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Background: Despite the approval of immune checkpoint inhibitors (ICIs), prognosis of small cell lung cancer (SCLC) remains poor. DLL3 is upregulated in SCLC whereas expression in normal tissues is minimal, representing the favorable profile as a therapeutic target. T cell engager (TCE) is a potent immunotherapy that redirects T cells to tumors expressing a specific antigen. Unlike ICIs, TCEs do not require the recognition of tumor antigens by T cells and thus could be an alternative approach to target tumors where the benefit of ICIs is limited such as SCLC. CD137 (4-1BB) is a costimulatory molecule that promotes T cell activation, proliferation, and survival. Since CD137 agonists synergize with CD3-mediated T cell activation, inducing concurrent CD137 costimulation is a promising strategy to unleash the potential of TCEs. We therefore developed a DLL3/CD3/CD137 trispecific T cell engager composed of two CD3/CD137 dual specific Fabs and one extra DLL3 Fab (DLL3 trispecific, RG6524). Results: We initially investigated the CD3 and CD137 signal transduction in Jurkat cells harboring NFAT or NF-κB reporter cocultured with DLL3 positive cells. DLL3 trispecific showed dose-dependent increase in NFAT and NF-κB activity, indicating that target engagement successfully activated CD3 and CD137 signaling. In the in vitro assay using human PBMC, DLL3 trispecific induced cytotoxicity against SCLC cell lines with EC50s in the two-digit pM range. In vivo efficacy was evaluated in SCLC xenograft models established by engrafting SCLC cell lines into immune humanized NOG mice. DLL3 trispecific showed greater tumor growth inhibition compared to a traditional bispecific T cell engager. Furthermore, flow cytometry-based immunophenotyping revealed that DLL3 trispecific increased T cell number in tumors and improved IFN-γ production from CD8 T cells. We also explored the combination with platinum-based drugs, which are widely used for SCLC, and showed that DLL3 trispecific enhanced the efficacy of platinum-based drugs. These data demonstrated that DLL3 trispecific has the potent in vivo efficacy and the potential for clinical use. We next evaluated whether cytokine release syndrome (CRS) mitigating approaches affect antitumor efficacy. Although prophylactic use of a steroid significantly reduced cytokine production, tumor growth inhibition by DLL3 trispecific remained unchanged. Likewise, tocilizumab treatment did not reduce the efficacy, suggesting that CRS mitigation did not abrogate the therapeutic benefit. We finally assessed the tolerability in non-human primates. DLL3 trispecific did not reach the maximum tolerated dose and was well tolerated up to 16 mg/kg Q2D, the highest dose tested. Conclusion: Our data showed that DLL3 trispecific has potent activity and is well suited for clinical application in SCLC. These findings provide a rationale for the clinical testing of DLL3 trispecific. Citation Format: Hirofumi Mikami, Shu Feng, Sotaro Naoi, Yumiko Azuma, Yoko Kayukawa, Toshiaki Tsunenari, Kentaro Asanuma, Ryutaro Iwabuchi, Hiroaki Nagano, Junko Shinozuka, Masaki Yamazaki, Haruka Kuroi, Siok Wan Gan, Priyanka Chichili, Shun Shimizu, Yutaka Matsuda, Shinya Ishii, Shogo Kamikawaji, Yasuko Kinoshita, Yuichiro Shimizu, Akihisa Sakamoto, Masaru Muraoka, Noriyuki Takahashi, Tatsuya Kawa, Hirotake Shiraiwa, Kenji Kashima, Futa Mimoto, Mika Kamata-Sakurai, Takehisa Kitazawa, Tomoyuki Igawa. A DLL3/CD3/CD137 trispecific T cell engager shows potent antitumor activity in small cell lung cancer models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1872.

