Phase II study of unrelated cord blood transplantation for adults with high-risk hematologic malignancies.

Cell dose is a critical determinant of outcomes in unrelated cord blood (CB) transplantation. We investigated a strategy in which CB units should contain at least 2 x 10(7) total nucleated cells/kg of recipient weight, otherwise a second unit had to be added. We report the results of a study that was prematurely closed owing to toxicity. Patients with advanced hematologic malignancies without a human leukocyte antigen-matched sibling or unrelated donor were eligible. Conditioning regimen consisted of fludarabine and 12 Gy of total body irradiation (n=11), or melphalan (n=4), with antithymocyte globulin. Graft-versus-host disease prophylaxis was tacrolimus and methotrexate. Fifteen patients with acute leukemia (n=9), chronic myelogenous leukemia (n=2), multiple myeloma (n=2) and lymphoma (n=2) were treated; 60% had relapsed disease at transplantation. Three patients received double CB transplants. The 100-day and 1-year treatment-related mortality rates were 40 and 53%, respectively. Median time to neutrophil and platelet engraftment was 22 days (n=10) and 37 days (n=10), respectively. One patient had secondary graft failure and five patients failed to engraft. Two patients are alive and disease free; 4-year actuarial survival is 33 versus 0% for patients transplanted in remission versus in relapse. We concluded that disease status was the main determinant of treatment failure in this study.

Autologous blood stem-cell transplantation in patients with advanced Hodgkin's disease and prior radiation to the pelvic site.

Patients with relapsed Hodgkin's disease who respond to salvage therapy are successfully treated with cyclophosphamide, carmustine (BCNU), and etoposide (VP-16) (CBV) followed by autologus bone marrow transplantation (ABMT). Because of heavy pretreatment including radiation to the pelvic site, marrow harvest was not feasible in those patients. We therefore used blood-derived hemopoietic precursor cells as an alternative stem-cell source to rescue them after superdose chemotherapy. Hemopoietic precursor cells were mobilized into the peripheral blood either by chemotherapeutic induction of transient myelosuppression followed by an overshooting of blood stem-cell concentration, or by continuous intravenous (IV) granulocyte-macrophage colony-stimulating factor (GM-CSF) administration. The median time to reach 1,000 WBC per microliter, 500 polymorphonuclear cells (PMN) per microliter, or 20,000 platelets per microliter was 10, 20.5, and 38 days, respectively, for 50% of all patients. The platelet counts of two patients never dropped below 20,000/microL following autologous blood stem-cell transplantation (ABSCT), whereas two other patients had to be supported with platelets for 75 and 86 days posttransplant until a stable peripheral platelet count of 20,000/microL was attained. Among the 11 assessable patients, seven are in unmaintained complete remission (CR) at a median follow-up of 318 days. This is a first report on a series of ABSCTs in patients with advanced Hodgkin's disease proving that, despite prior damage to the marrow site, the circulating stem-cell pool is still a sufficient source of hemopoietic precursor cells for stem-cell rescue.

Collection of peripheral-blood diploid cells from chronic myelogenous leukemia patients early in the recovery phase from myelosuppression induced by intensive-dose chemotherapy.

