Safety and feasibility of convection-enhanced delivery of nimustine hydrochloride co-infused with free gadolinium for real-time monitoring in the primate brain.
OBJECTIVE
Convection-enhanced delivery (CED) has been developed as an effective drug-delivery strategy for brain tumors. Ideally, direct visualization of the tissue distribution of drugs infused by CED would assure successful delivery of therapeutic agents to the brain tumor  while minimizing exposure of the normal brain tissue. We previously showed the anti-tumor efficacy of nimustine hydrochloride (ACNU) delivered via CED against a rodent intracranial xenografted tumor model. Here, we developed a method to monitor the drug distribution using a non-human primate  brain.


METHODS
CED of a mixture of ACNU with gadodiamide was performed using three non-human primates under real-time magnetic resonance imaging monitoring. Animals were clinically observed for any toxicity after infusion. Two months later, their brains were subjected to histological  examination for the evaluation of local toxicity. Another one animal was euthanized immediately after CED of a mixture of ACNU, gadodiamide, and Evans blue dye to evaluate the concordance between ACNU and gadodiamide distributions. The harvested brain was cut into blocks and the ACNU content  was measured.


CONCLUSIONS
Real-time magnetic resonance imaging monitoring of co-infused gadodiamide confirmed the success of the infusion maneuver. In the monkey that also received Evans blue, the distribution of Evans blue was similar to that of gadodiamide and paralleled  the measured ACNU content, suggesting concordance between ACNU and gadodiamide distributions. Histological examination revealed minimum tissue damage with the infusion of ACNU at 1 mg/ml, determined as a safe dose in our previous rodent study. CED of ACNU can be co-administered with gadodiamide  to ensure successful infusion and monitor the distribution volume.
Department of Neurosurgery, Tohoku University Graduate School of Medicine, Sendai, Japan.
Shin-ichiro
S
Sugiyama
Ryuta
R
Saito
Taigen
T
Nakamura
Yoji
Y
Yamashita
Michiko
M
Yokosawa
Yukihiko
Y
Sonoda
Toshihiro
T
Kumabe
Mika
M
Watanabe
Teiji
T
Tominaga
D000818:Animals; D000970:Antineoplastic Agents / Q000008:administration & dosage* / Q000493:pharmacokinetics; D001921:Brain / Q000187:drug effects; D018481:Convection; D016503:Drug Delivery Systems / Q000379:methods*; D005240:Feasibility Studies; D019786:Gadolinium DTPA / Q000008:administration & dosage* / Q000493:pharmacokinetics; D008252:Macaca fascicularis; D008279:Magnetic Resonance Imaging; D008297:Male; D015376:Nimustine / Q000008:administration & dosage* / Q000493:pharmacokinetics; D014018:Tissue Distribution
D000970:Antineoplastic Agents; D015376:Nimustine; C064925:gadodiamide; D019786:Gadolinium DTPA