Combined NPI-0052 and lenalidomide trigger antitumor activity in MM patient cells. (A) Purified patient MM cells (CD138⁺) were pretreated with lenalidomide for 24 hours; NPI-0052 was then added for an additional 24 hours, followed by cell death analysis using Trypan blue exclusion assay. Data are mean ± SD of triplicate samples (P < .05 for all patient samples). (B) PBMCs from healthy donors were treated (as in panel A) with indicated concentrations of NPI-0052, lenalidomide, or NPI-0052 plus lenalidomide, and then analyzed for viability using MTT assay. Data are mean ± SD (n = 3; P = .25 from Jonckheere-Terpstra test for trend).