No difference in graft-versus-host disease, relapse, and survival comparing peripheral stem cells to bone marrow using unrelated donors

Transplantation of hematopoietic stem cells from the peripheral blood

Hematopoietic stem cells can be collected from the peripheral blood. These hematopoietic stem cells (HSC), or better progenitor cells, are mostly expressed as the percentage of cells than react with CD34 antibodies or that form colonies in semi-solid medium (CFU-GM). Under steady-state conditions the number of HSC is much lower in peripheral blood than in bone marrow. Mobilization with chemotherapy and/or growth factors may lead to a concentration of HSC in the peripheral blood that equals or exceeds the concentration in bone marrow. Transplantation of HSC from the peripheral blood results in faster hematologic recovery than HSC from bone marrow. This decreases the risk of infection and the need for blood-product support. For autologous stem-cell transplantation (SCT), the use of peripheral blood cells has completely replaced the use of bone marrow. For allogeneic SCT, on the other hand, the situation is more complex. Since peripheral blood contains more T-lymphocytes than bone marrow, the use of HSC from the peripheral blood increases the risk of graft-versus-host disease after allogeneic SCT. For patients with goodrisk leukemia, bone marrow is still preferred, but for patients with high-risk disease, peripheral blood SCT has become the therapy of choice.

A Comparison of Nonmyeloablative and Reduced-Intensity Conditioning for Allogeneic Stem-Cell Transplantation

BACKGROUND

Nonmyeloablative (NM) conditioning and reduced-intensity conditioning (RIC) are increasingly used for allogeneic hematopoietic stem-cell transplantation. Such regimens have not been compared.

METHODS

The primary endpoint was graft-versus-host disease (GVHD). Secondary endpoints included transfusions, engraftment, and transplant-related mortality (TRM). NM conditioning (n=24) consisted of fludarabine and 2-Gy total-body irradiation followed by immunosuppression with cyclosporine A (CsA) combined with mycophenolate mofetil (MMF). The RIC (n=34) protocol consisted of fludarabine combined with busulfan or cyclophosphamide, antithymocyte globulin, and posttransplant immunosuppression CsA plus methotrexate. Diagnoses included hematologic malignancies and solid tumors. Donors were 34 human leukocyte antigen-identical siblings and 24 unrelated donors. Chimerism was analyzed by polymerase chain reaction of minisatellites.

RESULTS

Graft failure occurred in 6 of 24 in the NM group and in 1 of 34 in the RIC group, which was a significant difference (odds ratio [OR], 22.6; P=0.02). The NM group also had less leukopenia and required fewer erythrocyte and platelet transfusions than the RIC group. The time to and proportion of CD3, CD19, and CD45 donor chimerism were similar in both groups. The cumulative incidence of grades II to IV acute GVHD was higher in the NM group (59% vs. 12%; OR, 26.9; P<0.001), but we found no difference in the cumulative incidence of chronic GVHD (41% vs. 61%). TRM was 42% in the NM group and 20% in the RIC patients (relative hazard, 11.6; P=0.03).

CONCLUSIONS

NM conditioning with posttransplant immunosuppression using CsA and MMF resulted in less leukopenia and fewer transfusions, but resulted in more cases of graft failure, acute GVHD, and TRM than in RIC patients.

Allogeneic hematopoietic stem cell transplantation for chronic myeloid leukemia

There never has been a more difficult time to advise patients newly diagnosed with chronic myeloid leukemia (CML). Until recently,the options comprised noncurative but relatively nontoxic chemotherapy or potentially curative allogeneic stem cell transplantation,with its attendant morbidity and mortality. There now is the additional option of the tyrosine kinase inhibitor imatinib mesylate that has been in clinical practice for almost 5 years. Although data are emerging regarding the efficacy of imatinib, solid evidence of any prolongation in survival will be delayed for several years. Future management of CML will continue to depend on a combination of approaches that use allografting and targeted drug therapy. The next decade undoubtedly will witness the introduction of a number of agents capable of inhibiting signal transduction pathways,perhaps controlling CML in cases of primary or acquired imatinib resistance. In the absence of long-term outcome data for imatinib,it remains reasonable to propose that young patients with newly diagnosed CML who have HLA-identical or well-matched unrelated donors should undergo allogeneic transplantation using a standard or nonmyeloablative conditioning regimen. Similarly,patients who fail to respond to imatinib should be rescued with a transplant strategy. The role of molecular monitoring in these two strategies cannot be underestimated.

