Researchers led by a UCLA bioengineer have developed a therapy based on two types of cells joined into a single unit that could help strengthen existing treatments for acute myeloid leukemia

One of the cells is a blood platelet that carries a drug that attacks cancer cells; the other is a stem cell that guides the platelet into bone marrow, the spongy tissue inside bone where new blood cells are made and where leukemia begins.

The researchers found that when injected into mice that had acute myeloid leukemia, the combination therapy halted the disease from developing any further. Of the mice that received the treatment, 87.5% were cured by 80 days after the combination cells were injected. Those mice were also resistant to leukemia cells that were re-injected two months after the 80-day period.

Zhen Gu, a professor of bioengineering at the UCLA Samueli School of Engineering who led the study, said the approach could be used in concert with other therapies, such as chemotherapy and stem cell treatment, to improve their effectiveness. Gu said the approach would have to be tested in human clinical trials and then approved for use before it could be incorporated into treatments for people with leukemia.

Immune system

Acute myeloid leukemia is cancer that starts in bone marrow and affects the precursor stem cells to white blood cells, which are a key part of the immune system. Cancer can spread to the bloodstream and other parts of the body. With a compromised immune system, a person with this type of leukemia could die from other diseases.

The UCLA-led research aimed at solving that problem by devising a method to deliver medicine directly into the bone marrow. Their approach, which they termed "cell combination drug delivery," is the first to link two different cells together for therapeutic purposes.

In the combined cells, the blood platelets are used to deliver immunotherapy drugs called checkpoint inhibitors (the UCLA researchers used a drug called an aPD-1 antibody), which seeks out cancer cells and neutralize their defenses. Once that happens, the body's immune system can "see" and destroy the cancer cells.

"This part of the cell combination is like a delivery truck," Gu said. "We can package medicines or immune system boosters on the cell surface of platelets, and have them activated to unload once at the target site inside the body."