According to results from a recent clinical trial, the vaccine Oncophage® may improve survival in patients with advanced colorectal cancer.

The colon and rectum are both parts of the large intestine. Colorectal cancer is responsible for claiming the lives of nearly 60,000 people annually in the United States alone. Although cure rates are high when colorectal cancer is treated in early stages, prior to spread of the cancer, cure rates of more advanced cancer remain dismal. Stage IV colorectal cancer refers to cancer that has spread from its site of origin to distant and/or several sites in the body, often invading vital organs such as the liver. Standard therapy for colorectal cancer may consist of surgery, chemotherapy and/or radiation therapy. Researchers are evaluating novel treatment approaches in order to improve survival for these patients.

Oncophage® (HSPPC-96) is a vaccine that is composed of components of the patient’s own cancer cells and stimulates the patient’s immune system to attack the cancer. Every cell in the body displays specific antigens (small carbohydrates and/or proteins) on their surface. The immune system relies on differences in antigens to distinguish between healthy cells and non-healthy cells or “foreign” material, such as bacteria, viruses or cancer cells. Dendritic cells are specific immune cells that “present” or display antigens of non-healthy cells or foreign material to other cells in the immune system. The immune system then mounts an attack against the unwanted cells displaying the antigen(s) that were presented by the dendritic cells.

Heat shock proteins (HSPs) are proteins that exist in every cell in the body and their many roles are becoming more apparent to researchers. One important role of HSPs is to form a complex with antigens from a cell that is considered not healthy, such as a cancer cell. HSPs of a cancer cell form a complex with antigens specific to the cancer cell. Clinical studies have revealed that when HSPs from a cancer cell loaded with antigens bind to a dendritic cell, the HSP/antigen complex is internalized and biochemical processes occur within the dendritic cell that stimulate the immune system to attack the cancer. First, this process allows the dendritic cell to “display” the antigens specific to the cancer cells to other immune cells to initiate an immune response against the cancer. In addition, this process has been shown to induce dendritic cells to secrete cytokines, substances released into the lymph that stimulates immune cells, and to induce dendritic cell maturation.

Oncophage® is prepared by isolating HSPs/antigen complexes from a patient’s cancer cells obtained from the surgical removal of cancerous tissue. The HSP/antigen complexes are made into a vaccination to stimulate the patient’s immune system against cancer cells throughout the body. Patients typically receive Oncophage® once a week on an outpatient basis. Oncophage® is currently in the last phase of clinical trials prior to FDA approval for melanoma and kidney cancer.

Recently, researchers conducted a clinical trial to evaluate Oncophage® in the treatment of advanced colorectal cancer. This trial involved 29 patients who had colorectal cancer that had spread to the liver. All patients had complete surgical removal of their cancer and were treated with two cycles of Oncophage®. Approximately half of the patients (52%) demonstrated an immune response to Oncophage®. Two years following therapy, survival was 100% for those who responded to Oncophage® and 50% for those who did not demonstrate a response to Oncophage®. Cancer-free survival at two years following therapy was 51% for those who responded to Oncophage® and only 8% for those who did not demonstrate an immune response to Oncophage®.

The researchers concluded that Oncophage® may improve survival in patients with advanced colorectal cancer who demonstrate an immune response to treatment. Future clinical trials evaluating Oncophage® for colorectal cancer may help determine which patients are more likely to respond. Patients with advanced colorectal cancer may wish to speak with their physician about the risks and benefits of participating in a clinical trial further evaluating Oncophage® or other promising therapeutic approaches. Two sources of information regarding ongoing clinical trials include the National Cancer Institute (cancer.gov) and www.cancerconsultants.com. Personalized clinical trial searches are also available on behalf of patients at cancerconsultants.com.

Reference:

Antigenics. Phase II Results of Antigenics’ Oncophage Cancer Vaccine in Colorectal Cancer Featured in Clinical Cancer Research. Available at: http://www.antigenics.com/news/. Accessed August 25, 2003.

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