Stage IV Pancreatic Cancer Patient Treated With FOLFIRINOX Combined With Oral Methioninase: A Highly-Rare Case With Long-term Stable Disease

Abstract

Background: Pancreatic cancer is one of the most recalcitrant cancers, and more effective therapy is needed. Pre-clinical studies have shown that patient-derived orthotopic xenograft (PDOX) mouse models of pancreatic cancer are effectively treated with oral recombinant methioninase (o-rMETase). Case Report: A 62-year-old woman diagnosed with stage IV pancreatic cancer was treated with the combination of 5-fluorouracil/leucovorin, irinotecan, and oxaliplatinum (FOLFIRINOX) every two weeks and o-rMETase twice a day as a supplement. The patient was also on a low-methionine diet. Disease progression was monitored by CA19-9 and computed tomography. The patient initially responded to FOLFIRINOX, shown by a great reduction in CA19-9 levels, with tumor shrinkage shown by computed tomography. The patient began taking o-rMETase and went on a low-methionine diet one year after diagnosis which she has maintained without side effects for 7 months. The patient's CA19-9 level and tumor size remain stable 19 months after diagnosis. The patient is alive and has maintained a high performance status. Historical data show that less than 5% of stage IV pancreatic-cancer patients on FOLFIRINOX have stable disease 1.5 years after diagnosis. Conclusion: The combination of o-rMETase and FOLFIRINOX may be synergistic in stage IV pancreatic cancer. Pancreatic cancer is the 3 rd leading cause of cancer-related death in the United States and 4 th in Japan (1, 2). Pancreatic cancer often progresses without symptoms, and most patients are not indicated for surgery because of tumor invasion of adjacent organs or distant metastases. Chemotherapy for advanced cases currently comprises FOLFIRINOX [5-fluorouracil (5-FU)/leucovorin, irinotecan, and oxaliplatinum] or gemcitabine (GEM) + nab-paclitaxel as first-line standard of care.

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