Increased risk of extensive chronic graft-versus-host disease after allogeneic peripheral blood stem cell transplantation using unrelated donors

The long-term follow-up of a study including 214 patients receiving either peripheral blood stem cells (PBSCs) or bone marrow (BM) from an HLA-A, -B, and -DR-compatible unrelated donor is presented. Median follow-up was 4.4 (2.3-7.3) and 5.0 (0.7-8.4) years in the 2 groups, respectively. Cumulative incidence of overall chronic graft-versus-host disease (GVHD) was similar in the 2 groups (78% vs 71%), while extensive chronic GVHD was significantly more common in the PBSC group compared with the BM group (39% vs 24%, P = .03). The 5-year transplant-related mortality (TRM) was 37% in the PBSC group and 35% in the BM controls (P = .7), and overall survival was 42% in both groups. The relapse incidences were 26% and 27% in the 2 groups, respectively, resulting in a disease-free survival of 41% in both groups. In conclusion, PBSCs from HLA-compatible unrelated donors results in similar outcome compared to BM but implies an increased risk for extensive chronic GVHD.

The source of cells for allografting

Peripheral blood is used almost exclusively as the source of hematopoietic cells for autografting, but the best source of cells for allografting is the subject of considerable discussion and debate. Randomized studies comparing unstimulated bone marrow with G-CSF-mobilized peripheral blood in the sibling allogeneic setting have indicated a trend to more chronic graft-versus-host disease in peripheral blood recipients. However, whether the use of G-CSF-mobilized peripheral blood cells leads to more acute graft-versus-host disease is uncertain. Adults undergoing sibling allografting appear to benefit in terms of improved disease-free survival or improved overall survival with the use of G-CSF-mobilized peripheral blood. It is not clear, however, whether these benefits also extend to children or those undergoing matched unrelated transplantation.

Diverse clinical applications using advantages of allogeneic peripheral blood stem cell transplantation

The diverse clinical applications of allogeneic peripheral blood stem cells based on use of their advantages are summarized. It is apparent that more stem cells and T-lymphocytes can be harvested by mobilization treatment with cytokines from healthy donors in allogeneic peripheral blood stem cell transplantation (PBSCT) than in bone marrow transplantation. It is also clear that a stronger graft-versus-tumor effect can be induced with allogeneic PBSCT than with bone marrow transplantation. One merit of allogeneic PBSCT is that it allows clinicians to design diverse clinical applications. It would appear that allogeneic PBSCT may be preferable in special clinical settings, such as advanced hematological malignancies, situations requiring a strong graft-versus-tumor effect, nonmyeloablative stem cell transplantation, and situations requiring a megadose of stem cells. Cytokine-primed peripheral blood stem cells can also be used for adoptive immunotherapy, such as a nonprimed donor lymphocyte infusion.

Dose Study of Thymoglobulin During Conditioning for Unrelated Donor Allogeneic Stem-Cell Transplantation

BACKGROUND

Steroid-related bone loss is a recognized complication after renal transplantation. In a prospective, randomized, multicenter study we compared the influence of a steroid-free immunosuppressive regimen with a regimen with limited steroid exposure on the changes in bone mass after renal transplantation.

METHODS

A total of 364 recipients of a renal transplant were randomized to receive either daclizumab (1 mg/kg on days 0 and 10 after transplantation; steroid-free group n=186) or prednisone (0.3 mg/kg per day tapered to 0 mg at week 16 after transplantation; steroids group n=178). All patients received tacrolimus, mycophenolate mofetil, and, during the first 3 days, 100 mg prednisolone intravenously. Changes in bone mineral density (BMD) were evaluated in 135 and 126 patients in the steroid-free and steroids group, respectively.

RESULTS

The mean (+/- SD) BMD of the lumbar spine decreased slightly in both groups during the first 3 months after transplantation (steroid-free -1.3 +/- 4.0% [P<0.01]; steroids -2.3 +/-4.2% [P<0.01]). In the following months, lumbar BMD recovered in both groups (P<0.01), resulting in a lumbar BMD at 12 months after transplantation comparable with the baseline value. No difference between the groups was found at 3 months (steroid-free versus steroids +1.0%; 95% confidence interval -0.0%-+2.0%, P=0.060) and at 12 months after transplantation (steroid-free versus steroids +0.9%; 95% confidence interval -0.8%-+2.6%, NS).

