Project Summary / Abstract An estimated 34,000 patients are diagnosed in the US with primary liver each year with a substantially larger number of patients will developing liver metastasis from a broad range of primary tumor sites. Unfortunately, the vast majority of these patients are not candidates for surgical resection, which is the only reliably curative treatment for liver tumors, yielding a five year survival rate of approximately between 10 and 20% for patients with primary disease. The primary clinical challenge is that most tumors form deep within organs, near major blood vessels, bile ducts, or nerves which complicate surgical removal and contraindicate other first line treatments. Phased Algorithmically Controlled Electrotherapy (PACE) is a new minimally invasive technique developed by the Gradient Medical for the treatment of inoperable tumors which uses ultrashort high intensity electrical pulses to destabilize the cell membrane and induce a tunable combination of necrotic and apoptotic cell death. In this proposal we investigate the feasibility of this approach for the treatment of liver tumors through two specific aims: 1) Characterization of Selective Targeting with ACE protocols. 2) Development of a Multiphase Alternating Polarity Pulse Generation System. In the proposed study Gradient Medical will design and build a novel pulse generation system which enables instantaneous electrical energy delivery between up to four synchronized temperature sensing applicators. Feasibility of this approach will be demonstrated using a benchtop perfused liver model which enables direct visualization of the treatment zones created by the non- thermal pulsed electric field mediated cell death mechanisms. Preliminary safety and in vivo efficacy will be evaluated in an in vivo large animal liver model. The results from this feasibility study will be used to generate preliminary treatment planning algorithms necessary for subsequent Phase II in vivo safety and efficacy studies against spontaneous liver tumors in veterinary patients.