New immunotherapy launches a two-pronged attack against cancer

Cancer affects millions and millions of people every year. Scientists would like to encourage our own immune system to attack it, which is why immunotherapies are probably the most promising treatments for cancer.

Now scientists at UCL developed a new kind of immunotherapy, which launches a two-pronged attack against melanoma, some lung cancers, head and neck and some other cancers.

Most current cancer treatments are extremely damaging to the healthy body tissues. Image credit: Bill Branson via Wikimedia

There are several main ways to combat cancer, but all of them have their limitations. Cancer cells are not that different from healthy ones, which makes it difficult to remove them without affecting the healthy tissue too much. Immunotherapy could be a better answer, if we could train immune cells to recognize and kill cancer cells. Scientists are now targeting suppressive ‘regulatory’ immune cells, called Tregs, inside a tumour. They are often found in high numbers in the tumours and are believed to prevent other immune cells from eradicating the disease. Removing those tregs could help the immune cell deal with the cancer.

There is a protein marked as CD25 on the surface of each treg. Scientists have anticipated that targeting it will bring great results, but that hasn’t been the case so far. However, now scientists took a deeper look into the structure of CD25 protein and found that targeting it was a good approach, but a different part of it should have been targeted. Now scientists invented a new drug, which contains an antibody, which  binds to a different part of the CD25 protein to other currently available drugs.

Sergio Quezada, co-lead author of the study, said: “This drug not only eliminates the regulatory immune cells that dampen down the immune response to cancer, but also activates the cancer-killing immune cells. This two-pronged approach is a huge opportunity to significantly alter the tumour network of cells in and around the tumour, so they no longer protect the cancer cells, but start to turn against the tumour”.

Scientists already conducted testing with mice. In one experiment, all 10 mice who received the new anti-CD25 drug survived despite having cancer. This is a huge improvement over existing treatment (1/10 survival in mice experiments). And it allowed scientists to start clinical trials. This new drug allows the immune system to launch an aggressive attack against cancer, which could improve survival in such cancers as melanoma, some lung cancers, head and neck cancers.

Although testing with mice was successful and scientists are moving towards clinical studies, it will be years till we see these drugs in hospitals. They are not coming any time soon. We can just hope that they come at all – a lot of testing and development needs to be done, till the drug is accepted as safe and effective.

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