Prostate Cancer Immunotherapy Treatment Can Increase Survival for Some Patients with Prostate Cancer Sipuleucel-T, the first therapeutic cancer vaccine to receive approval from the U.S. Food and Drug Administration, remains an important therapeutic option for patients with prostate cancer who have hormone-refractory metastatic disease and minimal or no symptoms, according to a UCLA urologist who participated in the clinical research leading to the drug’s approval. The drug is among a broad class of cellular agents referred to as immunotherapies, which stimulate the patient’s immune system to respond against the cancer. “Immunotherapy has become the hottest area of oncology,” says Allan Pantuck, MD, professor of urology. “The approval of sipuleucel-T — a personalized treatment that harnesses the patient’s immune cells to identify and target prostate-cancer cells — stimulated the further development of this field by showing its feasibility and effectiveness as a cancer treatment.” The drug received FDA approval in 2010 on the basis of its survival benefit for men with metastatic prostate cancer, with minimal side effects. UCLA urologists were collaborators on the clinical trials that led to the drug’s approval, and they have been treating patients with the drug since 2003. “This is not a cure, but it does seem to slow the progression of the cancer, and patients who take it live longer than those who don’t,” Dr. Pantuck says. He notes that the survival benefit averages about five months, though some patients can gain as much as a year from the treatment. The drug is for patients with castrate-resistant metastatic prostate cancer who are either asymptomatic or minimally symptomatic. “The ideal candidates have asymptomatic small-volume disease with low PSAs, although we have given it to patients who are refractory to multiple treatments,” Dr. Pantuck says. “The tolerability makes it easy to integrate into a treatment plan. We consider sipuleucel-T to be an important piece in the patient’s overall treatment strategy that may involve many different types of therapy.” two-week intervals. Patients’ immune cells are collected through a blood-drawing procedure called leukapheresis; then their cells are sent to a manufacturing facility, where they are grown in the presence of a protein that stimulates the immune cells to recognize prostate cancer. Several days after the cell-collection procedure, the patient receives a dose of sipuleucel-T. “This is a finite treatment that is given with three infusions over four weeks,” Dr. Pantuck says. “The benefit of an immune treatment is that although it is given for only one month, like other types of vaccines to prevent infections, its effect on the immune system can be durable and long-lasting.” “Immunotherapy has become the hottest area of oncology. The approval of sipuleucel-T ... stimulated the further development of this field by showing its feasibility and effectiveness as a cancer treatment.” UCLA urology researchers and clinicians have been pioneers in using immunotherapy to treat urologic cancers since the mid-1970s, and they continue to be at the forefront of developing new immunotherapies. Laboratory research by Dr. Pantuck and colleagues has led to the development of GM-CAIX, a kidney-cancer vaccine currently in a Phase I/II clinical trial. “Immunotherapy appears to be a highly promising way to go for many cancers,” Dr. Pantuck says. “It gives us a specific, individualized treatment that can recognize cancer, with fewer side effects than traditional chemotherapies.” Immature antigen presenting cells (APCs) are collected by leukapheresis and then matured by cell culture for three days in the presence of a fusion protein that includes prostatic acid phosphatase (PAP) to create a dose of sipuleucel-T. When the APCs are reinfused to the patient intravenously, they activate other immune cells to proliferate and attack prostate cancer cells expressing PAP. Illustration: Dendreon Pharmaceuticals Inc. Patient’s immature APC collection Leukapheresis Antigen presentation and APC maturation Dose created Infusion Sipuleucel-T Sipuleucel-T activates immune cells Activated immune cells attack prostate cancer Immune cells proliferate Sipuleucel-T is given to patients in three intravenous infusions administered in APC=antigen-presenting cell 3 UCLA Physicians Update