Babiker, Hani M.

4085 Background: Cholangiocarcinoma (CC) is a rare disease with an increasing incidence among younger adults, which is poorly understood. Genomic profiling of tumors is both prognostic and predictive of benefit for targeted therapies. We investigated if there are clinical and molecular differences between younger vs older patients with CC. Methods: We collected TEMPUS genetic data via retrospective chart review from tumors in young vs old patients seen at our institution, defined as ≤50 vs > 50 years of age at time of diagnosis. We included patients diagnosed with CC between January 2008 and July 2024 with available clinical follow up and TEMPUS genetic sequencing data. We collected mutation data on the following actionable genes: FGFR2, IDH1/2, BRCA1, BRCA2, BRAF, ATM, ERBB2/3, and KRAS. Patient characteristics and gene expression variables were compared using Chi-square, Fisher’s exact and Wilcoxon rank-sum tests. Kaplan-Meier, log rank tests and a multivariable Cox model were used for survival analysis. This study was IRB exempt. Results: We included 410 patients, 84 in the young group with median age at diagnosis of 40.8 years, and 326 in the old group with median age 68.5 years. 91.5% of patients were white. There was no difference in BMI between groups, however the older group had higher rates of hypertension (15.5% vs 57.7%), hyperlipidemia (6.0% vs 49.7%), cardiovascular disease (1.2% vs 20.6%), and type 2 diabetes (6.0% vs 21.5%), (all p < 0.01). Primary sclerosing cholangitis was more common in the young group (26.2% vs 4.3%, p < 0.01). ECOG status of 0 at first treatment was seen in 65.3% of young vs 52.5% of old patients (p = 0.02). FGFR2 alterations were more common in the young group (17.9% vs 8.0%, p < 0.01), while ATM mutations were more common in old vs young (5.5% vs 0%, p = 0.03). There was no age difference seen for the other genetic alterations. Mean tumor mutational burden was higher in the old group (4.1 vs 3.8 mut/mb, p = 0.01). MSI-high was found in 2% of cases with no difference between groups. There was no significant difference in overall survival between age groups. There was a numeric difference in overall survival in stage IV patients, though not statistically significant (17.8 months vs. 16.3 months, p = 0.08). In a multivariable Cox analysis, female sex, earlier stage at diagnosis and clinical trial enrollment were associated with favorable prognostics. Conclusions: Our data highlight relatively low rates of comorbidities associated with metabolic dysfunction in younger adults with CC, suggesting alternative factors are likely to explain the increasing incidence of early-onset disease. FGRFR2 is a more common pathogenic alteration among the young and could inform targeted therapies. Younger patients with CC may not have improved survival outcomes compared to their older counterparts. This underscores the aggressive nature of CC and the need for more effective therapies to improve outcomes.

4166 Background: GN is a front-line therapy for aPDAC. A Phase I/II study demonstrated that GCN has a higher overall response rate and median overall survival (mOS). Our previous study found no difference in outcomes among patients with DNA damage repair gene mutations; however, stromal gene expression correlated with mOS in patients receiving GCN. Here, we further evaluate differences in the outcomes with GCN and GN by site of biopsy. Methods: PDAC samples (n = 4,463) were analyzed by NGS (NextSeq/NovaSeq) or RNA (NovaSeq) (Caris Life Sciences, Phx, AZ). Expression of stromal and related genes ( ACTA2, ADIRF, HAS2, IL-6, MMP-2, MMP-9, SPARC, STAT3, TBGB1, TGFB2, TGFBR3, IDO1, HLA-DRB4, VEGFB) from different biopsy sites [high expression (H) >50% of RNA transcripts per million] was correlated with outcomes to GCN or GN. mOS was obtained from insurance claims and calculated from first treatment to last contact. The hazard ratio (HR) was calculated by the Cox proportional hazards model, and p-values were calculated using the log-rank test. Results: 4325 patients [primary biopsy (PT), n = 1,878; non-liver metastatic biopsy (N-LM), n = 818; Liver biopsy (LM), n = 1,629] received GN while 138 patients (PT, n = 45; N-LM, n = 28; LM, n = 65) received GCN. GCN was associated with longer mOS than GN [∆: 5.2 months (m), HR: 0.76, 95% CI 0.63-0.92, p = 0.01]. GCN was associated with longer mOS compared to GN in LM (∆: 5.6 m, HR: 0.66, 95% CI 