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ABSTRACT Many real‐world patients with advanced biliary tract cancer (BTC) are excluded by TOPAZ‐1 criteria; this study assessed cisplatin and gemcitabine plus durvalumab (CGD) efficacy and safety in these patients. Data from 1358 patients with advanced BTC treated with first‐line CGD across 55 international centers were retrospectively analyzed. Patients were classified as TOPAZ‐1‐in (meeting all inclusion criteria) or TOPAZ‐1‐out (meeting ≥ 1 exclusion criterion). Primary endpoints were overall survival (OS) and progression‐free survival (PFS); secondary endpoints included objective response rate (ORR), disease control rate (DCR), and safety. Furthermore, OS and PFS of the TOPAZ‐1‐out cohort were compared with reconstructed survival data from the phase III trial. 912 (67.1%) patients were classified as TOPAZ‐1‐in , and 446 (32.9%) as TOPAZ‐1‐out . After a median follow‐up of 14.5 months (95% CI: 13.7–36.5), OS was 16.1 months in TOPAZ‐1‐in and 12.5 months in TOPAZ‐1‐out (HR 0.69, 95% CI: 14.6–16.5, p = 0.0001); PFS was 8.2 versus 6.5 months (HR 0.73, 95% CI: 7.1–8.1, p < 0.0001). Median OS in the TOPAZ‐1‐out cohort (12.5 months) was nearly identical to the phase III trial experimental arm (12.9 months; HR 1.15, p = 0.13); for PFS the HR was 1.12 (95% CI 0.93–1.42; p = 0.09). Among TOPAZ‐1‐out patients, active infection, elevated bilirubin, and ECOG PS > 1 were linked to poorer OS, while no detrimental impact emerged for ALT/AST abnormalities, corticosteroid use, renal or hematologic parameters, or prior surgery within 6 months, suggesting treatment effectiveness was broadly maintained across clinical subgroups. Furthermore, TOPAZ‐1‐out patients experienced no significant increase in adverse events compared with the TOPAZ‐1‐in group. Real‐world data suggest CGD may be effective in TOPAZ‐1‐out patients, with no evident increase in toxicity, supporting the potential expanded use of the regimen in clinical practice.

ABSTRACT Surgery after response to first‐line chemoimmunotherapy may offer a potential curative option for patients with locally advanced biliary tract cancer (BTC) initially considered unresectable. However, robust real‐world evidence in this setting remains limited. We retrospectively analyzed patients with locally advanced BTC treated with first‐line cisplatin, gemcitabine, and durvalumab (CGD) across 55 centers in 12 countries. Endpoints included overall survival (OS), progression‐free survival (PFS), disease‐free survival (DFS) among resected patients, objective response rate (ORR), and the prognostic impact of surgery. A multivariable logistic regression model was developed to predict surgical conversion using baseline clinical and laboratory variables. Among 1358 screened patients, 219 had locally advanced disease and were included in the analysis. Median follow‐up was 14.5 months. ORR was 34.6%, with median PFS and OS of 10.0 and 20.7 months, respectively. Twenty‐four patients (10.9%) underwent surgical resection after systemic therapy. Median OS was 22.5 months in resected patients versus 19.9 months in those who did not undergo surgery. Median DFS after resection was 15.8 months. Pathological lymph node involvement was independently associated with shorter DFS. Larger baseline tumor size correlated with higher odds of radiological response but not with OS. An exploratory elastic‐net model retained four baseline variables and showed moderate discriminative ability for surgical conversion, with an apparent AUC of 0.72 and an optimism‐corrected AUC of 0.65. First‐line CGD enabled secondary resection in approximately 11% of patients with locally advanced BTC. A simple baseline model may support patient selection for conversion surgery, although prospective validation is needed.

