Fang-Chu Lin, Chao-Hsiung Hsu, Yung-Ya Lin

Nano-therapeutic utilizing hyperthermia therapy in combination with chemotherapy, surgery, and radiation is known to treat various types of cancer. These cancer treatments normally focus on reducing tumor burden. Nevertheless, it is still challenging to confine adequate thermal energy in a tumor and obtain a complete tumor ablation to avoid recurrence and metastasis while leaving normal tissues unaffected. Consequently, it is critical to attain an alternative tumor-killing mechanism to circumvent these challenges. Studies have demonstrated that extracellular heat shock proteins (HSPs) activate antitumor immunity during tumor cell necrosis. Such induced immunity was further shown to assist in regressing tumor and reducing recurrence and metastasis. However, only a narrow range of thermal dose is reported to be able to acquire the optimal antitumor immune outcome. Consequently, it is crucial to understand how extracellular HSPs are generated. In this work, a predictive model integrating HSP synthesis mechanism and cell death model is proposed to elucidate the HSP involvement in hyperthermia cancer immune therapy and its relation with dead tumor cells. This new model aims to provide insights into the thermally released extracellular HSPs by dead tumor cells for a more extensive set of conditions, including various temperatures and heating duration time. Our model is capable of predicting the optimal thermal parameters to generate maximum HSPs for stimulating antitumor immunity, promoting tumor regression, and reducing metastasis. The obtained nonlinear relation between extracellular HSP concentration and increased dead cell number, along with rising temperature, shows that only a narrow range of thermal dose is able to generate the optimal antitumor immune result. Our predictive model is capable of predicting the optimal temperature and exposure time to generate HSPs involved in the antitumor immune activation, with a goal to promote tumor regression and reduce metastasis.