Purified primitive human hematopoietic progenitor cells with long-term in vitro repopulating capacity adhere selectively to irradiated bone marrow stroma.

We enriched bone marrow cells from 10 normal individuals for primitive hematopoietic progenitors using a two-step technique, and examined resultant primitive progenitors for their in vitro long-term repopulating capacity and their ability to adhere to irradiated stroma. Immunomagnetic depletion of mature myeloid and lymphoid progenitors resulted in a lineage-negative (Lin-) cell population. Subsequent dual-color fluorescence activated sorting of cells with low forward and vertical light scatter properties, expressing CD34 antigen (34+) and either bearing (DR+) or lacking (DR-) the HLA-DR antigen, resulted in the selection of Lin-34+ DR+ and Lin-34+ DR- cell populations. When the Lin-34+ DR+ cell fraction was cultured in a short-term methylcellulose assay, we demonstrated a 61-fold enrichment for colony forming cells (CFC) compared with undepleted bone marrow mononuclear cells. In contrast to the Lin-34+ DR+ cells, direct culture of Lin-34+ DR- cells in short-term methylcellulose generated significantly less CFC (p less than or equal to 0.001). We then compared the capacity of Lin-34+ DR+ and Lin-34+ DR- cells to generate sustained hematopoiesis when plated in long-term bone marrow culture (LTBMC). When LTBMC were initiated with plated Lin-34+ DR+ cells, we recovered high numbers of CFC during the first week, but observed a rapid decline in the number of harvested CFC over the following weeks. No CFC could be recovered after week 7. In contrast, LTBMC initiated with plated Lin-34+ DR- cells yielded significantly greater numbers of CFC than LTBMC initiated with plated Lin-34+ DR+ cells (p less than or equal to 0.001), and this was sustained for at least 12 wk of culture. The Lin-34+ DR+ population was only 6.6-fold enriched for primitive progenitors capable of initiating and sustaining hematopoiesis in LTBMC when compared with undepleted bone marrow mononuclear cells, while the Lin-34+ DR- population was 424-fold enriched for such primitive progenitors (p less than or equal to 0.001). Finally, we examined the capacity of both Lin-34+ DR+ and Lin-34+ DR- populations to adhere to irradiated allogeneic stroma. We used a previously described "panning method" in which cells are plated onto stroma for 2 h, the nonadherent cells removed by extensive washing, and the adherent fraction maintained under conditions favoring LTBMC growth. When stroma was panned with Lin -34+ DR+ cells, 79 +/- 10% of the cells were recovered in the panning effluent. In contrast, when stroma was panned with Lin -34 + DR- cells, significantly fewer (37 +/- 7%) (p less than or equal to 0.001) cells were recovered in the panning effluent. Unlike LTBMC initiated with plated Lin -34 + DR+ cells, virtually no CFC were recovered from LTBMC initiated with panned Lin -34 + DR+ cells.(ABSTRACT TRUNCATED AT 400 WORDS)

Differentiation of primitive human multipotent hematopoietic progenitors into single lineage clonogenic progenitors is accompanied by alterations in their interaction with fibronectin.

