Vaccines can help treat certain cancers
Vaccines have been a standard part of staying healthy for almost 70 years, protecting children from deadly diseases such as mumps, chicken pox and rubella. Now, science is looking to vaccines as a way treat people who already have certain diseases, particularly cancer. These are known as therapeutic vaccines.
Prostate cancer vaccine
In 2010, Provenge® became the first therapeutic cancer vaccine to receive FDA approval. Provenge is an immunotherapy treatment for prostate cancer, specifically for advanced disease that has is hormone resistant and has spread beyond the prostate. FDA approval came after a large clinical trial found that Provenge lengthened median survival by 4.1 months, improved three-year survival by 38 percent and reduced overall risk of death by 22.5 percent.
Provenge is personalized cancer treatment, with each treated crafted specifically for the patient. For the vaccine to work, a man first must undergo a process called leukapheresis to remove his white blood cells, the cells the help fight infections. These cells then are exposed to a protein from the cancer cells and a stimulatory molecule. Then, the white blood cells are primed to activate the immune system, and identify and destroy cancer cells.
These activated white blood cells are used to create a vaccine for each patient. By stimulating the natural ability of immune cells re-injected into the body, Provenge may improve a patient's prognosis. The treatment typically takes six weeks, and is administered in three infusions every two weeks.
Men may qualify for the vaccine if they:
- Are on hormone therapy and have rising PSA levels
- Have metastatic cancer that has spread to the bone or soft tissue, not the lung, liver or brain
- Have minimal pain related to the cancer
- Are not taking narcotics for cancer-related pain
- Did not have chemotherapy in the previous three months
Provenge may be used alone or in conjunction with other treatments, such as radiation therapy and hormone therapy. It is recommended as a first treatment option for men who have advanced prostate cancer but few or no cancer-related symptoms. Chemotherapy may be used after taking Provenge.
Melanoma and bladder cancer vaccine
A preventive vaccine for tuberculosis called BCG, or bacille Calmette-Guerin, is also being used to treat bladder cancer and melanoma.
For bladder cancer, BCG is considered the most effective intravesical immunotherapy for early-stage disease. Intravesical immunotherapy delivers a drug directly to the bladder, instead of injecting the drug into a vein or giving it by mouth. This type of immunotherapy is only used for stage 0 and stage I bladder cancer because the drug is confined to the bladder and can’t attack cancer cells that have spread to nearby organs such as the kidneys and urethra.
BCG is infused through a tube or catheter directly into the bladder. The vaccine works in a similar fashion as Provenge, jumpstarting the immune system to find and attack cancer cells. Unlike Provenge, BCG does not require a patient’s white blood cells to work. A patient usually is treated with BCG a few weeks after undergoing a transurethral tumor resection. The vaccine is administered once a week for six weeks.
For melanoma patients, BCG boosts general immunity rather than specifically targeting melanoma cells. It can be directly injected into tumors of patients with stage III melanomas, which is the most advanced stage before the cancer has spread. Direct injection is typically not used for other stages of the cancer.
Melanoma is considered one of the most responsive cancer types to immunotherapy. As a result, researchers are looking into other vaccines that may be able to treat the cancer. Clinical trials are underway to study the efficacy of injecting destroyed melanoma cells or parts of the cells, called antigens, into the body to boost overall immunity. This type of vaccine would be similar to the preventive vaccines used for mumps, chicken pox and rubella, which have either weakened viruses or parts of a virus but do not cause the disease.
Clinical trials are also underway to evaluate how well vaccines can treat other types of cancers, including brain, breast, cervical, kidney, lung and pancreatic, as well as Hodgkin lymphoma, non-Hodgkin lymphoma and leukemia.