How to incite lymphocytes on a tumor

Cancer immunotherapy "dissolved" tumors in mice

Natalia Pelezneva, Naked Science

Researchers from Stanford University said that they managed to completely destroy tumors in laboratory mice using a combination of two substances that stimulate the body's immune system. The "mixture" is injected into the tumor by injection – according to scientists, this will help reduce the number of side effects of therapy. In 2018, researchers plan to study the effectiveness and safety of this technique for humans.

Immunotherapy is one of the promising areas of cancer treatment. Such methods make it possible to "mark" cancer cells and direct the activity of the body's immune system mechanisms against the tumor. The disadvantage of most immunotherapy technologies is their high cost. Another problem is that over time, tumor cells can suppress the activity of T cells involved in immune system reactions.

The authors of the new method combined two types of compounds. The first is a CpG oligonucleotide (a short fragment of DNA) connecting to a toll-like receptor 9 (TLR9). TLR9 enhances the expression of the OX40 receptor on T lymphocytes: this receptor ensures the division and survival of T cells, as well as the production of cytokines - peptide molecules that regulate interactions between cells. The second agent of the drug is antibodies to the OX40 receptor. This component stimulates the activity of the T-cell, causing it to attack the tumor. Since the "mixture" is injected into the tumor itself, the substances activate only the T-lymphocytes associated with it. About a microgram of the drug is needed for one injection.

In the tests, 90 mice were used, into whose body lymphoma cells were artificially injected. Each mouse had two tumors – at the right and left shoulder. The animals received injections into one of the tumors. After the injection, the tumors began to shrink, for 87 animals out of 90, the treatment was successful on the first attempt. At the same time, not only the tumor into which the injection was made decreased, but also the second, unaffected one. The therapy helped the three remaining mice on the second attempt. Further experiments have shown that the method works for mice with melanoma and tumors of the breast and colon.

Scientists plan to conduct a clinical study of the technique with the participation of 15 people suffering from lymphoma. The researchers believe that in the future, the technology can be combined with surgical treatment of tumors.

The study is published in the journal Science Translational Medicine.

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