The ability of ISA to inhibit both the cyclase and hydrolase activities of CD38, in contrast to the more limited effect of DARA on only the cyclase activity, highlights its critical role in targeting CD38's extracellular enzymatic functions. Importantly, DARA induces significant redistribution of CD38 on the myeloma cell membrane, resulting in the release of CD38‐rich microvesicles, whereas ISA primarily remains on the cell surface or undergoes partial internalisation.63 Here, CD38 is linked to plasma cell myeloma.