In a new study published in the journal Cell Reports, the researchers have found a way to kill off the regulatory T cells, thus able to significantly increase the impact of the killer T cells. The study could pave the way for more effective cancer therapies.
Killer T cells are a powerful weapon of the immune system. Following a viral infection, they swarm out in huge numbers and destroy all of the infected body cells. Their destructive power is also directed towards cancer cells – at least in principle.
Many tumours possess mechanisms to avoid destruction by the immune system. To do this, they abuse the regulatory T cells that are also part of the immune system. However, fulfil an opposite function there: they suppress the immune response and thus prevent killer T cells from attacking healthy tissue in the body.
The tumours exploit this by pretending to belong to the body's own tissue. Thus, the tumours can be protected to a certain degree by the regulatory T cells. The study focuses on naturally produced IKKβ protein (immunostimulant), which has been known for long to promote the activation of immune cells.
The team blocked IKKβ in a test tube with the help of a pharmaceutical ingredient. The regulatory T cells died off afterwards. However, the killer T cells survived and even gained in impact because they were no longer inhibited by the regulatory T cells."
Then the researchers tested using mice with skin cancer whether the IKKβ inhibitor could be suitable for tumour treatment. The researchers treated the rodents with the IKKβ inhibitor shortly after the vaccination.
Following around two weeks of treatment, the number of regulatory T cells fell by 50%. The response of the killer T cells to a tumour was correspondingly stronger. The cancer growth was delayed significantly by this, and the animals survived for longer.
However, complete healing cannot be achieved solely by inhibiting IKKβ. By combining with other immunological active pharmaceutical ingredients, it may be possible to stimulate the immune system to more effectively combat cancer.
The regulatory T cells are actually only one element with which the body keeps its immune cells in check. Experts also refer to these braking mechanisms as immunological checkpoints. The researchers have succeeded in releasing these brakes using suitable inhibiting substances (the "checkpoint inhibitors"). The approach has revolutionized the treatment of cancer.