PB0363 - A case report of quinine-induced thrombotic microangiopathy treated with eculizumab

Background: Immune-mediated drug-induced thrombotic microangiopathy (DITMA) results from drug-dependent antibodies that react with different cells including platelets, endothelial cells, and neutrophils. This leads to microvascular thrombosis and thrombocytopenia. The most common cause of immune-mediated DITMA is quinine, an antimalarial drug also found in tonic water. Quinine-induced TMA commonly results in acute kidney injury and chronic kidney disease. The diagnosis may be challenging as quinine consumption may not be recognised. Quinine-dependent antibodies are commonly identifiable and can confirm the diagnosis.

The optimal treatment for quinine-induced TMA is not known. Eculizumab, a monoclonal antibody against complement C5, has demonstrated success in various DITMA (e.g., carfilzomib, gemcitabine) but its use in quinine-induced TMA has not been reported to date.

Aims: we discuss a case of quinine-induced TMA successfully treated with eculizumab (off-label)

Methods: a case report

Results: A 55-years-old female presented with 4 days of back pain, dark urine, agitation, and diarrhea within 24 hours of consuming quinine for cramps. Blood tests on presentation are presented in Table 1. Notably, she had abnormal liver function studies and markedly elevated ferritin which is not typical of thrombotic thrombocytopenic purpura or complement-mediated TMA.

She received 2 sessions of plasmapheresis on suspicion of TMA. This was ceased upon elucidating the history of quinine exposure. She received a dose of methylprednisolone and commenced on eculizumab treatment for 6 months (900 mg every week for four weeks followed by 1200 mg every two weeks). Her thrombocytopenia and anemia resolved by 1 and 6 weeks, respectively. She required hemodialysis for a month and gained full recovery of renal function. A strongly positive quinine-dependent platelet-associated antibody was subsequently reported.

Conclusion(s): This is the first reported case of quinine-induced TMA successfully treated with eculizumab to our knowledge. We recommend further studies to assess the efficacy of complement inhibition in quinine and other DITMA.