A synthetic alpha Gal (aGal) molecule, with potential immunomodulating and antineoplastic activities. Upon intratumoral injection of aGal AGI-134, aGal coats the cancer cell membranes and triggers an anti-aGal antibody-mediated immune response leading to an initial complement-dependent and antibody-dependent cellular cytotoxicity (ADCC). This cytotoxicity causes release from tumor cells and subsequent uptake of released tumor-associated antigens (TAAs) by antigen-presenting cells (APCs). This may activate a systemic immune response against the TAAs and may eradicate cancer cells. aGal is a cell-surface carbohydrate antigen not expressed by humans while being expressed by all other mammals and bacteria. Anti-aGal antibodies are continuously and abundantly produced by humans due to exposure to aGal present on intestinal bacteria in the digestive system.