CRS-HIPEC in patients with MPM. Secondary objective of this study is to assess safety in patients with peritoneal mesothelioma who are treated with DCBI, which has already been proven in patients with pleural me- sothelioma. Another secondary endpoint of this study is the determination of an immunological response against the tumor as result of the adjuvant therapy. Material and methods: We will conduct an open-label single-center phase II study. The study population will consist of adult patients with a histologically confirmed diagnosis of MPM. A leukapheresis will be per- formed 4 to 6 weeks before CRS-HIPEC. The monocytes collected during leukapheresis will be used for differentiation to dendritic cells (DCs) using specific cytokines. These DCs will be pulsed with PheraLys, a tumor cell lysate derived from 5 well-characterized cell lines from patients with malignant mesothelioma. The tumor lysate-pulsed autologous DCs (MesoPher) are re-injected 8-10 weeks after surgery, 3 times every two weeks. After the third injection with MesoPher, revaccinations to boost the immune system are given after 3 and 6 months. Results: The first patient was included in March 2018. We expect to have enrolled al patients by March 2020. Results are expected in September 2020. Conclusions: The MESOPEC study will determine if administering DBCI in patients with MPM after CRS-HIPEC is feasible and safe. This study could be the first step for new treatment strategies that will show prolonged sur- vival with limited adverse effects in patients with MPM. Conflict of interest: No conflict of interest. 566 CONCOMITANT INTRAPERITONEAL AND SYSTEMIC CHEMOTHERAPY IN PATIENTS WITH EXTENSIVE PERITONEAL CARCINOMATOSIS OF COLORECTAL ORIGIN: CLINICAL TRIAL PROTOCOL OF THE INTERACT TRIAL N. de Boer 1 , A. Brandt 1 , E. van Meerten 2 , R. Mathijssen 2 , E. Madsen 1 , I. de Hingh 3 , C. Verhoef 1 , P. Burger 1 . 1 Erasmus MC Cancer Institute, Department of Surgical Oncology, Rotterdam, Netherlands; 2 Erasmus MC Cancer Institute, Department of Medical Oncology, Rotterdam, Netherlands; 3 Catharina Hospital, Department of Sugical Oncology, Eindhoven, Netherlands Background: Cytoreductive surgery (CRS) and hyperthermic intraperito- neal chemotherapy (HIPEC) has become standard of care for patients with peritoneal carcinomatosis (PC) of colorectal origin with a low/moderate abdominal disease load. In case of a Peritoneal Carcinomatosis Index (PCI) >20, CRS-HIPEC procedure is not considered to be beneficial. Patients who have undergone an open-close procedure are offered palliative/life pro- longing systemic chemotherapy. Previous research shows that systemic chemotherapy is less effective against peritoneal carcinomatosis than it is against hematogeneous spread of colorectal cancer. Several studies sug- gested that in patients with PC, intraperitoneal chemotherapy may be superior to intravenous chemotherapy. The addition of intraperitoneal to systemic chemotherapy in patients with PC of ovarian and gastric origin showed promising results. As of yet, there are no studies investigating intraperitoneal chemotherapy for PC of colorectal origin in this specific patient population. Main objective of this project is to establish the maximum tolerable dose (MTD) and recommended phase II dose of intraperitoneal irinotecan in patients with PC of colorectal origin, added to standard of care systemic chemotherapy. Other endpoints are to explore the safety and feasibility of this treatment and to establish the pharmacokinetic profile of intraperi- toneal administered irinotecan. Material and methods: This study is a classic phase I ‘3+3’ dose-escalation study, which will be conducted in the Erasmus MC, Rotterdam and Catharina Hospital, Eindhoven. Study population will consist of adult pa- tients with PC of colorectal origin and a PCI >20. According to standard work-up for CRS-HIPEC procedure, patients will undergo a planned diag- nostic laparoscopy to score the extent of peritoneal disease. In case of a PCI >20, a peritoneal access port will be implanted at the base of the ribs, the catheter is placed in the abdominal cavity. Through this peritoneal access port we will administer intraperitoneal irinotecan (according to dose- escalation schedule), in combination with standard of care chemotherapy: systemic fluorouracil and oxaliplatin (FOLFOX) and bevacizumab. Results: Start of enrolment is planned for May 2018, and we expect to have enrolled all patients by May 2020. Results are expected in September 2020. Conclusions: The INTERACT trial will determine the MTD, safety and feasibility of intraperitoneal administration of irinotecan, combined with systemic FOLFOX and bevacizumab. This study will also provide pharma- cokinetic data on the intraperitoneal administration of irinotecan. These data are a prerequisite for the safe conduct of future (phase II/III) studies with intraperitoneal irinotecan in patients with PC of colorectal origin, non-eligible for CRS-HIPEC procedure. Conflict of interest: No conflict of interest. 