The present invention provides compounds of Formula I:or pharmaceutically acceptable salts thereof, as well as their compositions and methods of use, that inhibit the activity of Janus kinase (JAK) and are useful in the treatment of diseases related to the activity of JAK including, for example, inflammatory disorders, autoimmune disorders, cancer, and other diseases.本發明提供式I化合物:或其醫藥學上可接受之鹽,以及其組成物及使用方法,其抑制Janus激酶(JAK)之活性且可用於治療與JAK活性有關之疾病,包括例如發炎性病症、自體免疫病症、癌症及其他疾病。