In yesterday’s post, Provenge, Its Future & A Clinical Trail Alternative for Men with Hormone Dependent Prostate Cancer, I said that I attempted to get into a vaccine trial, but was rejected because I have a history of an autoimmune disease and I have had evidence of some lymph node involvement (stage D1). I want to talk more today about the trial that rejected me.
I have made it very clear that I am a believer in the future potential for vaccine therapy for prostate cancer treatment and so I wanted to be on the cutting edge. Vaccine therapy for cancer is different than vaccine’s designed to prevent illness. Cancer vaccine therapy is designed to teach the immune system to recognize cancer cells as foreign, invading bodies. Remember, cancer is not an organism from outside your body, but is your own cells growing and multiplying in an out of control manner. No matter how you cut it, cancer is your own body, it is not a bacteria or a virus, although some cancers may result from a bacteria or a virus.
Since cancers are your own cells, your immune system does not recognize it as a threat and ignores it. Without your immune system seeing your cancer cells as a threat, the cancer is allowed to progress and grow without any attempt to make a counter action. Eventually, the cancer will overwhelm you and kill.
Cancer vaccines are designed to teach your immune system to see the cancer cells not as your own body, but as an outside threat. Once recognized as a threat, it is hoped that the immune system will sweep into action and attack the rogue cells.
As of today, the FDA has not approved any type of cancer vaccine, but we are hopeful that within this month they will make history and approve the first cancer vaccine, Provenge.
As I wrote yesterday, I believe that Provenge will be approved, but only for men with advanced, hormone resistant prostate cancer. The clinical trials that did demonstrate a survival advantage over chemotherapy were only evaluated on men with hormone resistant prostate cancer, and thus, if approved, the approval will probably be restricted to men fitting this diagnostic category.
The trials of Provenge did demonstrate that the therapy needs time to start working. Men in more advanced disease stages will tend to die sooner, sometimes before they have had adequate time to obtain the benefit of the treatment.
The trial I was rejected from, which is designed to test an different vaccine treatment than Provenge, is looking to recruit men in an earlier stage of disease, men with recurrent prostate at stage D0. This would allow men still hormone responsive to participate in the trial. According to the NCI web page stage D0 is: “A prostate cancer stage defined by the Jewett staging system. Stage D prostate cancer is cancer that began in the prostate and has spread to lymph nodes near or far from the prostate, or to other parts of the body, often to the bones. Stage D is divided into stages D0, D1, D2, and D3. In stage D0, the level of prostatic acid phosphatase (PAP) is high (editors note – PSA increase only or biochemical failure, in other words no sign of metastatic disease. )……” Stages D1 and higher involve evidence of metastasizes outside the prostate gland.
This trial is a Phase I Randomized Pilot Study of Epitope-Enhanced TARP Peptide Vaccine Versus TARP Peptide-Pulsed Dendritic Cells in Patients with Biochemically Progressing Stage D0 Prostate Cancer (NCI-09-C-0139).
According to its Principal Investigator, Dr. Jay A. Berzofsky, NCI Center for Cancer Research this trial is important because, “Treating early-stage prostate cancer with surgery or radiation therapy provides long-term disease-free survival for the majority of patients, but between 30 and 40 percent of men will experience a recurrence of their disease within 10 years. When prostate cancer recurs, those who are eligible often receive androgen deprivation therapy, which can be very effective initially. Eventually, however, the cancer acquires the ability to grow without the help of male hormones, and then the outlook is poor.
Scientists believe that immunotherapy has great potential as an alternative approach in treating recurrent prostate cancer, if it can be used as soon as increasing PSA blood levels indicate that the cancer has recurred and has likely spread beyond the prostate. In the Jewett staging system for prostate cancer, this is called stage D0 disease.
In this phase I trial, researchers are testing a vaccine to treat stage D0 prostate cancer. The researchers are evaluating the safety of the vaccine and whether the body’s immune system will respond to it by producing immune cells called T lymphocytes that will selectively attack cancer cells.
Specifically, the vaccine is designed to stimulate the immune system to attack cancer cells that express a protein called T-cell receptor gamma alternate reading frame protein, or TARP, which has been found in more than 90 percent of prostate cancer samples. The vaccine is made by combining natural and modified fragments (peptides) of TARP that were shown in previous laboratory and animal studies to stimulate T-lymphocyte immune responses.
Because the best method of administering the TARP peptides is unclear, the researchers are testing two different approaches. Half of the patients will receive the peptides along with an immune adjuvant, which is a substance that enhances immune responses set in motion by other agents (vaccines, bacteria, viruses, etc.). The remaining patients will be injected with dendritic cells that were taken from their bodies and exposed to the TARP peptides in the laboratory. Dendritic cells are immune cells that take up substances and display them on their surface to T lymphocytes, stimulating an immune response. Using dendritic cells in this way has shown promise in animal and some human studies.
“This setting is an opportunity to take advantage of recent advances in immunotherapy,” said Dr. Berzofsky. “We are starting to harness the exquisite specificity of the immune system to selectively target cancer cells without harming a patient’s normal cells.”
If you have recurrent prostate cancer with a biochemical only recurrence you may wish to take advantage of this trial. If they would have taken me I would already have been signed on to the trial.
To learn more about this trial including a complete list of the entry criteria and contact information go to vaccine therapy for men with progressive stage D0 prostate cancer or call the NCI’s Clinical Trials Referral Office at 1-888-NCI-1937. The toll-free call is confidential.
Joel T Nowak, MA, MSW