Autologous Tax-Specific CTL Therapy in a Primary Adult T Cell Leukemia/Lymphoma Cell–Bearing NOD/Shi-scid, IL-2Rγnull Mouse Model

We expanded human T-lymphotropic virus type 1 Tax-specific CTL in vitro from PBMC of three individual adult T cell leukemia/lymphoma (ATL) patients and assessed their therapeutic potential in an in vivo model using NOG mice bearing primary ATL cells from the respective three patients (ATL/NOG). In these mice established with cells from a chronic-type patient, treatment by i.p. injection of autologous Tax-CTL resulted in greater infiltration of CD8-positive T cells into each ATL lesion. This was associated with a significant decrease of ATL cell infiltration into blood, spleen, and liver. Tax-CTL treatment also significantly decreased human soluble IL-2R concentrations in the sera. In another group of ATL/NOG mice, Tax-CTL treatment led to a significant prolongation of survival time. These findings show that Tax-CTL can infiltrate the tumor site, recognize, and kill autologous ATL cells in mice in vivo. In ATL/NOG mice with cells from an acute-type patient, whose postchemotherapeutic remission continued for >18 mo, antitumor efficacy of adoptive Tax-CTL therapy was also observed. However, in ATL/NOG mice from a different acute-type patient, whose ATL relapsed after 6 mo of remission, no efficacy was observed. Thus, although the therapeutic effects were different for different ATL patients, to the best of our knowledge, this is the first report that adoptive therapy with Ag-specific CTL expanded from a cancer patient confers antitumor effects, leading to significant survival benefit for autologous primary cancer cell–bearing mice in vivo. The present study contributes to research on adoptive CTL therapy, which should be applicable to several types of cancer.