Dr. Buyyounouski: Yes there are, but the benefit is not well understood. Hormone therapy is a treatment that is currently being used to address this risk of spread. It’s routinely recommended for high risk patients where it’s given for two to three years. For intermediate risk patients it’s sometimes used but is currently the subject of ongoing clinical trials. The problem with hormone therapy however it has quite an extensive side effect profile, which has been talked about quite a bit recently because of some of the potential cardiac affects that could be fatal in addition to factors that affect quality of life, such as menopausal-like symptoms due to the low testosterone level. Charles elected to get the hormone therapy which is allowed on this study, but not everybody has to have the hormone therapy. Hot flashes, weight gain, sleeplessness, difficulty with erections, thinning of the bones, loss of muscle mass, and fatigue are associated with hormone therapy. It’s not part of the ProstAtak scene, so that’s a potential advantage too.
Is this more for a higher risk group of recurrence?
Dr. Buyyounouski: Whenever we learn about prostate cancer, the first thing we do is group patients into risk groups based on the risk of spread: low risk, intermediate risk, or high risk. They’re based on three factors: the PSA level, the Gleason score, and the exam. PSA’s less than ten are low, ten to twenty is intermediate, and more than twenty is high. Gleason scores six and less are low, seven is the middle, and eight, nine, and ten is high. For the physical exam, generally speaking patients who have palpable nodules that are outside of the prostate, they are considered high risk. If you’re low risk, surgery, external beam radiation, or brachytherapy by themselves without hormonal therapy are all equally effective in curing the prostate cancer and do so on average about ninety-five percent of the time. For intermediate risk patients the risk of recurrence with either surgery or radiation is about twenty-five percent, or one in four. For high risk patients it’s as much as fifty percent. The ProstAtak study is targeting intermediate and high risk prostate cancer patients. The idea is that by injecting ProstAtak into the prostate and combining it with radiation we’ll be able to better eradicate the cancer cells within the prostate and stimulate the body’s own immune system to help fight the cancer by showering the body with fragments of the prostate cancer cells which it can detect and fight so that it will kill cancer cells not only in the prostate but anywhere in the body where the prostate cancer can be lingering. This study is ideal for patients who are looking to avoid a surgery and have decided to have external beam radiation treatment, but are looking to help increase the odds of curing the cancer. The hope is that we can improve our cure rates from seventy-five percent to maybe eighty-five percent or higher.
Provenge is for metastatic disease?
Dr. Buyyounouski: Yes, it is.
Which is different?
Dr. Buyyounouski: It is for a different population. Provenge was shown to improve survival in the metastatic setting. These are patients much further down the road, so Mr. Ken for example: if his prostate cancer were to come back we would first know about that because he would have an elevation in PSA, a blood test; that’s how we monitor all of our patients. As the PSA levels increase, we may learn that it has spread to the bones at which time he might choose to have hormonal therapy, which is highly effective but only works for an extended period of time. At which point we usually have to go to second treatments like chemotherapies, and that’s where Provenge comes in. Provenge can help extend men’s survival, I think by about three months, once they have hormone refractory disease. Which is great, but the big goal is to have fewer patients with metastasis, fewer patients with hormone refractory disease, by curing more of them the first time around when we’re treating them with radiation.
So Provenge is for once the recurrence has happened?
Dr. Buyyounouski: Right. So this trial may define a new standard of care in the treatment of clinically localized prostate cancer. It’s standard treatment radiation with or without hormone therapy at the patient and physicians choosing versus radiation with ProstAtak. If we find that the patients who receive ProstAtak are less likely to have their prostate cancer come back, that will be the new treatment recommended to all men with newly diagnosed prostate cancer.
Does it look like it’s heading in that direction?
Dr. Buyyounouski: Yes it does. There is convincing evidence and what supports that is this trial was formulated together with the FDA on what is called a fast track. So when very promising results are presented and there’s a perceived benefit to patients, they like to institute this fast track mechanism so that we can learn the answer sooner than later. So that is exactly how this trail is being put forth.
If it does get approved, when can we expect it?
Dr. Buyyounouski: Hopefully the trial will be completed by twenty fifteen, but this is big stuff, very big. This is the only trial I’m aware of that is looking at combining immunotherapy with radiotherapy in the Phase III setting and only one of a handful of trials exploring systemic agents like ProstAtak with radiation. There may be more studies in the future, but right now there are very few studies that may change the face of prostate cancer treatment.
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