This is multicentre, open-label, single-arm phase II study that investigates the feasibility, safety, tolerability, preliminary efficacy, costs, and pharmacokinetics or repetitive electrostatic pressurised intraperitoneal aerosol chemotherapy (ePIPAC-OX) as a palliative monotherapy for patients with isolated unresectable colorectal peritoneal metastases.

Rationale: repetitive electrostatic pressurised intraperitoneal aerosol chemotherapy with oxaliplatin (ePIPAC-OX) is offered as a palliative treatment option for patients with isolated unresectable colorectal peritoneal metastases (PM) in several centres worldwide. However, little is known about its feasibility, safety, tolerability, efficacy, costs, and pharmacokinetics in this setting.

Objectives: to prospectively explore the feasibility, safety, tolerability, preliminary efficacy, costs, and pharmacokinetic profile of repetitive ePIPAC-OX as a palliative monotherapy for isolated unresectable colorectal PM under controlled circumstances.

Study design: multicentre, open-label, single-arm, phase II study.

Setting: two Dutch tertiary referral hospitals for the surgical treatment of colorectal PM.

Study population: adults who have a World Health Organisation (WHO) performance status of 0 or 1, adequate organ functions, histologically or cytologically confirmed unresectable PM of a colorectal or appendiceal carcinoma, no systemic metastases, no symptoms of gastrointestinal obstruction, no contraindications for the planned intervention, and no previous pressurised intraperitoneal aerosol chemotherapy (PIPAC).

Intervention: instead of standard palliative treatment, enrolled patients receive laparoscopy-controlled ePIPAC-OX (92 mg/m2 body-surface area [BSA]) with intravenous leucovorin (20 mg/m2 BSA) and bolus 5-fluorouracil (400 mg/m2 BSA) every six weeks. Four weeks after each procedure, patients undergo clinical, radiological, and biochemical evaluation. ePIPAC-OX is repeated until clinical, radiological, or macroscopic disease progression, after which standard palliative treatment is (re)introduced.

Outcomes: the primary outcome is the number of patients with major toxicity (grade ≥3 according to the Common Terminology Criteria for Adverse Events v4.0) up to four weeks after the last procedure. Secondary outcomes are the environmental safety of ePIPAC-OX, procedure-related characteristics, the number of procedures in each patient and reasons for discontinuation, minor toxicity, organ-specific toxicity, postoperative complications, hospital stay, readmissions, quality of life, costs, progression-free survival, overall survival, and the radiological, histopathological, cytological, biochemical, and macroscopic tumour response. Atomic absorption spectrophotometry is used to measure concentrations of oxaliplatin in plasma, plasma ultrafiltrate, urine, ascites, PM, and normal peritoneum during and after ePIPAC-OX.

Eligible patients are adults who have:

• a World Health Organisation (WHO) performance status of ≤1;
• histological or cytological proof of PM of a colorectal or appendiceal carcinoma;
• unresectable disease determined by abdominal computed tomography (CT) and a diagnostic laparoscopy or laparotomy;
• adequate organ functions (haemoglobin ≥5.0 mmol/L, neutrophils ≥1.5 x 109/L, platelets ≥100 x 109/L, serum creatinine <1.5 x ULN, creatinine clearance ≥30 ml/min, and liver transaminases <5 x ULN);
• no symptoms of gastrointestinal obstruction;
• no radiological evidence of systemic metastases;
• no contraindications for oxaliplatin or 5-fluorouracil/leucovorin;
• no contraindications for a laparoscopy;
• no previous PIPAC-procedures.

Enrolled patients are excluded from the analyses in case they did not receive a first ePIPAC-OX, e.g.:

• due to systemic metastases on baseline thoracoabdominal CT, or;
• due to non-access during first ePIPAC-OX, or;
• due to resectable disease during first ePIPAC-OX.

Importantly, enrolment is allowed for patients with an unresected primary tumour (if asymptomatic) and for patients in various lines of palliative treatment, including patients who refuse, have not had, or do not qualify for first-line palliative systemic therapy. All potentially eligible patients are discussed by a multidisciplinary team. Enrolled patients are informed about the potential consequences of postponing or discontinuing standard palliative treatment by a medical oncologist prior to enrolment.

Available on request

End of the study

Available on request