This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Wickström, M. Articles by Gullbo, J. Search for Related Content PubMed PubMed Citation Articles by Wickström, M. Articles by Gullbo, J.

Research Articles: Therapeutics, Targets, and Development

The novel melphalan prodrug J1 inhibits neuroblastoma growth in vitro and in vivo

¹ Division of Clinical Pharmacology, Department of Medical Sciences, Uppsala University, Uppsala, Sweden; ² Childhood Cancer Research Unit, Departments of Woman and Child Health, and ³ Oncology-Pathology, Karolinska Biomics Center, Karolinska Institutet, Stockholm, Sweden; and ⁴ Division of Clinical Pharmacology, Department of Medicine and Care, Faculty of Health Sciences, Linkoping University, Linkoping, Sweden

Requests for reprints: Malin Wickström, Division of Clinical Pharmacology, Department of Medical Sciences, Entrance 61, 4th Floor Uppsala University Hospital, 75185 Uppsala, Sweden. Phone: 46-18-6112931; Fax: 46-18-519237. E-mail: Malin.Wickstrom{at}medsci.uu.se

Abstract

Neuroblastoma is the most common extracranial solid tumor of childhood. The activity of J1 (L-melphalanyl-p-L-fluorophenylalanine ethyl ester), an enzymatically activated melphalan prodrug, was evaluated in neuroblastoma models in vitro and in vivo. Seven neuroblastoma cell lines with various levels of drug resistance were screened for cytotoxicity of J1 alone or in combination with standard cytotoxic drugs, using a fluorometric cytotoxicity assay. J1 displayed high cytotoxic activity in vitro against all neuroblastoma cell lines, with IC₅₀ values in the submicromolar range, significantly more potent than melphalan. The cytotoxicity of J1, but not melphalan, could be significantly inhibited by the aminopeptidase inhibitor bestatin. J1 induced caspase-3 cleavage and apoptotic morphology, had additive effects in combination with doxorubicin, cyclophosphamide, carboplatin, and vincristine, and synergistically killed otherwise drug-resistant cells when combined with etoposide. Athymic rats and mice carrying neuroblastoma xenografts [SH-SY5Y, SK-N-BE(2)] were treated with equimolar doses of melphalan, J1, or no drug, and effects on tumor growth and tissue morphology were analyzed. Tumor growth in vivo was significantly inhibited by J1 compared with untreated controls. Compared with melphalan, J1 more effectively inhibited the growth of mice with SH-SY5Y xenografts, was associated with higher caspase-3 activation, fewer proliferating tumor cells, and significantly decreased mean vascular density. In conclusion, the melphalan prodrug J1 is highly active in models of neuroblastoma in vitro and in vivo, encouraging further clinical development in this patient group. [Mol Cancer Ther 2007;6(9):2409–17]

Grant support: The Swedish Children's Cancer Foundation, the European Commission (contract no. QLK3-CT-2002-01956), and the Lions Cancer Research Fund.

The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

⁵ Unpublished data.

⁶ Unpublished data, estimation in Sprague-Dawley rats.

⁷ Unpublished data, estimation in specific pathogen–free Swiss mice.

⁸ Wickström et al., unpublished observation.

⁹ Unpublished data.

Received 3/ 6/07; revised 5/29/07; accepted 7/ 6/07.