CONCLUSION

The use of a moderate dose of steroids during 4 months after transplantation has no important influence on bone mass during the first year after renal transplantation. On average, both regimens prevented accelerated bone loss.

Chimerism and clinical outcomes of 110 recipients of unrelated donor bone marrow transplants who underwent conditioning with low-dose, single-exposure total body irradiation and cyclophosphamide

We hypothesized that low-dose (550-cGy), single-exposure, high dose rate (30 cGy/min) total body irradiation (TBI) with cyclophosphamide as conditioning for HLA-compatible unrelated donor (URD) bone marrow transplantation (BMT) would result in donor chimerism (DC) with a low risk for serious organ toxicity and treatment-related mortality (TRM). Twenty-six patients with good risk diagnoses (acute leukemia in first complete remission [CR] and chronic-phase chronic myelogenous leukemia [CML]) and 84 with poor risk diagnoses underwent this regimen and URD BMT. Unsorted marrow nucleated cells were assessed for chimerism using VNTR probes. All DC occurred in 78 (86%) of 91 evaluable patients at 1 or more follow-up points. Graft failure occurred in 7 (7.7%) patients. Fatal organ toxicity occurred in only 2% of patients. TRM rates through 2 years of follow-up were 19% and 42% in those with good and poor risk diagnoses, respectively. Overall and disease-free survival rates in the good risk group were 47% and 40%, respectively, and in the poor risk group they were 25% and 21%, respectively, at a median follow-up for living patients of 850 days (range, 354-1588 days). This regimen resulted in 100% DC in most patients undergoing URD BMT with a relatively low risk for fatal organ toxicity and TRM.

Comparing morbidity and mortality of HLA-matched unrelated donor hematopoietic cell transplantation after nonmyeloablative and myeloablative conditioning: influence of pretransplantation comorbidities

We have carried out HLA-matched unrelated donor hematopoietic cell transplantation (HCT) after nonmyeloablative conditioning in patients with hematologic malignancies who were ineligible for conventional transplantations because of age, comorbidities, or both. The nonmyeloablative regimen consisted of 90 mg/m2 fludarabine and 2 Gy total body irradiation given before and mycophenolate mofetil and cyclosporine given after HCT. This report compares, retrospectively, morbidity and mortality among 60 consecutive patients given nonmyeloablative conditioning (nonablative patients) to those among 74 concurrent and consecutive patients given myeloablative conditioning (ablative patients) before unrelated HCT. The Charlson Comorbidity Index was used to assess pretransplantation comorbidities. Even though nonablative patients had significantly higher pretransplantation comorbidity scores, were older, and had more often failed preceding ablative transplantations and cytotoxic therapies, they experienced fewer grades III to IV toxicities than ablative patients. Further, the incidence of grades III to IV acute graft-versus-host disease (GVHD) was significantly lower in nonablative patients. Both patient groups had comparable 1-year probabilities of chronic GVHD. The 1-year nonrelapse mortality rate was 20% in nonablative patients compared to 32% in ablative patients (hazard ratio=1.4). After adjustment for pretransplantation differences between the 2 patient groups, the hazard ratio was 3.0 (P=.04). Multivariate analyses showed higher pretransplantation comorbidity scores to result in increased toxicity and mortality.

Hematopoietic stem cell transplantation: bone marrow vs. mobilized peripheral blood

Peripheral blood stem cells have largely replaced bone marrow as the source of cells in autologous transplantation because of more rapid neutrophil and platelet recovery and faster immune reconstitution. Allogeneic peripheral blood stem cells similarly lead to faster hematologic recovery: however, their effects on graft-vs.-host disease, relapse, survival, and immune reconstitution have been less certain. Eight randomized trials have been published to date comparing the clinical outcomes of allogeneic-related donor bone marrow transplantation (BMT) vs. PBSCT and will be reviewed. In addition, comparisons between the two stem cell sources in unrelated donor transplantation and the increasingly utilized nonmyeloablative transplantation will be discussed.

