Cellectar Biosciences Presents Compelling Efficacy Data from Phase 2b CLOVER WaM Subset Analysis of Iopofosine I 131 in Patients Relapsed/Refractory to BTK Inhibitor Therapy at the International Workshop for Waldenström Macroglobulinemia
The 24-patient subgroup had a median response duration of 16.0 months after treatment immediately following BTK inhibitors.
Sentiment and the balance of points
Rhea-AI Sentiment reads the wording of the document, how positive or negative its language is on a 1 to 5 scale. The balance of points shown with the takes weighs what the document actually discloses, so the two can disagree, for example when a trial that missed its main goal is described in upbeat language.
Rhea-AI Summary
Cellectar Biosciences (CLRB) presented Phase 2b subgroup results for iopofosine I 131 in patients with Waldenström macroglobulinemia treated immediately after BTK inhibitors.
The analysis included 24 patients from the CLOVER WaM trial’s previously reported 12-month follow-up dataset. Overall response was 87.5%, major response was 79.2% and clinical benefit was 100%. Median response duration was 16.0 months; treatment-free survival was 19.1 months. Treatment-emergent adverse events occurred in less than 10% of patients; the only Grade 3 or higher events were cytopenias, or low blood cell counts.
Cellectar expects first patient dosing in its confirmatory randomized Phase 3 trial in 1Q27, with progression-free survival as the expected primary endpoint. The company anticipates submitting an application for U.S. accelerated approval in 1H27.
How this balance works
Rhea-AI gives every point it takes from this document a weight. Minor counts 1, Moderate 3 and Major 9, so one Major point outweighs several Minor ones. The bar adds up the weights on each side, and when neither side holds more than 65% of the total the balance reads Mixed.
It reads the document as published, with the same rules for every company, and it does not look at what the market expected or at how the stock traded, so a point can be objectively good on a day the stock falls.
Rhea-AI Sentiment measures something else, the tone of the wording.
Hollow bars mark forward-looking points. How the balance works
Positive
- Moderate point. Forward-looking: it has not happened yet and may not happen.Confirmatory Phase 3 trial planning is underway; Cellectar expects first patient dosing in 1Q27.
- Moderate point. Forward-looking: it has not happened yet and may not happen.Cellectar anticipates submitting its U.S. accelerated approval application in 1H27.
- Minor pointOverall response rate reached 87.5% in the 24-patient immediate post-BTK inhibitor subgroup.
- Minor pointMajor response rate reached 79.2% in the subgroup.
- Minor pointClinical benefit rate reached 100% in the subgroup.
4 minor points
- Minor pointMedian response duration was 16.0 months.
- Minor pointTreatment-free survival was 19.1 months.
- Minor pointTreatment-emergent adverse events occurred in less than 10% of patients.
- Minor pointIopofosine I 131 has Breakthrough Therapy Designation.
Negative
- Minor pointGrade 3 or higher treatment-emergent adverse events were limited to cytopenias, or low blood cell counts.
News Explained
The disclosed response findings came from 24 patients treated immediately after a Bruton tyrosine kinase inhibitor (BTKi);
Details
Market Reaction – CLRB
On Oct 15, the day this news came out, the latest delayed price for CLRB is 1.68% below the previous close. Our momentum scanner has recorded 3 alerts for this stock so far that day. The latest delayed price is $1.16. Relative volume is exceptionally heavy at 46.1x the average.
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Key Figures
- Subgroup size
- 24 patients
- Post-BTKi CLOVER WaM subgroup
- Overall response rate
- 87.5%
- Post-BTKi subgroup
- Major response rate
- 79.2%
- Post-BTKi subgroup
- Median duration of response
- 16.0 months
- Post-BTKi subgroup
- Clinical benefit rate
- 100%
- Post-BTKi subgroup
- Treatment-emergent adverse events
- Less than 10% of patients
- Only Grade 3 or higher event was cytopenias
- First Phase 3 patient dosing
- 1Q27
- Expected timing
- Accelerated approval application
- 1H27
- U.S. application anticipated
Historical Context
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Previewed the same post-BTKi subgroup response findings before the conference presentation.
24h Move is the share-price change in the day after each event; other market factors may also have contributed.
Key Terms
progression-free survival medical
treatment emergent adverse events medical
new drug application regulatory
accelerated approval regulatory
AI-generated analysis. How Rhea-AI works. Not financial advice.
