Unexpected adverse event caused by avacopan: a case of drug-induced hypersensitivity syndrome in microscopic...

Area of Science:

• Nephrology
• Rheumatology
• Immunology

Background:

• Microscopic polyangiitis (MPA) is a small vessel vasculitis associated with antineutrophil cytoplasmic antibodies.
• Avacopan, a C5a receptor inhibitor, offers an alternative treatment for MPA, reducing glucocorticoid dependence.
• Liver injury is a known adverse effect of avacopan, but drug-induced hypersensitivity syndrome (DIHS) is rare.

Purpose of the Study:

• To report a rare case of drug-induced hypersensitivity syndrome (DIHS) and severe liver dysfunction in a patient with microscopic polyangiitis (MPA) treated with avacopan.
• To emphasize the importance of monitoring for delayed adverse events during avacopan therapy.

Main Methods:

• Case report of a 77-year-old woman with MPA treated with prednisolone and avacopan.
• Clinical monitoring for disease activity, liver function, and adverse events.
• Diagnostic workup including laboratory tests and liver biopsy.
• Analysis of adverse events following avacopan initiation.

Main Results:

• The patient achieved MPA remission but developed significant liver dysfunction 7 weeks after starting avacopan.
• She subsequently presented with fever and rash, diagnosed as DIHS with human herpesvirus 6 reactivation.
• Liver biopsy confirmed drug-induced hepatitis, requiring prolonged hospitalization despite avacopan discontinuation.

Conclusions:

• Avacopan can lead to rare but serious adverse events like DIHS and drug-induced hepatitis in MPA patients.
• Delayed monitoring for severe skin symptoms is essential during avacopan treatment.
• This case underscores the need for vigilance regarding avacopan's potential toxicities.