Autologous transplantation in chronic myeloid leukaemia using peripheral blood stem cells

Forty-three patients with chronic myeloid leukaemia in first chronic phase were recruited to study intensive chemotherapy (idarubicin plus cytarabine; IdAC) followed by collection of peripheral blood stem cells (PBSC) in the recovery phase. PBSC autografting was performed on 32 patients. One patient died during mobilization and three died following autograft. All procedural deaths occurred in patients who received IdAc more than a year from diagnosis. Nine further patients died, eight following progression of CML. 72% of transplanted patients showed a major cytogenetic response but most cases have returned to Philadelphia-positive haemopoiesis. 62% of autografted patients remain alive (median survival from diagnosis 52 months). Four of the 11 patients who did not receive a transplant remain in chronic phase.     

High-dose chemotherapy and hematopoietic stem cell rescue in patients with relapsed Hodgkin's disease

Summary Fifty-one consecutive patients with Hodgkin's disease (HD) have been treated with high-dose chemotherapy (HDT) and transplantation of autologous bone marrow (BM) (n=44), autologous BM plus peripheral blood stem cells (PBSC) (n=2), PBSC (n=1), syngeneic (n=1), or allogeneic BM (n=3). All patients had received standard salvage chemotherapy prior to HDT and were classified as sensitive (n=33) or resistant (n=17) to this treatment; one patient was in untreated relapse prior to BMT. The preparative regimens for patients receiving autologous BM and/or PBSC consisted of cyclophosphamide, VP 16, and BCNU (CVB) (n=44) or BCNU, etoposide, ara-C, and melphalan (BEAM) (n=3). The patients receiving allogeneic transplants were treated with the CVB regimen (n=2) or busulfan (16 mg/kg body wt.) and cyclophosphamide (200 mg/kg body wt.). With a median follow-up of 12 months, overall survival for 44 patients grafted with autologous BM is 61%±9%, progression-free survival for patients with sensitive disease is 44%±11%; no patient with resistant relapse survived beyond 1 year post transplant. Two of three patients grafted with allogeneic BM still survive 15 and 24 months after BMT with Karnofsky performance scores of 70% and 100%, respectively. The main toxicity encountered with the CVB regimen was interstitial pneumonia (IP), seen in four of 15 patients (27%) receiving 600 mg/m² of BCNU. Three of these patients have died. The results show that HDT followed by hematopoietic stem cell rescue may effectively salvage an important fraction of patients with relapsed HD who respond to standard chemotherapy. The same approach is largely unsuccessful in patients with proven refractoriness to standard chemotherapy. Whether HDT followed by BMT or PBSC support is superior to intensive chemotherapy without stem cell support can be answered only by a prospectively randomized trial.     

Intensive radio-chemotherapy with peripheral blood stem cell transplantation in young patients with chronic lymphocytic leukemia.

Two patients with previously treated CLL received autologous PBSC transplantation after total body irradiation and high-dose chemotherapy. Before intensification, a partial marrow response had been obtained in both patients, with disappearance of peripheral blood involvement as shown by immunophenotypic assessment using fludarabine. PBSC collection was performed after a single course of high-dose cyclophosphamide followed by GM-CSF administration. One patient failed to reconstitute normal hematopoiesis and died 3 months post-transplant. The other is in continuous complete remission 12 months after intensification. This strategy in young patients with poor prognosis CLL warrants further investigation.     

Autografts with peripheral blood stem cells

This paper reports a clinical and laboratory experience of peripheral blood stem cell (PBSC) autografts at a single institute. Twenty-eight children with various types of cancer underwent a total of 90 leukaphereses to collect PBSC and 17 of them subsequently received marrow-ablative therapy and PBSC autografts. We found that frozen-thawed progenitor dose is important in determining the rate of hematopoietic recovery after transplantation; in 11 patients who received more than 1 x 10(5) CFU-GM/kg, the granulocyte count reached to 0.5 x 10(9)/L in two weeks. With conditioning chemotherapy without total body irradiation, 6 of 14 patients with high-risk acute leukemia or non-Hodgkin's lymphoma have survived disease-free 3 to 25 months posttransplant. This approach may have a potential to induce prolonged remission-interval and ultimate cure.     