PURPOSE: To evaluate whether intensive chemotherapy followed by peripheral stem-cell (PSC) collections during early hematopoietic recovery results in a higher percentage of diploid cell collections in patients with Philadelphia chromosome (Ph)-positive chronic myelogenous leukemia (CML). PATIENTS AND METHODS: Fifty-five adults with Ph-positive CML received intensive chemotherapy with daunorubicin and high-dose cytarabine (ara-C) (DAUNO-HDAC; 26 patients) or fludarabine, high-dose ara-C, and mitoxantrone (FAM; 29 patients). Collections of the peripheral mononuclear cells were initiated when the WBC count was > or = 0.8 x 10(3)/microL. Simultaneous peripheral and marrow samples were subjected to cytogenetic studies. RESULTS: Thirty-eight of 55 patients (69%) were able to undergo the PSC collections. The rate of collection was higher in chronic phase (26 of 30 patients; 87%) than in accelerated (11 of 17; 65%) and blastic phases (1 of 8; 12%). Among the 30 patients in chronic phase, cytogenetic analyses of PSC showed cytogenetic responses (Ph-positive < 95%) in 60%, which were major (Ph < 35%) in 43% and complete (Ph = 0%) in 27%. Seven of 19 patients with simultaneous studies (37%; 23% of total) had a significantly lower percentage of Ph-positive cells in the peripheral collection compared with the marrow collection; one had the reverse phenomenon (5%; 3% of total). Cytogenetic responses were modest in both peripheral and marrow collections in CML accelerated and blastic phases. Myelosuppression-associated complications were frequent, resulting in febrile episodes in 76% of patients. CONCLUSION: PSC collection during early hematopoietic recovery from intensive chemotherapy allowed the collection of diploid-rich stem cells, mostly in chronic-phase CML. The approach could be used for in vivo purging before autologous stem-cell transplantation (ASCT).

Hyper-CVAD and high-dose methotrexate/cytarabine followed by stem-cell transplantation: an active regimen for aggressive mantle-cell lymphoma.

PURPOSE: Diffuse and nodular forms of mantle-cell lymphoma (MCL) are consistently associated with poor prognosis. In an effort to improve the outcome, we adopted a treatment plan that consisted of four courses of fractionated cyclophosphamide (CY) 1,800 mg/m2 administered with doxorubicin (DOX), vincristine (VCR), and dexamethasone (Hyper-CVAD) that alternated with high-dose methotrexate (MTX) and cytarabine (Ara-C). After four courses, patients were consolidated with high-dose CY, total-body irradiation, and autologous or allogeneic blood or marrow stem-cell transplantation. PATIENTS AND METHODS: Forty-five patients were enrolled; 25 patients were previously untreated, 43 patients had Ann Arbor stage IV disease, and 42 patients had marrow involvement. Forty-one patients had diffuse histology, two patients had nodular, and two patients had blastic variants. RESULTS: Hyper-CVAD/MTX-Ara-C induced a response rate of 93.5% (complete response [CR], 38%; partial response [PR], 55.5%) after four cycles of pretransplantation induction chemotherapy. All patients who went on to undergo transplantation achieved CRs. For the 25 previously untreated patients, the overall survival (OS) and event-free survival (EFS) rates at 3 years were 92% (95% confidence interval [CI], 80 to 100) and 72% (95% CI, 45 to 98) compared with 25% (95% CI, 12 to 62; P = .005) and 17% (95% CI, 10 to 43; P = .007), respectively, for the previously treated patients. When compared with a historic control group who received a CY, DOX, VCR, and prednisone (CHOP)-like regimen, untreated patients in the study had a 3-year EFS rate of 72% versus 28% (P = .0001) and a better OS rate (92% v 56%; P = .05). Treatment-related death occurred in five patients: all were previously treated and two received allogeneic transplants. CONCLUSION: The Hyper-CVAD/MTX-Ara-C program followed by stem-cell transplantation is a promising new therapy for previously untreated patients with MCL.

Transplant-lite: induction of graft-versus-malignancy using fludarabine-based nonablative chemotherapy and allogeneic blood progenitor-cell transplantation as treatment for lymphoid malignancies.

