INDUCTION OF MOLECULAR REMISSION BY DONOR PERIPHERAL-BLOOD LEUKOCYTE THERAPY IN PATIENTS RELAPSING WITH EXTRAMEDULLARY BLASTIC PHASE CHRONIC MYELOID-LEUKEMIA AFTER ALLOGENEIC BONE-MARROW TRANSPLANTATION

Two patients with chronic myeloid leukemia (CML) who relapsed in blast ic transformation after allogeneic bone marrow transplantation (BMT) w ere treated with infusions of leukapheresed peripheral blood mononucle ar cells from their original donor. At relapse, their disease was char acterized by symptomatic extramedullary deposits of leukemia with mini mal (PCR positive, cytologically negative) involvement of bone marrow. Treatment with donor cell infusions was associated with clinical remi ssion, return of full donor chimerism and loss of the BCR-ABL transcri pt detectable in bone marrow before donor leukocyte infusion (molecula r remission). Donor leukocyte infusions should be considered for thera py of relapsed blastic phase CML after allogeneic BMT, especially when the relapse is primarily extramedullary and responsive to local and s ystemic cytoreductive therapy. However, severe GVHD and CNS relapse re main obstacles to achieving a successful long-term outcome.