568 SEVERE HEMATOLOGIC TOXICITY FOLLOWING CYTOREDUCTIVE SURGERY COMBINED WITH PERIOPERATIVE INTRAPERITONEAL CHEMOTHERAPY P.A. Torres Mesa 1 , G. Ortega-Perez 2 , O. Alonso-Casado 3 , G. Gui ~ nez 4 , M. Tonello 5 , S. Encinas-Garcia 6 , J. Galipienzo-García 7 , D. Salvatierra-Díaz 7 , M.J. Linero-Noguera 7 , S. Gonz alez-Moreno 3 . 1 MD Anderson Cancer Center Madrid- Spain- GASTROLIFE SAS- Bogota- Colombia, Peritoneal Surface Oncology Program- Department of Surgical Oncology, Bogota, Colombia; 2 MD Anderson Cancer Center Madrid- Spain, Peritoneal Surface Oncology Program- Department of Surgical Oncology, Madrid, Spain; 3 MD Anderson Cancer Center. Madrid- Spain, Peritoneal Surface Oncology Program- Department of Surgical Oncology, Madrid, Spain; 4 MD Anderson Cancer Center. Madrid- Spain- Clinica Alemana- Santiago de Chile- Chile, Peritoneal Surface Oncology Program- Department of Surgical Oncology, Santiago de Chile, Chile; 5 MD Anderson Cancer Center. Madrid- Spain- University of Padua- Padua- Italy, Peritoneal Surface Oncology Program- Department of Surgical Oncology, Padua, Italy; 6 MD Anderson Cancer Center. Madrid- Spain, Department of Medical Oncology, Madrid, Spain; 7 MD Anderson Cancer Center. Madrid- Spain, Department of Anesthesiology, Madrid, Spain Background: Cytoreductive surgery (CRS) combined with Perioperative Intraperitoneal Chemotherapy (PIC) is a curative-intent treatment option for selected patients suffering from a variety of primary or secondary peritoneal surface malignancies. Objective is to describe blood cell kinetics after CRS-PIC. To evaluate severe hematologic toxicity in this context and its association with possible contributing or causal factors Patients and Methods: Retrospective review of a prospectively-main- tained database containing consecutive patients with peritoneal malig- nancies subjected to curative-intent CRS-PIC from 2004 to 2015 in a monographic cancer center. Patients presented a variety of pathological diagnosis. All pertinent clinical, surgical and pathological variables were extracted, including daily blood cell counts in the first 2 weeks after CRS- PIC. Univariate and multivariate analysis were employed to ascertain possible associations of any of the recorded variables with severe hema- tologic toxicity, as defined by the NCI Common Toxicity Criteria. Results: 107 CRS-PIC procedures were performed in 97 patients. PIC mo- dalities employed were: HIPEC alone 89 cases (51 bidirectional); HIPEC followed by EPIC (Early Postoperative Intraperitoneal Chemotherapy) 16 cases; EPIC alone 2 cases. Mitomicina-C (MMC) emerged as an indepen- dent risk factor for severe hematologic toxicity: any bone marrow toxicity (OR3.64, CI95% 1.08-12.2;p¼0.037); Severe neutropenia (OR17.18, CI95% 3.41-86.5;p¼0.001); Thrombocytopenia (OR4.71,CI95% 1.10-20;p¼0.036). Variables related to prior systemic therapy (neutropenia use of GM-CSF, number of cycles or number of treatment lines) iterative procedures, splenectomy, operative time or peritoneal disease burden (measured by the Peritoneal Cancer Index-PCI) were not found to be associated with severe hematologic toxicity. Following CRS and PIC, the nadir values for neutrophils and platelets occurred on the ninth and tenth postoperative days. HIPEC-EPIC comparatively showed a high 33% severe toxicity, resulting in 2 toxic deaths. Conclusion: HIPEC with MMC is an independent risk factor for severe hematologic toxicity (neutropenia and/or thrombocytopenia) in patients subjected to CRS-PIC. A daily blood count should be perfumed during the first 2 postoperative weeks to detect it and tell it apart from surgically- caused hematologic count alterations. The combination of HIPEC and EPIC must be used with utmost caution given its high comparative toxicity. This Abstracts / European Journal of Surgical Oncology 45 (2019) e25ee158 e143