RECOMBINANT VACCINIA EXPRESSING INTERLEUKIN-2 FOR CANCER GENE-THERAPY

Use of a recombinant vaccinia virus expressing human interleukin-2 (IL -2) was evaluated for preparation of tumor vaccines. A/J mice were imm unized against neuroblastoma (C1300) cells using a preparation of C130 0 cells infected/transfected with the recombinant virus, vCF13, expres sing IL-2. A second recombinant vaccinia, vSC8, expressing Escherichia coli P-galactosidase, was used as a control. After three weekly immun izations with virus-transfected cells, the mice were challenged with 1 x 10(6) unmodified C1300 cells and tumor development was monitored. T umor development in the mice was inhibited by immunization with vCF13- transfected cells, compared to those vaccinated with vSC8-transfected cells (P <.008). A group of mice (7/15) immunized with vCF13-transfect ed cells followed by tumor challenge survived more than 60 days, at wh ich time all mice immunized with the control vaccine were dead (p <.00 6). Five of the mice treated with the vCF13 vaccine were alive for mor e than 75 days (P <.05), after which they were rechallenged with anoth er dose of 1 x 10(6) unmodified tumor cells. Tumor development was not apparent in these mice for more than 45 days following the second cha llenge, suggesting that these mice were completely protected by this i mmunization. These results demonstrate that recombinant vaccinia virus expressing IL-2 may be useful for cancer gene therapy.