Cienciaes.com: New immunologically antitumor drugs.

2020-09-08 13:43:39

Thanks to research, we already have antibodies that, when injected into cancer patients, achieve greater activation of the immune system against tumor cells. These antibodies have been approved by various international drug agencies for use in the treatment of up to fifteen different types of tumors. In some cases, its use has led to cures that would previously have been impossible.

The antitumoral activity of the immune system also depends to a great extent on the activation of what are known as cytotoxic, or cytolytic, T lymphocytes. These are also the class of lymphocytes that are believed to provide the longest lasting immunity against the coronavirus. SARS-CoV-2, the cause of the disease COVID-19. Cytotoxic T lymphocytes are capable of killing cells that are diseased and, for this reason, pose a threat to the life of all cells in the body.

Cellular disease can also be caused by mutations in some genes that transform the cell into a tumor. In this case, the cell stops collaborating with the others and begins to reproduce without brake. Killer T cells can also detect tumor cells and kill them.

Killer T cells are not normally activated or capable of killing. They only activate when they receive a series of molecular signals for it. These signals must also be presented to them by cells specialized in activating them, which are the only ones that can authorize this activation. These cells are called antigen-presenting cells, since they present antigens, foreign molecules, that come from microorganisms and also from the mutated genes of tumor cells to T cells. Antigen presentation is associated with an activation order.

Antigen-presenting cells are also not continuously activated. They are activated only by detecting microorganism molecules or tissue damage caused by tumor cells. The activation of antigen presenting cells is a fundamental part of the so-called innate immunity.

These cells have molecular detectors on their surface or in their cytoplasm that detect certain molecules in the environment. One of these molecules is ADN. The presence of ADN free in the surroundings indicates that a microorganism is attempting to infect, or that some cells are reproducing in a disorderly manner and releasing ADN to the environment.

By detecting the ADN in the surroundings some antigen-presenting cells are activated. Its complete activation requires a protein called STING (acronyms that mean sting, in English, although the protein has nothing to do with it). The protein STING it allows antigen-presenting cells to produce and release proteins into the environment that will help more antigen-presenting cells to become active. In the end, a small army of activated antigen-presenting cells is generated, and this is the one that will achieve the correct activation of enough cytolytic T cells for defense.

The absence of the protein STING in laboratory mice has revealed that they are more susceptible to the development of tumors. Rather, activation of the protein STING by pharmacological means it has been shown to be effective in activating more cytolytic T cells and reducing the development of tumors.

A search for new drugs using state-of-the-art molecular biology technologies has been carried out by several research groups. The search was carried out with around one hundred thousand different molecules and revealed that two of those molecules could be good candidates for the pharmacological activation of STING.

One such molecule, called SR-717, has shown robust antitumor activity in laboratory mice with melanoma. Another molecule similar to this one that can be administered orally has also been shown to be effective against tumors in laboratory mice and, moreover, it is capable of enhancing the efficacy of the antitumor antibodies mentioned at the beginning.

Like almost all the news that science offers us, this is good news. Little by little, but inexorably, progress makes its way and promises a better and healthier future for the following generations.

Reference:
Pan et al., Science VOL 369, ISSUE 6506. 21 August 2020. Chin et al, Science VOL 369 ISSUE 6506. 21 August 2020.
Jorge Laborda. September 6, 2020
Popular works by Jorge Laborda

Your defenses against coronavirus