Clinical trials test radioimmunotherapy to treat PCa bone mets.
Prostate cancer is one of the most common forms of bone mets (spread to the bone), along with breast and lung cancer. However, prostate cancer (PCa) has a unique property that allows a new form of targeted tumor destruction called radioimmunotherapy (radiation + an immune system component). What makes PCa so unique is a very high concentration of a surface protein called PSMA (prostate-specific membrane antigen) on PCa cells. In fact, it is estimated that PSMA is 1000 times more concentrated on each cancer cell than on a healthy prostate tissue cell.
Scientists have found a way to take advantage of PSMA and turn it into an entry point through which radioactive particles can be delivered into each tumor cell and cause it to die off. The radioactive particles are called Lutetium 177, or Lu-177. These particles can be “attached” to components of the immune system called monoclonal antibodies that can be specially engineered to bind with PSMA. When injected into the bloodstream, the “loaded” antibodies travel throughout the body and locate the dense PSMA on bone tumors. Like a key unlocking a door, PSMA allows the antibody into the cell where it delivers its lethal load. Lu-177 works well because its radioactivity doesn’t scatter far enough to harm nearby healthy structures, its radiation lingers long enough to damage the PCa’s DNA so it can’t reproduce, and Lu-177 can be picked up on imaging to confirm it reached its target. Although there have been no cases in which a complete cure has happened, clinical trials have shown that Lu-177 radioimmunotherapy reduces a patient’s PSA, appears to shrink bone tumors, and extends survival.
Researchers from Weill Cornell Medicine have published their results with Phase I and Phase II clinical trials.i They have demonstrated that the procedure is safe. Although there are some side effects from the treatment, they tend to resolve on their own or require a minimum of intervention. Radioimmunotherapy has encouraging potential as a longer term, highly targeted PCa bone mets treatment.
Science continues to search for a cure for cancer that has spread to the bone. No one knows how long it will take, but meanwhile, there are safe and effective palliative treatments to ease or prevent the pain of bone mets. In particular, the Sperling Medical Group offers MR-guided Focused Ultrasound (MRgFUS) which safely and noninvasively destroys the source of bone tumor pain. MRgFUS does not use surgery or radiation. Pain relief is rapid and durable, and usually one outpatient treatment is enough, with few reported side effects.
To find out if you or a loved one is a candidate, contact the Sperling Medical Group.
- Bone mets