Abstract No. 354 Early Experience of Novel Pulsed Electric Field Ablation in Patients with Metastatic Cancer

As interventional oncology treatments expand, we report our early experience with pulsed electric field (PEF) ablation for metastatic disease. This treatment modality utilizes a single-probe technique to promote malignant tumor antigen upregulation, allowing for immunotherapy treatments to take advantage of potential abscopal effects. Our study includes patients with metastatic fibrolamellar carcinoma (FLC) and osteosarcoma (OS), including local and distant treatment responses and safety. 28 patients with metastatic FLC or OS patients at Rush University Medical Center in Chicago, IL who underwent PEF with the Aliya System (Galvanize Therapeutics, Inc.) were included. Target lesions were treated under CT guidance. Non-target lesions were known metastatic foci that were not directly ablated by PEF. Responses were classified with RECIST 1.1. There were 8 FLC patients with 21 unique lesions treated with PEF ablation in 14 separate interventions. Including retreated lesions, 32 total lesions treated. Lesion locations: chest (47%) and abdomen (53%). Due to lack of follow up imaging, 12 lesions were excluded. Target lesions were found to have partial response (PR) in 5%, stable disease (SD) in 80%, and progressive disease (PD) in 10%. Of note, one (5%) of the target lesions demonstrated pseudoprogression. Local control rate (LCR) defined as complete response (CR) + PR + SD over total treated lesions was 85%. There were 15 non-target lesions, of which 73.3% demonstrated SD and 26.7% demonstrated PD. Mean follow up time for the FLC cohort was 78.5 days. There were 3 OS patients with 8 unique lesions treated with PEF ablation in 5 separate interventions, all within the thorax. Two lesions were excluded due to lack of follow up imaging. Targeted lesions demonstrated SD in 83.3% and PD in 16.7% lesions. LCR was 83.3%.Two OS patients demonstrated non-targeted lesion treatment response in 62.5% lesions between 3-5 months post-PEF. However, despite non-target response, new metastatic lesions developed in these patients, resulting in classification of PD. Mean follow up time for the OS cohort was 125.3 days. Complications were limited to a trace pneumothorax in the OS cohort and none in the FLC cohort. PEF is a safe ablative technology with promising LCR in this short-term evaluation. Further evaluation with larger and more robust cohorts is necessary. Given our preliminary review, PEF ablation may be a viable treatment adjunct for patients with metastatic FLC and OS.