Allogeneic transplantation of CD34(+) selected cells from peripheral blood from human leukocyte antigen-identical siblings: detrimental effect of a high number of donor CD34(+) cells?

Shared graft-versus-leukemia minor histocompatibility antigens in DISCOVeRY-BMT

T-cell responses to minor histocompatibility antigens (mHAs) mediate graft-versus-leukemia (GVL) effects and graft-versus-host disease (GVHD) in allogeneic hematopoietic cell transplantation. Therapies that boost T-cell responses improve allogeneic hematopoietic cell transplant (alloHCT) efficacy but are limited by concurrent increases in the incidence and severity of GVHD. mHAs with expression restricted to hematopoietic tissue (GVL mHAs) are attractive targets for driving GVL without causing GVHD. Prior work to identify mHAs has focused on a small set of mHAs or population-level single-nucleotide polymorphism-association studies. We report the discovery of a large set of novel GVL mHAs based on predicted immunogenicity, tissue expression, and degree of sharing among donor-recipient pairs (DRPs) in the DISCOVeRY-BMT data set of 3231 alloHCT DRPs. The total number of predicted mHAs varied by HLA allele, and the total number and number of each class of mHA significantly differed by recipient genomic ancestry group. From the pool of predicted mHAs, we identified the smallest sets of GVL mHAs needed to cover 100% of DRPs with a given HLA allele. We used mass spectrometry to search for high-population frequency mHAs for 3 common HLA alleles. We validated 24 predicted novel GVL mHAs that are found cumulatively within 98.8%, 60.7%, and 78.9% of DRPs within DISCOVeRY-BMT that express HLA-A∗02:01, HLA-B∗35:01, and HLA-C∗07:02, respectively. We confirmed the immunogenicity of an example novel mHA via T-cell coculture with peptide-pulsed dendritic cells. This work demonstrates that the identification of shared mHAs is a feasible and promising technique for expanding mHA-targeting immunotherapeutics.

Total nucleated cell dose in graft is a better prognostic factor for survival in pediatric patients transplanted with bone marrow compared to CD34+, CD3+, or total mononuclear cell count

BACKGROUND

Most studies investigating the impact of graft composition on transplant-related outcomes have focused on the effect of CD34+ cell dose and reported equivocal results. The aim of this study is to investigate the impact of doses of total nucleated cells (TNCs), total mononuclear cells (TMCs), CD3+, and CD34+ cells on the outcome of children receiving allogeneic hematopoietic stem cell transplantation (HSCT).

METHODS

Children and adolescents who underwent allogeneic HSCT for malignant hemato-oncological diseases or nonmalignant diseases in Cukurova University Faculty of Medicine, Pediatric Bone Marrow Transplantation Center between 2010 and 2020 were enrolled in the study.

RESULTS

A total of 212 patients receiving allogeneic HSCT (154 bone marrow transplantation; 58 peripheral blood stem cell transplantation) from matched related or unrelated donors were included in the study. Higher TNC doses associated with a superior 5-year event-free survival (EFS; 67.7% vs 44.7%) in the whole group (log-rank P = .027). Overall survival (OS) and EFS of bone marrow-transplanted patients differed significantly according to TNC doses (log-rank P = .041 and .027, respectively). Multivariant analysis for OS revealed a P value of .038 for TNC, Exp(B) = 1.939 (95% CI: [1.038, 3.621]). That for EFS revealed a P value of .025 for TNC, Exp(B) = 1.992 (95% CI: [1.088, 3.647]). There was no relationship between doses of CD34+ cells, CD3+ cells, TMC, TNC, and neutrophil or platelet engraftment.

CONCLUSION

Our data suggest that TNC dose is a better prognostic factor for pediatric allogeneic HSCT outcomes than doses of CD34+ cells, CD3+ cells, or TMC in patients transplanted with bone marrow. Future studies analyzing cell subsets and other components in TNC could elaborate the factor(s) accompanying this observed survival advantage.

Use of plerixafor to mobilize haematopoietic progenitor cells in healthy donors

Increased transplant activity calls for improved stem cell collection, especially when peripheral blood is the preferred source of haematopoietic progenitor cells (HPCs). Plerixafor is a bicyclam molecule that mobilizes CD34+ cells by reversibly disrupting CXCR4-CXCL12-supported HPC retention. Plerixafor is given with granulocyte colony-stimulating factor (G-CSF) to help harvest autologous CD34+ cells for transplantation when mobilization with G-CSF fails. Mobilization protocols with the same doses of plerixafor and G-CSF have been used off-label in healthy allogeneic donors, with equal success and scarce side effects, both in adult and paediatric patients. Plerixafor has also been used as a sole mobilization agent. Plerixafor alone or coupled with G-CSF might lead to harvesting distinct cellular populations conferring improved engraftment properties and increased survival. Those characteristics might make plerixafor an especially attractive mobilization agent, particularly for non-related donations. However, available data are limited, and long-term follow-up is needed to clarify the best scenario for using plerixafor with or without G-CSF in healthy donors. In this review, we will summarize the evidence supporting this practice, highlighting the practical aspects and providing clues for an expanded use of plerixafor.

The apheresis content analysis in Allo-HSCT represents reliable influential factors on graft-versus-host disease and overall survival

BACKGROUND

Hematopoietic stem cell transplantation (HSCT) is an established treatment for hematologic malignancies. However the post-HSCT outcome can be affected by multiple pre-transplant, transplant, and post-transplant factors. The cellular content of graft could be possible factors influencing the graft-versus-host disease (GVHD) and overall survival (OS) as transplantation outcomes.

PURPOSE

The aim of this study was to assess the impact of infused CD34+ cells, CD3+ cells, and MNC count on the patients' survival and incidence of graft-versus-host disease (GVHD).

MATERIAL AND METHODS

We analyzed 87 patients with hematological malignancies who underwent allogeneic hematopoietic stem cell transplantation at the Taleghani Stem Cell Transplantation and Cell therapy center, Tehran, Iran from January 2016 to December 2018. Patients were conditioned with either myeloablative conditioning regimen or reduced-intensity regimen.

RESULT

A CD34⁺ cell dose < 4.35 × 10⁶/kg and CD3⁺ cell dose < 365 × 10⁶/kg was associated with higher survival and lower acute and chronic GVHD incidence, although their association was not statistically significant. Moreover, there was a significant association between MNC count < 6.15 × 10⁸/kg and acute GVHD incidence.

CONCLUSION

Graft cell dose, lower than the cut-off level, could lead to better outcomes after allogeneic transplantation. However, this study showed that future investigations are required in a larger population of patients in order to determine the exact effect of allogeneic graft cell dose on transplantation outcome.

