Pexmetinib (ARRY-614) is a potent, orally bioavailable, dual p38 MAPK/Tie-2 inhibitor with potential antineoplastic, anti-inflammatory and antiangiogenic activities. Pexmetinib inhibited leukemic proliferation, prevented activation of downstream effector kinases and abrogated the effects of TNF-alpha on healthy hematopoietic stem cells. In ex vivo stimulated human whole blood, LPS-induced cytokines was inhibited by Pexmetinib with an IC50 value ranging from 50-120 nM. ARRY-614 inhibited the release of IL-6 from SEA- or LPS-challenged mice with an ED50 value less than 10 mg/kg. Combining Pexmetinib with lenalidomide inhibited both pro-inflammatory cytokines and tumor growth in vivo with higher potency, compared with either agent alone. In dose escalation or expansion cohorts, treatment with Pexmetinib either once daily or twice daily was applied to forty-five patients. Pexmetinib reduced the levels of circulating biomarkers and the p38 MAPK activation of bone marrow.