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Abstract Pulmonary fibrosis is a progressive disease caused by interstitial inflammation. Treatments are extremely scarce; therapeutic drugs and transplantation therapies are not widely available due to cost and a lack of donors, respectively. Recently, there has been a high interest in regenerative medicine and exponential advancements in stem cell-based therapies have occurred. However, a sensitive imaging technique for investigating the in vivo dynamics of transplanted stem cells has not yet been established and the mechanisms of stem cell-based therapy remain largely unexplored. In this study, we administered mouse adipose tissue-derived mesenchymal stem cells (mASCs) labeled with quantum dots (QDs; 8.0 nM) to a mouse model of bleomycin-induced pulmonary fibrosis in an effort to clarify the relationship between in vivo dynamics and therapeutic efficacy. These QD-labeled mASCs were injected into the trachea of C57BL/6 mice seven days after bleomycin administration to induce fibrosis in the lungs. The therapeutic effects and efficacy were evaluated via in vivo/ex vivo imaging, CT imaging, and H&E staining of lung sections. The QD-labeled mASCs remained in the lungs longer and suppressed fibrosis. The 3D imaging results showed that the transplanted cells accumulated in the peripheral and fibrotic regions of the lungs. These results indicate that mASCs may prevent fibrosis. Thus, QD labeling could be a suitable and sensitive imaging technique for evaluating in vivo kinetics in correlation with the efficacy of cell therapy.

Abstract Background Human epidermal growth factor receptor 2 (HER2) is tyrosine kinase receptor that belongs to the ErbB family and is overexpressed on the membrane surface of various cancer cells, including small cell lung cancer (SCLC); however, no HER2 targeted therapy for SCLC have yet been established. Near‐infrared photoimmunotherapy (NIR‐PIT) is a novel cancer therapy based on photo‐absorber, IRDye‐700DX (IR700), ‐antibody conjugates, and near‐infrared (NIR) light. Methods We used HER2‐positive SCLC parental cell lines (SBC‐3) and its chemoresistant cell lines, and examined therapeutic efficacy of HER2 targeting NIR‐PIT using anti HER2 antibody trastuzumab. Results We found that HER2 expression was upregulated on chemoresistant cell lines, especially cisplatin‐resistance (SBC‐3/CDDP). In vitro, the rate of cell death increased with the amount of NIR‐light irradiation, and it was significantly higher in SBC‐3/CDDP than in SBC‐3. In vivo, tumor growth was more suppressed in SBC‐3/CDDP group than in SBC‐3 group, and survival period tended to be prolonged. Conclusion In this study, we demonstrated that HER2 targeting NIR‐PIT using trastuzumab is promising therapy for HER2‐positive SCLC, and is more effective when HER2 expression is upregulated due to CDDP resistance, suggesting that the HER2 expression level positively corelated with the efficacy of NIR‐PIT.

Abstract Ideal cancer treatments specifically target and eradicate tumor cells without affecting healthy cells. Therefore, antibody‐based therapies that specifically target cancer antigens can be considered ideal cancer therapies. Antibodies linked with small‐molecule drugs (i.e., antibody–drug conjugates [ADCs]) are widely used in clinics as antibody‐based therapeutics. However, because tumors express antigens heterogeneously, greater target specificity and stable binding of noncleavable linkers in ADCs limit their antitumor effects. To overcome this problem, strategies, including decreasing the binding strength, conjugating more drugs, and targeting tumor stroma, have been applied, albeit with limited success. Thus, further technological advancements are required to remotely control the ADCs. Here, we described a drug that is photo‐releasable from an ADC created via simple double conjugation and its antitumor effects both on target and nontarget tumor cells. Specifically, noncleavable T‐DM1 was conjugated with IR700DX to produce T‐DM1‐IR700. Although T‐DM1‐IR700 itself is noncleavable, with NIR‐light irradiation, it can release DM1‐derivatives which elicited antitumor effect in vitro mixed culture and in vivo mixed tumor model which are mimicking heterogeneous tumor‐antigen expression same as real clinical tumors. This cytotoxic photo‐bystander effect occurred in various types mixed cultures in vitro, and changing antibodies also exerted photo‐bystander effects, suggesting that this technology can be used for targeting various specific cancer antigens. These findings can potentially aid the development of strategies to address challenges associated with tumor expression of heterogeneous antigen.

