Novel Cell Therapy Offers Promise for Deadly Brain Infection

(Bloomberg) -- Medical researchers are making progress against a rare and deadly brain infection with the help of cells they cultivated in a laboratory to destroy the virus.

Three patients with the condition known as progressive multifocal leukoencephalopathy, or PML, were successfully treated with living cells taken from healthy donors and grown specifically to fight the infection. The results are published in the New England Journal of Medicine.

The approach is novel for two reasons. It’s the first time any therapy has been effective against the brain-wasting disease, a condition caused by a virus that can lay dormant in people until their immune systems are weakened by conditions like HIV or medicines used to treat cancer, multiple sclerosis or rheumatoid arthritis. It also is off-the-shelf, meaning built in advance so patients can be treated within 24 hours of diagnosis. Many existing cell therapies are created for each patient in a process that can take weeks.

“This is cell therapy, using the immune system to treat a potentially fatal infection that probably has a worse prognosis than most cancers,” said lead researcher Katy Rezvani, professor in the department of stem cell transplantation and cellular therapy at MD Anderson Cancer Center in Houston. “We can’t guarantee that everyone will respond, but in those patients who have received treatment, the results have been amazing.”

One of the patients was a 32-year-old woman who had been treated months earlier for leukemia with a cord blood transplant. She was cured of the cancer but now suffered from PML. She was unable to stand or speak clearly.

After a single injection, her neurological symptoms cleared. She walked out of the hospital three weeks later. After a second and third infusion, given a month apart, the virus and all signs of the PML condition were gone.

Resume Walking

Another patient, a 35-year-old man with AIDS, was carried in on a stretcher because his body couldn’t handle his weight while sitting. His mother had contacted MD Anderson asking about the experimental program, months after he was diagnosed with PML and years after he stopped aggressive HIV treatment because of the side effects. After four infusions, the virus was cleared and he was able to resume walking with a cane.

The final patient was a 73-year-old woman with a blood disorder who was treated with Incyte Corp.’s Jakafi for eight years. She was diagnosed with PML after six months of increasing confusion, problems speaking and understanding, blurred vision and lack of coordination that can make suffers seem like they are drunk.

While the first infusion decreased the amount of virus in her body and her symptoms no longer worsened, she didn’t improve and sought out hospice care. She died eight months after her first infusion.

Sooner the Better

The sooner patients are treated, the more likely the therapy will be successful, Rezvani said. “Often once the damage is present, they can’t recover. The brain is not good at healing itself.”

The findings may offer comfort to patients who take medicine, such as Biogen Inc.’s Tysabri, for multiple sclerosis, that can increase the risk of activating the virus. Those patients are tested for the virus before they begin Tysabri, and those who are positive are told to stop after two years.

To make the therapy, the researchers took healthy infection-fighting T cells from 27 patients and grew them in a culture with antigens that primed them to fight a virus very similar to the one that causes PML. Additional work is needed to confirm the findings and determine if it can help those who had different risk factors for acquiring the PML condition.

Other questions remain. It’s not clear, for instance, whether the infused cells will be rejected as foreign in patients with stronger immune systems.

For patients who do respond, Rezvani said, the results have been dramatic and show another area where cellular therapies may hold lifesaving benefits for patients.

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