Allogeneic stem cell transplantation in paroxysmal nocturnal hemoglobinuria

In the era of eculizumab, identifying patients with paroxysmal nocturnal hemoglobinuria who may benefit from allogeneic stem cell transplantation is challenging.

We describe the characteristics and overall survival of 211 patients transplanted for paroxysmal nocturnal hemoglobinuria in 83 EBMT centers from 1978 to 2007. Next, we conducted a comparison with a cohort of 402 non-transplanted patients with paroxysmal nocturnal hemoglobinuria diagnosed between 1950 and 2005 in 92 French centers. We compared the occurrence of complications (i.e. thromboembolism and aplastic anemia) using either an individual or a stratum-matching procedure.

After a median follow-up of 5 years, the 5-year overall survival rate ± standard error (%) was 68 ± 3 in the transplanted group (54 ± 7 in the case of thromboembolism, 69 ± 5 in the case of aplastic anemia without thromboembolism and 86 ± 6 in the case of recurrent hemolytic anemia without thromboembolism or aplastic anemia). Only thromboembolism as the indication for transplantation was associated with worse outcome (P=0.03). We identified 24 pairs of transplanted and non-transplanted patients with thromboembolism for the matched comparison, with worse overall survival for the transplanted patients (hazard ratio=10.0; 95% confidence interval, 1.3-78.1; P=0.007). This was confirmed by the global matching procedure (P=0.03). As regards aplastic anemia without thromboembolism, 30 pairs were identified for the matched comparison. It was not observed that transplanted patients had a significantly worse overall survival (hazard ratio=4.0; 95% confidence interval, 0.9-18.9; P=0.06). A global matching procedure was not feasible.

Allogeneic stem cell transplantation is probably not a suitable treatment option for life-threatening thromboembolism in paroxysmal nocturnal hemoglobinuria.