Cytotoxic immunosuppressive drug treatment strategy in pure red cell aplasia.

Remissions occurred in 2 of 5 consecutive cases of acquired pure red cell aplasia (PRCA) during an initial course of treatment with either azathioprine and prednisolone, or cyclophosphamide and prednisolone. Crossover to therapy with the alternative cytotoxic immunosuppressive agent in conjunction with continued administration of prednisolone in 3 unresponsive cases resulted in remission induction. Crossover to azathioprine was effective in 2 cases initially unresponsive to cyclophosphamide, and crossover to cyclophosphamide in 1 initially unresponsive to azathioprine. This emphasises that lack of cross-resistance to these drugs can occur in PRCA, and that crossover to treatment with the alternative agent in refractory cases is a useful strategy which has been underutilised in reported approaches to management. Administration of the effective regimen was continued for a mean of 15 months, and this more extended period of treatment was associated with a longer mean duration of remission than reported in previous studies.