Enzastaurin induced marked dose-dependent growth inhibition in all MM cell lines investigated including MM.1S, MM.1R, RPMI 8226 (RPMI), RPMI-Dox40 (Dox40), NCI-H929, KMS-11, OPM-2, and U266.IC50 ranged from 0.6 to 1.6 μM.
Enzastaurin has a direct effect on human tumor cells, inducing apoptosis and suppressing the proliferation of cultured tumor cells. Enzastaurin treatment also suppresses the phosphorylation of GSK3ß^ser9, ribosomal protein S6S240/244, and AKTThr³⁰⁸.
Enz inhibited PKCβ and radiosensitized HDMEC with an enhancement ratio of 1.31 ± 0.05. Enz combined with RT reduced HDMEC capillary sprouting to a greater extent than either agent alone. Enz prevented radiation-induced GSK3β phosphorylation of serine 9 while having no direct effect on VEGFR phosphorylation. Treatment of xenografts with Enz and radiation produced greater reductions in microvessel density than either treatment alone. The reduction in microvessel density corresponded with increased tumor growth delay.

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