Mukhopadhyay, Debabrata

Summary Functional ex vivo assays using live tumor tissues have demonstrated strong predictive accuracy for response to immune checkpoint inhibitors (ICIs) but are not scalable, requiring manual processing of large resections collected at academic centers. Here, an ex vivo live tumor fragment (LTF) platform was developed using standard-of-care biopsies from 228 patients with suspected malignancy collected across prospective, multicenter observational trials and biobanks. Hierarchical clustering of ICI-mediated changes in cytokine production identified two groups: responders and nonresponders. A binary classifier (elive index) using 8 cytokines achieved an AUC of 0.99 for cluster prediction. elive index correctly predicted clinical benefit in 93% (26/28) of patients ( P = 3.2x10 -5 ) and accurately identified 83% (10/12) of objective responders. Critically, elive responders were identified among biomarker-negative patients, highlighting the platform as a scalable approach that complements existing companion diagnostics and expands the population of patients identified to benefit from ICI therapy.

Introduction Recent transcriptome analysis has demonstrated increased expression of Vascular Endothelial Growth Factor receptor-1 (VEGFR-1/FLT1) and in AD brain. Increased expression of VEGFR1 and its ligand VEGFB were associated with a more rapid rate of cognitive decline, providing evidence of a potential link between increased VEGFR-1 expression in AD pathogenesis. In this study, we explored the potential role of VEGFR-1 expression in neurons on AD pathology. Methods To confirm VEGFR1 expression in AD brains, we first performed immunostaining in AD brain sections (AD - Braak stage V-VI, and normal controls - Braak 0-II). And to determine a potential detrimental role of neuronal VEGFR1 expression on AD associated pathologies, we exposed SH-SY5Y human neuroblastoma cells and mouse primary neurons to either hypoxia conditions (1%O 2 ) or 5 μ Aβ1-42 oligomers or fibrils for 24, 28 and 72hrs. Results In this study, we found preferential staining of VEGFR-1 in the neuropil and neuronal cell bodies both in AD and Control hippocampus and increased VEGFR-1 immunoreactivity in dystrophic neuritic processes in the vicinity of Thio-S positive amyloid plaques in AD brains. And treatment of SH-SY5Y human neuroblastoma cell line and mouse primary neurons, with either hypoxia conditions or Aβ1-42 oligomers, resulted in increased VEGFR-1 expression and cleaved caspase 3 activation, leading to neuronal toxicities/cell death. Similarly, treatment with Aβ1-42 fibrils also increased VEGFR-1 and cleaved caspase 3 protein levels in the SH-SY5Y cells whereas treatment with Aβ1-42 monomers had no effect on VEGFR-1 expression. In addition, we show that over-expression of VEGFR-1 intracellular domains in SH-SY5Y cells directly induced neuronal toxicities and importantly, siRNA-mediated knockdown of VEGFR-1 in neurons prevented the hypoxia, Aβ1-42 oligomer and Aβ1-42 fibril-induced toxicities and cell death phenotypes. Treatment with either hypoxia or Aβ1-42 oligomers also reduced expression of cell survival genes including VEGFR-2 and Hippo pathway YAP1 and siRNA-mediated VEGFR-1 knockdown in the neurons normalized expression of both VEGFR-2 and YAP1. Using differential gene expression analysis, we demonstrated upregulation of several inflammatory/interferon-stimulated genes (ISGs) as well as increased expression of genes involved in activation of oxidative stress and cell death pathways in response to Aβ1-42 oligomers treatment in mouse primary neurons. And siRNA-mediated VEGFR-1 knockdown in the mouse primary neurons, reduced gene expression of both the ISGs and oxidative stress/cell death pathways in response to Aβ1-42 oligomer treatment. Discussion In summary, these results show that siRNA-mediated knockdown of VEGFR-1 in neurons significantly prevented hypoxia, Aβ1-42 oligomer and Aβ1-42 fibril-induced cellular toxicities and cell death phenotypes, indicating a potential detrimental role of aberrant VEGFR-1 expression and signaling in response to AD associated pathologies.

