Cancer Therapy: Preclinical The Janus Kinases Inhibitor AZD1480 Attenuates Growth of Small Cell Lung Cancers In Vitro and In Vivo

Purpose: The prognosis of small cell lung cancer (SCLC) is poor, and there has been very little progress in the medical treatment of SCLC in the past two decades. We investigated the potential of Janus-activated kinases (JAK) inhibitor, AZD1480, for treatment of SCLC in vitro and in vivo. ExperimentalDesign: JAK1 and JAK2were inhibited byAZD1480 or siRNAs, and the effect of inhibition of JAK gene family on SCLC cell viabilitywas evaluated. The effect of AZD1480on cell-cycle distribution and apoptosis induction was studied. Antitumor effects of AZD1480 in tumor xenografts were assessed. Results:AZD1480 significantly inhibited growth of six out of 13 SCLC cells with IC50s ranging from 0.73 to 3.08 mmol/L. Knocking down of JAK2 and JAK1 inhibited proliferation of Jak2-positive/Jak1-negative H82 cells and Jak1-positive/Jak2-negative GLC4 cells, respectively. Treatment of SCLC cells with AZD1480 for 24 hours resulted in an increase of 4NDNA content and histone 3 serine 10 phosphorylation, indicative ofG2–Mphase arrest.Moreover, SCLCsunderwent apoptosis after AZD1480 treatment as exemplifiedby the downregulation ofMCL1, the accumulation of cleaved caspase 3, cleaved PARP, and increase of annexin-V– positive cells. Finally, xenograft experiments showed that AZD1480 attenuated the growthofH82 andGLC4 tumors in mice, and we observed stronger apoptosis as well as decreased CD31-positive endothelial cells in H82 and GLC4 xenografts upon AZD1480 treatment. Conclusions: JAK inhibitor AZD1480 attenuated growth of SCLC cells in vitro and in vivo. Clinical development of anti-JAKs therapies in SCLC warrants further investigation. Clin Cancer Res; 19(24); 1–