The present invention relates to novel hydroxamic acids which are specific histone deacetylase (HDAC) inhibitors and/or TTK/Mps1 kinase inhibitors, including pharmaceutically acceptable salts thereof, which are useful for modulating HDAC and/or TTK/Mps1 kinase activity, pharmaceutical compositions comprising these compounds, and processes for their preparation.本發明係關於作為特異性組織蛋白去乙醯酶(HDAC)抑制劑及/或TTK/Mps1激酶抑制劑之新穎氧肟酸,包括其醫藥上可接受之鹽,其可用於調節HDAC及/或TTK/Mps1激酶活性,包含該等化合物之醫藥組合物及其製備方法。