blockbuster cancer drug may have a surprising new use: It’s showing real promise in treating severe asthma. That may help researchers better understand the basic biology of the chronic condition — and develop new medications, according to a small proof-of-principle study published on Wednesday in the New England Journal of Medicine.
The trial studied imatinib, known commonly under the brand name Gleevec, in 62 patients with severe and difficult-to-treat asthma. Imatinib is a chemotherapy used to treat leukemia and other cancers.
Imatinib has been found, in mice, to inhibit the growth of mast cells, which are a type of white blood cell that are found in the airways of severe asthmatics. It’s long been hypothesized that mast cells may play a role in asthma — causing airways to secrete mucus, for instance, and causing them to be hyper-reactive, or “twitchy,” in response to allergens or pollutants, said lead investigator Dr. Elliot Israel, a researcher at Brigham and Women’s Hospital.
The study backs up that hypothesis.
The patients studied were randomly assigned to either imatinib or a placebo, and followed for six months. The study found that the drug reduced the “twitchiness” in the airways, Israel said, and even helped open them up a bit.
Some patients who were given imatinib had side effects like muscle cramps and low white blood cell counts, though they rebounded after stopping the drug, Israel said. The researchers plan to expand the study and conduct a longer-term trial among more patients.
“It’s always been hypothesized that mast cells played a big role in severe refractory asthma, but this is an indication that therapy directed at mast cells does have an impact,” said Maureen George, an associate professor at Columbia University School of Nursing who conducts clinical research on asthma. She was not involved in the study.
Mast cells have been implicated in many allergic reactions — but as far as most scientists can tell, they’re vestigial and fairly useless in terms of helping buoy a person’s immunity.
“When we lived in a different environment, where there were lots of parasites, mast cells potentially might have been more useful,” Israel said. “But right now, they just contribute to hives, allergy, and asthma.”
So a drug like imatinib that inhibits mast cell development doesn’t run much risk of compromising the patient’s immune system, he said.
Imatinib just went off-patent last year. As with many cancer drugs, it’s costly: It was priced at $26,000 per year in 2001, but after years of cost inflation hit about $146,000 by 2016. The drug’s primarily used to treat chronic myeloid leukemia.
These findings are “of great value” from a proof-of-principle standpoint, said Andrew Long, lead investigational drug pharmacist at the Sean N. Parker Center for Allergy & Asthma Research at Stanford University. Importantly, he said, this could give drug developers new ideas for asthma treatments — since the study shows that mast cells are worth targeting.
“Pharma companies are already working on the sons and daughters of imatinib,” Israel said. “There’s room, I’m sure, to develop branded drugs in this space.”
Severe asthma is widely prevalent in the US. The Centers for Disease Control and Prevention estimates that 8 percent of Americans have asthma, and 1 in 10 have a serious and tough-to-treat form of the disease, Israel said.
Most new asthma drugs are targeted toward patients who have an allergic form of the disease — which accounts for about half of the serious cases, Israel said. Imatinib seemed most effective for patients without that form of asthma.
“If you want a population that’s in need of new therapeutic options, severe refractory asthmatics are definitely one to look at — and this study’s an intriguing new approach,” George said.
George, who conducts clinical research on asthma, pointed out that the study had a relatively high rate of discontinuation. Indeed, of the 32 patients that were given imatinib, eight stopped taking the drug — compared to four patients that dropped out in the placebo set. That’s “a pretty high dropout rate,” she said.
“But I also have a high tolerance for a high dropout rate in a group that has the most severe asthma,” she said. “It might not be for everyone, but if it helps a group that needs help, then it’s worth studying further.”
Correction: An earlier version of this story misstated the source of the study.