Could donor cells beat a deadly brain virus?

NCT ID NCT02694783

First seen Jun 25, 2026 · Last updated Jul 17, 2026 · Updated 7 times

Summary

This early-phase study tested whether infusing virus-fighting immune cells from a healthy donor could safely treat progressive multifocal leukoencephalopathy (PML), a serious brain infection in people with weak immune systems. Sixty adults with PML received up to three infusions of these specially grown cells. The main goal was to check safety and feasibility, with researchers also tracking changes in brain lesions and disability over time.

What this could mean

Our plain-language read of the trial. This is informational only — not medical advice or a prediction.

Active substance
virus-specific T cells from a healthy donor
What this could lead to
If it works, this could offer a treatment for PML, a rare and often fatal brain infection, by boosting the immune system to fight the virus.
What could go wrong
This is a very early, small pilot study focused on safety, not yet proven to work. The cells come from a matched donor, which limits availability, and there are risks like infusion reactions or the cells not controlling the infection.

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Conditions

The condition(s) this trial relates to.

As listed by the trial registrant

The condition terms exactly as the trial's registrant entered them.

Contacts and locations

Locations

  • National Institutes of Health Clinical Center

    Bethesda, Maryland, 20892, United States

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