Autolymphocyte Therapy: III. Effective Adjuvant Adoptive Cellular Therapy with in Vivo Anti-tumor Specificity against Murine Melanoma and Carcinoma Using ex-Vivo-Activated Memory T-Lymphocytes

Abstract

Autolymphocyte therapy (ALT) is adoptive cellular therapy of neoplastic disease based upon ex vivo activation of lymphocytes by either the supernatant derived from a previously prepared one-way mixed lymphocyte culture (MLC) or using low doses of the mitogenic monoclonal antibody OKT3 and a mixture of previously prepared cytokines (T3CS). We have previously demonstrated that nonspecific ex vivo activation of splenocytes from murine tumor-bearing hosts (TBH) using an MLC-supernatant or T3CS without the use of tumor antigen results in the expansion of the CD44 + (memory) T-cell subset. These CD44 + T-cells are the principal mediators of anti-tumor specificity in the ALT-cell population in advanced metastatic murine tumors and are able to protect against tumor challenge in healthy syngeneic mice (HSM). To determine if ALT is effective in an adjuvant setting, C57BL/6J splenocytes from HSM and TBH with B16 melanoma or Lewis lung (3LL) carcinoma were activated ex vivo using T3CS. Mice were implanted with either B16 melanoma or 3LL carcinoma and then underwent surgical excision of tumor. Tumor-excised mice (TEM) then received small numbers (10 6) of ALT-cells derived from 3LL-TBH or B16-TBH splenocytes, HSM-derived ALT-cells, fresh splenocytes derived from 3LL-TBH or B16-TBH, or CD44-depleted ALT-cells. Significant anti-tumor activity as shown by prolonged survival (Day 100), cure of disease, and rejection of a local and systemic tumor rechallenge was demonstrated in 3LL-TEM that received 3LL-derived ALT-cells and in B16-TEM that received B16-derived ALT-cells. TEM that received HSM-derived ALT-cells, fresh TBH-derived splenocytes, or CD44-depleted ALT-cells demonstrated no greater anti-tumor effects than those treated with surgery alone. TEM that received ALT-cells from reciprocal TBH did not have increased survival or cure of disease over TEM treated by surgery alone, but were able to reject challenges of both tumors. These data suggest that effective adjuvant adoptive cellular therapy is possible using small numbers of ex vivo T3CS-activated splenocytes from murine TBH, that the anti-tumor effect is specific and dependent on memory T-cell infusion, and that this strategy may be effective in human patients in the adjuvant setting.