Cellectar Biosciences, Inc. announced promising preclinical data for its proprietary novel alpha-emitting phospholipid radiotherapeutic conjugate, CLR 121225 (225Ac-CLR 121225) an actinium-labeled phospholipid ether (PLE), in pancreatic cancer models. The development of this compound will expand the company?s clinical pipeline of PLE cancer targeting compounds to include targeted alpha therapies (TATs), complementing its beta-emitting phospholipid radiotherapeutic conjugate, iopofosine I 131, which achieved its primary endpoint in the CLOVER WaM pivotal study in highly refractory Waldenstrom?s macroglobulinemia patients. Cellectar?s PLE platform may provide unique advantages which overcome the issues experienced by existing TAT delivery platforms. While current TAT platforms, such as antibodies and peptides, possess the potential to be effective for treating cancers with low tumor volume, they are challenged to treat higher volume or bulky tumors due to insufficient penetration and the need for high quantities of the target epitope.

Cellectar?s PLE?s possess biochemical properties that enable penetration of the TAT payload deep into the tumor mass and the abundance of lipid rafts on tumor cells provides near universal delivery and enhanced outcomes. In preclinical studies, CLR 121225 demonstrated potent anti-tumor activity in refractory pancreatic cancer mouse xenograft models. A single administration at each dose level (100nCi, 250nCi and 500nCi) resulted in tumor volume reduction in a dose dependent manner with the highest dose providing near complete eradication of the tumor.

Additionally, it was shown that CLR 121225 demonstrated excellent biodistribution; approximately 15 ? 20% of the infused drug accumulated in the tumor within four hours and continued to accumulate over 72 ? 96 hours.

The mice had no end organ toxicities demonstrating good tolerability. The data are consistent with experiments using other alpha emitters conjugated to the company?s proprietary PLE targeted delivery platform.