Predictive Value of FDG Uptake on PET for Future Immune Checkpoint Inhibitor-Mediated Colitis: A Case Series

Area of Science:

• Oncology
• Immunology
• Radiology

Background:

• Immune-mediated colitis (IMC) is a frequent immune-related adverse event associated with immune checkpoint inhibitor (ICI) therapy.
• Early detection and management of IMC are crucial for patient outcomes.

Purpose of the Study:

• To investigate the utility of PET/CT scans in predicting imminent IMC during ICI therapy.
• To highlight atypical presentations of IMC.

Main Methods:

• Retrospective review of 33 adult patients receiving ICIs who underwent PET/CT surveillance.
• Analysis of PET/CT scans obtained 2-6 weeks before and up to 3 months after colitis diagnosis.
• Correlation of imaging findings with clinical colitis presentation and outcomes.

Main Results:

• Most patients (72.7%) had negative PET/CT findings for colitis.
• No significant difference in diarrhea or colitis severity between PET/CT positive and negative groups.
• Similar colitis resolution rates (81.8% negative vs. 71.4% positive PET/CT).

Conclusions:

• PET/CT imaging did not effectively predict IMC in this cohort.
• The time interval between clinical IMC onset and surveillance imaging may limit predictive value.
• Clinical criteria, laboratory markers (lactoferrin, calprotectin), and endoscopy/histology are vital for accurate IMC detection.