Vaccines Eyed As Prostate Cancer Treatment
By Michael Lasalandra>
Beth Israel Deaconess Medical Center Correspondent
Researchers are optimistic about a new way of treating prostate cancer that would help the body’s own immune system to attack tumors once they have developed.
One such treatment, called Provenge, is poised to be approved as the first so-called therapeutic or treatment vaccine against the disease. Researchers at a number of institutions, including Beth Israel Deaconess Medical Center, are working on others.
“We’re keeping our fingers crossed,” said Mark A. Exley, staff scientist and assistant professor at BIDMC, who is working on one such treatment vaccine.
Therapeutic or treatment vaccines are different from traditional vaccines in that they do not seek to prevent a disease but rather work to treat it once it has developed, enlisting the body’s own defense system to attack the disease. Traditional vaccines, such as Gardasil, which prevents cervical cancer, typically work against viruses.
“The big question is, will therapeutic vaccines work as well as preventative vaccines,” Exley said.
Provenge, a prostate cancer treatment vaccine developed by the Seattle biotechnology company Dendreon, prolonged the lives of men in a critical clinical trial announced in April.
In the study, Provenge extended median survival by 4.1 months, compared to placebo and improved three-year survival by 38 percent.
The study involved men with metastatic prostate cancer who were no longer responding to treatments intending to deprive their tumors of testosterone, which fuels prostate cancer.
Simo Arredouani, an instructor in surgery at BIDMC, has received awards from the Prostate Cancer Foundation and the Department of Defense for his research to develop a second generation, “off the shelf” vaccine that can be used universally. Provenge must be custom made for each patient using each patient’s own cells.
Arredouani and his collaborators, Dr. Martin Sanda, Director of the BIDMC Prostate Center, and Dr. Towia Libermann, Director of the BIDMC Genomics Core, have identified 15 proteins expressed by prostate cancer that may serve as targets for a vaccine. Two of these, known as ERG and SIM2, appear particularly promising, he said.
In studies using humanized mice -- mice that carry functioning human genes, cells or tissues -- the researchers were able to generate an immune response by injecting the vaccine -- parts of these proteins called peptides -- into the mice.
Future studies of such mice with cancer will test whether the injections actually work against the cancer itself.
“We’re hoping it will reduce the tumor size,” Arredouani said. “That will be a wonderful thing if it happens. We don’t have any choice other than to be optimistic. What we are doing is really promising.”
If the upcoming studies show the vaccine works in mice, human studies could begin within a year or two, he said.
Exley, Dr. Steven Balk and others at BIDMC are working on a complimentary approach. Funded by the Harvard Cancer Center Prostate Cancer `SPORE’ and the DOD, the research is looking at using “natural killer” T-cells (NKT) that are designed to kick-start a patient’s own immune system. These cells could be incorporated into a vaccine that already has a cancer component. These killer cells already exist in the body, but in small numbers.
This research includes using monoclonal antibodies to expand the number of NKT cells to help the body in its fight against cancer cells.
The approach has been tried successfully in mice and a trial is currently underway using it in patients with melanoma, since patients with that disease sometimes go into remission when their own immune systems are able to battle the cancer to a draw, sometimes for years, Exley said.
Studies by Exley and others of patients with advanced cancers have found they had fewer NKT cells than healthy people and also found defects in the NKT cells they did have, “as if the immune system had lost a battle,” he said.
“Our goal is to provide reinforcements to win the next battle and the war,” he added.
Above content provided by Beth Israel Deaconess Medical Center. For advice about your medical care, consult your doctor.
Posted September 2009
Beth Israel Deaconess Medical Center Correspondent
Researchers are optimistic about a new way of treating prostate cancer that would help the body’s own immune system to attack tumors once they have developed.
One such treatment, called Provenge, is poised to be approved as the first so-called therapeutic or treatment vaccine against the disease. Researchers at a number of institutions, including Beth Israel Deaconess Medical Center, are working on others.
“We’re keeping our fingers crossed,” said Mark A. Exley, staff scientist and assistant professor at BIDMC, who is working on one such treatment vaccine.
Therapeutic or treatment vaccines are different from traditional vaccines in that they do not seek to prevent a disease but rather work to treat it once it has developed, enlisting the body’s own defense system to attack the disease. Traditional vaccines, such as Gardasil, which prevents cervical cancer, typically work against viruses.
“The big question is, will therapeutic vaccines work as well as preventative vaccines,” Exley said.
Provenge, a prostate cancer treatment vaccine developed by the Seattle biotechnology company Dendreon, prolonged the lives of men in a critical clinical trial announced in April.
In the study, Provenge extended median survival by 4.1 months, compared to placebo and improved three-year survival by 38 percent.
The study involved men with metastatic prostate cancer who were no longer responding to treatments intending to deprive their tumors of testosterone, which fuels prostate cancer.
Simo Arredouani, an instructor in surgery at BIDMC, has received awards from the Prostate Cancer Foundation and the Department of Defense for his research to develop a second generation, “off the shelf” vaccine that can be used universally. Provenge must be custom made for each patient using each patient’s own cells.
Arredouani and his collaborators, Dr. Martin Sanda, Director of the BIDMC Prostate Center, and Dr. Towia Libermann, Director of the BIDMC Genomics Core, have identified 15 proteins expressed by prostate cancer that may serve as targets for a vaccine. Two of these, known as ERG and SIM2, appear particularly promising, he said.
In studies using humanized mice -- mice that carry functioning human genes, cells or tissues -- the researchers were able to generate an immune response by injecting the vaccine -- parts of these proteins called peptides -- into the mice.
Future studies of such mice with cancer will test whether the injections actually work against the cancer itself.
“We’re hoping it will reduce the tumor size,” Arredouani said. “That will be a wonderful thing if it happens. We don’t have any choice other than to be optimistic. What we are doing is really promising.”
If the upcoming studies show the vaccine works in mice, human studies could begin within a year or two, he said.
Exley, Dr. Steven Balk and others at BIDMC are working on a complimentary approach. Funded by the Harvard Cancer Center Prostate Cancer `SPORE’ and the DOD, the research is looking at using “natural killer” T-cells (NKT) that are designed to kick-start a patient’s own immune system. These cells could be incorporated into a vaccine that already has a cancer component. These killer cells already exist in the body, but in small numbers.
This research includes using monoclonal antibodies to expand the number of NKT cells to help the body in its fight against cancer cells.
The approach has been tried successfully in mice and a trial is currently underway using it in patients with melanoma, since patients with that disease sometimes go into remission when their own immune systems are able to battle the cancer to a draw, sometimes for years, Exley said.
Studies by Exley and others of patients with advanced cancers have found they had fewer NKT cells than healthy people and also found defects in the NKT cells they did have, “as if the immune system had lost a battle,” he said.
“Our goal is to provide reinforcements to win the next battle and the war,” he added.
Above content provided by Beth Israel Deaconess Medical Center. For advice about your medical care, consult your doctor.
Posted September 2009
