According to a recent article in the Harvard Gazette, researchers from Harvard announced the results of a study involving animal models that brought about immunity and lasting recovery against acute myeloid leukemia.
The new therapy is a biomaterial (synthetic)-based injectable vaccine that is combined with chemotherapy. The vaccine offers the potential to completely eradicate AML cells.
AML has been found to originate in the bone marrow. Oncologists are aware that even after a patient is in remission, cancerous cells may survive undetected.
Upon careful analysis of the bone marrow in the vaccinated mice, researchers found that there was no evidence of AML cells. They did, however, find many T cells which are a type of white blood cells that are essential to the immune system.
Forty Years With No Change In Therapy
For the past forty years the standard therapy for AML has been a specific regimen of chemotherapy. Patients receiving this aggressive therapy will generally be in remission shortly after the treatment.
However, the treatments do not entirely eliminate the cancer cells. About fifty percent of patients experience a relapse.
Post-remission options are bone marrow transplants or high doses of chemotherapy. In each case, as AML patients are mostly over the age of sixty, these treatments are aggressive and present a major risk. (AML is described more fully here.)
About the New Vaccine
The new AML vaccine primes the immune system to identify the AML cells which prompts it to attack the “foreign invaders” when they surface.
When the researchers initially injected the cryogel vaccine in the mice as a single agent the response was unsatisfactory.
However, when they combined the cryogel vaccine with chemotherapy, the combination not only eradicated the cancer but prevented further relapse. It is noteworthy that after substantial testing, there were no residual leukemia cells in the bone marrow of the mice.
Activating an Immune Response
Unlike traditional vaccines that are usually liquid, the new vaccine is composed of a small disk-shaped cryogel “scaffold” which is an element that holds tissues and cells together.
Two chemicals (biomolecules) are embedded within the scaffold and activate special cells which are key regulators of the immune system (dendritic cells).
The result is that cancer cells are targeted by the immune system which also provides long-term immunity from disease recurrence.
Confirming the Results
The research team injected the cryogel vaccine into cancer-free mice to test the vaccine’s efficacy in priming the immune system against AML cells.
The results were favorable in comparison to a traditional vaccine injection.
The second challenge involved injecting mice with AML cells to recreate the AML disease.
The mice receiving a blank scaffold or a traditional vaccine did not survive past sixty days. Yet the cryogel vaccinate mice survived.
Then the team took steps for further verification. Bone marrow from mice that had been vaccinated with the cryogel vaccine was transplanted into cancer-free mice.
The second group of mice, the recipients, were cancer free for at least fourteen days after they received the transplant. According to the researchers, this was proof that the donor mice were not harboring AML cells in the bone marrow.
The researchers heralded this as a “better than expected outcome”.
“This Was Completely Unexpected”
Then the researchers moved into another discovery mode, which was to re-evaluate the vaccine’s components and the reason for its effectiveness.
They tested vaccines with and without antigens, which are substances that produce an immune response. The unexpected results were that the vaccines without AML antigens provided the same protection as the vaccines with antigens.
This discovery led the team down avenues they had not even considered. They found that AML cells eventually enter the cryogel at a point where dendric cells accumulate and become activated.
Exploring this further, they discovered that when a large number of AML cells die after chemo exposure, the dendritic cells identify these dead cells to be antigens and use them to signal T cells to attack AML.
Encouraging Results
Motivated by these promising results, the researchers are continuing their efforts to develop a human vaccine that can prevent a relapse of the disease. They hope to extend this methodology to other blood cancers.