Allogeneic hematopoietic stem cell transplantation for myeloproliferative disorders and myelodysplastic syndromes

Allogeneic SCT is the most effective method to achieve cure in patients with MPD and MDS. This approach is associated with significant risk of morbidity (eg, GVHD) and TRM, although the incidence and severity vary based on donor and recipient characteristics. For young patients with HLA-matched donors, SCT is the preferred therapy. Efforts to improve outcome for older patients and for patients with alternative donors have led to decreased treatment-associated complications with associated better long-term DFS.

HLA-matched unrelated donor hematopoietic cell transplantation after nonmyeloablative conditioning for patients with hematologic malignancies

A hematopoietic cell transplantation (HCT) approach was developed for elderly or ill patients with hematologic malignancies that employed nonmyeloablative conditioning to avoid common regimen-related toxicities and relied on graft-versus-tumor effects for control of malignancy. Eighty-nine patients, median age 53 years, were given fludarabine (90 mg/m2) and 2 Gy total body irradiation. Marrow (n = 18) or granulocyte colony-stimulating factor (G-CSF)-stimulated peripheral blood mononuclear cells (G-PBMCs; n = 71) were transplanted from unrelated donors matched for human leukocyte antigen A (HLA-A), -B, -C antigens and -DRB1 and -DQB1 alleles. Postgrafting immunosuppression included mycophenolate mofetil and cyclosporine. Donor T-cell chimerism was higher for G-PBMCs compared with marrow recipients. Durable engraftment was observed in 85% of G-PBMCs and 56% of marrow recipients. Cumulative probabilities of grade II, III, and IV acute graft-versus-host disease (GVHD) were 42%, 8%, and 2%, respectively. Nonrelapse mortality at day 100 and at 1 year was 11% and 16%, respectively. One-year overall survivals and progression-free survivals were 52% and 38%, respectively. G-PBMC recipients had improved survival (57% vs 33%) and progression-free survival (44% vs 17%) compared with marrow recipients. HLA-matched unrelated donor HCT after nonmyeloablative conditioning is feasible in patients ineligible for conventional HCT. G-PBMCs conferred higher donor T-cell chimerism, greater durable engraftment, and better progression-free and overall survivals compared with marrow.

Chronic myelogenous leukemia

The treatment options for chronic myelogenous leukemia (CML) continue to evolve rapidly. Imatinib mesylate (Gleevec, Glivec, formerly STI571) has continued to show remarkable clinical benefits and the updated results with this agent are reviewed. As relapses using single agent imatinib have occurred, particularly in advanced phase patients, the issue of whether combinations of other antileukemic agents with imatinib may yield improved results is addressed. In addition, data on new agents that have potential in the treatment of CML are reviewed. These agents are presented in the context of their molecular mechanism of action. The most recent data for stem cell transplantation, along with advances in nonmyeloablative transplants, are also reviewed. In Section I, Drs. Stephen O'Brien and Brian Druker update the current status of clinical trials with imatinib and review ongoing investigations into mechanisms of resistance and combinations of imatinib with other agents. They also present their views on integration of imatinib with other therapies. In Section II, Dr. Jorge Cortes describes the most recent data on novel therapies for CML, including farnesyl transferase inhibitors, arsenic trioxide, decitabine, and troxatyl, among others. These agents are discussed in the context of their molecular mechanism of action and rationale for use. In Section III, Dr. Jerald Radich updates the results of stem cell transplants for CML, including emerging data on nonmyeloablative transplants. He also presents data on using microarrays to stratify patients into molecularly defined risk groups.

Impact of transplanted CD34+ cell dose in allogeneic unmanipulated peripheral blood stem cell transplantation

The impact of the CD34+ cell dose on chronic graft-versus-host disease (cGVHD) and the clinical outcome was analyzed in 41 consecutive adult patients submitted to allogeneic peripheral blood stem cell transplantation from HLA-identical siblings. The patients were classified into 'low' or 'high' CD34+ cell dose groups based on whether they received less or more than a median CD34+ cell dose of 10.5 x 10(6)/kg, respectively. There was a significant difference in the incidence of extensive cGVHD (low vs high group, 25.0 vs 66.7%, P=0.021) and relapse (47.6 vs 20.0%, P=0.049) between the two groups. With a median follow-up of 335 days, the 3-year survival estimate for the whole population was 47.9%, while that for the low and high groups was 29.9 and 67.8%, respectively (P=0.0434). An inverse relation was noted between the relapse rate and the incidence of extensive cGVHD (P=0.043). It would appear reasonable that the optimal dose of CD34+ cells should be determined based on the disease status or aggressiveness of the malignant cells in each patient. Yet, in the case of patients with a high risk of relapse, transplantation with a CD34+ cell dose of >10.5 x 10(6)/kg would seem to be acceptable to minimize the risk of relapse.

