AZD3965 is an investigational small molecule that targets cancer metabolism by inhibiting monocarboxylate transporter 1 (MCT1). This inhibition disrupts the transport of lactate in and out of tumor cells, which is critical for maintaining energy balance and pH regulation in cancerous tissues. By blocking lactate export, AZD3965 causes intracellular lactate accumulation, leading to metabolic stress and ultimately cancer cell death, particularly in tumors that rely heavily on glycolysis. It is being studied in clinical trials for the treatment of solid tumors and hematological malignancies, including small cell lung cancer and lymphomas. Because MCT1 is overexpressed in certain cancers and helps support tumor growth in low-oxygen environments, AZD3965 offers a targeted approach to exploit metabolic vulnerabilities in cancer cells without severely affecting normal tissues. Its development represents a novel strategy in oncology—metabolic therapy—aimed at disrupting the unique ways cancer cells generate energy and survive under stress. Combination studies with other anticancer agents, such as chemotherapy or immune checkpoint inhibitors, are also underway to enhance antitumor efficacy.