective biomarkers to refine patient selection. Methods: A total of 125 patients with a confirmed histological diagnosis of unresectable advanced or metastatic biliary tract cancers (BTC) who received first-line ICIs in combination with chemotherapy (chemoimmunotherapy) were prospectively enrolled. All baseline samples from 125 patients underwent targeted DNA sequencing, with an additional 62 patients undergoing RNA sequencing, and 85 patients had accessible mIHC data. The associations between molecular characteristics and the response to chemoimmunotherapy, progression-free survival (PFS) and overall survival (OS) were evaluated. Results: The cohort had a median age of 63 years (range from 34 to 82) and 52.8% (66/125) were male, including 54 with gallbladder cancer, 57 with intrahepatic cholangiocarcinoma, and 14 with extrahepatic cholangiocarcinoma. The median duration of follow-up was 14.8 months for the entire cohort, with the median PFS and OS of 6.9 months (95%CI: 6.2-7.9) and 11.8 months (95%CI: 10.3-14.8), respectively. The most mutated genes were TP53 (64/125, 51.2%), KRAS (34/125, 27.2%), ERBB2 (18/125, 14.4%), and ARID1A (17/125, 13.6%). Mutations of TP53 (51.2%, p = 0.042), BRCA2 (4.8%, p = 0.002), cytokine genes (6.4%, p = 0.004), and high tumor mutation burden (p = 0.072) demonstrated significant correlation with chemoimmunotherapy response. KRAS G12D mutations (PFS: P < 0.001; OS: P = 0.034) and ARID1A loss-of-function mutations (PFS: P = 0.009; OS: P = 0.012) were adverse survival factors, while high CXCL9 or CTLA4 expression was associated with response (CXCL9, P = 0.014; CTLA4, P = 0.067), improved PFS (CXCL9, P = 0.018; CTLA4, P = 0.008), and longer OS (CXCL9, P = 0.010; CTLA4, P = 0.008) under chemoimmunotherapy. Patients were classified into three subtypes using the identified survival biomarkers. Among them, Type I patients, characterized by the absence of KRAS G12D or ARID1A mutations but expressing high levels of CTLA4 or CXCL9, demonstrated the best outcomes under chemoimmunotherapy. Interestingly, further RNA analysis suggested that elevated CXCL9 expression correlated with heightened immune checkpoint expressions, including CTLA4, PD-L1, and PD-1 (all P < 0.001), as well as increased tumor microenvironment immune activity, findings validated in two additional independent patient cohorts both internal and external. Conclusions: Our study revealed predictive biomarkers relevant to the response and efficacy of immune checkpoint inhibitors in combination with chemotherapy in advanced biliary tract cancer. Citation Format: Jieer Ying, Qi Xu, Jiaojiao Ni, Hanlin Chen, Chaoqun Li, Yanru Xie, Qinhong Zheng, Jianying Jin, Junrong Yan, Xiaoying Wu, Qiuxiang Ou, Li Yuan, Wei Zhuo, Haimeng Tang. Multi-omics analysis uncovers predictive biomarkers for the efficacy and outcomes of immune checkpoint inhibitor in combination with chemotherapy in advanced unresectable biliary tract cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5132.

Cisplatin, gemcitabine, and durvalumab combination is a standard first-line treatment for advanced biliary tract cancer. This study aimed to assess the impact of genetic alterations on outcomes in patients with advanced biliary tract cancer treated with cisplatin, gemcitabine, and durvalumab in real-world clinical practice. Patients with unresectable, locally advanced, or metastatic biliary tract cancer treated with cisplatin and gemcitabine plus durvalumab across 39 centers in 11 countries in Europe, the United States, and Asia were included in this analysis. The cohort included 513 patients with advanced biliary tract cancer. The 5 most frequently altered genes were TP53 (22.1%), KRAS (13.7%), CDKN2A/B (13.6%), ARID1A (12.2%), and IDH1 (9.2%). In multivariate analysis, SMAD4 mutations were associated with improved progression-free survival (PFS) (hazard ratio [HR] = 0.49, P = .018) and overall survival (HR = 0.11, P = .023), while TP53 mutations were linked to worse PFS (HR = 1.62, P = .0047) and TERT mutations to worse overall survival (HR = 8.92, P = .0012). No other genomic alterations were statistically associated with outcomes. Subgroup analysis showed that TP53 mutations negatively affected PFS and overall survival in intrahepatic cholangiocarcinoma, while KRAS mutations were associated with poorer PFS in extrahepatic cholangiocarcinoma. No gene alterations were linked to outcomes in gallbladder cancer. This large-scale analysis, with comprehensive molecular profiling, supports the positive prognostic impact of SMAD4 mutations for PFS and overall survival and highlights the negative prognostic roles of TP53 (PFS) and TERT (overall survival) mutations, providing valuable insights for personalized treatment strategies in biliary tract cancer.

