C4 treatment decreased SK-N-BE(2) xenograft tumor growth. A nude mouse model was employed to study the in vivo effects of C4 treatment upon neuroblastoma xenografts. SK-N-AS and SK-N-BE(2) neuroblastoma cells were injected into the right flank of nude mice. Once the tumors became palpable (Day 0), the animals were randomized and treated daily with intraperitoneal injections of vehicle (sterile normal saline, n = 10) or C4 (60 mg/kg/dose, n = 10) and tumor volumes were measured twice weekly with calipers. (A) Treatment of the SK-N-AS xenografts with C4 decreased tumor growth, but it did not reach statistical significance. (B) C4 treatment of the SK-N-BE(2) xenografts significantly decreased the growth of the tumors. At the time of euthanasia, the tumors were harvested and weighed. In the SK-N-AS xenografts, the C4 treated tumors tended to weigh less than the saline treated controls, but did not reach statistical significance (C). In the animals with SK-N-BE(2) xenografts, the weights of the tumors treated with C4 were significantly decreased when compared to the xenografts treated with saline (D).