An immunotherapy for prostate cancer, which is currently used to treat men whose disease has spread to bones and is considered life threatening, shows early promise in slowing cancer progression in men whose disease has recurred following surgery, an Oregon Health & Science University Knight Cancer Institute study found.
The study results also suggest that more research is warranted to determine if the therapy, Provenge® or sipuleucel-T, could be effective in slowing the progression of the disease in its early stages.
The results of the randomized study, which were recently published in the online edition of Clinical Cancer Research, indicate that rate of rise of PSA measured in the blood was 50 percent slower in men who received the immunotherapy sipuleucel-T than those who did not. Other studies have shown that when prostate cancer returns after surgery or radiation, how rapidly PSA, a blood marker of prostate cancer, goes up correlates with the risk that the cancer will spread. It also correlates with length of life.
“One of the questions on everyone’s mind is whether sipuleucel-T could have more of an impact if it were used before the disease became life threatening. This is the first study to ask that question,” said Tomasz M. Beer, M.D., deputy director of the OHSU Knight Cancer Institute, professor of medicine in the Division of Hematology & Medical Oncology and lead author of the study. “It’s an important question for our patients because this is a drug that’s approved and available.”
Sipuleucel-T is made from a patient’s own immune cells. It is designed to stimulate a patient’s immune system to attack prostate cancer. The drug, which is manufactured by Dendreon Corp., is currently approved by the FDA to treat men with metastatic prostate cancer that is resistant to standard hormone treatment and who have minimal or no symptoms of the disease. Studies found these men live a median of four months longer when treated with the drug than those who don’t receive therapy.
But, exactly who can be helped most by the immune system boost is a subject for additional study.
“Men can live a long time with prostate cancer. If there’s a way to slow the cancer down even more at the earlier stages, the appeal is that you can change the trajectory of the disease,” Beer added. “There’s a chance of making a bigger impact.”
The study was too small to determine if the slowing in the rise of PSA will lead to delays in more serious manifestations of disease, such as spread of the cancer to bones or if it will result in longer survival. Additional larger studies are needed to answer these questions. This study, however, provides the first signal that immunotherapy may be impactful when used early after cancer recurs rather than only after the cancer is widely disseminated.
The study, titled “Randomized Trial of Autologous Cellular Immunotherapy With Sipuleucel-T in Androgen Dependent Prostate Cancer,” was funded by Dendreon. Along with Beer, the other authors are Guy T. Bernstein of the Center for Urologic Care, John M. Corman of Virginia Mason Medical Center, L. Michael Glode of the University of Colorado Health Science Center, Simon J. Hall of Mount Sinai School of Medicine, Wayne L. Poll of AKSM Clinical Research Corp., Paul F. Schellhammer of Urology of Virginia, PC/Eastern Virginia Medical School, Lori A. Jones and Yi Xu of Dendreon, Jelle W. Kylstra of Spectrum Pharmaceuticals and Mark W. Frohlich of Dendreon and PROTECT Investigators (PROvenge Treatment and Early Cancer Treatment).
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