An experimental therapy that harnesses the power of the immune system is showing remarkable success in the fight against some of the mostly deadly blood cancers.
The work, headed up by Stanley Riddell, a researcher at the Fred Hutchinson Cancer Research Center in the U.S. state of Washington, involves engineering the patient's immune system T-cells and has shown considerable promise in small clinical trials.
In one study of 35 patients with acute lymphoblastic leukemia, or ALL, 94 percent experienced a complete remission. Fifty to 80 percent of patients with other blood cancers, including non-Hodgkin's lymphoma, also saw a reduction in symptoms.
"So, this is encouraging because these are all patients who have failed all conventional therapies, including many kinds of bone marrow and stem cell transplants,” Riddell said. “So these patients really do not have any other treatment options that are likely to put them into remission. So, getting these very high rates of remission is obviously very exciting for us."
Immune system T-cells, which usually fight invading viruses and bacteria, can also mount a response to cancer, but they are soon overwhelmed by the disease.
The work by Hutchinson researchers enhances this natural cancer-fighting ability.
Riddell and his colleagues tagged patients' T-cells with cancer-specific receptor molecules that recognize and attack malignant cells.
In this case, the T-cells were targeted at a series of blood cancers caused by a malfunction of B-cells, another immune system cell.
Once the T-cells were modified, Riddell said, they were infused back into the patient, where they multiplied and continued to fight cancer.
"So, that's the one interesting thing about this. It doesn't require repeated treatments or repetitive cycles of chemotherapy,” Riddell said. “That's what I think in the future may be most important for patients — that it's a single treatment instead of many months of treatment."
‘Living’ cancer therapy
Manipulating the immune system has already shown promise against melanoma, a lethal form of skin cancer, and some lung cancers. But currently, immunotherapy is considered a treatment of last resort for other cancer patients.
Riddell thinks that may change.
"You know, we still have a lot of work to do to establish exactly where the place of immunotherapy would be in cancer therapy,” he said, “but there's no question now that it is becoming a very useful modality and, in some cases, is a replacement for, or just superior to, chemotherapy."
Riddell and his colleagues presented details of their "living" cancer therapy, as they call it, at the recent annual meeting of the American Association for the Advancement of Science.