Relationship Between Topotecan Systemic Exposure and Tumor Response in Human Neuroblastoma Xenografts

Background: Topotecan is a topoisomerase I inhibitor with activity against xenografts of childhood solid tumors and established clinical activity against neuroblastoma and rhabdomyosarcoma. We have studied the relationship between systemic exposure to and the antitumor activity of topotecan lactone...

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Bibliographic Details
Published in:JNCI : Journal of the National Cancer Institute 1998-04, Vol.90 (7), p.505-511
Main Authors: Zamboni, William C., Stewart, Clinton F., Houghton, Peter J., Thompson, Joyce, Santana, Victor M., Cheshire, Pamela J., Richmond, Lois B., Houghton, Janet A., Luo, Xiaolong, Poquette, Catherine
Format: Article
Language:English
Subjects:
Adrenal Gland Neoplasms - drug therapy
Animals
Antineoplastic Agents - pharmacokinetics
Antineoplastic Agents - pharmacology
Biological and medical sciences
Bone Marrow Neoplasms - drug therapy
Cancer
Dose-Response Relationship, Drug
Drug therapy
Enzyme Inhibitors - pharmacokinetics
Enzyme Inhibitors - pharmacology
Humans
Medical research
Medical sciences
Mice
Mice, Inbred CBA
Neuroblastoma - drug therapy
Neurology
Other treatments
Retroperitoneal Space
Rhabdomyosarcoma - drug therapy
Topoisomerase I Inhibitors
Topotecan - pharmacokinetics
Topotecan - pharmacology
Transplantation, Heterologous
Treatment. General aspects
Tumors
Tumors of the nervous system. Phacomatoses
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Summary:Background: Topotecan is a topoisomerase I inhibitor with activity against xenografts of childhood solid tumors and established clinical activity against neuroblastoma and rhabdomyosarcoma. We have studied the relationship between systemic exposure to and the antitumor activity of topotecan lactone (the active form of the drug) in the xenograft models. Furthermore, we determined whether the responses seen in these models occur at systemic exposure levels that are tolerable in children. Methods: Neuroblastoma xenografts derived from the tumors of six different patients were established subcutaneously in immune-deprived mice. Topotecan was administered by intravenous bolus injection 5 days a week for 2 consecutive weeks, repeated every 21 days for three cycles. The minimum daily doses that induced complete responses (CRs) and partial responses (PRs) were determined. Topotecan lactone pharmacokinetic studies were performed in both tumor-bearing and nontumor-bearing mice. Results: The minimum doses associated with CRs and PRs in four of the six neuroblastoma xenografts were 0.61 and 0.36 mg/kg body weight, respectively. The topotecan lactone single-day systemic exposures associated with these doses were 88 and 52 ng · hr/mL, respectively. There was an approximately sixfold difference in topotecan lactone systemic exposure (290 ng · hr/mL versus 52 ng · hr/mL) associated with achieving CRs in the least-sensitive and mostsensitive tumors, respectively. Conclusions: Neuroblastoma xenografts are highly sensitive to topotecan therapy, and responses in mice are achieved at systemic exposures similar to those that are clinically effective and tolerable in children. These results support the concept of deriving preclinical data relating systemic exposure to antitumor activity in xenograft models. Such data may be valuable in making informed decisions regarding the clinical development of new agents.
ISSN:0027-8874
1460-2105
DOI:10.1093/jnci/90.7.505