Short summary

We hypothesize that the PIPAC procedure is feasible and safe in high-risk GAC patients undergoing laparoscopic D2 gastrectomy. 

The primary aim is to investigate whether PIPAC, delivered immediately after laparoscopic D2 gastrectomy, can be performed as a safe procedure in patients with high-risk GAC.

Rationale

Gastric adenocarcinoma (GAC) is considered the fifth most common cancer in the world (1,313,000 cases per year) and the third leading cause of cancer death globally (819,000 deaths per year). Its incidence varies according to the region with a low incidence in the West. In East Asia, especially Japan and Korea, the incidence of distal GAC is high, whereas proximal GAC has a higher incidence in the West. According to the American Joint Committee on Cancer 8 (AJCC 8), gastroesophageal junction adenocarcinomas that have epicentre in the proximal 2 to 5 cm of the stomach (Siewert type III) should be staged and treated as GAC.

The consensus is that, in Western countries, medically fit GAC patients should undergo D2 gastrectomy, which is carried out in specialised, high-volume centres with appropriate surgical expertise and postoperative care. As a result, perioperative outcome is standardised with morbidity and mortality rates of 15% and 3%, respectively. The concept of "enhanced recovery" encompasses all aspects of optimal perioperative care for patients undergoing gastrectomy.

Significant progress has been made regarding the definition of risk factors for GAC resulting in implementation of preventive strategies and curative treatment of premalignant and early neoplastic lesions. Nevertheless, the majority of GAC patients presents with advanced stages of disease leading to a dismal prognosis even after treatments with curative intent. Clinical research during the latest decade has explored and documented the concept of perioperative chemotherapy in GAC and cancers originating in the distal esophagus and GEJ. However, it seems that the tumours most responsive to these regimens are those originating in the esophagus and GEJ. Moreover, GACs dominated by signet ring cells have been found to be basically resistant to any chemotherapy regimen, and this type is particularly frequent in countries with high incidence of cancers originating in the distal esophagus and GEJ. Concerning GAC, another group of patients with an extremely poor prognosis is those with malignant cells retrieved from peritoneal lavage before surgery. Accordingly, laparoscopy with peritoneal washings for malignant cells is recommended in all stage IB-III gastric cancers which are considered potentially resectable, to exclude radiologically occult metastatic disease; the benefit may be greater for patients with T3/T4 disease.

Irrespective of these tumours' origin, the peritoneum is one of the most frequent sites of metastases and recurrences that generally determines the subsequent prognosis. Additionally, it is observed that none of the currently available perioperative chemotherapy regimens have been able to reduce the risk for peritoneal deposits.

It is commonly believed that peritoneal metastasis (PM) occurs through the deposition of tumour cells either by the direct extension and subsequent cellular exfoliation, or through the traumatic dissemination of cancer cells during surgery. Clinical validation of the concept of direct extension is also provided by observing the higher rate of PM seen with increasing tumour stages (T-stages) and with the incidence of serosal invasion. This is also supported by the fact that the rate of positive peritoneal cytology increases with tumour stage. 

It is also hypothesized that during gastrectomy, cancer cells present within the dissected lymphatic channels and blood vessels are scattered in the abdominal cavity, thereby contaminating the peritoneum. It has been demonstrated that 60% of lavage cytology-negative (Cyt-) patients will convert to a cytology-positive (Cyt+) state (determined by reverse transcription polymerase chain reaction, RT-PCR) immediately after gastrectomy. Free cancer cells can then attach to the peritoneal surface; a process facilitated by the action of cytokines that further the deposition of fibrin layers, entrapping those cells. This new restrictive milieu is thought to hinder the penetrance of drugs delivered systemically and provides grounds for the early administration of intraperitoneal treatments.

The intraperitoneal delivery and subsequent uptake of chemotherapy is improved by a new aerosol technique. Pressurized Intraperitoneal Aerosol Chemotherapy (PIPAC) has shown promising results in patients with PM from colorectal, ovarian and gastric cancer (see below), and it is feasible, safe and well tolerated by the majority of patients.

