Adoptive immunotherapy of poorly immunogenic tumors with in vitro sensitized cells generated by intratumoral administration of biological response modifiers

Abstract We investigated the efficacy of intratumoral administration of biological response modifiers (BRM) in induction of in vitro sensitized (IVS) cells for adoptive immunotherapy of the poorly immunogenic MCA 102 sarcoma and B16-BL6 (BL6) melanoma. We used the bacterial immunoadjuvant Nocardia rubra cell wall skeleton (N-CWS), and a streptococcal preparation, OK-432, for MCA 102 and BL6, respectively. After C57BL/6 (B6) mice were inoculated subcutaneously (s.c.) with viable MCA 102 or BL6 tumor cells in the foot-pad, mice were injected intratumorally (i.t.) with N-CWS ranging from 10 to 400 gg or OK-432 ranging from 1 to 100 μg. Draining popliteal lymph nodes (LN) were harvested 7 days after i.t. administration of BRM, and LN cells were cultured with irradiated tumor cells in the presence of IL-2 for 11 days. These IVS cells (7.5 × 10 6 or 2 × 10 6 ) were transferred intravenously (i.v.) to B6 mice with 4 day pulmonary metastases established by i.v. injection of viable MCA 102 cells (1 × 10 6 ) or viable BL6 cells (3 × 10 5 ). The mice were also received intraperitoneally 4 × 10 4 IU/day of IL-2 for 4 days after adoptive transfer. The transfer of IVS cells from mice immunized by i.t. injection of 100 μg of N-CWS 1 week after inoculation of tumor cells significantly reduced MCA 102 pulmonary metastases, compared with control IVS cells without administration of N-CWS. Moreover, the transfer of IVS cells from mice immunized by i.t. injection of 10 gg of OK-432 3 days after inoculation of tumor cells significantly reduced BL6 pulmonary metastases compared with control IVS cells without administration of OK-432. The administration of N-CWS resulted in no enhancement of in vitro cytotoxicity. Although the administration of 10 gg of OK-432 augmented in vitro cytotoxicity of 1VS cells against BL6, cytotoxic activity was lower than that of IVS cells immunized with N-CWS. The major phenotype was CD8 + cells in IVS cells immunized with N-CWS or OK-432. These results suggest that i.t. administration of N-CWS and OK-432 facilitates the production of sensitized T-cells, and this administration route of BRM may be useful in the adoptive immunotherapy of human cancer.