Patients with advanced prostate cancer do have options—ones that not only extend their lives, but also the quality of their lives.
Today, we have a Q&A with our very own Dr. Michael J. Curran, who discusses one of these important therapies: immunotherapy for advanced prostate cancer.
First, what is advanced prostate cancer?
DR CURRAN: Prostate cancer comes in many forms. We typically see patients as they progress through an elevated PSA and local or "primary" therapies (e.g. radiation, high-intensity focused ultrasound, radical surgery, and so forth).
After primary therapy, a number of patients will unfortunately experience a biochemical recurrence, which means that their PSA is rising after they've had initial treatment for their prostate cancer. Regardless of what their primary therapy was, a rising PSA is a poor prognostic indicator, yet one that we can manage with hormone therapy.
Hormone therapy involves administrating medications (sometimes oral, but mostly injectable) that will help put the patient's cancer into a state of remission. The goal is to lower the patient's testosterone, which is the fuel for prostate cancer. By lowering the testosterone, the cancer will go into a period of near remission.
However, we cannot get a patient's testosterone levels to zero, so there will always be stimulation of the androgen receptor inside the cancer cells. While the PSA may come down to zero and the cancer slows, we can't bring it to a complete halt. That said, the hormone therapy will work for the majority of our patients for the remainder of their lives because most of these patients tend to be older.
Some patients, however, will get to the point of "castrate-resistant prostate cancer" (CRPC), which is advanced prostate cancer where the cancer is no longer held in suppression by having low levels of androgen in the blood stream. These patients now have what we term "incurable prostate cancer." If the CRPC patient receives no other interventions, they will have a one- to two-year life expectancy, on average.
What options are available to patients with castrate-resistant prostate cancer?
DR. CURRAN: There are now therapies that allow us to increase that patient's life expectancy, provided we can intervene with the right drugs at the right time and early in the patient's progression.
At Greater Boston Urology, we have an advanced prostate cancer therapeutics center where we actively and aggressively manage our patients on hormone therapy to identify them as early as possible when they develop castrate-resistant prostate cancer. The therapy for these patients is immunotherapy.
What is immunotherapy? Is it like chemo?
DR. CURRAN: Immunotherapy is different from chemotherapy. To put it simply, chemotherapy is exposing the human body to poisons and toxins that kill our cells. The goal is that they kill more cancer cells than they kill our normal cells, but chemotherapy isn't natural to the human body.
Immunotherapy, on the other hand, uses something that is natural to our bodies—our own immune system—to kill cancer cells. When immunotherapy is properly targeted and channeled, it successfully kills cancer cells and has tremendously lower side effects than chemo.
Is there a specific type of immunotherapy that GBU uses?
DR. CURRAN: The immunotherapy that we use in advanced prostate cancer is a drug called sipuleucel-T. The brand name is PROVENGE. Many patients who have metastatic prostate cancer, a rising PSA, and are on hormone suppressive therapy will benefit significantly from having an early introduction of this immunotherapy to their prostate cancer.
At Greater Boston Urology, we are committed to getting our patients this treatment as early as possible in their cancer course because that's when the drug will have its greatest impact or benefit.
How does it work?
DR. CURRAN: Immunotherapy involves a cycle of three infusions. Before each infusion, we have to harvest the patient's immune cells—the white blood cells.
Every treatment starts with a visit to an apheresis center. At that visit, a patient will undergo a process of apheresis, which involves having two IVs inserted into the patient's arms (if the patient has poor veins, we may put in a central catheter).
Apheresis involves "pulling" the patient's blood and running it through a machine that will separate the red blood cells (our oxygen-carrying cells) from our white blood cells (our immune cells). We harvest the immune cells after they're separated from the red blood cells. We then give the patient's red blood cells right back to them at the same time.
Because we're only collecting a portion of the white blood cells and we're returning the red blood cells, the side effects of apheresis are very mild. Patients may have a low-grade fever, they may get a slight chill, or they may be tired from the procedure, which can take two to three hours. Other than that, the only other complaint patients have might be some soreness from the IV sites.
Once we collect these white blood cells, we then ship them to Dendreon, the company that takes the patient's immune cells and turns them into PROVENGE. There is a laboratory in Atlanta, Georgia, where we send the white blood cells. These immune cells go through a multi-step process to "teach" them to identify prostate cancer. This takes two or three days. Dendreon then sends the newly trained cells back to us.
The patient comes to our office, and we re-infuse these "educated" white cells back into the patient.
At this point, the cells have the ability to do two things. First, they can recognize prostate cancer cells in the patient and begin killing those cells directly. Second, these newly educated cells have the ability to "teach" other immune cells the signals needed to recognize prostate cancer. Essentially, they can recruit other immune cells to do the same thing inside the patient's own body.
With the current protocol for PROVENGE, we perform this process with apheresis and a re-infusion three times for the patient. By this time, we typically see increases in the patient's ability to attack and destroy cancer cells—in fact, this goes up by a factor of several hundred times higher than what the immune system could do on its own. It is this direct effect of cancer killing that gives patients a longer life expectancy.
How long does PROVENGE extend a patient's life, on average?
DR. CURRAN: We're seeing patients live outwards of four to five years from the development of castrate-resistant prostate cancer. The key is to implement these therapies at their earliest possible time.
Are there any side effects?
DR. CURRAN: Since we're administering a drug that is the patient's own blood, side effects are minimal. Typical side effects may be a low-grade fever, slight chill, or sometimes some nausea. In my experience, every patient we've treated so far has tolerated this procedure very well.
The only caveat that we have seen is there is a slight occurrence of stroke in patients who've had PROVENGE infusions, although a cause-and-effect relationship has never been established. We believe that the treatment is very important to extend not only a high quality of life to our patients with this advanced cancer, but also overall life as well. In addition to this new therapy, we can then implement other therapies to extend patients' lives even further.
Are there any down sides?
DR CURRAN: Our biggest frustration with PROVENGE at this point is that it does not cure the prostate cancer. However, we are encouraged that with ongoing research in the fields of immunotherapy, chemotherapy, and hormone therapy, someday we will have a cure for this now incurable disease.
Does health insurance typically cover PROVENGE treatment?
DR. CURRAN: Because of its technical nature, PROVENGE is a very expensive procedure. Medicare covers it, and so do most private health insurances. Before we perform the procedure, however, our business office and our experts in reimbursement will clarify that the patient has benefits that will cover the procedure. If the patient does not have benefits and we cannot perform the procedure, we will assist the patient in finding a facility that may be able to offer free care to the patient.
Are you interested in learning more about PROVENGE for prostate cancer? Contact us today.