4106 Background: Advanced biliary tract cancers (BTC) are lethal cancers with limited treatment options and short survival. Median progression-free survival (mPFS) in the ABC-02 trial was 8.0 months with gemcitabine-cisplatin (GC) and 5.0 m with gemcitabine alone in the front-line setting. The ABC-06 trial showed mPFS of 4.0 m with second-line FOLFOX. TP53 mutation is known to be associated with poor prognosis in other cancers, but its impact on survival in advanced or metastatic BTC has not been detailed. Methods: Mutational profiles were obtained from a retrospective database collected via an institutional DNA/RNA sequencing panel, FoundationOne, or Guardant360. Out of 149 patients with TP53 mutations in BTC, 90 had advanced or metastatic BTC treated at a single institution between 2015 and 2021. These patients were not candidates for surgery, radiation, or liver-directed therapy. Results: Intrahepatic, hilar, distal, and gallbladder cancer diagnoses were confirmed in 66, 11, 10, and 3 patients. Median age was 63, with a male:female ratio of 1:1. Poorly, moderately, and well-differentiated adenocarcinomas were found in 62, 20, and 1 (not available in 7 patients). The most common TP53 mutations were R175H (n = 5) and R248Q (n = 4). Common co-mutated genes included KRAS (n = 15), ARID1A (n = 15), FGFR2 fusion (n = 14), IDH1 (n = 13), BAP1 (n = 10), CDKN2A (n = 9), and HER2 amplification (n = 8). Microsatellite unstable (MSI-H) tumors were found in 3 patients. The median tumor mutational burden was 2.5/Mb. Patients received front-line GC (n = 54), GC-nab-paclitaxel (GAP, n = 14), FOLFIRINOX (n = 3), and GC with targeted or trial therapy (n = 11, e.g. trastuzumab). mPFS with front-line therapy was 5.0 m (n = 90); it was 4.7 m with GC and 5.1 m with GAP. Patients who had co-mutated IDH1 or FGFR2 fusion had longer mPFS (9.5 and 6.9 m, respectively) than those who did not (n = 63, 3.7 m, p < 0.05) from front-line chemotherapy. mPFS after second-line FOLFOX (n = 17) and FOLFIRI (n = 10) was 2.1 and 1.9 m, respectively, and mPFS after third-line FOLFOX/FOLFIRI was 1.8 m (n = 8). The median overall survival (OS) of patients with co-mutated FGFR2, IDH1, or neither was 34.5, 22.0, and 13.1 m, respectively (p < 0.05). TP53-mutated BTC with mutations other than FGFR2/IDH1 did not show statistically significant difference in PFS or OS. Conclusions: Patients with TP53-mutated advanced BTC have shorter PFS than those without TP53 mutation in front and further-line settings. The presence of co-mutated FGFR2 or IDH1 is associated with improved PFS with chemotherapy (not FGFR/IDH1 inhibitors) and longer OS. Other co-mutations do not appear to have a survival benefit. It is crucial for clinicians to take into account the worse prognosis with TP53 mutation before starting front-line therapy in patients with advanced BTC and consider early clinical trial options.

