Early Patient Outcomes After Liver Tumor Histotripsy

Histotripsy is a novel non-invasive ablation technology that mechanically destroys tumor tissue through acoustic cavitation, with reports of nontarget (abscopal) immune responses. This study aims to characterize the preliminary safety and efficacy of histotripsy for malignant liver tumors, including abscopal responses.

Materials and Methods:

A single-center database of all patients who underwent histotripsy for liver tumors from February to August 2024 was compiled. Demographic, clinical, imaging, procedural, and follow-up data were documented via chart review. 30-day adverse events were categorized according to the SIR adverse event classification system (1). 1-month follow-up cross-sectional imaging was evaluated for treatment response. 

Results:

Histotripsy was performed upon 43 liver tumors in 23 patients (57% female, age 64 + 13y) with stage 4 cancer (47.8% pancreatic adenocarcinoma, 21.7% colorectal adenocarcinoma). 91.3% of patients were on concurrent systemic therapy. All patients were discharged within 36 hours of the procedure. 1-month follow-up imaging was available for 12/23 (52.2%) patients: global progression of disease was seen in 33.3%, stable disease/mixed response to treatment was seen in 58.3%, and a global decrease in tumor burden, including nontarget lesions, was seen in 1 (8.3%) colorectal cancer patient after treatment of 2 lesions. The patient who demonstrated a global response had discontinued cytotoxic therapy prior to histotripsy but was continuing EGFR inhibition. Adverse events were mild and included two cases of skin irritation, and two cases of postoperative urinary retention requiring temporary catheterization. No deaths occurred within 30 days. 

Conclusion:

One patient with metastatic colorectal cancer experienced a robust potential abscopal response after histotripsy of liver metastases; such effects appear rare and predictors require further characterization. Liver tumor histotripsy is safe with a minimal adverse event profile.