We have previously demonstrated that primitive progenitors from human bone marrow termed long term bone marrow culture initiating cells (LTBMC-IC) adhere avidly to irradiated bone marrow stroma, while more mature clonogenic progenitors fail to do so. In this study we examine the interaction between these progenitors and components of the bone marrow stroma. (a) We demonstrate that both primitive LTBMC-IC and more mature clonogenic progenitors adhere to intact fibronectin. (b) Primitive LTBMC-IC and multi-lineage CFU-MIX progenitors adhere to the 33/66 kD COOH-terminal heparin-binding cell-adhesion promoting fragment of fibronectin, but adhere significantly less to its 75 kD RGDS-dependent cell-binding fragment. In contrast, more differentiated single-lineage progenitors adhere equally well to the 33/66 kD RGDS independent and the 75 kD RGDS-dependent cell-adhesion fragments of fibronectin. (c) Both primitive LTBMC-IC and clonogenic progenitors adhere to the three known cell-attachment sites in the 33/66 kD cell-adhesion promoting fragment, FN-C/H I, FN-C/H II and CS1. However, LTBMC-IC and CFU-MIX progenitors adhere significantly better to FN-C/H II than to the flanking FN-C/H I and CS1 cell-attachment sites. In contrast, single-lineage progenitors adhere equally well to all three cell attachment sites in the 33/66 kD cell-adhesion promoting fragment. (d) Finally, adhesion of primitive LTBMC-IC to intact irradiated stroma can be inhibited partially by peptide FN-C/H II and almost completely by a combination of FN-C/H II and peptide FN-C/H I and CS1. This study demonstrates that adhesive interactions between primitive hematopoietic progenitors and the extracellular matrix component fibronectin can occur. Specific changes in adhesion to the 33/66 kD cell-adhesion promoting fragment and the 75 kD RGDS-dependent cell-adhesion fragment of fibronectin are associated with differentiation of primitive multi-lineage progenitors into committed single-lineage progenitors. Such differences in adhesive interaction with fibronectin may allow hematopoietic progenitors at various stages of differentiation to interact with specific supportive loci of the bone marrow microenvironment. Finally, the ability to block adhesion of LTBMC-IC to intact irradiated stroma with peptides FN-C/H II, FN-C/H I and CS1 suggests that receptors responsible for this interaction may be important in the homing of primitive progenitors to the bone marrow.

Treatment of marrow stroma with interferon-alpha restores normal beta 1 integrin-dependent adhesion of chronic myelogenous leukemia hematopoietic progenitors. Role of MIP-1 alpha.

The mechanisms by which interferon-alpha (IFN-alpha) restores normal hematopoiesis in chronic myelogenous leukemia (CML) are not well understood. We have recently demonstrated that IFN-alpha acts directly on CML hematopoietic progenitors to restore their adhesion to marrow stroma by modulating beta 1 integrin receptor function. In the present study we examined the effect of IFN-alpha treatment of marrow stroma on subsequent adhesion of CML progenitors. Stromal layers were preincubated with IFN-alpha (10,000 microns/ml) for 48 h. Subsequent coincubation with CML progenitors for 2 h resulted in significantly increased adhesion of CML progenitors. We demonstrated that alpha 4 beta 1 and alpha 5 beta 1 integrin receptors were involved in the enhanced adhesion of CML progenitors, suggesting that IFN-alpha-treated stroma can upregulate CML integrin function. This effect is due, at least in part, to IFN-alpha-induced increased stromal production of the chemokine macrophage inflammatory protein-1 alpha (MIP-1 alpha), which upregulates beta 1 integrin-dependent adhesion of CML progenitors to stroma. Thus, IFN-alpha treatment of marrow stroma restores beta 1 integrin-dependent adhesion of CML progenitors, at least in part through induction of MIP-1 alpha production. These observations provide further insights into mechanisms by which IFN-alpha may restore normal hematopoiesis in CML.

Mechanisms underlying abnormal trafficking of malignant progenitors in chronic myelogenous leukemia. Decreased adhesion to stroma and fibronectin but increased adhesion to the basement membrane components laminin and collagen type IV.

We studied the adhesion of primitive and committed progenitors from chronic myelogenous leukemia (CML) and normal bone marrow to stroma and to several extracellular matrix components. In contrast to benign primitive progenitors from CML or normal bone marrow, Ph1-positive primitive progenitors from CML bone marrow fail to adhere to normal stromal layers and to fibronectin and its proteolytic fragments, but do adhere to collagen type IV, an extracellular matrix component of basement membranes. Similarly, multilineage colony-forming unit (CFU-MIX) progenitors from CML bone marrow do not adhere to fibronectin or its adhesion promoting fragments but adhere to collagen type IV. Unlike committed progenitors from normal bone marrow, CML single-lineage burst-forming units-erythroid and granulocyte/macrophage colony-forming units fail to adhere to fibronectin or its components but do adhere to both collagen type IV and laminin. Evaluation of adhesion receptor expression demonstrates that fibronectin receptors (alpha 4, alpha 5, and beta 1) are equally present on progenitors from normal and CML bone marrow. However, a fraction of CML progenitors express alpha 2 and alpha 6 receptors, associated with laminin and collagens, whereas these receptors are absent from normal progenitors. These observations indicate that the premature release of malignant Ph1-positive progenitors into the circulation may be caused by loss of adhesive interactions with stroma and/or fibronectin and acquisition of adhesive interactions with basement membrane components. Further study of the altered function of cell-surface adhesion receptors characteristic of the malignant clone in CML may lead to a better understanding of the mechanisms underlying both abnormal expansion and abnormal circulation of malignant progenitors in CML.

