Growth patterns of human neuroblastoma xenografts and their relationship to treatment outcome

Several investigators have reported the ability to establish xenografts in nude mice from children with neuroblastomas, but a correlation of prognosis with this establishment and the growth patterns of the neuroblastomas has not been reported.

Tumor specimens from 58 children with neuroblastomas were heterotransplanted into BALB/c nude mice. In 34 patients, heterotransplantation was done before therapy; in 24 patients, tumors were obtained after at least one course of chemotherapy or radiation therapy. The histology, cytogenetics, and growth characteristics of serial passages of the xenografts were studied.

The engraftment rate was 34%. Neuroblastomas with diploid chromosome numbers did not engraft. Chromosomal abnormalities involving 1p were seen in more than 50% of the xenografts. Cytogenetic features were retained between original tumors and resultant xenografts. Xenografts could be established only from tumors with unfavorable histology, as defined by Shimada classification criteria. The histology of each xenograft line was strikingly similar, and each was highly undifferentiated. Engraftment rates, doubling times, and lag times did not vary appreciably between xenografts established from treated tumors compared with xenografts established from untreated tumors. There was no correlation between doubling or lag times and prognosis. Patients whose tumors engrafted had only a 5% 3-year survival rate.

From these results, it appears that successful engraftment is the most important prognostic indicator for patients with neuroblastomas. Because of the commonality of the histologic features and the stability of the tumor clones from patients before and after heterotransplantation, these xenografts may be useful as an in vivo model for studying drug resistance and for designing treatment regimens.