Cisplatin tumor concentrations after intra-arterial cisplatin infusion or embolization in patients with oral cancer Background: One neoadjuvant course of intra-arterial high-dose cisplatin (cis-diamminedichloroplatinum [CDDP]) tumor perfusion combined with intravenous sodium thiosulfate (STS) (cisplatin neutralizer) infusion is part of a multimodality concept for treatment of oral cancer. Recently, crystalline cisplatin embolization has been described as a novel treatment variant with increased tumor response rates. Methods: We have compared tumor and plasma concentrations of cisplatin and STS by means of microdialysis in 10 patients with oral cancer treated with intra-arterial cisplatin perfusion (150 mg/m 2 in 500 mL of 0.9% sodium chloride) and 6 patients with oral cancer treated with crystalline cisplatin embolization (150 mg/m 2 in 45-60 mL of 0.9% sodium chloride), respectively. The microdialysis catheter was placed into the tumor, and the intra-arterial catheter into the tumor-feeding artery. Cisplatin was rapidly administered through the intra-arterial catheter and STS (9 g/m 2 ) was infused intravenously to reduce the systemic toxicity of cisplatin. STS infusion was started 10 seconds after the cisplatin infusion was started. Results: After embolization, cisplatin tumor maximum concentration (C max ) and tumor area under the concentration-time curves (AUCs) were about 5 times higher than those achieved after intra-arterial perfu- sion (C max , 180.3 62.3 mol/L versus 37.6 8.9 mol/L), whereas the opposite was true for plasma concentrations (C max , 0.9 0.2 mol/L versus 4.7 0.6 mol/L). STS plasma levels were about 3 times higher than its tumor concentrations (C max tumor, 1685 151 mol/L; C max plasma, 5051 381 mol/L). After the standard intra-arterial perfusion, the average STS/CDDP AUC ratios for tumor and plasma were 211 75 and 984 139, respectively. After cisplatin embolization, the respective ratios were 48.5 29.5 and 42,966 26,728. Conclusion: Molar STS/CDDP ratios of greater than 500 are required outside the tumor to neutralize cisplatin, whereas tumor ratios should be lower than 100 to avoid a loss of tumor cell killing. The first goal is achieved with both treatment modalities and the second only with cisplatin embolization, suggesting that crystalline cisplatin embolization is superior to intra-arterial cisplatin perfusion in terms of tumor cisplatin concentrations. Whether this translates into higher tumor response rates needs to be investigated further. (Clin Pharmacol Ther 2003;73:417-26.) Irmgard Tegeder, MD, Lutz Bra ¨utigam, BS, Maic Seegel, Ahmed Al-Dam, Bernd Turowski, MD, Gerd Geisslinger, MD, PhD, and Adorja ´n F. Kova ´cs, MD, DMD Frankfurt am Main, Germany Neoadjuvant intra-arterial (IA) chemotherapy with cisplatin (cis-diamminedichloroplatinum [CDDP]) has been successfully used as part of a multimodality ther- apy for all stages of primary squamous cell carcinoma of the oral cavity. 1-4 The selection of the IA route for the administration of cisplatin is based on the premise that this approach should result in greater total drug exposure for the tumor and a reduction of its toxicity for the rest of the body. The relative advantage of the IA administration as opposed to the intravenous route is a function of the clearance of the drug and tumor blood From pharmazentrum frankfurt, Klinik und Poliklinik fu ¨r Kiefer und Plastische Gesichtschirurgie, and Institut fu ¨r Neuroradiologie, Klinikum der Johann Wolfgang Goethe-Universita ¨t. Supported in part by the Paul and Willi Weil Stiftung. Received for publication Oct 1, 2002; accepted Jan 2, 2003. Reprint requests: Irmgard Tegeder, MD, pharmazentrum frankfurt, Klinikum der Johann Wolfgang Goethe-Universita ¨t, Theodor Stern Kai 7, 60590, Frankfurt am Main, Germany. E-mail: tegeder@em.uni-frankfurt.de Copyright © 2003 by the American Society for Clinical Pharmacol- ogy & Therapeutics. 0009-9236/2003/$30.00 + 0 doi:10.1016/S0009-9236(03)00008-0 417