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Cancer Vaccines

Cancer vaccines have been around for many decades and yet the earliest forms of vaccines did not provide much of improvement in survival of patients.

Vaccinations have been used for decades in prevention of infectious illnesses, by way of which, healthy individuals are given small amount of bacterial or viral antigens (molecules).  The immune system reacts to this exposure by producing immunity that will last a long time.  If the same individual is on a later date exposed to the actual Bacteria or Virus, and since he has already a past exposure to the infectious material, therefore his immune system is able to mount a strong immune reactions and prevent the illness from happening.

Vaccines are made of either dead or weakened bacteria or viruses.  Recent technology has made it possible to actually produce the specific molecules of the viruses in laboratory and use them for vaccination ( Hepatitis B Vaccine)

The situation is slightly different in cancers.  Cancer vaccines introduce cancer antigens to the patients who already suffer from cancer.   Cancer vaccines have not been developed to prevent a cancer from happening in healthy individuals, and in contrary they are used to treat an existing cancer or to prevent a cancer that was already treated from reoccurring.

Cancers are much more complicated than infectious illnesses.   We know significantly much less about cancers than we know about bacteria and viruses.  Therefore the cancer vaccines today are at their infancy and we hope to be able to have a better understanding of the interaction of immune system and cancers.   This will lead the way to development  of better therapeutic methods.

With our current knowledge and technology, today we have two basic forms of vaccines. Autologous ( tumor extracted form the patient and used in the same patient) and Allogeneic ( tumor extracted from others) tumor vaccines.  

Undefined Multiagent Vaccines were the earliest forms of cancer vaccines which were formulated from whole tumor and cancer cells, using either Autologous or Allogeneic tumors.  Most these studies revealed no benefit at all.

Autologous Melanoma Vaccines: Genetic engineering technology  has now mad it possible to produce cancer cell that can stimulate the immune system of the recipient of the vaccines.  Such cells have been engineered with added ability to produce various molecules in addition to their inherent antigens.  This constellation has shown to produce an immune response with resultant inflammation and death of cancer cells.

Allogeneic Melanoma Vaccines: To produce an effective Allogeneic vaccine, one has to learn and prove the concept of shared molecules among  tumors obtained form various individuals.  One product under study now is Melacine made by Ribi ImmunoChem research Inc.

Defined Melanoma Vaccines: Another approach to develop cancer vaccines has been to construct vaccines to react to specific antigens that are shared among cancer cells.   One such antigen in Melanoma is called GM2 and this vaccines is being studied now.   GD3 is another antigen and the vaccine is also under investigation.

Since most antigens are proteins and there is a gene for each protein that is produced, one can introduce the gene for the desired protein into the cells of the recipients.  This is a rather interesting and challenging method and involved gene therapy.