Recent advances in JAK3 kinase inhibitors.

The Janus family of tyrosine kinases (JAKs) has emerged as a promising target for therapeutic agents. JAKs are involved in pathways which help regulate cellular functions in the lympho-hematopoietic system critical for cell proliferation and cell survival. JAKs are abundantly expressed in primary leukemic cells from children with acute lymphoblastic leukemia (ALL) and are involved in signals regulating apoptosis. Two recently reported dimethoxyquinazoline compounds, WHI-P131 and WHI-P154 (Hughes Institute), were found to inhibit JAK3 but not JAK1 or JAK2. The high potency and selectivity of WHI-P131 for JAK3 makes it a promising candidate for new treatment strategies against ALL, the most common form of childhood cancer. In addition to its antileukemic properties, WHI-P131 also shows clinical potential for the treatment of mast cell-mediated immediate hypersensitivity reactions and allergic disorders, including asthma, as well as immunosuppression of alloimmune and autoimmune disorders.