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Updated: Sep 17, 2026
Experimental Melanoma Immunotherapy Model Using Tumor Vaccination with a Hematopoietic Cytokine
Published on: February 24, 2023
Photodynamic immune stimulation eradicates primary pigmented melanoma and induces long-lasting anti-tumor immunity
L Pires1, C Calcada2, B Cerqueira-Rodrigues3
1Texas A&M University, Department of Biomedical Engineering, College Station, TX, USA. lpires@tamu.edu.
Background:
Melanoma is highly aggressive with limited options in advanced disease. Photodynamic therapy (PDT) has shown poor efficacy in pigmented melanoma due to restricted light penetration and intrinsic ROS resistance. A novel approach is investigated here.
Methods:
Full-thickness (4 mm) S91 pigmented melanoma grown intradermally in syngeneic immunocompetent (DBA) mice was treated using dual photosensitizers targeting tumor cells and microvasculature, together with a topical optical clearing agent. Anti-tumor immune effects were investigated in multiple functional assays, and the mechanisms-of-action were explored.
Results:
Primary tumor was eradicated in all mice, with 95% disease-free survival at 90 d, falling to 20% upon CD8 + T-cell depletion pre-treatment. The median survival in nude mice was 21 d. Treated DBA mice also rejected systemic tumor re-challenge at 30 d post treatment. There was delayed growth of untreated contralateral tumors and of tumors co-injected into naïve mice together with splenocytes from treated mice. Biomarker analysis showed rapid tumor infiltration by CD8+ and CD3+ T cells, reduced suppressive myeloid populations, and widespread immune activation. Gene expression profiling revealed enrichment of immune-related pathways and long-lasting memory.
Conclusions:
Photodynamic immune stimulation treatment can destroy primary pigmented melanoma far beyond the depth of light penetration and has potent anti-tumor systemic efficacy.