0.50-0.87, p = 0.003), but it was not significant in PT (∆: 4.6 m, p = 0.13) and N-LM (∆: 4.4 m, p = 0.35). Median MMP2 (38.5 vs. 163.1 vs. 162.2), VEGFB (14.4 vs. 16.9 vs. 16.2) and TGFBR3 (11.4 vs. 15 vs. 16.4) expression were lower in LM compared to PT and N-LM while TGFB1 (41.6 vs. 34.5 vs. 39.8) and IL6 (1.61 vs. 1.19 vs. 1.41) expression were highest in LM (p < 0.05). In LM, IL6 -H (∆: -11 m, p = 0.037) and TGFB1 -H (∆: -5.9 m, p = 0.10) were associated with worse post-GCN survival compared to GN (p = 0.82 and p = 0.57). Whereas, in N-LM, TGFBR3 -H trended towards longer post-GCN survival (∆: 12 m, p = 0.18), while ADIRF -H trended towards shorter post-GCN survival (∆: -12 m, p = 0.056) compared to GN (p = 0.42 and p = 0.10). While in PT, MMP2 -H (∆: 11.3m, HR: 0.46, p = 0.16), TGFB1 -H (∆: 11.3 m, HR: 0.33, p = 0.09), HLA-DRB4 -H (∆: 12.9 m, HR: 0.44, p = 0.11) and VEGFB -H (∆: 10.7, HR: 0.34, p = 0.09) trended towards longer post-GCN survival compared to GN ( MMP2 -H, ∆: 3.4 m, p = 0.03, TGFB1 -H, p = 0.661, HLA-DRB4 -H, p = 0.67, VEGFB-H , ∆: 1.3 m, p = 0.03). Conclusions: GCN is associated with improved mOS compared to GN, especially in LM.Stromal gene expression in the liver differs from that in N-LM and the pancreas. While high stromal gene expression trends towards worse post-GCN survival in LM, it is associated with improved survival in N-LM and PT. Further validation is needed to understand the impact of stromal gene expression in different tumor sites on survival outcomes and signature development.

10587 Background: The American Society of Clinical Oncology (ASCO) and NCCN recommend germline testing for patients (pts) with biliary tract cancers (BTC), particularly those diagnosed at a young age. Prior studies estimate that approximately 15% of pts with BTC harbor pathogenic germline alterations. Germline testing can identify hereditary cancer syndromes, guide targeted therapy, and inform family counseling. This study aimed to further characterize and describe the prevalence of pathogenic germline variants (PGVs) in patients with young-onset BTC (YO-BTC). Methods: We conducted a retrospective review of medical records for pts diagnosed with YO-BTC (ages 18–55) across all Mayo Clinic tri-sites from January 2014 to October 2024. Data collected included results from germline DNA sequencing, tumor genetic testing, demographics, history of other malignancies, and family history of cancer. The primary outcome was the identification of pathogenic germline mutations associated with cancer predisposition. Results: Among 239 pts with YO-BTC, the median age at diagnosis was 43 years (range 19–55), with 62% female and 65.2% identifying as white. Clinical germline testing (e.g., Invitae, Ambry, Myriad) was performed in 123 pts (51.5%), revealing PGVs in 15 pts (12.1%), variants of uncertain significance (VUS) in 30 pts (24.3%), and likely benign variants in 4 pts (3.2%). Among those with PGVs, DNA repair mutations were the most common findings (10/15), including ATM (4), CHEK2 (2), BRCA2 (2), BAP1 (1), and PALB2 (1). One pt had a Lynch syndrome-associated mutation (MSH6), and four had mutations in other cancer-related genes (MUTYH, HOXB13, RMRP, and PIK3CA). Tumor genomic profiling (via CARIS, TEMPUS, or FoundationOne) was performed in 9 pts with PGVs, detecting the variant in 4 (44%), while liquid biopsy (Guardant) identified the PGV in 4 of 6 cases (66.6%).The majority of PGV carriers had advanced BTC (14/15), with intrahepatic cholangiocarcinoma being the most prevalent (11/15), while 4 had extrahepatic cholangiocarcinoma. Additionally, most PGV carriers had a first- or second-degree relative with a prior history of malignancy (14/15), and 3 pts had a second malignancy. Of the 15 pts with PGVs, 4 had BTC associated with primary sclerosing cholangitis. Conclusions: In this large institutional series of YO-BTC, PGVs were identified in 12.1% of pts, demonstrating a significant yield from germline testing in this population. Notably, tissue and liquid biopsies demonstrated different detection rates for PGVs, underscoring the variability in PGVs reporting across platforms. Germline testing through CLIA-approved methods should remain the standard of care. DNA repair pathway mutations, particularly ATM, CHEK2, and BRCA2, were the most frequently identified PGVs, highlighting their role in the pathogenesis of YO-BTC and their potential to guide treatment decisions.

