Trial for Waldenstrom’s Macroglobulinemia Treatment Will Continue, as Early Data Yields Promising Results


The trial of CLR 131 (iopofosine) for relapsed/refractory Waldenstrom’s macroglobulinemia will continue, as the drug will be studied in an estimated 50 patients.

The ongoing phase 2 CLOVER-1 clinical trial will continue, as an independent data monitoring committee noted promising results for CLR 131 (iopofosine) in patients with relapsed/refractory Waldenstrom’s macroglobulinemia, according to Cellectar Biosciences, the pharmaceutical company developing the drug.

“We remain highly encouraged with the consistent performance of (CLR 131) in this difficult-to-treat refractory patient population,” said James Caruso, president and chief executive officer of Cellectar, in a press release.

Waldenstrom’s macroglobulinemia is a cancer of the lymphatic system that occurs when there is a change to B cells that cause them to overproduce identical antibodies called immunoglobulins which are typically used to fight infection. However, the overproduction of these antibodies can become dangerous.

Read more: Several Factors May Impact a Waldenstrom’s Macroglobulinemia Treatment Decision

Previously published results have shown that patients with B-cell malignancies who were enrolled on CLOVER-1 tended to see improved overall response rates (the percentage of patients whose disease shrinks as a result of treatment) when given CLR 131, which gives targeted delivery of iodine-131 (a radioisotope) to the cancer cells.

Now, the plan is to enroll 50 patients with relapsed/refractory Waldenstrom’s macroglobulinemia into the trial. Participants will receive up to four doses of CLR 131 over the course of two treatment cycles.

The main goal of the study will be major response rate, which is defined as at least a 50% reduction in immunoglobulin (IgM) levels, which are antibodies that are overproduced in individuals with Waldenstrom’s macroglobulinemia, as well as duration of response and progression-free survival (how long a patient lives after treatment without their disease getting worse.)

“We have alignment with the FDA on a 20% major response rate hurdle as the primary endpoint of our pivotal study. In a poster presented at ASCO 2021, we showed an 83.3% major response rate with one complete response in six (Waldenstrom’s macroglobulinemia) patients, which served as the basis for our pursuing this indication,” Caruso said.

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