Immunotherapy for Prostate Cancer
Immunotherapy uses the body’s own immune system to recognize and attack cancer cells that have been hiding and targets them for destruction. This approach is quite different from that of other types of cancer treatments. Currently, one type of immunotherapy is approved to treat advanced prostate cancer, and it comes in the form of a vaccine.
Two types of vaccines are used against cancer: preventive vaccines and therapeutic (or treatment) vaccines. Preventive vaccines are given before a person develops cancer with the goal of stopping it from forming. Treatment vaccines may be given to treat existing cancers. Anti-cancer vaccines are created from either viruses or tumor cells that have been changed in a laboratory. Their goal is to direct immune cells to the cancer cells. Some of these vaccines are custom-made for the patient’s specific tumor type while others are “off-the-shelf” vaccines that contain one to more than 100 antigens that are common to the patient’s type of cancer. The first FDA-approved immunotherapy for prostate cancer is an antigen-presenting cell-based treatment vaccine specifically for metastatic castration-resistant (hormone refractory) prostate cancer (see Figure 2).
You may be a candidate for this treatment if you are on hormone therapy and have a rising PSA level, if your cancer has spread from the prostate to other places in your body, and if you are not taking narcotics for cancer-related pain.
This vaccine is unique in that it is personalized for each patient. As a result, getting it involves more than simply getting an injection at the doctor’s office. It is a multi-step process that requires a commitment from the patient, especially in terms of timing. If you are considering this option to treat your advanced prostate cancer, it’s helpful to be aware of what to expect.
Treatment begins with the collection of your blood cells in a process known as leukapheresis. Your blood is passed through a machine that collects some of your immune (white blood) cells, while the rest of the blood (platelets and red blood cells) is returned to your body. This is an outpatient procedure that typically takes about three to four hours.
The blood that was collected is sent to a special facility where the white blood cells are modified to be able to recognize and destroy prostate cancer cells. A dose of the vaccine is then created especially for you.
Three or four days later, you are given the dose of the vaccine by infusion (an intravenous fluid). This is generally given on an outpatient basis in your doctor’s office or treatment center and will likely take a little more than an hour.
This entire process is repeated two more times, approximately one to two weeks apart. You will have a total of six appointments — three cell collections and three infusions. The full treatment generally takes about a month.
Once these modified white blood cells are injected back into your body, they activate cancer-killing T-cells that travel through the bloodstream looking for cancer cells to destroy. A distinct characteristic of immunotherapy is its potential to remain effective long after treatment ends, a feature called “memory.” This means the immune system can continue to seek out and attack cancer cells until they are eliminated. When your immune system encounters a virus, such as chicken pox, it automatically remembers if it is exposed to it again and offers you immunity, meaning you usually don’t get another case of chicken pox. With immunotherapy, your immune system may be able to recognize a specific type of cancer cell easier, which can lead to long-term, cancer-free remission of that type and increased overall survival. This is the same characteristic that allows a traditional vaccine, such as the tetanus vaccine, to remain effective for many years.
It is crucial to stay on schedule with the cell collection and infusion appointments. The doses are made for you only, and they have an expiration date. If you miss an appointment and don’t receive the dose when you are supposed to, you must have your cells collected again so another dose can be made especially for you. Because a missed appointment will delay treatment, you are encouraged to be diligent about keeping your appointments. Consider asking a loved one or caregiver to help you remember, or explore the many online schedules and calendar apps that are available. Many have reminder features that are very helpful.
If you need additional treatment after receiving this vaccine, other options, such as chemotherapy, hormone therapy and radiotherapy, may be available to you. More immunotherapy agents, including other types of vaccines, are currently being studied in clinical trials (see Exploring Clinical Trials, page 12).
Common Side Effects
One of the potential benefits of immunotherapy is that it tends to affect only cancer cells. Other forms of treatment are more likely to affect healthy cells in addition to cancer cells. For example, surgery, chemotherapy, androgen deprivation therapy and radiation therapy kill rapidly multiplying cells, which include cancer cells as well as healthy cells that also multiply quickly, such as blood cells and cells in the gastrointestinal tract. The accompanying destruction of healthy cells and tissues contributes to common side effects, such as fatigue, nausea and vomiting, hair loss and low blood counts. Immunotherapy is different because it primarily targets cancer cells. Although there may be fewer side effects from immunotherapy than with other cancer treatments, it is realistic to expect that you will experience some (see Side Effects, page 13).
Since these drugs work by stimulating the immune system, it’s important to pay attention to every side effect you experience. Your doctor will monitor you closely for complications during treatment, and your medical team will rely on you to communicate your side effects frequently because they may develop rapidly and may range from mild to life-threatening. Seek treatment immediately, regardless of time of day, for symptoms including high fever, inflammation, swelling, severe abdominal pain or shortness of breath.
Ask your doctor which side effects to expect with vaccine therapy and when they may happen. Some may occur right away, while others may not show up for months or years after treatment. Once you know what to watch for, ask your doctor about the best ways to prevent or treat them if they occur. When in doubt about any side effects, contact your doctor.
PROSTATE CANCER TREATMENT POTENTIAL SIDE EFFECTS
Treatment vaccine therapy
- Back pain
- Fatigue (feeling tired)
- Joint ache
Illustration: Figure 1 Prostate anatomy (filename: Prostate Fig 1)
Illustration: Figure 2 Process of personalized vaccine therapy (filename: Prostate Fig 2)