Researchers from the Penn State College of Medicine have made a discovery that may help treat acute myeloid leukaemia (AML). The research, published in the Blood Cancer Journal, shows that exhausted immune cells may be responsible for patients having a relapse.

AML is an aggressive form of cancer that affects the blood and bone marrow. There is no effective treatment for this form of leukaemia and it has a survival rate of only 5% after 5 years. AML makes the bone marrow produce abnormal blood cells and platelets. 

Chemotherapy is normally used to treat the disease, but it can also damage the healthy cells within the bone marrow. Stem cells can be transfused to help rebuild the body’s ability to generate healthy blood cells and regain immune system function. They can also help the body fight leukaemia cells by rejecting them — a process called graft-versus-leukaemia (GVL).

The researches attempted to understand why GVL failed to work in some patients. They compared the blood of patients who relapsed to those who did not, post stem cell treatment. They discovered that people who relapsed had exhausted T cells.

T cells are lymphocytes produced by the thymus gland, that play an important part in immune system response. The compounds that T cells send out help to eradicate leukaemia cells. However, eventually the T cells become exhausted and no longer function effectively. 

Patients with exhausted T cells had higher levels of PD-1hiTIM-3+ cells and their immune system was impaired compared to other patients. There is already a drug on the market that blocks T cell exhaustion in patients with solid tumours. Researchers may be able to use the drug post stem cell treatment to combat T cell exhaustion.

Spotting the presence of the PD-1hiTIM-3+ earlier can also help researchers understand which patients have a greater chance of relapsing.

Source: Discovery offers hope for leukaemia relapse post stem cell treatment

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