Tumor cell vaccines for melanoma involve the use of melanoma cells or parts of melanoma cells obtained from fresh tumors removed during surgery. Before they are injected into the body, the tumor cells are killed, usually by radiation, so they cannot form more tumors. But antigens remain on the tumor cell surfaces, so they are recognized by and may stimulate the immune system.

Sometimes dead tumor cells are mixed with immunological adjuvants, other substances that may increase the immune response and are meant to improve the effectiveness of the vaccine.

Tumor cells may come from the patient, another donor, or several donors.

• Allogeneic vaccines are made from melanoma tumor cells taken from individuals other than the patient.
• Autologous vaccines are made from melanoma antigens taken from a patient's own cancer cells

A variety of cancer cells and cell fragments are used in tumor cell vaccines:

• Whole tumor cells
• Tumor lysates: fragments of destroyed tumor cells
• Tumor oncolysates: an extract made from cancer cells infected with a strain of virus destructive to the cancer cells.
• Apoptotic bodies: fragments of cells that have died a natural death
• Transduced tumor cells: cancer cells altered through genetic engineering to include genetic material from cytokines, proteins that stimulate the activity of immune cells, including cytotoxic T cells

When injected into the body, these antigens are taken up by antigen-presenting cells (APCs), leading to one of the following series of events:

• The APC presents a fragment of the antigen on its surface. The antigen is recognized by its corresponding B cell, which stimulates the production of antibodies that target tumor cells with the same antigen presentation.
• The APC presents on its surface a fragment of the antigen along with a marker protein (MHC class II). The antigen/marker combination is recognized by helper T cells, which signal cytotoxic T cells to kill tumor cells carrying the same antigen.
• The APC presents a fragment of the antigen along with a marker protein (MHC class I). The antigen/marker combination is recognized by cytotoxic T cells, which directly kill similar tumor cells.

Clinical trials are currently underway to investigate the effectiveness of tumor cell vaccines as adjuvant therapy for high-risk melanoma.

• AVAX, an autologous whole tumor cell vaccine, is currently in phase III trials for patients with surgically resected high-risk melanoma.
• CancerVax is an allogeneic whole tumor cell vaccine. The bacterium Bacillus Calmette Guerin is used as an immunological adjuvant and the vaccine is injected into the dermis, or lower layer of the skin. Based on encouraging phase II results, two randomized, controlled phase III trials of CancerVax in the adjuvant therapy of high-risk melanoma have been designed and are ongoing.
• Melacine is an allogeneic vaccine derived from tumor lysates. A randomized phase III trial comparing Melacine to observation in patients with stage II melanoma showed no benefit for the treated group as a whole, but subsequent analyses showed potential benefit for subsets of the group.

See Clinical Trials for more information on these studies.