Cellectar Biosciences (NASDAQ: CLRB) published a case study describing a complete response lasting more than eight years in a patient with diffuse large B-cell lymphoma (DLBCL) treated with a single administration of iopofosine I 131.

The case involved a 53-year-old woman with high-grade, double-hit DLBCL who had received four prior lines of therapy, including stem cell transplantation. She received a single dose of iopofosine I 131 (57.5 mCi) on March 20, 2018. The patient achieved a partial response by Day 48 and a complete response by Day 85, confirmed by both site investigators and sponsor assessment. The target lesion shrank from 825 mm³ at baseline to complete resolution by Day 85.

As of May 2026, the patient had experienced no disease progression and required no additional anticancer therapy. Duration of response, progression-free survival, and time to next treatment remain ongoing and unreached at more than eight years.

The patient experienced hematologic toxicities including anemia, lymphopenia, thrombocytopenia, and neutropenia, all of which resolved.

Cellectar said it plans to submit the findings for journal publication or presentation at a medical meeting.

James Caruso, president and chief executive officer of Cellectar, said the company is advancing a confirmatory Phase 3 study in Waldenström macroglobulinemia (WM) and expects to initiate patient dosing in the first quarter of 2027, with plans to submit an accelerated approval application to the U.S. Food and Drug Administration in the first half of 2027.

Iopofosine I 131 has been tested in Phase 2b trials for relapsed or refractory WM, multiple myeloma, and central nervous system lymphoma. The FDA has granted the drug Breakthrough designation, six Orphan Drug designations, four Rare Pediatric Drug designations, and two Fast Track designations across various cancer indications.