| The following article features coverage from the American Society of Clinical Oncology (ASCO) 2018 meeting. Click here to read more of Cancer Therapy Advisor‘s conference coverage. |
Prostvac-V/F, an investigational prostate cancer (PCa) vaccine regimen, does not improve overall survival among men with asymptomatic or minimally symptomatic metastatic castration-resistant prostate cancer (mCRPC), according to the findings of the phase 3 PROSPECT trial presented at the 2018 American Society of Clinical Oncology Annual Meeting in Chicago, Illinois.1
The latest findings failed to confirm an overall survival (OS) benefit found in a previous randomized phase 2 trial (RandPh2). In that earlier trial, median OS was significant greater among Prostvac-treated patients than placebo recipients (25.1 vs 16.6 months). Prostvac-V/F consists of a recombinant vaccinia vector as a primary vaccination, followed by 6 booster doses with a recombinant fowlpox vector.
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In the PROSPECT trial, James L. Gulley, MD, of the National Cancer Institute in Bethesda, Maryland, and colleagues, randomly assigned 1297 men from 15 countries to receive either Prostvac-V/F plus placebo, Prostvac-V/F plus GM-CSF (granulocyte-macrophage colony-stimulating factor), or placebo plus placebo. Median OS for the groups was 34.8, 33.9, and 34.7 months, respectively. The differences between the Prostvac-V/F-placebo and placebo-placebo groups and Prostvac-V/F-GM-CSF and placebo-placebo groups did not differ significantly (HR 1.02; P = .40 and HR 1.03; P = .66, respectively).
Dr Gulley’s group noted in their study abstract that the OS observed in all study arms was about 1 year longer than anticipated based on historical controls, “likely related to improved standard of care since study enrollment began in 2011.”
Adverse events of any grade occurred in 91% of patients, and 65% had injection site reactions, but only 5.8% led to premature discontinuation of treatment, according to the investigators.
The study population had a mean age of 71 years and mean PSA level of 74.5 ng/mL. Bone, lymph node, and visceral metastases were present in 74.7%, 15.7%, and 8.4% of patients, respectively.
Read more of Cancer Therapy Advisor‘s coverage of the American Society of Clinical Oncology (ASCO) 2018 meeting by visiting the conference page.
Reference
- Gulley JL, Borre M, Vogelzang NJ, et al. Results of PROSPECT: A randomized phase 3 trial of PROSTVAC-VF (PRO) in men with asymptomatic or minimally symptomatic metastatic, castration-resistant prostate cancer. J Clin Oncol. 2018: 36, (suppl; abstr 5006). Presented at 2018 ASCO Annual Meeting; June 1-5, 2018; Chicago, IL.