PURPOSE: To investigate the use of a nonmyeloablative fludarabine-based preparative regimen to produce sufficient immunosuppression to allow engraftment of allogeneic stem cells and induction of graft-versus-leukemia/lymphoma (GVL) as the primary treatment modality for patients with chronic lymphocytic leukemia (CLL) and lymphoma. PATIENTS AND METHODS: Fifteen patients were studied. Six patients were in advanced refractory relapse, and induction therapy had failed in two patients. Patients with CLL or low-grade lymphoma received fludarabine 90 to 150 mg/m2 and cyclophosphamide 900 to 2,000 mg/m2. Patients with intermediate-grade lymphoma or in Richter's transformation received cisplatin 25 mg/m2 daily for 4 days; fludarabine 30 mg/m2; and cytarabine 500 mg/m2 daily for 2 days. Chemotherapy was followed by allogeneic stem-cell infusion from HLA-identical siblings. Patients with residual malignant cells or mixed chimerism could receive a donor lymphocyte infusion of 0.5 to 2 x 10(8) mononuclear cells/kg 2 to 3 months posttransplantation if graft-versus-host disease (GVHD) was not present. RESULTS: Eleven patients had engraftment of donor cells, and the remaining four patients promptly recovered autologous hematopoiesis. Eight of 11 patients achieved a complete response (CR). Five of six patients (83.3%) with chemosensitive disease continue to be alive compared with two of nine patients (22.2%) who had refractory or untested disease at the time of study entry (P = .04). CONCLUSION: These findings indicate the feasibility of allogeneic hematopoietic transplantation with a nonablative preparative regimen to produce engraftment and GVL against lymphoid malignancies. The ability to induce remissions with donor lymphocyte infusion in patients with CLL, Richter's, and low-grade and intermediate-grade lymphoma is direct evidence of GVL activity against these diseases. This approach appears to be most promising in patients with chemotherapy-responsive disease and low tumor burden.

Phase I trial of cyclosporine-induced autologous graft-versus-host disease in patients with multiple myeloma undergoing high-dose chemotherapy with autologous stem-cell rescue.

PURPOSE: To determine the feasibility and toxicity of inducing autologous graft-versus-host disease (GVHD) with cyclosporine in patients with multiple myeloma undergoing autologous stem-cell transplantation. PATIENTS AND METHODS: Fourteen multiple myeloma patients with a median age of 50 years (range, 41 to 63) were enrolled. The median time from diagnosis to transplant was 651 days (range, 229 to 3,353). Ten patients had primary refractory disease, two were in first remission, and two were responsive to salvage therapy. The preparative regimen consisted of thiotepa, busulfan, and cyclophosphamide. Cyclosporine was administered daily for 28 days after the stem-cell infusion, and the dose was adjusted to maintain whole-blood cyclosporine levels between 50 and 150 ng/dL in the first seven patients (low-level group) and between 150 and 300 ng/dL in the other seven patients (high-level group). RESULTS: All patients achieved neutrophil engraftment a median of 11 days after transplant. Four patients developed > or = grade 2 hepatic toxicity, six developed > or = grade 2 nephrotoxicity, and four developed reversible cardiac toxicity. Only one treatment-related death occurred. Cyclosporine was withheld in seven patients for a median of 6 days because of renal and/or liver dysfunction. One patient developed clinical skin GVHD, which responded to corticosteroid therapy. Six patients developed histologic evidence of GVHD without clinical signs of GVHD (subclinical GVHD). The incidence of clinical and subclinical GVHD was similar in both cyclosporine groups. Three of 11 patients assessable for response achieved remissions. Three patients experienced disease progression 80, 160, and 354 days after transplant. Ten patients are alive without progression between 56 and 444 days after transplant. CONCLUSION: Induction of autologous GVHD by posttransplant cyclosporine is feasible and well tolerated in patients with multiple myeloma.

Early detection of relapse by hypermetaphase fluorescence in situ hybridization after allogeneic bone marrow transplantation for chronic myeloid leukemia.