Background: GPR87 is a G-protein receptor that is specifically expressed in tumour 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 photosensitiser, 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. Humanised anti-GPR87 antibody (huGPR87) was generated by introducing CDRs from mouse anti-GPR87 antibody 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: This research was supported by the Program for Developing Next-generation Researchers (Japan Science and Technology Agency), KAKEN (18K15923, 21K07217, JSPS), FOREST-Souhatsu, CREST (JST).

Background: Small cell lung cancer (SCLC) has a poor prognosis, and its treatment options are limited. Delta-like protein 3 (DLL3) is expressed specifically in SCLC and is considered a promising therapeutic target for patients with this disease. Rovalpituzumab tesirine (Rova-T) was the first antibody-drug conjugate targeting DLL3. Although Rova-T development was unfortunately terminated, DLL3 remains an ideal target for SCLC. Near infrared photoimmunotherapy (NIR-PIT) is a new form of cancer treatment that employs an antibody-photosensitiser conjugate followed by NIR light exposure and damage target cells specifically. In this study, we demonstrate DLL3-targeted NIR-PIT to develop a novel molecularly targeted treatment for SCLC. Methods: The anti-DLL3 monoclonal antibody rovalpituzumab was conjugated to an IR700 photosensitiser (termed ‘rova-IR700’). SCLC cells overexpressing DLL3 as well as non-DLL3-expressing controls were incubated with rova-IR700 and then exposed to NIR-light. Next, mice with SCLC xenografts were injected with rova-IR700 and irradiated with NIR-light. Findings: DLL3-overexpressing cells underwent immediate destruction upon NIR-light exposure, whereas the control cells remained intact. The xenograft in mice treated with rova-IR700 and NIR-light shrank markedly, whereas neither rova-IR700 injection nor NIR-light irradiation alone affected tumour size. Interpretation: Our data suggest that targeting of DLL3 using NIR-PIT could be a novel and promising treatment for SCLC. Funding: Research supported by grants from the Program for Developing Next-generation Researchers (Japan Science and Technology Agency), KAKEN (18K15923, JSPS), Medical Research Encouragement Prize of The Japan Medical Association, The Nitto Foundation, Kanae Foundation for the Promotion of Medical Science. Keywords: Photoimmunotherapy, DLL3, Small cell lung cancer, Bioluminescence, In vivo imaging

Malignant pleural mesothelioma (MPM) has extremely limited treatment despite a poor prognosis. Moreover, molecular targeted therapy for MPM has not yet been implemented; thus, a new targeted therapy is highly desirable. Near-infrared photoimmunotherapy (NIR-PIT) is a recently developed cancer therapy that combines the specificity of antibodies for targeting tumors with toxicity induced by the photoabsorber after exposure to NIR-light. In this study, we developed a new phototherapy targeting podoplanin (PDPN) for MPM with the use of both NIR-PIT and an anti-PDPN antibody, NZ-1. An antibody–photosensitizer conjugate consisting of NZ-1 and phthalocyanine dye was synthesized. In vitro NIR-PIT-induced cytotoxicity was measured with both dead cell staining and luciferase activity on various MPM cell lines. In vivo NIR-PIT was examined in both the flank tumor and orthotopic mouse model with in vivo real-time imaging. In vitro NIR-PIT-induced cytotoxicity was NIR-light dose dependent. In vivo NIR-PIT led to significant reduction in both tumor volume and luciferase activity in a flank model (p < 0.05, NIR-PIT group versus NZ-1-IR700 group). The PDPN-targeted NIR-PIT resulted in a significant antitumor effect in an MPM orthotopic mouse model (p < 0.05, NIR-PIT group versus NZ-1-IR700 group). This study suggests that PDPN-targeted NIR-PIT could be a new promising treatment for MPM.