Search

Epithelioid sarcoma (ES) is a rare soft tissue neoplasm with high recurrence rates. Wide surgical resection remains the only potential curative treatment. ES presents most commonly on the fingers, hands and forearm, making light-based cancer cell-targeted therapies such as near-infrared photoimmunotherapy (NIR-PIT) that is target-specific, but with limited penetration depth, suitable for ES treatment. We established that CD44 and EGFR were overexpressed in ES patient samples and in the VA-ES-BJ human ES cell line. NIR-PIT of VA-ES-BJ cells using antibody photosensitizer conjugates, prepared by conjugating a CD44 or EGFR monoclonal antibody to the photosensitizer IR700, confirmed that NIR-PIT with both conjugates resulted in cell death. Neither treatment with NIR light alone nor treatment with the conjugates but without NIR light were effective. CD44-IR700-PIT resulted in greater cell death than EGFR-IR700-PIT, consistent with the increased expression of CD44 by VA-ES-BJ cells. In tumors, EGFR-IR700 exhibited a higher tumor-to-normal ratio, as determined by in vivo fluorescence imaging, and a higher anti-tumor growth effect, compared to CD44-IR700. No antitumor effect of the EGFR antibody or the photosensitizer conjugate alone was observed in vivo. Our data support evaluating the use of EGFR-IR700-PIT in the management of ES for detecting and eliminating ES cells in surgical margins, and in the treatment of superficial recurrent tumors.

Abstract Introduction Therapy‐induced senescent cancer and stromal cells secrete cytokines and growth factors to promote tumor progression. Therefore, senescent cells may be novel targets for tumor treatment. Near‐infrared photoimmunotherapy (NIR‐PIT) is a highly tumor‐selective therapy that employs conjugates of a molecular‐targeting antibody and photoabsorber. Thus, NIR‐PIT has the potential to be applied as a novel senolytic therapy. This study aims to investigate the efficacy of NIR‐PIT treatment on senescent cancer and stromal cells. Methods Two cancer cell lines (human lung adenocarcinoma A549 cells and human pancreatic cancer MIA PaCa‐2 cells) and two normal cell lines (mouse fibroblast transfected with human epidermal growth factor receptor 2 [HER2] cells and human fibroblast WI38 cells) were used. The cytotoxicity of NIR‐PIT was evaluated using anti‐epidermal growth factor receptor (EGFR) antibody panitumumab and anti‐HER2 antibody transtuzumab. Results Cellular senescence was induced in A549 and MIA PaCa‐2 cells by 10 Gy γ‐irradiation. The up‐regulation of cellular senescence markers and characteristic morphological changes in senescent cells, including enlargement, flattening, and multinucleation, were observed in cancer cells after 5 days of γ‐irradiation. Then, NIR‐PIT targeting EGFR was performed on these senescent cancer cells. The NIR‐PIT induced morphological changes, including bleb formation, swelling, and the inflow of extracellular fluid, and induced a significant decrease in cellular viability. These results suggested that NIR‐PIT may induce cytotoxicity using the same mechanism in senescent cancer cells. In addition, similar morphological changes were also induced in radiation‐induced senescent 3T3‐HER2 fibroblasts by NIR‐PIT targeting human epidermal growth factor receptor 2. Conclusion NIR‐PIT eliminates both senescent cancer and stromal cells in vitro suggesting it may be a novel strategy for tumor treatment.

Summary: Background: Noninvasive in vivo cell tracking is valuable in understanding the mechanisms that enhance anti-cancer immunity. We have recently developed a new method called phototruncation-assisted cell tracking (PACT), that uses photoconvertible cell tracking technology to detect in vivo cell migration. This method has the advantages of not requiring genetic engineering of cells and employing tissue-penetrant near-infrared light. Methods: We applied PACT to monitor the migration of immune cells between a tumour and its tumour-draining lymph node (TDLN) after near-infrared photoimmunotherapy (NIR-PIT). Findings: PACT showed a significant increase in the migration of dendritic cells (DCs) and macrophages from the tumour to the TDLN immediately after NIR-PIT. This migration by NIR-PIT was abrogated by inhibiting the sphingosine-1-phosphate pathway or Gαi signaling. These results were corroborated by intranodal immune cell profiles at two days post-treatment; NIR-PIT significantly induced DC maturation and increased and activated the CD8+ T cell population in the TDLN. Furthermore, PACT revealed that NIR-PIT significantly enhanced the migration of CD8+ T cells from the TDLN to the tumour four days post-treatment, which was consistent with the immunohistochemical assessment of tumour-infiltrating lymphocytes and tumour regression. Interpretation: Immune cells dramatically migrated between the tumour and TDLN following NIR-PIT, indicating its potential as an immune-stimulating therapy. Also, PACT is potentially applicable to a wide range of immunological research. Funding: This work was supported by the Intramural Research Program of the National Institutes of Health, National Cancer Institute, Centre for Cancer Research (grant number: ZIA BC011513 and ZIA BC011506).

Near-infrared photoimmunotherapy (NIR-PIT) is a new cancer therapy that uses NIR light and conjugates of a tumor-targeting monoclonal antibody and phthalocyanine dye. In clinical practice, frontal and cylindrical diffusers are the only options for NIR illumination. However, illumination in a narrow space is technically difficult with such diffusers. Therefore, we evaluated a lateral illumination system using a lateral emitting laser (LEL) fiber. The LEL fiber illuminated a certain area in a lateral direction. NIR-PIT with an LEL fiber reduced luciferase activity in a light-dose-dependent manner in A431-GFP-luc cells in vitro and significantly suppressed tumor proliferation in a xenograft mouse model. To evaluate the usefulness of the LEL fiber in the illumination of a narrow space, a tumor was illuminated from the inside of a cylinder, mimicking a narrow space, and the fluorescence intensity in the tumor was monitored. In the frontal diffuser, NIR light was unevenly delivered and little light reached a distal tumor area from the illuminated side. By contrast, the LEL fiber allowed a uniform illumination of the entire tumor, and a loss of fluorescence was observed even in distal areas. These findings suggested that the LEL fiber can be used for NIR-PIT and is suitable for NIR light illumination in a narrow space.