REPEATED TREATMENT WITH HORSE ANTILYMPHOCYTE GLOBULIN FOR SEVERE APLASTIC-ANEMIA

In a single-centre study the feasibility and efficacy of repeated anti lymphocyte globulin (ALG) for patients with severe aplastic anaemia (S AA) not responding to an initial ALG treatment or relapsing after init ial response to ALG was evaluated. 139 consecutive patients with newly diagnosed SAA were treated with ALG between 1976 and 1995. 89 patient s responded to a first course; 50 patients did not become transfusion independent. Of the 89 responders, 66 remained in remission, 23 relaps ed. 43 patients received a second or subsequent course of ALG for fail ure to respond (n = 25) or relapse (n = 18) and were given a total of 53 courses. Acute reactions in the multiply exposed patients occurred during the first ALG treatment in 11 (26%) and during subsequent expos ures in 16/53 courses (30%; P > 0.2). Incidence of serum sickness was 63% (27/43) after the initial course compared to 57% (30/53) after sub sequent courses (P > 0.2), but clinical signs of serum sickness occurr ed earlier after repeated (median 6 d) as compared to initial exposure (13 d; P = 0.008). Transfusion-independent haemopoiesis was achieved in 27/43 (63%) and survival probabilities for the 43 patients receivin g multiple courses of ALG was 52 +/- 8% at 10 years. The probability o f developing a late clonal disorder was 53 +/- 10% after multiple, as compared to 34 +/- 7% after single exposure (P = 0.15). No difference in results was observed between patients retreated for failure to firs t ALG or for relapse. ALG of the same species can be repeated without increased risks of side-effects in patients with SAA. A second or subs equent course of ALG from the same source can be effective when the fi rst course has failed.