Anti-tumor activity and immunogenicity of a mutated staphylococcal enterotoxin C2

In this study, a novel SEC2 mutant with lower toxic activity, named 2M-118 (H118A/T20L/G22E), was engineered by site-directed mutagenesis of structural domains that are responsible for MHC class II molecule binding and TCR binding, respectively. Stimulating activity on murine splenocytes, anti-tumor effect and immunogenicity of 2M-118 were investigated in BALB/c mice. 2M-118 not only remained splenocyte stimulation activity, but also effectively inhibited the growth of S180 sarcoma in the BALB/c mice. Even though antibodies to 2M-118 could be induced after repeated administration, the action of 2M-118 was hardly neutralized or cross neutralized. Like other superantigens, immunosuppression could happen when 2M-118 was given at a greater dose. In conclusion, 2M-118 is a promising anti-tumor drug candidate for its acceptable toxicity and satisfying anti-tumour efficacy.