Background: Interleukin-6 (IL-6)/signal transducer and activator of transcription 3 (STAT3) pathway inhibition may overcome chemoresistance of metastatic pancreatic cancer (MPC) refractory to gemcitabine + nab-paclitaxel (GN) due to suppression of cancer associated fibroblast (CAF) and increase of drug infiltration in tumor. We sought to determine the safety, recommended dose of tocilizumab (TCZ), an IL-6 receptor monoclonal antibody, and biological correlates of tumor shrinkage in patients with GN-refractory MPC. Methods: This phase 1, dose finding trial was conducted following preclinical study of IL-6 signaling blockade in genetically engineered mouse model of pancreatic cancer (pGEMM) and patients-derived CAF, enrolled 10 patients with MPC that had progressed after GN. During the dose-finding part to determine dose-limiting toxicity (DLT), patients initially received TCZ 8 mg/kg on Day 1 and nab-paclitaxel 100 mg/m2 + gemcitabine 750 mg/m2 on Days 2, 9, and 16. The subsequent dose-expansion part used the TCZ dose identified in the dose-finding study. Before Cycle 1 and at the end of Cycle 1, biopsy of liver metastasis was performed 3 to 5 hours after levofloxacin (LVXF) administration to measure LVFX infiltration in tumor using matrix-assisted laser desorption ionization (MALDI) mass spectrometry imaging (MSI). Results: In pGEMM tumor, mouse IL-6 receptor antibody plus GN led pathological response. The growth of CAFs from patients with pancreatic cancer was inhibited by TCZ. In this phase I study, no DLTs occurred and the recommended dosage of TCZ was determined to be 8 mg/kg. Treatment-emergent adverse events (TEAEs) occurred in 80% of patients (Grade ≥3 in 60%) with decreased neutrophil count (n=5, 7 events) being the most common TEAE. Disease control rate was 80·0% (95%CI: 44·4-97·5) and tumor reduction during cycle 1 was observed in 4 patients who were defined as responder. In paired-biopsied samples, decrease of phosphorylated (p) STAT3 expression in tumor was observed in 7 of 8 patients (88%). Responder-related biological activities were increase of cleaved PARP expression of tumor nuclei (P = 0.01), decrease of proliferative CAF (P = 0.08), and increase of LVFX infiltration in tumor (P = 0.04). Decrease of pSTAT3 expression (P = 0.02) was favor to increase of LVFX infiltration against increase of gamma-H2AX, an index of gemcitabine exposure (P = 0.20). Conclusion: TCZ+GN-rechallenge had a manageable safety profile and showed preliminary activity via inhibition of CAF and gain of intratumoral drug infiltration in MPC. Citation Format: Shuichi Mitsunaga, Masafumi Ikeda, Kazunori Aoki, Kyoko Yamaguchi, Noriaki Sawada, Etsuko Fujii, Masanobu Nishidate, Takashi Fujitomo, Hideaki Mizuno, Yoko Kayukawa, Atsuhiko Kato, Mayu Makikawa, Hiroshi Imaoka, Mitsuhito Sasaki, Kazuo Watanabe, Hiroyuki Tsunoda, Kimio Terao, Atsushi Ochiai. Clinical and translational results of a phase I study, tocilizumab plus gemcitabine/nab-paclitaxel in patient with gemcitabine/nab-paclitaxel-refractory metastatic pancreatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT565.

Background: Blockade of interlukine-6 (IL-6) and programmed death-1-ligand 1 (PD-L1) limits tumour progression in murine models of pancreatic cancer. When PD-L1 expression of metastatic pancreatic cancer (MPC) is increased under the influence of gemcitabine exposure plus IL-6 inhibition, the spectrum of benefit from immune checkpoint blockade may expand to MPC patients with combined blockade of IL-6 and PD-L1 plus gemcitabine-based chemotherapy. We sought to determine PD-L1 expression of liver metastasis during cycle 1 of a phase I study, tocilizumab (TCZ) plus gemcitabine/nab-paclitaxel (GN) in patient with GN-refractory MPC. Methods: This phase 1 study enrolled 10 patients with MPC that had progressed after GN. All patients experienced cycle 1 of TCZ plus GN, TCZ 8 mg/kg on Day 1 and nab-paclitaxel 100 mg/m2 + gemcitabine 750 mg/m2 on Days 2, 9, and 16. Biopsy of liver metastasis was performed before Cycle 1 and at the end of Cycle 1. Tumour microenvironment including PD-L1 expression were evaluated in paired-biopsied specimen from 7 patients by multicolour immunofluorescence staining. Tumour cell and PD-L1 expression were labelled by anti-cytokeratin 19 antibody and anti-PD-L1 antibody clone SP263, respectively. Cell numbers per millimetre squared (cell density) and the percentage