Metronomic Neoadjuvant Capecitabine and Cyclophosphamide in HUGE Pseudomyxoma Peritonei Patients

Mucinous neoplasms are the most common appendiceal tumors, and the most common cause of Pseudomyxoma peritonei (PMP). The term PMP defines a clinical syndrome characterized by progressive accumulation of mucinous material within the abdominal-pelvic cavity, ultimately leading to patient death due to local-regional progression of the disease. The upfront cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) is regarded as standard treatment for PMP.

However, not every PMP patient benefit from upfront CRS and HIPEC. A proportion of patients could be inoperable due to a lack of clinical conditions for clinical deterioration or comorbidites contra-indicating surgery, or an unresectable disease at the diagnosis. Up to 32% of cases could be present the so-called huge PMP (peritoneal cancer index \>28), where the proportion of patients with complete cytoreduction is low of their entire cohort of PMP patients. Moreover, CRS in huge PMPs generally requires very extensive surgical maneuvers such as total gastric or total colon resection. Hence, the patients suffer from a significant impact on postoperative quality of life due to nutritional issues.

Preoperative systemic chemotherapy might be an option for such advanced cases, as it can possibly reduce the tumor burden, allowing less extensive surgery with less visceral resections. Systemic treatment regimens are associated with relevant toxicity and highcosts. Metronomic schedules might be preferred because of their favorable safety profileand antiangiogenic and immunomodulatory properties.

In unresectable or progressive PMP, a single-center prospective uncontrolled trial showed the safety and promising activity results of a continuous metronomic regimen with capecitabine with cyclophosphamide. At a median follow-up of 22.4 months, median progression-free survival was 9.5 months, and the 1-year overall survival rate was 73.7%. Overall, the disease control rate was 87%, and 6 (27%) patients achieved disease control ≥12 months.

On this basis, a phase II, mono-institutional, single arm trial was designed, evaluating neoadjuvant metronomic capecitabine and cyclophosphamide in patients affected by huge Pseudomyxoma peritonei who are potentially candidates to cytoreductive surgery and HIPEC. The goal of the present study is to evaluate the surgical and oncological outcomes of neoadjuvant metronomic approach with oral capecitabine and cyclophosphamide in patients affected by huge PMP.

In details, after the identification of patients affected by PMP, the measurement of peritoneal cancer index will be assessed by chest and abdominal CT scan at the staging phase. Only patients with PCI\>28 will be recruited regardless of resectability. Once enrolled, the patients will receive staging laparoscopy in order to confirm the histological diagnosis, to accurately stage the disease with the surgical PCI, to be compared with the radiological PCI for accuracy evaluation, and to collect material for the translational analyses. Then the patients will receive a continuous treatment schedule of oral metronomic chemotherapy with capecitabine 1250 mg/m2/day (625 mg/m2 BID) continuously with cyclophosphamide 50 mg/day continuously, for a total of 6 four-weekly cycles. At the completion of the cycles, the patients will be restaged and, as long as they are considered operable, they will be submitted to standard of care cytoreductive surgery/HIPEC, in order to define the reaching of the primary endpoint of completeness of cytoreduction. A total number of 31 patients are planned to be included in the study according to the statistical design.

• Radiological objective tumor response rate. [Срок оценки: Performed at baseline and 16 weeks from the start of treatment.]
• Conversion rate [Срок оценки: 6-8 months from the start of treatment]
• Downsizing of the tumor measured by surgical Peritoneal Cancer index (PCI). [Срок оценки: Performed after 16 weeks.]
• Safety and tolerability of neoadjuvant metronomic chemotherapy. [Срок оценки: 6-8 months.]
• Major complications (NCI-CTCAE v5) associated with CRS and HIPEC [Срок оценки: 30 days after surgery.]
• Quality of life EQ-5D-5L [Срок оценки: Before/after neoadjuvant metronomic chemotherapy, and 30 days after the surgery.]
• Progression-free survival [Срок оценки: After 24 months.]
• Overall Survival. [Срок оценки: After 48 months.]
• Quality of life EORTC-QLQ-C30 [Срок оценки: Within 30 days after the date of surgery.]