Interferon-alpha restores normal adhesion of chronic myelogenous leukemia hematopoietic progenitors to bone marrow stroma by correcting impaired beta 1 integrin receptor function.

Treatment of chronic myelogenous leukemia (CML) with interferon-alpha frequently results in normalization of peripheral blood counts and, in up to 20% of patients, reestablishment of normal hematopoiesis. We hypothesize that interferon-alpha may restore normal adhesive interactions between CML progenitors and the bone marrow microenvironment and restore normal growth regulatory effects resulting from these progenitor-stroma interactions. We demonstrate that treatment with interferon-alpha induces a significant, dose-dependent increase in the adhesion of primitive long-term culture initiating cells and committed colony-forming cells (CFC) from CML bone marrow to normal stroma. Adhesion of CFC seen after interferon-alpha treatment could be inhibited by blocking antibodies directed at the alpha 4, alpha 5, and beta 1 integrins and vascular cell adhesion molecule, but not CD44 or intracellular adhesion molecule, suggesting that interferon-alpha induces normalization of progenitor-stroma interactions in CML. Because FACS analysis showed that the level of alpha 4, alpha 5, and beta 1 integrin expression after interferon-alpha treatment is unchanged, this suggests that interferon-alpha may restore normal beta 1 integrin function. Normalization of interactions between CML progenitors and the bone marrow microenvironment may then result in the restoration of normal regulation of CML progenitor proliferation, and explain, at least in part, the therapeutic efficacy of interferon-alpha in CML.

Studies on the liver to kidney switch of erythropoietin production.

Although the liver is the major site of erythropoietin (Ep) production in the fetus, this function is assumed by kidneys in the adult. The mechanisms underlying the liver to kidney switch of Ep formation are not understood. We studied the natural progression of this transition in sheep by measuring Ep production in response to anemia in normal and bilaterally nephrectomized fetal and newborn sheep beginning at about 80 d gestation (normal gestation: 140 d). Removal of both kidneys before induction of anemia did not affect Ep formation up to about 120 d of gestation. A significant reduction (29%, P < 0.02) in Ep synthesis was first noted at about 130 d of gestation (initiation of switch). This level of nephrectomy-induced reduction of Ep formation persisted until about 15 d after birth. Thereafter, bilateral nephrectomy caused further significant decreases (P < 0.05) in Ep production, gradually resulting in near total absence of Ep production at about day 40 postpartum (completion of switch). Chronic administration of testosterone (12 mg/wk) or estradiole benzoate (1.5 mg/d, 5 d/wk) to the fetus/newborn beginning at 85-90 d of gestation enhanced or suppressed erythropoiesis, respectively, but failed to affect the time at which the liver to kidney switch was initiated and/or completed. By contrast, a significant delay (P < 0.001) in the onset, but not completion of the switch occurred in animals that were either thyroidectomized or rendered chronically anemic beginning in the second third of the gestation period. Administration of thyroxin (1.2 mg/d, 5 d/wk) to thyroidectomized fetus/newborns not only prevented the delay in the initiation of the switch, but also accelerated the rate at which the switch was completed. These results demonstrate that in sheep (a) the liver to kidney switch of Ep production is initiated in utero during the last third of the gestation period, but is completed after birth, (b) this transition occurs gradually; the assumption of Ep producing capacity by the kidney is not preceded by an abrupt loss of hepatic Ep formation; and (c) the switch is not affected by changes in sex hormone levels during the prenatal-postnatal growth periods, but is profoundly influenced by alterations in thyroid hormone and oxygen supply-demand levels.

Difficult stem cell mobilization despite adequate CD34+ cell dose predicts shortened progression free and overall survival after autologous HSCT for lymphoma.

