Our study aimed to determine whether magnetic iron oxide nanoparticle (MION) hyperthermia (HT) can enhance abscopal effects with radiotherapy (RT) and immune checkpoint inhibitors (IT) in a metastatic TNBC model.<b>Methods:</b> One week after implanting 4T1-luc cells into the mammary glands of BALB/c mice, tumors were treated with RT (3 × 8 Gy)±local HT, mild (HT<sub>M</sub>, 43 °C/20 min) or partially ablative (HT<sub>Abl</sub>, 45 °C/5 min plus 43 °C/15 min),±IT with anti-PD-1 and anti-CTLA-4 antibodies (both 4 × 10 mg/kg, i.p.).Tumor growth was measured daily.
When combined with anti-CTLA-4 antibody, the biomimetic and biodegradable nanoparticle enables the notable eradication of primary and deeply metastatic tumors with low systematic toxicity, thus potentially advancing the development of combined hyperthermia, PDT, and checkpoint blockade immunotherapy to combat cancer metastasis.