Cellectar Biosciences, Inc. (NASDAQ: CLRB), a clinical-stage biopharmaceutical company focused on the discovery, development and commercialization of drugs for the treatment of cancer, today announced initial results from Cohort 6 in the Company’s ongoing Phase 1 clinical study with CLR 131 in Relapsed or Refractory Multiple Myeloma (R/R MM). The 37.5mCi/m2 fractionated dose was determined to be safe and tolerable by the independent Data Monitoring Committee (DMC). Following the determination, the Company has initiated a Cohort 7 utilizing a 40mCi/m2 fractionated dose (20mCi/m2 dose on day 1 and day 8). Data from Cohort 6 showed improved efficacy and a clear dose response compared to prior cohorts, including a 50% partial response rate, a 50% minimal response rate and 100% disease control rate. The International Myeloma Working Group defines a partial response as a 50% to 89.9% reduction in the marker of disease and minimal response as 25% to 49.9% reduction in the marker of disease. One patient achieving a minimal response with a 48% reduction in their marker is still on study and continues to be evaluated.

Cellectar Biosciences, Inc, a clinical-stage biopharmaceutical company focused on the discovery, development and commercialization of drugs for the treatment of cancer, today announced additional positive top-line results from its ongoing Phase 2 clinical study of CLR 131, the company’s lead product candidate. In the relapse refractory multiple myeloma cohort, CLR 131 achieved a 30% overall response rate in the first 10 evaluable patients. All patients reported here were administered one, single 30-minute infusion of 25mCi/m², which is approximately 25% less drug than the newly adopted fractionated dose of 15.625mCi/m² on days 1 and 8. The company previously announced an overall response rate of 33% in patients with R/R diffuse large B-cell lymphoma (DLBCL) also receiving the single, 25mCi/m² dose of CLR 131.

In the R/R multiple myeloma cohort, one patient achieved a very good partial response (a 90% or greater decrease in surrogate marker) and two had partial responses (a 50% to 89% decrease in surrogate marker) as defined by the International Myeloma Working Group. The patients in this cohort averaged five lines of systemic therapies prior to treatment with CLR 131. All patients in this cohort demonstrated at least stable disease. Cellectar continues to dose additional patients at higher fractionated doses, and the company intends to announce further data from additional cohorts later this year.