Chronic graft-versus-host disease

Chronic graft-versus-host disease (GVHD) remains a vexing and dangerous complication of allogeneic stem cell transplantation. Mild forms of chronic GVHD are often manageable with local or low-dose systemic immunosuppression and do not affect long-term survival. In contrast, more severe forms of chronic GVHD require intensive medical management and adversely affect survival. This report reviews current concepts of the pathogenesis, clinical risk factors, classification systems, organ manifestations, and available treatments for chronic GVHD. It also provides a comprehensive listing of the published clinical trials aimed at prevention and primary treatment of chronic GVHD.

Transplantation of highly purified CD34+ progenitor cells from unrelated donors in pediatric leukemia

Unrelated donors are commonly used for hematopoietic stem cell transplants, but graft-versus-host disease (GVHD) is a major problem. We investigated whether transplantation of purified mobilized peripheral-blood CD34(+) stem cells from unrelated donors would prevent acute and chronic GVHD in pediatric patients with leukemia and avert the need for pharmacologic immunosuppression. Thirty-one pediatric patients with acute lymphoblastic leukemia (ALL, n = 16), acute myeloid (n = 7), chronic myeloid (n = 6), or juvenile myelomonocytic leukemia (n = 2) underwent transplantation. The median purity of CD34(+) cells after positive magnet-activated cell sorting was 98.5%. Patients received a median of 8.0 x 10(6) CD34(+) cells and 6 x 10(3) CD3(+) T lymphocytes per kilogram, with no posttransplantation pharmacologic immunosuppression. Primary acute GVHD > or = grade II was seen in only 10% of patients (n = 3) and occurred only after human herpesvirus 6 (HHV 6) infection. Two patients had limited chronic GVHD. Engraftment occurred in all patients (primary engraftment, n = 26; engraftment after reconditioning, n = 5). The 2-year survival estimate was 38% for all patients and 63% for patients with ALL in complete remission. Patients with myeloid malignancies had a poor outcome. In comparison to a historical control group who received unmanipulated bone marrow, our patients had a lower incidence of GVHD (P <.001). No difference was observed in the probability of relapse or survival. Study patients with ALL in remission showed a trend toward better survival (P =.07). Transplantation of purified peripheral-blood CD34(+) cells from unrelated donors effectively minimizes GVHD and may be a good therapeutic option for patients with relapsed ALL.

A comparison of related donor peripheral blood and bone marrow transplants: importance of late-onset chronic graft-versus-host disease and infections

Peripheral blood hematopoietic stem cell (PBSC) transplants have been shown to result in more rapid engraftment than standard bone marrow transplants (BMTs). Little comparative data exist regarding complications in patients receiving transplants using these stem cell sources. In our study, 97 adults with advanced hematologic malignancies who received allogeneic PBSC transplants were compared with 97 adults who received allogeneic BMTs using identical preparative regimens and support parameters. The incidence of systemic infections and other major complications occurring within the first year after transplantation were calculated in both groups. Proportional hazard analysis was used to examine risk factors for death and complications in both groups. Patients receiving PBSC transplants had more rapid neutrophil (17 days versus 24 days; P <.001) and platelet engraftment (28 days versus 47 days; P <.001) than BMT recipients. The survival rate at 2 years was 38% in PBSC transplant recipients and 28% in marrow recipients (P =.08). There was no difference in rates of grade II to IV acute graft-versus-host disease (GVHD) between groups (PBSC 46%, BMT 51%; P =.3). PBSC transplant recipients were more likely to develop chronic GVHD after 180 days (hazard ratio 2.2; P =.05). Accompanying this "late-onset chronic GVHD," a pattern of more frequent late systemic fungal and cytomegalovirus infections was observed in PBSC transplant recipients. In conclusion, although PBSC transplant recipients engraft more quickly than BMT recipients and have somewhat better 2-year survival rates, they develop more frequent late-onset chronic GVHD and may have more late fungal and cytomegalovirus infections than marrow recipients. Further studies must examine this late-onset chronic GVHD and better characterize immune reconstitution in PBSC transplant recipients to understand their effects on patient recovery.

