Adding the immunotherapy Provenge (sipuleucel-T) to a regimen containing the oral agents Zytiga (abiraterone acetate) or Xtandi (enzalutamide) significantly extends the lives of men with metastatic castration-resistant prostate cancer (mCRPC) in a real-world setting, data from more than 6,000 Medicare patients shows.
The findings were presented in a poster titled “Overall survival (OS) among Medicare beneficiaries receiving sipuleucel-T (sip-T) versus oral treatment for metastatic castration-resistant prostate cancer (mCRPC),” at the recent American Society of Clinical Oncology (ASCO) 2020 Genitourinary Cancers Symposium in San Francisco, California.
Provenge, marketed by Dendreon Pharmaceuticals, is an immunotherapy that uses a patient’s own immune cells to fight prostate cancer. In it, a fraction of white blood cells that have been exposed to a prostate cancer protein are primed to activate the remaining immune cells to fight cancer.
Provenge is the only immunotherapy approved in the U.S. for prostate cancer that is made from a patient’s own immune cells. It was approved in 2010 based on data from the IMPACT Phase 3 trial (NCT00065442), which showed that Provenge significantly extended mCRPC patients’ lives compared to a placebo.
Since then, second-generation androgen receptor inhibitors, like Zytiga and Xtandi, not yet approved at the time of IMPACT, have become the standard care treatment for men with mCRPC. This led researchers at Dendreon to assess the benefits of Provenge when used in combination with these agents.
The researchers examined medical and pharmacy claims from 6,853 Medicare mCRPC patients who had not received any prior treatment, which means they had no treatment claims in the prior year.
Results indicated that the use of Provenge significantly extended patients’ lives from 20.7 months to 35.2 months. This 14.5-month increase in overall survival represented a 45% reduction in the risk of death.
Notably, the benefits were seen at any point during treatment, with patients receiving Provenge as part of their first-line treatment seeing the same extension in overall survival as those receiving the therapy in later lines.
At three years, nearly half (48%) of patients receiving Provenge in any line of treatment were alive, compared to 28% of those receiving Zytiga or Xtandi without Provenge.
“Based on our analysis of these real-world data, men with mCRPC who had immunotherapy added to their treatment regimen had a significant reduction in the risk of death at three years, regardless of the sequencing,” Rana R. McKay, MD, lead study author, said in a press release. McKay is a medical oncologist and assistant professor of medicine at Moores Cancer Center, University of California San Diego,
“This magnitude of risk reduction is a compelling finding, and additional analyses are underway looking at other variables that could impact outcomes,” McKay said.
Interestingly, researchers identified more than 150 variations in men’s treatment sequences in this study, highlighting the need to develop a structured approach for management of mCRPC.
“These real-world data contribute to a growing body of evidence that Provenge continues to deliver on its promise of helping men with advanced prostate cancer live longer,” said Bruce A. Brown, MD, chief medical officer at Dendreon.
Recent findings from an observational registry study — called PROCEED (NCT01306890) — also showed that men with asymptomatic or minimally symptomatic mCRPC derive the same benefits from Provenge as what had been demonstrated in IMPACT.
Men with low prostate specific antigen (PSA) levels at baseline fared particularly well, living nearly four years after receiving Provenge.
This is in line with another study also presented at the ASCO GU Cancers Symposium, demonstrating that Provenge works better in men with early-stage prostate cancer — who likely have lower PSA levels — than in those with mCRPC.
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