3011 Background: BMS-986504 selectively binds to the PRMT5-MTA complex, which represents a synthetic lethal target in MTAP -del cancer cells, while sparing MTAP– wild-type cells. In the first-in-human phase 1/2 CA240-0007 study in advanced, unresectable or metastatic solid tumors with homozygous MTAP -del, BMS-986504 was found to be well tolerated and demonstrated antitumor activity in multiple tumors. Here, we report clinical results and the first PK and PD analyses of BMS-986504 from the dose escalation and expansion phases of CA240-0007. Methods: Pts with measurable/evaluable disease and no available treatment (Tx) with curative intent were enrolled; 7 doses were evaluated (50 to 800 mg) in dose escalation. Objective response rate (ORR), disease control rate (DCR), duration of response (DOR), time to response (TTR), safety, PK, PD, including plasma SDMA were assessed. Results: As of 2 Dec 24, 152 heavily pretreated pts were enrolled across all doses: NSCLC (n = 34), PDAC (n = 41), cholangiocarcinoma (n = 12), and mesothelioma (n = 12) were the most common tumor types. With a median f/u of 9.0 mo (95% CI 7.6–9.9), continued durable antitumor activity and deepening tumor regression were seen across tumor types and doses (ORR = 23%, DCR = 70%, median DOR = 10.5 mo, TTR = 4.6 mo). No new safety signals were identified. Most Tx-related adverse events (TRAEs) were grade (Gr) 1 or 2; 13% had Gr ≥ 3 TRAEs (Gr 3 = 12%, Gr 4 = < 1%, Gr 5 = 0). Doses from 50 to 600 mg QD were assessed for PK/PD. The AUC (0-24) after multiple doses was approximately dose proportional at 200 to 600 mg, and the terminal t 1/2 after a single dose was approximately 24 h (table). There were dose-dependent reductions in predicted plasma SDMA, with the 400 and 600 mg doses approaching the plateau. Conclusions: With longer f/u, BMS-986504 continued to show increasingly durable antitumor activity. BMS-986504 demonstrated a favorable PK/PD profile, supporting QD dosing at 400 and 600 mg. These results support further investigation of BMS-986504 at 400 and 600 mg QD as a potential first-in-class synthetic lethal Tx option in pts with advanced solid tumors with MTAP -del. Clinical trial information: NCT05245500 . PK and PD. 50 mg QD 100 mg QD 200 mg QD 400 mg QD 600 mg QD PK after multiple doses t max a (min–max), h 2.0 (2.0–4.0)n = 3 2.0 (1.0–2.0)n = 3 2.0 (0.5–6.0)n = 8 2.0 (0.5–4.0)n = 10 2.0 (1.0–6.0)n = 10 C max , b ng/mL 107n = 3 377n = 3 685n = 8 1240n = 10 2110n = 10 AUC (0-24) , b h∙ng/mL 948 n = 3 3060 n = 3 7150 n = 7 11,800n = 10 26,700n = 9 AUC (0-24) , b,c h∙ng/mL/mg 19.0n = 3 30.6n = 3 35.8n = 7 29.5n = 10 44.6n = 9 Terminal t 1/2 after single dose, d h 21.7 n = 1 80.7 n = 1 21.5 n = 14 21.7 n = 14 24.1 n = 1 PD Translational exposure targets (C avgss ), X 0.08 0.21 0.5 1.1 1.7 Predicted plasma SDMA reduction, a % (90% PI) 30.0 (23.2–37.8) 38.8 (27.1–47.5) 48.3 (42.0–53.0) 55.0 (50.7–57.6) 57.4 (54.3–59.0) a Median. b Geometric mean. c Dose-normalized. d Arithmetic mean.

