Cellectar reports 12-month Phase 2b CLOVER WaM data for iopofosine I 131
Cellectar reported 12-month follow-up from the Phase 2b CLOVER WaM trial of iopofosine I 131 in relapsed or refractory Waldenström macroglobulinemia. In 55 patients, ORR was 83.6%, MRR was 61.8% and median duration of response was 17.8 months.
Cellectar Biosciences 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 Waldenström macroglobulinemia. The updated dataset includes a minimum of 12 months of follow-up for all enrolled patients, as requested by the FDA, and the company said the durability data further strengthen the previously reported efficacy results.
In the per protocol study population of 55 patients, updated 12-month data showed 83.6% ORR, 61.8% MRR and a median duration of response of 17.8 months. The company said responses deepened and remained durable during follow-up.
Patients enrolled in the CLOVER WaM clinical trial had a median of four prior lines of therapy, with a range of two to 15. Refractory rates were 77% in BTKi-exposed patients, 60% in chemotherapy-exposed patients and 58% in patients exposed to both BTKi and rituximab, which the company described as one of the most heavily pretreated and refractory WM populations studied to date.
The company also reported subset analyses from CLOVER WaM showing iopofosine I 131 demonstrated strong and consistent efficacy in both BTKi-exposed and BTKi-refractory patients. In post-BTKi patients, the company reported about 64% MRR and durable responses exceeding 18 months.
Cellectar said the FDA-requested dataset strengthens regulatory positioning for accelerated approval and supports initiation of a confirmatory trial in 4Q26. Efficacy and safety results from relapsed or refractory WM patients treated with iopofosine I 131 immediately following BTKi therapy have been accepted for presentation at the ASCO Annual Meeting taking place from May 29 to June 2, 2026 in Chicago.