Immunotherapy — using one's immune system to treat a disease — has been long lauded as the "magic bullet" of cancer treatments, one that can be more effective than the conventional therapies of surgery, radiation or chemotherapy. One specific type of immunotherapy, called adoptive T cell therapy, is demonstrating promising results for blood cancers and may have potential against other types of cancers, too.
Here, Leslie Popplewell, M.D., associate clinical professor and staff physician in City of Hope's Department of Hematology & Hematopoietic Cell Transplantation, explains what this treatment entails.
What is adoptive T cell therapy and how does it work to treat cancer?
Every day, our immune system works to recognize and destroy abnormal, mutated cells. But the abnormal cells that eventually become cancer are the ones that slip past this defense system. The idea behind this therapy is to make immune cells (specifically, T lymphocytes) sensitive to cancer-specific abnormalities so that malignant cells can be targeted and attacked throughout the body.
Who would be good candidates for this type of therapy?
Currently, adoptive T cell therapy is mostly used to treat lymphoma and lymphoid leukemia, because these cancer cells have unique surface markers that we can reprogram T cells to recognize and attack. However, we also studying how to adapt this approach to treat other cancers as well, including myeloid leukemia, multiple myeloma and solid tumors.
What happens to the patient during this therapy?
First, we collect the patient's own T cells from the bloodstream, which takes about four hours. The cells are then modified to recognize the patient's cancer; a two- to three-week process in our laboratories. They are then frozen for later use as needed.
While the T cells are being modified, the patient undergoes an autologous stem cell transplant. Afterward, the re-engineered T cells are infused back into the patient so that they can kill any residual cancer cells that remained after the transplant. Depending on the type of cancer, its stage, the patient's health and other factors, some patients may receive the modified T cell infusions shortly after their transplant; others may get their infusions later on, when tests showed that the cancer has relapsed.
Are there any side effects to this therapy? How can they be managed?
This therapy is very well-tolerated by our patients. Side effects are generally mild and can include fevers, coughing and skin rashes, all of which can be managed with careful monitoring and appropriate intervention.
However, adoptive T cell therapy has been known to trigger cytokine release syndrome, a serious condition that can raise body temperature and lower blood pressure to dangerous levels.
This side effect has not occurred with City of Hope patients, emphasizing the point that this complex procedure should be done in a specialized setting — such as a comprehensive cancer center — with clinicians who are familiar and experienced in this approach.
What additional research is being done on adoptive T cell therapy?
Based on the positive results we have seen thus far with treating lymphoma and lymphoid leukemia, we are looking into tailoring this approach for other cancers. We currently have a clinical trial for ovarian cancer and are studying its viability for brain tumors. Both of these are difficult to treat diseases, so having a new way to target and attack these cancers will be immensely beneficial for these patients.
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