The development of the dual Janus kinase 1/2 (JAK1/2) inhibitor ruxolitinib for the treatment of myeloproliferative neoplasms (MPNs) has led to studies of ruxolitinib in other clinical contexts, including JAK-mutated acute lymphoblastic leukemia (ALL).
Activating mutations that target JAK2, as well as JAK1, or CRLF2 and IL7RA, two cytokine receptors with which the JAKs associate in lymphoid cells, have now been identified in a subset of pediatric patients diagnosed with acute lymphoblastic leukemia (ALL), many of whom have a poor prognosis.
Somatic JAK1 mutations are found in 18% of adult precursor T acute lymphoblastic leukemias and somatic JAK3 mutations are found in 3.3% of cutaneous T cell lymphomas.
Finally, we also showed in an in vivo leukemia model that cells expressing JAK1(A634D) are hypersensitive to the antiproliferative and antitumorigenic effect of type I IFN, suggesting that type I IFNs should be considered as a potential therapy for ALL with JAK1-activating mutations.
Our findings implicate dysregulated JAK1 function in ALL, particularly of T cell origin, and point to this kinase as a target for the development of novel antileukemic drugs.