The first in human use of PIPAC was performed in Germany in 2011. The first studies showed that PIPAC directed treatment induced a histological response in a substantial number of patients and the survival data were encouraging. They further showed that the local (peritoneal) concentration of doxorubicin was high (?4.1 ?mol/g) while plasma concentration was reduced to a minimum (4.0-6.2 ng/ml). In a retrospective study, 24 patients with therapy-resistant PM from gastric cancer were scheduled for a total of 60 PIPAC procedures with 7.5 mg/m2 cisplatin and 1.5 mg/m2 doxorubicin. Seventeen patients had repeated procedures, and PIPAC was well-tolerated. Two in-hospital deaths were reported, but according to the authors these deaths were caused by disease progression, and were not related to the PIPAC procedure. Cumulative survival after one year was 52%, and the median overall survival was 15.4 months. 

Based on these data, it was decided to implement this new technique at Odense PIPAC Center (OPC), Odense University Hospital, Denmark. All PIPAC procedures at OPC have been investigated within the framework of clinical trials, and with the publication of the PIPAC-OPC1 trial in 2018, we showed that the procedure was safe and feasible in Danish patients with PM from various primary tumours. We also showed that PIPAC directed treatment induced a histological response in two out of three patients with no negative impact of their quality of life scores. 

Based on the results of the PIPAC-OPC1 study, we opened the ongoing PIPAC-OPC2 trial in late 2016 (EudraCT number 2016-003394-18). The PIPAC-OPC2 study is designed to investigate the histological treatment response in a large study population of 137 patients with PM, which allows relevant subgroup analyses stratified by cancer type.

Based on data from the German pioneer studies in PIPAC directed treatment, the empirical dose of 7.5 mg/m2 cisplatin and 1.5 mg/m2 doxorubicin has been used in both the PIPAC-OPC1 and OPC2 studies. These doses have been evaluated in a dose-escalation study, which showed that an increment of 20% was safe, hence the evidence-based dose in future studies should be 10.5 mg/m2 cisplatin and 2.1 mg/m2 doxorubici.

In a recent submitted paper, we assessed the outcome of PIPAC, with 7.5 mg/m2 cisplatin and 1.5 mg/m2 doxorubicin, in GAC patients with chemotherapy-resistant PM treated at OPC. Objective tumour response was documented in 40% of the patients after PIPAC, including complete histological regression in some, whereas an additional 20% had no further tumour progression (manuscript in preparation). These observations in GAC patients deliver further evidence suggesting that PIPAC can induce regression of resistant PMs in several cancer types and might meet the clinical need for new and better therapies for fatal cancer disease states. Our results also provide evidence that low-dose PIPAC therapy might be effective in treating patients with recurrent, chemo-resistant gastric PMs, including the aggressive signet-ring histology. 

The imminent question is whether PIPAC delivered immediately after a laparoscopic D2 gastrectomy for GAC, in patients being exposed to a significant risk of early recurrent disease, can be safely carried out? If so, for the first time, a corresponding therapeutic concept can be offered to similar GAC patients in addition to surgery with curative intent. This could potentially increase progression free and eventually overall survival. 

Description of the cohort

Patients (men and women +18 years of age) with high-risk GAC defined as: Diffuse cancer (signet ring cells predominant) or clinical stage: cTany + cN2-3 or cT3-T4 + cNany or GAC patients with preoperative positive peritoneal cytology submitted to laparoscopic gastrectomy (+/- neoadjuvant treatment).

Data and biological material

Peritoneal lavage (PL) is performed to monitor the rate of malignant cells before (PL-1) and after (PL-2) the laparoscopic D2 gastrectomy. This procedure is standardised and conducted as follows: five hundred ml of saline is administered into the peritoneal cavity via a standard irrigation and suction device with 100 ml delivered in the right subphrenic area, 100 ml in the right paracolic gutter, 100 ml in the left paracolic gutter, 100 ml in the epigastrium and 100 ml in the pelvis. Afterwards, the patient is rotated to the anti-Trendelenburg position and 200 ml saline is collected, and referred for cytological examination, while the remaining fluid is collected and disposed.  Before PL-2 is performed the intraabdominal cavity is cleared of blood, but otherwise both PLs are performed as described above. 