776 Background: Surgery is the only potentially curative option for PC. However, only a minority of patients (pts) undergo resection with current perioperative (periop)-chemotherapy (CT). In the absence of phase III trials, selection between mFOLFIRINOX and gemcitabine/nab-paclitaxel (gem-nab) is based on limited evidence. We assessed whether NGS–based tumor profiling can guide tailoring of CT. Methods: pts with resected PC (resectable, borderline resectable, and downstaged locally advanced) that underwent Tempus xT, xF (DNA), and/or xR (RNA) testing were selected (89% tissue, 11% blood). Most samples (73%) were collected post-CT. Samples were stratified by KRAS status into KRAS -mutated ( KRAS mut) and KRAS wild-type ( KRAS wt). PD-L1 IHC was reported as tumor proportion score (TPS). Primary endpoint was median overall survival (mOS) defined from CT initiation to death with censoring of pts alive at the last follow-up or at a study cutoff of 5 years. Secondary endpoint was molecular profiling by KRAS status. Pearson chi-square and Wilcoxon rank-sum tests were used for descriptive comparisons; univariate Cox regression and log-rank tests (p<0.05) for survival. Results: We included 1,325 pts (median age 66 years [IQR 59–72]) with resected PC [stage II (15%), stage III (12%) and stage I (10%), unknown (62%)]. 95% had adenocarcinoma. Pts received neoadjuvant (50%), neoadjuvant plus adjuvant (26%), neoadjuvant with indeterminate adjuvant allocation (13%) or adjuvant CT (11%). First-line periop-CT was mFOLFIRINOX in 73% and gem-nab in 27% (median duration 4.3 months (mo) [range, 2.6–6.7]). KRAS mutations were present in 75% (G12X 91%: G12D 44%, G12V 34%, G12R 21%, G12C <1%). mOS was 26.7 mo (95%CI, 22.4-35.7) in the total cohort; KRAS mut pts showed a clinically meaningful worse mOS compared to KRAS wt [24.1 vs 35.7 mo; HR 1.61 (95%CI, 0.98 - 2.63); p=0.06]. In the KRAS G12D pts, mFOLFIRINOX showed a trend towards longer mOS compared to gem-nab [17.79 vs 14.53 mo; HR 0.75, (95% CI, 0.56 - 1); p=0.050]; no significant differences were observed in other KRAS subgroups. Compared to KRAS wt, KRAS mut pts were enriched for TP53 (76% vs 22%; p<0.001), SMAD4 (28% vs 5.8%; p<0.001), CDKN2A (33% vs 8.5%; p<0.001), MTAP deletions (7.7% vs 1.2%; p<0.001), and chromatin-regulator alterations ( ARID1A 7.8% vs 1.2%; p<0.001; KMT2C 2.5% vs 0.6%; p=0.034). KRAS wt pts were enriched for BRAF V600E (1.5% vs 0%; p<0.001). PD-L1 TPS ≥1% was more frequent in KRAS mut compared to KRAS wt (11.0% vs 8.1%; p=0.033). Conclusions: KRAS status does not predict benefit from mFOLFIRINOX vs gem-nab in resected PC. Interestingly, resected PC showed a higher prevalence of KRAS wt compared to the metastatic setting. KRAS status is associated with distinct profiles of potentially targetable co-alterations. These findings may suggest the integration of genomic profiling in clinical trials to develop biomarker-driven tailored strategies in the early stage.

679 Background: DNA-damaging agents improve outcomes in metastatic pancreatic cancer (mPC) with homologous recombination repair (HRR) deficiency, albeit use is limited to 6-9% of patients (pts) with BRCA1/2 or PALB2 mutations. We hypothesized that BRCA/PALB2 wildtype mPC may exhibit platinum sensitivity driven by altered HRR gene expression. We correlated HRR gene RNA profiles with real-world overall survival (rwOS) following first-line (1L) platinum therapy (PT). Methods: Tempus Lens, a platform used to query multimodal data from millions of de-identified patient records in the Tempus Database was used to identify mPC pts with wildtype somatic BRCA1/2 and PALB2 who had Tempus xT DNA and xR RNA testing. RNA-seq data were normalized to correct for assay/batch effects, quantified as transcripts per million (TPM) and reported as log2(TPM+1) for 17 HRR genes and GATA6 . Pts were classified as high and low expressors based on the top and bottom quartile gene expression. Pts were grouped as PT-treated (received 1L PT) or PT-naïve (never received PT). Real world overall survival (rwOS) was calculated from 1L start to death or loss to follow up. Risk set adjustment was applied to