Oral Budesonide in Oncology: A Novel Approach to Managing Gastrointestinal Immune-Related Adverse Events

Budesonide is a potent topical glucocorticosteroid with limited systemic activity owing to its extensive hepatic first-pass metabolism following oral administration. Its efficacy and safety have been well-established in gastroenterology, particularly for inducing and maintaining remission in patients with inflammatory bowel diseases: mild-to-moderate ulcerative colitis, Crohn's disease and microscopic colitis. However, the potential role of oral budesonide in oncology has only recently been recognized, particularly for managing various types of gastrointestinal immune-related adverse events, which are among the most common toxicities observed in cancer patients treated with immune checkpoint inhibitors. Potential applications of oral budesonide in this context include the treatment of immunotherapy-induced microscopic and non-microscopic colitis, enteritis, upper gastrointestinal involvement, and, to a lesser extent, hepatitis. In these cases, oral budesonide may serve as a primary treatment to induce remission, replacing systemic steroids, or as a bridging therapy transitioning from systemic steroids, facilitating a quicker resumption of immunotherapy following its temporary discontinuation due to toxicity. Oral budesonide represents a particularly attractive treatment option in oncology due to its minimal systemic activity, low risk of steroid-related side effects, and very limited potential to cause immune suppression — offering a marked contrast to systemic steroids. In this article, we summarize the current evidence on the potential applications of oral budesonide in oncology, highlighting its promise as a targeted and well-tolerated treatment option for managing gastrointestinal immune-related toxicities that preserves the anti-cancer efficacy of immunotherapy.