Hematopoietic growth factors alone or in combination with myelosuppressive chemotherapy are used to mobilize peripheral blood stem cells for autologous transplantation. To identify characteristics of successful mobilization with granulocyte colony-stimulating factor (G-CSF) alone and to study the impact of immediate chemotherapy mobilization following G-CSF mobilization, we treated 175 chemotherapy sensitive lymphoma patients with G-CSF (G) mobilization and leukapheresis followed by chemotherapy plus G-CSF (CG) mobilization and leukapheresis and then autologous transplantation. Patients with stage I/II disease at diagnosis and < or =5 years from diagnosis were more likely to mobilize successfully with G-CSF alone (G). CG mobilization led to superior stem cell yields compared to the preceding mobilization with G (median 2.37 vs 1.37 ( x 10(6)CD34+ cells/kg); P<0.0001). Patients (n=58, 33%) with successful G-CSF mobilization (> or =2 x 10(6) CD34+ cells/kg) had quicker platelet recovery and improved progression free and overall survival compared to patients who had adequate collection only after chemotherapy mobilization or to those who failed to collect an adequate graft with either type of mobilization. The poor clinical outcome of patients with difficult mobilization using either method identifies them as a high-risk group who might benefit from alternative therapies.

Prevalence of conception and pregnancy outcomes after hematopoietic cell transplantation: report from the Bone Marrow Transplant Survivor Study.

We conducted a retrospective study to describe the magnitude of compromise in reproductive function and investigate pregnancy outcomes in 619 women and partners of men treated with autologous (n=241) or allogeneic (n=378) hematopoietic cell transplantation (HCT) between 21 and 45 years of age, and surviving 2 or more years. Median age at HCT was 33.3 years and median time since HCT 7.7 years. Mailed questionnaires captured pregnancies and their outcomes (live birth, stillbirth, miscarriage). Thirty-four patients reported 54 pregnancies after HCT (26 males, 40 pregnancies; eight females, 14 pregnancies), of which 46 resulted in live births. Factors associated with reporting no conception included older age at HCT (> or =30 years: odds ratio (OR)=4.8), female sex (OR=3.0), and total body irradiation (OR=3.3). Prevalence of conception and pregnancy outcomes in HCT survivors were compared to those of 301 nearest-age siblings. Although the risk for not reporting a conception was significantly increased among HCT survivors (OR=36), survivors were not significantly more likely than siblings to report miscarriage or stillbirth (OR=0.7). Although prevalence of conception is diminished after HCT, if pregnancy does occur, outcome is likely to be favorable. Patients should be counseled prior to transplant regarding strategies to preserve fertility.

Unrelated-donor bone marrow transplantation for Philadelphia chromosome-positive chronic myelogenous leukemia in children.

PURPOSE: Bone marrow transplantation (BMT) for Philadelphia chromosome-positive (Ph1) chronic myelogenous leukemia (CML) results in a 55% to 64% disease-free survival (DFS) rate in 20% to 30% of cases with a matched-sibling donor (MSD). Studies that include primarily adults with CML, using unrelated-donor (URD) BMT, have expanded this option to those without an MSD. We review and compare the efficacy of URD and MSD BMT in children with Ph1 CML. PATIENTS AND METHODS: Eleven children with URD BMTs were reviewed and compared with 11 children with MSD BMTs for Ph1 CML. Among the URD BMT recipients, there were three with fully matched marrows and 10 with advanced CML. The median time from diagnosis to transplant was 2.6 years. Among the MSD BMT recipients, 11 had fully matched marrows and five had advanced CML. The median time from diagnosis to BMT was 0.7 years. All received non-T-depleted marrows after cyclophosphamide and fractionated total-body irradiation. RESULTS: Both groups had similar engraftment times. Late graft failure occurred in two URD patients. Graft-versus-host disease (GVHD), > or = grade II, was similar in both groups (77% for URD BMT, 45% for MSD BMT), although more severe acute disease and more persistent chronic disease was seen in the URD group. The Kaplan-Meier estimate of DFS was 45% +/- 15% (SE) and 78% +/- 14% (SE) in the URD and MSD groups, respectively, at 3 years. All had Karnofsky scores of more than 70%, except one URD patient debilitated from GVHD. CONCLUSION: CML is eventually fatal to all patients without BMT. The high survival rate seen among children who receive a URD BMT, despite several adverse factors, opens this important therapeutic option to those without an MSD.

