Dendreon announced new findings from a study evaluating PROVENGE (sipuleucel-T) as the first immunotherapy to generate a durable killer T-cell response that correlates with clinical benefit. The immune response was observed to PA2024, the immunizing antigen, and prostatic acid phosphatase (PAP), the target antigen on prostate tumor cells, in both men with hormone-sensitive prostate cancer and those with metastatic castrate-resistant (hormone-refractory) prostate cancer (mCRPC). Responses were observed as early as six weeks following PROVENGE treatment and persisted at a minimum for six months.i These immune responses correlated with improved overall survival (OS). These results validate Dendreon’s activated cellular immunotherapy approach of educating and activating the patient’s own immune system against prostate cancer.
The data will be presented in a poster session at the 2017 American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago. PROVENGE is the first and only cellular immunotherapy approved for use in humans.
“These findings shed new light on how PROVENGE immunotherapy extends overall survival in patients with advanced prostate cancer,” said lead study investigator Charles G. Drake, M.D., Ph.D., a nationally recognized expert in immunotherapy and director of genitourinary oncology and associate director for clinical research at the Herbert Irving Comprehensive Cancer Center at Columbia University Medical Center. “In this study, we showed for the first time that sipuleucel-T (PROVENGE), which is derived from a patient’s own white blood cells, elicits a CD8 (killer) T-cell response. These responses may help to explain the well-documented survival benefit associated with sipuleucel-T.”
“We are pleased that these data confirm the mechanism of action of PROVENGE and its effect on overall survival. This survival benefit has been demonstrated in both controlled clinical trials and in our PROCEED registry,” said James Caggiano, president of Dendreon. “PROVENGE remains the only cellular immunotherapy approved by the FDA for advanced prostate cancer and has been proven to extend life with a generally manageable safety profile. We look forward to seeing it used to help more men with advanced prostate cancer.”
Treatment with PROVENGE induces a patient’s immune system to generate a response to both PA2024 and PAP.i To assess the mechanism of action by which PROVENGE induces an immune response to both PA2024 and PAP, Dr. Drake and other investigators analyzed blood samples from 15 patients who participated in three PROVENGE clinical trials (STAND, STRIDE and STAMP).
In the pivotal Phase III trial, PROVENGE showed a statistically significant OS advantage, with an increase in median overall survival by 4.1 months and reduced the relative risk of death by 22.5 percent. The results evaluated in this study showed a sustained increase in PAP and PA2024-specific killer (CD8+) T cells responses after treatment.i This immune response was maintained through week 26.iAdditionally, OS data were available from the STAMP study, and an improved OS was shown to be strongly associated with PAP- and PA2024-specific killer T cells in patients in that study.i At 26 weeks, a strong positive correlation was observed between improved OS and PAP- and PA2024-specific memory response for killer T cells.i Patients in the STAMP trial who had a killer T-cell response above the median had markedly longer OS than patients with a response below the median, and OS was significantly longer in patients with responses above the median at week 26.
Filed Under: Drug Discovery