SUMMARY/ABSTRACT In this SBIR grant proposal, “Development of a prototype clinical theranostic platform combining Magnetic Particle Imaging (MPI) and Magnetic Fluid Hyperthermia (MFH) for the treatment of brain tumors” we will develop a human brain-sized, integrated localized MFH/MPI system. We will develop an imaging-guided MFH treatment device capable of closed-loop localized heating and tomographic temperature monitoring during treatment. MFH relies on the delivery of magnetic nanoparticles to tumors followed by application of alternating magnetic fields, which causing local heating of tissue and killing of tumor cells. Cell death occurs due to the heat or by enhancing the cytotoxic effects of radio/chemotherapy. MFH offers considerable potential for numerous biomedical applications, especially as an adjunct to radiation therapy in the clinical treatment of recurrent glioblastoma. However, MFH currently suffers from limitations that persist after nearly four decades of clinical experience and regulatory approval in Europe. Following delivery, the nanoparticle distribution within the tumor can be heterogeneous and unpredictable, leading to undertreatment in areas of low MNP concentration, and excessive heating near normal tissues. These issues are compounded by a limited ability to accurately monitor tissue temperature in 3D and in realtime. The technology developed in this SBIR constitutes a paradigm shift for MFH by developing the first human- sized localized MFH system. Localized MFH is a new technology that uses strong magnetic field gradients to confine MNP heating to a small region. Particles within the region can generate heat, while those outside the region cannot. Our technology will transition clinical MFH from the current state of the art of loosely targeted, regional heating to mm-accurate localized heating of target tissues. We believe this transition from regional to precisely targeted is comparable to the transition of early, loosely targeted radiation therapy to the present day, 3D-targeted intensity-modulated radiation therapy. In this Direct to Phase II SBIR proposal, we will add MFH to our existing clinical-scale MPI prototype to enable localized MPI/MFH with integrated temperature sensing, and validate the performance in animal cadavers through the following specific aims: Aim 1. Build a clinical RF heating head coil for simultaneous MFH and imaging and integrate it into our prototype clinical imager Aim 2. Integrate MPI-based temperature sensing with heating to control MFH to a treatment plan. Aim 3. Test overall system in phantoms and animal cadavers in preparation for preclinical trials in dogs At the end of this Direct to Phase II proposal, we will have demonstrated integrated MPI/MFH for precisely localized image-guided therapeutic heating in a prototype that is suitable for clinical studies. In our future work, we plan to test this system in a large animal trial at JHU for treatment of spontaneous canine GBM.