Paroxysmal nocturnal haemoglobinuria – survival benefit with eculizumab

Treatment of paroxysmal nocturnal haemoglobinuria (PNH) with eculizumab under Australia’s Life Saving Drugs Program has led to a significant reduction in deaths compared to best supportive care.

A retrospective study comparing 68 Australian patients treated with eculizumab and 230 patients in the International PNH Registry who were eligible but never treated with eculizumab has confirmed the survival benefit from the monoclonal antibody.

The study, presented at Blood 2021 by Professor Jeff Szer, found a history of thromboembolism was more common at baseline in the eculizumab treated group than in the never treated patients (34.8% v 12.2%).

The other main difference at baseline was more coexisting bone marrow failure syndrome in untreated patients (3% v 13.2%) which Professor Szer said may be related to geographical diversity.

Both groups looked similar prior to baseline in terms of symptoms such as dysphagia, fatigue, headaches, dyspnoea and erectile dysfunction.

However he said the symptoms of abdominal pain and haemoglobinuria were possibly higher in the treated group, perhaps reflecting the severity of the disease in this group.

Professor Szer, from the Peter MacCallum Cancer Centre, said baseline laboratory values were largely similar.

“All patients had a Hb in the anaemic range with evidence of intravascular haemolysis by virtue of the very low haptoglobin levels.”

There was mild thrombocytopenia in both groups while serum creatinine and EGFR were generally in the normal range of most patients.

A history of transfusions in the 12 months before baseline was more common in eculizumab treated group however the untreated group had more than twice as many transfusions as the treated group in the 6 months prior to the last follow-up.

Professor Szer said survival of the never treated patient group at 8 years was in the range of what one might expect from historical series.

“The Australian treated cohort has a much improved survival with only two events seen during this 8-year period.”

The 8-yr survival for the eculizumab treated group was 96.1% as compared to 75% in the best supportive care cohort of.

“This corresponds to an 82% reduction in deaths with a HR of 0.18,” he said.

“We can therefore conclude that eculizumab, as provided to Australian PNH patients under the Life Saving Drugs Program has resulted in a significant improvement in survival for these patients.”

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