Pegfilgrastim effectively mobilizes PBSC in a poor mobilizer multiple myeloma patient

Studies performed on mice and healthy human volunteers have shown that a single dose of pegfilgrastim (Peg-GCSF) is effective in stimulating peripheral blood stem cells (PBSC) mobilization. This prompted us to try the stimulation with pegfilgrastim in a patient previously non-mobilizing with a combination of chemotherapy and filgrastim. In December 2003, a 65-yr-old man was diagnosed as having stage III A IgG/k multiple myeloma. He received three courses of polichemotherapy (DC-IE) obtaining a stable response. Afterwards, the patient was treated with high-dose cyclophosphamide (CPM; 7 g/sqm) plus daily 10 mcg/kg filgrastim in order to mobilize PBSC, without success. After 2 months off therapy, the disease progressed and the patient received alternate cycles VAD (vincristine, dexamethasone, adriblastine)/high-dose dexamethasone. A second attempt to mobilize PBSC, using daily 10 mcg/kg filgrastim after the second and third VAD cycle, failed. In a further attempt to mobilize PBSC, we administered a single dose of 12 mg pegfilgrastim on day 5 after a fourth VAD course. Daily evaluation of circulatory CD34+ cells was started from day 8 after the end of chemotherapy. On day +10 postchemotherapy the CD34+ cell count was 24/microL and two aphaeresis were performed, harvesting 1.6 x 10(6) and 0.89 x 10(6) CD34+ cells/kg respectively (total 2.49 x 10(6) cells/kg). The only side effect was moderate skeletal pain. The patient underwent successful transplantation. The median times necessary to recover 0.5 x 10(9) PMN/L and 20 x 10(9) platelets/L after PBSC reinfusion were 9 and 12 d respectively. The patient did not need red blood cell or platelet transfusions. He experienced a sustained engraftment and maintains complete remission 9 months after the reinfusion. In conclusion, a single dose of pegfilgrastim was able to mobilize a sufficient number of CD34+ in a multiple myeloma patient not responsive to two previous attempts with high or standard dose chemotherapy followed by filgrastim. This approach, if confirmed on larger series and other diseases, could open new opportunities in stem cell mobilization for poor or non-mobilizers.     

Outcome of peripheral blood stem cell mobilization in advanced phases of CML is dependent on the type of chemotherapy applied

 High-dose chemotherapy with autologous transplantation of in vivo purged PBSC is a novel investigational approach to treating chronic myelogenous leukemia (CML) patients not responsive to conventional therapy with interferon-α (IFN-α) and not eligible for allogeneic transplantation. PBSC mobilization using either '5+2/7+3'-type chemotherapy or 'mini-ICE/ICE' chemotherapy was investigated in 43 patients with advanced phases of Philadelphia (Ph)-positive CML. Thirty patients were in late chronic phase (>12 months post diagnosis) and 13 patients in accelerated phase (AP) or blast crisis (BC). Contamination with Ph-positive cells was evaluated in harvests from 37/43 patients. The outcome of PBSC mobilization was dependent on the type of chemotherapy administered: a complete or major cytogenetic response (<35% Ph-positive metaphases) in leukapheresis collections was obtained in ten of 15 patients treated with 'mini-ICE/ICE' but in only three of 28 patients treated with '5+2/7+3' chemotherapy. One patient (1/43) in blast crisis died during mobilization therapy (2%). Twenty-five patients underwent PBSC transplantation and all of them engrafted successfully. Transplantation-related mortality was 0%. The data show that in advanced phases of CML the chance of harvesting Ph-negative peripheral blood stem cells depends on the type of chemotherapy used for mobilization. Received: February 6, 1998 / Accepted: May 19, 1998     

High-dose BCNU therapy with autologous bone marrow infusion: preliminary observations.

Nine patients with solid malignancies and extensive prior treatment received high-dose BCNU therapy (600--750 mg/m2) with autologous bone marrow support; following this treatment hematopoietic recovery was studied. The only significant nonhematopoietic toxicity was a probable case of BCNU-induced pulmonary toxicity in a patient who had received massive amounts of prior chemotherapy and chest irradiation. The marrow aspirations prior to cryopreservations had revealed a hypoplastic marrow in four of nine patients. Despite using marrow exposed to prior chemotherapy, neutropenia beyond Day 40 after BCNU therapy was not observed in any patient. One patient did not develop neutropenia of less than 1.5 X 10(9) cells/liter and five patients did not develop neutropenia of less than 0.5 X 10(9) cells/liter. A partial response was observed in one patient and less than partial responses were observed in two other patients. Autologous bone marrow infusion may modify the neutropenia of high-dose BCNU therapy.     

