This study is an investigator-initiated, randomized controlled trial enrolling patients with colorectal liver metastases. The objectives are to evaluate the safety and efficacy of contrast-enhanced ultrasound (CEUS)-mediated sonoporation as a potential therapeutic intervention and to investigate whether sonoporation can modulate the tumor microenvironment toward a more immune-active state

The trial is designed as an investigator-initiated, multicenter, prospective, randomized, controlled, two-arm, intervention trial with a matched historical control group aims to evaluate the therapeutic potential of contrast-enhanced ultrasound (CEUS) in patients with colorectal liver metastases (CLM). The primary objectives are to assess whether CEUS can modulate the tumor microenvironment and to determine the safety, tolerability, and feasibility of CEUS as a therapeutic modality. Eligible patients will be randomized to receive either low-intensity CEUS (LI-CEUS) or high-intensity CEUS (HI-CEUS) focused on a designated study metastasis. Safety, feasibility, and success-rate of the intervention will be registered. Minimum seven days post-intervention a biopsy of the study metastasis will be conducted. Subsequent analyses will compare immune cell infiltration, immune-related gene expression, and stromal and vascular remodeling in LI-CEUS- and HI-CEUS-exposed metastases versus historical controls.

Inclusion Criteria:

• Adult patients (≥18 years)

• Ability to provide written informed consent

• Histopathological confirmed colorectal adenocarcinoma

• Scheduled for liver resection or ablation at the Rigshospital, or admitted to oncologic treatment due to colorectal liver metastases (CLM) at Zealand University Hospital

• Presence of at least one CLM evaluable and accessible by CEUS

• Eastern Cooperative Oncology Group (ECOG) performance status of 0-2.

• Follow the conditions regarding fertility, pregnancy, or lactation:

  • Women of childbearing potential (WOCBP) are defined as women ranging from the period of menarche till the post-menopausal period, unless permanently sterile (e.g. hysterectomy, bilateral salpingectomy and bilateral oophorectomy), Post-menopause is defined as no menses for 12 months without an alternative medical cause.
  • WOCBP should use a secure and highly effective birth control (as stated in the "Recommendations related to contraception and pregnancy testing in clinical trials", version 1.1, section 4.1, from the Clinical Trials Facilitation and Coordination Group) during the entire period of the trial. In cases of uncertainty regarding pregnancy, pregnancy testing either as highly sensitive serum or urine pregnancy test will be used.

Exclusion Criteria:

• Oncologic systemic treatment 2 weeks prior to inclusion

• Prior treatment with an immune checkpoint inhibitor (e.g. anti-PD-L1, anti PD-1, or anti-PD-L2)

• Inability to reliably distinguish the study metastasis from other hepatic metastases using CEUS

• Systemic treatment with either corticosteroids (>10 mg daily prednisolone equivalents) or other immunosuppressive medications within 2 weeks prior inclusion. Inhaled or topical steroids and adrenal replacements doses > 10 mg daily prednisone equivalents are permitted in the absence of active autoimmune disease.

• Known history of human immunodeficiency virus (HIV), active or chronic hepatitis B, or C.

• Pregnancy or lactation.

• Confirmed dMMR positive primary tumors

• Inability to comply with study protocol due to psychological, social, or logistical reasons.

• Contraindications for CEUS:

  • Known hypersensitivity to SonoVue® or any other ultrasound contrast agent
  • Uncontrolled atrial hypertension
  • Known right-to-left intracardiac shunt
  • Severe pulmonary hypertension (SAP >90 mmHg)
  • Adult respiratory distress syndrome.
  • Known hypersensitivity to macrogols
  • Unstable ischemic heart disease or acute coronary syndrome
  • Severe lung disease, e.g. severe chronic obstructive lung disease

It is not yet decided.