Patients with acute lymphoblastic leukaemia allografted with a matched unrelated donor may have a lower survival with a peripheral blood stem cell graft compared to bone marrow

We analysed data for 213 patients with ALL and AML who received either peripheral blood stem cells (PBSC) (n=74) or bone marrow (BM) (n=139) from an HLA-matched unrelated donor (EBMT acute leukaemia registry; January 1994 to January 1999). The two groups of patients (by cell source) were comparable with respect to age, sex, disease status, year at transplant and graft T cell depletion. Engraftment was achieved in about 90% regardless of stem cell source or leukaemia type. Kinetics of neutrophil and platelet recovery, similar for both sources in ALL patients, were faster for PBSC in AML patients. The incidence of acute graft-versus-host disease was similar for both sources in AML patients, but higher for PBSC in ALL patients (74 vs 54%, P=0.05). The 1-year probability of chronic graft-versus-host disease was 40 and 45% (P=0.66) in ALL patients compared to 49 and 35% (P=0.13) in AML patients (PBSC vs BM). In AML patients, none of the following differed significantly with cell source: transplant-related mortality, relapse incidence, leukaemia-free survival and overall survival. In ALL patients, the transplant-related mortality for PBSC vs BM was 61 vs 47% (P=0.13), the relapse incidence was 47 vs 39% (P=0.17), the leukaemia-free survival was 21 vs 32% (P=0.04) and the overall survival was 24 vs 34% (P=0.04). These data suggest that the short-term outcome of allogeneic PBSC is not significantly different from that of BM in AML patients who underwent a transplant from a matched unrelated donor but, conversely, that survival with PBSC may be decreased in ALL patients. In conclusion, the source of transplant cells needs to be evaluated by disease, especially when dealing with unrelated donors.

Invasive aspergillosis in allogeneic stem cell transplant recipients: changes in epidemiology and risk factors

The incidence of postengraftment invasive aspergillosis (IA) in hematopoietic stem cell transplant (HSCT) recipients increased during the 1990s. We determined risks for IA and outcomes among 1682 patients who received HSCTs between January 1993 and December 1998. Risk factors included host variables (age, underlying disease), transplant variables (stem cell source), and late complications (acute and chronic graft-versus-host disease [GVHD], receipt of corticosteroids, secondary neutropenia, cytomegalovirus [CMV] disease, and respiratory virus infection). We identified risk factors associated with IA early after transplantation (<or= 40 days) and after engraftment (41-180 days). Older patient age was associated with an increased risk during both periods. Chronic myelogenous leukemia (CML) in chronic phase was associated with low risk for early IA compared with other hematologic malignancies, aplastic anemia, and myelodysplastic syndrome. Multiple myeloma was associated with an increased risk for postengraftment IA. Use of human leukocyte antigen (HLA)-matched related (MR) peripheral blood stem cells conferred protection against early IA compared with use of MR bone marrow, but use of cord blood increased the risk of IA early after transplantation. Factors that increased risks for IA after engraftment included receipt of T cell-depleted or CD34-selected stem cell products, receipt of corticosteroids, neutropenia, lymphopenia, GVHD, CMV disease, and respiratory virus infections. Very late IA (> 6 months after transplantation) was associated with chronic GVHD and CMV disease. These results emphasize the postengraftment timing of IA; risk factor analyses verify previously recognized risk factors (GVHD, receipt of corticosteroids, and neutropenia) and uncover the roles of lymphopenia and viral infections in increasing the incidence of postengraftment IA in the 1990s.

The graft-versus-leukaemia effect in haematopoietic stem cell transplantation using unrelated donors