2646 Background: Immune checkpoint inhibitors (ICIs) have transformed the management of many advanced cancers but identifying patients who are likely or unlikely to benefit from ICI treatment remains a critical challenge. Biomarkers, such as PD-L1, mismatch repair deficiency, and tumor mutational burden, capture only static, unidimensional features of the complex tumor microenvironment, and therefore inadequately predict response to immunotherapy in patients. In contrast, live tumor fragments (LTFs) preserve the full complexity of the tumor microenvironment and enable functional ex vivo assessments of ICI activity. Previous efforts have had limited clinical applicability because they required larger resection specimens often collected at a single academic center. Here, the predictive capability of an ex vivo platform using core needle and forceps biopsies from multiple clinical sites was assessed and compared to approved biomarkers. Methods: Patients with eligible solid tumors (where ICI has an indication, including renal, non-small cell lung, bladder, colorectal, and triple-negative breast cancer, and others) were enrolled in ongoing, prospective observational trials (NCT05478538, NCT05520099, NCT06349642). Biopsies were cut into LTFs, encapsulated in hydrogel, and treated sequentially with IgG antibody followed by ICI (αPD-[L]1 with or without αCTLA-4). Cytokine production was assessed by a multiplexed bead-based immunoassay at multiple time points during ex vivo treatment. Using receiver operating characteristic and precision recall analyses, we identified 9 predictive cytokines (including IFN-γ, granzyme B, and CXCL9/10), which were used to develop the Elephas score (ELP-score) to assess cytokine response to ex vivo ICI treatment. Results: Of 167 eligible patient specimens, 85% (n = 142) passed quality control metrics and 130 were used for model development. Hierarchical clustering of cytokine production revealed that 27% (n = 35) of patient specimens exhibited a cytokine response to ICI. In a validation set of 20 tumors, collected from patients who were subsequently treated with ICI, ELP-score positivity correctly identified 9 of 11 patients (82%) who had an objective response (PR/CR) to ICI, including 2 patients who were negative for FDA-approved standard-of-care ICI biomarkers. Furthermore, 5 of 5 patients (100%) with clinical progressive disease were correctly characterized as ELP-score negative. Conclusions: Using routine biopsy specimens, the ex vivo live tumor platform accurately identifies patients with clinical response to ICI therapy, including those incorrectly identified by conventional biomarkers. Ongoing efforts will test these findings in an additional validation set. If confirmed, the ex vivo LTF platform could enable the identification of patients likely to benefit from ICI therapy. Clinical trial information: NCT05478538 , NCT05520099 , NCT06349642 .

Tumor Treating Fields (TTFields) represent a novel, non-invasive therapeutic modality in oncology that employs low-intensity, intermediate-frequency alternating electric fields to disrupt mitotic processes and induce cancer cell death. This review integrates mechanistic, preclinical, and emerging clinical evidence supporting the integration of TTFields with immunotherapeutic strategies in pancreatic ductal adenocarcinoma (PDAC). Although immunotherapy has transformed the treatment landscape across multiple malignancies, its efficacy in PDAC remains limited due to the tumor’s dense stroma, immunosuppressive microenvironment, and low immunogenicity. Preclinical investigations suggest that TTFields may potentiate immune-based therapies by enhancing antigen presentation, modulating the tumor microenvironment (TME), and attenuating mechanisms of immune resistance. We highlight studies evaluating TTFields in combination with immune checkpoint inhibitors (ICI), adoptive cellular therapies, and cancer vaccines, emphasizing their potential synergistic effects in PDAC. Clinically, the phase II PANOVA-2 trial demonstrated feasibility and encouraging survival outcomes with TTFields in combination with gemcitabine and nab-paclitaxel, providing the rationale for the ongoing phase III PANOVA-3 trial and the phase II PANOVA-4 trial, which combines TTFields with chemotherapy and atezolizumab. Additional clinical experiences in glioblastoma (GBM) and non-small-cell lung cancer (NSCLC) further substantiate the broader applicability of TTFields as an immunomodulatory adjunct. Remaining challenges include optimizing treatment sequencing, identifying predictive biomarkers, and managing TTFields-associated toxicities. Collectively, current evidence positions TTFields as a promising strategy to augment immunotherapy in PDAC, warranting further translational and clinical investigation to establish its role in reshaping therapeutic paradigms.

With limited therapeutic progress despite aggressive multimodal treatment, glioblastoma (GBM) remains one of the deadliest primary brain tumors. Emerging evidence suggests that GSCs are key drivers of tumor initiation, intratumoral heterogeneity, therapeutic resistance, and recurrence. GSCs retain self-renewal capacity, multilineage differentiation potential, and remarkable plasticity, enabling them to adapt to diverse microenvironmental cues. These properties are upheld by dysregulated developmental and oncogenic signaling pathways, including Notch, Wnt/β-catenin, Hedgehog, PI3K/AKT/mTOR, and STAT3, as well as epigenetic and metabolic reprogramming. In addition, dedicated niches such as hypoxic and perivascular microenvironments critically support GSC maintenance and immune evasion. In this review, we summarize the current understanding of the molecular pathways governing GSC biology, examine their interactions with the tumor microenvironment, and discuss emerging therapeutic strategies targeting GSCs, including pathway inhibition, differentiation therapy, immunotherapy, and nanomedicine-based drug delivery. We highlight key challenges and future directions for translating GSC-targeted approaches into effective clinical interventions for GBM.

