AZ 960 is a novel ATP competitiveJAK2inhibitor withIC50andKiof <3 nM and 0.45 nM, 3-fold selectivity of AZ960 for JAK2 over JAK3. AZ 960 inducesapoptosisand growth arrest. In vitro
AZ960 also inhibits many kinases less than 50% at a concentration of 0.1 μM such as JAK3 (IC50=9 nM), TrkA, Aurora, and ARK5. In cells, AZ 960 inhibits the phosphorylation of STAT5 in TEL-JAK2 cells with an average IC50 of 15 nM and exhibits 15-30 -fold sensitivity for TEL-JAK2-driven STAT5 phosphorylation compared with cell lines driven by other JAK kinase family members (TEL-JAK1, -JAK3, and -TYK2). AZ 960 shows potent activity in inhibiting the proliferation of the TEL-JAK2, -JAK1, -JAK3, and -Tyk2 cell lines with GI50 values of 25 nM, 230 nM, 279 nM, and 214 nM, respectively. Moreover, AZ 960 also potently inhibits SET-2 cell proliferation with an average GI50 of 33 nM by reducing both STAT3 and STAT5 phosphorylation levels. AZ 960 causes growth arrest and apoptosis of human T-cell lymphotropic virus type 1, HTLV-1pe 1, HTLV-1LV-1osis of human T-cSET-2 cell proliferation witBcl-xL by small interfering RNA potentiates anti-proliferative effects of AZ 960 in MT-1 cells. A recent study shows that AZ 960 leads to significant inhibition of the clonogenic growth and induction of apoptosis of freshly isolated AML cells from patients.
