Dendreon (formerly Activated Cell Therapy), in association with the Mayo Clinic, is developing the dendritic cell therapy APC-8015 (Provenge) for the potential treatment of hormone-refractory prostate cancer . Phase III trials were initiated in January 2000 , and in July 2001 Dendreon anticipated that preliminary results would be available by the end of the year , . As of September 2001, Dendreon was planning tofile a BLA in 2002 . Provenge involves the use of a proprietary recombinant antigen derived from prostatic acid phosphatase, found in approximately 95% of prostate cancers. The target antigen is combined with the patient's own dendritic cells and reinfused into the patient to stimulate an immune response . In November 1999, Dendreon received US-05976546, which covers the composition of the prostate tumor antigen engineered by Dendreon to help stimulate the immune system . In August 2000, Dendreon received US-06080409, entitled 'Immunostimulatory composition', which relates to the method by which Dendreon's vaccines stimulate the T-cell arm of the immune system tofight cancer . In April 2001, Dendreon was awarded US-06210662 covering the therapeutic composition of APC-8015 .