ORLANDO, FL USA (UroToday.com) - Options for immunotherapy include using the patient’s own antigen presenting cells plus a tumor antigen. A viral vector containing transgenes for tumor antigen and immunstimulatory molecules is another option. Sipuleucel-T (Provenge) is based upon a laboratory stimulated leukapheresis product from the patient. There is a 4.1-month survival benefit for OS in patients treated with Provenge. At the NCI they are focusing on off the shelf vaccines that can be widely evaluated. They are using co-stimulatory molecules, one called TRICOM, to stimulate an immune response. A phase II trial of Prosvac showed no change in progression free survival, but an improvement in OS of 8.5 months. A planned phase III trial will start this year evaluating PSA-TRICOM. One benefit in the consideration of vaccines in combination therapy is that they have little toxicity. Radiation and chemotherapy can alter tumor phenotype and sensitize them to T-cell killing. For example, in combination with samarium, PSA-TRICOM improves survival.
A final benefit, Dr. Schlom noted, was that immunotherapy is longer lasting than chemotherapy or targeted therapies.
Presented by Jeffrey Schlom, PhD at the 2011 Genitourinary Cancers Symposium, General Session III: Translational Science Session: New Targets for Prostate Cancer Therapy - February 17-19, 2011 - Orlando World Center Marriott, Orlando, Florida USA