mitigate immortal time bias. Median rwOS was estimated using Kaplan-Meier and univariate Cox models. A multivariate Cox Proportional (CoxPh) model included PT use, RAS status, and expression of genes (as continuous variables). Results: Among 1,068 pts, the median age was 66 years and 609 (57%) received 1L PT. In low RAD51 expressors, PT-treated pts (n=136) had significantly longer rwOS than PT-naïve (n=112): 11.4 months (95% CI, 7.8–13.8) vs 8 months (95% CI, 5.5–9.0); p=0.028. In contrast, in high RAD51 expressors, rwOS was similar between PT-treated (n=150) and PT-naïve (n=97): 7.9 vs 6.9 months (p=0.236). High GATA6 expression was also associated with improved rwOS in PT-treated pts vs PT-naïve: 13.5 vs. 9.3 months; p=0.011. In multivariate analysis, increased GATA6 expression remained a positive predictor of rwOS (HR 0.82; 95% CI, 0.76–0.88; p<0.001), and high RAD51 expression was associated with shorter rwOS with PT (HR 1.18; 95% CI, 1.01–1.39; p=0.043). Conclusions: In BRCA/PALB2 wt mPC, transcriptomic profiling identified low RAD51 and high GATA6 expression as predictors for improved rwOS when treated with PT. Integrating these biomarkers may improve development of DNA-damaging therapies beyond canonically defined HRD. Hazard ratios of mPC mortality by selected HRR genes estimated by multivariate CoxPh models. HR 95% CI p value 1L PT (vs PT-naïve) 0.87 0.75, 1.00 0.054 BRCA1 1.15 0.98, 1.35 0.079 BRCA2 0.89 0.77, 1.04 0.14 GATA6 0.82 0.76, 0.88 <0.001 NBN 0.97 0.81, 1.15 0.7 RAD51 1.18 1.01, 1.39 0.043 RECQL4 0.94 0.84, 1.04 0.2 Any RAS mutation 1.43 1.14, 1.81 0.002

599 Background: Biliary tract cancers (BTC) remain aggressive malignancies with limited treatment options. Alterations in PIK3CA are implicated in tumor progression across solid tumors, but their prognostic impact in BTC remains unclear. We investigated the association of PIK3CA alterations(alt), alone and in combination with TP53 and ARID1A , with survival outcomes in advanced BTC. Methods: We conducted a retrospective analysis of 1,079 patients with advanced BTC treated with first-line chemotherapy (CT) or chemoimmunotherapy (CIO) across three sites in the USA, Japan, and Brazil. Genomic profiling was performed using next-generation sequencing on tissue and/or liquid biopsy samples. Survival outcomes were estimated by Kaplan-Meier analysis, with comparisons by log-rank testing and hazard ratios (HR) derived from Cox regression models. Results: PIK3CA alterations were identified in 11% (123/1,079) of patients. The median age at diagnosis was 68 yrs (range, 20–79), with 50% (62/123) female. The most common primary site was intrahepatic in 43.1% (53/123) while majority of patients received CT only 92.5% (111/123). When analyzed with TP53 , 68 pts had PIK3CA/TP53 co-alterations(co-alt), 501 had TP53 alt, 55 had PIK3CA alt alone, and 455 had neither PIK3CA nor TP53 alt (WT/WT). Overall survival (OS) was significantly worse in patients with PIK3CA alt, particularly in the setting of TP53 co-alt. Median OS (mOS) was 22.6 months(m) (95% CI, 20.4–24.8) for PIK3CA/TP53 WT, 15.9 m (95% CI, 11.6–18.5) for PIK3CA alt /TP53 WT, 14.6 m (95% CI, 13.1–19.5) for PIK3CA alt/ TP53 alt, and 17.1 m (95% CI, 15.5–18.8) for TP53alt/PIK3CA WT (p<0.001). In analyses with ARID1A , 32 pts had PIK3CA/ARID1A co-alt, 91 had ARID1A alt only, 120 had PIK3CA alt only, and 836 were WT/WT. PIK3CA/ARID1A co-alt tumors had a mOS of 12.8 m (95% CI, 9.1–NE) compared with 19.3 m (95% CI, 18.1–20.9) in PIK3CA WT /ARID1A WT (p=0.009). Multivariate analysis identified PIK3CA alt (hazard ratio [HR] 1.37, 95%CI 1.09–1.72; p=0.008), PIK3CA alt/ TP53 alt (HR 1.52 95% CI, 1.11–2.07; p=0.008), ARID1A alt/ PIK3CA WT (HR 1.40, 95% CI 1.08-1.82, p=0.011), and metastatic status (HR 1.82, 95% CI 1.52-2.19, P<0.001) as independent prognostic factors for shorter OS. Conclusions: In advanced BTC, PIK3CA alt were associated with significantly worse overall survival, particularly when co-occurring with TP53 or ARID1A alt. These findings establish PIK3CA as a prognostic biomarker of poor outcome and highlight the need to explore PI3K-targeted therapeutic strategies in BTC.

