Development of herpes simplex virus-1 amplicon-based immunotherapy for chronic lymphocytic leukemia

Herpes simplex virus (HSV)-based vectors have favorable biologic features f or gene therapy of leukemia and lymphoma. These include high transduction e fficiency, ability to infect postmitotic cells, and large packaging capacit y, The usefulness of HSV amplicon vectors for the transduction of primary h uman B-cell chronic lymphocytic leukemia (CLL) was explored. Vectors were c onstructed encoding beta -galactosidase (LacZ), CD80 (B7.1), or CD154 (CD40 L) and were packaged using either a standard helper virus (HSVlac, HSVB7.1, and HSVCD40L) or a helper virus-free method (hf-HSVlac, hf-HSVB7.1 and hf- HSVCD40L), Both helper-containing and helper-free vector stocks Introductio n were studied for their ability to transduce CLL cells, up-regulate costim ulatory molecules, stimulate allogeneic T-cell proliferation in a mixed lym phocyte tumor reaction, and generate autologous cytotoxic T lymphocytes (CT Ls), Although helper-containing and helper-free amplicon stocks were equiva lent in their ability to transduce CLL cells, a vigorous T-cell proliferati ve response was obtained using cells transduced with hf-HSVB7.1 but not wit h HSVB7.1, CLL cells transduced with either HSVCD40L or hf-HSVCD40L were co mpared for their ability to upregulate resident B7.1 and to function as T-c ell stimulators. Significantly enhanced B7.1 expression in response to CD40 L was observed using hf-HSVCD40L but not with HSVCD40L, CLL cells transduce d with hf-HSVCD40L were also more effective at stimulating T-cell prolifera tion than those transduced with HSVCD40L stocks and were successful in stim ulating autologous CTL activity, It is concluded that HSV amplicons are eff icient vectors for gene therapy of hematologic malignancies and that helper virus-free HSV amplicon preparations are better suited for immunotherapy. (C) 2001 by The American Society of Hematology.