CD34+ cell dose effects on clinical outcomes after T-cell replete haploidentical allogeneic hematopoietic stem cell transplantation for acute myeloid leukemia using peripheral blood stem cells. A study from the acute leukemia working Party of the European Society for blood and marrow transplantation (EBMT)

Previous observations have reported controversial conclusions regarding cell dose and survival endpoints after allogeneic hematopoietic stem cell transplantation (HSCT). We conducted a retrospective analysis on 414 adult patients (median age 54 years, range, 18-74 years) with acute myeloid leukemia (AML) in first and second complete remission. They received a T-cell replete allogeneic HSCT from haploidentical donors, using peripheral blood stem cells, between 2006-2018. Median number of infused CD34+ was 6.58 × 10⁶ /kg (range, 2.2-31.2 × 10⁶ /kg). Graft-vs-host disease (GVHD) prophylaxis was post-transplant cyclophosphamide in 293 patients and anti-lymphocyte serum in 121 patients. Conditioning was myeloablative in 179 patients and reduced-intensity in 235 patients. After a median follow-up of 23.3 months (range, 12.1-41.8 months), 2-year overall survival (OS) was 64.5% (95% CI 59.3%-69.7%) with leukemia-free survival (LFS) of 57.3% (95% CI 51.8%-62.7%) and non-relapse mortality (NRM) of 23.3% (95% CI 19%-27.7%). Grades III-IV acute GVHD day+100 incidence was 14.6% while extensive chronic GVHD was 14.4% at 2-years. Thirteen (3.2%) patients experienced graft failure. We found the optimal CD34+/kg threshold defining high (n = 334) vs low cell dose (n = 80) at 4.96 × 10⁶ . Recipients of >4.96 × 10⁶ /kg CD34+ cells experienced less NRM (Hazard ratio [HR] 0.48; 95% CI 0.30-0.76) and prolonged LFS (HR 0.63; 95% CI 0.43-0.91) and OS (HR 0.60; 95% CI 0.40-0.88) compared to those in the lower cell dose cohort. Larger cohort studies are needed to confirm these findings.

Allogeneic Peripheral Blood Stem Cell Transplant: Correlation of Donor Factors with Yield, Engraftment, Chimerism, and Outcome: Retrospective Review of a Single Institute During a 3-Year Period

BACKGROUND

Donor factors have a variable correlation with cluster of differentiation (CD)34+ cell dose in allogeneic peripheral blood stem cell (PBSC) harvests. CD34+ cell dose affects the speed of hematopoietic recovery and percentage of donor chimerism in the recipient.

METHODS

A total of 25 allogeneic PBSC transplants performed during a 3-year period were included. All donors underwent mobilization with filgrastim. Leukapheresis, flowcytometric CD34+ cell enumeration, and chimerism analysis were performed and correlated with recipient outcome.

RESULTS

Besides age, all other donor parameters had a positive correlation with CD34+ cell count. Engraftment kinetics and chimerism had a positive correlation with the CD34+ yield of the PBSC product. Acute graft-vs-host disease (GVHD) was observed in patients with complete chimerism at day 30 after transplantation.

CONCLUSION

Adequate CD34+ cell yield happens in healthy donors, independent of donor demographic patterns with G-CSF only. A diverse population of donors can thus be approached for Matched Unrelated Donor (MUD) transplants. An accurate quantitative analysis of early donor chimerism in the recipient (at day 30) is an excellent tool for post-transplant monitoring for acute GvHD.

Emerging strategies for enhancing the homing of hematopoietic stem cells to the bone marrow after transplantation

Bone marrow failure is the primary cause of death after nuclear accidents or intentional exposure to high or low doses of ionizing radiation. Hematopoietic stem cell transplantation is the most potent treatment procedure for patients suffering from several hematopoietic malignancies arising after radiation injuries. Successful hematopoietic recovery after transplantation depends on efficient homing and subsequent engraftment of hematopoietic stem cells in specific niches within the bone marrow. It is a rapid and coordinated process in which circulating cells actively enter the bone marrow through the process known as transvascular migration, which involves the tightly regulated relay of events that finally leads to homing of cells in the bone marrow. Various adhesion molecules, chemokines, glycoproteins, integrins, present both on the surface of stem cells and sinusoidal endothelium plays a critical role in transvascular migration. But despite having an in-depth knowledge of homing and engraftment and the key events that regulate it, we are still not completely able to avoid graft failures and post-transplant mortalities. This deems it necessary to design a flawless plan for successful transplantation. Here, in this review, we will discuss the current clinical methods used to overcome graft failures and their flaws. We will also discuss, what are the new approaches developed in the past 10-12 years to selectively deliver the hematopoietic stem cells in the bone marrow by adopting proper targeting strategies that can help revolutionize the field of regenerative and translational medicine.

The CD34+ Cell Dose Matters in Hematopoietic Stem Cell Transplantation with Peripheral Blood Stem Cells from Sibling Donors

The effect of CD34⁺ cell dose in allogeneic hematopoietic stem cell transplantation (HSCT) on overall survival (OS) and incidence of acute and chronic graft-versus-host disease (GvHD) has not been established and few studies have been performed. Our single center analysis included 189 patients with hematological malignancies who received peripheral blood stem cell (PBSC) grafts from sibling donors. Myeloablative conditioning was used in 88 cases and 101 received reduced intensity conditioning. The median CD34⁺ cell dose was 5.6 × 10⁶/kg (0.6–17.0). In the multivariate analysis, a CD34 cell dose of 6–7 × 10⁶/kg was associated with better OS and lower transplant-related mortality (TRM), while a dose of <5 × 10⁶/kg led to increased relapse and reduced chronic GVHD (cGVHD). A high CD34 cell-dose (>6.5 × 10⁶/kg) correlated with less acute GVHD (aGVHD) II–IV. We conclude that the CD34 cell dose has an impact on the outcome of HSCT from sibling donor PBSCs.

A high CD34+ cell dose is associated with better disease-free survival in patients with low-risk diseases undergoing peripheral blood stem cell transplantation from HLA-matched related donors

To elucidate the impact of infused CD34⁺ cell doses on transplant outcome, we retrospectively analyzed 851 adult patients who received peripheral blood stem cell transplantation (PBSCT) from human leukocyte antigen (HLA)-matched related donors. The patients were divided into high- and low-CD34 groups at the cutoff value of 4.5 × 10⁶/kg. Overall, the high CD34 group showed early neutrophil and platelet recovery. Stratification of disease risks demonstrated that among the patients with low-risk diseases, the high-CD34 group showed better disease-free survival (DFS) (64.9% vs. 55.5%, P = 0.0415) than did the low-CD34 group, without any increase in graft-versus-host disease (GVHD). Meanwhile, a higher CD34⁺ cell dose had no impacts on the outcomes of patients with high-risk diseases. Multivariate analyses for the patients with low-risk diseases revealed that a high CD34⁺ cell dose (hazard ratio [HR] 0.72, P = 0.048) and development of grade III-to-IV acute GVHD (HR 1.64, P = 0.018) were significantly associated with DFS. An excessive dose of CD34⁺ cells (>8.0 × 10⁶/kg) led to an increase in acute GVHD. By stratification of disease risk, a CD34⁺ cell dose between 4.5 and 8.0 × 10⁶/kg can be suggested for patients with low-risk diseases who undergo PBSCT from HLA-matched related donors.

Impact of CD34+ cell dose on reduced intensity conditioning regimen haploidentical hematopoietic stem cell transplantation

OBJECTIVES

Haploidentical hematopoietic stem cell transplant (haplo-SCT) has been associated with higher rates of graft rejection, and a higher dose of CD34+ cell dose is frequently requested. We aim to explore the impact of CD34+ cell dose in peripheral blood stem cell (PBSC) grafts using reduced intensity conditioning (RIC) in haplo-SCT.

METHODS

Sixty-eight consecutive haplo-SCT in adult patients were included. Graft-vs-host disease (GVHD) prophylaxis consisted on ATG, PTCy, and CsA. The cohort was divided in two groups using CD34+ dose of ≥ 9 × 10⁶ CD34+/Kg as cutoff point. Median follow-up was 8.9 months.

