The vaccine did not cause any serious adverse events, and did not induce any dose-limiting adverse events during the first 30 days after vaccination, meeting the trial’s primary endpoint, according to the company.
ProscaVax provides immunization toward the prostate specific antigen (PSA). To do so, the vaccine contains the PSA protein, together with two immune system activators, interleukin-2 (IL-2) and granulocyte-macrophage colony-stimulating factor (GM-CSF).
Because prostate cancer cells have high levels of PSA, the approach is expected to boost the immune system response toward prostate cancer cells.
The Phase 1a part of the ongoing study (NCT02058680) enrolled 20 prostate cancer patients, who had rising PSA levels for more than six months before trial initiation. Participants received six injections of the vaccine.
The trial is being conducted at the University of California San Diego Medical School, supported by an investigational new drug status granted by the U.S. Food and Drug Administration (FDA), and with funding from the U.S. Navy Cancer Vaccine Program.
To date, four patients dropped out of the trial because their disease progressed.
At the time of analysis, 14 patients had received all six vaccinations, and followed for a median of 31 months. Nine of those patients, or 64.3 percent, increased PSA doubling time, suggesting that the ProscaVax was slowing tumor growth. Immune responses to PSA were increased in 80 percent of patients.
“These results are exactly in line with what we were expecting in the Phase 1a study, no toxicity and indications of a therapeutic benefit with ProscaVax therapy,” Jonathan Head, PhD, chief executive officer at OncBioMune, said in a press release.
“The data is supportive of both of our upcoming Phase 2 trials of ProscaVax, one in a similar patient population in Mexico and a second, first-of-its-kind trial of a therapeutic vaccine at disease presentation” said Head.
“We greatly look forward to mid-stage trials to further examine the safety and benefit of ProscaVax for so many patients in need of treatments without the well-documented, dreadful side effects of today’s therapies,” Head added.