The Gut Microbiome May Protect Bone Marrow Recipients

Bone Marrow Transplant.jpg

Having a healthy gut microbiome before a bone marrow transplant is associated with increased post-transplant survival, according to a new study.

Blood stem cell and bone marrow transplants (BMTs) are used to treat many types of blood cancer. One of the most serious complications of this therapy, however, is graft-versus-host disease, wherein the donor’s immune cells attack the vital organs of the transplant recipient.

It can be lethal.

Recently, researchers have discovered that a transplant recipient’s gut microbiome plays an important role in their survival after a BMT.

Now, for the first time, investigators have found an association between the health of the gut microbiome before a transplant and a recipient’s survival afterward. The findings were presented at the annual meeting of the American Society of Hematology (December 2nd, 2018).

The researchers found that BMT patients who went into the transplant with a disrupted gut microbiome had a higher risk of death after the transplant.

The researchers studied 1,922 stool samples from 991 people receiving BMTs and evaluated them for a range of bacteria types, including commensals and those known to cause disease.

On average, the investigators found patients about to receive a BMT had reduced bacterial diversity in their microbiomes. They also found that different strains were dominant when compared to healthy volunteers.

Only 10-30% of patients had what researchers considered a balanced gut microbiome before their transplant

This is not surprising considering that most people with blood cancer who need transplants go through long periods of treatment with chemotherapy and antibiotics that throw off the normal, healthy microbiome balance.

Before a patient receives a BMT to treat their cancer, doctors run many tests (to verify heart health, lung and kidney function etc.) to make sure they are otherwise healthy.

This study suggests that doctors should also screen the microbiome. If they find dysbiosis (unhealthy gut microbiome), they may have to do something to repair it before the patient can receive the transplant.

Notably, scientists at Memorial Sloan Kettering are already testing the effectiveness of fecal microbiome transplants (FMT) prior to a bone marrow transplant. A recent study led by Eric Pamer and Ying Taur found that fecal transplants are effective in restoring the balance of healthy microbes that is lost during a BMT.

FMTs could become commonplace prior to bone marrow transplants.

Reference:

Taur Y et al. Science Translational Medicine, 26 Sep 2018: Vol. 10, Issue 460, eaap9489 DOI: 10.1126/scitranslmed.aap9489