PURPOSE: Standard G-band cytogenetic analysis (CG) provides information on approximately 25 metaphases for monitoring the presence of Philadelphia chromosome positive (Ph+) cells in chronic myelogenous leukemia (CML) patients, making the detection of a low frequency of Ph+ cells problematic. The purpose of this study was to improve the detection of a low frequency of Ph+ cells. PATIENTS AND METHODS: We combined fluorescence in situ hybridization (FISH) with long-term colcemid exposure, capturing several hundred metaphases in bone marrow cultures (hypermetaphase FISH [HMF]). Using probes that identify Ph+ cells, HMF was compared with CG analysis in the follow-up evaluations of 51 patients with CML at various time points after allogeneic bone marrow transplant (BMT). RESULTS: Thirty-five patients never showed the presence of Ph+ cells by either method. In four patients, high frequencies of Ph+ cells were detected by both methods. In the remaining 12 patients, Ph+ cells were detected by HMF at time points after BMT when they were not detected by CG. In seven of the 12 patients, low but statistically significant frequencies of Ph+ cells (0.37% to 5.20%) were detected 3 months or later after BMT, and when no intervention was initiated, all seven patients later relapsed. Based on those data, an eighth patient with mixed chimerism and a similar HMF-detected Ph+ frequency (1.8% at 27 months after BMT) was reinfused with donor lymphocytes and achieved remission with 0% Ph+ cells studied by HMF (up to 50 months after BMT). Ph+ cells detected by HMF but not by CG less than 3 months after BMT disappeared on later examination in two of four patients. After detection of Ph+ cells by HMF only, the median time to cytogenetic progression (detection of Ph+ cells by CG) was 101 days. CONCLUSION: The results demonstrate the ability of HMF to detect low but clinically relevant levels of leukemic cells not detected by CG in transplant patients. The data indicate that HMF can detect low levels of Ph+ cells before standard cytogenetics at a time that may be useful in monitoring disease status and planning clinical interventions.

Allogeneic peripheral-blood progenitor-cell transplantation for poor-risk patients with metastatic breast cancer.

PURPOSE: To evaluate the feasibility of allogeneic peripheral-blood progenitor-cell (PBPC) transplantation and to assess graft-versus-tumor effects in patients with metastatic breast cancer. PATIENTS AND METHODS: Ten patients with metastatic breast cancer that involved the liver or bone marrow were treated with high-dose chemotherapy and allogeneic PBPC transplantation. The median age was 42 years (range, 29 to 55). The median number of metastatic sites was three (range, one to five). The conditioning regimen was cyclophosphamide (6,000 mg/m2), carmustine (BCNU; 450 mg/m2), and thiotepa (720 mg/m2) (CBT regimen). Patients received graft-versus-host disease (GVHD) prophylaxis using cyclosporine- or tacrolimus-based regimens. RESULTS: All patients had engraftment and hematologic recovery. Three patients developed grade > or = 2 acute GVHD and four patients had chronic GVHD. After transplantation, one patient was in complete remission (CR), five achieved a partial remission (PR), and four had stable disease (SD). In two patients, metastatic liver lesions regressed in association with skin GVHD after withdrawal of immunosuppressive therapies. The median follow-up time was 408 days (range, 53 to 605). The median progression-free survival duration was 238 days (range, 53 to 510). CONCLUSION: We conclude that allogeneic PBPC transplantation is a feasible procedure for patients with poor-risk metastatic breast cancer. The regression of tumor associated with GVHD provides suggestive clinical evidence that graft-versus-tumor effects may occur against breast cancer. Compared with autologous transplantation, allogeneic PBPC transplantation is associated with the additional risks of GVHD and related infections. Allogeneic transplantation should only be performed in the context of clinical trials and its ultimate role requires demonstration of improved progression-free survival.

Autologous bone marrow transplantation for acute myeloblastic leukemia in Europe: further evidence of the role of marrow purging by mafosfamide. European Co-operative Group for Bone Marrow Transplantation (EBMT).

