How ProscaVax works
A hallmark of prostate cancer is high levels of the protein prostate-specific antigen (PSA) that the cancer produces.
ProscaVax is a cancer vaccine whose aim is to teach the immune system to identify PSA as a target and attack the cancer cells.
The vaccine contains PSA protein and two factors designed to activate and rev up an immune response: interleukin-2 (IL-2) and granulocyte-macrophage colony-stimulating factor (GM-CSF). IL-2 and GM-CSF stimulate the production of immune cells.
Certain immune cells are able to make immune T-cells aware of antigens, or proteins that are not normally found in the body. This prompts cell-killing T-cells to attack the cells containing a particular antigen.
ProscaVax is designed to stimulate the production of T-cells that target PSA, decreasing a prostate cancer tumor.
ProscaVax in clinical trials
ProscaVax is being investigated in an ongoing open-label Phase 1 clinical trial (NCT02058680) sponsored by OncBioMune. The company is collaborating with the U.S Department of Defense and the University of California San Diego School of Medicine on the study.
The trial is assessing the safety and effectiveness of ProscaVax, The effectiveness yardsticks include patients’ overall survival, whether the cancer recurs, patients’ PSA levels, and the level of the immune response that the therapy generates. The study is also measuring participants’ ability to tolerate the drug.
Researchers originally intended to enroll 48 patients who had prostate cancer associated with increasing PSA levels and who had failed to respond to other therapies. After favorable interim safety results, OncBioMune reduced the number of participants to 20. The study is expected to be completed by December 2018. The company also plans a Phase 2 trial with a 120 participants.
Interim results of the Phase 1 trial indicate that ProscaVax may benefit prostate cancer patients. Of the 20 patients enrolled, four dropped out of the study because their disease progressed. Of the 16 remaining, 14 have received all six of the vaccinations that researchers planned, so they were included in the interim analysis.
The rate of PSA increase in nine patients’ blood dropped during the median follow-up time of 31 months, suggesting slower tumor growth. That was 64 percent of the 14. In addition, 12 of the 15 patients analyzed so far — or 80 percent — have mounted an immune response to PSA.
OncBioMune has submitted an application to the U.S. Food and Drug Administration to start the Phase 2 trial of ProscaVax. OncBioMune has also began enrolling prostate cancer patients in a Phase 2/3 trial in Mexico.
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