Single Center Experience Utilizing Pulse Electrical Field Ablation With and Without Concurrent Immunotherapy as Salvage Therapy

Immunotherapy is a promising therapeutic option for cancer {1;2}, but not all patients respond to immunotherapy alone {3}. Pulsed electric field ablation (PEF) is a novel non-thermal ablation modality inducing cell death through irreversible electroporation. Tumoral neoantigens and damage-associated molecular patterns are subsequently released stimulating the immune response against tumor both locally and distally through an abscopal effect as seen in pre-clinical models {4}. PEF does not alter the tumor antigens which allows an increased adaptive immune response {5;6}. Early clinical trial data has been promising {7}; however, there is limited clinical data on combined therapy with PEF and immunotherapy. This study evaluates the safety, feasibility and early outcomes of PEF to treat metastatic disease as salvage therapy with and without immunotherapy at a single center.

Materials and Methods:

Adult metastatic cancer patients not responding to prior treatments were identified. All PEF patients were discussed at multidisciplinary tumor board. Immunotherapy regimen was determined by the referring oncologist. PEF was performed by an experienced interventional radiologist using the Aliya PEF system (Galvanize Therapeutics, Redwood City, CA). Technical success was defined as complete delivery of energy into the targeted tumor. Device related and periprocedural adverse events were classified per the Society of Interventional Radiology Adverse Event classification {8}). Post procedure imaging follow up was directed by the oncology clinic to assess for local and systemic tumoral response using RECIST criteria. Detailed statistical analysis was used to analyze the collected data.

Results:

A total of 16 patients (10:6 male:female; age range 36-83 years old) were treated in 18 PEF sessions with eight on concurrent immunotherapy. Average treated lesion size was 2.9 cm (median 1.8 cm) primarily in lung and liver with between 1 and 12 activations performed (average 4). Technical success was 100% with no major adverse events. Majority of minor and moderate adverse events were pneumothorax in lung ablations. On imaging to date (up to 8 months, average 5.1 months), there was an approximately 30% response rate. All patients with decreased systemic tumor burden were on immunotherapy.

Conclusion:

PEF is safe and feasible as salvage therapy in patients with and without concurrent immunotherapy and may be a promising adjunct to immunotherapy. Further follow up and additional studies are needed to better delineate patients that best respond to these therapies with an abscopal effect.