Bortezomib-induced paralytic ileus is a potential gastrointestinal side effect of this first-in-class anticancer proteasome inhibitor

Bortezomib is the first anticancer proteasome inhibitor introduced into clinical practice. It has been recently approved for the treatment of multiple myeloma, an incurable plasma cell tumour that accounts for 10-15% of all haematologic malignancies and for approximately 20% of deaths. Gastrointestinal toxicity associated with the use of this drug is common but generally mild to moderate. Paralytic ileus in patients undergoing bortezomib treatment has been reported, although a definite attribution to bortezomib administration has not been established. We report a myeloma patient who developed severe paralytic ileus during bortezomib therapy, which presented in the context of progressive constipation without other known causes and which regressed promptly with medical management after drug cessation, suggesting a direct causal relationship. Awareness of the various potential gastrointestinal toxic effects of bortezomib is of relevance given the growing number of patients undergoing treatment with this important and effective new cancer drug.