Aplastic anemia treated by allogeneic bone marrow transplantation: a report on 49 new cases from Seattle

Forty nine patients with severe aplastic anemia, 33 due to unknown cause, 11 drug or chemical related, 2 associated with hepatitis, 1 with paroxysmal nocturnal hemoglobinuria, and 2 possibly associated with Fanconi syndrome did not show recovery after 0.5 to 96 (median 2) mo of conventional therapy. Twenty two were infected and 21 were refractory to random platelet transfusions at the time of admission. All were given marrow grafts from HLA identical siblings. Forty five were conditioned for grafting by cyclophosphamide (CY), 50 mg/kg on each of 4 successive days, and 4 by 1000 rad total body irradiation. All were given intermittent methotrexate therapy within the first 100 days of grafting to modify graft versus host disease (GVHD). Three patients died from infection too early to evaluate (days 1-8). Forty six had marrow engraftment. Of these, 20 are surviving with good peripheral blood counts between 186 and 999 days, and 18 have returned to normal activities. Chronic GVHD is a problem in five. Twelve patients died of infection following rejection of the marrow graft. Twelve patients died with bacterial or fungal infections or interstitial pneumonia and active GVHD or soon following resolution of GVHD. Two patients died with marrow engraftment and no GVHD, one with an interstitial, and the other with a bacterial pneumonia. Thirty six patients who had received random donor blood transfusions were randomly assigned to receive either CY or procarbazine antithymocyte globulin CY as conditioning regimens to test whether the incidence of graft rejection could be decreased. There was no difference in the incidence of graft rejection between the two regimens. In 13 patients with rejection, second transplants were attempted either with the original marrow donor (9 patients) or another HLA identical sibling (4 patients). Three of these transplants were not evaluable, seven were unsuccessful and three were successful with only one of the three surviving for more than 468 days. In conclusion, the long term survivial of 41% of the patients in the present study is similar to that achieved in our first 24 patients, and confirms the importance of marrow transplantation for the treatment of severe aplastic anemia. Marrow graft rejection, GVHD, and infections continue to be the major causes of failure.