RESULTS

Median cell dose infused was 9.32 × 10⁶ CD34+/Kg. Forty (58.8%) recipients received grafts with CD34+ cells ≥9 × 10⁶ /kg. The infusion ≥ 9 × 10⁶ CD34+/Kg cell dose had a negative impact in overall survival (P = .03) after adjusting for age at transplant. The cumulative incidence of acute GVHD and graft failure were not significantly influenced per CD34+ cell dose. Only four recipients had grade III aGVHD, and all of them received grafts with a CD34+ cell dose ≥ 9 × 10⁶ .

CONCLUSION

In RIC haplo-SCT, recipients may not benefit from PBSC grafts with a CD34+/kg cell dose higher than 9 × 10⁶ cells/kg, as it can have an adverse impact in post-transplant outcome.

Trends in peripheral stem/progenitor cell manipulation and clinical application

Transplants using peripheral blood hemopoietic stem/progenitor (PBHS) cells are widely performed for the treatment of patients with hematologic disorders in routine practice and clinical trials. Although the process from mobilization to infusion of PBHS cells has been mostly established, optimal conditions for each process remain undetermined. Adverse reactions caused by PBHS cell infusions have not been systematically recorded. In transplants using PBHS cells, a number of problems still exist. In this section, the current status of and future perspectives regarding PBHS cells are described.

High CD3+ and CD34+ peripheral blood stem cell grafts content is associated with increased risk of graft-versus-host disease without beneficial effect on disease control after reduced-intensity conditioning allogeneic transplantation from matched unrelated donors for acute myeloid leukemia - an analysis from the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation

Inconsistent results have been reported regarding the influence of graft composition on the incidence of graft versus host disease (GVHD), disease control and survival after reduced-intensity conditioning (RIC) allogeneic peripheral blood stem cell transplantation (allo-PBSCT). These discrepancies may be at least in part explained by the differences in disease categories, disease status at transplant, donor type and conditioning. The current retrospective EBMT registry study aimed to analyze the impact of CD3+ and CD34+ cells dose on the outcome of RIC allo-PBSCT in patients with acute myelogenous leukemia (AML) in first complete remission, allografted from HLA-matched unrelated donors (10 of 10 match). We included 203 adults. In univariate analysis, patients transplanted with the highest CD3+ and CD34+ doses (above the third quartile cut-off point values, >347 x 10^6/kg and >8.25 x 10^6 /kg, respectively) had an increased incidence of grade III-IV acute (a) GVHD (20% vs. 6%, P = .003 and 18% vs. 7%, P = .02, respectively). There was no association between cellular composition of grafts and transplant-related mortality, AML relapse, incidence of chronic GVHD and survival. Neither engraftment itself nor the kinetics of engraftment were affected by the cell dose. In multivariate analysis, CD3+ and CD34+ doses were the only adverse predicting factors for grade III-IV aGVHD (HR = 3.6; 95%CI: 1.45-9.96, P = .006 and 2.65 (1.07-6.57), P = .04, respectively). These results suggest that careful assessing the CD3+ and CD34+ graft content and tailoring the cell dose infused may help in reducing severe acute GVHD risk without negative impact on the other transplantation outcomes.

Regulation of the embryonic erythropoietic niche: a future perspective

The production of red blood cells, termed erythropoiesis, occurs in two waves in the developing mouse embryo: first primitive erythropoiesis followed by definitive erythropoiesis. In the mouse embryo, both primitive and definitive erythropoiesis originates in the extra-embryonic yolk sac. The definitive wave then migrates to the fetal liver, fetal spleen and fetal bone marrow as these organs form. The fetal liver serves as the major organ for hematopoietic cell expansion and erythroid maturation after mid-gestation. The erythropoietic niche, which expresses critical cytokines such as stem cell factor (SCF), thrombopoietin (TPO) and the insulin-like growth factors IGF1 and IGF2, supports hematopoietic expansion in the fetal liver. Previously, our group demonstrated that DLK1⁺ hepatoblasts support fetal liver hematopoiesis through erythropoietin and SCF release as well as extracellular matrix deposition. Loss of DLK1⁺ hepatoblasts in Map2k4^−/− mouse embryos resulted in decreased numbers of hematopoietic cells in fetal liver. Genes encoding proteinases and peptidases were found to be highly expressed in DLK1⁺ hepatoblasts. Capitalizing on this knowledge, and working on the assumption that these proteinases and peptidases are generating small, potentially biologically active peptides, we assessed a range of peptides for their ability to support erythropoiesis in vitro. We identified KS-13 (PCT/JP2010/067011) as an erythropoietic peptide-a peptide which enhances the production of red blood cells from progenitor cells. Here, we discuss the elements regulating embryonic erythropoiesis with special attention to niche cells, and demonstrate how this knowledge can be applied in the identification of niche-derived peptides with potential therapeutic capability.

Higher dose of CD34+ peripheral blood stem cells is associated with better survival after haploidentical stem cell transplantation in pediatric patients

Haploidentical stem cell transplantation (SCT) is increasingly used to treat pediatric patients with malignant or nonmalignant hematological disorders. The CD34+ dose of bone marrow or peripheral blood stem cells (PBSCs) has been shown to be an important determinant of the transplant outcome in adults under various preparative regimens. However, knowledge of the effect of the CD34+ dose in pediatric haploidentical SCT is limited. We analyzed the data of 348 pediatric patients (aged 2-18 years) with acute or chronic leukemia, myelodysplastic syndrome (MDS), and other hematological disorders that received a transplant between 2002 and 2012. The results of multivariate analysis showed that PBSC CD34+ counts greater than 1.01 × 10⁶  kg^-1 improved platelet engraftment, improved overall survival, and reduced nonrelapse mortality. In contrast, a higher PBSC CD34+ dose did not affect the incidence of acute or chronic graft-versus-host disease, including engraftment syndrome. These data suggest that a PBSC CD34+ dose greater than 1.01 × 10⁶  kg^-1 is optimal for pediatric haploidentical SCT.

Low CD34 dose is associated with poor survival after reduced-intensity conditioning allogeneic transplantation for acute myeloid leukemia and myelodysplastic syndrome

Reduced-intensity conditioning/nonmyeloablative conditioning regimens are increasingly used in allogeneic hematopoietic cell transplantation (HCT). Reports have shown CD34(+) dose to be important for transplantation outcome using myeloablative conditioning. The role of CD34(+) dose of peripheral blood progenitor cells (PBPC) has not been previously analyzed in a large population undergoing reduced-intensity conditioning/nonmyeloablative HCT. We studied 1054 patients, ages 45 to 75 years, with acute myeloid leukemia or myelodysplastic syndrome who underwent transplantation between 2002 and 2011. Results of multivariate analysis showed that PBPC from HLA-matched siblings containing <4 × 10(6) CD34(+)/kg was associated with higher nonrelapse mortality (hazard ratio [HR], 2.03; P = .001), overall mortality (HR, 1.48; P = .008), and lower neutrophil (odds ratio [OR], .76; P = .03) and platelet (OR, .76; P = .03) recovery. PBPC from unrelated donors with CD34(+) dose < 6 × 10(6) CD34(+)/kg was also associated with higher nonrelapse (HR, 1.38; P = .02) and overall mortality (HR, 1.20; P = .05). In contrast to reports after myeloablative HCT, CD34(+) dose did not affect relapse or graft-versus-host disease with either donor type. An upper cell dose limit was not associated with adverse outcomes. These data suggest that PBPC CD34(+) doses >4 × 10(6) CD34(+)/kg and >6 × 10(6) CD34(+)/kg are optimal for HLA-matched sibling and unrelated donor HCT, respectively.

