Hyperthermia-enhanced tumor accumulation and antitumor efficacy of a doxorubicin-conjugate with a novel macromolecular carrier system in mice with non-small cell lung cancer

A novel drug delivery system (DDS) compound was formed by binding doxorubicin hydrochloride (DXR) to the macromolecular carrier carboxymethyldextran polyalcohol (CM-Dex-PA) via the peptidyl spacer (GGFG: Gly-Gly-Phe-Gly). Its use in a murine tumor model confirmed that the DDS (CM-Dex-PA-GGFG-DXR) was retained in the blood and distributed in tumor tissue. The combined use of hyperthermia (HT: 41-42 degrees C for 40 min) and DXR-conjugate (5, 10 or 20 mg/kg i.v.) on tumor accumulation and efficacy was investigated in a murine model of non-small cell lung cancer. Tumor size was measured and the tumor inhibition rate (IR) was calculated. The mean tumor concentration of conjugated DXR in the DXR-conjugate group was 9.40 microg/g compared with 19.04 microg/g in the DXR-conjugate + HT group (p=0.0008). The antitumor efficacy of the DXR-conjugate was significantly enhanced in the groups receiving the combination therapy (p=0.0039, p=0.0250). Significant differences were found between the groups given DXR and those given DXR-conjugate (p=0.0492, p=0.0104). The results demonstrate that the antitumor efficacy of DXR-conjugate is significantly superior to that of DXR alone and the combined use of DXR-conjugate and HT increases the drug's concentration in the tumor, with significant enhancement of antitumor efficacy.