Galectin-3 inhibition with belapectin combined with anti-OX40 therapy reprograms the tumor microenvironment to favor anti-tumor immunity

Abstract

Treatment with an agonist anti-OX40 antibody (aOX40) boosts anti-tumor immunity by providing costimulation and driving effector T cell responses. However, tumor-induced immune suppression contributes significantly to poor response rates to aOX40 therapy, thus combining aOX40 with other agents that relieve tumor-mediated immune suppression may significantly improve outcomes. Once such target is galectin-3 (Gal-3), which drives tumor-induced immunosuppression by increasing macrophage infiltration and M2 polarization, restricting TCR signaling, and inducing T cell apoptosis. A wide-variety of tumors also upregulate Gal-3, which is associated with poor prognosis. Tumor-bearing (MCA-205 sarcoma, 4T1 mammary carcinoma, TRAMP-C1 prostate adenocarcinoma) mice were treated with a Gal-3 inhibitor (belapectin; GR-MD-02), aOX40, or combination therapy and the extent of tumor growth was determined. The phenotype and function of tumor-infiltrating lymphocytes was determined by flow cytometry, multiplex cytokine assay, and multiplex immunohistochemistry. Gal-3 inhibition synergized with aOX40 to promote tumor regression and increase survival. Specifically, aOX40/belapectin therapy significantly improved survival of tumor-bearing mice through a CD8 + T cell-dependent mechanism. Combination aOX40/belapectin therapy enhanced CD8 + T cell density within the tumor and reduced the frequency and proliferation of regulatory Foxp3 + CD4 + T cells. Further, aOX40/belapectin therapy significantly reduced monocytic MDSC (M-MDSCs) and MHC-II hi macrophage populations, both of which displayed reduced arginase 1 and increased iNOS. Combination aOX40/belapectin therapy alleviated M-MDSC-specific functional suppression compared to M-MDSCs isolated from untreated tumors. Our data suggests that Gal-3 inhibition plus aOX40 therapy reduces M-MDSC-meditated immune suppression thereby increasing CD8 + T cell recruitment leading to increased tumor regression and survival.

Galectins in Cancer and the Microenvironment: Functional Roles, Therapeutic Developments, and Perspectives

“…The interactions of extracellular Gal not only activate downstream cell signaling pathways but also contribute to environmental reprogramming ( Figure 6 ). For example, increased Gal-3 levels are often detected in cancer patients’ blood, indicating that circulating Gal contributes to microenvironment reprogramming during cancer progression [ 75 , 138 ]. Circulating Gal-3 interacts with endothelial cells, which induce cytokine production that promotes cancer progression [ 139 , 140 ].…”

Galectins in Glioma: Current Roles in Cancer Progression and Future Directions for Improving Treatment

“…However, overall, all of these immune-related functions have provided the rationale for testing whether Gal-3 can potentiate the effect of ICIs. A recent study using belapectin, a polysaccharide polymer that contains galactose and other sugars, has reported that this drug can potentiate the effect of ICIs and anti-OX-40 agonists in preclinical studies of multiple cancer models [ 80 , 81 , 82 ]. Notably, a recent in silico analysis by Takashima and colleagues showed that the genes encoding Gal-3 and Gal-9 were among the top 20 immunotherapy-related genes whose expression was significantly modulated.…”

“…It is noteworthy to mention that although the affinity of carbohydrate-based inhibitors is generally in the micromolar range, which is often considered low for an inhibitor, they have proven to be very effective in inhibiting the function of galectins in vitro and in vivo. A case in point is the in vivo effect of belapectin [ 80 , 81 , 82 ]. Another example is the recently described monosaccharide galactose-based antagonist of human Gal-8.…”

Cell-Intrinsic and Extrinsic Effects of Galectin-1 and Galectin-3 in B-Cell Precursor Acute Lymphoblastic Leukemia

“…We used GR-MD-02 and GM-CT-01 as dual Galectin-1 / Galectin-3 inhibitors based on in vitro data reporting that the Kds of GM-CT-01 and GR-GM for Galectin-1 and Galectin-3 are similar (30). However, both compounds have been used as if they mainly inhibit extracellular Galectin-3 [GM-CT-01 ( 63)] [GR-MD-02 (64)(65)(66)(67)]. Whether this is a reasonable assumption is not clear: in vitro, GM-CT-01 does interact with Galectin-1, with a domain that does not include the classical carbohydrate-binding site (33).…”