593 Background: TP53 and CDKN2A are the most frequently mutated tumor suppressors in BTC, each linked to poor outcomes. Their co-alteration remains unexplored due to the current single-gene classification. Methods: This is an international multicenter study involving 35 institutions across 3 continents (North America, Asia, South America). Genomic profiling was performed on tissue or blood samples using NGS. Patients (pts) were categorized as wild-type (wt) TP53/ wt CDKN2A (WT/WT) (42%), mutated (mut) TP53 /wt CDKN2A (45%), wt TP53 /mut CDKN2A (5%), mut TP53 /mut CDKN2A (8%). Associations between TP53 / CDKN2A status , clinical and genomic features were evaluated using Chi-squared/Kruskal-Wallis tests adjusted for multiple comparisons. Overall survival (OS) from start of first-line systemic therapy was analyzed by Kaplan–Meier and multivariate Cox regression (covariates: age, sex, stage, primary site, first-line treatment, TP53/CDKN2A status), p or q<0.05. Results: We included 1079 pts with BTC. Median age 66 years with intrahepatic BTC (46%), gallbladder cancer (25%), extrahepatic BTC (22%), undefined (6%), ampullary cancer (< 1%). Most had de novo metastatic disease (54%), followed by recurrent (38%) and locally advanced disease (8%). Treatment regimens included chemotherapy (87%), chemo-immunotherapy (12%) and immunotherapy alone (<1%). The most frequently actionable genes were HER2 (8%), IDH1 (7%), BRAF (6%), FGFR2 fusions (4%), MSI-High (H) (3%). HER2 alterations were prevalent in mut TP53 /wt CDKN2A vs WT/WT (11 vs 4%, q = 0.002). IDH1 alterations were more frequent in WT/WT vs TP53 mut/wt CDKN2A (10 vs 4%, q < 0.001). FGFR2 fusions were more common in wt TP53 /mut CDKN2A vs WT/WT (17 vs 6%, q < 0.001), mut TP53 /mut CDKN2A (17 vs 3%, q = 0.001) and mut TP53 /wt CDKN2A (17 vs 1%, q < 0.001). MSI-H was enriched in mut TP53 /mut CDKN2A vs wt TP53 /mut CDKN2A (11 vs 2%, q = 0.035), mut TP53 /wt CDKN2A (11 vs 3%, q = 0.002) and WT/WT (11 vs 2%, q < 0.001). TMB-H was more prevalent in mut TP53 /mut CDKN2A vs mut TP53 /wt CDKN2A (16 vs 8%, q < 0.001) and WT/WT (16 vs 3%, q < 0.024). There was no significant difference in ORR, DCR and PFS among the four groups. mut TP53 /mut CDKN2A had the shortest median OS, while WT/WT had the longest (Table). Only 14% of mut TP53 /mut CDKN2A received regimens including immunotherapy. Conclusions: mut TP53 /mut CDKN2A represents a high-risk subset enriched with MSI-H and TMB-H pts, underscoring the need to prioritize the development of immunotherapy strategies. TP53 / CDKN2A status is prognostic, stratifying patients into distinct survival groups and supporting NGS use in the first-line setting. mOS (months) (95% CI) HR (95% CI) P-value WT/WT 21.4 (19.0-24.4) reference wt TP53 /mut CDKN2A 17.3 (12.4-25.9) 1.16 (0.79-1.71) 0.442 mut TP53 /wt CDKN2A 17.4 (16.0-19.2) 1.21 (1.01-1.45) 0.040 mut TP53 /mut CDKN2A 13.8 (11.5-18.1) 1.54 (1.13-2.09) <0.001

ABSTRACT Background We recently published the first real‐world multicenter and multi‐institutional study of cisplatin, gemcitabine, and durvalumab in patients with advanced biliary tract cancer (BTC). Here we present an expanded patient cohort with an increased sample size and longer median follow‐up. Methods The study population included patients with advanced BTC, who received cisplatin/gemcitabine plus durvalumab at 55 centers across 12 countries in Europe, the United States, and Asia. The primary endpoints of the study were progression‐free survival (PFS) and overall survival (OS). Secondary endpoints were overall response rate (ORR) and safety. Results Overall, 1358 patients were enrolled. Median PFS was 7.6 months (95% CI: 7.2–8.1), and median OS was 15.6 months (95% CI: 14.8–16.5). ORR was 35.6%, and DCR was 82.7%. Any grade AEs occurred in 1213 patients (89.3%). Grade 3–4 AEs occurred in 597 patients (43.2%). The rate of immune‐related AEs (irAE) was 20.3%. Grade 3–4 irAE occurred in 3.0% of patients. At the multivariate analysis for OS, normal albumin level (HR 0.68, 95% CI 0.57–0.81, p < 0.0001), CEA levels within normal ranges (HR 0.68, 95% CI 0.57–0.82, p < 0.0001), NLR < 3 (HR 0.62, 95% CI 0.52–0.74, p < 0.0001), ECOG PS 0 (HR 0.51, 95% CI 0.42–0.61, p < 0.0001), and prior surgery (HR 0.80, 95% CI 0.65–0.99, p = 0.036) were positive prognostic factors. Conclusion The updated findings, derived from an expanded cohort, further support the adoption of durvalumab in combination with gemcitabine and cisplatin in routine clinical practice, reinforcing the efficacy and safety outcomes demonstrated in the phase III TOPAZ‐1 trial.