of PD-L1 positive cell in tumor area were calculated according to cell types including tumour cell as cytokeratin 19 positive cell and macrophage as CD68 positive cell. Results: Cell density and the percentage of PD-L1 positive tumor cell were 29/mm2 and 1.1% in mean at baseline and tended to be increased up to 142/mm2 (P = 0.11) and 5.2% (P = 0.06) at the end of cycle 1. Means of PD-L1 positive macrophages were 28/mm2 and 6.9% at baseline and were increased to 69/mm2 (P = 0.01) and 14% (P = 0.08). When region of interest was selected from tumor stroma, differences of PD-L1 positive macrophage during cycle 1 was also maintained in cell density (P = 0.02) and the percentage of PD-L1 positive cell (P = 0.06). Conclusion: TCZ+GN induced an increase of PD-L1 expression levels on tumor cell and macrophages. Citation Format: Kyoko Yamaguchi, Etsuko Fujii, Shuichi Mitsunaga, Noriaki Sawada, Masafumi Ikeda, Takashi Fujitomo, Hideaki Mizuno, Yoko Kayukawa, Mayu Makikawa, Kazunori Aoki, Hiroshi Imaoka, Mitsuhito Sasaki, Kazuo Watanabe, Atsukiko Kato, Hiroyuki Tsunoda, Kimio Terao, Atsushi Ochiai. Increased PD-L1 expression levels were observed on both tumor cells and macrophages by tocilizumab plus gemcitabine/nab-paclitaxel treatment in gemcitabine/nab-paclitaxel-refractory metastatic pancreatic cancer patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 6145.

Immune checkpoint inhibitors such as anti-PD1 antibodies have shown promising clinical responses in several solid tumors, however there remain patients who do not show an adequate response. Recent biomarker studies have revealed that the presence of neoantigens in the tumor can determine the level of response, and thus the next challenge will be how to target tumors with a neoantigen level that is too low to be recognized by endogenous cytotoxic T cells. Hope in this area is offered by a T cell-redirecting antibody (TRAB), which bispecifically engages CD3 and a tumor antigen, even at very low expression levels, to activate the inherent cytolytic potential of T cells against target tumor cells. A TRAB is highly potent because T cells are activated only in the presence of the targeted antigens and are not restricted by the specificity of the T cell receptor. Given this very potent cytotoxicity, the key to successfully achieving strong antitumor efficacy while avoiding on-target off-tumor toxicity is to select a highly tumor-selective antigen. Our fully humanized IgG TRAB recognizes CD3 and a highly tumor-selective antigen, glypican-3 (GPC3), which is a fetal protein expressed in a wide variety of tissues during development but suppressed in most adult tissues. On the other hand, an inct101e in GPC3 expression has been reported in hepatocellular carcinoma, gastric cancer, lung squamous cell carcinoma, and other cancers. In nonclinical in vitro pharmacology studies, the anti-GPC3 TRAB elicited activation and proliferation of T cells and T cell-dependent cellular cytotoxicity against a wide variety of GPC3-expressing tumor cells, and showed long-lasting in vivo efficacy against tumor expressing very low levels of GPC3 at a few thousand molecules per cell. Furthermore, in an immunocompetent mouse model using human CD3 transgenic mice, anti-GPC3 TRAB showed strong antitumor efficacy against poorly immunogenic tumors, whereas both the immune checkpoint inhibitors and a conventional ADCC-inducing antibody recognizing GPC3 did not show significant efficacy. Pharmacokinetics and toxicology studies in nonhuman primates showed a plasma half-life comparable to a standard IgG drug, allowing a QW or Q2W regimen in humans, with toxicity which was manageable and reversible; the main observations of transient cytokine elevation and associated clinical symptoms were markedly reduced by steroid premedication. Our anti-GPC3 TRAB, which is supported by proprietary antibody engineering technology (ART-Ig) that enables large-scale GMP manufacturing, has promise as a new approach in cancer immunotherapy. Citation Format: Takahiro Ishiguro, Yasuko Kinoshita, Yuji Sano, Yumiko Azuma, Toshiaki Tsunenari, Natsuki Ono, Yoko Kayukawa, Mika Kamata-Sakurai, Hirotake Shiraiwa, Akihisa Kaneko, Werner Frings, Shunichiro Komatsu, Junichi Nezu, Mika Endo. First-in-class T cell-redirecting bispecific antibody targeting glypican-3: a highly tumor-selective antigen. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr DDT01-05.

