CD38 and plasma cell myeloma: As shown in Figure 1d, tinostamustine (2.5 μM) slightly increased CD38 expression in primary myeloma cells in 3 out of 11 patients analyzed (p2134, p2071 and p2121), corresponding to some of those with low basal antigen expression, but this effect was not observed in any of the patients with high CD38 basal expression.