Prognostic value of hematopoietic chimerism in patients with acute leukemia after allogeneic bone marrow transplantation: a prospective study

Hematopoietic chimerism as a predictive marker for the relapse of acute leu kemia after allogeneic BMT was evaluated in a prospective study. Monthly as says of hematopoietic chimerism were performed from peripheral blood sample s by PCR amplification of short tandem repeats or amelogenin loci. Between December 1997 and June 1999, 33 patients enrolled and 30 were evaluable (tw o early deaths, one lack of informative bands for chimerism evaluation). Th ere were 14 male and 16 female patients (15 AML and 15 ALL) with a median a ge of 31 years (range 16-46). Mixed chimerism (MC) was observed at least on ce in 14 of 30 patients (47%). There was no significant difference between 14 patients who showed MC (MC group) and 16 patients who did not show MC (c omplete chimerism (CC) group) in terms of age, sex, disease status at BMT, donor type, and the number of bone marrow cells infused. There was no signi ficant difference in the neutrophil and platelet engraftment rates between the two groups. After a median follow up of 10.9 months (range 4.3-22.4), f ive patients in the CC group and two patients in the MC group relapsed (P = 0.27), All five patients who relapsed in the CC group maintained CC up to 1 month prior to clinical relapse. Our study demonstrated that the patients who showed MC post BMT did not have higher risk of relapse of acute leukem ia when compared to patients who did not show MC. Sensitive PCR-based assay s for hematopoietic chimerism applied on a monthly basis after allogeneic B MT could not predict relapse of acute leukemia.