Tumor-Treating Fields (TTFields), a novel therapeutic avenue, is approved for therapy in Glioblastoma multiforme, malignant pleural mesothelioma, and metastatic non-small cell lung cancer (NSCLC). In pancreatic ductal adenocarcinoma (PDAC), several clinical trials are underway to improve outcomes, yet a significant knowledge gap prevails involving the cell-extracellular matrix (ECM) crosstalk. Herein, we hypothesized that treatment with TTFields influence this crosstalk, which is reflected by the dynamic alteration in nanomechanical properties (NMPs) of cells and the ECM in a co-culture system. We employed an ECM gel comprising collagen, fibronectin, and laminin mixed in 100:1:1 stoichiometry to co-culture of Panc1 and AsPC1 individually. This ECM mixture mimics the in vivo tumor microenvironment closely when compared to the individual ECM components studied before. A comprehensive frequency-dependent study revealed the optimal TTFields frequency to be 150 kHz. We also observed that irrespective of the ECM’s presence, TTFields increase cell membrane stiffness and decrease deformation several-folds in both Panc1 and AsPC1 cells at both 48 h and 72 h. Although adhesion for AsPC1 decreased at 48 h, at 72 h it was observed to increase irrespective of ECM’s presence. Moreover, it significantly alters the NMPs of ECM gels when co-cultured with PDAC cell lines. However, AsPC1 cells were observed to be more detrimental to these changes. Lastly, we attribute the stiffness changes in Panc1 cells to the membrane F-actin reorganization in the presence of TTFields. This study paves a path to study complex PDAC TME as well as the effect of various chemotherapeutic agents on such TME with TTFields in the future.

Abstract Background: Pancreatic ductal adenocarcinoma (PDA) is a disease with guarded prognosis with a 5-year overall survival (OS) of 3.1% in patients with metastatic disease. The need for innovative treatments for this lethal disease is paramount. TTFields is a novel treatment modality that employs low intensity, alternating, and intermediate frequency electrical fields that abrogates cancer cell proliferation through different mechanisms. These include inhibition of mitosis, disruption of cancer cell membranes, metabolomic dysregulation of cancer cells, and immunogenic activation of the tumor microenvironment (TME). TTFields are approved in glioblastoma multiforme, non-small cell lung cancer and malignant mesothelioma. The PANOVA trial demonstrated promising efficacy for TTFields plus chemotherapy in patients with PDA. A trial of GCN in patients with PDA demonstrated exceptional efficacy in patients with metastatic disease. Here in, we present our ongoing clinical trial investigating the safety and efficacy of TTFields plus GCN in patients with PDA (NCT04605913). Methods: This a phase I/II trial with an initial safety run-in phase followed by the phase II portion. The primary objective of the trial is to determine the safety (CTCAE v 5.0) of GCN plus TTFields. Secondary objectives include determining the 6-month progression free survival (PFS) rate, overall response rate (ORR, RECIST v1.1), 12-month survival rate, OS, and QOL (EORTC QLQ-C30, version 3.0.2.3). Inclusion criteria include PDA with liver metastasis (patients can have additional sites of metastasis), ECOG 0-1, measurable disease, and ability to operate the Novo TTF-100L (P)/Novo TTF-200T system. Treatment consisted of TTFields (150 kHz 18 hours/day) and GCN (G: 1000 mg/m2, C 30 mg/m2, and N: 150 mg/m2 every 2 weeks, 28 days cycle), followed by a maintenance phase after 6 months (G: 1000 mg/m2 every 2 weeks) plus TTFields until progression. Six patients were to be enrolled in the phase I portion and if ≤1/6 patients experienced a dose limiting toxicity (DLT, treatment emergent adverse event, or skin toxicity of Gr4), the plan would be to move to a phase II trial enrolling 34 more patients. If 2/6 patients experienced a DLT, 6 patients would be enrolled in dose level -1 (GCN plus TTFields for 9 hours/day followed by the maintenance treatment) and if tolerated the phase II portion would start with dose level -1 regimen. The phase I portion was completed without any DLTs and the trial is currently enrolling to the phase II portion. The total number of patients (40) was powered to the 6-months PFS rate and ORR (estimated using the lower bound of exact one-sided 90% confidence intervals). The goal is to "reject" a 6-month PFS rate of 66% and an ORR of 71% (based on previous GCN trial). Time-to-event endpoints will be assessed using the Kaplan-Meier method. Citation Format: Hani M. Babiker, Jason Starr, Jeremy Jones, Conor O’Donnell, Robert Jones, Jacqueline Boni, Lashundra Stewart, Josh Cameron, Oudom Kour, Kabir Mody, Robert R. McWilliams, Daniel H. Ahn, Tanios Bekaii-Saab, Mitesh J. Borad, Umair Majeed. A phase I/II pilot trial, single arm, open label, of gemcitabine, cisplatin, protein-bound paclitaxel (GCN) combined with Tumor Treatment Fields (TTFields) in patient with metastatic pancreatic adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_2):Abstract nr CT190.

