Researchers at the Johns Hopkins School of Medicine in Baltimore (USA) found that a combination of vaccine and low-dose chemotherapy can "reprogram" pancreatic cancer, making it sensitive to immunotherapy.

These results are of great practical importance, since pancreatic cancer usually does not respond to immunotherapy, and at the current level of treatment less than 5% of patients can survive five years after diagnosis.

"Pancreatic cancer is one of many types of cancer in which insufficient tumor-infiltrating lymphocytes are formed, that is, the tumor is considered" non-immunogenic ".

The only effective treatment for this cancer is complete surgical removal of the tumor, but in 80% of patients after surgery there is a relapse of the disease, because of which they die without living and 5 years from the date of diagnosis. All this means that doctors need urgent treatment strategies, "said Dr. Lei Zehng, a professor of oncology and surgery from the Comprehensive Cancer Center Sidney Kimmel, a researcher at the Center for the Study of Pancreatic Cancer at the Johns Hopkins Hospital.

A new study, published in the journal Cancer Immunology Research, was conducted to find out how ductal adenocarcinoma of the pancreas can respond to a new vaccine.

This vaccine, called GVAX, was developed by Elizabeth Jaffee, a researcher at Johns Hopkins University. Dr. Jaffi "reprogrammed" the tumor to force the immune cells of the patients to attack the cancer.

Dr. Jaffi says that this vaccine has great potential, and it can be useful in fighting other types of cancer that are not sensitive enough to immunotherapy.

For their research, the team selected 59 patients with ductal adenocarcinoma of the pancreas. The study continued from 2008 to 2012. One group of patients received only the GVAX vaccine, the second group received the vaccine plus 200 mg / m2 cyclophosphamide, and the third group received the vaccine plus 100 mg cyclophosphamide orally.

The vaccine "created lymphoid aggregates", activating immune cells.

All patients underwent surgical treatment two weeks after the introduction of the vaccine. In the analysis of excised tumors, the researchers found that the vaccine causes the formation of tumors in structures called "tertiary lymphoid aggregates".

These aggregates, formed in 33 of 39 patients who did not show signs of cancer, help regulate the activation and movement of immune cells. In natural conditions in pancreatic tumors such aggregates are not formed.

"This suggests that the vaccine reprograms the lymphocyte structures inside the tumor," concluded Dr. Zheng.

"These lymphoid aggregates can really normalize the immunological balance inside the tumor, changing its environment and forcing" good "T cells to stand up to the fight against cancer," adds the inventor of the vaccine.

If you look closely, the researchers also found that tumors after experimental treatment became immunogenic. This means that the immune cells in the surrounding tissues began to rush into the tumor and kill cancer cells.

Tumors become immunogenic, because the ratio between T-effector and T-regulatory cells of the immune system increases. Scientists noted that the higher this ratio, the higher the survival of patients.

"Our study shows that for the treatment of non-immunogenic tumors, such as pancreatic cancer, an entirely new model of effective immunotherapy. In the future, we will study immunotherapy in combination with other drugs that are aimed at enhancing "good" immune signals and blocking "bad" ones, "said Dr. Zheng.

medbe. en.

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