Cancer is one of the leading causes of death worldwide, accounting for almost one in every six fatalities. 
According to researchers, the disease can develop as a result of immunosurveillance attenuation and immunological tolerance to tumor-derived antigens. Specific bacterial or viral infections have been linked to the development of several malignancies. Despite recent advances, cancer treatment outcomes for most types remain dismal.
Several cancer therapies, including surgery, radiation therapy, chemotherapy, targeted therapy, immune checkpoint inhibition, and hormone therapy, resulted from research into the molecular mechanisms of carcinogenesis, progression, and metastasis.
Chemotherapy and immunotherapy are treatment methods that stop cancer cell proliferation or stimulate the immune system to remove diseased cells. However, these are known to have toxicities or unwanted side effects on the body. [2, 3]
Researchers have discovered that diverse parts of the human microbiome can mediate the treatment-related toxicity of cancer treatments.
Cancer Treatment Studies Related to Gut Bacteria
A microbiome is an organism community composed of billions of bacteria and other organisms in your body. You have 10 times as many bacteria cells inside your body as human cells. These bacteria, viruses, fungi, and other microorganisms have an impact on everything from food processing to immune system reactions.
Babies begin to develop a microbiome at birth, which evolves through time based on genetics, lifestyle, age, and other variables. The majority of your microbiome can be located in the gut, and it is one of the most studied communities of microbes. However, since each person’s microbiome is unique, it’s incredibly hard to find patterns.
“Favorable” microbiota changes depending on the type of cancer. What constitutes a healthy and thriving microbiome is still up for debate and requires additional research. However, there have been individual efforts to explore the microbiome and its relation to cancer. 
Professor Emma Allen-Vercoe, a microbiologist at the University of Guelph, has dedicated her career to studying these organisms. Her early work provided the first indications that bacteria may be implicated in bowel disorders, including cancer. 
When people are told that they have small microorganisms in their gut, their initial response is that these microbes cause sickness and should be removed, but according to Allen-Vercoe, they are actually protective.
However, the types of bacteria that defend humans from disease and how they do so remain unknown. It is not as simple as contracting an illness and falling sick. It is not always the case of having a balance of “good” and “bad” bacteria either. “It’s more about how the body and other microbes interact with and control bad bacteria to neutralize them,” said Allen-Vercoe. [5, 6]
Jennifer Wargo, M.D., an MD Anderson researcher and surgical oncologist, has investigated the relation between gut microbiota and cancer. The aim is to determine whether managing the gut microbiome can promote health and treat cancer. Her team learned that bacteria, viruses, fungi, and other microorganisms normally prevalent in the stomach can either positively or negatively influence therapy response. In their recent study, it was discovered that gut flora can influence how cancer patients respond to treatment. [7, 8]
The gut microbiota is increasingly becoming recognized as a significant component in both tumor formation and anti-cancer therapy success. Specific gut bacteria have been found to influence cancer therapy via direct medication metabolism and host immune response modulation. 
More scientists are researching gut bacteria’s positive effect on cancer. According to MD Anderson Center, their researchers have now published more than 90 microbiome papers and conducted a dozen clinical trials studying everything from how diet to pre-surgery antibiotics affect the microbiome. 
Available Cancer Treatments via Gut Microbiome Regulation
It has been known that the microbiome could help improve how well cancer treatments work. Scientists are investigating several techniques for modulating the gut microbiome.
According to research, a person’s microbiome is a modifiable risk factor that can be targeted through diet, exercise, antibiotic or probiotic use, or fecal material transplantation (FMT). The use of especially immune checkpoint blockade medications can also be helpful, allowing the body’s own immune system to assault cancer cells.
FMT is a method where doctors take excrement from a healthy patient who responded completely to therapy and deliver it to another patient as a “poop pill.” Alternatively, they can create a microbe consortium, put it in a tablet, and provide it to patients. For now, this treatment still needs human data. 
In bowel cancer studies, treatment includes providing patients with C. difficile infection with an ecosystem of good bacteria in a capsule. Dana Faber scientists are also working on producing new medications that may be capable of destroying particular bad germs. The clinical sample library has also been continually expanding.
Furthermore, some reports show that certain diets are linked to the development of cancer or the effectiveness of cancer treatment. However, no prospective trial has found the exact link between treatment and diet. Patients may not adjust well to the new diet, which makes them less likely to follow it. Diet modification is likely to be used in the future as a supplement to therapy.
A New Drug for Cancer Treatment
The FMT method is considered a breakthrough, yet it’s hard to offer this as a primary treatment for cancer since there could be a limited supply of donors.
Although stool preparation is simple, the necessity to avoid cross-contamination means that researchers can only analyze one donor sample per day in a room. Even the most efficient academic facilities will most likely be unable to meet increased demand. Therefore, a need for a drug that can be replicated and mass-produced for cancer treatment arises. 
Biomica, an Israeli company, has started a clinical trial to see if its new treatment based on the microbiome could help some cancer patients respond better to immunotherapy.
Biomica gave its first patients BMC128, a new drug, in Phase I of its clinical trial. BMC128 has a “rationally designed consortium of microbes” that is made up of four types of bacteria. These bacteria were chosen based on Evogene’s “MicroBoost AI” tech engine and big-data platform. The microbes are made to bring back diversity and specific functions to the microbial community of the patient. This makes the patient more responsive to immunotherapy. 
The idea behind the drug is similar to probiotics, but it is based on a small number of bacteria, which makes it more effective and safer, according to Dr. Elran Haber, CEO of Biomica.
BMC28 is meant to help patients who don’t respond to immunotherapy. The company hopes that the trial will show that its BMC128 microbiome-based immuno-oncology drug candidate, when used with immune checkpoint inhibitor (ICI) immunotherapy, is safe and well-tolerated, and has some early clinical effectiveness.
ICI is a novel treatment that has proved its efficacy in extending cancer patients’ survival rates. However, many patients don’t respond well to ICI, and it has been demonstrated that the gut microbiome plays a significant role in this resistance. The trial began after successful preclinical research in mice. Investigations revealed that when BMC128 was given in conjunction with immunotherapy, it reduced tumor volume and enhanced animal survival when compared to immunotherapy alone.
A dozen individuals with non-small cell lung cancer, melanoma, or renal cell carcinoma are set to participate in the trial. Preliminary results are expected in 2023 and full research results later that year.
This is just the tip of the iceberg and there’s more to come regarding gut microbiome research, hopefully leading to the understanding of the relationship between the host microbiome and cancer treatment response that is confined to specific cancers.
Maintaining Gut Health
There has been significant improvement, but we still have a long way to go before we have a definitive cancer treatment pill. For now, we bear a great deal of responsibility for maintaining the overall health of our gut microbiota.
To learn more about your gut health, take our Gut Health Quiz to know and receive personalized diet and lifestyle recommendations to keep your gut in tip-top condition.
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