Cyclophosphamide, etoposide and carboplatine plus non-cryopreserved autologous peripheral blood stem cell transplantation rescue for patients with refractory or relapsed non-Hodgkin's lymphomas

A simplified schedule of high-dose chemotherapy consisting of cyclophosphamide (60 mg/kg/day for 2 days), etoposide (15 mg/kg/day for 2 days) and carboplatine (400 mg/m(2)/day for 2 days), together with autologous non-cryopreserved peripheral blood stem cells was used for treatment of relapsed (29 patients) and refractory (three patients) patients with non-Hodgkin's lymphoma (NHL). The use of such granulocyte colony-stimulating factor (G-CSF)-mobilized peripheral blood stem cells (PBSC) after high-dose myeloablative therapy resulted in a rapid, complete and sustained hematopoietic recovery. The median time to achieve an absolute neutrophil count greater than 0.5 x 10(9)/l was 12 days (range 8-17 days). The median time to self-sustained platelet count greater than 20 x 10(9)/l was 14 days (range 7-19 days). Fifteen of the 32 patients (49%) were alive and disease free at a median follow-up of 18 months (range 10-96 months) for all surviving patients. The estimated 2-year overall survival (OS) and disease free survival (DFS) for all patients were 50 and 43%, respectively. Twelve patients died of relapse or progressive disease, two patients died of infection and one patient died of cardiac cause. The median time to relapse was 12 months (5-27) from PBSC infusion. High-dose chemotherapy with short-duration chemotherapy and non-cryopreserved bone marrow (BM) is an effective and safe treatment modality for patients with relapsed or resistant NHL.     

Non-haematological toxicity limiting the application of sequential high dose chemotherapy in patients with advanced breast cancer.

A programme of repeated high dose chemotherapy for advanced breast cancer was developed using (1) cyclophosphamide 4 g/m2 followed by autologous peripheral blood stem cell (PBSC) collection; (2) three cycles of conventional dose chemotherapy; (3) high dose cyclophosphamide, cisplatin, and carmustine with PBSC rescue; and (4) high dose etoposide and melphalan with PBSC rescue. Fifteen eligible patients had advanced poor prognosis breast cancer either at initial diagnosis (one patient) or at relapse (14 patients). During the course of the protocol, there were three treatment related deaths, two patient withdrawals due to debilitating toxicity, five patient withdrawals due to disease progression, and one patient withdrawal due to inadequate collection of PBSC. The remaining four patients did not complete the planned protocol as the programme was terminated because of the unacceptable morbidity and mortality. They were treated with an alternative high dose chemotherapy protocol which was well tolerated. This study highlights the significant problems associated with a complex sequential high dose chemotherapy regimen. Cyclophosphamide mobilized PBSC infused following high dose chemotherapy enables rapid haematological recovery. However the non-haematological toxicity following high dose chemotherapy regimens is often severe and may limit the application of certain sequential high dose chemotherapy combinations in patients with breast cancer.     

Individually adjusted prophylactic donor lymphocyte infusions after CD34-selected allogeneic peripheral blood stem cell transplantation.

T cell depletion of the graft increases graft failure and relapse rate in allogeneic PBSC transplantation. Delayed lymphocyte add-back after T cell-depleted transplants might prevent these complications. We present 22 consecutive allogeneic PBSC transplants from related histocompatible donors with positive selection of CD34+ cells. Recipients received prophylactic donor lymphocyte infusions (DLI) depending on their risk of relapse and of developing GVHD. Patients were considered at high risk of relapse with AML > first CR, ALL > second CR, and CML in accelerated or blastic phase. Patients were considered at high risk of developing GVHD if older than 35 years, or with a donor sensitized through previous pregnancy or blood transfusion. Patients at high risk of relapse and low risk of GVHD were scheduled to receive three DLI. Patients at low risk of relapse and high risk of GVHD did not receive DLI. The remaining patients were scheduled to receive two DLI. The DLI were administered on days +28 (2 x 10(5)/kg), +60 (2 x 10(5)/kg) and +90 (2 x 10(6)/kg) after transplant. G-CSF mobilized peripheral stem cells from healthy donors were positively selected by an immunomagnetic method. The mean CD34+ cells and CD3+ cells infused were 4.4 x 10(6)(range 1.9-10.6) and 0.085 x 10(5) (range 0.01-0.67). Cyclosporin A was given to prevent GVHD. All the patients engrafted. Twenty-two prophylactic DLI were performed in 12 patients: seven developed acute GVHD (one case grade III-IV) and none presented pancytopenia. At a mean follow-up of 585 days (range 89-1103), 14 patients were alive in CR, one patient was alive in relapse, four patients had died of relapse and three had died of transplant-related complication. Individually adjusted prophylactic DLI at the doses we used with an escalating schedule allowed an acceptable GVHD rate and a good engraftment of donor hematopoiesis.     

