Full Press Release Details
Durable Complete Response Achieved with Single Administration of Iopofosine I 131
Provides Additional Clinical Support for the Differentiated Mechanism of Action of Iopofosine I 131 and its Potential Utility Across a Range of B-cell Malignancies
FLORHAM PARK, N.J., Oct. 27, 2026 (GLOBE NEWSWIRE) -- Cellectar Biosciences, Inc. (NASDAQ: CLRB), a late-stage clinical biopharmaceutical company focused on the discovery and development of drugs for the treatment of cancer, today reported results from a case study highlighting a durable complete response in a heavily pretreated patient with diffuse large B-cell lymphoma (DLBCL) treated with iopofosine I 131.
The case study describes a 53-year-old woman with high-grade, double-hit DLBCL who had received four prior lines of therapy. This case demonstrates that a single administration of iopofosine I 131 produced a durable complete response lasting more than eight years in a patient with aggressive, relapsed DLBCL following multiple prior therapies and stem cell transplantation. The Company plans to submit these findings for journal publication or presentation at a medical meeting.
“This case study and results from iopofosine I 131 treatment of aggressive hematologic cancers along with the positive data generated to date in Waldenström macroglobulinemia further validate the PDC platform's ability to selectively target malignant cells,” said James Caruso, president and chief executive officer of Cellectar. “Importantly, we are now advancing our confirmatory Phase 3 study in WM and expect to initiate patient dosing in the first quarter of 2027, with plans remaining on target to submit an accelerated approval application to the U.S. Food and Drug Administration in the first half of 2027.”
The case study is particularly noteworthy because it aligns with the compelling efficacy and durability being observed in Cellectar's Phase 2b CLOVER WaM study in relapsed/refractory Waldenström macroglobulinemia (r/r WM), where iopofosine has generated durable responses in heavily pretreated patients, including patients refractory to prior therapies.
"While this case represents a single patient experience, we believe the durability and depth of response observed underscore the broader potential of iopofosine I 131 across B-cell malignancies," said Jarrod Longcor, chief operating officer of Cellectar Biosciences. "These findings reinforce the compelling clinical activity observed in our Phase 2b CLOVER WaM study, in which iopofosine I 131 delivered meaningful, durable responses in heavily pretreated patients with relapsed or refractory Waldenström macroglobulinemia, including those that were refractory to Bruton’s Tyrosine Kinase inhibitors.”
Key highlights from the case study:
Treatment and Response
• Received a single dose of iopofosine I 131 (57.5 mCi) on March 20, 2018.
• Reached a response (partial response or better) by Day 48 and achieved a complete response (CR) by Day 85 following treatment, confirmed by both site investigators and sponsor assessment.
• The target lesion shrank from 825 mm³ at baseline to complete resolution (0 mm³) by Day 85.
Durability
• As of May 2026, more than eight years after a single infusion, the patient:
• Has experienced no disease progression
• Has 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.
Safety
• The patient experienced expected hematologic toxicities, including anemia, lymphopenia, thrombocytopenia, and neutropenia, all of which resolved.
About Iopofosine I 131 Iopofosine I 131 is a novel phospholipid drug conjugate (PDC) designed to provide targeted delivery of iodine-131 directly to cancer cells. Leveraging the Company's proprietary PDC platform, iopofosine selectively accumulates in malignant cells, delivering cytotoxic radiation while limiting exposure to healthy tissues. Iopofosine I 131 has been tested in Phase 2b trials as a treatment for relapsed or refractory Waldenström Macroglobulinemia (WM), in relapsed or refractory multiple myeloma (MM) and central nervous system (CNS) lymphoma. Iopofosine I 131 has also been tested in the CLOVER-2 Phase 1b study evaluating iopofosine I 131 in pediatric patients with high-grade gliomas, for which Cellectar is eligible to receive a Pediatric Review Voucher from the FDA upon approval. The FDA has granted iopofosine I 131 Breakthrough, six Orphan Drug, four Rare Pediatric Drug and two Fast Track Designations for various cancer indications, and the EMA has granted iopofosine I 131 PRIority MEdicines (PRIME) designation.
About Cellectar Biosciences, Inc. Cellectar Biosciences is a late-stage clinical biopharmaceutical company focused on the discovery and development of proprietary drugs for the treatment of cancer, independently and through research and development collaborations. The company’s core objective is to leverage its proprietary Phospholipid Drug Conjugate™ (PDC) delivery platform to develop the next-generation of cancer cell-targeting treatments, delivering improved efficacy and better safety as a result of fewer off-target effects.
The company’s product pipeline includes iopofosine I 131, which is a PDC designed to provide targeted delivery of iodine-131 (radioisotope). Iopofosine I 131 has been tested in Phase 2b trials as a treatment for relapsed or refractory Waldenström Macroglobulinemia (WM), in relapsed or refractory multiple myeloma (MM) and central nervous system (CNS) lymphoma. The CLOVER-2 Phase 1b study is evaluating iopofosine I 131 in pediatric patients with high-grade gliomas, for which Cellectar is eligible to receive a Pediatric Review Voucher from the FDA upon approval. The FDA has granted iopofosine I 131 Breakthrough, six Orphan Drug, four Rare Pediatric Drug and two Fast Track Designations for various cancer indications, and the EMA has granted iopofosine I 131 PRIority MEdicines (PRIME) designation.
Cellectar is also developing CLR 121125 (CLR 125), an iodine-125 Auger-emitting program targeted for solid tumors, such as triple negative breast (TNBC), lung, and colorectal cancer, and is currently being evaluated in a Phase 1b study for TNBC, which will determine the recommended dose for the subsequent Phase 2 trial. CLR 125 has been well tolerated in vivo and has demonstrated strong preclinical data showing reduction or inhibition of solid tumor growth.
In addition to these assets, the Cellectar team is developing CLR 121225 (CLR 225), an actinium-225 based program targeting solid tumors in indications with significant unmet need, such as pancreatic cancer, as well as proprietary preclinical PDC chemotherapeutic programs and multiple partnered PDC assets.
For more information, please visit https://www.cellectar.com/or join the conversation by liking and following us on the company’s social media channels: X, LinkedIn, and Facebook.
Forward Looking Statements This news release contains forward-looking statements. You can identify these statements by our use of words such as "may," "expect," "believe," "anticipate," "intend," "could," "estimate," "continue," "plans," or their negatives or cognates. These statements are only estimates and predictions and are subject to known and unknown risks and uncertainties that may cause actual future experience and results to differ materially from the statements made. These statements are based on our current beliefs and expectations as to such future outcomes. Drug discovery and development involve a high degree of risk. Factors that might cause such a material difference include, among others, uncertainties related to the FDA and EMA regulatory pathways, ability to execute strategic alternatives, identify suitable collaborators, partners, licensees or purchasers for our product candidates and, if we are able to do so, to enter into binding agreements with regard to any of the foregoing, or to raise additional capital to support our operations, or our ability to fund our operations if we are unsuccessful with any of the foregoing. A complete description of risks and uncertainties related to our business is contained in our periodic reports filed with the Securities and Exchange Commission including our Form 10-K for the year ended December 31, 2025, and our Form 10-Q for the quarterly period ending June 30, 2026. These forward-looking statements are made only as of the date hereof, and we disclaim any obligation to update any such forward-looking statements.