iopofosine I 131 in combination with low-dose dexamethasone

July 15, 2026: Cellectar Biosciences, Inc. (NASDAQ: CLRB) announced publication in the peer-reviewed journal Cancers of results from a Phase 1 open-label, multi-center dose-escalation study of iopofosine I 131 plus low-dose dexamethasone in 31 heavily pretreated relapsed/refractory multiple myeloma patients (median four prior lines).

Among 26 efficacy-evaluable patients, 84.6% achieved stable disease or better. Overall response rate (ORR) was 15.4% (four partial responses). In evaluable patients receiving ≥60 mCi (n=10), ORR was 30%, with activity described as more pronounced at higher total administered doses. Safety was reported as favorable/manageable, with adverse events primarily predictable and reversible cytopenias; no new safety signals and generally low-grade non-hematologic AEs.

Dose findings: maximum tolerated single dose was 31.25 mCi/m²; highest evaluated fractionated regimen was 20 mCi/m² given twice one week apart. Authors recommended a fractionated Phase 2 regimen of 15 mCi/m² on days 1 and 7 plus weekly low-dose dexamethasone, supporting continued development across B-cell malignancies.