Detection of tumor-derived cell-free DNA from colorectal cancer peritoneal metastases in plasma and peritoneal fluid.

Tumor-derived cell-free DNA (cfDNA) is an emerging biomarker for guiding the personalized treatment of patients with metastatic colorectal cancer (CRC). While patients with CRC liver metastases (CRC-LM) have relatively high levels of plasma cfDNA, little is known about patients with CRC peritoneal metastases (CRC-PM). This study evaluated the presence of tumor-derived cfDNA in plasma and peritoneal fluid (i.e. ascites or peritoneal washing) in 20 patients with isolated CRC-PM and in the plasma of 100 patients with isolated CRC-LM. Among tumor tissue KRAS/BRAF mutation carriers, tumor-derived cfDNA was detected by droplet digital polymerase chain reaction (ddPCR) in plasma of 93% of CRC-LM and 20% of CRC-PM patients and in peritoneal fluid in all CRC-PM patients. Mutant allele fraction (MAF) and mutant copies per ml (MTc/ml) were lower in CRC-PM plasma than in CRC-LM plasma (median MAF = 0.28 versus 18.9%, p < 0.0001; median MTc/ml = 21 versus 1,758, p < 0.0001). Within patients with CRC-PM, higher cfDNA levels were observed in peritoneal fluid than in plasma (median MAF = 16.4 versus 0.28%, p = 0.0019; median MTc/ml = 305 versus 21, p = 0.0034). These data imply that tumor-derived cfDNA in plasma is a poor biomarker to monitor CRC-PM. Instead, cfDNA detection in peritoneal fluid may offer an alternative to guide CRC-PM treatment decisions.

Treatment of Peritoneal Dissemination in Stomach Cancer Patients With Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy (HIPEC): Rationale and Design of the PERISCOPE Study.

BACKGROUND: Patients with gastric cancer and peritoneal carcinomatosis have a very poor prognosis; median survival is 3 to 4 months. Palliative systemic chemotherapy is currently the only treatment available in the Netherlands. Intraoperative hyperthermic intraperitoneal chemotherapy (HIPEC) has an established role in the treatment of peritoneal carcinomatosis originating from colorectal cancer, appendiceal cancer, and pseudomyxoma peritonei; its role in gastric cancer is uncertain. Currently, there is no consensus on the choice of chemotherapeutic agents used in HIPEC for gastric cancer. OBJECTIVE: The main objectives of this study are (1) to investigate the safety, tolerability, and feasibility of gastrectomy combined with cytoreductive surgery and HIPEC after systemic chemotherapy, as a primary treatment option for patients with advanced gastric cancer with tumor positive peritoneal cytology and/or limited peritoneal carcinomatosis; and (2) to determine the maximum tolerated dose (MTD) of intraperitoneal docetaxel in combination with a fixed dose of intraperitoneal oxaliplatin. METHODS: The PERISCOPE study is a multicenter, open label, phase I-II dose-escalation study. The MTD of docetaxel will be studied using a 3+3 design. Patients with locally advanced (cT3-cT4) gastric adenocarcinoma are eligible for inclusion if the primary gastric tumor is considered resectable, tumor positive peritoneal cytology and/or limited peritoneal carcinomatosis is confirmed by diagnostic laparoscopy/ laparotomy, and prior systemic chemotherapy was without disease progression. At laparotomy, cytoreductive surgery (complete removal of all macroscopically visible tumor deposits) and a total or partial gastrectomy with a D2 lymph node dissection is performed. An open HIPEC technique is used with 460mg/m2 hyperthermic oxaliplatin for 30 minutes (41°C to 42°C) followed by normothermic docetaxel for 90 minutes (37°C) in a dose that will be escalated per 3 patients (0, 50, 75, 100, 125, 150 mg/m2). The primary endpoint is treatment related toxicity. RESULTS: Patient accrual is ongoing and the first results are expected in 2017. CONCLUSIONS: The PERISCOPE study will determine the safety, tolerability, and feasibility of gastrectomy combined with cytoreduction and HIPEC using oxaliplatin in combination with docetaxel after systemic chemotherapy as primary treatment option for gastric cancer patients with tumor positive peritoneal cytology and/or limited peritoneal carcinomatosis. This study will provide pharmacokinetic data on the intraperitoneal administration of oxaliplatin and docetaxel, including the MTD of intraperitoneal-administered docetaxel. These data are a prerequisite for the safe conduct of future HIPEC studies in patients with gastric cancer. TRIAL REGISTRATION: Netherlands Trial Registration (NTR): NTR4250; http://www.trialregister.nl/trialreg/admin/ rctview.asp?TC=4250 (Archived by WebCite at http://www.webcitation.org/6rWJONgkt).