- Zhang, Qi;
- Shi, Ce;
- Han, Lina;
- Jain, Nitin;
- Roberts, Kathryn G;
- Ma, Helen;
- Cai, Tianyu;
- Cavazos, Antonio;
- Tabe, Yoko;
- Jacamo, Rodrigo O;
- Mu, Hong;
- Zhao, Yang;
- Wang, Jing;
- Wu, Shuo-Chieh;
- Cao, Fenglin;
- Zeng, Zhihong;
- Zhou, Jin;
- Mi, Yingchang;
- Jabbour, Elias J;
- Levine, Ross;
- Tasian, Sarah K;
- Mullighan, Charles G;
- Weinstock, David M;
- Fruman, David A;
- Konopleva, Marina
Patients with cytokine receptor-like factor 2 rearranged (CRLF2-re) subgroup Philadelphia chromosome-like B-cell acute lymphoblastic leukemia (Ph-like B-ALL) have a high relapse rate and poor clinical outcomes. CRFL2-re Ph-like B-ALL is characterized by heightened activation of multiple signaling pathways, including the JAK/STAT and PI3K/AKT/mTOR pathways. We hypothesized that the combined inhibition by JAK2 and mTOR inhibitors would induce an additive antileukemia effect in CRLF2-re Ph-like B-ALL. In this study, we tested the antileukemia efficacy of the type I JAK inhibitor ruxolitinib and type II JAK inhibitor NVP-BBT594 (hereafter abbreviated BBT594) [1] alone and combined with allosteric mTOR inhibitor rapamycin and a second generation ATP-competitive mTOR kinase inhibitor AZD2014. We found that BBT594/AZD2014 combination produced robust anti-leukemic effects in Ph-like cell lines in vitro and in patient-derived xenograft (PDX) cells cultured ex vivo. JAK2/mTOR inhibition arrested the cell cycle and reduced cell survival to a greater extent in Ph-like B-ALL cells with CRLF2-re and JAK2 mutation. Synergistic cell killing was associated with the greater inhibition of JAK2 phosphorylation by BBT594 than by ruxolitinib and the greater inhibition of AKT and 4E-BP1 phosphorylation by AZD2014 than by rapamycin. In vivo, BBT594/AZD2014 co-treatment was most efficacious in reducing spleen size in three Ph-like PDX models, and markedly depleted bone marrow and spleen ALL cells in an ATF7IP-JAK2 fusion PDX. In summary, combined inhibition of JAK/STAT and mTOR pathways by next-generation inhibitors had promising antileukemia efficacy in preclinical models of CRFL2-re Ph-like B-ALL.