BACKGROUND: MYCN-amplification in high-grade Neuroblastoma (NB) tumors correlates with increased vascularization and therapy resistance. This study combines an anti-angiogenic approach with targeting NB metabolism for treatment.
METHODS AND RESULTS: Metronomic cyclophosphamide (MCP) monotherapy significantly inhibited NB growth and prolonged host survival. Growth inhibition was more pronounced in MYCN-amplified xenografts. Immunohistochemical evaluation of this subtype showed significant decrease in blood vessel density and intratumoral hemorrhage accompanied by blood vessel maturation and perivascular fibrosis. Up-regulation of VEGFA was not sufficient to compensate for the effects of the MCP regimen. Reduced Bcl-2 expression and increased caspase-3 cleavage were evident. In contrast non MYCN-amplified tumors developed resistance, which was accompanied by Bcl-2-up-regulation. Combining MCP with a ketogenic diet and/or calorie-restriction significantly enhanced the anti-tumor effect. Calorie-restricted ketogenic diet in combination with MCP resulted in tumor regression in all cases.
CONCLUSIONS: Our data show efficacy of combining an anti-angiogenic cyclophosphamide dosing regimen with dietary intervention in a preclinical NB model. These findings might open a new front in NB treatment.