One of the most prominent approaches to immuno-oncology involves the development of cancer vaccines. While people may be familiar with vaccines that help prevent disease, much immuno-oncological research is focusing on how vaccines can optimize the immune response to specific tumors. Several preventative vaccines for cancer do exist, such as options for preventing human papillomavirus (HPV), which can lead to cervical cancer and other diseases.
Provenge is currently the only vaccine designed to boost the body’s immune system that has received approval from the U.S. Food and Drug Administration (FDA). In use clinically since 2010, the drug stimulates an immune response against metastatic prostate cancer. While Provenge is a customized approach to treatment that must be specifically engineered for each patient, its success has spurred a great deal of research in the application of vaccines in other types of cancer, including melanoma, brain tumors, leukemia, and breast cancer.
How Provenge Works
Provenge is indicated for the treatment of asymptomatic and minimally symptomatic metastatic, castrate-resistant, prostate cancer. The treatment is an autologous approach to boosting the immune system. The normal immune system uses antigen-presenting cells (APCs) to engulf foreign agents and then break cells down into pieces and display pieces of them on their surface. These pieces are antigens. The antigens direct T cells to destroy any cells that express these antigens. Some activated T cells become memory T cells that can initiate an attack in the future. Through this system, the immune system trains itself to recognize foreign cells.
Many cancer cells, including those of prostate cancer, are immunoevasive, meaning that they can trick the body’s immune response into not recognizing them as foreign or they can stop the body’s normal immune response. Provenge is designed to retrain the immune system to recognize cancer cells as foreign bodies to be destroyed. The process of creating Provenge for a patient starts with leukophoresis—the removal of blood and concentration of immature APCs. Then, scientist culture these cells with a recombinant antigen called PAP-GM-CSF. PAP (prostatic acid phosphatase) is an antigen that is expressed on more than 95 percent of prostate cancer cells. GM-CSF is involved in the maturation process of APCs.
During the culture process, APCs engulf the antigen and express them on their surface. After two or three days, the mature APCs can be reintroduced to the body through a blood infusion. The modified APCs activate T cells to attack the cancer cells. The T cells are now able to recognize prostate cancer cells that express PAP and will attack and destroy them. The infusion process is repeated a total of three times at two-week intervals.
The Benefits of Provenge
It is important to note that Provenge is not a cure for prostate cancer. Instead, it is a means of extending life. During the Phase 3 clinical trial for Provenge, the immunotherapy extended patients’ median survival time by more than two years. The immune response induced by Provenge has lasting effects with continued attacking of the cancer cells up to 26 weeks after the initial transfusion. While the FDA has only indicated Provenge for use in men with certain types of metastatic prostate cancer, researchers are currently examining the effect of the treatment when used with less advanced cases of the cancer.
Provenge has received a Category 1 recommendation for first-line treatment from the National Comprehensive Cancer Network. The side effects associated with Provenge are typically milder than those from chemotherapy or hormone therapy, with some patients reporting fever, fatigue, chills, nausea, headaches, and joint pain. Typically, side effects begin during the infusions and last only a few days. Some patients have experienced additional side effects, such as high blood pressure and difficulty breathing. These conditions usually respond to secondary treatment.
Getting Access to Provenge
Because Provenge is an autologous treatment that involves using the patient’s own cells, people may be apprehensive about the cost associated with the immunotherapy. However, the vast majority of patients who receive Provenge should have no out-of-pocket expenses associated with the treatment because it is covered by most commercial insurance plans and Medicare. Individuals can learn more about what their particular plans cover by speaking to their carriers and their doctor’s office. Dendreon, the company behind Provenge, also offers a number of assistance programs to ensure that cost is never a determining factor when considering the treatment.
Patients with Medicare can apply for co-pay assistance, which also covers co-insurance fees and deductible costs. In addition, the Provenge Uninsured Patient Program helps support patients without medical coverage by providing free treatment. Individuals can also apply to Dendreon for travel cost assistance, which helps patients afford the often-overlooked associated costs of treatment, including travel to a facility capable of providing the immunotherapy. Patients with commercial insurance can take advantage of the PROvide program, which covers a certain amount of co-pays, deductibles, and co-insurance fees over the course of the three treatments. Individuals can learn more at Dendreon.com or Provenge.com.