Fifty-nine European teams have reported 919 autografts for the consolidation of acute myelocytic leukemia (AML) up to December 31, 1989. The distribution for autologous bone marrow transplantation (ABMT) was 671 in first complete remission (CR1) and 196 in CR2. Pretransplantation regimes were: total-body irradiation (TBI), 456; busulfan plus cyclophosphamide (BU-CY) 174; marrow purging with mafosfamide, 269 (corresponding to 26% of all patients in CR1 and 41% in CR2). Patients autografted in CR1 with no high risk factor (standard risk) had a leukemia-free survival (LFS) and relapse rate at 7 years of 48 +/- 2 and 41 +/- 3%, respectively. Of all the prognostic factors studied, only secondary leukemia was correlated with a poorer LFS (19 +/- 9% at 1 year) and a higher relapse rate (76 +/- 11%) (p less than 0.0001). For patients autografted in CR2, the LFS and relapse rate were 34 +/- 4 and 54 +/- 5%. With the restriction of a shorter follow-up, the results achieved with the BU-CY combinations (LFS and relapse rate at 3 years, CR1 47 +/- 6 and 45 +/- 7%; CR2, 37 +/- 9 and 50 +/- 10%) did not differ from those with TBI or other chemotherapy combinations. LFS and relapse rates were correlated with several pretransplant intervals: in CR1, patients reaching CR more rapidly (less than or equal to 40 days) had a better LFS (53 +/- 3 versus 42 +/- 3%; p = 0.03) and a lower relapse rate (46 +/- 3 versus 57 +/- 3%; p = 0.03). In patients autografted less than 3 months, 3-6 months and more than 6 months after CR, the LFS was 26 +/- 5, 49 +/- 3, and 55 +/- 4%, respectively, and the relapse rates 63 +/- 5, 38 +/- 3, and 36 +/- 4% (p less than 0.0001 for both). In CR2, patients autografted more than 18 months after the initial diagnosis had a better LFS (42 +/- 5 versus 24 +/- 5%; p less than 0.001) and a lower relapse rate (45 +/- 6 versus 65 +/- 6%; p less than 0.001). For those autografted less than 3 months, 3-6 months and more than 6 months after CR, the probability of LFS was 30 +/- 5, 30 +/- 7, and 50 +/- 9% (p = 0.06), respectively and the relapse rates 63 +/- 6, 50 +/- 8, and 36 +/- 8% (p = 0.01).(ABSTRACT TRUNCATED AT 400 WORDS)

Enhanced myelopoiesis in long-term cultures of human bone marrow pretreated with recombinant granulocyte-macrophage colony-stimulating factor.

Long-term bone marrow culture (LTBMC) for human hemopoiesis supports continuous proliferation and differentiation within the myeloid progenitor population by the formation of an adherent stromal monolayer. LTBMC represents the most suitable in vitro model for the study of regulatory mechanisms in human hemopoiesis. We investigated the effect of recombinant human granulocyte-macrophage colony-stimulating factor (rhuGM-CSF) on bone marrow of normal donors in LTBMC. The cells (2 x 10(6)/ml) were incubated with 100 ng/ml rhuGM-CSF for 24 h in culture medium supplemented with 10% fetal calf serum. After the preincubation, LTBMCs were started and maintained over a period of 10 weeks. After 1 week in culture we observed a statistically significant difference with a 1.5-fold higher number of nonadherent cells in the LTBMCs containing the bone marrow preincubated with rhuGM-CSF (p less than 0.05). This increase was due to an expansion of the mature myeloid cells. At the same time point the number of GM colony-forming units (CFU-GM)/ml in the LTBMCs with rhuGM-CSF-preincubated bone marrow was slightly increased compared to the controls without reaching a statistically significant level. We conclude that rhuGM-CSF at a saturation dose is a potent stimulator of in vitro myelopoiesis stem cell pool. This in vitro result is of relevance for the clinical use of rhuGM-CSF in patients undergoing bone marrow transplantation. The incubation of donor bone marrow prior to transplantation might be a new approach to facilitate the engraftment and to shorten the phase of pancytopenia.

