Provenge (sipuleucel-T), a treatment approved in the U.S. for metastatic castration-resistant prostate cancer, significantly increased the number of patients alive at three years, compared to a placebo, a retrospective analysis of Phase 3 clinical data shows.
The treatment, which harnesses the immune system to fight cancer, was particularly effective in African-American men, researchers report.
Those findings were presented in February at the 2019 American Society of Clinical Oncology Genitourinary (ASCO GU) Cancers Symposium, in San Francisco, in a poster titled “Interpreting survival outcomes for African-American (AA) patients (pts) with metastatic castration-resistant prostate cancer (mCRPC) treated with sipuleucel-T (SIP-T) with number needed to treat to benefit (NNTB).”
Provenge, marketed by Dendreon Pharmaceuticals, is an immunotherapy that uses a patient’s own immune cells to fight prostate cancer. It consists of a fraction of white blood cells that have been exposed to a prostate cancer protein, being primed to activate the remaining immune cells to fight cancer.
In 2010, Provenge became the first immunotherapy approved by the U.S. Food and Drug Administration for metastatic prostate cancer, after extending the lives of patients by four months, compared to a placebo.
After this approval, a Phase 4 trial called PROCEED (NCT01306890) was designed to continue studying Provenge in a real-world setting, particularly the incidence of cerebrovascular events and patient survival in the long term.
Results from this registry, it showed that the overall survival of African-American men treated with Provenge was 9.3 months longer than for Caucasian patients who received the treatment.
To confirm those findings, researchers conducted a retrospective analysis of three Phase 3 trials — D9901 (NCT00005947), D9902A (NCT01133704), and IMPACT (NCT00065442) — that examined Provenge in metastatic castration-resistant prostate cancer patients.
The studies enrolled a total of 737 patients, including 488 who had received Provenge (33 African-Americans), and 249 given a placebo.
In general, African-American men were more likely to have received prior chemotherapy, have lower hemoglobin levels, and better performance status than the remaining participants.
In the long-term, both the overall population and African-American men lived longer on Provenge than on a placebo. But, consistent with prior findings, African-American men had a greater survival benefit from the treatment.
These findings are of particular importance, especially because African-American men “tend to present with more aggressive disease and have greater than twice the mortality rate than that of Caucasian men,” Kelvin A. Moses, MD, PhD, said in a press release. Moses is lead author of the analysis and associate professor in the department of urology at Vanderbilt University Medical Center.
“The enhanced survival outcomes in African-American men should serve as a call to action for urologists and oncologists to recommend immunotherapy to all African-American patients that stand to benefit from treatment,” added Bruce A. Brown, MD, chief medical officer at Dendreon.
In two additional posters, “Experience with sipuleucel-T in metastatic castration-resistant prostate cancer (mCRPC) with visceral spread from PROCEED” and “Real-world PROCEED registry data: Sipuleucel-T in elderly men with metastatic castration-resistant prostate cancer (mCRPC),” researchers also presented new data from the PROCEED registry.
The data show that men whose disease spread to visceral organs — including liver, lung, and brain — live shorter lives than those without visceral metastasis, but still have immune activation after receiving Provenge.
In the second analysis, researchers reported that Provenge is generally well-tolerated among elderly patients.