Katsushi Kouda

Combined treatment of pancreatic cancer xenograft with 90Y-ITGA6B4-mediated radioimmunotherapy and PI3K/mTOR inhibitor

AIM To investigate the therapeutic effect of combined integrin α6β4-targeted radioimmunotherapy (RIT) and PI3K/mTOR inhibitor BEZ235 in a pancreatic cancer model. METHODS Phosphorylation of Akt, mTOR, the downstream effectors eukaryotic initiation factor 4E binding protein 1 (4EBP1) and S6 ribosomal protein (S6) were evaluated in BxPC-3 human pancreatic cancer cells treated with Yttrium-90 (90Y) labeled anti-integrin α6β4 antibody (ITGA6B4) and BEZ235 by western blotting. The cytotoxic effect of BEZ235 was investigated using a colony formation assay. Therapeutic efficacy enhancement by oral BEZ235 administration was assessed using mice bearing BxPC-3 xenograft tumors. Tumor volume measurements and immunohistochemical analyses (cell proliferation marker Ki-67, DNA damage marker p-H2AX and p-4EBP1 staining) of tumors were performed for evaluation of combined treatment with 90Y-ITGA6B4 plus BEZ235, or each arm alone. RESULTS We found that phosphorylation of Akt (p-Akt), 4EBP1 (p-4EBP1) and S6 (p-S6) was inhibited by BEZ235. Colony formation in BxPC-3 cells was additively suppressed by the combination of 90Y-ITGA6B4 and BEZ235. Pretreatment with BEZ235 before 90Y-ITGA6B4 exposure resulted in significant reduction of cells plating efficiency (PE) (0.54 ± 0.11 vs 2.81 ± 0.14 with 185 kBq/mL 90Y-ITGA6B4 exposure, P < 0.01; 0.39 ± 0.08 vs 1.88 ± 0.09 with 370 kBq/mL 90Y-ITGA6B4 exposure, P < 0.01) when 5 × 103 cells per dish were plated. In vivo, the combined treatment with 90Y-ITGA6B4 plus BEZ235 enhanced the inhibition of tumor growth and statistically significant differences of relative tumor volume were observed for 27 d after the treatment start date when compared with the 90Y-ITGA6B4 single injection treatment (1.03 ± 0.38 vs 1.5 ± 0.15 at Day 27, P < 0.05), and for 41 d when compared with the BEZ235 treatment alone (1.8 ± 0.7 vs 3.14 ± 1.19 at Day 41, P < 0.05). Tumors from treatment groups showed reduction in volumes, decreased Ki-67-positive cells, increased p-H2AX-positive cells and decreased p-4EBP1 expression. CONCLUSION The therapeutic efficacy of 90Y-ITGA6B4-RIT can be improved by combining with dual PI3K and mTOR inhibitor, BEZ235, in a pancreatic cancer model suggesting potential clinical application.

Abstract 4323: Antibodies against TfR inhibit growth of tumor cells both in vitro and in vivo.

Transferrin receptor (TfR) is a type II transmembrane glycoprotein regulating intracellular uptake of iron, and is therefore involved in cell survival and proliferation. TfR has been reported to be more abundantly expressed in dividing cells, e.g. malignant cells, than in quiescent cells, as in most normal cells. Therefore, it is regarded as a potential target for usage in cancer therapy. In the present study, we generated a panel of human anti-TfR antibodies and evaluated its anti-tumor effect both in vitro and in vivo. We found that several antibodies inhibited cell proliferation in various tumor cells, and elicited antibody dependent cellular cytotoxicity (ADCC) activity. Among these antibodies, PPMXT001 and PPMXT002 exerted a significant anti-tumor activity in several xenograft models. PPMXT001 completely suppressed tumor growth in a pancreatic cancer model (MIAPaCa2). PPMXT002 also inhibited tumor growth by 60∼80% in several solid cancer xenograft models including bladder cancer, colon cancer, prostate cancer, and pancreatic cancer. These findings showed that PPMXT001 and PPMXT002 could be potent candidates for developing antibody therapeutics to treat cancer. Citation Format: Lilin Zhang, Yoshinori Ukai, Fumiko Nomura, Youichi Aikawa, Yoko Kayukawa, Katsuyuki Mitomo, Katsushi Kouda, Romi Kodaka, Gene Kurosawa, Yoshikazu Kurosawa, Kazuhiro Morishita, Yukio Sudo. Antibodies against TfR inhibit growth of tumor cells both in vitro and in vivo . [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4323. doi:10.1158/1538-7445.AM2013-4323

Abstract 2428: PPMX-2017: Antibody against CDH3 with potent efficacy against lung cancer

Proceedings: AACR 101st Annual Meeting 2010‐‐ Apr 17‐21, 2010; Washington, DC Cadherin 3/P-cadherin (CDH3) is a member of cadherin family proteins involved in the cell-cell adhesion. Based on a genome-wide cDNA microarray analysis of pancreatic cancer, we found that CDH3 is overexpressed in pancreatic cancer. We also confirmed by our immunohistochemistry study that CDH3 protein was expressed highly in pancreatic, lung, colon and other types of cancer tissues but not in normal tissues. Since CDH3 is a transmembrane glycoprotein and overexpressed in cancer tissues, it is an attractive therapeutic target for various kinds of cancer. In this present study, we generated a series of monoclonal antibodies against CDH3 and evaluated their anti-tumor effect both in vitro and in vivo. PPMX2017, an antibody from the series, is an anti-human CDH3 specific mouse IgG2a antibody. The in vitro studies demonstrated that PPMX2017 elicited strong antibody dependent cellular cytotoxicity (ADCC) activity on CDH3-positive cancer cell lines (lung cancer: NCI-H358 and A431, pancreatic cancer: KLM1 and Bxpc3.). Furthermore, PPMX2017 showed a significant antitumor effect in a therapeutic xenograft model of lung cancer where NCI-H358 cell-generated tumors grew to 70∼90 mm3 before administration of this antibody. PPMX2017 suppressed tumor growth by 60∼80% compared with control IgG in a dose range of 0.3mg∼5mg/kg. These findings show that CDH3 is a potential target for cancer therapy and PPMX2017 is a candidate for the development of antibody therapeutics. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2428.