Vaccines and New Anticancer Therapies
The term Vaccine is universally associated with the concept of prevention. Prevention, in fact, has been the goal of vaccinations that have made it possible to eradicate many diseases caused by infectious agents and to save hundreds of millions of lives over the last two centuries. It is now a question of understanding how an approach originally conceived to prevent an infection can be transferred to oncology with a purpose that, with some exceptions, is instead therapeutic as it finds use in individuals who have already developed the disease.
Immune System and Cancer Cells
The immune system of an individual, in order to destroy a cancer cell present in the body, must recognize it as different from normal cells, ie as a “foreign cell”. The tumor that grows in a certain tissue or organ is made up of cells that have acquired new properties which often benefit for the survival and progression of the tumor itself. These abnormal cells have new characteristics, namely molecules called ‘tumor antigens‘, which the immune system can recognize as foreign and against which it can potentially react.
However, it happens very often that the immune response that is spontaneously generated towards these antigens is weak and ineffective. Cancer, in fact, uses all the means at its disposal to avoid being recognized and not generate a “danger” signal, as it usually happens when an infectious agent enters the body. Hence the need to help the immune system to activate itself and to make the best use of the mechanisms at its disposal to specifically attack the cells that present tumor antigens and destroy them.
Cancer vaccines represent a therapeutic approach, still being tested, which is part of the broader panorama of immunological therapies or those therapeutic options that aim to exploit the immune system, enabling it to recognize cancer cells and destroy them. Since we refer to treatments that are used when the tumor disease has already appeared in the body, the anticancer vaccines are called therapeutic vaccines.
Unlike those used to prevent infectious diseases, the vaccines used in Oncology have, in fact, the purpose of increasing the immune response against cancer cells that are already present in the patient. Ultimately, for both types of vaccines the goal remains the same, that isprotect the individual. In the first case, however, it is a question of preparing a “protective shield” before the enemy (the infectious agent) presents itself, in the second, however, the challenge is even greater since it aims to strengthen the immune system against an entity (the Tumor ) which is already present in the body and which often implements real strategies to not be recognized.
With respect to what has just been described, there are two particular types of anticancer vaccines used in oncology, which do not belong to the family of therapeutic vaccines but to that of preventive vaccines. In fact, in the case of cervical cancer and hepatocarcinoma, pathologies in which a virus is involved(respectively, the human papilloma virus and the hepatitis B virus), the vaccine is used with a preventive purpose.
The tumor antigens used in the preparation of the vaccine, in this case, are components of the structure of the infectious agent and, therefore, the immune response that is generated in the vaccinated individuals will be able to recognize and destroy the virus as it enters the body. In this way, by making the vaccinated subject more resistant to viral infection, the possible onset of the neoplastic pathology associated with that virus is also prevented.