Collection and use of peripheral blood stem cells in very small children.

Collections of peripheral blood stem cells (PBSC) from children weighing less than 25 kg have been limited by concern about citrate toxicity. We developed a modified collection technique on the Fenwal CS3000 blood cell separator and used it in three children weighing 8.3, 20 and 24 kg with neuroblastoma involving the marrow. The saline prime was discarded as a mixture of 250 ml red cells, 100 ml fresh frozen plasma, and 100 ml 5% albumin was run into the separator. Heparin (1500 units/h) was used to supplement ACD, which was infused at a low rate (1:25-1:32 vs blood, vs the usual 1:13). No serious difficulties were encountered during or after the collections. A total of 5.7, 4.8 and 6.4 x 10(8) mononuclear cells/kg were collected in six procedures per patient. After cell cryopreservation and patient preparation using high-dose chemotherapy, the cells were thawed in 37 degrees C saline and infused without incident. Hematopoietic recovery was observed, and one of the patients remains in clinical remission after 11 months of follow-up. The addition to previously developed procedures of the use of partial albumin prime, low citrate anticoagulation, and heparin allows convenient and safe collection of PBSC in extremely small children, and these PBSC are effective.     

High-dose cytarabine for the treatment of blastic phase chronic myelogenous leukemia

High-dose cytarabine chemotherapy regimens were given to 22 patients for the treatment of blastic phase chronic myelogenous leukemia. Bone marrow aplasia occurred in 21 of these patients; in one patient the marrow was not cleared of blasts. In five patients (26%), blastic phase promptly recurred. Eight patients (37%) died of infection or hemorrhage during the period of marrow aplasia before bone marrow recovery. Seven patients achieved complete remission and one achieved partial remission, but the duration of the remission was brief [median, 98 days (range, 52-345)]. One patient received consolidation therapy with an additional course of high-dose cytarabine and maintained remission for 345 days. These results suggest that alternative approaches to the treatment need to be explored.     

Contamination of peripheral blood stem cell harvests by circulating neuroblastoma cells

Peripheral blood stem cells (PBSC) are being used as one alternative to autologous marrow rescue for patients with neuroblastoma and other solid malignancies. Some physicians prefer use of PBSC because less risk of tumor contamination is believed to exist. This hypothesis was evaluated by immunocytologic analysis of blood samples and concurrently drawn bone marrow (BM) samples and of PBSC harvests obtained from 31 patients with disseminated neuroblastoma. We found circulating neoplastic cells in 75% of specimens analyzed at diagnosis, in 36% during therapy, and in 14% of PBSC harvests. Tumor cells in blood obtained during therapy did not appear until 3 months after the time of diagnosis. Clearance of circulating neuroblastoma cells was documented after two courses of induction chemotherapy. Six of 13 patients with minimal or no BM disease had positive blood specimens. We conclude that substantial risk of tumor contamination of PB harvests exists and recommend that induction chemotherapy be administered before hematopoietic progenitor cells are collected from blood.     

