Imaging Agent with CT Scans Aids Brachytherapy

Researchers combined a radio-labeled monoclonal antibody with computed tomography (CT) scans to locate the highest areas of tumor burden in the prostate and then implanted radioactive seeds within those areas. The study was conducted by researchers from the University Hospitals of Cleveland (OH, USDA) and published in the International Journal of Radiation Oncology.

The radio-labeled monoclonal antibody is called ProstaScint, developed by Cytogen Corp. (Princeton, NJ, USA; www.cytogen.com). ProstaScint is currently used to help doctors determine whether prostate cancer has spread beyond the prostate gland. In the current study, ProstaScint's ability to bind a proprietary cancer marker (prostate-specific membrane antigen, or PSMA) on prostate cancer cells enabled doctors to deliver higher doses of radiation to regions with a higher tumor burden while sparing more-sensitive structures such as the urethra, rectum, and bladder.

Current diagnostic technologies such as magnetic resonance imaging (MRI) or CT only provide anatomical information and do not offer insight into the biology of cancer, said Rodney J. Ellis, M.D., director of brachytherapy at the University Hospitals of Cleveland and lead author of the study. Biological imaging will radically change current concepts in oncology.

Recently, Cytogen made an agreement with Draxis Health, Inc. (Toronto, Canada) to market and distribute Brachyseed implants for prostate cancer therapy. The implants are robotically manufactured by Draxis and may offer improved dosimetry and better patient safety, says Cytogen. The company is developing in-vivo immunotherapies for prostate cancer, including cancer vaccines and monoclonal antibody-based therapies.