Paclitaxel: an effective antineoplastic agent in the treatment of xenotransplanted hepatoblastoma

Hepatoblastoma is an uncommon liver tumor of infancy and early childhood. Though most patients with nonmetastatic hepatoblastomas can be cured by defining surgical strategies and chemotherapy regimes, new drugs are needed for children with advanced hepatoblastomas. The activity of paclitaxel as a new antineoplastic agent with limited experience in pediatric oncology was studied in a xenograft model.

Hepatoblastoma cell suspensions from three children were transplanted subcutaneously into nude mice NMRI (nu/nu). One of the primary tumors was an embryonal multifocal hepatoblastoma, whereas the other tumors were embryonal/fetal hepatoblastomas localized on a liver lobe. After 4 weeks, xenografted tumor sizes reached 50-100 mm3. The xenografted tumors resembled their originals histologically and produced high levels of alpha-fetoprotein. The efficiency of paclitaxel at equitoxic doses was analyzed.

Paclitaxel produced an effect in all three hepatoblastomas. There was a significant reduction of tumor volume (P < 0.001) and alpha-fetoprotein levels after chemotherapy (P < 0.0001). The proliferation activity of the tumor cells corresponded with these results. Histologically, after treatment with paclitaxel the tumor regression was 35%-49%. The mechanism of paclitaxel action could be demonstrated by light microscopy immunohistochemistry and electron microscopy.

The preliminary results in phase I trials of solid tumors in children and the results of this study suggest that paclitaxel in phase II studies can now be entertained for patients with hepatoblastoma.