A critical comparison of allogeneic bone marrow transplantation and conventional chemotherapy as treatment for acute nonlymphocytic leukemia.

Published data from two centers conducting bone marrow transplantation on patients with acute nonlymphocytic leukemia in first remission were pooled and compared with results from an Eastern Cooperative Oncology Group (ECOG) study in which patients were treated with conventional chemotherapy. A series of adjustments were made to the ECOG sample to account for selection factors that restrict access of patients to transplantation. The transplant sample exhibits considerably higher disease-free survival when compared to the adjusted ECOG series (53% versus 21% at three years). The transplant series is somewhat younger than the ECOG series (median, 24 years versus 28 years). The impact of age on the disease-free survival results is difficult to assess because of the relatively small samples in the different age groups. However, by defining a suitable control group, methodology for making a critical comparison between the two modalities is presented which, if applied to larger samples of patients, should help to resolve the issue. In the absence of data from a large, prospective randomized study, a critical retrospective comparison of available data is essential in the assessment of treatment options.

Allogeneic bone marrow transplantation for acute lymphoblastic leukemia in remission: prolonged survival associated with acute graft-versus-host disease.

Forty remission patients with high-risk acute lymphoblastic leukemia (ALL) underwent matched allogenic bone marrow transplantation (BMT) following preparation with cyclophosphamide and fractionated total body irradiation (TBI). As of March 1987, the median follow-up is more than 3 1/2 years. Thirteen patients are alive (11 relapse free) between 2 and 4 1/2 years post-BMT. Neither age, sex, remission number, prior extramedullary leukemia, nor WBC at diagnosis of ALL was statistically significant as a predictor of relapse-free survival. The development of acute graft-v-host disease (GVHD) in 17 patients was found, with time-dependent Cox regression analysis, to be associated with a significant reduction in post-BMT relapse risk (P = .04) and improved disease-free survival (P = .11). A prospective, randomized trial of maintenance chemotherapy with oral methotrexate and mercaptopurine did not demonstrate improvement in relapse risk or survival for those assigned maintenance chemotherapy (P = .7). These results suggest that allogeneic BMT can result in extended relapse-free survival for some patients with high-risk ALL. More effective preparative chemoradiotherapy and exploitation of the apparent graft-v-leukemia effect may be useful in future trials.

Therapy of chronic myelogenous leukemia with allogeneic bone marrow transplantation.

From December 1982 to January 1986, 57 patients received allogeneic bone marrow transplantation as therapy for Philadelphia chromosome (Ph') positive chronic myelogenous leukemia (CML). All patients were prepared for transplantation with cyclophosphamide 60 mg/kg (day -6, -5) and fractionated total body irradiation, 165 cGy twice daily (day -4, -3, -2, -1) and received major histocompatibility (MHC) matched donor marrow (day 0). All patients received graft-v-host disease (GVHD) prophylaxis with methotrexate, prednisone, and either antithymocyte globulin (ATG) (55 patients) or OKT3 infusion (two patients). The projected survival of 29 chronic phase patients is 64% (95% confidence interval [Cl] 42% to 86%); and of 28 accelerated phase patients, 30% (95% Cl, 12% to 48%) at 30 months (P = .005). Multivariate regression analysis of pretransplant patient characteristics demonstrated that the presence of chronic phase and age less than 30 years were the only prognostic features studied that independently predicted survival. No evidence of persistent or recurrent disease has occurred in chronic phase patients; however, reappearance of the Ph' was observed in seven accelerated-phase patients, and hematologic relapse occurred in three of these seven patients. The incidence of grade II to IV acute GVHD is 63% (95% Cl, 50% to 76%) at 100 days, and that of extensive chronic GVHD is 53% (95% Cl, 33% to 74%) at 30 months. The median Karnofsky activity assessment of survivors is 100% (range, 60% to 100%), and all activity assessments less than 100% can be attributed to complications of GVHD. Bone marrow transplantation therapy for CML after preparation with cyclophosphamide and fractionated total body irradiation results in a high proportion of disease-free survival in chronic-phase patients. Survival in accelerated phase is significantly worse and is associated with relapse. GVHD has emerged as a significant cause of morbidity and mortality in this study.

