Hepatitis B Virus Reactivation During FOLFIRINOX Chemotherapy and Granulocyte Colony-Stimulating Factor in Advanced Pancreatic Cancer Case Report

Abstract Hepatitis B reactivation is a well-recognized complication of immunosuppressive therapy, most commonly reported in patients with hematologic malignancies receiving potent regimens. In contrast, reports of reactivation occur less commonly in solid malignancies, especially pancreatic cancer. Data are limited regarding the potential impact of multidrug therapies, such as FOLFIRINOX. Granulocyte colony-stimulating factor (G-CSF) is frequently used adjunctively, but its role in HBV reactivation is unknown. We report a case of hepatitis B reactivation in a patient with advanced pancreatic cancer with metastasis to the liver receiving modified FOLFIRINOX and pegfilgrastim. The patient presented on June 2, 2025, with fatigue, weakness, peripheral edema, and leukocytosis after cycle 2 of modified FOLFIRINOX on May 21 and pegfilgrastim on May 23. FOLFIRINOX was held during admission because of poor tolerance. Liver enzymes rose during hospitalization, and hepatitis testing demonstrated reactive HBsAg and total anti-HBc, nonreactive anti-HBc IgM, anti-HBs <5 mIU/mL, and HBV DNA 3,760,000 IU/mL (log 6.58). Review of prior records demonstrated HBsAg positivity and negative anti-HBc IgM before chemotherapy, but baseline HBV DNA was not obtained and antiviral prophylaxis was not documented. He was discharged on June 7 and was subsequently started on entecavir 0.5 mg daily by outpatient oncology on June 18. Current guidelines recommend HBV screening before systemic anticancer therapy and antiviral prophylaxis for HBsAg-positive patients receiving systemic therapy. Thus, this case highlights the importance of implementing existing recommendations for complete HBV screening, baseline HBV DNA assessment, and antiviral prophylaxis in patients with solid tumors receiving chemotherapy.