Treatment of Progressive Multifocal Leukoencephalopathy With Third-Party Allogeneic BK Virus T Cells.
Amanda Olson, Ye Li, David Marin et al.
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In 30 seconds
This single-center phase 2 study evaluated third-party, partially HLA-matched BK virus-specific T cells in 37 patients with progressive multifocal leukoencephalopathy (PML), including 23 with hematologic malignancy. During 12 months of follow-up, 21 patients (56.8%) achieved an overall response, defined by virologic response with neurologic stabilization or improvement; 16 (43.2%) had a complete response or complete response with neurologic sequelae. Responses occurred at a median of 23 days. The 1-year overall survival was 61.1% (95% CI, 41.9-77.4).
Key findings
- Overall response occurred in 21 patients (56.8%); 16 (43.2%) achieved complete response or complete response with neurologic sequelae.
- Responses occurred at a median of 23 days and were durable, with no observed loss of response during follow-up.
- One-year overall survival was 61.1% (95% CI, 41.9-77.4).
- Among patients responding after the first infusion, 1-year survival was 93.3% vs 0% in nonresponders (P < .001); greater HLA matching correlated with clinical benefit.
Why it matters
PML has no approved therapy and is often fatal, making these findings relevant to the search for immune-based treatment options. The observed virologic and neurologic responses, alongside survival outcomes, suggest that partially HLA-matched, off-the-shelf BK virus-specific T cells may offer a scalable approach. The results remain preliminary and should be interpreted in light of the study design.
What to keep in mind
The study was single-center and included 3 patients treated under compassionate or emergency INDs; it does not establish comparative efficacy.