Abstract BACKGROUND: Intrahepatic cholangiocarcinoma (ICC) is a rare but aggressive cancer with limited curative options outside of surgical resection. Trans-arterial radioembolization (TARE) with yttrium-90 is a promising treatment with retrospective data showing an overall survival (OS) of up to 30 months. The single arm prospective MISHPEC trial combined TARE with gemcitabine and cisplatin showed an overall response rate (ORR) of 39% at 3 months along with a median OS of 22 months. PDL1 inhibitor (Durvalumab) has shown modest benefit in addition to chemotherapy in unresectable cholangiocarcinoma with three-year OS of 15% based on the TOPAZ-1 trial. ICC is a biologically cold tumor; preclinical data indicates that Yttrium-90 TARE can alter tumor microenvironment making it conducive to effector T cell recruitment and function leading to enhanced efficacy of immunotherapy. This provides the biological rationale of combining yittrium-90 TARE with systemic immunotherapy involving dual PDL1 and CTLA-4 inhibitors. Here in, we present our ongoing clinical trial investigating the safety and efficacy of yttrium-90 TARE combined with Durvalumab and Tremelimumab in patients with ICC (NCT06058663). METHODS: In this phase 1 study, yittrium-90 TARE will be combined with Durvalumab and Tremelimumab in 16 patients with unresectable or oligometastatic ICC. Eligible patients with histologically confirmed measurable disease must not have received any prior local therapies and any immunotherapy with ECOG PS of 0 or 1, adequate liver (Child Class A, ALBI 1 or 2) and renal function. Patients should also have a favorable mapping angiography based on an angiosomal analysis. Ablative radioembolization would be performed at least a dose of greater than 205 Gy MIRD to &gt;75% of tumor. Study treatment with Tremelimumab (x 1 dose of 300mg total) + Durvalumab 1500mg monthly will continue until unacceptable toxicities, or disease progression for up to 24 months. Durvalumab and Tremelimumab will be infused in two alternate schedules after yittrium-90 TARE. In cohort 1 (3 patients) immunotherapy will be delivered within 24 hours of TARE. In cohort 2 (3 patients) immunotherapy will be delivered 2 weeks after TARE. Subsequent patients will be enrolled in either cohort 1 or 2 based on the safety signal from the first 6 patients. Primary goal of the study is to determine safety of this combination. Secondary goals include ORR per RECIST 1.1, progression-free survival, overall survival, infield and out of field response rate and downstaging to resection. Correlative studies include ctDNA at baseline along with evolution through treatment, pre and post treatment biopsies to look at tumor microenvironment and post treatment dose volume histograms. Three patients have been accrued in the study thus far. Citation Format: Umair Majeed, Jason Starr, Conor O'Donnell, Robert Jones, Jacqueline Boni, Josh Cameron, Oudom Kour, Mitesh Borad, Hani Babiker, Kabir Mody, Beau Toskich. Yttrium-90 radioembolization in combination with tremelimumab and durvalumab for treating patients with locally advanced, unresectable or oligo-metastatic intrahepatic cholangiocarcinoma who are not candidates for curative therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_2):Abstract nr CT189.

