A Cancer Drug For Parkinson's? New Study Raises Hope, Draws Criticism

Dec 16, 2019
Originally published on December 16, 2019 11:26 pm

A leukemia drug may have cleared another hurdle as a potential treatment for Parkinson's disease.

But critics say it's still not clear whether the drug, nilotinib (brand name Tasigna), is truly safe or effective for this use.

In a study of 75 people with Parkinson's, nilotinib appeared to improve quality of life and boost the chemical dopamine, a team from Georgetown University Medical Center reported Monday in JAMA Neurology.

"We are seeing signals that this may be a potential treatment for our Parkinson's disease patients," says Dr. Fernando Pagan, director of the medical center's movement disorders program.

But other scientists are less positive about the results.

"They really didn't find anything convincing," says Dr. Joel Perlmutter, who directs the movement disorders program at Washington University School of Medicine in St. Louis.

Parkinson's is a nervous system disorder that causes movement problems including stiffness and tremors. Existing drugs can treat those symptoms, but not the underlying loss of brain cells that causes the disease.

Several years ago, a team at Georgetown began studying nilotinib as a way to treat Parkinson's and other brain diseases, including Alzheimer's.

The drug appears to help brain cells clear out toxic substances that build up in those diseases.

When patients take nilotinib, "You turn on the garbage disposal daily and you're able to get rid of that accumulation and hopefully see better function," Pagan says.

Results of a small, preliminary study looked promising. So the Georgetown team launched the larger, more rigorous second-phase study of 75 people.

In the new study, some Parkinson's patients took either 150 milligrams or 300 milligrams of nilotinib each day for a year, while others received a placebo.

The results suggest that the drug is reasonably safe for these patients and may even be slowing down the disease, Pagan says.

Samples of spinal fluid showed that patients who got the 150-milligram dose of the drug had lower levels of a toxic form of the protein alpha synuclein, which tends to build up in people with Parkinson's.

The study also found some evidence that nilotinib raised levels of dopamine, the brain chemical that is lacking in people with Parkinson's.

"Nilotinib is increasing the availability of stored dopamine in the brain," says Charbel Moussa, scientific and clinical research director of the translational neurotherapeutics program at Georgetown University. "So the brain is now extracting its own endogenous stores of dopamine."

Perlmutter isn't so sure.

It's not clear from the study whether the dopamine changes were caused by nilotinib or something else, he says. And other seemingly positive results looked good at one point in time but not in another.

"It's possible these are really statistical aberrations and are not really convincing evidence of a change induced by the drug," he says. "But we don't know."

Perlmutter is also concerned about side effects, including heart problems, which were more frequent in people who got the drug than those who got a placebo. Nilotinib is known to cause heart problems in some leukemia patients.

The Georgetown study represents the latest exchange in an ugly scientific conflict over the use of nilotinib for Parkinson's.

The Michael J. Fox Foundation for Parkinson's Research has publicly criticized the Georgetown research — even as it was conducting its own study of the drug.

And a week ago, the foundation put out a press release saying that nilotinib didn't help Parkinson's patients in their study — even though results of that study haven't been published.

Moussa, who holds a patent on the use of nilotinib for treating brain diseases, says patients should ignore the scientific infighting.

"This may fail. It's OK," he says. "But I think the concept is very feasible and if this drug doesn't work, another drug will work."

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ARI SHAPIRO, HOST:

Researchers say a cancer drug has cleared another hurdle as a potential treatment for Parkinson's disease. If the drug succeeds, it would be the first to slow down Parkinson's rather than just reducing its symptoms. NPR's Jon Hamilton reports skeptics still have doubts about the unusual treatment.

JON HAMILTON, BYLINE: The drug is called nilotinib, and it's used for a type of leukemia. But a team at Georgetown University Medical Center has been studying nilotinib as a way to treat Parkinson's and other brain diseases. Dr. Fernando Pagan says it works like a garbage disposal to clear out toxic substances that build up in brain cells.

FERNANDO PAGAN: You turn on the garbage disposal daily, and you're able to get rid of that accumulation and hopefully see better function.

HAMILTON: Preliminary results looked encouraging, so the team launched a study of 75 Parkinson's patients. Some got relatively low doses of nilotinib, which is sold under the brand name Tasigna. Others got a placebo. Pagan says the results show that the drug is reasonably safe for these patients and may even be slowing down the disease.

PAGAN: This drug is still not ready for prime time. I think there's still a lot more work to be done, but we are seeing signals that this may be a potential treatment for our Parkinson's patients.

HAMILTON: Patients who got the drug had lower levels of two toxic substances in their spinal fluid. They also reported a better quality of life. And Georgetown's Charbel Moussa says the drug seemed to increase dopamine, the brain chemical that is lacking in people with Parkinson's.

CHARBEL MOUSSA: Nilotinib is increasing the availability of the stored dopamine in the brain. So the brain is now extracting its own endogenous stores of dopamine.

HAMILTON: The results appear in the journal JAMA Neurology, and they represent the latest exchange in an ugly scientific conflict over the use of nilotinib for Parkinson's. The Michael J. Fox Foundation for Parkinson's Research has publicly criticized the Georgetown research, even as it was conducting its own study of the drug. And earlier this month, the foundation announced that nilotinib didn't help Parkinson's patients in their study, even though the study results hadn't been published.

Moussa, who holds a patent on the use of nilotinib for treating brain diseases, says patients should ignore the scientific infighting.

MOUSSA: This may fail. It's OK. But I think the concept is very feasible. And if this drug doesn't work, another drug will work.

HAMILTON: But scientists, including Dr. Joel Perlmutter of Washington University in St. Louis, have doubts about the study.

JOEL PERLMUTTER: They really didn't find anything convincing.

HAMILTON: Perlmutter says some results look good at one time point, but not another. And he says it's not clear whether the dopamine changes were caused by nilotinib.

PERLMUTTER: It's possible these are really statistical aberrations and are not really convincing evidence of a change induced by the drug. But we don't know.

HAMILTON: Perlmutter says he's also concerned about side effects, which were more frequent in people who got the drug. He says it will take a much larger study to show whether nilotinib really can help people with Parkinson's.

Jon Hamilton, NPR News. Transcript provided by NPR, Copyright NPR.