Abstract Background: Pancreatic ductal adenocarcinoma (PDAC) is driven predominantly by oncogenic KRAS signaling and characterized by an immunosuppressive, fibrotic tumor microenvironment that limits therapeutic responses. RMC-6236, a pan-KRAS inhibitor, and ONIOYID, an investigational anti-tumor agent, each demonstrate partial activity in KRAS-mutant cancers. However, their combined therapeutic potential in PDAC remains unexplored. Here, we evaluated the anti-tumor efficacy, survival benefit, and immunomodulatory effects of RMC-6236, ONIOYID and irinotecan alone and dual combinations multiple in vitro and in vivo PDAC models. Methods: In vitro cytotoxicity assays were performed using KPC, PANC-1, AsPC-1, and PANC-02 cell lines. In vivo therapeutic studies were conducted in orthotopic KPC and PANC-1 tumor models. RMC-6236 was administered orally at 10 mg/kg; ONIOYID and irinotecan was administered intravenously at 5 mg/kg. Tumor growth inhibition, survival, collagen deposition, and immune cell infiltration were analyzed. Tumor microenvironment remodeling was quantified via immunohistochemistry for CD8, CD4, collagen I, and fibronectin. Results: The combination of RMC-6236 and ONIOYID elicited potent anti-tumor effects across all evaluated PDAC cell lines, achieving greater than 90% growth inhibition in vitro. In vivo, co-treatment resulted in more than 90% tumor regression in both KPC and PANC-1 xenograft models, markedly surpassing the efficacy of individual monotherapies and other dual-agent controls. Combination therapy significantly extended overall survival and produced sustained suppression of tumor progression. Mechanistic analyses revealed a substantial reduction in collagen and fibronectin deposition within the tumor microenvironment, consistent with attenuation of desmoplasia. Immune profiling demonstrated a robust enhancement of intratumoral CD8+ and CD4+ T-cell infiltration, along with a pronounced decrease in survivin expression. Importantly, no observable systemic toxicity was detected in treated animals. Conclusions: RMC-6236 combined with ONIOYID yields synergistic anti-tumor effects, remodels the fibrotic PDAC microenvironment, enhances T-cell infiltration, and significantly improves survival in aggressive pancreatic tumor models. These findings provide strong rationale for clinical evaluation of RMC-6236-based combination therapies for KRAS driven PDAC. Citation Format: Hari Krishnareddy Rachamala, Fang Wei, Debabrata Mukhopadhyay, Hani M. Babiker. Combined KRAS pathway inhibition and ONIOYID treatment enhances tumor regression, attenuates desmoplasia, and augments T cell infiltration in pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 5842.

Abstract RMC-6236 (daraxonrasib) is a novel multiselect RAS(ON) inhibitor under investigation for pancreatic ductal adenocarcinoma (PDAC) and other RAS-mutant cancers. This compound shares structural similarities with RMC-7977 and exhibits a conserved binding site and interaction pattern within the tri-complex formed between active RAS (RAS(ON)) proteins and cyclophilin A (CypA). Tumor Treating Fields (TTFields) are low-intensity, alternating electric fields that disrupt mitosis and have shown clinical benefit in solid tumors. The PANOVA-3 trial demonstrated that TTFields combined with gemcitabine plus nab-paclitaxel improved survival, pain control, and quality of life in locally advanced PDAC. Our previous work demonstrated that TTFields abrogate oncogenic KRAS pathway. We thus hypothesize a potential for increase in effectievness with the combination. In this study, the metastatic PDAC cell line AsPC-1 was treated with TTFields (150 kHz, 1.8 V/cm), RMC-6236 (15 nM; sub-IC50), or combination. A sub-IC50 concentration (15 nM) of RMC-6236 was selected based on MTS assay results, and subsequent experiments were performed at this dose. The MTS assay revealed that both TTFields and RMC-6236 independently reduced AsPC-1 cell viability, with a more pronounced reduction observed at 72 hours compared to 48 hours. RMC-6236 alone produced minimal effects at either 48 hours (85.82 ± 13.9%) or 72 hours (90.48 ± 15.4%) compared with control (100.0 ± 8.4%, 48 h; 100.0 ± 8.2%, 72 h). TTFields treatment significantly reduced viability to 74.42 ± 21.4% at 48 hours and 50.17 ± 26.5% at 72 hours. The combination treatment (TTFields + RMC-6236) further decreased viability to 63.8 ± 25.2% at 48 hours and 40.93 ± 18.1% at 72 hours, demonstrating synergistic cytotoxicity relative to monotherapy. Clonogenic assays were performed to evaluate cell survival fractions following treatment with RMC-6236, TTFields, and their combination. Cell migration was assessed using scratch assays, revealing that untreated cells exhibited a migration rate of 91.49 ± 0.85%, RMC-6236-treated cells showed 89.48 ± 1.3%, TTFields alone reduced migration to 61.33 ± 16.3%, and combination treatment markedly suppressed migration to 24.6 ± 22.13% . For every case we were compared with 72h cell migration rate with 0 h migration rate. These findings indicate that TTFields alone significantly impair cellular motility, while their combination with RMC-6236 results in a profound anti-migratory effect, substantially inhibiting wound closure. Additionally, western blot analysis was performed to assess changes in KRAS protein expression, a key PDAC biomarker. Overall, our results demonstrate that the combination of TTFields and RMC-6236 significantly inhibits PDAC cell growth, migration, and survival at sub-IC50 concentrations, suggesting a promising alternative therapeutic approach for PDAC management. Citation Format: Ishita Saha, Santanu Bhattacharya, Debabrata Mukhopadhyay, Hani M. Babiker. Synergistic antitumor activity of tumor-treating fields and multiselect-RAS (ON) inhibitor RMC-6236 in pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 4478.

