In vivo antitumor effects of chitosan-conjugated docetaxel after oral administration Eunhye Lee a , Hyungjun Kim a , In-Hyun Lee a , Sangyong Jon a,b, ⁎ a Cell Dynamics Research Center, Department of Life Sciences, Gwangju Institute of Science and Technology, Gwangju 500-712, Republic of Korea b AnyGen Corporation, Gwangju TechnoPark, Gwangju 500-712, Republic of Korea abstract article info Article history: Received 16 May 2009 Accepted 16 August 2009 Available online 24 August 2009 Keywords: Docetaxel Chitosan Conjugate Oral delivery Anticancer therapy The purpose of this study is to evaluate in vivo antitumor efficacy and subacute toxicity of docetaxel (DTX) prodrug comprising a conjugate between DTX and low molecular weight chitosan (LMWC) after oral administration. DTX was covalently attached to LMWC via a cleavable linker so as to be released from LMWC-DTX conjugate in body. In vitro cytotoxicity of LMWC-DTX conjugate was evaluated by MTT assay against two human cancer cell lines, showing similar IC 50 values to the parent DTX. The pharmacokinetic data of the conjugate after oral administration revealed that half-life in blood circulation was increased by ~15-fold and AUC (0–∞) was 3.8–6.2 times higher in comparison with the intravenously injected DTX (i.v.). In vivo antitumor efficacy was evaluated in nude mice bearing human non-small cell lung carcinoma (NCI- H358) and glioblastoma (U87MG), respectively. The orally administered LMWC-DTX conjugate (10 mg DTX equivalent/kg) showed comparable antitumor efficacy to the same dose of DTX (i.v.) for both NCI-H358 and U87MG models, but revealed much lower subacute toxicity as seen in body weight loss and hematological toxicity. © 2009 Elsevier B.V. All rights reserved. 1. Introduction Docetaxel (DTX) is a semisynthetic taxoid derived from the European yew tree, Taxus baccata [1] and is an anticancer drug that displays a broad spectrum of antitumor activity [2]. DTX has a similar structure to paclitaxel, but it differs in the 10-position on the baccatin ring and in the 3′-position of the lateral chain. Like other taxanes, DTX is an inhibitor of microtubule depolymerization, but it binds more avidly to the tubulin and hence resides inside cells longer than paclitaxel, which may explain why DTX appears to be 2- to 4-fold more potent than paclitaxel [3–5]. Despite its high potency, DTX exhibits serious dose- limiting toxicities and allergic reactions, which are attributed to formulating vehicles [6,7]. DTX is poorly water soluble and hence is formulated as micellar solutions of Tween 80/ethanol/saline (Tax- otere ® ) [8]. To eliminate toxicities associated with the formulation, alternative dosage forms have been suggested, including polymeric nanoparticles [9–13], emulsions [14–17], and liposomes [18–20]. Another approach reported is based on conjugates between DTX and water soluble carriers or polymers [21–25] to improve solubility and pharmacokinetic profile of DTX. In recent years, there has been an increase in the number of orally active anticancer drugs either in clinic or in development. Contrary to traditional intravenous dosage forms, oral administration of anticancer drugs has many attractive benefits, including cost-effectiveness, facilitat- ing protracted drug administration schedules, accommodating for patient preference, and improving patient compliance [26]. There are many existing factors limiting the successful use of oral anticancer drugs, including problems with drug formulation due to poor aqueous solubility of drugs and more importantly insufficient and fluctuating bioavailability obtained after oral administration [27]. Therefore it is needed to develop a novel approach that can resolve both the solubility and absorption issues. Very recently, we reported on oral chemotherapy of a paclitaxel prodrug in the form of a conjugate with low molecular weight chitosan (LMWC), in which LMWC acted as a carrier [28]. The LMWC-paclitaxel conjugate system exhibited several favorable features for oral delivery, including 1) increased water solubility of paclitaxel by conjugation to water soluble LMWC; 2) prolonged retention of the conjugate in the GI tract due to the mucoadhesive property of LMWC; 3) an ability to bypass the P-glycoprotein mediated efflux; and 4) an ability to bypass cytochrome P450 mediated metabolism, all of which led to dramatically enhanced bioavailability and comparable antitumor efficacy in vivo. Encouraged with the results, we suggested that LMWC-drug conjugate could be used as a technological platform capable of improving oral absorption of drugs. However, since physicochemical properties of LMWC-drug conjugate may be all different with drugs, we are unable to guarantee that the potential platform technology works with the target drug. Here we report a new prodrug of docetaxel in the form of a conjugate between DTX and LMWC, aiming to expand our platform technology to oral delivery of DTX. Synthesis, characterization, drug release profile, in vitro cytotoxicity and mucoadhesive profiles of the LMWC-DTX conjugate were reported. Further, the pharmacokinetics, Journal of Controlled Release 140 (2009) 79–85 ⁎ Corresponding author. Cell Dynamics Research Center, Department of Life Sciences, Gwangju Institute of Science and Technology, 1 Oryong-dong, Gwangju 500-712, Republic of Korea. Tel.: +82 62 970 2504; fax: +82 62 970 2484. E-mail address: syjon@gist.ac.kr (S. Jon). 0168-3659/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.jconrel.2009.08.014 Contents lists available at ScienceDirect Journal of Controlled Release journal homepage: www.elsevier.com/locate/jconrel