Herpes simplex thymidine kinase (HStk) transgenic donor lymphocytes

Patients with recurrent leukemia after an allogeneic hematopoietic stem cel l transplant may be treated with donor lymphocyte infusions (DLI), The tran sfusion of lymphocytes from the original hematopoietic stem cell donor indu ces remission in approximately one third of relapsed AML cases and 80% of r elapsed CML, DLI may be complicated by delayed and sometimes lethal graft-v ersus-host disease (GVHD), In an attempt to avoid this complication, severa l centers have initiated DLI trials in which the infused lymphocytes carry a suicide gene, herpes simplex thymidine kinase (HStk), which confers sensi tivity to ganciclovir (GCV), In the event of severe GVHD, administration of GCV should terminate or ameliorate GVHD.