Higher doses of CD34+ progenitors are associated with improved overall survival without increasing GVHD in reduced intensity conditioning allogeneic transplant recipients with clinically advanced disease

OBJECTIVE

The influence of CD34+ cell dose on the outcome of allogeneic peripheral blood stem cell (PBSC) transplantation after reduced intensity conditioning (RIC) remains controversial. The impact of the number of CD34+ hematoprogenitors infused on transplant outcome and on the incidence of graft versus host disease (GVHD) was analyzed.

MATERIALS AND METHODS

Data of 138 patients with advanced hematological diseases who received an allogeneic PBSC transplant after RIC were analyzed. Donors were mobilized with granulocyte colony-stimulating factor and underwent one to three apheresis procedures. Incidence of acute and chronic GVHD and overall and event-free survival (OS and EFS) was determined.

RESULTS

The median number of CD34+ cells infused was 5.57 × 10(6) kg(-1) (range: 1.1-15.6). There was no relationship between CD34+ cell dose and neutrophil or platelet engraftment. Patients receiving ≥5 × 10(6) kg(-1) CD34+ cells had a 63.1% 5-year OS when compared with 48.2% for those receiving a lower number (P = 0.024). At 5-year follow-up, there was no significant difference in EFS between the groups (44% vs. 42.8%, P = 0.426). No relationship between CD34+ cell dose and acute GVHD was found (P = 0.1). Relapse rate was the same in patients with and without acute GVHD (P = 0.117). A nonsignificant improvement on OS and EFS in patients who developed chronic GVHD was found (P = 0.57 and 0.41).

CONCLUSION

A CD34+ cell dose ≥5 × 10(6) kg(-1) was associated with a significantly higher OS, but no improved EFS in high-risk patients. The number of CD34+ progenitors infused had no influence on the incidence of acute or chronic GVHD.

CD34?+ cell dose and outcome of patients undergoing reduced-intensity-conditioning allogeneic peripheral blood stem cell transplantation

While in bone marrow allogeneic transplantation the infusion of high doses of progenitor stem cells has a favourable impact on outcome, due to a faster hematopoietic and immune recovery, in the peripheral blood allo-setting the infusion of a high number of CD34 cells increases the risk of extensive chronic graft vs. host disease (cGVHD). This higher incidence of extensive cGVHD has an adverse impact on outcome due to a higher transplant related mortality, specially among patients receiving T-cell depleted allogeneic transplantation with myeloablative conditioning. By contrast, patients undergoing reduced intensity conditioning regimen may benefit from increasing higher CD34 + cell doses, especially those categorized as high risk according to disease status at transplant. Thus, the source of progenitors cells, type of conditioning and GVHD prophylaxis, among other factors, may influence the effect of the progenitor cell dose on outcome after allogeneic transplant.

Combined islet and hematopoietic stem cell allotransplantation: a clinical pilot trial to induce chimerism and graft tolerance

To prevent graft rejection and avoid immunosuppression-related side-effects, we attempted to induce recipient chimerism and graft tolerance in islet transplantation by donor CD34+hematopoietic stem cell (HSC) infusion. Six patients with brittle type 1 Diabetes Mellitus received a single-donor allogeneic islet transplant (8611 +/- 2113 IEQ/kg) followed by high doses of donor HSC (4.3 +/- 1.9 x 10(6) HSC/kg), at days 5 and 11 posttransplant, without ablative conditioning. An 'Edmonton-like' immunosuppression was administered, with a single dose of anti-TNFalpha antibody (Infliximab) added to induction. Immunosuppression was weaned per protocol starting 12 months posttransplant. After transplantation, glucose control significantly improved, with 3 recipients achieving insulin-independence for a short time (24 +/- 23 days). No severe hypoglycemia or protocol-related adverse events occurred. Graft function was maximal at 3 months then declined. Two recipients rejected within 6 months due to low immunosuppressive trough levels, whereas 4 completed 1-year follow-up with functioning grafts. Graft failure occurred within 4 months from weaning (478 +/- 25 days posttransplant). Peripheral chimerism, as donor leukocytes, was maximal at 1-month (5.92 +/- 0.48%), highly reduced at 1-year (0.20 +/- 0.08%), and was undetectable at graft failure. CD25+T-lymphocytes significantly decreased at 3 months, but partially recovered thereafter. Combined islet and HSC allotransplantation using an 'Edmonton-like' immunosuppression, without ablative conditioning, did not lead to stable chimerism and graft tolerance.

Platelet count is a sensitive predictor of autologous peripheral blood progenitor cell collection yield in previously treated plasma cell disease patients

BACKGROUND

It is often a clinical dilemma to determine when to collect autologous peripheral blood progenitor cells (PBPCs) in patients who received prior chemotherapy. It is also challenging to predict if the collected cells will be enough for one or two transplants.

STUDY DESIGN AND METHODS

A total of 103 PBPC donors were followed to evaluate factors that predict poor autologous PBPC collection. The donors were categorized into three groups: plasma cell disorders (PCDs), lymphomas, and normal allogeneic donors.

RESULTS

Our evaluation showed that platelet (PLT) count before growth factor administration significantly correlated with total CD34+ cell yield (Spearman r = 0.38, p < 0.001). Further analysis showed this correlation was only significant in plasma cell disease patients who received prior chemotherapy (Spearman r = 0.5, p = 0.008). Baseline PLT counts did not correlate with PBPC collection yield in untreated PCD, lymphoma, and normal allogeneic donors. In addition, daily PLT count during PBPC harvest correlated with CD34+ cell yield for that day (Spearman r = 0.41, p < 0.001). With a multiple linear regression model (adjusted R(2) = 0.31, AIC = 63.1), it has been determined that the baseline PLT count significantly correlates with total CD34+ cell yield in treated PCD patients.

CONCLUSION

Baseline PLT count is a sensitive indicator of autologous PBPC mobilization in PCD patients who received prior chemotherapy. This finding may be considered before growth factor administration to determine the optimal period to mobilize treated PCD patients and to predict if enough cells can be collected for one or two transplants.

Risk assessment in haematopoietic stem cell transplantation: Stem cell source

Bone marrow (BM) has been used for many years as the unique source of progenitor cells for allogeneic transplantation. However, two other sources of progenitor cells, peripheral blood (PB) and umbilical cord (UC), are being increasingly used. The type of graft is one of the most important factors in determining the speed and robustness of the reconstitution after the transplant of monocytes, T lymphocytes, B lymphocytes, NK cells, and dendritic cells. This fact is of especial relevance since the most important reactions after allogeneic transplants - e.g. graft-versus-host disease (GVHD), graft-versus-leukaemia effect (GvL), achievement of full donor chimerism, and fight against infections - are strongly influenced by a rapid and robust reconstitution of these cells. For this reason, the choice of the type of graft for allogeneic transplantation will influence the clinical outcome.