Abstract Molecular profiling reveals that up to 40% of advanced biliary tract cancers (BTCs) harbor actionable genomic alterations amenable to matched targeted therapies. However, conventional trial designs typically evaluate these agents in pretreated populations, resulting in approvals for later-line use. Notably, 25–44% of patients with advanced BTC may become ineligible for treatment after first-line therapy due to disease progression or functional decline, thus the real-world survival outcomes with matched therapies remains poorly characterized. This international collaborative study includes data from Mayo Clinic, Duke Cancer Institute, and National Cancer Center East (Japan), as well as a combined dataset from the SCRUM-Japan GOZILA, MONSTAR-SCREEN-1, and MONSTAR-SCREEN-2 projects. We assessed overall survival (OS) of patients based on the presence of actionable alterations and the receipt of matched therapy. To adjust for confounding, we applied propensity score weighting with inverse probability of treatment and multivariate Cox regression modeling, controlling for age, sex, tumor location, prior resection, and mutational subgroup. Among 1,049 patients that were analyzed, 358 (34.1%) harbored actionable alterations, with 160 (44.7%) receiving matched targeted therapy. The matched group (patients with actionable tumors who received a matched therapy) were significantly associated with longer median OS (23.3 months; 95% CI: 19.5–30.4) compared to the unmatched group (14.7 months; 95% CI: 12.8–17.9) and those with non-actionable tumors (17.1 months; 95% CI: 15.5–18.7; HR 0.57, 95% CI: 0.46–0.71; p < 0.0001). The unmatched group also was associated with the lowest three-year OS rate (13% vs. 35% in matched and 19% in actionable groups, respectively; p<0.0001). On multivariable analysis with patients who received ≥2 lines of therapy, receipt of matched therapy remained an independent predictor of improved OS (HR 0.62; 95% CI 0.43–0.90). These findings support the early integration of targeted therapies in BTC management and underscore the need to overcome systemic barriers to treatment access.

Abstract Purpose: Isocitrate dehydrogenase (IDH) 1/2–isoform inhibitors have clinical efficacy in IDH1/IDH2-mutated neoplasms. However, primary resistance and secondary resistance limit their therapeutic potential. LY3410738, an oral, brain-penetrant, dual IDH1/IDH2-mutated isoform-selective inhibitor, was designed to overcome resistance. Patients and Methods: This global, multicenter, open-label, phase I study of patients with IDH-mutant solid tumors evaluated LY3410738 as monotherapy (dose escalation) for advanced solid tumors in combination with cisplatin–gemcitabine (CISGEM) for newly diagnosed cholangiocarcinoma or with durvalumab for relapsed/refractory cholangiocarcinoma (dose expansion; NCT04521686). Primary objectives were the maximum tolerated dose, recommended phase II dose, and preliminary antitumor activity. Safety, pharmacokinetics, inhibition of D-2-hydroxyglutarate, and ctDNA were assessed. Results: Overall, 119 patients received LY3410738 alone (N = 94) or in combination with CISGEM (N = 19) or durvalumab (N = 6). No dose-limiting toxicities were observed; the maximum tolerated dose was not determined. Common adverse events included nausea, vomiting, and decreased appetite. Overall response rates of 5.2% and 11.1% and disease control rates of 56.9% and 63.0% were observed for patients with relapsed/refractory IDH1- or IDH2-mutant cholangiocarcinoma or IDH1-mutant glioma, respectively. D-2-hydroxyglutarate normalization was rapid and durable. In dose-expansion cohorts, combination treatments were tolerable, with one dose-limiting toxicity in the durvalumab cohort. LY3410738 plus CISGEM demonstrated a response rate of 42.1%, a median duration of response of 8.1 months, and a median progression-free survival of 10.2 months for patients with newly diagnosed IDH-mutant cholangiocarcinoma. Conclusions: LY3410738 demonstrated largely cytostatic antitumor activity in IDH1- or IDH2-mutated cholangiocarcinoma and IDH1-mutated gliomas. LY3410738 plus CISGEM exhibited favorable antitumor activity in patients with treatment-naïve IDH-mutated cholangiocarcinoma, warranting further exploration as a treatment strategy.