Successful engraftment of blood derived normal hemopoietic stem cells in chronic myelogenous leukemia.

The ability of blood-derived stem cells to restore hemopoietic function was investigated in a patient with chronic myelogenous leukemia with bone marrow cells containing the Philadelphia chromosome marker (Ph1+). After treatment with high dose cyclophosphamide, 26.3 X 10(9) blood mononuclear leukocytes, among them 26.2 X 10(5) granulocyte/macrophage progenitor cells (CFUC), were harvested by means of 5 successive leukaphereses when the bone marrow cells had converted to Ph1--. When the patient entered the aggressive phase (blast crisis), myeloablative treatment with busulfan (16 mg/kg) and cyclophosphamide (200 mg/kg) was given, followed by transfusion of the cryopreserved blood leukocytes. Restoration of marrow and blood cellularity was completed about 20 days after this autologous blood stem cell transplantation (ABSCT). Marrow CTUC recovery was complete 2 weeks after ABSCT, and all karyotypes of the patient's marrow cells were free of the marker chromosome. The patient died of toxicity but with normal bone marrow cellularity. This report confirms the therapeutic usefulness of autologous blood-derived stem cells harvested in remission in restoring hemopoietic function after myeloablative treatment.

Albumin density gradient purification of canine hemopoietic blood stem cells (HBSC): long-term allogeneic engraftment without GVH-reaction.

Long-term repopulation of the blood-forming organs of dogs, conditioned by wholebody X-irradiation (1200 R midplane dose), was achieved by transfusion of cryopreserved allogeneic blood mononuclear cells (MNC) without causing graft-versus-host-reaction (GVH-R). Donor and recipient dogs were DL-A identical, MLC-negative, no siblings, non-related. The blood stem cells (CFUc) were procured by a 3- to 4-hour continuous-flow leukapheresis. To increase the CFUc concentration in the peripheral blood, dextran sulfate (DS) was administered intravenously beforehand. About 1 x 10(10) MNC, among them about 1 x 10(7) CFUc, were collected and further segregated using a discontinuous albumin density gradient. Less dense cells were to be found in the upper part of the gradient (fraction 2). These cells included most of the CFUc, enriched by a factor of between 275 and 1730 compared to their concentration in the peripheral blood beforehand. After cryopreservation, these cells, when transfused into lethally irradiated dogs, completely repopulated the marrow and lymph nodes, caused no GVH-R and allowed long-term survival. These dogs received no immunosuppressive therapy, either before or after transfusion. More dense MNC were to be found in fraction 3; their transfusion caused a severe GVH-R, followed quickly by death. Fraction 4 was rich in lymphocytes and poor in CFUc. The transfusion of these cells produced a selective plasma-cell hyperplasia of the lymph nodes but failed to repopulate permanently the marrow. The reappearance of the different cell lineages in the marrow and in the peripheral blood after conditioning and transfusion of these cells produced a selective plasma-cell hyperplasia of the lymph nodes but failed to repopulate permanently the marrow. The reappearance of the different cell lineages in the marrow and in the peripheral blood after conditioning and transfusion of the segregated MNC is described in detail.

Collection and cryopreservation of mononuclear blood leukocytes and of CFU-C in man.

For bone marrow reconstitution after hemopoietic failure as a consequence of the action of a variety of etiological factors, hemopoietic stem cells are needed. These have been derived in the past mainly from bone marrow. This report describes studies and their results that indicate that granulocytic progenitor cells, measured in cell culture systems as "colony forming units in culture - CFU-C", can be collected in large quantities from the peripheral blood of human blood donors by continuous flow leukapheresis. They can be stored at ultra-low temperatures. Their recovery rate after thawing and washing is better than 85%. In a canine model, evidence was obtained that the presence of CFU-C in a suspension of mononuclear blood leukocytes is also indicative for the presence of pluripotent hemopoietic stem-cells. Therefore it is suggested that stem cells can also be collected from human blood as an alternative source for bone marrow reconstitution.

