Vaccine Clears Out Leukemia Cells
A leukemia vaccine developed by Kimmel Cancer Center researchers Douglas Smith, M.D., and Hy Levitsky, M.D., appears to get rid of cancer cells left behind after treatment with the drug Gleevec. While the findings are preliminary, the investigators are cautiously optimistic that the vaccine could improve treatment outcomes and reduce toxic side effects for patients with chronic myeloid leukemia (CML).
The researchers are now conducting additional studies to confirm that the favorable responses were solely due to the vaccine.
"We want to get rid of every last cancer cell in the body, and using cancer vaccines may be a good way to mop up residual disease," says cancer immunology expert Hyam Levitsky, M.D., who collaborated with Dr. Smith to developed the experimental vaccine.
While most patients with CML will need to remain on Gleevec therapy for the rest of their lives to remain cancer free, about 10 to 15 percent of patients cannot tolerate the drug long term.
"Ultimately, should this vaccine approach prove to be successful, the ability to get patients off lifelong Gleevec therapy would be a significant advance," says B. Douglas Smith, M.D.
Gleevec was introduced about a decade ago as one of the first targeted therapies in cancer and widely celebrated for its ability to specifically destroy malignant cells in patients with CML. While the drug has led to very good responses in many patients, it does not kill all of the cells leaving some patients at risk for relapse, particularly if they stop Gleevec therapy.
The vaccine developed by Dr. Smith and Dr. Levitsky is made from CML cells irradiated to halt their cancerous potential and genetically altered to stimulate an immune response against other CML cells. In the initial trial, it was given to 19 patients whose cancer was no longer responding to Gleevec therapy. After an average of six years of follow up, 13 patients saw declining numbers of cancer cells, seven of whom had no measurable evidence of disease.