Suicide gene therapy for plasma cell tumors

Suicide gene therapy for plasma cell tumors was attempted in severe combined immunodeficient (SCID) mice injected with human myeloma cell lines, initially, a ganciclovir-induced bystander effect was observed in vitro using myeloma cells transduced with a herpes simplex thymidine kinase (HSVtk) gene. Transduced cells injected subcuteanously (SC) into SCID mice could be eradicated by the administration of ganciclovir (GCV). Furthermore, an in vivo bystander effect was noticed when mice received mixtures of HSVtk-positive and nontransduced cells, Unexpectedly, a ''distant by-stander'' effect was observed as tumors in regions inoculated with only nontransduced cells were significantly smaller and had increased frequency of apoptotic figures and decreased mitotic frequency in GCV-treated mice transplanted with HSVtk-positive cells at a different region compared with control mice. (C) 1996 by The American Society of Hematology.