Management of Immune-Related Gastrointestinal Adverse Events in Cancer Patients

Introduction to Pembrolizumab-Associated Gastrointestinal Toxicity

• The primary risk is that pantoprazole may mask early gastrointestinal symptoms of immune-related adverse events (irAEs), particularly immune-mediated colitis, in patients receiving pembrolizumab therapy, according to the National Comprehensive Cancer Network 1, 2
• Pembrolizumab commonly causes diarrhea, which could be mistaken for acid-related symptoms or overlooked while on acid suppression, as reported by the Journal of the National Comprehensive Cancer Network 2, 3, 1

Common GI Adverse Events and Immune-Mediated Colitis

• Diarrhea, nausea, decreased appetite, and constipation are among the most common adverse events with pembrolizumab, as stated by the Journal of the National Comprehensive Cancer Network 2, 3, 1
• Immune-mediated colitis occurs as a serious irAE and can present with diarrhea, abdominal pain, and bloody stools, according to the Journal of the National Comprehensive Cancer Network 2, 3, 1
• Colitis typically develops within the first 2 cycles of therapy but can occur at any time during treatment, as noted by Praxis Medical Insights 4

Severity and Management of Immune-Mediated Colitis

• Fatal outcomes have been reported with delayed recognition and treatment of immune-mediated colitis, highlighting the importance of prompt intervention, as reported by Cancer Treatment Reviews 5
• The American Society of Clinical Oncology recommends monitoring for new-onset diarrhea, abdominal pain, blood in stool, or mucus in stool, and assessing GI symptoms at each pembrolizumab infusion visit, as stated by Praxis Medical Insights 4

Combination Therapy Context and Implications for Monitoring

• When pembrolizumab is combined with chemotherapy, diarrhea incidence increases, and grade ≥3 diarrhea risk also increases, as reported by Cancer Treatment Reviews 5
• Elevated liver enzymes, nausea, and vomiting are more frequent with combination regimens, and pneumonitis risk significantly increases with chemotherapy combinations, according to Cancer Treatment Reviews 5
• More frequent assessment of GI symptoms is warranted with combination regimens, and a lower threshold for intervention is recommended given higher baseline toxicity rates, as stated by Cancer Treatment Reviews 5