Project Abstract Metastatic breast cancer (BrCa) is the 2nd most prevalent cause of cancer mortality in women in the United States, with a 5-year overall survival of only 22%. Though cancer immunotherapies are capable of generating durable responses across a variety of cancer types, immunologic rejection of BrCa is rare and spontaneous regression unusual. Thus, there exists a strong precedent for allied combinatorial therapy paradigms that potentiate immunotherapy (ITx) by boosting tumor immunogenicity and/or curbing immunosuppressive mechanisms. In this proposal, we will systematically assess the capacity of focused ultrasound (FUS) - a technique for non-invasive, non-ionizing acoustic energy deposition into tumors – to potentiate adaptive immunity against BrCa metastases and synergize with selected immunotherapies. UVA is a world leader in FUS ITx research, with two “first-in-human” clinical trials underway to evaluate combinations of FUS with PD1 blockade in solid tumors (including metastatic BrCa) and a third trial pending approval to evaluate FUS and gemcitabine for immune-mediated control of BrCa tumors. These trials are accompanied by a companion imaging trial designed to evaluate CD8+ T cell infiltration in patients’ tumor deposits via PET/CT, an approach that will also be integrated into our pre-clinical studies. To this end, this proposal leverages these clinical trials as well as a robust pre-clinical program to fortify a highly translational research pipeline rooted in the domains of immunology, molecular imaging, liquid biopsy and radiogenomics. With this toolkit, we intend to design and implement FUS+ITx combinations that offer the potential for quantum improvements in metastatic BrCa therapy. This is achieved in three Specific Aims. In Specific Aim 1, we will expand on intriguing early clinical and pre-clinical findings to identify FUS regimens that, when combined with myeloid-targeted therapies, augment the efficacy of chimeric antigen receptor (CAR) T cell therapy against primary and disseminated BrCa tumors (e.g. brain metastases). In Specific Aim 2, we will engineer FUS-based theranostic technologies for liquid biopsy in BrCa in order to (i) discover novel biomarkers of response to FUS and ITx (ii) enable liquid biopsy in settings with low basal levels of circulating tumor biomarkers. Finally, in Specific Aim 3, we will construct machine learning frameworks that integrate radiological data with genomic data from liquid biopsy specimens (e.g. radiogenomics) to advance BrCa precision care with FUS and ITx. The highly innovate aims of this proposal lend to a systematic approach for advancing the role of FUS in CAR T cell therapy, cancer biomarker discovery and personalized ITx, thereby promising to improve the lives of metastatic breast cancer patients.

Project Narrative For the significant fraction of metastatic breast cancer patients that are yet unable to realize the unparalleled benefits of cancer immunotherapy, focused ultrasound (FUS) is poised to play a transformative role - owing to its diverse capacity for destroying solid tumor tissue, enhancing drug delivery and promoting anti-tumor immune response. The goal of this proposal is to design and deploy rational combinations of FUS and immunotherapy in primary and disseminated breast cancers (with special emphasis on CAR T cell therapy), as well as to develop non-invasive tools for monitoring and individualizing these combinations through the use of innovative approaches in molecular imaging, liquid biopsy and radiogenomics. The highly translational structure of this proposal offers the potential for quantum improvements in metastatic breast cancer prognosis and therapy and meanwhile ushers FUS into the burgeoning era of precision immuno-oncology.