Abstract Background While immune checkpoint inhibitors (ICIs) provide durable clinical benefit in a subset of patients, current biomarkers to predict response lack accuracy. Ex vivo cytokine profiling has shown promise for improved accuracy but has been mostly limited to ICIs targeting PD-1 [Voabil et al, 2021]. This poses the question of whether ICIs beyond αPD-1 – such as CTLA4 blockade, which has been reported to act within the draining lymph node – would be amenable to similar approaches. The Elephas platform characterizes response to ICIs in live tumor fragments (LTFs) from core needle biopsies (CNBs) and resections using longitudinal cytokine profiling. Using a panel of 7 clinically relevant ICI regimens, we demonstrate cytokine responses across diverse tumor types, characterize similarities and differences in cytokine response profiles across different ICIs, and explore specimen variability in responses across ICI treatments. Methods CNBs were collected through 3 observational clinical trials (NCT05478538, NCT05520099, NCT0634962) and a biobank collection study, while resections were procured from NCI CHTN. LTFs were generated using an automated cutting device and encapsulated in hydrogel. LTFs were treated with mono (αPD-1, αPD-L1, αCTLA4, αLAG-3) or combination therapy (αPD-1/αCTLA4, αPD-1/αLAG-3, αPD-L1/αCTLA4) using a sequential treatment strategy in which isotype control followed by ICI were added to the same tissue in a single well. This approach enabled the comparison of control and treatment conditions while mitigating the effects of tumor heterogeneity. Production rates for 46 cytokines were measured using a multiplex assay. Remaining T-cell reactivity was also evaluated at the end of the assay to better understand the presence of functional T cells in LTFs. Results Unsupervised hierarchical clustering of cytokine profiling data from CNB LTFs across 129 patients identified defined responder and non-responder clusters. Within the response cluster, 4 subclusters with distinct immune phenotypes were identified. While tight clustering of samples treated with the same ICI was not observed, some enrichment of samples treated with combination ICIs was observed within individual subclusters. Further, cytokine responses to αCTLA4 monotherapy were observed, suggesting that CTLA4 blockade may act beyond the draining lymph node. LTFs from resections enabled the characterization of cytokine response profiles across treatment conditions within individual specimens, including the magnitude of cytokine response and variability in cytokine response profiles. Evaluation of T-cell reactivity provided further insight into the presence of functional T-cells in LTFs and the extent of T-cell activation achieved by ICI treatment. Conclusions This study demonstrates the platform’s ability to recapitulate diverse mechanisms of immune activation ex vivo, enabling the characterization of cytokine responses to clinically relevant ICI mono or combination therapy in live tumor tissue and supporting future efforts to improve ICI response prediction beyond αPD-1. Citation Format: Pichet Adstamongkonkul, Pierre Cunin, Santanu Bhattacharya, Tanmay Kulkarni, Amreen Nasreen, Nathan Marhefke, Nina Chen, T S. Ramasubramanian, Laura Hrycyniak, Julie Zweng, Erika von Euw, Christina Vivelo, Sean Caenepeel, Debabrata Mukhopadhyay, Hinco Gierman, Hilario Ramos. Characterization of αPD1, αPD-L1, αCTLA4, and αLAG3 as mono and combination therapy in live tumor fragments using an ex vivo cytokine profiling platform [abstract]. In: Proceedings of the AACR Immuno-Oncology Conference (AACR IO): Discovery and Innovation in Cancer Immunology: Revolutionizing Treatment through Immunotherapy; 2026 Feb 18-21; Los Angeles, CA. Philadelphia (PA): AACR; Cancer Immunol Res 2026;14(2 Suppl):Abstract nr B032.