Maintenance chemotherapy prolongs remission duration in adult acute nonlymphocytic leukemia.

The value of maintenance therapy after the achievement of complete remission in adult acute nonlymphocytic leukemia (ANLL) has never been clearly established. A randomized Eastern Cooperative Oncology Group (ECOG) study of postremission therapy compared outcomes in patients who received no further therapy to those administered long-term maintenance chemotherapy. Adverse results in the group administered no further therapy led to early termination of this trial after only 51 patients were randomized. Patients receiving no postremission therapy experienced significantly inferior remission durations (P = .002) compared with patients receiving maintenance therapy. All 26 patients in the group administered no postremission therapy have relapsed, with a median duration of remission of 4.1 months. In contrast, four of 25 patients (16%) who received maintenance therapy remain disease free, with a median duration of remission of 8.1 months.

Unrelated donor bone marrow transplantation for children with acute leukemia.

PURPOSE: To test the use of unrelated donor bone marrow transplantation (URD BMT) to cure children with high-risk acute leukemias. PATIENTS AND METHODS: Between June 1985 and December 1994, 50 children with acute leukemia (15 acute myelogenous leukemia [AML], 35 acute lymphoblastic leukemia [ALL]; 22 greater than second complete remission [CR]) received BMT from a URD at the University of Minnesota. Ages ranged from 0.9 to 17.5 years (median, 8.8). Median follow-up is 2.1 years (range, 1 to 7.3). Thirty patients (60%) received bone marrow fully matched at HLA-A,B and DRB1; 20 (40%) received bone marrow with a major or minor mismatch at a single HLA-A or B locus. RESULTS: The median time to neutrophil engraftment was day 24 (range, 14 to 42 days) in those receiving matched and day 25 (range, 15 to 32 days) in those receiving mismatched marrow (P = .35). The incidence of grades III to IV graft-versus-host disease (GVHD) was 23% (95% confidence interval [CI], 7% to 39%) in matched and 32% (95% CI, 8% to 52%) in HLA-mismatched patients (P = .57). The incidence of chronic GVHD was 50% (95% CI, 28% to 72%) in matched and 57% (95% CI, 23% to 91%) in mismatched patients (P = .80). Disease-free survival for patients with ALL is 37% (95% CI, 21% to 53%) at 1 year and 30% (95% CI, 15% to 46%) at 2 years; for patients with AML, 53% (95% CI, 28% to 78%) at 1 year and 33% (95% CI, 6% to 60%) at 2 years. CONCLUSION: URD BMT is an effective treatment for children with poor-prognosis acute leukemia and should be considered for all high-risk patients. Early referral of patients is strongly recommended.

Results of autologous and allogeneic hematopoietic cell transplant therapy for multiple myeloma.

We compared the results of autologous and allogeneic peripheral blood hematopoietic cell transplant (HCT) in 87 patients with multiple myeloma using myeloablative preparative regimen. Autologous transplant (n=70) led to a lower 100-day transplant-related mortality (TRM) of 4% [0-9%] compared to 18% [0-36%] in allogeneic recipients (P=0.02). More frequent complete responses were seen in allogeneic recipients (64% [37-91%] vs 34% [23-45%] in autologous recipients, P=0.09). In autologous recipients, survival at 1 year was 86% [80-95%] and, it fell to 50% [47-75%] at 4 years, whereas in allogeneic recipients, survival at 1 and 4 years remained at 64% [40-87%]. In patients surviving more than one year, 4-year survival was superior in allogeneic (100%) vs autologous recipients (58% [41-75%], P=0.02). A trend toward higher relapse was seen in autologous transplant patients (73% [55-90%] vs 37% [11-63%] in allogeneic transplant patients, P=0.1). We observed good tolerance of myeloablative conditioning regimen followed by either autologous or allogeneic transplant. Although autologous HCT is associated with lower TRM, allogeneic HCT has acceptable TRM, and is more likely to provide a sustained response. Allogeneic HCT may be suitable in younger patients, soon after diagnosis, and in those with chemosensitive disease.

Unrelated donor and autologous marrow transplant therapy of chronic myelogenous leukemia (CML).

