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Updated: Dec 27, 2025
Experimental Melanoma Immunotherapy Model Using Tumor Vaccination with a Hematopoietic Cytokine
Published on: February 24, 2023
Melanoma-Secreted Lysosomes Trigger Monocyte-Derived Dendritic Cell Apoptosis and Limit Cancer Immunotherapy
Nadine Santana-Magal1, Leen Farhat-Younis1, Amit Gutwillig1
1Department of Pathology, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel.
Abstract:
The recent success of checkpoint blockade therapies has established immunotherapy as one of the most promising treatments for melanoma. Nonetheless, a complete curative response following immunotherapy is observed only in a fraction of patients. To identify what factors limit the efficacy of immunotherapies, we established mouse models that cease to respond to immunotherapies once their tumors exceed a certain stage. Analysis of the immune systems of the organisms revealed that the numbers of tumor-infiltrating dendritic cells (TIDC) drastically decreased with time. Further, in contrast to the current paradigm, once melanoma was established, TIDC did not migrate into sentinel lymph nodes. Instead, they underwent local cell death due to excessive phagocytosis of lysosomes. Importantly, TIDC were required to license the cytotoxic activity of tumor CD8+ T cells, and in their absence, T cells did not lyse melanoma cells. Our results offer a paradigm shift regarding the role of TIDC and a framework to increase the efficacy of immunotherapies. SIGNIFICANCE: This work redefines the role of monocyte-derived dendritic cells in melanoma and provides a novel strategy to increase the efficacy of T-cell-based immunotherapies in nonresponding individuals. GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/80/10/1942/F1.large.jpg.
Insights
Tumor-infiltrating dendritic cells (TIDC) are crucial for immunotherapy efficacy in melanoma. In advanced melanoma, TIDC undergo cell death, hindering CD8+ T cell activation and limiting treatment response.
Area of Science:
- Immunology
- Oncology
- Cancer Research
Background:
- Immunotherapy, particularly checkpoint blockade, shows promise for melanoma treatment.
- However, a significant portion of patients do not achieve a complete response.
- Understanding factors limiting immunotherapy efficacy is crucial for improving patient outcomes.
Purpose of the Study:
- To investigate the factors limiting immunotherapy efficacy in advanced melanoma.
- To elucidate the role of tumor-infiltrating dendritic cells (TIDC) in melanoma progression and treatment response.
Main Methods:
- Establishment of mouse models with immunotherapy-resistant melanoma.
- Analysis of immune cell populations, specifically TIDC, in tumor microenvironments.
- Investigation of TIDC migration, survival, and function in relation to tumor stage.
Main Results:
- TIDC numbers significantly decreased in advanced melanoma models.
- TIDC failed to migrate to sentinel lymph nodes and underwent local cell death via excessive lysosomal phagocytosis.
- TIDC were essential for licensing cytotoxic activity of CD8+ T cells, which was impaired in their absence.
Conclusions:
- This study redefines the role of TIDC in melanoma, highlighting their critical function in enabling T-cell-mediated tumor lysis.
- The findings suggest a novel strategy to enhance immunotherapy efficacy by targeting TIDC survival and function in nonresponding patients.
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