U.S. Team Crafts Chemotherapy-Free Stem Cell Treatment vs Leukemia

Stem cell transplants are often used to treat blood cancers, but the process can be risky. In a new study among mice, researchers at Washington University in St. Louis have developed a way to make the process safer by targeting a patient’s faulty stem cells more precisely, removing the need for radiation or chemotherapy, Michael Irving reported for New Atlas.

Photo Insert: Stem cells of human bone marrow

Leukemia and other blood cancers typically start in the bone marrow, where blood cells are produced by stem cells. For those with life-threatening illness, there’s one treatment option that can be very effective but carries a serious risk of side effects – hematopoietic stem-cell transplantation (HSCT). The research was published in the Journal of Clinical Investigation.

To prepare their body for donated stem cells, a patient is first given radiation or chemotherapy, which kills their own stem cells, destroys remaining cancer cells, and weakens their immune system to prevent rejection.

That boosts the chances that the new stem cells will take hold, and the procedure can functionally cure some patients of the disease. But it also puts them at high risk of infection or a dangerous condition called graft-versus-host disease, where immune cells from the implanted tissue attack the patient’s own cells.

In the new study, the researchers developed a technique that doesn’t require radiation or chemotherapy. Instead, the stem cells in bone marrow are targeted for destruction more precisely, using molecules called antibody-drug conjugates (ADCs.)

These bind to specific proteins on the surface of blood stem cells, which the team says keeps them from harming other cells. Once they reach their target, the ADCs release a drug called saporin to kill the stem cells.

After the donor stem cells are transplanted, immunosuppressive drugs are still required to prevent rejection. In this case, the team used a drug called baricitinib, which is currently used to treat rheumatoid arthritis. In tests in mouse models of leukemia, the technique resulted in successful stem cell transplants.

The combination of ADCs with baricitinib prevented the test animals’ immune cells from attacking the new stem cells, and they didn’t develop graft-versus-host disease because the immunosuppressants prevented it.

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