Near-Infrared Photoimmunotherapy Targeting GPR87: Development of a Humanized Anti-GPR87 Mab and Therapeutic Efficacy on a Lung Cancer Mouse Model

Abstract

Background: GPR87 is a G protein receptor that is specifically expressed in tumor cells, such as lung cancer, and rarely expressed in normal cells. GPR87 is a promising target for cancer therapy, but its ligand is controversial. Near-infrared photoimmunotherapy (NIR-PIT) is a novel cancer therapy in which a photosensitizer, IRDye700DX (IR700), binds to antibodies and specifically destroys target cells by irradiating them with near-infrared light. Here, we aimed to develop a NIR-PIT targeting GPR87. Methods: We evaluated the expression of GPR87 in resected specimens of lung cancer and malignant pleural mesothelioma (MPM) resected at Nagoya University Hospital using immunostaining. Humanized anti GPR87 antibody (huGPR87) was generated by introducing VH and VL genes into mouse anti GPR87 antibody which generated by standard hybridoma method. HuGPR87 was conjugated with IR700 and the therapeutic effect of NIR-PIT was evaluated in vitro and in vivo using lung cancer or MPM cell lines. Findings: Among the surgical specimens, 54% of lung cancer and 100% of MPM showed high expression of GPR87. It showed therapeutic effects on lung cancer and MPM cell lines in vitro, and showed therapeutic effects in multiple models in vivo. Interpretation: These results suggest that NIR-PIT targeting GPR87 is a promising therapeutic approach for the treatment of thoracic cancer. Funding: Funding: This research was supported by the Program for Developing Next-generation Researchers (Japan Science and Technology Agency), KAKEN (18K15923, JSPS), Souhatsu (JST). Declaration of Interest: None to declare Ethical Approval: All in vivo procedures were performed in accordance with the Nagoya University Animal Care and Use Committee's Guide for the Management and Use of Laboratory Animal Resources (approval numbers 2017-29438, #2018-30096, # 2019-31234, #2020-20104). The use of specimens from patients was approved by the Ethics Committee of the Nagoya University Clinical Research Committee (Approval No. 2018-0046).