eFT508 is a potent, highly selective, and orally bioavailable MNK1 and MNK2 inhibitor, with IC50s of 1-2 nM against both isoforms.

eFT508 reduces eIF4E phosphorylation dose-dependently at serine 209 (IC50=2-16 nM) in tumor cell lines. In a panel of appr 50 hematological cancers, eFT508 shows anti-proliferative activity against multiple DLBCL cell lines. Sensitivity to eFT508 in TMD8, OCI-Ly3 and HBL1 DLBCL cell lines is associated with dose-dependent decreases in production of pro-inflammatory cytokines including TNFα, IL-6, IL-10 and CXCL10. Further evaluation eFT508 mechanism of action demonstrates that decreased TNFα production correlates with a 2-fold decrease in TNFα mRNA half-life[1].

eFT508 shows significant anti-tumor activity in the TMD8 and HBL-1 ABC-DLBCL models, both of which harbor activating MyD88 mutations. Besides, eFT508 combines effectively with components of R-CHOP and with novel targeted agents, including ibrutinib and venetoclax, in human lymphoma models[1].

References:
[1]. Kevin R. Webster, et al. eFT508, a Potent and Selective Mitogen-Activated Protein Kinase Interacting Kinase (MNK) 1 and 2 Inhibitor, Is Efficacious in Preclinical Models of Diffuse Large B-Cell Lymphoma (DLBCL). Blood 2015 126:1554;