Initial findings from this CLOVER-1 expansion cohort of quad-class refractory (including anti-BCMA immunotherapy) R/RMM patients adds to the body of evidence that fractionated dosing achieving ≥60 mCi total body dose of iopofosine can be safely administered, leading to an ORR of 50%, with stable disease or better for all treated patients. The depth and durability of response to iopofosine in this heavily pretreated, refractory population compares favorably with previous experience with iopofosine and other treatments being used alone in similar patient populations. One limitation of this primary analysis was its small patient cohort and the short duration of follow-up. Continued patient enrollment in this cohort as well as a longer follow-up is needed.