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 describe the effects of 4-hydroperoxycyclophosphamide (4-HC) on the hematopoietic and stromal elements of human bone marrow. Marrow cells were exposed to 4-HC and then assayed for mixed (CFU-Mix), erythroid (BFU-E), granulomonocytic (CFU-GM), and marrow fibroblast (CFU-F) colony-forming cells and studied in the long-term marrow culture (LTMC) system. The inhibition of colony formation by 4-HC was dose and cell- concentration dependent. The cell most sensitive to 4-HC was CFU-Mix (ID50 31 mumol/L) followed by BFU-E (ID50 41 mumol/L), CFU-GM (ID50 89 mumol/L), and CFU-F (ID50 235 mumol/L). In LTMC, a dose-related inhibition of CFU-GM production was noted. Marrows treated with 300 mumol/L 4-HC were completely depleted of CFU-GM but were able to generate these progenitors in LTMC. Marrow stromal progenitors giving rise to stromal layers in LTMC, although less sensitive to 4-HC cytotoxicity, were damaged by 4-HC also in a dose-related manner. Marrows treated with 4-HC up to 300 mumol/L, gave rise to stromal layers composed of fibroblasts, endothelial cells, adipocytes, and macrophages. Cocultivation experiments with freshly isolated autologous hematopoietic cells showed that stromal layers derived from 4-HC- treated marrows were capable of sustaining the long-term production of CFU-GM as well as controls. In conclusion: (1) Hematopoietic progenitors cells, CFU-Mix, BFU-E, and CFU-GM, are highly sensitive to 4-HC, whereas marrow stromal progenitor cells are relatively resistant. (2) Marrows treated with 300 mumol/L 4-HC that are depleted of CFU-Mix, BFU-E, and CFU-GM can generate CFU-GM in LTMC, suggesting that most primitive hematopoietic stem cells (not represented by CFU-Mix) are spared by 4-HC up to this dose. (3) Consequently, the above colony assays are not suitable tools for predicting pluripotent stem cell survival after 4-HC treatment in vitro.

We report the results of a preclinical study comparing four different purging protocols using a promyelocytic human cell line HL-60 and myeloid leukemic progenitor cells (colony-forming unit-leukemic [CFU- L]) from acute myelogenous leukemia (AML) patients assayed in semisolid culture. We studied the antileukemic effect of (1) Single-cycle complement-mediated lysis by two different monoclonal antibodies (MoAbs) (M195 [CD33] and F23 [CD13] 40 micrograms/mL), reactive with distinct antigens found on early myeloid cells and monocytes, used alone and in combinations; (2) 4-Hydroperoxycyclophosphamide (4-HC) (80 mumol/L or 100 mumol/L) alone; or (3) combined with VP-16 (5 micrograms/mL) and (4) a cocktail of 1 through 3 as above (combined immunochemotherapy). More than 4 logs of HL-60 tumor cell elimination were observed after 1 hour of incubation with both MoAbs plus 4-HC + VP- 16 while the single treatment (immunotherapy or chemotherapy) provided 1.5 and 3.5 logs of colony-forming inhibition, respectively. When the same protocols were tested on cryopreserved leukemic cells from eight patients with AML, we observed a mean value of CFU-L inhibition of 92.3% +/- 2.5% SD, 95.5% +/- 1.4% SD, and 99% +/- 0.8% SD after MoAbs and complement lysis, 4-HC, and 4-HC + VP-16 treatment, respectively. The combined treatment of MoAbs and 4-HC + VP-16 produced more than 3- log reduction of CFU-L colony formation. By comparison, the mean recovery of committed normal bone marrow progenitors after incubation with MoAbs and complement was 12% for CFU-granulocyte-macrophage (CFU- GM), 22.9% for burst-forming unit erythroid (BFU-E), and the recovery following 4-HC + VP-16 treatment was 4.4% for CFU-GM and 5.6% BFU-E. In subsequent experiments, highly purified CD34+ blast cells, enriched by positive selection, and stimulated in liquid culture by cytokines (interleukin-1 [IL-1], IL-3, and combination of both) or MO-conditioned medium (MoCM), demonstrated that immunochemotherapy spares hematopoietic colony-forming cells earlier than day 14 CFU-GM, in vitro.

We evaluated the potential role of photoradiation therapy with a benzoporphyrin derivative, monoacid ring A (BPD-MA), and dihematoporphyrin ether (DHE), for the ex vivo purging of residual tumor cells from autologous bone marrow (BM) grafts. BPD-MA and DHE photosensitizing activity was tested against two human large-cell lymphoma cell lines and colony-forming unit-leukemia (CFU-L) derived from patients with acute myelogenous leukemia (AML). In mixing experiments, 4-log elimination of tumor cell lines was observed after 1 hour of incubation with 75 ng/mL of BPD-MA or 30 minutes of treatment with 12.5 micrograms/mL of DHE followed by white light exposure. By comparison, using the same concentration of BPD-MA, the mean recovery of normal BM progenitors was 4% +/- 0.8% (mean +/- SD) for granulocyte- macrophage colony-forming unit (CFU-GM) and 5% +/- 0.8% for burst- forming unit-erythroid (BFU-E). Similarly, DHE treatment resulted in the recovery of 5.2% +/- 2% and 9.8% +/- 3% of CFU-GM and BFU-E, respectively. Furthermore, equivalently cytotoxic concentrations of both DHE and BPD-MA and light were found not to kill normal pluripotent stem cells in BM, as demonstrated by their survival in two-step long- term marrow culture at levels equal to untreated controls. The T- lymphoblastic leukemia cell line CEM and its vinblastine (VBL)- resistant subline CEM/VBL, along with the acute promyelocyte leukemia cell line HL-60 and its vincristine (VCR)-resistant subline HL-60/VCR, were also tested. BPD-MA at 75 ng/mL was able to provide a greater than 4-log elimination of the drug-sensitive cell lines, but only a 34% and 55% decrease of the drug-resistant HL-60/VCR and CEM/VBL cell lines, respectively. On the contrary, 12.5 micrograms/mL of DHE reduced the clonogenic growth of all the cell lines by more than 4 logs. Further experiments demonstrated decreased uptake of both BPD-MA and DHE by the resistant cell lines. However, all the cell lines took up more DHE than BPD-MA under similar experimental conditions. Our results demonstrate the preferential cytotoxicity of BPD-MA and DHE toward neoplastic cell lines and CFU-L from AML patients. In addition, DHE was slightly more effective in purging tumor cells expressing the p-170 glycoprotein. These results suggest that photoradiation with DHE would be useful for in vitro purging of residual drug-resistant leukemia and lymphoma cells.

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.