HMGB1 and neoplasm: During PDT, cancer cell death promotes the extracellular release of DAMPs such as calreticulin protein, high mobility group box 1, and ATP, along with the exposure of tumor‐associated antigens.[115] These signals stimulate the maturation of antigen‐presenting cells, such as DCs, and activate T lymphocytes through inflammatory cytokine production, inducing immune‐mediated tumor eradication.[116] Combining PDT with chemotherapy further enhances ICD stimulation.