Quantitative evaluation of focused ultrasound thermal therapy on immunogenic cell death in breast cancer

Triple negative breast cancer (TNBC) is resistant to conventional therapies, leading to poor disease-free survival and high recurrence rates. However, in contrast to other breast cancers, TNBCs have more tumor infiltrating lymphocytes making them a suitable target for immunotherapy. While immune checkpoint inhibitors

in combination with chemotherapy, radiation therapy and other immunotherapy drugs have demonstrated clinically relevant improvements in overall response rates for TNBC patients, response is still limited to a subset of patients. Over the past decade, immunogenic cell death (ICD) has been recognized as an imperative

step for anti-tumor immunity. ICD is a specific cell death pathway that is induced by cellular stress, resulting in the exposure or secretion of several damage-associated molecular patterns and cytokines which facilitate the cross-presentation of tumor antigens to CD8+ T cells. ICD induction has become an increasingly popular

treatment option for combination therapies with preclinical and clinical studies demonstrating that chemotherapy can act as an ICD inducer for TNBCs. However, new ICD inducers are needed to combat systemic toxicities and oncogenic side effects of chemotherapy. Focused ultrasound (FUS) is a non-toxic,

non-ionizing, readily clinically translatable option for non-invasive, targeted tumor destruction. Immunotherapy is an emerging application of FUS, and thermal FUS has been shown to induce release of intact tumor- associated antigens and heat-shock proteins, an indicator of ICD, in breast cancer. However, ICD induction

after thermal FUS application has not been thoroughly characterized as a function of thermal dose. This proposal will characterize the induction of ICD after FUS thermal treatment and investigate the mounting of adaptive immunity in a murine TNBC tumor model. Two thermal FUS mechanisms (hyperthermia and thermal

ablation) will be evaluated in two specific aims. Aim 1 will quantify ICD induction following thermal FUS with spatial registration of multiplex immunofluorescence to the MRI-derived thermal dose biomarker. Aim 2 will quantify the adaptive immune response following thermal focused ultrasound induced ICD. The successful

completion of the proposal will inform how thermal focused ultrasound can influence immunogenic cell death and subsequent adaptive immunity in a murine triple negative breast cancer model. The evaluated FUS exposures can readily be transferred to future clinical trials as the patient-specific treatment monitoring and

MRI-based thermal dose biomarker are already utilized in ongoing FUS breast cancer clinical trials.