Dr. Neeraj Agarwal on PROSTVAC and Other Immunotherapies in Prostate Cancer

Neeraj Agarwal, MD associate professor in the Division of Oncology, Department of Medicine, director of the Genitourinary Medical Oncology Program, Huntsman Cancer Institute at the University of Utah, discusses the pox viral vaccine rilimogene galvacirepvec/rilimogene glafolivec (PROSTVAC) and the future of immunotherapy in prostate cancer.

The BNIT-PRV-301 study is evaluating the efficacy of PROSTVAC with or without granulocyte-macrophage colony-stimulating factor (GM-CSF) in patients with asymptomatic or minimally symptomatic metastatic castration-resistant prostate cancer. The primary endpoint of the trial is overall survival (OS).

PROSTVAC is an immunotherapy that uses 2 kinds of pox viruses—vaccinia virus and fowl pox virus—which are genetically engineered to express PSA transgene and trickles to molecules of T cells.

A previously conducted phase II trial yielded very encouraging data, says Agarwal, demonstrating an improvement in OS by approximately 8 months. Updated data showed that the median OS benefit with PROSTVAC immunotherapy is now 10 months, he says.

A phase III trial has been conducted and has completed accrual as well.

Checkpoint inhibitors, such as ipilimumab, nivolumab (Opdivo), or pembrolizumab (Keytruda), are also being investigated in the metastatic prostate cancer setting. While they have not shown much success as single agents, combinations of these therapies may be more valuable in the future and may yield higher response rates, says Agarwal.

There are many trials currently ongoing which are using various combinations of these immunotherapies, such as PROSTVAC with ipilimumab, ipilimumab with nivolumab, and checkpoint inhibitors with targeted drugs. The future looks good and is very promising, says Agarwal.