Background: T cell-redirecting antibody (TRAB), which bispecifically binds to CD3 and tumor antigen, is a key player in next-generation cancer immunotherapy (CIT). Because TRAB can redirect T cells regardless of their TCR specificity, it is expected to be efficacious in immune checkpoint inhibitor-resistant tumors. The CD19-targeting bispecific T cell engager, blinatumomab, has been used for the treatment of blood cancers, and CEA-TCB and IMCgp100 have shown promising clinical efficacy in solid tumors as well. ERY974 is another promising TRAB targeting glypican-3 (GPC3) and a phase 1 study is in progress (Ishiguro et al., Sci Transl Med 2017). On the other hand, cytokine release syndrome (CRS) has been recognized as a common side effect of TRAB. Thus, mitigation of CRS is an urgent issue. Intra-patient step-up dosing regimens have been incorporated in clinical trials to reduce cytokine release, but the mechanism behind this phenomenon remains elusive. In this study, we pre-clinically explored the phenomenon and its mechanism by using ERY974. Method & Results: GPC3-expressing human cancer cells were incubated with human PBMCs and ERY974. The incubated PBMCs were harvested and mixed with newly prepared GPC3-expressing cancer cells and higher doses of ERY974. The pre-treated PBMCs showed reduced cytokine production compared to that without pre-treatment, while maintaining the same level of T cell-dependent cellular cytotoxicity (TDCC). Comprehensive gene expression analysis of the pre-treated PBMCs was also conducted. A murine cancer cell line expressing human GPC3 was established and implanted into immune competent mice. A mouse surrogate version of ERY974 (mERY974) was first administered at a low dose expected to elicit weak anti-tumor activity, and mice were then treated with a higher dose of mERY974. Anti-tumor activity was similar regardless of the pre-treatment, but plasma cytokine levels were shown to be reduced in the pre-treated mice upon administration of the higher dose of mERY974. Conclusion: Cytokine production following the high-dose ERY974 treatment was mitigated by the low-dose pre-treatment in vitro and in vivo. Cytotoxic activity did not decrease in this setting, thus demonstrating that the pre-treatment selectively suppressed only cytokine production. It is well known that repeated stimulation of TCR leads to T-cell exhaustion. The phenomenon we observed here can also be characterized as a sort of exhaustion, but is quite unconventional. Thus, we propose a new type of exhaustion and suggest calling it ‘Differential exhaustion on cytokine release (DECREASE)’. Management of CRS is critical for the clinical use of TRAB. A detailed analysis of the mechanism of DECREASE currently in progress, is expected to contribute to the development of desired dosing regimens for this new type of CIT agent. Citation Format: Mayumi Hoshino, Yuji Sano, Yasuko Kinoshita, Yumiko Azuma, Toshiaki Tsunenari, Yoko Kayukawa, Mizuho Noguchi, Takahiro Ishiguro, Shohei Kishishita, Noriaki Sawada, Mika Endo, Junichi Nezu. Differential exhaustion on cytokine release (DECREASE) by ERY974, a novel T-cell-redirecting antibody targeting glypican-3: A new type of T-cell exhaustion [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2378.

