LB-DTK-BKV

The goal of this clinical trial is to assess efficacy of BK virus specific T cells (LB-DTK-BKV) to treat pediatric, adolescent, and adult patients with BK virus-associated hemorrhagic cystitis after allogenic hematopoietic stem cell transplantation (allo-HSCT). It will also evaluate the safety of LB-DTK-BKV using treatment-emergent adverse events (TEAEs). The main questions it aims to answer are:
* Does LB-DTK-BKV reduce the number of BV virus viral load in allo-HSCT patients with hemorrhagic cystitis?
* Do adverse events occur after the second dose? Researchers will compare LB-DTK-BKV to a placebo to see if LB-DTK-BKV works to treat hemorrhagic cystitis in allo-HSCT patients.
Participants will:
* Receive a single intravenous infusion of LB-DTK-BKV (low dose: 1x10^7/m^2; high dose: 2x10^7/m^2).
* Receive the second dose of LB-DTK-BKV intravenously at the same dose 14 days after the first dose.
* Visit the clinic every week for follow-up for 6 months after the first dose.