Abstract 2663: Hyperthermia improves Cetuximab accumulation in pancreatic cancer mouse model
Authors: Ryoichi Miyamoto, Tatsuya Oda, Shinji Hashimoto, Yoshimasa Akashi, Tomohiro Kurokawa, Yuki Inagaki, Nobuhiro Ohkohchi
Journal: Cancer Research (2014)

Abstract Objective: Histopathological characteristics of pancreatic carcinoma are the presence of abundant stroma that prevent mAb diffusion and consequently hampers mAb from direct attacking cancer cells. With a strong conviction that additional tool that improve mAb penetration and diffusion in dense fibroblastic solid cancer should indispensable for better therapeutic effect, we focused and employed the simple but strongest modalities, heat. Heat might increase tumor blood flow and tumor vessel permeability, leading enhanced accumulation of anticancer mAb. In this study, we aimed the increased accumulation of mAb in mouse pancreatic subcutaneous models and also boosted antitumor effects by applying moderate heat. Methods: Heat generation was completed by hot bathtub method for subcutaneous tumor in nude mice leg. Three human pancreatic cell of different stromal amount were employed (abundant: Capan-1, moderate: BxPC-3, and scant: MIAPaCa-2). At the timing of each tumors growth up to 70mm3, Cetuximab (1 mg/kg) was systematically administrated via caudal vein, subsequently applying heat to tumors for 30 min at three different temperatures of 25°C (control temperature), 37°C (intraabdominal organs), or 41°C (hyperthermia) (n = 5 each). The amount of accumulated Cetuximab were quantified by the fluorescent intensity of Alexa 488 against anti-human IgG at 24 hr, followed by figuring up the intensity of one cancer cell by dividing the total intensity value by the number of a cancer cell nuclei stained with DAPI. Enhanced antitumor effects, among irradiating various heat doses, were evaluated by the tumor volume over time. Results: In Capan-1, the fluorescent intensity per a cancer cell at 25°C, 37°C, 41°C were 675, 1130, 2332 respectively. Similarly, those in BxPC-3 were 673, 1347, 1573, and in MIAPaCa-2 were 1632, 1921, 1949, respectively. In Capan-1 and BxPC-3, the mean tumor growth on day 40 were significantly inhibited at 37°C group (934, 189 mm3), and 41°C group (491, 121 mm3) in compared with 25°C group (1385, 470 mm3) respectively. In MIAPaCa-2, however, that on day 50 was not inhibited at 37 degrees group (109 mm3), and 41 group (151 mm3) as compared with 25 group (123 mm3). Discussion: We demonstrated that hyperthermia actually contributed to measurable add-on antitumor effect for two among three pancreatic cancer models. Intending to provide more add-on effect, we are now evaluating the combined effects of hyperthermia plus applying a cyclic tumor-penetrating peptide (iRGD), which improved anticancer mAb penetration to cancer cells by binding to integrin αv/β3 or β5 and to neuropillin-1 on cancer cells. We suggested that this novel combined strategy would remarkably contribute to the enhanced accumulation of anticancer mAb in tumors and to the enhanced antitumor effects. Citation Format: Ryoichi Miyamoto, Tatsuya Oda, Shinji Hashimoto, Yoshimasa Akashi, Tomohiro Kurokawa, Yuki Inagaki, Nobuhiro Ohkohchi. Hyperthermia improves Cetuximab accumulation in pancreatic cancer mouse model. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2663. doi:10.1158/1538-7445.AM2014-2663