Infusions of large numbers (> 10(8)/kg) of donor leukocytes can induce remissions in patients with chronic myeloid leukemia (CML) who relapse after marrow transplantation. We wanted to determine if substantially lower numbers of donor leukocytes could induce remissions and, if so, whether this would reduce the 90% incidence of graft-versus-host disease (GVHD) associated with this therapy. Twenty-two patients with relapsed CML were studied: 2 in molecular relapse, 6 in cytogenetic relapse, 10 in chronic phase, and 4 in accelerated phase. Each patient received escalating doses of donor leukocytes at 4- to 33-week intervals. Leukocyte doses were calculated as T cells per kilogram of recipient weight. There were 8 dose levels between 1 x 10(5) and 5 x 10(8). Lineage-specific chimerism and residual leukemia detection were assessed using sensitive polymerase chain reaction (PCR) methodologies. Nineteen of the 22 patients achieved remission. Remissions were achieved at the following T-cell doses: 1 x 10(7) (n = 8), 5 x 10(7) (n = 4), 1 x 10(8) (n = 3), and 5 x 10(8) (n = 4). To date, 15 of the 17 evaluable patients have become BCR-ABL negative by PCR. The incidence of GVHD was correlated with the dose of T cells administered. Only 1 of the 8 patients who achieved remission at a T-cell dose of 1 x 10(7)/kg developed GVHD, whereas this complication developed in 8 of the 11 responders who received a T-cell dose of > or = 5 x 10(7)/kg. Three patients died in remission, 1 secondary to marrow aplasia, 1 of respiratory failure and 1 of complications of chronic GVHD. Sixteen patients who were mixed T-cell chimeras before treatment became full donor T-cell chimeras at the time of remission. Donor leukocytes with a T-cell content as low as 1 x 10(7)/kg can result in complete donor chimerism together with a potent graft-versus-leukemia (GVL) effect. The dose of donor leukocytes or T cells used may be important in determining both the GVL response and the incidence of GVHD. In many patients, this potent GVL effect can occur in the absence of clinical GVHD.

We prospectively evaluated the efficacy of T-cell-depleted bone marrow transplantation (BMT) in adults with de novo acute nonlymphocytic leukemia (ANLL) in first complete remission (CR), with regard to relapse-free survival and incidence of graft-versus-host disease (GvHD). Thirty-one patients older than 16 years (range, 16.5 to 43.2) received T-cell-depleted grafts for this purpose from related HLA/MLC- compatible donors. Twelve of the patients were older than 30 years at the time of transplantation. Patients were prepared with hyperfractionated total body irradiation (HFTBI; 1,375 to 1,500 cGy) and high-dose cyclophosphamide (120 mg/kg). T cells were removed from the marrow grafts by a two-step soybean lectin agglutination and sheep red blood cell (sRBC)-rosette procedure, achieving a 2.5- to 3-log depletion of clonable T lymphocytes. No additional prophylaxis against GvHD was administered. The median age at transplantation was 28.8 years; the median interval from diagnosis to transplantation was 3.8 months, and from CR was 2.7 months. Seventy-four percent received consolidation after remission induction therapy. The product-limit estimate of disease-free survival (DFS) at 3 years is 45% (95% confidence interval [CI], 24% to 66%), and the cause-specific probability of relapse is 13%. The median follow-up of the survivors is 72 months (range, 34.5 to 95.6). Median time to achieve a sustained absolute neutrophil count of 500 or greater was 16 days, and to maintain an untransfused platelet count of 20,000 or greater was 20 days. Five patients suffered immune-mediated graft rejection. Three patients developed grade I to II acute GvHD limited to the skin, which resolved promptly with brief courses of systemic steroids. None of the patients has developed clinically apparent chronic GvHD or a secondary lymphoproliferative disorder, and no patient is receiving immunosuppressive therapy. T-cell-depleted BMT by the method reported here is a favorable option as postremission therapy for adults with de novo ANLL in first remission who have an HLA/MLC-compatible related donor, and it is not associated with an increased risk of relapse posttransplant.

We prospectively evaluated the efficacy of T-cell-depleted bone marrow transplantation (BMT) in adults with de novo acute nonlymphocytic leukemia (ANLL) in first complete remission (CR), with regard to relapse-free survival and incidence of graft-versus-host disease (GvHD). Thirty-one patients older than 16 years (range, 16.5 to 43.2) received T-cell-depleted grafts for this purpose from related HLA/MLC- compatible donors. Twelve of the patients were older than 30 years at the time of transplantation. Patients were prepared with hyperfractionated total body irradiation (HFTBI; 1,375 to 1,500 cGy) and high-dose cyclophosphamide (120 mg/kg). T cells were removed from the marrow grafts by a two-step soybean lectin agglutination and sheep red blood cell (sRBC)-rosette procedure, achieving a 2.5- to 3-log depletion of clonable T lymphocytes. No additional prophylaxis against GvHD was administered. The median age at transplantation was 28.8 years; the median interval from diagnosis to transplantation was 3.8 months, and from CR was 2.7 months. Seventy-four percent received consolidation after remission induction therapy. The product-limit estimate of disease-free survival (DFS) at 3 years is 45% (95% confidence interval [CI], 24% to 66%), and the cause-specific probability of relapse is 13%. The median follow-up of the survivors is 72 months (range, 34.5 to 95.6). Median time to achieve a sustained absolute neutrophil count of 500 or greater was 16 days, and to maintain an untransfused platelet count of 20,000 or greater was 20 days. Five patients suffered immune-mediated graft rejection. Three patients developed grade I to II acute GvHD limited to the skin, which resolved promptly with brief courses of systemic steroids. None of the patients has developed clinically apparent chronic GvHD or a secondary lymphoproliferative disorder, and no patient is receiving immunosuppressive therapy. T-cell-depleted BMT by the method reported here is a favorable option as postremission therapy for adults with de novo ANLL in first remission who have an HLA/MLC-compatible related donor, and it is not associated with an increased risk of relapse posttransplant.