A fascinating new study, published in the Journal of Clinical Investigation, has revealed an unexpected potential benefit of severe COVID infection: it may help shrink cancer. This surprising finding, based on research conducted in mice, opens up new possibilities for cancer treatment and sheds light on the complex interactions between the immune system and cancer cells – but it certainly doesn’t mean people should actively try to catch COVID.
The data outlining the importance of the immune system in cancer is considerable and many drugs target the immune system, unlocking its potential, an important focus of my own research.
The study here focused on a type of white blood cell called monocytes. These immune cells play a crucial role in the body’s defence against infections and other threats. However, in cancer patients, monocytes can sometimes be hijacked by tumour cells and transformed into cancer-friendly cells that protect the tumour from the immune system.
What the researchers discovered was that severe COVID infection causes the body to produce a special type of monocyte with unique anti-cancer properties. These “induced” monocytes are specifically trained to target the virus, but they also retain the ability to fight cancer cells.
To understand how this works, we need to look at the genetic material of the virus that causes COVID. The researchers found that these induced monocytes have a special receptor that binds well to a specific sequence of COVID RNA. Ankit Bharat, one of the scientists involved in this work from Northwestern University in Chicago explained this relationship using a lock-and-key analogy: “If the monocyte was a lock, and the COVID RNA was a key, then COVID RNA is the perfect fit.”
To test their theory, the research team conducted experiments on mice with various types of advanced (stage 4) cancers, including melanoma, lung, breast and colon cancer. They gave the mice a drug that mimicked the immune response to a severe COVID infection, inducing the production of these special monocytes. The results were remarkable. The tumours in the mice began to shrink across all four types of cancer studied.
Unlike regular monocytes, which can be converted by tumours into protective cells, these induced monocytes retained their cancer-fighting properties. They were able to migrate to the tumour sites – a feat that most immune cells cannot accomplish – and, once there, they activated natural killer cells. These killer cells then attacked the cancer cells, causing the tumours to shrink.
This mechanism is particularly exciting because it offers a new approach to fighting cancer that doesn’t rely on T cells, which are the focus of many current immunotherapy treatments.
While immunotherapy has shown promise, it only works in about 20% to 40% of cases, often failing when the body can’t produce enough functioning T cells. Indeed it’s thought that the reliance on T cell immunity is a major limitation of current immunotherapy approaches.
This new mechanism, by contrast, offers a way to selectively kill tumours that is independent of T cells, potentially providing a solution for patients who don’t respond to traditional immunotherapy.
It’s important to note that this study was conducted in mice, and clinical trials will be necessary to determine if the same effect occurs in humans.
Maybe aspects of this mechanism could work in humans and against other types of cancer as well, as it disrupts a common pathway that most cancers use to spread throughout the body.
While COVID vaccines are unlikely to trigger this mechanism (as they don’t use the full RNA sequence as the virus), this research opens up possibilities for developing new drugs and vaccines that could stimulate the production of these cancer-fighting monocytes.