Introduction: Codrituzumab/GC33/RO5137382 (GC33) is a humanized monoclonal antibody that targets glypican-3 (GPC3), an oncofetal protein expressed on the cell surface of hepatocellular carcinoma (HCC). GC33 interacts with CD16/FcγR3 and triggers antibody-dependent cellular cytotoxicity. Because anti-PD-L1/PD-1 agents have shown marked antitumor effect in various cancer types including HCC, we investigated if GC33 plus anti-PD-L1 mAb combination can augment antitumor efficacy in a mouse hepatoma syngeneic model transfected with human GPC3, named Hepa1-6/hGPC3. Methods: The Hepa1-6/hGPC3 cells were subcutaneously inoculated into C57BL/6J mice. After tumor mass was established, anti-mouse GPC3 mAb (mGC33; once-weekly), anti-mouse PD-L1 mAb (anti-mPD-L1 mAb; once-weekly), or a combination was administered on the first day of treatment (Day 0). Tumor tissues were collected on Day 21 for immunohistochemical (IHC) of F4/80 and PD-L1. To analyze tumor infiltrating lymphocytes (TILs), mGC33, anti-mPD-L1 mAb, or combination was administered to the Hepa1-6/hGPC3 mice. After 3 and 8 days from the 2nd dosing, TILs were analyzed to quantify the CD45-, CD3ε-, CD4-, or CD8α-positive TILs and CD11b+F4/80+ macrophages by flow cytometry. Results: In the Hepa1-6/hGPC3 model, combination therapy demonstrated a marked antitumor effect compared to the corresponding dose of mGC33 or anti-mPD-L1 mAb alone. Pathological complete responses were observed only in combination groups. The necrosis was more marked with combination therapy than with mGC33 or anti-mPD-L1 mAb alone. Though F4/80-positive cells existed mainly in the stroma in the vehicle group, these cells infiltrated the tumor periphery after mGC33 treatment. Most tumor-infiltrating immune cells, including macrophages and multinucleated giant cells, were PD-L1-positive. The combination increased CD45-, CD3ε-, and CD8α-positive T lymphocytes, but not CD4-positive T lymphocytes on Days 3 and 8 after the 2nd dosing. TILs were not increased in mice treated with either mGC33 or anti-mPD-L1 mAb. Conclusions: In this mouse model, mGC33 plus anti-mPD-L1 mAb combination therapy showed more potent antitumor efficacy than either monotherapy. mGC33 treatment enhanced tumor infiltration of PD-L1-positive immune cells, such as macrophages and multinucleated giant cells. Because anti-mPD-L1 mAb can block the binding between PD-L1 on macrophages and PD-1 on T cells, the CD8-positive T lymphocytes may be increased by combination therapy. These results suggest that the combination therapy of GC33 and anti-PD-L1 mAb may be clinically useful as a treatment for HCC. Citation Format: Mika Endo, Yasuko Kinoshita, Kenji Adachi, Yoshinori Narita, Jun Amano, Atsuhiko Kato, Takeshi Watanabe, Yoko Kayukawa, Yoko Miyazaki, Toshihiko Ohtomo. Anti-glypican-3 monoclonal antibody (codrituzumab/GC33/RO5137382) treatment enhances tumor infiltration of PD-L1-positive macrophages, and combination therapy with anti-PD-L1 monoclonal antibody promotes antitumor effects [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2747.

Background: ERY974 is a humanized IgG4 bispecific T cell-redirecting antibody (TRAB) currently in Phase 1 clinical trial (NCT02748837). ERY974 consists of a common light chain and two different heavy chains that respectively recognize glypican-3 (GPC3) and CD3. The Fc portion of ERY974 is modified to lose FcγR binding to prevent GPC3-independent Fc-mediated effector function. However, binding activity to FcRn, an important factor in the PK profile of IgG, is maintained. ERY974 simultaneously binds to GPC3 on the cancer cell surface and to CD3 on the T cell surface, and induces TRAB-dependent cellular cytotoxicity mediated by the potent effector function of T cells. ERY974 shows strong antitumor activity against gastric, lung, ovarian, head & neck, and esophageal cancer-derived xenograft tumors in a non-obese diabetic/severe combined immunodeficiency (NOD-SCID) mouse model injected with human T cells. Cancer immunotherapy, as represented by immune checkpoint inhibitors such as PD-1, PD-L1, and CTLA-4 antibodies, has recently been demonstrating remarkable clinical benefit in various tumor types. However, the number of patients who have survival benefit is limited, and combining cancer immunotherapy with other agents is required to improve the efficacy. Although ERY974 monotherapy is expected to show clinical activity based on the