Actimab-B, Hematopoetic Stem Cells Transplantation:

API is collaborating with Fred Hutchinson Cancer on developing for all uses the anti-CD45 monoclonal antibody BC8 which is the backbone of Iomab-B, the advanced clinical stage drug candidate described in our clinical development section above.  The CD45 antigen is expressed on effectively all white blood cells and has significant potential, when labeled with radioisotopes, to efficiently ablate bone marrow in preparation for hematopoetic stem cell transplantation.  The utility of Iomab-B has been successfully demonstrated in clinical trials and API intends to develop the drug through approval.  However, replacing I-131 with Ac-225 would enable a much wider usage of the drug due to logistics and supply chain considerations and at the same time significantly reduce the cost of goods sold.  The antibody has already been in extensive preclinical trials labeled with bismuth 213 alpha emitter, the daughter of actinium 225 and API believes that availability of a vast body of relevant preclinical data coupled with a significant clinical experience with all the drug construct components could lead to an accelerated path into the clinic.