In the fight against cancer, there are many treatments that are emerging, being the immunotherapy one of the most innovative, although there are also other alternatives such as based on LED light. Now therapies continue to advance and science is already pointing to a group of bacteria to be able to destroy tumors without depending on the immune response, opening a new era in oncological medicine.
It’s not something new. The idea of using bacteria to treat cancer is not new: already in 1868 the German doctor Busch observed that some cancer patients experienced remissions after bacterial infections. Later, William Colby developed bacteria-based treatments that they laid the foundation of modern immunotherapy.
However, these traditional therapies require a functional immune system, which is a serious problem for patients who are immunocompromised due to cancer.
The present. a study published in Nature Biomedical Engineering presented an innovative “drug-free” strategy that uses a group of bacteria to fight cancer, rescuing this old idea of bacteria against cancer.
This treatment has not only demonstrated powerful antitumor efficacy, but it has done so by achieving complete remission of the tumor and, most importantly, it has been maintained for years in mouse models, even in those who are immunosuppressed.
The most relevant thing is that the fact that a bacteria helps us with this disease has been achieved without the need to use genetic engineering that alters your RNA. And also, without generating toxicity on the body. A priori they are all advantages.
A bacterial duo. The protagonists of this therapy are a bacterial group called AUN, composed of two specific bacteria: Proteus mirabilis (nicknamed A-gyo) and Rhodopseudomonas palustris (UN-gyo). And although we may all have in mind that bacteria are bad for humans, the reality is that They help us (a lot) starting with all those that are in our intestine.
When this bacterial duo was administered directly into the blood of tumor-bearing mice, the results were dramatic: complete tumor remission and prolonged survival. And it wasn’t magic.
How does it work? It is the obligatory question after seeing the results of this study. The researchers explain that what these bacteria do in short is block the arrival of oxygen and nutrients to the tumors, which literally causes them to suffocate. And a tumor is nothing more than a set of cells that have an advanced metabolism. When taking away their food they end up dead.
In essence, these bacteria can reach the tumor and enter its interior, as if it were a Trojan horse. Upon arrival, it causes very small blood clots to form and only in the blood vessels that go to the tumor. In this way, blood clots block the passage of blood and, therefore, its food source.
Bacterial transformation. Bacteria are STILL not passive agents, but are dynamic actors that change their behavior when detecting cancer. In this way, the study observed that the A-gyo bacteria undergoes a “wonderful fibrous transformation.”
This change is not random. It is specifically activated when the bacteria encounters “oncometabolites“, chemical signals emitted by cancer cells. This highly mobile form of “swarm”, together with the toxins and hemolysins secreted by the consortium, seems to be responsible for the tumor vascular destruction without affecting the rest of the healthy cells.
A safe treatment. Using live bacteria as therapy may sound risky, but the study spends much of its time demonstrating the safety and control of AUN. The first thing that has been seen is that the bacterial strains have a unique non-pathogenic profile.
Furthermore, to achieve a 100% complete response and avoid the lethality of a single high dose, the researchers developed a “double dose” regimen: a first injection at a low dose, followed days later by a high dose. The low dose “primes” the body, consuming aggressive neutrophils and mitigating the risk of severe cytokine release syndrome.
Looking to the future. Although the experiments were performed in mice, the therapy was tested against human cancer cell lines in xenograft models. In this case, cells from human colon adenocarcinoma, ovarian cancer and pancreatic cancer were used. The results in this case were very clear: all the tumors tested successfully disappeared in the mouse models, without very serious side effects.
In this way, we are faced with a therapy that does not require any type of drug a priori and that can be self-managed. The authors of the study point out that this approach can revolutionize cancer therapy, but there is still a long way to go.
Images | CDC
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