A LAT1-specific inhibitor, JPH203 (also called KYT-0353), was developed [10] and, in preclinical studies, exerted growth inhibitory effects on xenograft tumors from various types of cancers, including biliary tract cancer (BTC) [11], colon cancer [10], T cell lymphoblastic lymphoma/T cell acute lymphoblastic leukemia [12], thymic carcinoma [13, 14], and thyroid cancer [15]. The gene discussed is SLC7A5; the disease is biliary tract cancer.