Delayed introduction of G-CSF after chemotherapy does not affect peripheral blood stem cell yield and engraftment kinetics in children with high-risk malignancies: retrospective study of 45 cases

We retrospectively compared the effects of two time points of G-CSF (Filgrastim) introduction for PBSC mobilization in 45 children with different malignancies. Seventeen patients received the first G-CSF dose on day 2 or 3 following chemotherapy (group 1). Twenty-eight patients received a "flexible" G-CSF injection schedule when the G-GSF was started at the time of the first platelet count rise during post-chemotherapy recovery phase (group 2). Leukapheresis was performed when WBC recovery reached >2.0 x 10(9)/l or if the peripheral blood CD34(+) cell level was >0.01 x 10(9)/l. A median of 2 (1-4) leukapheresis procedures was performed in both groups to yield a median of 4.2 and 6.1 x 10(6) CD34(+) cells/kg in groups 1 and 2, respectively, which was generally sufficient for auto-transplantation. The proportion of patients with a failure of PBSC collection was similar and G-CSF consumption estimated through the total cycle dose was 2.3 times less in group 2 without increasing infectious risks. The short-term hematological recovery and the early post-transplant course were similar in the two groups. Delayed introduction of G-CSF after chemotherapy allowed PBSC harvest equivalent to that obtained after early G-CSF introduction. This approach could be an interesting alternative in PBSC mobilization but should be assessed by a prospective controlled study.     

Treatment of relapsing leukemia after allogeneic blood stem cell transplantation by using dose-reduced conditioning followed by donor blood stem cells and GM-CSF

Ten patients with high-risk acute myeloid leukemia (AML), chronic myeloid leukemia (CML), and myelodysplastic syndrome (MDS) relapsing early (< 1 year, n = 8) or late (> or = 1 year, n = 2) after allogeneic transplantation were treated with cytoreductive chemotherapy followed by unmanipulated peripheral blood stem cell transplantation (PBSCT) from related (n = 3) and unrelated donors (n = 7). In order to enhance the graft-versus-leukemia effect, patients received no graft-versus-host disease (GVHD) prophylaxis and granulocyte-macrophage colony-stimulating factor (GM-CSF) was given at a dose of 60 micrograms/m2 after transplant. Acute GVHD grade I-IV was seen in all patients. Eight out of ten patients achieved complete remission: one out of two patients with AML and late relapse is in good condition with limited chronic GVHD more than 1 year after the second PBSCT. The other patient died on day +171 after the second PBSCT from cerebral aspergillosis. One patient with blastic phase CML achieved molecular remission but died +330 days after the second PBSCT because of intracranial bleeding. Of the remaining five patients, three died of infectious complications on days +36, +70, and +27, one patient died with extramedullary relapse on day +35, and one from multi-organ failure in association with acute GVHD on day +32 after the second PBSCT. Two out of ten showed progressive disease and died on days +30 and +90, respectively. Although several patients achieved complete remission, the high risk of GVHD and treatment-related mortality should be kept in mind, especially when a second transplant is considered during a period of less than 12 months after the first procedure. Monitoring of minimal residual disease might predict relapse thus preventing high doses of cytotoxic drugs for reconditioning. The potential of GM-CSF to enhance the graft-versus-leukemia reactivity after cytoreductive therapy for allogeneic transplantation warrants further investigation.     

Autografting for patients with CML in chronic phase: an update

Between 1984 and 1992, 21 patients with chronic myeloid leukaemia (CML) in chronic phase (CP) were treated with high-dose chemotherapy (or chemoradiotherapy) followed by autografting with unmanipulated peripheral blood stem cells (PBSC). 12 of these patients survive at a median of 82 months from the time of autografting (range 9–105 months). Nine patients died, six of leukaemia in transformation and three from other causes. Survival of these 21 autograft patients was compared to that of 636 age-matched controls on the Medical Research Council's (MRC) data base, who had been treated with conventional chemotherapy over the same period. Autografted patients had a significantly longer survival at 5 years post autograft than chemotherapy patients (56% v 28%) even after appropriate allowance for time at risk before autograft (Mantel-Byar, 2 P = 0·003). There was no difference in survival whether autografting was performed early in the disease or later or whether the PBSC had been harvested soon after diagnosis or later. If the benefits of autografting in chronic phase seen in this non-randomized series can be confirmed in a randomized study, autografting might be the treatment of choice for younger CML patients who do not have suitable donors for allogeneic transplant.     