4095 Background: Despite that PD-1/L1 inhibitors combined with chemotherapy have been approved as first-line(1L) treatment for advanced biliary tract cancer (BTC), the overall survival benefit remains limited, particularly for patients with gallbladder cancer. Ivonescimab, a tetrameric bispecific antibody targeting PD-1 and VEGF, has the potential to produce complementary and synergistic anti-tumor effects through both pathways. This study aimed to evaluate the safety and efficacy of ivonescimab in combination with chemotherapy in advanced BTC. Methods: This was an open-label, multi-center phase II study in patients with unresectable locally advanced and metastatic BTC. Ivonescimab was administered every 3 weeks for up to 8 cycles, along with gemcitabine and cis-platinum. After that, ivonescimab monotherapy was given until disease progression or unacceptable toxicity. The primary endpoints were safety and objective response rate (ORR) by RECIST v1.1. Secondary endpoints included duration of response (DoR), disease control rate (DCR), time-to-response (TTR), progression-free survival (PFS), and overall survival (OS). Results: As of Nov 26, 2023, a total of 22 pts with advanced BTC were enrolled in the study. The median age was 65.0 years (range, 47-75), 81.8% of patients had ECOG of 1. All patients had initially unresectable disease status, 54.5% of patients had intrahepatic cholangiocarcinoma, 4.5% of patients had extrahepatic cholangiocarcinoma and 40.9% of patients had gallbladder cancer at baseline. The median follow-up time was 10.7 months, and the median exposure time of ivonescimab was 7.2 months. A total of 86.4% (19/22) of patients experienced at least one grade 3 or higher treatment-related adverse event (TRAE), but none led to discontinuation treatment or death. The most common grade 3/4 TRAEs with a frequency of at least 10% included white blood cell count decreased (50.0%), neutrophil count decreased (50.0%), anemia (40.9%), platelet count decreased (22.7%), and hypertension (13.6%). The ORR by investigator assessment was 63.6% (14/22) regardless of PD-L1 status, with an ORR of 77.8% (7/9) for gallbladder cancer patients specifically. The DCR was 100% (22/22). The median PFS was 8.5 months (95% CI, 6.8-9.9), with a 6-month PFS rate of 84.2% (95% CI, 58.7-94.6). The median OS was 16.8 months (95% CI, 9.8- NE), with a 9-month OS rate of 81.8% (95% CI, 58.5-92.8). Conclusions: Ivonescimab combined with chemotherapy as 1L treatment demonstrated promising efficacy in pts with advanced BTC. Further trials to validate the efficacy and safety are warranted. Clinical trial information: NCT05214482 .

4104 Background: Nab-paclitaxel plus gemcitabine-cisplatin (GemCis/nab-P) showed promising clinical outcomes in phase II trials for advanced biliary tract cancer (BTC) but did not demonstrate superiority over the control treatment in subsequent phase III clinical trials.In this study, we investigated predictive biomarkers of response to GemCis/nab-P in patients with advanced BTC using comprehensive genomic and transcriptomic analyses. Methods: This prospective cohort study (NCT04871321) enrolled 119 patients with advanced BTC who received GemCis/nab-P at CHA Bundang Medical Center, Korea from July 2021 to December 2022. Targeted genomic (Oncomine Comprehensive Assay) and whole-transcriptome sequencing data for tissue samples collected before the initiation of systemic chemotherapy were used for biomarker discovery (n = 108). To identify genomic and transcriptomic features related to overall survival (OS) and progression-free survival (PFS), the log-rank test, Cox proportional hazards model, and Lasso Cox regression model were used. Results: Among the 119 enrolled patients, 39.5% had intrahepatic cholangiocarcinoma, 37.0% had extrahepatic cholangiocarcinoma, and 23.5% had gallbladder cancer. Most patients had metastatic or recurrent disease (68.9%). The median follow-up duration was 23.7 months (range 0.8–30.2), median PFS was 8.3 months (95% Confidence interval (CI), 7.0–11.5), and median OS was 19.8 months (95% CI, 15.3–not reached). The most common genetic aberrations were TP53 (53.7%), KRAS (29.6%), and ARID1A (16.7%) alterations. TP53 mutations were associated with a poor OS (p = 0.001) and PFS (p = 0.005). In the transcriptome analysis, genes associated with immune responses, especially tumor-associated macrophages, were upregulated in patients with worse OS and PFS. We constructed a Lasso-Cox regression model and identified VSIG4 (hazard ratio (HR): 3.0, p = 2.0 × 10-4 for OS; HR: 2.4, p = 4.0 × 10-4 for PFS), ITGA3 (HR: 2.6, p = 0.001 for OS; HR: 1.7, p = 0.020 for PFS), and CCL8 (HR: 1.6, p = 0.110 for OS; HR: 1.6, p = 0.039 for PFS) as effective predictors of poor clinical outcomes during GemCis/nab-P treatment. Conclusions: GemCis/nab-P showed promising survival outcomes in advanced BTC. Further, patients with TP53 mutations or high tumoral levels of VSIG4, ITGA3, and CCL8 showed a poor prognosis after GemCis/nab-P treatment. Clinical trial information: NCT04871321 .

