Anti-angiogenic and anti-multiple myeloma effects of oprozomib (OPZ) alone and in combination with pomalidomide (Pom) and/or dexamethasone (Dex).

Oprozomib (OPZ or ONYX 0912) is an irreversible, orally administered proteasome inhibitor (PI) and an analog of carfilzomib. We set out to determine the anti-angiogenic effect of OPZ using the choriollantoic membrane/feather bud (CAM/FB) model and its anti-MM effects using MM xenograft models (LAGκ-1A, LAGλ-1). OPZ significantly reduced blood vessel formation, endothelial gene and protein expression using the CAM/FB assay. In vivo, we determined the anti-MM effects of OPZ, dexamethasone (Dex) and pomalidomide (Pom) and showed that the combinations of two drugs (OPZ+Dex or OPZ+Pom) showed marked anti-MM effects when compared to monotherapy. Pom+Dex and the triplicate combination (OPZ+Pom+Dex) showed more anti-MM effects when compared to the doublets of either OPZ+Dex or OPZ+Pom; continued treatment with all three drugs (OPZ+Pom+Dex) was superior when compared to Pom+Dex, in both MM xenograft models tested. These studies show that OPZ has anti-angiogenic effects, and that the combination of OPZ, Dex and Pom produces greater anti-MM effects in vivo when compared to any of the doublet combinations. These studies provide further support for clinical trials evaluating OPZ in combination with Pom and Dex.