RGX-104 HCl is primarily investigated for its role in cancer immunotherapy. It functions as a small molecule agonist of the liver X receptor (LXR), which plays a key role in modulating the immune system within the tumor microenvironment. By activating LXR, RGX-104 HCl helps reduce immunosuppressive cells such as myeloid-derived suppressor cells (MDSCs) and regulatory T cells (Tregs), thereby enhancing the body’s anti-tumor immune response. It has shown potential in combination with other immunotherapies, such as immune checkpoint inhibitors (e.g., anti-PD-1 antibodies), to improve treatment outcomes in solid tumors and hematologic malignancies. Preclinical and early clinical studies suggest activity in cancers including melanoma, lung cancer, and ovarian cancer. Its ability to reprogram the tumor microenvironment makes it a promising candidate for overcoming resistance to existing immunotherapies.