292 Background: Anti-angiogenic agents have been clinically investigated in combination with anti-PD-1/L1 mAbs due to their immuno-modulatory effects. Anlotinib (A), a potent oral multi-target tyrosine kinase inhibitor, has anti-angiogenic properties and anti-tumor efficacy with a favorable toxicity profile. The combination of A and TQB2450 (T), an anti-PD-L1 mAb, exhibited superior tumor growth suppression compared to either monotherapy in murine models. This ongoing phase 1b study cohort is aimed to assess the safety and efficacy of A+T in pts with advanced BTC. Methods: In this study cohort, patients (pts) with previously treated, advanced BTC were enrolled. A 3+3 dose escalation was used to determine the maximum tolerated dose (MTD) and a recommended phase 2 dose (RP2D) in a dose-escalating stage. Additional pts were enrolled in a dose-expansion stage to further establish the safety and determine the preliminary efficacy. Oral A of 10 and 12 mg was administered once daily for 14 days on / 7 days off with intravenous T of 1200 mg every 3 weeks. The primary endpoint was dose-limiting toxicity (DLT) during first cycle (first 3 weeks) to estimate the MTD, RP2D and overall response rate (ORR). Tumor response was assessed according to RECIST version 1.1 and iRECIST. The Secondary endpoints were progression-free survival (PFS), disease control rate (DCR) and safety. Results:25 pts were enrolled (8 with intrahepatic cholangiocarcinoma [IHCC]; 8 with extrahepatic cholangiocarcinoma [EHCC]; 9 with gall bladder cancer [GBC]) until August 2020. Median number of prior lines of therapy was 1 (range 1-5). During dose-escalation, no DLT was observed and 12 mg anlotinib was determined as RP2D for expansion. Among 24 evaluable pts (with at least once tumor assessment), 3 had achieved complete response (CR) and 7 had partial response (PR), which were all treated by 12 mg anlotinib plus TQB2450, 8 had stable disease (SD) and 6 had progression disease (PD). ORR was 41.67% and DCR was 75%. 10 pts were still on treatment. The median PFS was 240 days (95% CI, 83~NR).Treatment-related adverse events (TRAEs) occurred in 83.3% of pts (G3/4 in 16.7% [4/24], and leading to treatment discontinuation in 4.2% [1/24]). The most common TRAEs were hypertension (33.3%), decreased white blood cell counts (25.0%), increased TBIL (20.8%), decreased neutrophil counts (20.8%), increased DBIL (12.5%), and increased IBIL (12.5%). Conclusions: A+T had a manageable safety profile and encouraging antitumor efficacy in pts with previously treated, advanced BTC. No unexpected AEs were identified beyond the established safety profile for each agent. Clinical trial information: NCT03996408.

Multidisciplinary management in the treatment of intrahepatic cholangiocarcinoma.

