JAK3 and chronic recurrent multifocal osteomyelitis: Tofacitinib is a reversible inhibitor of JAK1, JAK2, JAK3 and to a lesser extent Tyrosine Kinase-2.10 In a recent review, tofacitinib has been shown to be a promising treatment option for patients with CRMO not responding to traditional therapy.11 The underlying mechanism may be by blocking JAK pathways which are used by cytokines to transmit signals such as interleukin-6.12 Other biologics that have been shown to be of benefit in patients with osteoarticular symptoms include tumor necrosis factor, interleukin-1, and interleukin-17 inhibitors.11