preclinical data, we examined whether further improvement of ERY974-induced efficacy is attained by combination with chemotherapy. Method & Results: We evaluated the combination effect of ERY974 with chemotherapy against xenograft tumors of MKN45 (gastric cancer) or NCI-H446 (lung cancer) either in a NOD-SCID mouse model injected with human T cells or in a humanized non-obese diabetic/shi-scid/IL-2Rγnull model in which differentiated human T cells are constitutively supplied. Although ERY974 monotherapy shows only minor antitumor effect against MKN45 and NCI-H446, combination therapy remarkably enhanced efficacy. In particular, ERY974 in combination with paclitaxel or cisplatin in NCI-H446 tumors caused a tumor disappearance without regrowth for a long period. Conclusion: These preclinical data suggest the possibility that the strategy of combining ERY974 with chemotherapy may succeed in increasing the clinical benefit. Now the combination effect is being further investigated to clarify the mechanism. Citation Format: Yuji Sano, Yumiko Azuma, Toshiaki Tsunenari, Yasuko Kinoshita, Yoko Kayukawa, Hironori Mutoh, Yoko Miyazaki, Takahiro Ishiguro, Shohei Kishishita, Yoshiki Kawabe, Mika Endo. Combining ERY974, a novel T cell-redirecting bispecific antibody targeting glypican-3, with chemotherapy profoundly improved antitumor efficacy over its monotherapy in xenograft model [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3653. doi:10.1158/1538-7445.AM2017-3653

We present efficacy data for the T cell-redirecting antibody (TRAB) with highly potent anti-tumor efficacy. Anti-Glypican-3 (GPC3) TRAB is a humanized IgG4 bispecific antibody that simultaneously binds to GPC3 on the cancer cell surface and to CD3 on the T cell surface. Anti-GPC3 TRAB utilizes T cells as effectors to induce strong TRAB dependent cellular cytotoxicity (TDCC) in the presence of GPC3-expressing cells. Treatment with anti-GPC3 TRAB first activates T cells by increasing the expression of CD25 and CD69 and also upregulating cytokines IL-2, IL-4, IL-6, IL 10, IFNγ, and TNF, and then it enhances the proliferation of T cells. Anti-GPC3 TRAB showed antitumor activity against xenograft tumors derived from various cancer types — MKN-74 (human gastric adenocarcinoma), PC-10 (human lung squamous cell carcinoma), TOV-21G (human ovarian clear cell carcinoma), and KYSE70 (human esophageal squamous cell carcinoma) — in a NOD-SCID mouse model injected with human T cells. Although recent immunotherapy, as represented by immune check point inhibitors PD-1, PD-L1, and CTLA-4 antibodies, showed promising efficacy in human, not every patient can benefit from this immunotherapy, because the significant efficacy shown in patients by a blockade of immune checkpoints is closely related to the tumor microenvironment. The immune check point inhibitors show high efficacy against inflamed tumors, because these have been sufficiently infiltrated by cytotoxic T cells that recognize cancer-specific antigens. However, they do not have efficacy against non inflamed tumors. In an immunocompetent mouse model using human CD3 transgenic mice, neither the inhibitors that block immune checkpoints (such as PD-1, PD-L1 and CTLA-4) nor a conventional ADCC antibody recognizing GPC3 could show significant efficacy against a poorly immunogenic LLC1/hGPC3 tumor. However, anti-GPC3 TRAB showed efficacy against this poorly immunogenic tumor by utilizing any kind of T cell as effectors irrespective of TCR specificity, including not only CD8-positive but also CD4-positive T cells. The studies we present show that anti-GPC3 TRAB is a promising drug with high efficacy utilizing all kinds of T cells as effectors. The compound is expected to have efficacy even in patients with poorly immunogenic tumors, in which an immune checkpoint blockade fails to show efficacy. Citation Format: Yasuko Kinoshita, Takahiro Ishiguro, Yuji Sano, Yumiko Azuma, Toshiaki Tsunenari, Natsuki Ono, Yoko Kayukawa, Otoya Ueda, Naoko A. Wada, Hiroshi Hino, Koichi Jishage, Hirotake Shiraiwa, Mika Kamata-Sakurai, Junichi Nezu, Mika Endo. Anti-GPC3 TRAB, a first-in-class T cell-redirecting bispecific antibody targeting glypican-3 with potent in vitro and in vivo antitumor efficacy against solid tumors. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1482.

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

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.