We studied the graft-versus-leukaemia (GVL) effect in 185 patients with haematological malignancies who underwent unrelated donor haematopoietic stem cell transplantation (HSCT) at Huddinge University Hospital between May 1991 and June 2001. Ninety-five were in first CR/CP and 90 in later stages. Most (86%) of them had a HLA-A, -B and -DRbeta1 matched donor. Conditioning usually consisted of total body irradiation and cyclophosphamide, and GVHD prophylaxis of cyclosporine and methotrexate. In the multivariate risk-factor analysis of relapse, we found that disease stage beyond CR1/CP1 (P = 0.02), acute GVHD 0-I (P = 0.02), absence of chronic GVHD (P = 0.02) and ALL (P = 0.02) were independent risk factors for relapse. The incidence of relapse in those with acute GVHD grade II was 18% vs 46% in those with no or grade I (P = 0.04). In patients with or without chronic GVHD, the incidences of relapse were 32% and 48%, respectively (P < 0.01). The best RFS was seen in patients with chronic GVHD. No difference in RFS was seen in patients with no, mild or moderate acute GVHD. Risk factors for relapse after HSCT with unrelated donors were: acute lymphoblastic leukaemia, disease stage beyond CR1/CP1, absence of chronic GVHD and no, or mild acute GVHD. Overall and relapse-free survival were not improved by the occurrence of acute GVHD.

CD34+-enriched peripheral blood progenitor cells from unrelated donors for allografting of adult patients: high risk of graft failure, infection and relapse despite donor lymphocyte add-back

Fifty-one adults with haematological malignancies were transplanted with CD34+-selected peripheral blood progenitor cells (PBPC) from unrelated donors. The conditioning protocol contained total body irradiation (n = 17) or combinations of busulphan and other alkylating agents (n = 34). Antithymocyte globulin was infused in all patients. The median number of CD3+ T cells infused with the graft after purification with the Isolex 300 system in the first cohort of 18 patients was 2.1 x 10(5)/kg. Prophylactic donor lymphocyte infusion (DLI) containing 1 x 10(5) CD3+ T cells was performed on d 21 in the following 33 patients who had received PBPC purified by the CliniMACS system. Early graft failure occurred in 8/51 patients (16%). After a median follow-up of 31 months (range 8-60), the probability of disease-free survival (DFS) was 36% for the whole group. Reasons for death were opportunistic infections (n = 15), graft-versus-host disease (GvHD, n = 7) and relapse (n = 4). Pre-transplant factors with significant impact on DFS were cytomegalovirus status and risk category of underlying disease. The occurrence of graft failure or GvHD was associated with poor outcome. Recipients of CD34+-selected PBPC from unrelated donors are at high risk of infectious complications, relapse and graft failure which cannot be prevented by early reinfusion of unmodified donor lymphocytes.

In vivo T cell depletion with low-dose rabbit antithymocyte globulin results in low transplant-related mortality and low relapse incidence following unrelated hematopoietic stem cell transplantation

Stem cell transplantation from unrelated donors is associated with an increased risk of graft failure and graft-versus-host disease (GVHD). Addition of pretransplant antithymocyte globulin (ATG), although reducing the risk of graft rejection and GVHD, bears the risk of overimmunosuppression, resulting in an increased relapse rate and transplant-related mortality. Therefore, we evaluated in 21 consecutive patients receiving unrelated stem cell grafts from either HLA-matched (38%) or -mismatched (62%) donors whether low-dose rabbit ATG added to cyclosporin A and methotrexate at a total dose of 3.5 mg/kg for HLA-identical and 5.0 mg/kg for HLA-mismatched transplants given in two divided doses on days -2 and -1 provides sufficient immunosuppression for prevention of GVHD and graft rejection but is associated with an acceptable risk of relapse and transplant-related mortality. Stable leukocyte engraftment was achieved in all patients (100%). Overall survival after a median follow-up of 26 (median, range 14-42) months was 56 +/- 26% (95% confidence interval, CI) and the overall relapse rate at 3 years was 24 +/- 21%. Three-year survival for standard-risk patients, i.e., chronic myeloid leukemia (CML) in first chronic phase or acute leukemia in first complete remission, was 87% +/- 13% versus 40% +/- 31% for patients with more advanced disease. The incidence of acute GVHD II-IV degrees was 55 +/- 22%; that of severe acute GVHD III-IV degrees was 21 +/- 19%. Chronic GVHD was observed in 5/17 (29%) patients surviving more than 100 days post stem cell transplantation. Transplant-related mortality was 16 +/- 15% (95% CI) at day + 100 and 25 +/- 19% (95% CI) at 1 year after the transplant. The data presented show that pretransplant in vivo T cell depletion with low-dose rabbit ATG results in a low transplant-related mortality due to a low incidence of severe acute and chronic GVHD and a low relapse rate. To find out the optimal rabbit ATG dose in the unrelated stem cell transplantation setting, further dose-finding studies comparing high- and low-dose regimens are necessary.

