Deadly Leukemia Tamed by Novel Immune System Gene Therapy
Genetically engineering a person’s immune system cells to recognize an aggressive form of leukemia led to remissions in five patients, including one whose cancer was wiped out in just eight days, researchers said.
Acute lymphoblastic leukemia, which can kill in weeks when left untreated in adults, appears vulnerable to manipulation of the immune system, a study in the journal Science Translational Medicine found. Previous research found a similar approach could lead to remission in the slower-moving chronic lymphocytic leukemia, even in those who had failed other treatments.
Patients with relapsed acute leukemia have a “dismal” prognosis, with long-term survival only in a few who respond to chemotherapy and complete a stem cell transplant, researchers said. The findings, released yesterday, have implications for patients battling leukemia now and may offer powerful new ways to combat more common tumors like lung and breast cancer in the future, said Renier Brentjen, an oncologist at Memorial Sloan- Kettering Cancer Center in New York.
“This gives us something to offer patients when previously there was nothing,” he said in a telephone interview. “Their illness was for all intents and purposes terminal. You have a disease that has a very bad prognosis, but we have a new therapeutic entity that may enhance long-term survival.”
The researchers took T-cells from the patient’s own immune systems, which are supposed to recognize and fight infection, and programmed them to detect an antigen found only on healthy and cancerous B cells. Brentjen described the approach as “forcefully re-educating” the immune system to recognize and destroy cancer cells.
The findings should encourage researchers to expand the approach to other malignancies, though it may take some time to find suitable targets for the immune system, he said.
Two patients with the most cancer experienced a so-called “cytokine storm,” with high fevers and plummeting blood pressure that led to monitoring in the intensive care unit. The others had relatively few symptoms, and were sent home two days after the new immune system cells were infused, Brentjen said. The findings suggest the approach may work best early in the disease, when there is little tumor present, he said.
“This is a new drug,” he said. “It’s a living drug, but it’s a new drug. As with any new drug, you have to first show that it works. Then you have to find out how it works best.”
One of the patients in the study relapsed and subsequently died, while the others went on to receive bone marrow transplants and showed no signs of cancer. A second patient died from a suspected blood clot in the lungs while in remission.
Future studies will determine whether it should be given to patients before other therapies and whether patients, like those in the trial, will need bone marrow transplants to rebuild their immune systems or if they can skip the toxic treatment. More work is also needed to see if the destruction of healthy B cells caused by the treatment leads to a weakened immune system and future infections. Those long-term side effects could be addressed with existing treatments, Brentjen said.
The approach is similar to that used at the University of Pennsylvania in patients with chronic lymphocytic leukemia, though the researchers used different viruses to deliver the genetically engineered cells and a slightly different method. The two centers are collaborating on a follow-on study in patients with chronic leukemia to see which is best.
Novartis AG (NOVN) acquired the University of Pennsylvania’s technology as part of a $20 million pact to fund a research center at the school last summer. Brentjen said his group will also need sponsors to finance bigger studies needed for U.S. regulatory approval of the approach.
“Hopefully the interest that this paper creates will be enough to get outside investors involved,” he said. “We could keep doing small trials, but it would never been enough to persuade the Food and Drug Administration to approve these drugs. If we need to license our intellectual property, then that’s what we will do.”
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