Human peripheral blood γδ T cells can recognize and kill tumor cells by their Vγ9Vδ2 T cell receptor and/or NKG2D. We have established large-scale ex vivo expansion of γδ T cells from peripheral blood mononuclear cells (PBMC) by zoledronate and IL-2. A clinical study of adoptive γδ T cell transfer therapy has been conducted for the treatment of non-small-cell lung cancer (NSCLC) patients to evaluate the safety profile and potential anti-tumor effects of γδ T cells. Prior to beginning the study, it was registered on a University hospital Medical Information Network Clinical Trials Registry (UMIN-CTR : http://www.umin.ac.jp/ctr/index.htm) on March 1, 2006 (UMIN ID: C00000036).

PBMC were isolated from 67.5 ml of peripheral blood and stimulated with zoledronateand IL-2 for 14 days to obtain γδ T cells. The cultured cells on day 14 consisted mostly of γδ T cells. The predominant populations in fresh peripheral blood were cells with the CD45RACD27+ memory phenotype or a CD45RA+CD27 naïve phenotype. In contrast, most γδ T cells were shown to have the CD45RACD27 effector memory phenotype after 14 days culture. They expressed NKG2D and up-regulated the expression of activation marker CD69, and had cytotoxicity against allogeneic tumor cell lines. Upon stimulation, γδ T cells produced IL-2, TNF-α and IFN-γ. Though certain patients were refractory to zoledronate stimulation, γδ T cells from patients demonstrated comparable cytotoxic effector activity once they were successfully expanded.

Cultured cells were intravenously administered every 2 weeks for 6 injections. Fifteen patients who were resistant to current standard therapy were enrolled this study. The treatment was well tolerated and no severe adverse events related to γδ T cell therapy were observed. Two patients came off the study at the early stage of the treatment due to the aspiration pneumonia (grade 3) and radiation pneumonitis (grade3). The responses according to RECIST guideline were SD for 7 patients, PD for 6 patients and 2 inevaluable for response due to early drop off the study (The disease control rate was 46.7 %).

Transferred γδ T cells gradually accumulated in peripheral blood in patients who received more than 1×109 γδ T cells per injection and accounted for 10 % of PBMC even 2 weeks after the final injection. When PBMC were stimulated with PMA/ionomycin or zoledronate-pulsed Daudi cells, IFN-γ production and surface expression of CD107 were detected on γδ T cells, suggesting that transferred γδ T cells sustained their effector function in vivo.

These results indicated that γδ T cell therapy was well tolerated and feasible for the treatment of NSCLC.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1926.