Enhancing the abscopal effect of radiation and immune checkpoint inhibitor therapies with magnetic nanoparticle hyperthermia in a model of metastatic breast cancer.
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ABSTRACT: Purpose: Enhancing immune responses in triple negative breast cancers (TNBCs) remains a challenge. 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.Methods: 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 (HTM, 43?°C/20?min) or partially ablative (HTAbl, 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. Two weeks after treatment, lungs and livers were harvested for histopathology evaluation of metastases.Results: Compared to untreated controls, all treatment groups demonstrated a decreased tumor volume; however, when compared against surgical resection, only RT?+?HTM+IT, RT?+?HTAbl+IT and RT?+?HTAbl had similar or smaller tumors. These cohorts showed more infiltration of CD3+ T-lymphocytes into the primary tumor. Tumor growth effects were partially reversed with T-cell depletion. Combinations that proved most effective for primary tumors generated modest reductions in numbers of lung metastases. Conversely, numbers of lung metastases showed potential to increase following HT?+?IT treatment, particularly when compared to RT. Compared to untreated controls, there was no improvement in survival with any treatment.Conclusions: Single-fraction MION HT added to RT?+?IT improved local tumor control and recruitment of CD3+ T-lymphocytes, with only a modest effect to reduce lung metastases and no improvement in overall survival. HT?+?IT showed potential to increase metastatic dissemination to lungs.
SUBMITTER: Oei AL
PROVIDER: S-EPMC7017719 | biostudies-literature | 2019 Nov
REPOSITORIES: biostudies-literature
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