Allogeneic bone marrow transplantation, through donor lymphocyte infusion (DLI), is commonly used in the treatment of leukemia and lymphoma. Although it is an effective therapy, graft versus host disease is seen in 30-50% of patients. This side-effect is the result of transplanted T cells from the donor attacking normal tissue as well as the target leukemia or lymphoma cells. GVHD is difficult to treat and has a mortality rate of 15-30%. As few treatment options are available, this represents a disease with high unmet therapeutic need.

LG690 is a T cell therapy where T cells are removed from a donor and treated ex vivo with a lentiviral vector expressing a safety payload called TMPK. Treated cells are then reinfused into the patient as part of the transplantation process. In those patients who do not develop GVHD, the safety gene remains inactivated. In those patients who develop GVHD the safety gene can be activated through the administration of azidothymidine (AZT, Retrovir®), eliminating the T cells that are provoking the GVHD response.

LG690 is scheduled to begin phase I clinical trials in 2010 at the National Cancer Institute in Bethesda, Maryland and at the Medical College of Wisconsin in Milwaukee, Wisconsin. Information on the clinical trial can be found here.