Catching crayfish for mutations

Mutations make tumors sensitive to treatment

Kirill Stasevich, "Science and Life"

Different cancers react differently to treatment, even if we are talking about some kind of advanced immunotherapy, like the one for which they gave the Nobel Prize last year. In some cases, tumor cells can be destroyed fairly quickly, in other cases, on the contrary, the tumor turns out to be very resistant to therapy.

Methods of treatment in oncology are fraught with side effects, and these effects in the case of immunotherapy can be especially sensitive (because stimulated immunity begins to attack not only diseased cells, but also healthy ones). And it is understandable why researchers are trying in every possible way to find a way to guess in advance how the tumor will react to this or that method of treatment: if it is known in advance that, for example, immunotherapy will give nothing but side effects, then it is not worth trying it.

The immune system recognizes malignant cells because they differ from healthy ones, and they differ because they have mutations. That is, on the one hand, it is because of mutations that the cell begins to divide uncontrollably, but they make it visible to immune hunters. Moreover, there are not one, not two, but many genetic defects in cancer cells. 

It can be assumed that the more mutations, the stronger the cell will stand out among healthy ones, and the easier it is for the immune system to detect it. Since immunotherapeutic methods are usually limited to stimulating human immunity against tumors, it is likely that such therapy will be most effective against tumors with the largest number of mutations.

Researchers from Memorial Cancer Center named after Sloan–Kettering analyzed the DNA of sufficiently developed tumors in more than 1,600 patients who were affected by immune control points (that is, they used the same Nobel treatment method when, roughly speaking, the brakes are turned off for immunity). In addition, tumor DNA was analyzed in more than 5,300 patients to whom this therapy was not used, but who were treated in other ways. The types of tumors were very different, from melanoma to breast cancer.

Similar studies have been performed before, but, as the Natur e portal writes, this time a very wide range of tumors were used in the work, which were also taken from patients after different types of therapy. An article in Nature Genetics says that immune therapy really worked best with those tumors that had the most mutations. But for different types of cancer, this threshold number of mutations was different. That is, therapy in which immune control points are affected and immune brakes are turned off should be correlated not with an abstract number of mutations, but also with a specific type of tumor.

However, as we know, mutation mutations are different, not all of them are the same and not all make the cancer cell more visible to the immune system. Therefore, if we talk about clinical prospects, then, probably, so that we can accurately guess the reaction of a tumor to treatment, we need to know not only the number of mutations, but also what they do in a cancer cell.

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