At the Departments of Pathology at Odense University Hospital, Denmark, and Karolinska Hospital, Stockholm, Sweden, the fluid will be processed as follows (22): If a spontaneous coagulum is present, it will be fixed in formalin and embedded in paraffin. Three centrifuge tubes will be filled with 50 ml of the fluid. The fluid in the tubes will be centrifuged. 

From the first tube, two smears will be produced from the sediment, dried and stained with Papanicolaou and May-Giemsa Grünwald. The sediment from the second tube will be stored at -80°C in MagNA Pure LC Lysis Buffer (Roche) for subsequent qRT-PCR expression analysis. From the sediment of the third tube, a cell block will be prepared after addition of three drops of plasma and two drops of thrombin. The cell block will be fixed in formalin and embedded in paraffin. From each of the two paraffin blocks, a 4-5 µm thick section will be cut with a microtome and stained with H&E for microscopic analysis. 

The cytological diagnosis will be based on the smears and the H&E stained sections from paraffin embedded cell block preparations and/or the spontaneous coagulum. If necessary, as judged by the pathologist based on the findings at conventional cytology, additional sections were cut from the paraffin embedded material and used for immunocytochemical analyses for tumor markers such as CEA, EpCAM, CDX2 and/or CK20 as well as markers for mesothelial cells, such as calretinin and vimentin. The specimens from both countries will be evaluated by the same pathologist (SDE) in Denmark. Each specimen will be classified as 1) no malignant cells, 2) atypical cells, 3) cells suspicious for malignancy or 4) malignant tumor cells. The cytological diagnosis will be considered positive if cells are suspicious for malignancy or malignant tumor cells are detected.

After analysis the remaining fluid collected are disposed.

Collaborating researchers and departments

Department of Surgery, Odense University Hospital: 

• PhD MD Signe Bremholm Ellebæk
• Prof. PhD MD Michael Bau Mortensen
• PhD MD Claus Fristrup
• PhD MD Alan Patrick Ainsworth
• PhD MD Michael Hareskov Larsen
• MD Martin Graversen
• MD Anna Pilegaard

Department of Oncology, Odense University Hospital:

• Prof PhD MD Per Pfeiffer

Department of Pathology, Odense University Hospital

• Prof PhD MD Sönke Detlefsen

Surgical Department, Karolinska University Hospital, Stockholm

• Prof PhD MD Lars Lundell  
• PhD MD Ioannis Rouvelas
• PhD MD Andrianos Tsekrekos 
• PhD MD Mats Lindblad 
• Prof MD Magnus Nilsson 

Publications associated with the project

Pressurized intraperitoneal aerosol chemotherapy (PIPAC) as an outpatient procedure. Graversen M, Lundell L, Fristrup C, Pfeiffer P, Mortensen MB. Pleura and Peritoneum. 2018-11-27 | DOI: https://doi.org/10.1515/pp-2018-0128.

Prospective, single-center implementation and response evaluation of pressurized intraperitoneal aerosol chemotherapy (PIPAC) for peritoneal metastasis. Graversen M, Detlefsen S, Bjerregaard JK, Fristrup C, Pfeiffer P, Mortensen MB.  Ther Adv Med Oncol 2018 Jun 1;10: 1758835918777036. doi: 10.1177/1758835918777036

Environmental safety during the administration of Pressurized IntraPeritoneal Aerosol Chemotherapy (PIPAC). Graversen M, Pedersen PB, Mortensen MB. Pleura and Peritoneum 2016;1(4):203-8.

Detection of free intraperitoneal tumour cells in peritoneal lavage fluid from patients with peritoneal metastasis before and after treatment with pressurised intraperitoneal aerosol chemotherapy (PIPAC). Graversen M, Fristrup C, Kristensen TK, Larsen TR, Pfeiffer P, Mortensen MB, Detlefsen S. Journal of Clinical Pathology 2019 May;72(5):368-372.