Leonard G. Gomella, MD, Bernard W. Godwin Jr. professor of prostate cancer and chairman of the Department of Urology, director of Clinical Affairs, Jefferson Kimmel Cancer Center, discusses the phase II NeoACT (NEOadjuvant Active Cellular immunoTherapy) sipuleucel-T study that was presented at the American Society of Clinical Oncology Genitourinary Cancers Symposium (ASCO-GU), held on February 2-4, 2012, in San Francisco, California.

The NeoACT study was conducted as a proof of principle study and evaluated the addition of sipuleucel-T prior to radical prostatectomy in 42 patients with localized prostate cancer. The goal of the study was to determine the efficacy of sipuleucel-T by analyzing potential prognostic markers.

The study demonstrated immune response through the upregulation of CD54, a marker for antigen presenting cell activation. Other T-cell activation markers were observed, which allowed investigators to gauge the immune response elicited by sipuleucel-T.

Gomella notes that immunotherapy is challenging because there is not currently a marker for response. Patients that are asymptomatic or minimally symptomatic demonstrate improved survival after receiving sipuleucel-T, but a marker is not available that shows which patients benefit the most. Currently used tests, such as PSA, do not work well in this setting and cannot be used to determine immunotherapy efficacy.

Sipuleucel-T is currently approved to treat only advanced types of prostate cancer. The ability to activate and gauge an immune response provides the potential to conduct trials in early-stage cancer, which could limit early recurrences and potentially help treat localized prostate cancer.