Factors affecting duration of survival after onset of blastic transformation of chronic myeloid leukemia

We analyzed factors having an impact on response to treatment and survival in 78 consecutive patients with chronic myeloid leukemia (CML) in blastic transformation (BT) referred to the Hammersmith Hospital from January 1995 to December 2000. BT was defined as the presence of at least 30% blasts in blood or marrow or extramedullary blastic deposits. Immunophenotyping of blasts showed 57 myeloid, 19 lymphoid, and 2 biphenotypic. The median age of the patients was 39.1 years (range, 11.3-73.4 years), with 55 males and 23 females. The median survival for all patients after onset of BT was 8.2 months (95% CI, 6.4-10). Patients in lymphoid BT survived longer than those in myeloid BT (median, 11.2 months versus 6.9 months, P =.052). Initial treatment varied; 41 patients received cytotoxic drugs, 8 underwent allogeneic or autologous transplantation procedures, 21 received STI571 (imatinib mesylate, Gleevec), 1 received radiotherapy, and 7 received no therapy. Of the 25 (32%) patients who achieved a "second chronic phase" with first therapy, 6 of 21 (29%) were treated with STI571 and 19 of 50 (38%) were treated with chemotherapy, transplantation, or radiotherapy. Patients who achieved a second chronic phase survived longer than those who did not (median time from onset of BT 12.0 months versus 6.3 months, P =.0004). In multivariate analysis the finding of more than 50% blast cells in the blood and the presence of cytogenetic progression were independent adverse prognostic variables for survival. We conclude that survival after onset of BT has improved in recent years but is still unsatisfactory. We speculate that the combined use of STI571 with cytotoxic drugs may offer additional benefit.     

ICE (ifosfamide, carboplatin, etoposide) as second-line chemotherapy in relapsed or primary progressive aggressive lymphoma--the Nordic Lymphoma Group experience

OBJECTIVE: To evaluate ICE (ifosfamide, carboplatin, etoposide) as second-line chemotherapy in relapsed or primary progressive aggressive lymphoma, in terms of objective response rate (ORR) and peripheral blood stem cell (PBSC) harvest mobilization rate. PATIENT POPULATION: A total of 40 patients were included, with a median age of 57 yr. The major histopathological subgroup was diffuse large B-cell lymphoma (n = 27). The indication for ICE was relapse in 23 patients, primary progressive disease in 11, transformation in four and adjuvant primary chemotherapy in one patient. RESULTS: After three cycles of ICE, the ORR was 59%. Among patients with primary progressive disease, ORR was 36% (four of 11). A PBSC harvest after ICE could be performed in 11 of 20 patients, and was sufficient for stem cell rescue in 10 of 20. The median number of collected CD34+ cells was 3.6 x 10(6) (range 1.4-12.5). In six of 10 patients, an adequate PBSC harvest could be performed with a second mobilization regimen. CONCLUSION: In this patient population, the rate of response to ICE was comparable with other second-line regimens used in aggressive lymphoma. The rate of harvest failure (45%) was disappointingly high, compared with previous reports, possibly because of patient selection or differences in granulocyte-colony stimulating factor (G-CSF) dosage.     

Supplemental peripheral blood stem cells to decrease marrow rejection in adult patients with severe aplastic anemia

Twenty-two multi-transfused patients with a long duration of severe aplastic anemia (SAA) received a transplant from an HLA-matched donor after cyclophosphamide (CY) plus antithymocyte globulin plus procarbazine using CD34(+) enriched blood stem cells + fresh marrow. Peripheral blood stem cells (PBSC) were collected on days 5 and 6 of G-CSF (10 microg/kg/day), and T cells were depleted using an immunoadsorption column (n = 15) or magnetic cell sorting (n = 7). Marrow harvesting was performed 48 hr after the last leukapheresis. Two patients (9.1%) that developed graft failure had a successful engraftment again using unpurged PBSC. Median time to neutrophils > or = 0.5 x 10(9)/l and platelets > or = 20 x 10(9)/l without platelet transfusions were 12 days and 17 days, respectively. Acute graft-versus-host disease (GVHD) grade II occurred in four of 22 patients. No patient developed grade III or IV acute GVHD. Four of the evaluable 21 patients had chronic GVHD. One patient developed extensive disease. Three patients (13.6%) died from CY-induced heart failure, extensive-type chronic GVHD, and sepsis of unknown cause. The Kaplan-Meier estimate of survival was 83.9% (95% CI, 70.1-95.2%) with a median follow-up duration of 33.5 (6-44) months. CD34(+)-enriched PBSC in combination with unmanipulated marrow seem to play a role in overcoming the sensitization to histocompatibility antigens without an apparent increase in GVHD. The stem cell component therapy may be feasible for the high-risk SAA adult patients.