Cellectar Biosciences Reports Positive 12-Month Follow-Up Data from Phase 2b CLOVER WaM Study Demonstrating Durable Responses and Efficacy of Iopofosine I 131 in r/r Waldenström Macroglobulinemia

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83.6% ORR and 61.8% MRR achieved in heavily pretreated population with median duration of response of 17.8 months FDA-requested dataset with ≥12-month follow-up on all patients strengthens regulatory positioning for accelerated approval and supports initiation of confirmatory trial in 4Q26 Compelling efficacy observed in post-BTKi patients, including ~64% MRR and durable responses exceeding 18 months Recently Announced Oversubscribed Financing of up to $140 Million with Leading Healthcare Institutional Investors Supports Confirmatory Study and NDA Filing for Accelerated Approval of Iopofosine I 131 in Waldenström Macroglobulinemia with the FDA FLORHAM PARK, N.J. , May 05, 2026 (GLOBE NEWSWIRE) -- Cellectar Biosciences, Inc. (NASDAQ: CLRB), a late-stage clinical biopharmaceutical company focused on the discovery and development of targeted oncology therapies, today announced updated and mature 12-month follow-up data from its Phase 2b CLOVER WaM clinical trial evaluating iopofosine I 131 in patients with relapsed or refractory (r/r) Waldenström macroglobulinemia (WM). The updated dataset includes a minimum of 12 months of follow-up for all enrolled patients, as requested by the U.S. Food and Drug Administration (FDA), and the durability data presented here, further strengthen the previously reported efficacy results. The Company also reports subset analyses from CLOVER WaM showing iopofosine I 131 demonstrated strong and consistent efficacy in both BTKi-exposed and BTKi-refractory patients. “The depth, durability, and consistency of responses observed across both the total population and BTKi-treated subsets underscore iopofosine’s potential as a meaningful new treatment option in WM and differentiate it from currently available therapies,” said Jarrod Longcor , chief operating officer of Cellectar Biosciences . “With the completion of at least 12-month follow-up on all patients, we believe this dataset meets key regulatory expectations for an accelerated approval submission and positions us well as we advance toward initiating our confirmatory study.” Patients enrolled in the CLOVER WaM clinical trial had a median of four prior lines of therapy (range 2-15), with refractory rates running from 77% in Bruton tyrosine kinase inhibitors (BTKi)-exposed patients to 60% in chemotherapy-exposed patients and 58% in patients exposed to both BTKi and rituximab, making this one of the most heavily pretreated and refractory WM populations studied to date. Updated 12-month data demonstrated high response rates and sustained durability, supporting its accelerated regulatory pathway and potential role as a differentiated treatment option. Summary of Efficacy Results in per Protocol Study Population (n=55): Overall Response Rate (ORR): 83.6% Major Response Rate (MRR): 61.8% (primary endpoint achieved) Median Duration of Response (DoR): 17.8 months (secondary endpoint achieved) Median Progression-Free Survival (PFS): 13.5 months Very Good Partial Response/Complete Response Rate (VGPR/CR): 14.5% Disease Control Rate (DCR): 98.2% During the follow-up period, responses deepened and remained durable, underscoring the strength of the data, especially considering that treatment with iopofosine I 131 is a fixed-dosed regimen containing four ~30-minute infusions. This further highlights its potential for meaningful clinical benefit without the need for continuous therapy. “These mature 12-month follow-up data, as required by the FDA, further strengthen the compelling clinical profile of iopofosine I 131,” said James Caruso , president and chief executive officer. “Importantly, the durability of response continues to improve over time, and the consistency of activity in post-BTKi patients reinforces the potential of iopofosine to address a critical unmet need in the second line setting and beyond. We remain committed to providing iopofosine I 131 to the thousands of patients who can benefit from treatment and plan to initiate our confirmatory study in fourth quarter of this year.” Iopofosine I 131 continues to demonstrate a predictable and manageable safety profile: Adverse events were transient and unlike other therapies approved for WM there were no significant bleeding events and low rates of infection (

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