Dose Escalation Study of I-131-CLR1404 in Patients With Relapsed or Refractory Multiple Myeloma

Multiple myeloma (MM) is an incurable, monoclonal proliferation of plasma cells. Approximately 80,000 Americans are affected by MM with approximately 22,000 new cases diagnosed and 11,000 deaths each year. The introduction of newer therapies in the past twenty years, such as autologous stem cell transplantation and novel agents such as proteasome inhibitors and immune modulating drugs has improved outcomes, with current median overall survival estimates of 3-10 years depending on a number of patient-, disease- and treatment-related factors. However, despite these innovations, myeloma relapse is inevitable. Therefore, there is a clear need for improved therapies for MM and, in particular, for relapsed disease. I-131-CLR1404 is a radioiodinated therapeutic that exploits the selective uptake and retention of phospholipid ethers (PLEs) by malignant cells. Cellectar Biosciences' novel cancer-targeted small-molecule compound (CLR1404) is radiolabeled with the isotope iodine-131 (I-131). Radioiodinated CLR1404 has been evaluated in over 60 xenograft and spontaneous (transgenic) tumor models. In all but two cases of hepatocellular carcinoma, CLR1404 demonstrated selective cancer cell uptake and retention. In various rodent tumor models, I-131-CLR1404 has also demonstrated tumor growth delay and prolongation of survival. Based on the critical unmet medical need for effective agents with novel mechanisms of action in MM, the exquisite radiosensitivity of MM, and initial preclinical and clinical experience with radioiodinated CLR1404, Cellectar Biosciences has chosen to assess I-131-CLR1404 in a MM-specific phase 1 trial.