El-Rayes, B. F. | Search bioRxiv

bioRxiv2025

High-Dimensional Protein Analysis Uncovers Distinct Immunological and Stromal Signatures Between Primary and Metastatic Pancreatic Ductal Adenocarcinoma

Our understanding of the pancreatic ductal adenocarcinoma (PDAC) tumor microenvironment (TME) primarily stems from murine models or primary patient tumors. While metastatic tumors have generally less immune infiltration compared to primary tumors, the specific cellular features of metastatic PDAC remain understudied. This knowledge gap is impactful as most patients present with metastatic disease and are most often enrolled in clinical trials. We hypothesized PDAC tumors harbor distinct immunologic and stromal features depending on their anatomical site. Using multiplex immunohistochemistry (mIHC), spatial analysis, and single-cell mass cytometry (CyTOF), we uncover dominant immune and stromal cell populations in tumors derived from 27 primary and 26 liver metastases. Metastatic liver tumors from PDAC patients contained fewer T cells and alpha-smooth muscle actin (-SMA+) activated fibroblasts than primary lesions, while CD68+ cells were more abundant. Spatial analyses revealed distinct immune cell communities in primary and metastatic PDAC, whereby CK19+ cells clustered differentially with -SMA+, CD3+, and CD68+ cells, depending on tumor site. When comparing tumor-associated regions, the proportion of peritumoral CK19- cells remained consistent, but their composition varied by disease site. CD8+ T cells were significantly less frequent in metastatic tumors, while both CD4+ and CD8+ T cells present in primary tumors expressed more transcription factors (TFs) associated with suppressive properties, including FoxP3 and ROR{gamma}t. CyTOF revealed that T cells co-expressed multiple inhibitory checkpoint receptors, with LAG-3 and PD-1 predominating. This report reveals that primary and metastatic tumors from PDAC patients harbor vastly distinct immunologic and stromal features at the protein level. Statement of SignificanceProtein level analysis reveals distinct immunological and stromal features between primary and metastatic PDAC tumors, offering a rationale for immunotherapies that target myeloid cells and increase T cell abundance in metastatic disease.

cancer biology↗

bioRxiv2023

Novel Pan-RAS Inhibitor ADT-007 Induces Tumor Regression in Mouse Models of GI Cancer

Here, we describe a novel pan-RAS inhibitor, ADT-007, that potently inhibited the growth of RAS mutant cancer cells irrespective of the RAS mutation or isozyme. RASWT cancer cells with GTP-activated RAS from upstream mutations were equally sensitive. Conversely, RASWT cancer cells harboring downstream BRAF mutations and normal cells were essentially insensitive to ADT-007. Sensitivity of cancer cells to ADT-007 required activated RAS and dependence on RAS for proliferation, while insensitivity was attributed to metabolic deactivation by UDP-glucuronosyltransferases expressed in RASWT and normal cells but repressed in RAS mutant cancer cells. ADT-007 binds nucleotide-free RAS to block GTP activation of effector interactions and MAPK/AKT signaling, resulting in mitotic arrest and apoptosis. ADT-007 displayed unique advantages over mutant-specific KRAS and pan-KRAS inhibitors, as well as other pan-RAS inhibitors that could impact in vivo antitumor efficacy by escaping compensatory mechanisms leading to resistance. Local administration of ADT-007 showed robust antitumor activity in syngeneic immune-competent and xenogeneic immune-deficient mouse models of colorectal and pancreatic cancer. The antitumor activity of ADT-007 was associated with the suppression of MAPK signaling and activation of innate and adaptive immunity in the tumor immune microenvironment. Oral administration of ADT-007 prodrug also inhibited tumor growth, supporting further development of this novel class of pan-RAS inhibitors for RAS-driven cancers. SIGNIFICANCEADT-007 has unique pharmacological properties with distinct advantages over other RAS inhibitors by circumventing resistance and activating antitumor immunity. ADT-007 prodrugs and analogs with oral bioavailability warrant further development for RAS-driven cancers.

cancer biology↗