HDAC6 and hilar cholangiocarcinoma: ■Pyrimidinecarboxylic acid;■Investigational for breast carcinoma (phase 1), chronic lymphocytic leukemia (phase 1), diabetic neuropathy (phase 2), multiple myeloma (phase 1), peripheral nervous system disease (phase 1), hilar cholangiocarcinoma (phase 1), and lymphoma (phase 1);■Histone deacetylase 6 (HDAC6) inhibitor.