A Single Institutional Experience with Pulsed Electric Field Ablation in the Treatment of Patients with Localized and Metastatic Cancer

Pulsed electric field (PEF) ablation uses nonthermal energy to disrupt cell membrane integrity resulting in immunogenic tumor cell death. Systemic immune activation has potential to impact nontarget tumor growth through abscopal effects. Our study examined the safety profile and short-term efficacy of PEF ablation in patients with localized and metastatic cancers, and its effects on both target and non-target lesions.

Materials and Methods:

This IRB-approved single institution retrospective study examined 20 patients who underwent CT or US-guided PEF ablation of one or more soft tissue lesions with the Aliya System (Galvanize Therapeutics, CA) from 09/2022 to 08/2024. Patient demographics, procedure details, tumor size, concurrent systemic therapy, complications, and follow up imaging were reviewed. Adverse events were classified according to SIR guidelines.

Results:

A total of 31 lesions were ablated in 24 sessions. Primary cancers included soft tissue sarcomas (6), non-small cell lung cancer (6), colorectal adenocarcinoma (3), thymoma (1), cholangiocarcinoma (1), mesothelioma (1), squamous cell carcinoma (1), and melanoma (1). Median patient age was 62 (13-81) years and 15/20 (75%) were female. 15/20 (75%) patients were on chemotherapy and 3/20 (15%) were on immunotherapy. Mean target tumor size was 2.0 (0.6-7.7) cm. 19/31 lesions were in the lung, 6/31 in superficial soft tissue, 4/31 in the retroperitoneum, and 2/31 in the liver. PEF ablation was performed with 100 pulse packets at 3000 V for 5 minutes per cm of tumor in overlapping fashion. One ablation session had to be terminated early due to stimulation of the cough reflex which could not be abrogated by probe repositioning. The remaining 23 sessions were technically successful. 1/24 (4%) sessions had a major adverse event (pneumothorax requiring hospitalization, chest tube, and blood patch), 2/24 (8%) had moderate adverse events (pneumothorax requiring chest tube), and 21/24 (88%) had no adverse event. Post-ablation mean follow-up time was 121 days (range 29-452 days). Of the target lesions, 3/31 decreased in size in the follow up interval, 19/31 remained stable, 3/31 increased in size, and 6/31 lesions had insufficient follow up available to assess response. Of 14 patients with measurable off target lesions, in 11/14 patients, the lesions decreased or remained stable in size, and 3/14 increased in size.

Conclusion:

PEF ablation is a promising non-thermal form of tumor ablation with relatively low adverse events. Extended follow up of larger cohorts are needed to characterize long-term efficacy and putative abscopal effects.