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Prostate Vaccine Succeeds in Phase I Trial

by Lynn Shapiro, Writer | June 09, 2009
Antigen Express is working
on active immunotherapy
Antigen Express, a subsidiary of biotech firm Generex, told an American Society of Clinical Oncology meeting last week that its prostate cancer vaccine had proved successful in Phase I clinical trials in 29 men with various stages of prostate cancer.

"While Phase I trials are focused on safety, we took blood from patients and found that we got the immunological response that we wanted," Anitigen's president, Eric von Hofe, PhD, told DOTmed News.

"We also saw a decrease in PSA levels in some patients but as this is a Phase I trial, this evidence is preliminary," Dr. von Hofe said.

Antigen's compound, dubbed AE37, is actually a portion of the HER-2/neu protein that immune cells--specifically CD4 cells--are capable of recognizing, Dr. von Hofe says. He calls CD4 cells the "generals" of the immune system.

"Antigen's technology involves taking a fragment of the Her-2 protein in a critical region that immune cells recognize, and modifying it so that it more potently stimulates CD4 cells to fight cancer," he says.

Speaking about cancer vaccines' long road to success, Dr. von Hofe says that up until about a year ago, the field of cancer immunology was littered with failures. The first vaccine to show promise was one made by Dendrion for prostate cancer, called Provenge. The drug recently met its endpoint in Phase III clinical trials. FDA is now reviewing the drug and approval of the first cancer vaccine could be imminent.

"I'm personally convinced that active immunotherapy in cancer will be a significant weapon in oncologists' arsenal for fighting cancer in five to 10 years," Dr. von Hofe tells DOTmed.

Breast Cancer Trial

He also says Antigen's vaccine is in Phase II trials for breast cancer patients, whose tumors over-express the HER-2/neu protein.

He notes that Genentech's blockbuster drug, Herceptin--which also zeroes in on cancer that is over-expressing HER-2/neu--can be used only in patients expressing the highest level of HER-2, or about 25 percent of breast cancer patients. In comparison, Antigen's vaccine stimulates the immune system to recognize tumor cells in patients with a lower expression of HER-2, so that 75 percent of breast cancer patients would respond to Antigen's vaccine.

"We also believe that there could be a synergistic response if we use Herceptin with an immunological drug like AE37, but we haven't tried that yet," Dr. von Hofe says. "We're focused more on looking at AE37 alone."

He notes that Herception sales in 2008 were $1.8 billion, so the potential market for Antigen's vaccine would be even larger.