4597 Background: Patients with advanced or metastatic BTC who progress on first-line (1L) gemcitabine-based doublet chemotherapy have few 2L treatment options. Varlitinib is a reversible small molecule pan human epidermal growth factor receptor (HER) inhibitor with low nanomolar potency against HER1 (EGFR), HER2 and HER4 with promising early results in advanced BTC. Methods: TreeTopp (NCT03093870) was a global, multicenter, double blind phase 2 study in which patients with advanced BTC who progressed after 1L therapy that included ≥6 doses of gemcitabine, with radiographically measurable disease based on RECIST v1.1, ECOG PS 0 or 1 and albumin ≥3 g/dL were randomized (1:1) to varlitinib (300 mg BID) plus capecitabine (1000 mg/m2 BID 14 days on/ 7 off)(V+C) or placebo plus capecitabine (P+C). The dual primary endpoints were Objective Response Rate (ORR) and Progression Free Survival (PFS) defined as the time from randomization to radiological progression assessed by Independent Central Review. Secondary end points included Overall Survival (OS). Results: Overall, 127 patients were randomized (V+C, n = 64; P+C, n = 63) from May−Dec 2018 and demographics/baseline characteristics were generally well balanced, although the V+C arm had a lower proportion of females vs. P+C (31% vs. 48%). The odds ratio for ORR was numerically higher with V+C vs. P+C was 2.278 (9.4% vs. 4.8%, p = 0.42), the HR for PFS for V+C vs. P+C was 0.90 (median PFS, 2.8 vs. 2.8 months; p = 0.63), and the HR for OS for P+C vs. V+C was 1.11 (median OS, 7.8 vs. 7.5 months; p = 0.66). Although not powered to evaluate sub-group interactions, in sub-group analysis, V+C showed PFS benefit versus P+C in two sub-groups; gallbladder cancer (GBC, HR = 0.55, 95% CI: 0.25, 1.22; median PFS, 2.9 vs. 1.6 months) and females (HR = 0.59, 95% CI: 0.28, 1.23; median PFS, 4.1 vs. 2.8 months). There was no PFS benefit for V+C vs. P+C among males and non-GBC. Toxicities were generally balanced between arms apart from a slightly higher incidence of hyperbilirubinemia, diarrhea and fatigue in the V+C vs. P+C arm. Grade 3/4 toxicities were reported in 66% and 59% of patients in the V+C and P+C arms, respectively. Conclusions: V+C is well tolerated but did not improve ORR, PFS or OS vs. P+C in 2L advanced BTC. Exploratory analyses suggested that patients with GBC and female patients achieved comparatively higher median PFS with V+C vs. P+C. Clinical trial information: NCT03093870 .

378 Background: BTC is a rare, heterogenous cancer with poor prognosis. Reports on immunogenic features of BTC suggest checkpoint inhibition may result in antitumor immune responses, and limited clinical activity has been seen with single agents in advanced settings. Durvalumab (PD-L1 inhibitor) + GemCis showed promising antitumor activity in advanced BTC in a phase 2 study. TOPAZ-1 (NCT03875235) is the first global phase 3 study to evaluate first-line immunotherapy + GemCis in advanced BTC. Methods: In this double-blind study, pts previously untreated for unresectable locally advanced, recurrent, or metastatic BTC were randomized 1:1 to receive durvalumab (1500 mg every 3 weeks [Q3W]) or placebo + GemCis (Gem 1000 mg/m2 and Cis 25 mg/m2 on Days 1 and 8 Q3W) for up to 8 cycles, followed by durvalumab (1500 mg Q4W) or placebo until disease progression or unacceptable toxicity. Randomization was stratified by disease status (initially unresectable, recurrent) and primary tumor location (intrahepatic cholangiocarcinoma, extrahepatic cholangiocarcinoma, gallbladder cancer). The primary objective was to assess overall survival (OS). Secondary endpoints included progression-free survival (PFS), objective response rate (ORR), and safety. Results: At data cutoff for this interim analysis (11 August 2021), 685 pts