Direct comparison of immunomodulatory effects of established anti-MM drugs compared with didemnin B. PBMCs were isolated from a healthy donor and stimulated with IL-2 (10 ng/mL) for 24 hours. PBMCs were then cocultured with viable luc⁺ MM.1S target cells at increasing ratios of PBMCs for 4 hours in the presence or absence of Dex (A), Len (B), Bort (C), or didemnin B (D). Tumor cell viability was quantified by CS-BLI. Data were normalized to each respective drug- and PBMC-free culture of MM.1S cells (n = 4 for each condition).