Cellectar Biosciences Soars 15.37% on FDA Breakthrough Therapy Designation

On June 5, 2025, Cellectar Biosciences, Inc. (NASDAQ:CLRB) experienced a significant surge in its stock price, rising by 15.37% in pre-market trading. This notable increase can be attributed to several key developments related to the company's innovative cancer-targeting agent, iopofosine I 131.

The U.S. Food and Drug Administration (FDA) granted Breakthrough Therapy Designation for iopofosine I 131, a novel cancer-targeting agent utilizing a phospholipid ether as a radioconjugate monotherapy. This designation is for relapsed/refractory Waldenstrom macroglobulinemia (r/r WM), a dominant subtype of lymphoplasmacytic lymphoma. The Phase 2 CLOVER WaM study presented compelling data, including an overall response rate (ORR) of 83.6% and a major response rate (MRR) of 58.2%, exceeding the agreed-upon primary endpoint of a 20% MRR. These results were highlighted during the 66th Annual American Society of Hematology Conference in December 2024.

In addition to the FDA's Breakthrough Therapy Designation, iopofosine I 131 has also received Fast Track Designation and Orphan Drug Designation from the FDA. The European Medicines Agency (EMA) has granted Orphan Drug Designation and PRIME Designation for iopofosine I 131 for WM. Cellectar has submitted a comprehensive data package to the EMA, which includes extensive preclinical, regulatory, and manufacturing data, as well as safety and efficacy data from the CLOVER WaM Phase 2b clinical trial. The EMA is currently reviewing this package to determine if there is sufficient clinical evidence for Cellectar to apply for a fast-track, conditional marketing authorization approval. A recommendation from the EMA is expected in late July 2025.