Comparison of outcomes after transplantation of peripheral blood stem cells versus bone marrow following an identical nonmyeloablative conditioning regimen

This is the first study to examine the outcomes in 54 patients with hematologic malignancies who received an HLA-matched related donor bone marrow (BM, n = 42) or GCSF-mobilized peripheral blood stem cells (PBSC, n = 12) following identical nonmyeloablative conditioning with the intention of induction of mixed chimerism (MC) followed by prophylactic donor leukocyte infusion (pDLI) to convert MC to full donor chimerism (FDC) and capture a graft-versus-tumor effect without clinical graft-versus-host disease (GVHD). Neutrophil and platelet recovery were faster and transfusion requirement was less in PBSC recipients (P < 0.05). A total of 48% of BMT recipients achieved FDC with a median conversion time of 84 days, including 13 following pDLI. In contrast, 83% (P = 0.04) in the PBSC group had spontaneous FDC at a median of 14 days, precluding the administration of pDLI. There was no significant difference in the incidences of acute or chronic GVHD, though the rates of chronic GVHD were considerably higher in PBSC group than in the BM group (6/7, 86% vs 10/24, 42%). CD4 and CD8 T-cell recovery was faster in PBSC recipients. In PBSC recipients, a higher number of CD34+ cells was associated with increased rates of severe, grade III-IV acute GVHD.

T-cell depleted peripheral blood stem cell allotransplantation with T-cell add-back for patients with hematological malignancies: effect of chronic GVHD on outcome

One hundred thirty-eight patients with hematologic malignancies received myeloablative T cell-depleted peripheral blood stem cell transplant (PBSCT) from an HLA-identical sibling donor. The T cell dose was adjusted to 0.2-1 x 10(5) CD3(+) cells/kg. The CD34 dose was 2.7-16 x 10(6)/kg. Patients with acute graft-versus-host disease (GVHD) grade <2 received 1 or 2 donor lymphocyte infusions of 10(7) CD3(+) cells/kg between days 45 and 100. Patients were designated according to relapse probability as standard or high relapse risk (77 and 61, respectively). Overall survival (OS), relapse-free survival, relapse, and transplant-related mortality (TRM) were 58%, 46%, 40%, and 20%, respectively, after a median follow-up of 4 years. Fifty-three (39%) and 21 (15%) patients developed grade 2-4 and 3-4 acute GVHD. Forty-two (36%) had limited and 29 (25%) had extensive chronic GVHD. In multivariate analysis, disease risk was an independent factor for OS and relapse, day-30 lymphocyte count for OS and TRM, and chronic GVHD for OS and relapse. PBSCT with early T cell add back leads to comparable rates of chronic GVHD compared with T cell-replete PBSCT. However, this chronic GVHD after T cell add back is associated with less mortality and retains a protective effect in terms of relapse, at least in the standard-risk patients.

Busulfan pharmacokinetics, toxicity, and low-dose conditioning for autologous transplantation of genetically modified hematopoietic stem cells in the rhesus macaque model

OBJECTIVE

Gene transfer to hematopoietic stem cells has recently been demonstrated to benefit a small number of patients in whom a selective advantage is conferred upon genetically modified cells; however, in disorders where no such selective advantage is conferred, conditioning appears necessary to allow adequate engraftment. To decrease the toxicity profile, we sought to develop nonmyeloablative conditioning regimens and in this work, explored the use of intravenous busulfan in a large animal model.

METHODS

Busulfan pharmacokinetics and toxicity were monitored in young rhesus macaques at two dosing levels (4 and 6 mg/kg). These doses were then employed to condition two animals at each dose level prior to autologous transplantation of genetically modified cells using our standard methods.

RESULTS

Busulfan pharmacokinetic (PK) data showed the area under the curve (AUC), drug half-life, and drug clearance were consistent within each dose group and similar to those reported in children. Single doses of busulfan were well tolerated and produced dose-dependent myelosuppression, most notably in the neutrophil and platelet counts. Although marking levels reached over 1% early in one animal, the long-term marking was low but detectable at 0.01 to 0.001%.

CONCLUSIONS

We conclude that low-dose intravenous bolus infusion of busulfan is well tolerated, has dose-dependent effects on peripheral blood counts, and allows long-term engraftment of genetically modified cells, but at levels too low for most clinical disorders.

Anti-D alloimmunization after D-mismatched allogeneic hematopoietic stem cell transplantation in patients with hematologic diseases

BACKGROUND

The de novo development of anti-D after D-mismatched allogeneic hematopoietic stem cell transplantation (AHSCT) is a possibility that must be considered. The transfusion of D- blood components after AHSCT has been recommended but anti-D alloimmunization in this setting has been studied little. Thus, the aim of this study was to analyze anti-D formation after D-mismatched AHSCT.

STUDY DESIGN AND METHODS

Thirty patients with a hematologic disease who underwent D-mismatched AHSCT were retrospectively studied. Support therapy included red blood cells (RBCs) and platelet (PLT) concentrates (PCs) from whole-blood donations and PLTs from apheresis. After AHSCT, patients received D+ PCs without administering Rh immunoglobulin (RhIG). An antibody screening to detect anti-D was performed by low-ionic-strength saline-indirect antiglobulin test with the tube test.

RESULTS

Fifteen D+ patients received stem cells (SCs) of D- donors and 15 D- patients received SCs of D+ donors. After AHSCT, patients received a median of 11.5 (range, 0-32) D- RBC units. D+ patients received 682 (83%) of 825 PLT units from D+ donors, and D- patients received 573 (85%) of 678 PLT units from D+ donors. None of the 30 patients developed anti-D after a median follow-up of 32 weeks (range, 4-310 weeks).

CONCLUSION

Anti-D alloimmunization after performing a D-mismatched AHSCT is infrequent in patients with hematologic diseases although patients receive D-mismatched PLT transfusions without RhIG administration.

Ideal rather than actual body weight should be used to calculate cell dose in allogeneic hematopoietic stem cell transplantation

Whether the CD34+ and CD3+ cell doses in allogeneic HSCT should be estimated using actual (ABW) or ideal (IBW) body weight has never been definitively determined. We have shown that CD34+ cell doses based upon IBW are better predictive of engraftment after autologous and allogeneic HSCT. Sixty-three patients undergoing reduced-intensity HSCT after a uniform preparative regimen were evaluated to determine the effect of cell dose. ABW and IBW were 45-147 kg (median 79) and 52-85 kg (median 67) respectively. The ABW-IBW difference was -24% to +133% (median +16%); nine patients were >5% underweight and 41 were >5% overweight. The CD34+ cell dose (10(6)/kg) was 1.4-11.8 (median 5) by IBW and 1.2-9.3 (median 4.5) by ABW. The CD3+ cell dose (10(8)/kg) was 0.9-14.9 (median 3) by IBW and 0.7-19.7 (median 2.7) by ABW. While CD34+ and CD3+ cell doses based upon IBW were found to affect transplant-related mortality, and disease-free and overall survival significantly, those based on ABW were either not predictive of outcome or the differences were of borderline significance. We suggest using IBW rather than ABW to calculate cell doses for HSCT; for statistical analyses and for clinical practice if a specific cell dose is being targeted.

Unrelated donor or partially matched related donor peripheral stem cell transplant with CD34+ selection and CD3+ addback for pediatric patients with leukemias

Unmodified peripheral stem cell transplants are associated with an increased risk of extensive chronic GVHD. T depletion may reduce this risk, but the risk of graft failure or relapse may increase. To decrease the risks of both extensive chronic GVHD and graft failure, we added back a defined dose of CD3+ cells to CD34+ selected PSCs. Twenty-four patients were evaluable for outcome analysis. Donors were unrelated (23) or related (1). Conditioning was thiotepa, cyclophosphamide, and total body irradiation. Cyclosporine was used post transplant. Following CD34+ selection, a total of 5 x 10(5)/kg CD3+ cells were infused. Donors were matched for 12 patients. The median CD34+ dose infused was 7.1 x 10(6)/kg. Engraftment occurred in all patients at a median of 14 days (10-19). Twelve patients are alive in remission 15-34 months (median, 25) post PSCT. GVHD occurred in 17 patients, but was >grade II in only 2. Chronic GVHD occurred in 61.5% of evaluable patients, but was limited to skin and perioral cavity. Two patients relapsed, and 10 patients died of non-relapse causes. This study demonstrates that PSCT with CD34+ selection and a defined dose of CD3+ results in prompt engraftment and may limit development of extensive chronic GVHD.

