Inhibition of autotaxin activity with <scp>IOA</scp>‐289 decreases fibrosis in mouse <scp>E0771</scp> breast tumors

Tumor-associated fibrosis contributes to an immunosuppressive microenvironment that hinders effective anti-tumor immune responses. This study investigates the potential of IOA-289, a novel autotaxin (ATX) inhibitor, which blocks lysophosphatidate (LPA) production and signaling, in modulating fibrosis in breast tumors. Bioinformatic analysis of human breast tumors revealed a strong correlation between levels of LPA_1,-4 receptors and extracellular matrix (ECM) genes. Interaction of ECM molecules and integrin β1/CD44 between myofibroblasts and other cell types had the highest contribution to cell-cell communication. We showed that LPA induced α-smooth muscle actin mRNA in mouse mammary fibroblasts and increased expressions of collagen type-I α1 chain (COL1A1) and lamininγ1. IOA-289 decreased the expressions of COL1A1, fibronectin-1, and transforming growth factor β1 (TGFβ1) in E0771 breast tumors in mice. Masson's trichrome staining revealed a marked decrease in collagen deposition within breast tumors of IOA-289-treated mice. Decreased tumor fibrosis aligns with previous findings that IOA-289 enhanced the infiltration of CD8⁺ cytotoxic T cells and decreased fibrotic factors including leukemia inhibitory factor and transforming growth factor-beta1 in tumors. We also demonstrated that E0771 cells express negligible ATX and LPA receptors. Therefore, ATX inhibition did not affect cancer cells directly in our model. These results underscore the potential of ATX inhibitors in reprogramming the tumor microenvironment to favor anti-tumor immunity and attenuate fibrosis. ATX inhibitors are in clinical trials for treating idiopathic pulmonary fibrosis and pancreatic cancer. Our results support the development of ATX inhibitors as a strategy for improving the treatment of breast cancer and other diseases involving fibrosis.