(RxWiki News) One of the challenges of leukemia is that it likes to return. Once the blood cancer comes back, it’s more difficult to treat and beat. Medical scientists are experimenting with a way to boost the body’s immune system to get in on the fight and win.
In a very small preliminary study, researchers infused huge quantities of immune system soldiers – T cells – into patients who had had stem cell transplants.
These T cells were programmed to recognize a specific molecule that leukemia patients have too much of - called the Wilm's Tumor Antigen 1 (WT1). Some of the cells were also exposed to another molecule - interleukin 21 (IL-21).
This treatment extended the lives of some seriously ill patients by many months.
More study is needed to investigate the safety and effectiveness of using such a therapy on larger groups of leukemia patients.
"Ask your doctor about the signs that leukemia has returned."
Researchers at Fred Hutchinson Cancer Research Center worked with 11 patients whose leukemia had returned after a stem cell transplant. These individuals were at high risk of dying at the time of the study.
Here’s how this pilot study worked, according to the authors. The procedure started in the lab. T-cells (white blood cells) were gathered from the donor who had given the stem cells for the transplant.
These cells were programmed in the lab to recognize WT1 and effectively kill leukemia cells.
Some of these cells were exposed to interleukin 21 (IL-21), a molecule that’s also a cancer fighter. The thought was that the IL-21 might pump up the anti-leukemia activities.
These specially engineered cells were grown in large quantities (billions) in the lab. The cells were then given to the 11 leukemia patients.
Four of the patients who received cells exposed to IL-21 went into remission (few or no symptoms) and required no additional treatment for more than two and a half years.
Only one of the patients had serious complications that can occur after transplants, called graft-vs.-host-disease (GVHD), in which the body attacks the transplanted cells.
Two of the patients who received cells that hadn’t been exposed to IL-21 had some anti-leukemia activity, according to the researchers. One patient with advanced progressive disease had a temporary response.
Only five of the original 11 participants were still alive at the end of the study.
Philip Greenberg, MD, head of the Immunology Program at the Fred Hutchinson Cancer Research Center, served as the corresponding author. "This is the first time patients have received an infusion of WT1-specific T-cells, and thus also the first demonstration that such cells can provide a therapeutic anti-leukemic effect, as has been suggested from earlier vaccine trials that induce less potent responses," Dr. Greenberg said in a press release announcing the study’s publication.
This pilot study included only a small number of patients. As such, much more research is needed to confirm the findings.
Results from this study were published February 27 in the journal Science Translational Medicine.
This work was supported by the National Cancer Institute grants and the Leukemia and Lymphoma Society SCOR program.
One of the authors holds a patent titled “Methods of using IL-21 for adoptive immunotherapy and identification of tumor antigens.” No other potential conflicts of interest were reported.