The immune system only reacts to antigens, or proteins, located on the surface of the cell. These antigens are foreign to the body and therefore not usually found in it. A powerful attack on cancer cells is therefore only likely when cancer cells express antigens, which healthy cells do not express. The cancer cells do not produce signals of growth, like bacteria do, to warn and trigger an immune response reaction. That is why the cancer cells can live undisturbed in our body without getting attacked by the immune system.
Luckily, there is good news. In a study from June 2016, scientists have found a way to launch the immune system’s direct attack on cancer cells. A group of scientists have developed a vaccine consisting of a small particle; a Nanoparticle vaccine, which consists of RNA-lipid complexes. RNA, or ribonucleic acid, is responsible for the formation of proteins, or in this case the proteins usually expressed by cancer cells, while lipids are fatty acids. The lipids protect the RNA from being broken down in the blood. RNA-lipid complexes, which were slightly negatively charged, were more easily transported to parts of the body with a large concentration of dendritic cells, a cell in the immune system important to effective attacks.
In a study involving vaccinated mice, the scientists observed that the dendritic cells, which absorbed the complex could transform the RNA into protein. The dendritic cells present the protein to the so-called T cells, the immune system’s “killing machine”, and the T cells thereby become capable of attacking and killing the cancer cells which express the protein. In mice with for instance lung metastases, those that were given the vaccine were free from metastases after only 20 days. In other studies, the growth of the tumors stopped. After several promising studies using mice, the study was expanded to include patients with melanoma skin cancer.
First and foremost, the vaccine was well tolerated by the patients, seeing as only a few showed flu-like symptoms. In the study, the scientists used similar Nanoparticles with RNA coding for tumor antigens and discovered that the three patients produced a strong T cell response against these antigens. One patient showed a reduction of metastases in the lymph nodes, and another patient, who had metastases removed before the vaccination, was tumor-free after seven months. The third patient did neither experience an improvement or worsening of the condition in the duration of the study. The results show that the vaccine has great potential in the treatment of cancer in the future.
The RNA-lipid vaccine is neither expensive nor time-consuming to produce, and it therefore likely that a vaccine of this kind will be used in the treatment of cancer in the future. The next step involves testing the vaccine on more patients to gain a wider understanding of its effects and potential for curing cancer. In addition, more knowledge is needed to ensure that the harmful side effects do not outweigh the positive effects.
Hopefully, these new observations will contribute to a reduction of the waiting time before a cure for cancer is found.