Subgroup analysis of patients who received Bruton Tyrosine Kinase inhibitor (BTKi) treatment immediately prior to iopofosine I 131 achieved
Initiation and site selections for Phase 3 confirmatory randomized clinical trial in post-first line, post-BTKi population evaluating Progression-Free Survival as primary endpoint underway; dosing of first patients expected in 1Q27 and application for U.S. accelerated market approval anticipated in 1H27
FLORHAM PARK, N.J., Oct. 15, 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 announced that efficacy results from a subset of patients treated with iopofosine I 131 immediately post-Bruton Tyrosine Kinase inhibitor (BTKi) therapy in the company’s Phase 2b CLOVER WaM clinical trial of iopofosine I 131 to treat relapsed or refractory (r/r) Waldenström macroglobulinemia (WM) were presented today at the International Workshop for Waldenström Macroglobulinemia (IWWM) taking place October 14 to October 16, 2026, in Palm Springs, California.
The poster highlighted data from a subgroup (n=24) of patients treated with a BTKi immediately prior to iopofosine I 131 from the CLOVER WaM trial in WM. This subgroup analysis is derived from the CLOVER WaM clinical trial 12-month follow-up data set previously reported.
“These compelling data further strengthen the growing body of evidence supporting the potential of iopofosine I 131 to address a critical unmet need and offers something WM patients rarely get after BTK inhibitors: deep, durable responses from a short, fixed course of treatment. Because its targeted radiation works independently of the BTK pathway and other pathways currently targeted or attempting to be targeted, we believe it has the potential to remain effective as patients become refractory to today’s targeted therapies, and those still to come,” said Jarrod Longcor, chief operating officer of Cellectar Biosciences. “Patients in the immediate post-BTKi setting often face limited treatment options and increasingly refractory disease, making the robust response rates, durable clinical benefit, and favorable tolerability profile observed in this analysis especially encouraging. With Breakthrough Therapy Designation, a mature and expanding CLOVER WaM dataset, and plans underway to dose patients in our confirmatory clinical trial in early 2027, we believe iopofosine I 131 is well positioned to become a meaningful new treatment option for these patients, and we remain focused on advancing the program toward potential regulatory approval.”
Summary of Results in Subgroup Immediately post-BTKi treatment (n=24)
The patients included in this subset analysis were enrolled in the CLOVER WaM clinical trial and were treated with iopofosine I 131 immediately after receiving a regimen containing BTKi. Seventy-five percent were BTKi refractory and more than
- Overall Response Rate (ORR):
87.5% - Major Response Rate (MRR):
79.2% - Median Duration of Response (DoR): 16.0 months
- Treatment Free Survival (TFS): 19.1 months
- Clinical Benefit Rate (CBR):
100% - Safety: Treatment emergent adverse events (TEAE) occurred in less than
10% of patients, with the only Grade 3 or higher TEAE being cytopenias
Cellectar is advancing plans to dose the first patients in the confirmatory Phase 3 randomized clinical trial in a post-first line, post-BTKi population. The registration-directed trial is expected to evaluate progression-free survival (PFS) as the primary endpoint, consistent with regulatory guidance.
The company is also preparing to submit a New Drug Application for accelerated approval with the U.S. Food and Drug Administration (FDA) in the first half of 2027, supported by the strength and maturity of the CLOVER WaM dataset.
About Accelerated Approval and Confirmatory Study Initiation
The CLOVER WaM dataset incorporates key elements aligned with regulatory expectations for accelerated approval as requested by the FDA, including:
- Use of surrogate endpoints (MRR supported by DoR) reasonably likely to predict clinical benefit
- Demonstration of durable responses in a high unmet need population
- Completion of ≥12-month follow-up across all patients
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.
INVESTORS:
Anne Marie Fields
Precision AQ
212-362-1200
annemarie.fields@precisionaq.com
FAQ
AI-generated questions and answers. How Rhea-AI works. Not financial advice.
What did Cellectar’s CLOVER WaM analysis show after BTK inhibitor treatment?
The 24-patient subgroup had an overall response rate of 87.5%, a major response rate of 79.2% and a clinical benefit rate of 100%. Median response duration was 16.0 months, and treatment-free survival was 19.1 months.
When does Cellectar expect its iopofosine I 131 Phase 3 trial and approval application?
Cellectar expects first patient dosing in the confirmatory randomized Phase 3 trial in 1Q27 and anticipates submitting its U.S. accelerated approval application in 1H27. The trial is expected to evaluate progression-free survival as its primary endpoint.
What prior treatment history did patients in Cellectar’s post-BTK inhibitor subgroup have?
Patients had a median of three prior lines of therapy, with a range of 2–7. Seventy-five percent were refractory to BTK inhibitors, meaning their disease resisted that treatment, and more than 54% had received multiple BTK inhibitor therapies. The subgroup included 17% with TP53 mutations and 29% with MYD88 wild type.