PDT-induced anti-tumor immunity

The ideal cancer treatment should target both the primary tumor and the metastases with the minimal toxicity. This is best accomplished by educating the body's immune system to recognize the tumor as foreign so that after the primary tumor is destroyed, distant metastases will also be eradicated. PDT may accomplish this feat and stimulate long-term, specific anti-tumor immunity. PDT causes:

an acute inflammatory response,
the rapid induction of large amounts of necrotic and apoptotic tumor cells, induction of immunostimulatory heat-shock proteins
tumor antigen presentation to naïve T-cells
generation of cytotoxic T-cells that can destroy distant tumor metastases. 

By using various syngeneic mouse tumors in immunocompetent mice, we can study specific PDT regimens related to tumor type, the synergistic combination of low-dose cyclophosphamide and PDT, and PDT combined with immunostimulants (toll-like receptor ligands) to maximize the generation of anti-tumor immunity. The use of tumors expressing defined tumor associated antigens with known MHC class I peptides allows anti-tumor immunity to be quantitatively compared.

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