Heat Shock Proteins:
How They Work

Cancer cells are distinct from normal cells due to a number of mutations that cause them to be abnormal. These changes are found in both the primary and metastatic tumor cells, here shown as a cancer arising in the kidney with a metastatic tumor in the lung.

These changes are unique to the individual cancer and are represented as cancer-specific antigenic peptides within tumor cells.

When these cancer-specific antigenic peptides are not effectively recognized by the immune system, the cancer can continue to grow instead of being detected and eliminated by the immune system.

Heat shock proteins are transporters of peptides and are present in every cell of the body. Like normal peptides, cancer-specific peptides are transported by heat shock proteins.

Isolation of such heat shock protein-peptide complexes from tumors captures a wide array of important peptides that can help the immune system recognize the cancer.

Antigenics’ cancer vaccine Oncophage is produced from cancer tissue that is surgically removed from the patient and contains purified heat shock protein complexed to a multitude of antigenic peptides specific to the particular cancer.

After surgery, part of the patient’s tumor tissue is sent overnight to Antigenics’ manufacturing facility in Massachusetts, where the patient-specific Oncophage vaccines are made using a quality-controlled process. The vaccines are shipped to the treating physician for administration to the patient.

Oncophage is usually administered in the physician’s office as a series of injections. At the site of injection there are antigen-presenting cells – specialized immune cells that function to amplify the signal of antigenic peptides to the immune system.

Heat shock protein-peptide complexes are recognized by receptors on the antigen presenting cells and then taken up into these cells.

The antigenic peptides are transferred onto MHC molecules, which are presented on the cell surface. The cancer-specific peptides are now visible to the immune system.

Following this, antigen-presenting cells travel to the lymph nodes. In the lymph nodes, T cells recognize the antigenic peptides.

T cells are specifically activated against cancer cells bearing these peptides. Only cancer-specific peptides – not normal peptides – are able to activate T cells to react against cancer cells.

Such activated T cells divide, leave the lymph nodes and travel throughout the body to identify and kill cancer cells due to the specific activation against the diseased cells.

Oncophage is designed to specifically activate the immune system to target and destroy the patient’s specific cancer cells.