After 150 years, a new chapter in cancer therapy is finally beginning

For decades, researchers have been looking for ways to destroy cancer cells in a targeted manner without further weakening the body. But for many patients whose immune system is severely impaired by chemotherapy or radiation, such therapies often remain ineffective. Now Japanese scientists are providing a possible way out: a combination of two bacteria that control each other and attack cancer even without the help of the immune system.

The new therapy could help above all those people whose immune system is exhausted after cancer therapy – and for whom there are hardly any treatment options so far.

Two microbes, one task

A research team led by Eijiro Miyako from the Japan Advanced Institute of Science and Technology has combined two natural bacterial species: Proteus mirabilis and Rhodopseudomonas palustris. In a ratio of three to 97 percent, they form a consortium that the researchers call "AUN" – after a Japanese term for harmony.

These two microbes behave like partners: Proteus mirabilis penetrates deep into tumor tissue and changes its shape there to attack cancer cells. Rhodopseudomonas palustris regulates the process and prevents the bacteria from getting out of control or triggering inflammation. This creates a finely balanced balance that destroys tumors from the inside out, but spares healthy tissue.

"After 150 years, a new chapter in bacteria-based cancer therapy is finally beginning," says study leader Miyako. He is alluding to the fact that scientists first researched bacterial cancer treatment 150 years ago.

"Suffocating" the tumor

In the study published in the journal Nature Biomedical Engineering, the scientists investigated what happens in the body when AUN enters the bloodstream. The bacteria find their way to the tumour and begin to change its blood supply. Small clots form in the fine vessels, which only occur in the tumour tissue. As a result, the cancer is cut off from oxygen – it "suffocates" from the inside.

At the same time, the bacteria form fibre-like structures with which they directly attack cancer cells. This combined effect leads to a massive necrosis, i.e. to the death of the tumour tissue.

Teamwork significantly increases the impact

The team found that a two-stage treatment is particularly effective: first a small dose to accustom the immune system to the bacteria, followed by a higher dose. This procedure led to a complete decrease in tumours in all experiments – while at the same time being well tolerated.

Hope even for weak patients

Classic immunotherapies, such as so-called checkpoint inhibitors or CAR-T cell therapies, only work when the body's own defences are intact. In people who have already had several chemotherapy treatments, they usually remain unsuccessful. This is exactly where the new concept cats in: The bacteria attack tumours independently of Defence cells.

In the study, the researchers reported:

AUN completely eliminated tumours – even in animals whose immune system was barely active.

This opens up a completely new way of treatment for patients who have previously had no chance of immunotherapy.

No genetically modified microbes

Particularly remarkable: The researchers did not have to genetically modify the microbes. Both species exist in nature – Proteus mirabilis can also be found in small quantities in the human body, Rhodopseudomonas palustris in soils and waters.

They adapt in the tumour environment: one bacterium becomes more mobile and aggressive, the other ensures that the attack remains targeted. If unwanted reactions occur, the system can be stopped with common antibiotics. This could make the use for patients one day much safer than previous bacterial therapies.

Clinical study planned

The method is not yet approved for clinical practice. The team around Miyako is currently preparing the first studies with humans. In the coming years, safety, dosage and efficacy are to be tested.

The goal is to develop a therapy that fights tumours regardless of the state of the immune system. If this succeeds, AUN therapy could create a new treatment option – for those patients who previously had no hope of recovery.

Summary:

Von Anne Bajrica

The original of this article "New bacterial therapy destroys cancer even with a weakened immune system" comes from Smart Up News.