Sequential Regimen of Chemotherapy, Reduced-Intensity Conditioning for Allogeneic Stem-Cell Transplantation, and Prophylactic Donor Lymphocyte Transfusion in High-Risk Acute Myeloid Leukemia and Myelodysplastic Syndrome

Purpose

To improve the effect of allogeneic stem-cell transplantation by sequential use of intensive chemotherapy, reduced-intensity conditioning (RIC), and prophylactic donor lymphocyte transfusions (pDLTs) in high-risk acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS).

Patients and Methods

In a prospective study of 75 consecutive patients (median age, 52.3 years), high risk was defined by progressive or refractory disease (n = 59), second remission after early relapse (n = 8), or first remission with poor prognosis based on cytogenetics or delayed response to induction therapy (n = 8). Unfavorable karyotypes were found in 49% of informative patients, and 68 patients had medical contraindications against standard conditioning. Fludarabine (30 mg/m2), cytarabine (2 g/m2), and amsacrine (100 mg/m2) for 4 days were used for cytoreduction. After 3 days of rest, RIC consisted of 4 Gy total-body irradiation, antithymocyte globulin, and 80 to 120 mg/kg cyclophosphamide. Thirty-one patients had an HLA-identical sibling donor; 44 patients had an unrelated and/or HLA-mismatched donor. pDLT was given from day +120 in patients who were not receiving immunosuppression and were free of graft-versus-host disease (GvHD).

Results

Complete remission was induced in 66 patients (88%). With a median follow-up of 35.1 months (range, 13.6 to 47.6 months), 2-year overall and leukemia-free survival were 42% and 40%, respectively. Outcome of patients with refractory disease or with complex cytogenetic aberrations was identical to that of better prognostic subgroups. Survival was best in patients who received high CD34+ cell numbers, and in patients with limited GvHD.

Conclusion

Sequential use of intensive chemotherapy, RIC transplantation, and pDLT represents a promising approach to the treatment of high-risk AML and MDS, particularly in patients with most unfavorable prognoses.

Immune restoration following hematopoietic stem cell transplantation: an evolving target

Hematopoietic stem cell transplantation (HSCT) is the definitive cure for many malignant and nonmalignant diseases. However, delays in immune reconstitution (IR) following HSCT significantly limit the success of transplantation and increase the risk for infection and disease relapse in the transplant recipient. Therefore, ways to measure and to manipulate immune recovery following HSCT are emerging and their success depends directly upon an enhanced understanding for the underlying mechanisms responsible for reconstituted immunity and hematopoiesis. Recent discoveries in the activation, function, and regulation of dendritic cell (DC), natural killer (NK) cell, and T-lymphocyte subtypes have been critical in developing immunotherapies used to prevent graft-versus-host disease and to enhance graft-versus-leukemia. For example, regulatory T cells that induce tolerance and NK receptor-tumor ligand disparities that result in tumor lysis are being used to minimize GVHD and tumor burden, respectively. Furthermore, expansion and modulation of immune effector cells are being used to augment hematopoietic and immune recovery and to decrease transplant-related toxicity in the transplant recipient. Specifically, DC expansion and incorporation into antitumor and anti-microbial vaccines is fast approaching application into clinical trials. This paper will review our current understanding for IR following HSCT and the novel ways in which to restore immune function and decrease transplant-related toxicity in the transplant recipient.

Infused CD34+ cell dose predicts long-term survival in acute myelogenous leukemia patients who received allogeneic bone marrow transplantation from matched sibling donors in first complete remission

Allogeneic stem cell transplantation (ASCT) has improved the outcome of acute myelogenous leukemia (AML). To further improve the treatment outcome of ASCT in AML, finding a modifiable prognostic factor is mandatory. We evaluated the effect of CD34(+) cell dose on survival in allogeneic bone marrow transplantation (BMT) from HLA-matched sibling donors for AML patients in first complete remission (CR1). The 99 patients included in our analysis were classified into high CD34(+) cell dose group (CD34(+) cells > or = 2.5 x 10(6)/kg) and low CD34(+) cell dose group (CD34(+) cells < 2.5 x 10(6)/kg). The high CD34(+) cell dose patients had better overall survival (5-year overall survival rate, 75% +/- 6% vs 52% +/- 9%; P = .01) and leukemia-free survival (5-year leukemia-free survival rate, 70% +/- 6% vs 44% +/- 9%; P = .04). CD34(+) cell dose was the only independent prognostic factor in overall survival and leukemia-free survival. The high CD34(+) cell dose group had a lower relapse incidence with a borderline statistical significance (5-year relapse rate, 27% +/- 6% vs 50% +/- 10%; P = .09). There were no differences in the engraftment of neutrophil and platelet, grade II-IV acute graft-versus-host disease (GVHD), extensive-stage chronic GVHD, and transplant-related mortality between the high and low CD34(+) cell dose groups. We confirmed that high CD34(+) cell dose favorably affects the outcomes in allogeneic BMT for AML. The effort to attain a high CD34(+) cell dose should be pursued during bone marrow harvest in allogeneic BMT for AML in CR1.

The effect of peptide stimulation on haematopoietic stem cell mobilisation including engraftment characteristics and a note on donor side effects

Aplasia or irreversible bone marrow failure and a variety of haematologic malignancies, as well as an increasing number of solid tumours, currently include various forms of marrow or equivalent transplantation in routine management. In both allogeneic and autologous procedures stable recipient immunohaematopoietic reconstitution depends upon infusing the requisite population harvested at a precise time following commencement of a stimulatory peptide. In a first step this prospective study documented the safety of apheresis, defined side effects and enumerated mononuclear, CD34+ and CD3+ cells obtained. In the second stage delivery of the graft, characterised in this way and with the additional measurement of in vitro growth in clonogenic assay, to the suitably conditioned patient was correlated with recovery of neutrophil and platelet numbers appearing in the circulation. In a third and ongoing analysis the influence of passenger T-lymphocytes is being evaluated for impact on infection and a potential anti-tumour effect. The conclusion is that this technology is reliable, has a high degree of patient acceptability without untoward complications, and that local results correspond to international experience thereby providing an important and relevant measure of quality control.

CD8+ T cell dose affects development of acute graft-vs-host disease following reduced-intensity conditioning allogeneic peripheral blood stem cell transplantation

OBJECTIVE

Acute graft-vs-host disease (aGVHD) remains an important cause of morbidity after reduced-intensity conditioning (RIC) allogeneic transplantation (allo-SCT). It has been shown that antithymocyte globulin (ATG) dose infused during RIC is a major determinant for the likelihood of developing aGVHD. The ATG modulation on aGVHD is likely related to in vivo T-cell depletion.

PATIENTS AND METHODS

We therefore investigated the relationship between the cellular composition of the allograft and clinical outcome in 57 patients who received allogeneic peripheral blood stem cells from HLA-identical siblings following an ATG-based RIC.

