Cancer Vaccines Con't

Cancer Vaccines con't 

Dr. Catanzaro posted and edited
Written By: Preeti Gokal Kochar



The idea behind the first cancer vaccine is attributed to Coley who, a century ago, observed that his cancer patients benefited from bacterial infection. This prompted him to treat the patients with bacterial extracts. It was not till the 1980s that development of cancer vaccines progressed further. While certain cancers have been successfully treated, progress has been relatively slow. The pace should increase substantially as scientists gain a deeper understanding of how the immune system fights tumors and as the success of the cancer vaccines now available is evaluated.

To learn how cancer vaccines work it is essential to start with insight into the working of the immune system. This review begins with a primer on tumor immunology: the identity and role of each cell involved in recognizing and fighting cancer. The next section explains how tumors actively try to evade the immune system, while the concluding section highlights the strategies used in designing cancer vaccines.

REVIEW SUMMARY

Immunology Primer

The immune system can be divided into two branches; both are involved in fighting cancer.

Innate: Barriers that human beings are born with, including special cells, to fight specific bacteria and other invaders. Natural killer cells are the most significant innate cells that fight cancer directly.

Adaptive: Response that the immune system generates to fight threats as they occur. Lymphocytes are cells involved in fighting these threats. There are two types of lymphocytes, B cells and T cells. Some lymphocytes are cells that trigger immunity, while other lymphocytes are memory cells that allow this adaptive response to occur repeatedly. Cytotoxic T cells are the adaptive cells that directly fight cancer. However, they cannot always recognize cancers and need antigen-presenting cells, dendritic cells, to help them do so.

Properties of Tumors

• Since they resemble normal cells, tumors tend not to trigger the immune system.
• Tumors also actively evade the immune system in different ways.
• Immune cells are not very efficient in detecting tumor growth.

Cancer Vaccines

• Vaccines boost the immune system.
• Preventive vaccines may be used to prevent cancers induced by viruses, such as cervical cancer.
• Most cancer vaccines will probably be therapeutic, used for patients who already have cancer.
• Cancer vaccines modify the immune system response to evoke a strong and specific immune response.
• Types of cancer vaccines include:
  - Tumor antigens used to familiarize the body against the cancer
  - Monoclonal antibodies to mimic tumor antigens
  - Stimulation of the cytotoxic T cells to fight the cancer