Abstract Background: Effective treatments (Tx) are needed for MTAP-del cancers (10-15% of all cancers). BMS-986504 (formerly MRTX1719) is a potential first-in-class MTA-cooperative protein arginine methyltransferase 5 (PRMT5) inhibitor that selectively binds to the PRMT5-MTA complex, a synthetic lethal target in MTAP-del but not MTAP-wild-type cells. In the first-in-human phase 1/2 CA240-0007 study, BMS-986504 was well tolerated and showed clinical activity in heavily pretreated pts across multiple advanced solid tumors with homozygous MTAP-del. Here, we report results of exploratory PD analyses of PRMT5 inhibition with BMS-986504 in CA240-0007. Methods: Pts with advanced, unresectable or metastatic solid tumors with homozygous MTAP-del received BMS-986504 (50 to 800 mg) in 3-wk cycles. Symmetric dimethylarginine (SDMA) and intron retention are known PD BMs of PRMT5 inhibition. Therefore, PD effects of BMS-986504 were assessed via changes in plasma and tumor SDMA levels (mass spec and IHC), intron retention, and gene expression (RNASeq) based on samples collected at baseline (BL) and cycle 2 day 1 (C2D1). Additional analyses correlating efficacy outcomes with PD results and select mutations at BL were performed in clinically evaluable pts as of 19-SEP-24. Results: Robust PD modulation of the PRMT5 pathway was observed with BMS-986504. Among pts with matched samples (n = 63), median plasma SDMA levels were reduced by 56% from BL (122.6 ng/mL) to C2D1 (53.8 ng/mL). There were dose-dependent reductions in median plasma SDMA with the greatest reductions at 400 mg QD (59.7% [n = 20]), 400 mg BID (61.9% [n = 9]) and 600 mg QD (59.1% [n = 14]). These PD effects were corroborated in the tumor. Median tumor SDMA levels decreased from an HScore of 285 at BL to 0 at C2D1. Consistent with the SDMA decreases, increased intron retention was observed in 9/11 pts with matched samples. BMS-986504 led to downregulation of several gene pathways including DNA repair and mitotic spindle formation, and MYC and E2F targets, as assessed by RNASeq. There was no significant change in expression of MAT2A, PRMT5, or other PRMT genes, suggesting a lack of compensation for PRMT5 inhibition through these genes. Responses were observed with BMS-986504 across EGFR, KRAS, and TP53 mutation subgroups. Additional correlative analyses among BMs and efficacy outcomes will be presented. Conclusions: BMS-986504 demonstrated robust PD effects across multiple doses and solid tumors which is consistent with the proposed mechanism of action. There was a trend of increasing plasma SDMA reduction across doses, with the greatest reductions observed at 400 mg QD and above. Together these results support further investigation of BMS-986504 at 400 mg QD and higher doses as a potential first-in-class synthetic lethal Tx option in pts with advanced solid tumors with MTAP-del. Citation Format: Jordi Rodón, Tyler Simpson, Ben George, Pasi A. Jänne, Kathryn C. Arbour, Konstantinos Leventakos, Kyriakos P. Papadopoulos, Melissa L. Johnson, Alexander I. Spira, Cesar A. Perez, Hani M. Babiker, Richard Zuniga, Candace L. Haddox, Tapsi Kumar, Yidi Qin, Wen-Chi Chou, Peter Olson, Kenna Anderes, Alice Wozniak, Curtis Chin, Ming Lei, Jason T. Henry. Pharmacodynamic (PD) and exploratory biomarker (BM) analysis of the PRMT5 inhibitor BMS-986504 in patients (pts) with advanced solid tumors with homozygous MTAP deletion (MTAP-del) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_2):Abstract nr CT079.

Tumor treating fields (TTFields), a noninvasive anticancer treatment modality, has received FDA approval for pleural mesothelioma, metastatic NSCLC following platinum-based therapy, newly diagnosed and recurrent glioblastoma multiforme. TTFields have also demonstrated potential benefits in other cancer types, including pancreatic ductal adenocarcinoma (PDAC). Although the PANOVA trial yielded positive results in PDAC patients, the mechanisms underlying these beneficial effects remain unclear. Severe desmoplasia is a hallmark characteristic of PDAC due to accumulation of excess extracellular matrix (ECM) caused by activated fibroblasts and cancer cells. This dense ECM contributes to an immunosuppressive tumor microenvironment (TME) and drug resistance, which ultimately leads to poor 5-year survival in PDAC patients. Our previous work with atomic force microscopy (AFM) showed that the nanomechanical properties of the ECM change dynamically based on its composition and the presence of PDAC cells, and vice versa. Herein, we prepared an ECM complex comprising of collagen, fibronectin and laminin at physiological concentrations. Following which, we investigated the alteration of stiffness of both PDAC cells and the ECM in presence of TTFields using an AFM. A frequency-dependent analysis of TTFields showed that a frequency of 150 KHz led to consistent decreases ECM stiffness at 48 and 72 hours. Next, we evaluated the influence of TTFields in PDAC cells alone. In Panc-1 cells exposed to TTFields for 48 and 72 hours, we observed a more than 6-fold increase in membrane stiffness compared to untreated controls. Additionally, AsPC-1 cells subjected to TTFields exhibited a greater than 2-fold increase in membrane stiffness at these time points. Furthermore, we have investigated influence of TTFields on PDAC cells and ECM components in a co-culture model. In this co-culture scenario for Panc-1 cells, TTFields increase membrane stiffness by 5-fold compared to untreated at these time points. Also, AsPC-1 cells demonstrated a 1.5-fold increase in membrane stiffness in the presence of TTFields compared to the untreated. Lastly, we also evaluated the influence of cells on the ECM stiffness in the presence of TTFields. It significantly increased the ECM stiffness in presence of Panc-1 co-culture by 1.3-folds compared to control. We also observed 3- and 4-fold increase in ECM matrix stiffness when co-cultured with AsPC-1 for 48 and 72 hours from TTFields, respectively compared to control. In conclusion, TTFields significantly modulate the stiffness of PDAC cells and the ECM, both individually and in co-culture. Citation Format: Tanmay Kulkarni, Hani Babiker, Debabrata Mukhopadhyay, Santanu Bhattacharya. Tumor treating fields (TTFields) alter nanomechanical attributes of cell-ECM complex in pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 5105.

