Evidence of cytogenetic and molecular remission by allogeneic cells after immunosuppressive therapy alone

An immunosuppressive but not myeloablative regimen followed by HLA-matched donor mobiliz ed haemo- poietic stem cell transplantation was employed in two high-risk patients. The first patient had refractory anaemia with excess blasts (RAEB) and cytogenetic evidence of translocation 1;3(p36;q21). The second patient had Phila- delphia-negative but p190 BCR-ABL chimaeric gene positive chronic myelogenous leukaemia in accelerated phase (AP- CML). The conditioning regimen consisted of fludarabine (30 mg/m2/d, days 1 – 3) with cyclophosphamide (300 mg/ m2/d, days 1 – 3). Cyclosporine and methotrexate were employed for acute graft-versus-host disease (aGVHD) prophylaxis. In both cases the engraftment of donor cells was demonstrated by cytogenetics and short tandem repeat polymorphisms via PCR. Both patients are alive with normal cytogenetic (RAEB) and molecular (AP-CML) remissions, 100 and 150 d after allografting, respectively. In particular, in the AP-CML patient, the BCR-ABL became undetectable and the BCR-ABL/ABL ratio was <0·0001.