Abstract B095: Novel anti-CD147 antibodies inducing activation of SMAD signaling and tumor shrinkage in intractable cancer models

Abstract CD147, a type I membrane protein, is highly expressed in various cancers and is involved in the growth, metastasis, and activation of inflammatory signals in cancer cells via interaction with various molecules, such as integrins, CD44, and monocarboxylate transporters. Additionally, the expression of CD147 in tumors positively correlates with poor prognosis in various cancers. Therefore, CD147 is an attractive target for cancer therapy. However, there have been no successful drugs targeting CD147 so far, possibly because it is a multifunctional protein interacting with multiple molecules, making it challenging to discover a relevant CD147-targeting drug candidate by general in vitro screening methodologies. In this study, we developed novel anti-CD147 antibodies, which showed significant antitumor efficacy in immune-deficient mice bearing human pancreatic cancer cell lines, PANC-1 or MIA PaCa-2. Six anti-CD147 antibodies showing in vivo anti-tumor efficacy were obtained; one mouse IgG3, two rat IgG2b, two rat IgG1, and one rat IgG2a antibodies. Analysis of antibody dependent cellular toxicity, antibody-dependent cellular phagocytosis, and complement-dependent cytotoxicity of chimeric and humanized antibodies with human IgG2 or IgG4P derived from the obtained 6 anti-CD147 antibodies, #147A/B/C/D/E/F, suggested no significant immune-effector function for these antibodies. Despite lacking effector function, these antibodies exhibited significant in vivo antitumor activity, suggesting that the mechanism underlying their anti-tumor efficacy did not involve their effector function. We also found that the anti-tumor efficacy of antibodies #147A and #147B positively correlated with SMAD4 protein expression rather than CD147 protein expression in 10 pancreatic cancer xenograft models (correlation coefficient of #147B: anti-tumor efficacy vs. CD147, 0.245; vs. SMAD4, 0.9328). Moreover, the administration of anti-CD147 antibodies upregulated rhoB expression in an anti-CD147 antibody-sensitive SMAD4-positive MIA PaCa-2 graft mouse model. The stable expression of SMAD4 increased the sensitivity to the anti-CD147 antibody, ch4#147A (chimeric IgG4P derived from #147A) in xenograft mice inoculated with the BxPC-3 pancreatic cancer cell line, which is originally negative for SMAD4 and has low sensitivity to anti-CD147 antibodies. These data suggest that the expression of SMAD4 and activation of SMAD signaling are functionally important for susceptibility to anti-CD147 antibody treatment. The humanized anti-CD147 IgG4P antibody, h4#147D, derived from #147D with cross reactivity to monkey CD147, showed superior anti-tumor efficacy with complete tumor reduction, compared to standard anticancer drugs, including gemcitabine, imatinib, and sorafenib, in xenograft mice bearing corresponding cancer cell lines, MIA PaCa-2, KU812 chronic myeloid leukemia, and HepG2 liver cancer cell lines, respectively. No toxicity of h4#147D was observed in cynomolgus monkeys at a single dose of 100 mg/kg. These data suggest that h4#147D might be a novel anti-CD147 antibody, which could induce SMAD activation and tumor shrinkage in multiple xenograft models. Therefore, it has potential as a promising antitumor therapeutic antibody with superior anti-tumor efficacy to existing therapy. Citation Format: Keisuke Fukuchi, Kayoko Nanai, Shoji Yamamoto, Jun Tsukada, Yusuke Totoki, Koichiro Inaki, Masato Ishigami, Naoyuki Makita, Yoko Nakano, Chigusa Yoshimura, Kozo Yoneda, Masato Amano, Kensuke Nakamura, Yoshiyuki Kanari, Yoko Oda, Haruyuki Nishigohri, Rika Nakano, Atsuko Nishida, Kenji Murakami, Yumi Matsui, Naomi Kasanuki, Shoji Midori, Satoko Funo, Sayako Takahashi, Hironobu Komori, Toshiaki Ohtsuka, Toshinori Agatsuma. Novel anti-CD147 antibodies inducing activation of SMAD signaling and tumor shrinkage in intractable cancer models [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; 2019 Oct 26-30; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2019;18(12 Suppl):Abstract nr B095. doi:10.1158/1535-7163.TARG-19-B095