Most ablation technologies destroy tumors with heat — radiofrequency ablation (RFA), microwave ablation, laser ablation, and thermal focused ultrasound all work by cooking tumor tissue to temperatures that kill cells. Histotripsy works differently. It uses microsecond-long pulses of focused ultrasound energy at very high pressure to generate acoustic cavitation — the rapid formation and collapse of microbubbles within tissue — that mechanically liquefies cells into an acellular slurry, leaving surrounding structures intact. No heat. No incision. No ionizing radiation. And a unique immune effect that may extend its benefit beyond the treated tumor.
The FDA Clearance: What It Covers
The FDA cleared HistoSonics' Edison System for non-invasive destruction of liver tumors in October 2023 — the first non-thermal ablation technology cleared for any solid tumor. The 510(k) clearance covers primary and metastatic liver tumors ≤3cm that are accessible to ultrasound from the abdominal surface, in patients not eligible for resection or thermal ablation. In 2026, the system is operational in 38 centers in the US and 22 in Europe.
HOPE4LIVER Trial: The Pivotal Data
The HOPE4LIVER IDE trial enrolled 44 patients with liver tumors (HCC and colorectal liver metastases) treated with the Edison System. Published in The Lancet Gastroenterology & Hepatology in late 2025:
- Technical success: Complete treatment in 39 of 44 patients (88.6%); failures were due to tumor depth or rib shadowing
- Local tumor control at 6 months: 72% complete ablation by MRI; 18% partial response; 10% progression
- Serious adverse events: 5 events in 4 patients (9.1%); all were minor liver enzyme elevations without clinical sequelae
- No deaths attributable to treatment
- Hospital stay: Median 1 day (outpatient in 24%)
These results compare favorably to RFA (local control 80–90% in tumors <3cm) without the anesthesia, percutaneous access, and heating-related complications of thermal ablation.
The Abscopal Effect: Immune Activation Beyond the Tumor
The most intriguing aspect of histotripsy is a potential abscopal effect — tumor responses outside the treated field. When histotripsy liquefies a tumor, it releases tumor-associated antigens in a pro-immunogenic context (mechanical lysis, not apoptosis) that may activate anti-tumor immunity. In a murine model, histotripsy of a primary tumor delayed growth of untreated contralateral tumors. In a case series of 8 patients with colorectal liver metastases, 3 showed partial response in non-treated metastases at 3-month imaging — findings consistent with, though not confirmatory of, immune activation.
HistoSonics has partnered with Memorial Sloan Kettering to conduct a planned trial combining histotripsy with checkpoint immunotherapy (pembrolizumab) in liver metastases, specifically designed to test and amplify this immune synergy.
Expanding Indications: Pancreas, Kidney, Prostate
IDE applications for pancreatic cancer (palliative debulking), renal cell carcinoma, and focal prostate cancer are in various stages of review or early-stage clinical trial. The pancreas application is technically challenging due to bowel gas interference; specialized bowel prep protocols are being refined to improve targeting consistency.
Conclusion
Histotripsy is a fundamentally new tool in the oncologic ablation armamentarium — one that works by a different physical mechanism, potentially triggers immune activation, and can be performed with minimal patient recovery burden. As center experience grows and indication expansion proceeds, this technology has the potential to shift the boundary of what "non-surgical" cancer treatment can achieve. Healthcare facilities can find relevant diagnostic equipment in our catalog.
