Antibodies for melanoma: details
The immune system has found an assistant in the fight against cancerAlexey Tymoshenko, GZT.RU
Clinical trials of the method of combating skin cancer based on strengthening the immune response of the body have yielded a positive result.
This is reported by American doctors.
Looking ahead, we note that the new method has nothing to do with all sorts of dubious drugs that promise to simultaneously "raise immunity" and heal almost all diseases from colds to cancer. A team of doctors and scientists from the Dana-Faber Cancer Institute conducted clinical trials of antibodies to a malignant skin tumor, melanoma.
Melanoma close-up.
The appearance of new spots on the skin or the change of existing moles
– a reason for a visit to a dermatooncologist;
at an early stage, the prognosis is quite favorable (up to 98% of patients are cured).
Source: National Cancer Institute
Their results (F. Stephen Hodi et al., Improved Survival with Ipilimumab in Patients with Metastatic Melanoma) are presented in the New England Journal of Medicine (one of the three most authoritative medical publications) and so far we are not talking about a panacea, but a remedy that will be used in combination with traditional therapy.
Is melanoma a cancer?
Strictly speaking, melanoma cannot be called "cancer", since in the Russian medical literature the term "cancer" refers only to tumors arising from epithelial cells. Melanoma is a consequence of a malfunction in the genetic program of melanocytes, pigment cells of the skin. The term "blood cancer", by the way, is also incorrect, and "lung cancer" can even mean several different neoplasms. But in the popular retelling, "cancer" will designate all malignant tumors.
How does the body fight danger?
There are about one hundred trillion (100,000,000,000,000) cells in a healthy body, most of which regularly have DNA molecules damaged by chemicals or radiation. And most often these damages are immediately corrected by special enzymes so that they do not have any consequences for the cell and the whole body as a whole.
Even where the repair system (or, to use a biological term, "reparations") DNA does not cope, most often nothing terrible happens. The mutated cell may not be viable, the mutation may affect the so-called "garbage" sections of DNA, or the damaged gene itself will not differ so much from the original one.
To turn into a cancer cell, it is necessary that DNA damage occurs in certain places, not immediately eliminated – and that's not all. A single cell is highly likely to be recognized by the immune system and destroyed even before the formation of a tumor.
DNA damage by free radicals does not mean a certain mutation with a fatal outcome: most defects will be corrected by the cell's own defense mechanisms.
The figure shows the last of the five stages of DNA repair (restoration of the correct sequence of nucleotides): the DNA ligase enzyme closes the last bond in the polymer chain and thereby restores its continuity.
Russian Roulette
Since the body has several levels of protection against the formation of tumors, it is necessary to talk about prevention or, on the contrary, an increase in risk only in terms of probabilities. That is why the presence of smokers who smoked a pack of cigarettes a day for up to a hundred years does not refute the harm of tobacco – as well as the presence of people who survived a fall from the roof of a multi-storey building does not prove the safety of such jumps.
For this reason, it is extremely difficult to verify the effectiveness of drugs that are designed to reduce the risk of cancer, since such studies require several thousand, or even tens of thousands of subjects for their reliability.
How does the new method work?
It was the immune response of the body that scientists decided to use. The experimental drug consisted of antibodies to tumor cells – protein molecules synthesized when the immune system of a melanoma focus is detected. Antibodies interact with so-called T-lymphocytes, activating the system of destruction of affected cells.
This simplified scheme can give some idea of the complexity of the whole underlying T-cell reaction "mechanics".
Source: BioLegend
However, it is not only the tumor cells that suffer. 60% of patients had some kind of complications: from skin rashes to diarrhea and vomiting. The remedy turned out to be far from harmless, but effective: the average survival rate of patients with inoperable tumors increased from six months to ten months. And 9 out of 15 patients who received only the new drug lived at least two years after the start of treatment.
The prospects
The fact that the experimental method has passed the third stage of clinical trials and has shown its effectiveness means that it can be used in the usual way. At least until widespread use is less than if we were talking about successful tests on animals or even more cell cultures – doctors say that now it is necessary to develop the most effective strategies for using the drug in the treatment of melanoma.
In addition, knowing the mechanism of interaction of antibodies with T cells, doctors can pick up other molecules that act in a similar way. This can both increase the effectiveness of the method and, quite likely, reduce the severity of side effects.
Portal "Eternal youth" http://vechnayamolodost.ru10.06.2010