Abstract B029: CM24, a novel mAb against carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1), suppresses Neutrophil Extracellular Trap (NET)-induced migration and metastasis of cancer cells
Authors: Reuveni Hadas , David Hava Ben , Rumble Julie , Meirson Tomer , Schickler Michael 
Published: January 2023

Abstract
Background: NETs are web-like structures involved in cancer immunoediting, progression, metastatic spread and play a key role in the tumor microenvironment. NETs intensify tumor aggressiveness by enhancing cancer migration and invasion capacity and can entrap circulating cancer cells and facilitate metastasis. A better understanding of the crosstalk between cancer and NETs is crucial for the development of novel therapeutic interventions blocking cancer evasion mechanisms and preventing metastatic spread. CEACAM1, plays an important role in tumor immune evasion, metastasis, angiogenesis, and was recently suggested to be a part of the NET structure. In this study, we present for the first time the NET-related activity of CM24. We demonstrate that CM24 binds to the NET structure, significantly suppresses the NET-induced cancer cell migration and inhibits metastases in mice xenografts. Methods: CEACAM1 expression and CM24 binding in whole blood were tested by FACS and analyzed for different immune subpopulations. Expression of CEACAM1 on tumor cells and the tumor microenvironment was tested using IHC and multi-plex IF of tissue microarray (TMA). Direct binding of CM24 to NETs was tested. Primary human neutrophils were stimulated with PMA to produce NETs, fixed and stained for myeloid peroxidase (MPO), DAPI & CM24. Images were captured using confocal microscopy. CM24 effect on NET-induced migration of cancer cells was tested using a Boyden chamber chemoattractant assay in various cancer cells±NETs. In a Xenograft lung lesion model, NOD-SCID mice were IV engrafted with melanoma cells and treated with either CM24 or isotype control ±Tumor Infiltrating Immune cells (TILs). Mice were sacrificed, and lungs were removed to assess tumor burden. Results: Whole blood analysis showed that neutrophils are one of the main cell type that expresses CEACAM1 and binds CM24. CEACAM1 staining of TMAs demonstrated an enhanced expression of CEACAM1 on both the tumor cells and the TILs in the TME as compared to normal tissues. Multiplex IF staining demonstrated CEACAM1 expression on infiltrating T cells and most prominently on the myeloid cells. Direct Binding of CM24 to the NET structure was demonstrated by multiplex staining for MPO (NET marker), DAPI (DNA), and CEACAM1 and captured by confocal microscopy. We next tested the effect of CM24 on cancer cell migration with or without NETs. CM24 significantly suppressed the NET-induced migration of multiple CEACAM1 expressing cancer cells, while the isotype control had no effect. In a xenograft lung lesion model, CM24 significantly inhibited metastasis of human melanoma to the lung. A greater effect of CM24 on lung lesions was shown in the presence of TILs. Conclusions: These findings show that CEACAM1 blockade by CM24 can inhibit NET-mediated cancer cell migration in-vitro and suppress metastasis in-vivo. This novel MOA provides a rationale for the anti-metastatic activity of CM24 and may contribute to improving patient outcome. Clinical studies to evaluate CM24 efficacy are being conducted in PDAC patients.
Citation Format: Hadas Reuveni, Hava Ben David, Julie Rumble, Tomer Meirson, Michael Schickler. CM24, a novel mAb against carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1), suppresses Neutrophil Extracellular Trap (NET)-induced migration and metastasis of cancer cells [abstract]. In: Proceedings of the AACR Special Conference: Cancer Metastasis; 2022 Nov 14-17; Portland, OR. Philadelphia (PA): AACR; Cancer Res 2022;83(2 Suppl_2):Abstract nr B029.