were randomized to durvalumab + GemCis (n=341) or placebo + GemCis (n=344; Table). The primary objective was met: durvalumab + GemCis significantly improved OS vs placebo + GemCis (hazard ratio [HR], 0.80; 95% confidence interval [CI], 0.66–0.97; p=0.021). PFS was also significantly improved with durvalumab vs placebo (HR, 0.75; 95% CI, 0.64–0.89; p=0.001). ORR was 26.7% with durvalumab and 18.7% with placebo. Grade 3/4 treatment-related adverse events (TRAEs) occurred in 62.7% of pts receiving durvalumab and 64.9% of pts receiving placebo. TRAEs led to discontinuation of any study medication in 8.9% of pts receiving durvalumab and 11.4% of pts receiving placebo. Conclusions: In pts with advanced BTC, durvalumab + GemCis significantly improved OS and PFS vs placebo + GemCis with manageable safety, indicating durvalumab + GemCis may be a new first-line standard of care regimen. Clinical trial information: NCT03875235. [Table: see text]

e16112 Background: Gemcitabine and cisplatin (gemcis) has been the standard of care for biliary tract cancer (BTC) for over a decade. One US model predicted the total lifetime cost of gemcis per patient to be $54,077 in 2020 CAD, although not all costs were considered. Our study objectives included quantifying updated costs and health care resource utilization (HCRU) associated with advanced BTC using real-world, population-level data from Ontario databases. Methods: We conducted a retrospective population-level study of patients diagnosed with recurrent or unresectable/advanced BTC (gallbladder cancer [GBC], intrahepatic and extrahepatic cholangiocarcinoma [IHC and EHC], Ampulla of Vater [AoV]) between January 1, 2010 and December 31, 2019. Follow-up data were available until December 31, 2020. HCRU and costs were calculated from the start date of first line (1L) of BTC-specific systemic therapies to death or the end of March 31, 2020 whichever occurred first. A macro-based costing methodology (GETCOST) was used and the mean cost per patient was reported in 2020 Canadian dollars (CAD). Mean cost per patient was calculated from diagnosis till the end of follow-up or death. The total number of HCRU-specific encounters for all years was divided by the number of BTC patients who used that HRCU in order to report the mean number of HCRU encounters (e.g., cancer clinic visits and inpatient hospitalizations). Results: Of 2,142 advanced BTC patients identified, 1,968 were diagnosed with non-AoV cancers (GBC, IHC, EHC or general BTC not otherwise specified) and 174 patients were diagnosed with AoV cancer. The mean cost per patient for all 1L-treated patients was $36,662 ($36,378 for non-AoV compared to $40,092 for AoV patients). By 1L-specific therapies, the highest mean cost per patient was for patients on gemcitabine and taxane combinations (gemtaxane) at $44,190, followed by gemcitabine and cisplatin (gemcis) at $34,507, then FOLFOX or FOLFIRI (fol) at $39,002 and carboplatin and gemcitabine (gemcarb) at $30,905. Untreated patients had a mean cost per patient of $42,136. The mean number of cancer clinic visits per patient per year during 1L ranged from 9.7 (untreated) to 13.7 (gemcis), while the inpatient hospitalizations per patient per year during 1L ranged from and 1.5 (gemcarb, fol and gemtaxane) to 2.4 (untreated). Conclusions: This study reports Canadian-specific, real-world costs and HCRU results of over 2,000 BTC patients. While cost results were stratified by type of BTC (AOV and non-AOV) and type of 1L therapies, the mean cost per patient ranged from $30,905 CAD to $44,190 CAD and HCRU results indicated substantial mean number of cancer clinic visits and inpatient hospitalizations. Thus, BTC patients incur a significant economic burden to the patients and Ontario public payer health system.