Marrow transplant from an HLA-matched sibling donor can cure CML. Best results are observed when patients are transplanted early in chronic phase. T-lymphocyte depletion of donor marrow can effectively prevent chronic graft versus host disease, but is associated with a high incidence of relapse. Hematologic relapse after marrow transplantation can be treated successfully with alpha-interferon, donor buffy coat cells or second transplant. HLA phenotypically matched and, in some cases, 1 HLA antigen mismatched unrelated donors can also be used successfully for marrow transplantation therapy of CML. Complications include an increased incidence of graft failure and graft vs. host disease. Chronic phase patients transplanted early in the disease course have the best outcome. The development of the National Marrow Donor Program in the United States and a network of donor registries throughout the world as well as the establishment of new techniques for histocompatibility testing will increase the availability of unrelated donors and expedite the donor search process. Autologous marrow transplantation can induce complete hematologic and cytogenetic remissions and may prolong survival when compared with results expected from conventional therapy for CML. Strategies are being developed to obtain benign primitive progenitors suitable for autologous marrow transplantation by positive selection techniques and to develop further post-transplant anti-leukemia cell therapy to use as an adjunct to autologous marrow transplantation for CML.

T lymphocytes cultured from chronic myelogenous leukemia bone marrow suppress autologous hematopoietic progenitors.

In vitro culture of T lymphocytes infiltrating solid tumors has resulted in populations with significant, and sometimes selective, anti-tumor activity. In this study we evaluated the ability of T lymphocyte populations generated from the marrow of patients with chronic myelogenous leukemia (CML) to suppress autologous hematopoietic progenitors. T lymphocyte populations were obtained by culture of CML bone marrow mononuclear cells (BMMNC) with low dose rIL-2 (25 U/ml) after initial PHA stimulation, and restimulation during culture with autologous marrow cells. Preincubation of the cultured CML T lymphocytes in close contact with autologous BMMNC resulted in significant, dose-related suppression of autologous CFU-MIX and BFU-E colonies (P < 0.001). Close contact between effectors and targets was important for progenitor suppression. Progenitor suppression was mediated by CD4-positive T lymphocytes. In contrast to the significant suppression of autologous progenitors by CML T lymphocytes, T lymphocytes from normal bone marrow did not suppress autologous progenitors. We conclude that T lymphocyte populations with significant autologous progenitor suppressing ability can be generated from CML marrow. These observations may be of therapeutic value in CML.

Escalating the intensity of post-remission therapy improves the outcome in acute myeloid leukemia: the ECOG experience. The Eastern Cooperative Oncology Group.

These ECOG trials have demonstrated that progressive increments in the intensity of post-remission therapy result in improving long-term, disease-free survival in adults with AML. The median duration of disease-free survival and long-term outcome from different post-remission therapies are summarized in Table 4. [table: see text] Despite the suggestive evidence of the ordered increment in value of intensive consolidation therapy, allogeneic and autologous bone marrow transplantation, it remains to be proved that the differences observed in our preceding studies are statistically significant and clinically meaningful. These remaining questions led to the current ECOG study, EST 3489, a randomized intergroup study conducted with members of the Southwest Oncology Group. The study includes all patients with de novo AML up to age 55; the schema is shown in Figure 3. Induction therapy consists of idarubicin plus cytarabine instead of DAT. A modified short course of this induction therapy is repeated after CR. Patients who have a histocompatible sibling are offered allogeneic bone marrow transplantation. The remaining patients are randomized to receive either autologous bone marrow transplantation or a single course of high-dose cytarabine. Autologous bone marrow transplantation utilizes the previously described high-dose busulfan and cyclophosphamide regimen plus 4-HC purging of the bone marrow. The dosage of cytarabine in the intensive consolidation arm is 3 gm/M2/day IV on days 1-6. The results of this study should determine the relative merits of these different approaches to post-remission therapy. [table: see text] As mentioned earlier, demonstration of improved CR rates is limited by the morbidity and mortality from the myelosuppression that results from induction therapy. This is especially marked for older patients with AML. In patients, ages 55-70 years old, the ECOG is conducting a randomized trial (EST 1490) of conventional induction therapy +/- GM-CSF to determine if accelerated neutrophil recovery can reduce the mortality of induction therapy and thereby increase the remission rate. It may be that the application of GM-CSF and other colony-stimulating factors can increase the CR rate for all patients, increasing the number of patients potentially eligible for cure by post-remission therapy.