Extracorporeal photopheresis in chronic graft-versus-host disease

Despite significant advances in stem cell manipulation and post-transplant immunosuppression, chronic graft-versus-host disease (cGVHD) remains a cause of major long-term morbidity in survivors of allogeneic stem cell transplantation. Extracorporeal photopheresis (ECP) is a novel therapeutic intervention which has demonstrated efficacy in patients with refractory acute and chronic GVHD. Clinical responses have been reported in skin and visceral GVHD. While the long-term immunomodulatory effects of ECP in cGVHD are unknown, recent studies of patients undergoing a 6- to 12-month course of ECP treatment demonstrated an attenuation of Th1-mediated cytokine secretion by activated T-helper cells, a shift in the DC1/DC2 ratio favoring plasmacytoid rather than monocytoid dendritic cell profiles, and a decrease in antigen responsiveness by dendritic cells. The implications of these immunomodulatory effects of ECP on pathogenesis and clinical outcome remains a fertile area for future research.

Acute lymphoblastic leukemia

This is a comprehensive overview on the most recent developments in diagnosis and treatment of acute lymphoblastic leukemia (ALL). Dr. Dieter Hoelzer and colleagues give an overview of current chemotherapy approaches, prognostic factors, risk stratification, and new treatment options such as tyrosine kinase inhibitors and monoclonal antibodies. Furthermore the role of minimal residual disease (MRD) for individual treatment decisions in prospective clinical studies in adult ALL is reviewed. Drs. Ching-Hon Pui and Mary Relling discuss late treatment sequelae in childhood ALL. The relation between the risk of second cancer and treatment schedule, pharmacogenetics, and gene expression profile studies is described. Also pathogenesis, risk factors, and management of other complications such as endocrinopathy, bone demineralization, obesity, and avascular necrosis of bone is reviewed. Dr. Fred Appelbaum addresses long-term results, late sequelae and quality of life in ALL patients after stem cell transplantation. New options for reduction of relapse risk, e.g., by intensified conditioning regimens or donor lymphocyte infusions, for reduction of mortality and new approaches such as nonmyeloablative transplantation in ALL are discussed. Drs. Jacques van Dongen and Tomasz Szczepanski demonstrate the prognostic value of MRD detection via flow cytometry or PCR analysis in childhood ALL. They discuss the relation between MRD results and type of treatment protocol, timing of the follow-up samples, and the applied technique and underline the importance of standardization and quality control. They also review MRD-based risk group definition and clinical consequences.

Hematopoietic stem cell transplantation after reduced-intensity conditioning as treatment of sickle cell disease

OBJECTIVE

Sickle cell disease generates considerable morbidity and mortality. Allogeneic hematopoietic stem cell transplantation (SCT) has the potential of curing the disease and halting end-organ damage. However, in older patients this treatment is associated with a significant risk of toxicity and death. SCT after reduced-intensity conditioning (RIC) might be a safer approach for the treatment of sickle cell disease.

MATERIALS AND METHODS

A 22-year-old male had experienced multiple, life-threatening hemolytic crises. We treated him with G-CSF-mobilized stem cells from his heterozygote, human leukocyte antigen-matched brother after RIC with fludarabine and cyclophosphamide. GVHD prophylaxis consisted of cyclosporine (CyA) and mycophenolate mofetil (MMF). Chimerism of peripheral blood mononuclear cells was evaluated using short tandem repeat analysis and hemoglobin analysis was performed by high-performance liquid chromatography.

RESULTS

There were no major treatment-related toxicities. At day +30 after transplantation the patient had mixed hematopoietic chimerism, which later converted to full chimerism. Hemoglobin analysis revealed 3.4% HbA(2), 1.0% HbF, and 41.2% HbS, which essentially is the same hemoglobin partition as in his brother's blood. MMF was discontinued on day +35 and CyA on day +120. After discontinuation of CyA the patient developed mild chronic GVHD, which resolved with continued CyA, low-dose steroids, and the retinoid isotretinoin. He is doing well on day +315 without evidence of GVHD.

CONCLUSIONS

Allogeneic SCT after RIC is feasible in adult patients with sickle cell disease. Mixed chimerism is sufficient to relieve disease-related symptoms and is possibly correlated with less acute GVHD.