Mytomicin-C, Metronomic Capecitabine, and Bevacizumab in Patients With Unresectable or Relapsed Pseudomyxoma Peritonei of Appendiceal Origin

Introduction: Pseudomyxoma peritonei (PMP) is a rare, slow growing tumor, traditionally considered chemoresistant. The only curative approach is cytoreductive surgery (CRS) followed by hyperthermic intraperitoneal chemotherapy (HIPEC). At disease relapse, or in patients with inoperable disease at diagnosis, no standard treatment has been defined, though nonrandomized series showed promising results with fluoropyrimidine-based regimens.

Patients and methods: We conducted a prospective study in patients with relapsed or unresectable PMP and confirmed disease progression at baseline. Patients received MMC (7 mg/m² every 6 weeks, up to a maximum of 4 cycles) plus metronomic capecitabine (625 mg/sqm/day b.i.d.) and bevacizumab (7.5 mg/kg every 3 weeks) until disease progression, unacceptable toxicity, or consent withdrawal. Primary endpoint was progression-free survival (PFS); secondary endpoints were overall survival (OS), overall response rate according to RECIST v1.1 criteria, serum markers response and safety.

Results: Fifteen patients were included. At a median follow-up of 26.1 months (IQR, 17.7-49.6), median PFS was 17.9 months (95% CI, 11.0-NE), with 1-year PFS and OS rates of 73% and 87%. Safety profile was manageable, with only 13% G3/G4 treatment-related adverse events.

Conclusion: Metronomic capecitabine, bevacizumab, and MMC are an active regimen in advanced and progressive PMP and favorably compares with historical series.