Progenics’ Small Molecule Therapeutic Candidate
Radiation therapy is the medical use of ionizing radiation to treat cancer by killing malignant cells. There are two forms of radiation therapy: traditional radiotherapy, also known as external beam radiation, and targeted radiotherapy.
Traditional radiotherapy involves the use of focused external radiation beams that are aimed from several angles to intersect at the location of a tumor, providing a more concentrated dose of radiation at that site of disease than in the surrounding healthy tissue. Traditional radiation therapy is often used in combination with surgery, chemotherapy and/or hormone therapy. It is estimated that between 50-60% of cancer patients undergo radiation therapy during the course of their treatment. While effective for treating the primary tumor or local spread, external beam radiation may result in damage to the surrounding healthy tissue, and frequently results, in the case of prostate cancer, in impotence (erectile dysfunction). Since it is necessarily location-specific, external beam radiation is not appropriate when the cancer has metastasized, or spread to areas of the body.
Progenics’ small molecule therapeutic candidate is designed to bind to the extracellular domain of prostate specific membrane antigen (PSMA), a protein that is expressed in >95% of prostate cancer cells, and upon binding, to be internalized by the prostate cancer cells, where its iodine-131 beta particles kill the malignant cell. The ability to specifically deliver radiation to prostate cancer cells anywhere in the body allows a commonly used therapy (radiation) to be used with precision to attack systemic disease. Preclinical data has shown high tumor uptake and a favorable tumor to kidney discrimination yielding a lethal radiation dose to the tumor while minimizing normal tissue dose. In human prostate cancer mouse models, the compound, administered in single or multiple dose schedules, significantly reduced tumor burden for a prolonged period of time and enhanced survival with no significant signs of toxicity.
We believe our candidate is a promising example of molecular medicine working to develop ever more precise therapies through targeted radiotherapeutics. Targeted radiopharmaceuticals, administered systemically to a patient, represent the potential to deliver radioactive therapy specifically to diseased cancer cells while sparing surrounding healthy tissue and organs. Targeted therapeutic radiopharmaceuticals also have the potential to deliver a variety of different radioisotopes with varying particle emission properties—enabling physicians to combine selective targeting with customized radiation depending on the size and location of the tumor.