MADISON, Wis., Dec. 01, 2016 (GLOBE NEWSWIRE) -- Cellectar Biosciences, Inc. (Nasdaq:CLRB) (the "company"), an oncology-focused, clinical stage biotechnology company, today provides a data update on the first two cohorts of the company's Phase I clinical study of CLR 131 in patients with relapsed or refractory multiple myeloma. The clinical benefit rate for this study is 80 percent despite patients receiving an average of four prior treatments, including stem cell transplant and triple drug combinations. The patients in Cohort 1 received a single 12.5 mCi/m 2 dose and patients in Cohort 2 received a single 18.75 mCi/m 2 dose. At this time, Cohort 1 and Cohort 2 patients have demonstrated post treatment median survival of 11.9 months and 4.9 months, respectively. The median survival for all evaluable patients in both cohorts continues to increase and will be followed to determine overall survival benefit. Currently, the median overall survival (mOS) for each cohort is not yet evaluable. All evaluable patients in the clinical study experienced progression free survival (PFS). In Cohort 1, patients averaged 88.5 days of PFS. While patients in Cohort 2 have already achieved an average PFS of 127 days, the average PFS in Cohort 2 continues to increase as one of the four patients is still experiencing PFS. It is important to note that overall survival of 11.9 months and PFS of 127 days in this heavily pretreated patient population is better than or equivalent to that reported by several recently approved multiple myeloma drugs. "The efficacy observed with CLR 131 at the 12.5 and 18.75 mCi/m 2 single dose compares favorably to drugs recently approved for relapsed or refractory multiple myeloma. We believe that the 18.75 mCi/m 2 dose could represent an acceptable single dose or multi-dose regimen for future studies," said Jim Caruso, president and CEO of Cellectar Biosciences. "Combined with its clean safety profile, we are optimistic regarding the potential of CLR 131 and look forward to seeing results from our recently initiated Cohort 3 at a single 25mCi/m 2 dose." An evaluation of adverse events between Cohort 1 and Cohort 2 reveal a similar profile. Patients in Cohort 1 experienced an average of 4.75 adverse events per patient while patients in Cohort 2 experienced an average of 4.25 events per patient. The median severity grade of the adverse events in both cohorts was 2.0 (mild to moderate), as graded by the National Cancer Institute's Common Terminology Criteria for Adverse Events (NCI-CTCAE). In the multi-center, open label Phase I dose escalation study, CLR 131 was administered as a single dose, 30-minute intravenous infusion on Day 1 with 40 mg dexamethasone orally weekly for 12 weeks. The primary study objective is to characterize the safety and tolerability of CLR 131 with and without dexamethasone in patients with relapsed and/or refractory multiple myeloma. Secondary study objectives include establishment of a recommended Phase II dose, both with and without dexamethasone, as well as an assessment of therapeutic activity, including progression-free survival (PFS) and additional efficacy endpoints.