Abstract Background: TTFields are non-invasive and novel treatment modality that utilizes low intensity, alternating, and intermediate frequency electrical fields to inhibit cancer cell proliferation through a multitude of mechanisms. These include inhibition of mitosis, disruption of cancer cell membranes, metabolomic dysregulation of cancer cells, and immunogenic activation of the tumor microenvironment (TME). TTFields are approved in glioblastoma multiforme, non-small cell lung cancer and malignant mesothelioma. The PANOVA2 trial demonstrated promising efficacy for TTFields when applied together with chemotherapy in patients with PDAC. Mechanisms of TTFields in PDAC need further delineation. We sought to investigate the efficacy of TTFields in vitro and in vivo in PDAC cell lines and mouse models. Preclinical studies were conducted in concert with an going clinical trial (NCT04605913). Experimental Procedures: Utilizing the inovitro apparatus we studied the effect of TTFields (150kHz, intensity 2.9+0.2 V cm RMS, 37ċ, over 72 hrs) in an array of PDAC (Panc1, KPC, Panc2, and AsPC1) and human pancreatic stellate cells (hPSC) cell lines, alone or together with cisplatin (Cis, 0.1μM) or gemcitabine (Gem, 0.01μM), compared to control. Cell viability analysis was conducted in each of the groups. In addition, cell lysates from Panc1 cells from concomitant treatment of TTFields plus Gem were probed for STAT3 and α-SMA to analyze stromal proteins and RAS pathway components (KRAS, P38, P42, and others) were performed via Westen Blot. We also performed RNA sequencing for the different groups to analyze gene expression levels. We further assessed the effect of TTFields (150kHz, intensity 1.8-2 V/cm RMS, over 2 weeks) using the inovivo system with and without chemotherapy (Cis, 0.25 mg/Kg per dose (i.p.) 3 times a week) compared to control in C57BL6 orthotopic murine models (6-7 weeks old C57BL6 mice). Summary of Results: Our analysis revealed statistically significant abrogation of PDAC cancer cell lines for the different groups and hPSC cell viability when compared to control for TTFields monotherapy (p &lt;0.001) and TTFields concomitantly with Gem or Cis (p &lt;0.0001). Western blot analysis demonstrated that TTFields alone and when combined with chemotherapy alters both the stroma and RAS pathways with confirmed downregulation of pSTAT3 and α-SMA and KRAS, P-P38, and P-P42. In vivo analysis revealed significant decrease in tumor volume and weight for the concomitant effect of TTFields + Cis. Conclusion: Our preclinical studies demonstrated the efficacy of TTFields as monotherapy and concomitantly with chemotherapy in PDAC and hPSC cell lines and mouse models. Mechanistic insights from the pre-clinical studies will inform the design of future TTFields studies in PDAC. Citation Format: Hani M. Babiker, Santanu Bhattacharya, Douaa Albelal, Shamit Kumar Dutta, Enfeng wang, Debabrata Mukhopadhyay. umor treating fields (TTFields) plus chemotherapy abrogates pancreatic ductal adenocarcinoma (PDAC) proliferation and alters the tumor microenvironment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 1834.