A mathematical model of haemopoiesis as exemplified by CD34 cell mobilization into the peripheral blood.

A mathematical model for the kinetics of haemopoietic cells, including CD34+cells, is proposed. This minimal model reflects the known kinetics of haemopoietic progenitor cells, including peripheral blood CD34+ cells, white blood cells and platelets, in the presence of granulocyte colony-stimulating factor. Reproducing known perturbations within this system, subjected to granulocyte colony-stimulating factor treatment and apheresis of peripheral blood progenitor cells (CD34+ cells) in healthy individuals allows validation of the model. Predictions are made with this model for reducing the length of time with neutropenia after high-dose chemotherapy. Results based on this model indicate that myelosuppressive treatment together with infusion of CD34+ peripheral blood progenitor cells favours a faster recovery of the haemopoietic system than with granulocyte colony-stimulating factor alone. Additionally, it predicts that infusion of white blood cells and platelets can relieve the symptoms of neutropenia and thrombocytopenia, respectively, without drastically hindering the haemopoietic recovery period after high dose chemotherapy.

Peripheral Blood Stem Cells: A Novel Source for Allogeneic Transplantation.

Cytokine-mobilized peripheral blood stem cells (PBSCs) are increasingly viewed as a promising alternative to bone marrow (BM)-derived stem cells for allografting in patients with hematologic malignancies. Preliminary results seem to indicate several potential advantages of this approach, such as: A) a more "donor-friendly" and possibly safer stem cell collection procedure; B) the procurement of a significantly larger number of progenitor cells (allowing for graft engineering opportunities); C) a faster hematopoietic engraftment including immunologic reconstitution, and D) comparable rates of acute graft-versus-host disease. Although the superiority of this approach over the traditional BM allografting has not been clearly demonstrated thus far in a randomized trial and many open issues remain, experience is accumulating rapidly, and major transplant centers worldwide seem to have endorsed this procedure. The acceptance of the peripheral blood as the primary source of stem cells for hematopoietic reconstitution in the allogeneic setting is likely to have a profound impact in areas such as graft-versus-leukemia/tumor effect, unrelated donor registries, and transplants. In the following, currently available information on blood stem cell harvesting and allografting is reviewed with the particular focus on donor safety.

Allogeneic transplantation for advanced leukemia: improved short-term outcome with blood stem cell grafts and tacrolimus.

We have evaluated the use of blood stem cell grafts for rapid hematopoietic recovery and tacrolimus (FK506) as GVHD prophylaxis to reduce early mortality after allogeneic transplantation. Eighty-five adults with advanced leukemia received high-dose thiotepa, busulfan, and cyclophosphamide as a preparative regimen in a prospective Phase II study. All donors were HLA-matched and related. Marrow (BMT) was used for 44 patients and filgrastim-mobilized blood stem cells (SCT) for 41 patients. GVHD prophylaxis consisted of cyclosporine (CsA) or FK506 with methotrexate (MTX) or methylprednisolone (MP). The median time to neutrophil recovery was earlier after SCT than after BMT (day 10 vs. 17, P<0.001), but this was due to the selective use of MTX only in the BMT patients. The risk of grades 2-4 GVHD was lower with FK506 than with CsA (16% vs. 45%, P=0.02) and was the same for SCT recipients as for BMT recipients (33% vs. 34%). Regimen-related toxicity was significantly lower after SCT than after BMT but did not differ between the FK506 and CsA patients. In comparison with those receiving the standard transplant (BMT with CsA and MTX), only the SCT recipients using FK506 and MP had a significantly higher survival at day 180 posttransplant (84% vs. 53%, P=0.014). In multivariate analyses, use of FK506 was associated with a lower risk of treatment-related mortality and a higher survival at day 180, while the diagnosis of acute lymphoblastic leukemia was associated with a higher risk of treatment-related mortality. These data suggest that the use of blood stem cell grafts and FK506 can reduce the early mortality after allogeneic transplantation for advanced leukemia.