RESULTS

In a multivariate analysis, the CD8+ T cell dose infused was the only parameter associated with the risk of aGVHD (p=0.031; RR=1.96; 95% CI, 1.1-3.6). When looking at the extremes, patients experiencing grade III-IV aGVHD received a median of 143 x 10(6)/kg CD8+ T cells, while patients without aGVHD received a median of 96 x 10(6)/kg CD8+ T cells (p=0.021). None of the different cell subtypes contained in the allograft was associated with a significant probability of developing chronic GVHD. Patients with grade II aGVHD who received an intermediate dose of CD8+ T cells (median, 111 x 10(6)/kg) had a significantly better overall survival in comparison to patients with grade 0-I or grade III-IV aGVHD (p=0.009).

CONCLUSION

In comparison to myeloablative allo-SCT, these results demonstrate that a cautious monitoring of the number of cells infused, at least in the context of ATG-based RIC, may represent an important predictive indicator of early transplant-related events and outcome after RIC allo-SCT.

CD34 cell selection of peripheral blood progenitor cells using the CliniMACS device for allogeneic transplantation: clinical results in 102 patients

The present study investigated the effects of CD34(+) cell selection in 102 patients using the CliniMACS device. Patients were at high risk for the development of graft versus host disease (GvHD) because of age, or the use of a haploidentical, mismatched or unrelated donor (UD). The median age of the patients was 44 years. The CliniMACS procedure yielded 8.0 x 10(6) CD34(+) cells/kg and the number of residual T cells was 1.3 x 10(4)/kg (median). The median follow up was 20.6 months. The probability of graft failure was 7%. The rate of acute GvHD was low (compatible family donors 10%, UDs 17%, and haploidentical donors 26%) with no patient enduring more than grade II disease. The cumulative incidence of chronic GvHD at the median follow up after transplant was 15% for the compatible family donor group, 40% for the UD group and 78% in the group transplanted from a haploidentical donor Treatment failure was mainly because of transplant-related mortality, especially aspergillus infection, and not due to relapse. The probability of disease-free survival, stratified for the risk of treatment failure, was 27% for the high risk, 46% for the intermediate risk and 83% for the low risk group.

Factors affecting reconstitution of the T cell compartment in allogeneic haematopoietic cell transplant recipients

The factors affecting T cell reconstitution post haematopoietic cell transplantation (HCT) are not well characterised. We carried out a longitudinal analysis of T cell reconstitution in 32 HCT recipients during the first 12 months post transplant. We analysed reconstitution of naïve, memory and effector T cells, their diversity and monitored thymic output using TCR rearrangement excision circles (TRECs). Thymic-independent pathways were responsible for the rapid reconstitution of memory and effector T cells less than 6 months post HCT. Thymic-dependent pathways were activated between 6 and 12 months in the majority of patients with naïve T cell numbers increasing in parallel with TREC levels. Increasing patient age, chronic GVHD and T cell depletion (with or without pretransplant Campath-1H) predicted low TREC levels and slow naïve T cell recovery. Furthermore, increasing patient age also predicted high memory and effector T cell numbers. The effects of post HCT immunosuppression, total body irradiation, donor leucocyte infusions, T cell dose and post HCT infections on T cell recovery were also analysed. However, no effects of these single variables across a variety of different age, GVHD and T cell depletion groups were apparent. This study suggests that future analysis of the factors affecting T cell reconstitution and studies aimed at reactivating the thymus through therapeutic intervention should be analysed in age-, GVHD- and TCD-matched patient groups.

Outcome of allogeneic peripheral blood stem cell transplantation using matched sibling donors in patients with high-risk hematological diseases

Although the use of peripheral blood stem cells instead of bone marrow is still a matter of debate in transplantation from HLA-identical sibling donors, allogeneic peripheral blood stem cell transplantation (PBSCT), with a stronger graft-versus-leukemia (GVL) effect, may be preferable as a source of stem cells, especially in the case of advanced hematologic diseases. As such, the current paper reports on the outcomes of 27 consecutive patients with high-risk hematologic diseases treated with allogeneic PBSCT. The median dose of CD34+, CD3+ cells, and MNC infused was 8.18 x 10(6)/kg (range: 2.78-14.93), 1.50 x 10(8)/kg (range: 0.06-4.25), and 7.17 x 10(8)/kg (range: 0.95-15.85), respectively. The median time taken for the ANC and platelets to reach 500 and 20,000 x 10(6)/microL was 15 (range: 9-25) and 16 d (range: 10-56), respectively. Three patients (11.1%) experienced transplant-related mortality within 90 d of transplantation, and 15 (62.5%) of 24 evaluated patients developed chronic graft-versus-host disease (GVHD; six limited, nine extensive). There was a significant difference in overall survival (OS) between the group with chronic GVHD and the group without chronic GVHD (P = 0.0253). The causes of death included relapse (six cases) and non-relapse mortality (infection: four cases, chronic GVHD-related death: three cases). The 4-yr OS rate and disease-free survival rate was 43.3 +/- 10.9% and 35.8 +/- 10.2%, respectively. Accordingly, chronic GVHD was found to have a positive role in patients with high-risk hematologic diseases that received allogeneic PBSCT.

Low dendritic cell count after allogeneic hematopoietic stem cell transplantation predicts relapse, death, and acute graft-versus-host disease

Dendritic cells (DCs) are key antigen-presenting cells with a potential role in tumor vaccines. We investigated the hypothesis that early reconstitution of DCs after allogeneic hematopoietic stem cell transplantation (SCT) improves survival. We also correlated DC reconstitution with complications of relapse and acute graft-versus-host disease (aGVHD). Fifty patients underwent transplantation between February 2000 and March 2003, with a median follow-up of 501 days (range, 136-1263 days). Most (92%) received blood stem cells, and the remainder received bone marrow from HLA-matched sibling donors for predominantly high-risk hematologic malignancies. Around the time of engraftment, peripheral blood underwent flow cytometry analysis for DCs, and the cells were divided as DC1 and DC2. Using Kaplan-Meier analysis, patients with lower DC counts (< 4.97 cells/microL) were found to have significantly worse survival (P =.002), increased incidence of relapse (P =.002), higher incidence of aGVHD onset (P =.0005), and a composite end point of relapse or death (P =.0017). A Cox proportional hazards multivariate model adjusted for important covariates confirmed that low DC count is independently associated with death (hazard ratio [HR], 3.8; P =.02), time to relapse (HR, 11.6; P =.001), and aGVHD (HR, 3.3; P =.04). Sensitivity and specificity rates for low DC count in predicting death or relapse are 73% and 75%, respectively. Low numbers of circulating DCs significantly increase the risk for relapse and acute GVHD and predict death after allogeneic SCT.

A randomized multicenter comparison of CD34(+)-selected progenitor cells from blood vs from bone marrow in recipients of HLA-identical allogeneic transplants for hematological malignancies

OBJECTIVE

Peripheral blood progenitor cells (PBPC) have been established as an alternative source of hematopoietic stem cells for allogeneic transplantation, but an increased incidence of both acute and chronic graft-vs-host disease (GVHD) has become apparent. We performed a prospective randomized trial comparing bone marrow transplantation (BMT) vs PBPC transplantation (PBPCT) using CD34(+) selection for T-cell depletion (TCD) in both study arms.

PATIENTS AND METHODS

Between January 1996 and October 2000, 120 patients with a diagnosis of acute leukemia, myelodysplasia, multiple myeloma, or lymphoma were randomized to receive either filgrastim-mobilized PBPC or BM from HLA-identical sibling donors after standard high-dose chemoradiotherapy. Patient characteristics did not differ between study arms.

