Purpose: Human Vα24 natural killer T (Vα24 NKT) cells bearing an invariant Vα24JαQ antigen receptor are activated by a glicolipid ligand α-galactosylceramide (αGalCer; KRN7000) in a CD1d-dependent manner. The human Vα24 NKT cells activated with αGalCer and interleukin-2 have been shown to produce large amounts of cytokines, such as IFN-γ, and also exerting a potent killing activity against various tumor cell lines. We did a phase I study with autologous activated Vα24 NKT cell therapy.

Experimental Design: Patients with advanced or recurrent non–small cell lung cancer received i.v. injections of activated Vα24 NKT cells (level 1: 1 × 10⁷/m² and level 2: 5 × 10⁷/m²) to test the safety, feasibility, and clinical response of this therapeutic strategy. Immunomonitoring was also done in all cases.

Results: Six patients were enrolled in this study. No severe adverse events were observed during this study in any patients. After the first and second injection of activated Vα24 NKT cells, an increased number of peripheral blood Vα24 NKT cells was observed in two of three cases receiving a level 2 dose of activated Vα24 NKT cells. The number of IFN-γ-producing cells in peripheral blood mononuclear cells increased after the administration of activated Vα24 NKT cells in all three cases receiving the level 2 dose. No patient was found to meet the criteria for either a partial or a complete response.

Conclusions: The clinical trial with activated Vα24 NKT cell administration was well tolerated and carried out safely with minor adverse events even in patients with advanced diseases.