MM patients undergo a variety of regimens, resulting in a heavily pretreated yet refractory and relapsed cohort “triple-refractory disease” defined as disease refractory to prior treatment with at least one anti-CD38 antibody, a PI, and an IMiD, and “penta-refractory disease” having prior exposure to two PIs, two IMiDs, and one anti-CD38 monoclonal antibody; the latter having overall survival of fewer than six months [7]. Here, CD38 is linked to glycogen storage disease VI.