Personalized Cancer Vaccine Prevents Leukemia Relapse in Patients
A majority of patients in a small clinical trial have been in remission from a deadly type of cancer for more than four years.
Shortly after Ernest Levy of Cooperstown, New York, returned from a trip to South Africa with his son for the 2010 World Cup, he was diagnosed with acute myeloid leukemia. The prognosis didn’t look good for Levy, now 76. Just over a quarter of adult patients survive five years after developing the disease, a type of cancer that affects bone marrow.
Levy joined an early-stage clinical trial led by the Beth Israel Deaconess Medical Center, a teaching hospital of Harvard Medical School in Boston, testing a cancer vaccine for acute myeloid leukemia. After an initial round of chemotherapy, he and the other trial participants received the experimental vaccine, a type of immunotherapy intended to “reëducate” the immune cells to see cancer cells as foreign and attack them, explains David Avigan, chief of Hematological Malignancies and director of the Cancer Vaccine Program at Beth Israel.
Now results from the trial suggest that the vaccine was able to stimulate powerful immune responses against cancer cells and protect a majority of patients from relapse—including Levy. Out of 17 patients with an average age of 63 who received the vaccine, 12 are still in remission four years or more after receiving the vaccine, Avigan and his co-authors at the Dana-Farber Cancer Institute report. The researchers found expanded levels of immune cells that recognize acute myeloid leukemia cells after vaccination. The results appear today in the journal Science Translational Medicine.
Acute myeloid leukemia is typically treated with a combination of chemotherapies, but the cancer often relapses after initial treatment, with older patients having a higher chance of relapse.
Therapeutic cancer vaccines are designed to work by activating immune cells called T cells and directing them to recognize and act against cancer cells, or by spurring the production of antibodies that bind to certain molecules on the surface of cancer cells. But producing effective therapeutic vaccines has proved challenging, with many of these vaccines either failing outright or showing only marginal increases in survival rates in clinical trials.
Avigan and his colleagues created a personalized vaccine by taking leukemia cells from patients and then freezing them for preservation while they received a traditional chemotherapy. Then scientists thawed the cancer cells and combined them with dendritic cells, immune cells that unleash tumor-fighting T cells. The vaccine took about 10 days to manufacture and another three to four weeks before it was ready for administration.
Many cancer vaccine strategies have homed in on a single target, or antigen. When the antigen is introduced in the body via injection, it causes an immune response. The body begins to produce T cells that recognize and attack the same antigen on the surface of cancer cells. The vaccine Avigan and his team created uses a mixture of cells that contain many antigens in an attempt to generate a more potent approach.
Though the number of patients in the trial was small, Avigan says, “this was enough of a provocative finding” that the researchers will be expanding the trial to include more patients. At the same time, the personalized vaccine approach is already being tested in other types of cancers.
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