Adult stem cells and tissue repair.

Recently, adult stem cells originating from bone marrow or peripheral blood have been suggested to contribute to repair and genesis of cells specific for liver, cardiac and skeletal muscle, gut, and brain tissue. The mechanism involved has been termed transdifferentiation, although other explanations including cell fusion have been postulated. Using adult stem cells to generate or repair solid organ tissue obviates the immunologic, ethical, and teratogenic issues that accompany embryonic stem cells.

The evolution of clinical peripheral blood stem cell transplantation.

Our growing physiological understanding of hematopoietic progenitor cells has led to the clinical use of circulating progenitor cells, including stem cells, for either reconstitution of hematopoietic function, up to the transduction of functional genes into a self-renewing cell system. In the following, an attempt has been made to recollect the major steps in the evolution of clinical blood stem transplantation, from the morphological description of small lymphocytes circulating in the blood up to somatic gene therapy covering a time period of 87 years.

Allogeneic peripheral blood stem cell transplantation for active hemophagocytic lymphohistiocytosis.

Hemophagocytic lymphohistiocytosis (HLH) is a lethal disorder of immune dysregulation. Successful allogeneic BMT is the only therapy that has produced long-term disease-free survival. However, for patients with active HLH the outcome of BMT remains poor when compared with those transplanted in remission. We describe a patient with active, recurrent HLH treated with high-dose chemotherapy and related allogeneic peripheral blood stem cell (PBSC) transplantation. Hematologic recovery was rapid and the post-transplant course was uncomplicated. The patient is alive and well 2 1/2 years after transplant. Allogeneic PBSC transplantation may deserve further evaluation as an alternative source of stem cells for transplantation in patients with active HLH.

Blood stem cell procurement: donor safety issues.

Allogeneic transplantation of rhG-CSF-mobilized peripheral blood stem cells (PBSCs) is now being increasingly performed, but safety considerations for hematologically normal PBSC donors have not been fully addressed. Experience in this area is rapidly accumulating, however, and on the basis of currently available data, a consensus is gradually emerging on several issues: (1) rhG-CSF treatment and PBSC collection seem to have an acceptable short-term safety profile in normal donors. There is a need for continued safety monitoring, however. (2) rhG-CSF doses up to 10 microg/kg/day show a consistent dose-response relationship with the mobilization (and collection) of CD34+ progenitor cells, and this dose is acceptable for routine clinical use. Whether higher doses are superior (or cost-effective) remains to be determined, and they may produce more severe side-effects. The potential risks of marked leukocytosis (arbitrarily defined as a leukocyte count of more than 70 x 10(9)/l) have been a concern, and rhG-CSF dose reduction is performed by many centers to maintain leukocyte counts below this level. (3) Transient post-donation cytopenias, involving granulocytes, lymphocytes and platelets, may occur and are at least partly related to the leukapheresis procedure. These are generally asymptomatic and self-limited; follow-up blood counts are not necessarily required. Reinfusion of autologous platelet-rich plasma should be considered for donors with expected post-donation thrombocytopenia (platelet count <80-100 x 10(9)/l). (4) Donors should meet the eligibility criteria which apply to donors of apheresis platelets, with the exception that pediatric (as well as elderly) donors may also be considered. There is insufficient information at this time to clearly establish definite contraindications for PBSC collection in a hematologically normal donor. Potential contraindications include the presence of inflammatory, autoimmune or rheumatologic disorders, as well as atherosclerotic or cerebrovascular disease. (5) The creation of an International PBSC Donor Registry is desirable to facilitate monitoring the long-term effects of the procedure. Individual institutions or donor centers are encouraged to establish their own PBSC donor follow-up system, preferably with a standardized approach to data collection.