Effect of recombinant gamma interferon on chronic myelogenous leukemia bone marrow progenitors.

In order to understand its mechanism of action and explore its potential as a therapeutic agent, we studied the effect of recombinant gamma interferon (IFN) on in vitro proliferation and on karyotype of bone marrow-derived hematopoietic stem cell progenitors (BFUe, CFUmix) obtained from patients with Ph1-positive chronic myelogenous leukemia (CML). Addition of IFN to culture resulted in a dose-dependent inhibition of both normal and CML BFUe and CFUmix. The maximum dose-dependent suppression of CML BFUe (92% +/- 4%) and CML CFUmix (100%) exceeded the maximum suppression of normal BFUe (40% +/- 4%) and normal CFU mix (68% +/- 6%) (p less than 0.001 and p = 0.008). In parallel studies, CML BFUe and CFUmix were cultured with and without IFN, and cells recovered from culture were examined cytogenetically. Treatment of CML bone marrow cells (BMC) with IFN resulted in an increase in the proportion (p less than 0.001) of Ph1-negative metaphases when compared to control cells grown in the absence of IFN. Recombinant gamma interferon has a significant antiproliferative effect against CML bone marrow-derived stem cell progenitors in vitro, and the addition of this agent to culture increases our ability to identify a cell population derived from a Ph1-negative progenitor pool. Recombinant gamma interferon may selectively spare Ph1-negative hematopoietic progenitors, and may be an active agent in the treatment of CML.

A clinically suitable ex vivo expansion culture system for LTC-IC and CFC using stroma-conditioned medium.

FACS-selected CD34+ HLA-DR- cells (DR- cells) may provide a source of benign stem cells suitable for autografting in chronic myelogenous leukemia (CML) and other hematological malignancies. However, DR- cell selection depletes the majority of committed hematopoietic progenitors, which may be important for early engraftment. Furthermore, only a small number of DR- cells may be selectable in certain patients. These impediments to the use of DR- cells for autografting may be overcome through the development of ex vivo culture systems that support expansion and initial differentiation of primitive progenitors. Because 2-week culture of DR- cells in a stroma "noncontact" system supplemented with interleukin-3 (IL-3) and macrophage inflammatory protein 1-alpha (MIP-1alpha) expands both long-term culture-initiating cells (LTC-ICs) and colony-forming cells (CFCs), we adapted this system to a clinically applicable method for expanding LTC-ICs and CFCs ex vivo. In initial small-scale studies, DR cells were grown in stroma conditioned medium (SCM) supplemented with IL-3 with or without additional growth-promoting cytokines and the chemokines PF-4 and BB10010, all approved for clinical use. An IL-3 dose-dependent expansion of committed progenitors and LTC-ICs was observed when DR- cells were cultured in tissue culture plates in SCM+IL-3 for 2 weeks. Similar CFC expansion along with increased (5-fold) LTC-IC expansion was observed following addition of PF-4 to SCM+IL-3 cultures. The addition of stem cell factor (SCF), but not of IL-6, IL-11, granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage (GM)-CSF, IL-1, and IL-7, increased CFC and LTC-IC expansion beyond the levels observed with SCM+IL-3 alone. We next evaluated the suitability of this culture system for scale-up. Culture of 2-6 x 10(5) DR- cells in gas-permeable bags with SCM+IL-3 resulted in similar CFC and LTC-IC expansion as seen in small-scale cultures. In addition, we observed that progenitors capable of differentiating to natural killer (NK)-cells were maintained under these conditions. Finally, we found that BCR/ABL mRNA-negative CFCs and LTC-ICs present in DR- cells selected from steady-state CML marrow could be expanded in large-scale SCM+IL-3 cultures. We conclude that culture of DR- cells for 2 weeks in SCM+IL-3 culture, with or without PF-4 or SCF, results in significant CFC and LTC-IC expansion and lymphoid NK progenitor maintenance. This culture system is readily adaptable to the expansion of primitive progenitors for autotransplantation.