Cancer research is always ongoing in the hope to find a cure for cancer, but the reality is that one drug or a one-size-fits-all treatment is not enough to fight it. Immunotherapy is considered the next big thing in treating cancer, but cancer is smart has many ways of avoiding treatment. One new drug being developed provides a double whammy, that stops two ways of cancer cells avoiding destruction, and helps the body eat and destroy cancer cells.
The new drug boosts the action of white blood cells, called macrophages, that the immune system uses to destroy unwanted invaders. Dr Ashish Kulkarni who works at Brigham and Women’s Hospital in Boston, USA where the new treatment is being developed, described microphages as ‘the Pac-Man of immune cells’ as they are good at fighting bacterial and viral infections because they can recognise and engulf ‘foreign’ invaders. However, they are not as effective at fighting cancer as the tumours grow from cells already in the body and they have tricks to hide from immune attack. In normal circumstances, M1-type microphages engulf and destroy the invaders, while M2-type microphages are involved in tissue repair and wound healing.
Cancer cells can avoid destruction by microphages in two ways. Firstly, they can send out a ‘don’t eat me’ signal that tricks M1 microphages into leaving them alone. Secondly, they can convert M1 microphages into M2 microphages, thus eliminating the threat of being destroyed. This is also a major issue as M2 microphages can actually help tumours to grow, as they cannot distinguish the cancer tissue from healthy tissue. The new drug blocks the signal that the cancer cells use to trick M1 microphages and at the same time, cuts down on the conversations of M1 microphages to M2 microphages. It is the first time that these have been combined into one delivery system.
Dormant cancer cells are notoriously difficult to detect among normal cells in the body, so the key to this new research was fine-tuning the method of detecting and isolating them. The study tested the new drug on mice with aggressive forms of breast and skin cancer. The mice that were left untreated formed large tumours by day 10, mice treated with therapies that are already available showed a decrease in tumour growth, but the mice treated with this new therapy had a complete inhibition of tumour growth.
It is hoped within a few years this treatment will be ready for trials in humans and will be used to educate the immune system to make sure it can target cancerous cells. The researchers in the US are hoping that the approval process will be hastened by the fact that the drug they have designed already has a licence.