Sipuleucel-T Demonstrates Sustained Immune Response 2 Years After Treatment in Biochemically Recurrent Prostate Cancer
Preliminary results from the phase II STAND trial have demonstrated a robust immune response with sipuleucel-T (Provenge) that continues 2 years after completing treatment in men with biochemically recurrent prostate cancer. The findings, along with data from an ongoing phase IV registry related to increasing enrollment of African Americans in prostate cancer trials, are being presented at the 2015 Genitourinary Cancers Symposium, held February 26 to 28 in Orlando.
STAND Study
The STAND study (Abstract 171) is a randomized, phase II trial that consisted of two patient study groups. One group completed sipuleucel-T 2 weeks before initiation of androgen-deprivation therapy, and the second received the drug 3 months after the start of androgen-deprivation therapy. Preliminary results from STAND indicate that immune responses were observed in both study arms and suggest there may be a greater cellular immune response in patients who received sipuleucel-T prior to androgen-deprivation therapy. Humoral immune responses were observed and similar between both treatment arms.
“It is very encouraging to observe that [sipuleucel-T] provides an immune response in men with biochemical-recurrent prostate cancer long after the course of androgen deprivation therapy has ended,” said Neal Shore, MD, Medical Director at the Carolina Urologic Research Center. “This study may also provide guidance on the optimal sequencing of immunotherapy and androgen-deprivation therapy in biochemical-recurrent prostate cancer.”
Sipuleucel-T is a personalized immunotherapy that stimulates a patient's own immune system to fight cancer. It is currently approved by the U.S. Food and Drug Administration for the treatment for asymptomatic or minimally symptomatic metastatic castrate-resistant prostate cancer.
“These are very encouraging preliminary data and the longest duration of immune responses observed following sipuleucel-T completion in men with this particular type of prostate cancer,” said Andrew S. Sandler, MD, Chief Medical Officer at Dendreon.
PROCEED Registry
In 2012, an exploratory analysis of African American patients from the sipuleucel-T phase III trials suggested a positive treatment effect in this population. Building on this observation, another abstract being presented at ASCO Genitourinary Cancers Symposium highlights successful efforts that nearly doubled enrollment of African American men in the ongoing PROCEED registry (Abstract 272).
Through tactics such as utilizing research sites in racially and ethnically diverse communities, conducting focus groups with African Americans for insight on recruitment materials and study plans, and educating research staff on enrollment goals, enrollment in this population was 11.7%, a rate comparable to the U.S. African American population, vs 5.8% in the sipuleucel-T phase III registration trials. Overall, African American men are underrepresented in randomized clinical trials for prostate cancer, yet they have the highest incidence rate for prostate cancer in the United States and are more than twice as likely as white men to die of the disease.
For full disclosures of the study authors, view the study abstracts at abstract.asco.org.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
