How viruses can attack cancer cells

A research group in Tübingen has teamed up with international research partners to work on an ingenious and highly promising approach to treating cancer.

While tens of thousands of researchers around the world search for ways to protect human cells from virus infections such as Covid-19, a small group of researchers in the southern German university town of Tübingen is doing precisely the opposite. They are attempting to optimise viruses so that they penetrate specific cells and can then destroy them from the inside. That said, it is not just any cells in the body that are their target, but cancer cells. “Whereas normal cells sound the alarm bells, inform the immune system and ramp up the highest possible level of virus defence when attacked by a virus, most of these signalling channels are deactivated in cancer cells, which is why cancer cells are able to escape. We use this gap in the defence of cancer cells to attack them with particular viruses”, says Professor Ulrich Lauer, head of the virotherapy group at the Virotherapie Centrum Tübingen (VCT) at Tübingen University Hospital.

Successful cooperation with partners in the USA

Scientists and medical experts around the world are gradually recognising the enormous potential that virotherapy offers for the treatment of cancer – which poses one of the greatest challenges of our time. From the USA to China, new working groups have emerged in recent years, with centres and institutes even being set up in some places, as in Tübingen. This has given rise to all manner of collaborations. It is not geographical proximity that is the key factor in this context, but whether the research being conducted is on similar kinds of tumour and on viruses that destroy cancer cells – known as oncolytic viruses. Lauer and his team are cooperating with the Mayo Clinic in Rochester, USA, for example. Like the VCT in Tübingen, the researchers there are regarded as world leaders in virotherapy. “These days there is even an annual virotherapy congress, which is a bit like a class reunion”, says Lauer.

At the congress, results and interim progress are presented, everyone watching with interest to see what other researchers have achieved. One of the things Lauer and his team are currently looking at is how to treat cancer of the liver. They are working with the viruses that are used to vaccinate people against measles; the viruses themselves are harmless and will not actually trigger measles. Lauer and his colleagues have modified the viruses so that they target tumour cells. They have already seen some successes at cellular level and are now treating patients within the framework of several studies. “What is nice about our work is that we do bench-to-bedside research: we develop a treatment in our own lab and then also apply it to patients ourselves, meaning that we are responsible for the entire process”, says Lauer. More than 20 colleagues are working together in the studies and also sharing their findings internationally.

New chances of a cure for patients

What happens when everything goes well and the therapy is effective has already been seen a number of times, including at the Mayo Clinic in 2014. A woman with an advanced plasmacytoma – a form of leukaemia – was treated there; none of her doctors thought she had any chance of survival. But this is exactly what virotherapy achieved: “The plasmacytoma disappeared completely during a single course of virotherapy several years ago, and has not reappeared to this day”, says Lauer.

For many doctors, who know only too well how aggressive a plasmacytoma can be, this was nothing short of a miracle. For Lauer and his colleagues, it is above all confirmation that their research into virotherapy is a highly promising way to help bring humankind several major steps forward in its battle against cancer.