365 Background: Treatment option for patients with advanced BTC is limited and prognosis is poor with a median survival of less than 1 year in the locally advanced or metastatic setting. It has been shown deregulation of the immune system plays an important role in the pathogenesis of BTC. This study aimed to investigate whether tremelimumab (Treme), anti-CTLA4, could be combined safely and feasibly with microwave ablation therapy to enhance the effect of anti-CTLA4 treatment in patients with advanced BTC. Methods: Patients with refractory BTC were enrolled in a study of monthly Treme (10mg/kg, IV, 6 doses), followed by 3-monthly infusions until off-treatment criteria were met. On day 36, patients underwent subtotal microwave ablation. Staging image was performed every 8 weeks. Adverse events (AEs) were collected and managed. Tumor samples and peripheral blood samples were collected to perform immune monitoring. Results: Twenty patients with refractory BTC were enrolled. Male: female ratio was 10:10 with median age 56.5 years (range 37-67). Six patients had extrahepatic cholangiocarcinoma (ECC), two patients had gallbladder cancer, whereas the remaining 12 patients had intrahepatic cholangiocarcinoma (ICC). No dose-limiting toxicities were encountered. The common AEs included lymphocytopenia, colitis, adrenal insufficiency, anemia, and elevated transaminases. The most common clinical toxicity was diarrhea. Sixteen patients were evaluable for response analysis, one (6%) patient achieved a confirmed partial response (lasting for 8 months), 6 (37.5%) achieved stable disease with the longest lasting for 9.2 months. Among all 20 patients, median progression free survival, time to progression, and overall survival were 3.4 months (95% CI 2.5-5.2 months), 3.3 months (95% CI: 2.5-4.6 months) and 6.0 months (95% CI 3.8-8.8 months) respectively in this small pilot cohort. T cell receptor (TCR) b screening showed Treme expanded TCR repertoire though non-significantly. RNA seq is ongoing and will be presented. Conclusions: Treme in combination with tumor ablation is a potential new treatment for patients with advanced BTC. TCR repertoire expansion induced by Treme may contribute to treatment benefit. Clinical trial information: NCT01853618.

Durvalumab plus gemcitabine and cisplatin in advanced biliary tract cancer (TOPAZ-1): patient-reported outcomes from a randomised, double-blind, placebo-controlled, phase 3 trial

e16285 Background: Biliary tract cancers (BTCs) are mainly divided into cholangiocarcinoma (CHOL) and gallbladder cancer (GBC). Genomic characteristics of advanced BTCs are still needed to be investigated in large cohorts. The association of genomic alterations with clinical outcome remains elusive in advanced BTCs. Methods: Next Generation Sequencing with targeted panels were conducted for 4350 cases with advanced BTCs. Homologous recombination deficiency (HRD), tumor mutation burden (TMB), microsatellite instability (MSI) and HLA-Ⅰ subtypes were determined. The association of genomic alterations with clinical outcome was investigated in a multi-institutional subset. Results: Compared with historical cohorts which included mainly early stage diseases, the frequencies of KRAS and TP53 mutation in advanced BTCs significantly increased. Compared with GBC, CHOL had significantly more mutations in RTK-RAS pathway but significantly less mutations in other oncogenic pathways such as PI3K, HIPPO, NOTCH, and WNT. The proportion of HRD and TMB in GBC were significantly higher than that in CHOL, but no significant difference was observed for the proportions of MSI and HLA-Ⅰ homozygote subtype. Mutually exclusive or co-occurring mutations (CM) were analyzed. Some CM of TP53 mutations were significantly associated with overall survival (OS). Tumors with such a mutation were defined as the CM subtype of TP53, which had poor prognosis in all patients and in patients treated by immune checkpoint inhibitors (ICIs). Frame_Shift mutations (FM) and Multi_Hit mutations (MM) of TP53 were common in advanced BTCs, which indicated better prognosis in both first-line and second-line immunotherapy. Patients with the FM/MM of TP53 also showed better objective response rate (ORR) than those with the CM of TP53 (80% vs. 0%) in immunotherapy. Therapeutically relevant alterations (TRAs) were further analyzed. The most common TRAs in GBC and CHOL were PI3KCA and KRAS mutations, respectively. GBC had more ERBB2 alterations including amplification and mutations than CHOL (13% vs. 5%; p < 0.001), but FGFR2 fusions were detected almost only in CHOL (34 cases vs. 1 case; p < 0.001). Generally, KRAS mutations and other TRAs in CHOL were mutually exclusive, while the co-occurence of PI3KCA and other TRAs were common in GBC. Compared to the wild-type, IDH1 mutations indicated better immunotherapy prognosis in BTCs. In contrast, ATM, MET, NF1, and NRAS mutations were associated with poor prognosis of immunotherapy. Importantly, patients with PI3KCA mutations cannot benefit from the treatment with ICIs. IDH1/ERBB2 mutations had significantly better ORR than their wild-types (100% vs. 46.4%, p = 0.027). Conclusions: We reported novel findings about genomic heterogeneity between advanced CHOL and GBC in a large cohort. TP53 mutation and several TRAs were biomarkers of prognosis and immunotherapy outcomes.

