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How to Get the Most Out of Mesothelioma Immunotherapy

Gut bacteria illustration

For patients with mesothelioma, there is a lot of excitement surrounding cancer immunotherapy.

Some ongoing clinical trials suggest immunotherapy may be more effective for treating mesothelioma than standard chemotherapy treatment.

For immunotherapy to work well, the patient needs to have a healthy immune system. In general, the healthier the immune system, the more likely a patient will respond favorably to immunotherapy treatments.

Ongoing immunotherapy research also suggests the microbiome, which is the community of microbes living on and in our bodies, can affect how well immunotherapy treatments work.

What Is the Microbiome?

The microbiome refers to the trillions of bacteria, viruses, fungi and other microbes that inhabit the human body.

We tend to consider bacteria and viruses as harmful to health. While it’s true they can cause colds, the flu and other miseries, not all microbes are harmful.

In fact, the microbes in the human microbiome play an important role in maintaining our well-being. For example, the microbiome in our gut plays a critical role in how the immune system works.

Some health experts even consider the gut microbiome a part of the immune system. Without a healthy gut microbiome, our immune systems do not function well.

In recent years, researchers have become more interested in how the microbiome affects cancer treatment, including immunotherapy.

Immunotherapy and Microbiome Research

Most of the microbiome-immunotherapy research has involved mice and rats. These studies point to the importance of having a rich variety of gut bacteria for immunotherapy to work well.

But a 2017 microbiome-immunotherapy analysis in human patients with melanoma agrees with the animal research.

For the melanoma study, the researchers examined the gut microbiome of 112 patients with advanced melanoma. All patients received immunotherapy called anti-PD-1 therapy.

PD-1 (programmed cell death-1) is a protein made by cancer cells that prevents a person’s immune system from killing cancer cells. Current mesothelioma clinical trials are studying how to block the protein and allow the immune system to destroy cancer cells without harming healthy cells.

Participants with a greater variety of gut bacteria at the start of the melanoma investigation were more likely to respond well to treatment. A good response meant their tumors decreased in size, disappeared or stabilized for at least six months.

The participants with a less diverse microbiome — one that includes fewer types of gut bacteria — were more likely to experience tumor growth during treatment. Their disease also stabilized for fewer than six months.

In summary: The wider the variety of bacteria inside the gut, the better the patients responded to immunotherapy.

Mesothelioma Patients May Benefit from the Microbiome

Anti-PD-1 immunotherapies currently being studied in mesothelioma clinical trials include:

  • Keytruda
  • Opdivo
  • Yervoy

Keytruda is the focus of an ongoing trial in six countries. These drugs are the same types of medication studied in melanoma patients.

The melanoma study does not prove cause and effect. It does suggest more variety in the microbiome could support a better response to immunotherapy for people with mesothelioma and other cancers.

Maintaining a Healthy Microbiome

Certain diet and lifestyle choices support a more diverse gut microbiome. A richer gut microbiome may support the body’s healthy response to immunotherapy.

The following steps support a varied and healthy microbiome:

  • Eat microbiome-friendly foods such as vegetables, fruit, nuts, seeds, beans, peas and whole grains.
  • Eat fermented foods such as yogurt, kefir and sauerkraut.
  • Get enough sleep. Most experts recommend between seven and nine hours of sleep per night and keeping consistent sleeping and waking hours.
  • Move your body every day. Avoid sitting for hours and enjoy daily physical activity such as walking.
  • Maintain a healthy body weight.

For healthier gut bacteria, experts also advise avoiding artificial sweeteners and taking antibiotics only when needed. They also recommend eating more high-fiber foods such as oatmeal, apples, bananas, broccoli, lentils and other edible plants.

These nutrition tips may not be appropriate for some mesothelioma patients during treatment.

Talk to your doctor or dietitian if you are losing weight without trying or have questions about your diet before, during or after mesothelioma treatment.

Suzanne Dixon is a registered dietitian, epidemiologist and experienced medical writer. She has volunteered with the National Cancer Policy Forum, Oncology Nutrition Dietetic Practice Group, American Institute for Cancer Research, American Society for Clinical Oncology, The National Academies of Sciences, Engineering, and Medicine. The New York Times and Time Magazine also have reviewed her cancer patient resources.

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