Anti-PD1-/PDL1-induced chronic intestinal pseudo-obstruction: three cases treated with vedolizumab after corticosteroid failure with mixed results.

Immune checkpoint inhibitors (ICI), i.e., anti-PD1/PDL1 and anti-CTLA-4, have reshaped the prognosis of many cancers. Increased use of ICI has led to the onset of new adverse events. Neurological immune-related adverse events are rare, heterogenous, and potentially life-threatening. Chronic intestinal pseudo-obstruction (CIPO) is an immune-related autonomic plexus neuropathy that may be caused by infiltration of the myenteric plexus by CD8 + T cells. It is a rare and potentially fatal side effect that can be difficult to diagnose early because of initial nonspecific clinical presentation including vomiting, nausea, diarrhea, and constipation. Some rare cases have been described in the literature reporting a frequent resistance to corticosteroids making it necessary to use other immunosuppressive therapy. Vedolizumab is an antibody (Ab) blocking integrin α4-β7 used to treat inflammatory bowel disease. We report the first three cases of ICI-induced CIPO-treated with vedolizumab after corticosteroid failure, with very limited benefits (only one patient with transitory improvement). Based on our results in three cases, vedolizumab does not currently appear to be a therapeutic option. Earlier administration with a standardized dose and frequency schedule may provide better outcomes.