Prognostic value of paroxysmal nocturnal haemoglobinuria clone presence in aplastic anaemia patients treated with combined immunosuppression: results of two-centre prospective study.

Paroxysmal nocturnal haemoglobinuria (PNH) clones are frequently detected in patients with aplastic anaemia (AA). To evaluate the prognostic role of PNH clone presence we conducted a prospective study in 125 AA patients treated with combined immunosuppressive therapy (IST). Seventy-four patients (59%) had a PNH clone (PNH+ patients) at diagnosis, with a median clone size of 0·60% in granulocytes and 0·15% in red blood cells. The response rate at 6 months was higher in PNH+ patients than that in PNH- patients, both after first- and second-line IST: 68% vs. 45%, P = 0·0164 and 53% vs. 13%, P = 0·0502 respectively. Moreover, 42% of PNH+ patients achieved complete remission compared with only 16% of PNH- patients (P = 0·0029). In multivariate logistic regression analysis, PNH clone presence (odds ratio 2·56, P = 0·0180) and baseline absolute reticulocyte count (ARC) ≥30 × 10(9) /l (odds ratio 5·19, P = 0·0011) were independent predictors of response to treatment. Stratification according to PNH positivity and ARC ≥30 × 10(9) /l showed significant distinctions for cumulative incidence of response, overall and failure-free survival. The results of this prospective study confirmed the favourable prognostic value of PNH clone presence in the setting of IST for AA.