INmune Bio, Inc. is presenting data on the use of INB03, a dominant-negative tumor necrosis factor (TNF) inhibitor of soluble TNF (sTNF) in the treatment of high-risk MUC4 expressing HER2+ and triple negative breast cancer (TNBC). INB03 is shown to decrease T cell and macrophage immune checkpoint proteins (PD1, TIGIT, LAG3, CD47 and SIRPa) in a model immunotherapy resistant HER2+ breast cancer and decrease the metastatic potential of TNBC by downregulating cell surface markers of tumor invasion (MUC4, SNAIL and Vimectin). The two posters will be presented at the annual American Association of Cancer Research in San Diego on April 8, 2024.

The poster, titled, "INB03: a new immune checkpoint inhibitor that reprograms macrophage polarization, boosts ADCP and reverts T-cell exhaustion markers" outlines the use of human macrophages and T cells in a MUC4+HER2+ syngeneic breast cancer model to demonstrate that the combination of INB03 with an anti-HER2 antibody 4D5 has five distinct effects on the tumor biology, which results in decreased tumor growth (p. a decrease in MUC4 expression; a 3-fold increase in T cell infiltration; polarization of tumor macrophages from M1 (immunosuppressive) to M2 (anti-tumor macrophages); a doubling of antibody dependent cellular phagocytosis (ADCP) and a decrease in the expression of innate immune checkpoint proteins (CD47 and SIRP-a) and T cell checkpoint proteins (TIGIT, CTLA-4, PD1 and LAG-3). In the study, the increase in T cell infiltrate did not occur unless both anti-HER2 and INB03 immunotherapy were used in combination. Decreases in T cell and macrophage immune checkpoint proteins were caused by INB03.

All changes in immune parameters are p<0.05 unless otherwise stated. The authors concluded that INB03 enhances the M1-like phenotype and reprograms already-polarized pro-tumoral M2-like macrophages to antitumoral ones. Further, it promotes ADCP against HER2+ tumor cells by downregulating the ADCP inhibitory axis CD47-SIRPa-B7H4 in vitro.

Finally, the addition of INB03 to 4D5 treatment promotes T cell infiltration to the TME and downregulates immune checkpoint molecules and T cell exhaustion markers in vitro and in vivo. The authors speculate that these effects could avoid tumor immune evasion to anti-HER2 targeted therapies by reinvigorating the immune infiltrate. A second poster, titled, ?MUC4 is a biomarker of metastasis in TNBC and its downregulation by blocking soluble TNF prevents metastasis in combination with immunotherapy,?

studies the importance of MUC4 expression in TNBC survival. Approximately half of women with TNBC express MUC4. Overall survival of women with MUC4 expressing TNBC is dramatically worse (p<0.005) with almost a 5-fold increased risk of death (p<0.018).

MUC4 expression in the tumor negatively correlated with fewer Tumor Infiltrating Lymphocytes (TILs, p<0.003), PD-L1 (p<0.001) and Ki67 (p<0.036) expression. In human TNBC cell lines, INB03 decreased the expression mesenchymal markers of invasive capacity, MUC4, SNAIL and Vimectin, and decreased activity in an invasion assay (p<0.01). In a murine LMM3 model, treatment with the combination of INB03 and anti-PD1 checkpoint antibodies dramatically decreased lung metastasis with no animals receiving combination therapy having >3 lesions compared to 40% of control animals (p<0.05).

The authors concluded: i) MUC4 expression is an independent biomarker of poor overall survival and is associated with an increased risk of metastasis in TNBC patients; ii) MUC4 is inversely correlated with TILs, and is associated with tumors with low proliferative rate (Ki67<30%) and negative PD-L1: it would be useful to identify tumors resistant to chemotherapy and immunotherapy; iii) TNF blockade decreases MUC4 expression, mesenchymal markers and reduces invasive capacity in TNBC cell lines; iv) soluble TNF blockade in combination with anti PD-1 antibody prevents the establishment of lung metastases in a preclinical model of TNBC. They further propose soluble TNF as a new target for the treatment of TNBC, and MUC4 as a predictive marker to guide a combined treatment with selective sTNF neutralization with immunotherapy. The poster can be found on the Company?s web site.

INB03 is a DN-TNF inhibitor that neutralizes soluble TNF (sTNF) without affecting trans membrane TNF (tmTNF) or TNF receptors. Compared to currently available non-selective TNF inhibitors, INB03 preserves the immune response to cancer by decreasing immunosuppressive cells in the TME including TAM and MDSC while promoting recruitment of anti-tumor immune cells including cytolytic CD8+ lymphocytes, NK cells and anti-tumor macrophages. INB03 has completed an open label dose-escalation Phase I trial in patients with advanced cancer.

In that trial, INB03 was found to be safe and well tolerated - no dose limiting toxicity was found. INB03 decreased blood biomarkers of inflammation in patients with advanced cancer.