ABC drug transporter gene expression in neuroblastoma.

9524 Background: In advanced neuroblastoma (NB), resistance to cytotoxics is the main cause of therapeutic failure and poor outcome. A distinctive type of resistance, multidrug resistance (MDR), is associated with increased ABC drug transporter expression. ABCB1 (MDR1), ABCC1 (MRP1) and ABCC4 (MRP4) are expressed in NB, but their impact on therapeutic response and outcome is unclear. Nothing is known on ABCG2, a major player in MDR. We investigated ABCB1, ABCC1/4 and ABCG2 gene expression in NB tumors. Methods: Untreated primary NB samples were obtained from 109 pts aged 1 d to 199 mos (median, 32 mos), staged according to INSS: 36 stage 1, 2 or 4S; and 73 stage 3 or 4. MYCN amplification (MNA) was found in 18/109 NBs (17%). Stage 3/4 pts were given induction chemotherapy including cyclophosphamide, doxorubicin, vincristine, cisplatin, carboplatin or etoposide. No selection criteria were applied for study except for the availability of frozen tumor tissue. Institutional written informed consent and ethica...