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 × 10⁹/l (odds ratio 5·19, P = 0·0011) were independent predictors of response to treatment. Stratification according to PNH positivity and ARC ≥30 × 10⁹/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.