Introduction: Current standard chemotherapy for biliary tract cancer (BTC) has limited survival benefits, and the need for targeted therapies is increasing. This study investigated the genetic profiles and clinical implications of BRCA mutations in patients with advanced BTC. Methods: Targeted high-throughput sequencing was performed on samples obtained from 25 patients with advanced BTC who had received palliative first-line platinum-based chemotherapy. Results: Of the 25 patients, 16 (64.0%) were younger than 65 years of age and 16 (64.0%) were male. The BTC cases consisted of intrahepatic cholangiocarcinoma (9, 36.0%), extrahepatic cholangiocarcinoma (5, 20.0%), and gallbladder cancer (11, 44.0%). The median overall survival (OS) and progression-free survival (PFS) of all patients were 11.9 months (95% confidence interval [CI]: 9.2–14.6) and 5.6 months (95% CI: 3.8–7.3), respectively. Genomic alterations in TP53 (52.0%), BRCA (36.0%), ATM (32.0%), ERBB2 (24.0%), NOTCH1 (20.0%), and FGFR3 (20.0%) were frequently reported. TP53 and ATM mutations were associated with OS (TP53: hazard ratio [HR] 2.719, 95% CI: 1.074–6.881, p = 0.035; ATM: HR 2.780, 95% CI: 1.091–7.082, p = 0.032). Patients with BRCA mutations had a slightly improved PFS compared to those with intact BRCA (6.7 months [range, 2.7–10.7 months] vs. 5.3 months [range, 3.6–7.0 months], p = 0.090). However, there was no significant difference in OS between groups (BRCA mutant vs. intact: 10.6 months [range, 3.6–17.6 months] vs. 11.9 months [range, 7.5–16.3 months], p = 0.252). BRCA mutations were significantly associated with PFS in the multivariate analysis (HR 0.150, 95% CI: 0.034–0.655, p = 0.012). Conclusion: This study demonstrated that BRCA mutations might have a role as predictive biomarkers for palliative first-line platinum-based chemotherapy in patients with advanced BTC.

e16598 Background: Biliary tract cancers (BTC) arise from the epithelial lining of the biliary tree and include intrahepatic and extrahepatic cholangiocarcinoma, gallbladder cancer, and sometimes cancer of the ampulla of Vater. Although this is a closely related group of diseases, comparisons of risk factors, treatment, and mortality by disease site are limited. Methods: This retrospective cohort study used Surveillance, Epidemiology, and End Results (SEER) cancer registry data linked with Medicare claims. Patients aged ≥66 years with a pathologically confirmed diagnosis of advanced (stage III or IV) BTC from 2010 to 2015 were included and followed up through 2016. Patients with any SEER-reported cancer in the prior 2 years were excluded. Any outpatient systemic treatment during follow-up was identified using Medicare claims. Patients were followed up until death, end of follow-up, subsequent primary cancer, or switch to managed care. The Kaplan-Meier estimator was used to estimate unadjusted median survival. A Cox proportional hazards model was used to identify factors associated with survival. Results: There were 2,891 patients in the cohort (Table). Factors significantly associated with worse survival included older age, presence of mobility limitations, living in an area with > 30% of the people below poverty, higher comorbidity burden, and stage IV BTC (vs stage III). Factors significantly associated with better survival included history of cancer, intrahepatic BTC (vs extrahepatic), or ampulla of Vater BTC (vs extrahepatic). Conclusions: Survival in BTC is poor and many patients do not receive outpatient systemic therapy. Patients with gallbladder and extrahepatic BTC had worse median survival and were less likely to receive systemic therapy than those with intrahepatic or ampulla of Vater BTC. Fewer ampulla of Vater patients present with Stage IV disease which could be a contributing factor to the significantly longer survival. Prior work has demonstrated an association between history of some types of cancer and survival; additional research is needed to better understand this finding. [Table: see text]