RESULTS

Recipients of PBPC received more CD3(+) T cells (median: 3.0 vs 2.0 x 10(5)/kg, p<0.0001) and more CD34(+) cells (median: 3.6 vs 0.9 x 10(6)/kg, p<0.0001). Neutrophil and platelet recoveries occurred significantly faster after PBPCT. The cumulative incidence of acute GVHD grades II-IV was 37% after BMT vs 52% after PBPCT and was most significantly (p=0.007) affected by the number of CD3(+) T cells in the graft. Acute GVHD appeared strongly associated with increased treatment-related mortality (TRM) in a time-dependent analysis. Higher numbers of CD34(+) cells were associated with less TRM. With a median follow-up of 37 months (range: 12-75), overall survival at 4 years from transplantation was 60% after BMT and 34% for recipients of PBPCT (p=0.04), which difference was largely due to increased GVHD and TRM in PBPC recipients receiving T-cell dosages greater than 2 x 10(5)/kg.

CONCLUSION

Outcome following T cell-depleted PBPCT critically depends on the number of CD3(+) T cells, whereby high T-cell numbers may blunt a favorable effect of higher CD34(+) cell numbers.

Allogeneic graft CD34+ cell dose correlates with dendritic cell dose and clinical outcome, but not with dendritic cell reconstitution after transplant

OBJECTIVE

This study examined whether the CD34(+) cell dose in allografts correlates with the dose of myeloid dendritic cells (mDC) and plasmacytoid DC (pDC), and with DC reconstitution and clinical outcome after a myeloablative HLA-matched transplant.

PATIENTS AND METHODS

Fifty-three patients were included in this study: 37 who had undergone a granulocyte colony-stimulating factor mobilized peripheral blood stem cells (PBSC) transplant from related donors and 16 who had undergone a marrow transplant from unrelated donors. The number of CD34(+) cells, lin(-)HLA-DR(+)CD11c(+) mDC, lin(-)HLA-DR(+)CD123(+) pDC, CD14(+) monocytes, and CD3(+)CD4(+), CD3(+)CD8(+), CD56(+), and CD19(+) lymphocytes was compared in the graft, as well as in the peripheral blood after transplant, in patients receiving more than versus less than or equal to the median number of CD34(+) cells in PBSC (5.78 x 10(6)/kg) or in marrow (2.8 x 10(6)/kg).

RESULTS

A higher CD34(+) cell dose was associated with larger numbers of mDC in PBSC (p=0.01) and pDC in marrow grafts (p=0.004). However, neither mDC nor pDC recovery after transplant correlated with the number of CD34(+) cells infused. Finally, higher doses of CD34(+) cells appeared to negatively affect (p=0.02) the overall survival in PBSC transplantation and were associated with a trend for higher acute graft-vs-host disease in PBSC and lower acute graft-vs-host disease in marrow transplant.

CONCLUSIONS

CD34(+) cell dose correlates with the dose of different DC subsets in PBSC and marrow grafts, but it does not affect DC reconstitution after transplant. Higher doses of CD34(+) cells in PBSC, but not in marrow, seem to adversely affect survival after transplant.

Impact of CD34+ cell dose on the outcome of patients undergoing reduced-intensity-conditioning allogeneic peripheral blood stem cell transplantation

We analyzed the impact of CD34+ cell dose on the outcome of 86 patients undergoing reduced-intensity conditioning (RIC) allogeneic peripheral blood stem cell transplantation. The RIC was based on fludarabine 150 mg/m2 and melphalan 140 mg/m2 or busulphan 10 mg/kg. A median of 5.68 x 106 CD34+ cells/kg and 2.86 x 108 CD3+ cells/kg were infused. All patients receiving more than percentile 75 (p75) of CD34+ cells reached complete chimerism in T lymphocytes by days 21 to 28, compared with 44% among those receiving p75 or fewer cells (P =.046). Overall, 30.3% patients developed grade 2 to 4 acute graft-versus-host disease (aGVHD). Among 83 evaluable patients, 55.8% developed chronic GVHD (cGVHD). The dose of CD34+ cells infused did influence the development of cGVHD, with a cumulative incidence of extensive cGVHD of 74% vs 47% (P =.02) among patients receiving more than p75 CD34+ cells vs those receiving p75 or fewer. Projected overall survival (OS) and event-free survival (EFS) at 43 months were 60% and 46%, respectively. Neither the dose of CD34+ cells nor the dose of CD3+ cells infused significantly influenced OS and EFS, although among patients categorized as high-risk, 36% of those receiving p75 or fewer CD34+ cells relapsed or progressed, compared with only 9% among those receiving more than p75 CD34+ cells (P =.07). Among patients receiving p75 or fewer CD34+ cells, 36% of high-risk patients relapsed, compared with 10% of low- and intermediate-risk patients (P =.004), while relapse rates were not significantly different between both subgroups when we infused more than p75 CD34+ cells, thus indicating that infusing high doses of CD34+ cells ameliorates the negative effect of advanced disease status at transplantation. cGVHD was associated with better EFS (63% vs 16% at 43 months for patients with and without cGVHD; P <.0001) and better OS (78% vs 28% for patients with and without cGHVD; P <.001). The number of CD34+ cells infused should be tailored to prevent extensive cGVHD among patients categorized as low-risk, while high-risk patients, in whom the graft-versus-leukemia effect may determine disease outcome, should receive high doses of CD34+ cells.

Analysis of 127 stem cell donations of the regional Bone Marrow Donor Bank Europdonor Nijmegen, The Netherlands

In December 2000, the Bone Marrow DonorBank Europdonor Nijmegen in The Netherlands celebrated its tenth anniversary. We describe the organisation and activities in the first 10 years of this regional bone marrow donor bank. A concise inquiry was sent to all transplant centres who had received a graft from our donors. Response rate was 88% and data were available from 127 recipients. Three donors donated twice to different patients. Median age of the 124 donors (42 females and 82 males) was 37 years and 30 years for the 127 recipients (48 females and 79 males). Time interval between first request of a blood sample and collection of bone marrow varied from 13 to 695 days (median, 113 days). All but two donors received general anaesthesia for 25-120 min (median; 60 min). Hospital stay has been reduced to 24 h. Most donors experienced pain from the collection sites for 3-5 days. However, 9 donors (7%) suffered from pain for 2-3 weeks. All but two donors (98%) were willing to donate a second time for the same patient and 119 (96%) donors wished to remain in the register. The number of nucleated cells (NC) in the collected marrow varied from 0.2 to 8.3 x 10(8)/kg body weight of the recipient (median, 3.5 x 10(8)/kg) with 6.4-470.0 x 10(4) CFU-GM/kg body weight of the recipient (median, 18.0 x 10(4)/kg body weight). The 3-year projected probability of survival of the 127 recipients transplanted with marrow from donors provided by Bone Marrow Donor Bank Europdonor Nijmegen was 27 +/- 9% (+/-95% CI).

Addition of a low fixed number of CD3+ cells to CD34-enriched allografts: effects on engraftment, graft-versus-host disease, and survival after related and unrelated peripheral stem cell transplantation

Despite prophylaxis with immunosuppressive drugs, severe graft-versus-host disease (GVHD) remains a major cause of morbidity and mortality following allogeneic stem cell transplantation. T cell depletion of the graft has decreased incidence and severity of GVHD but has resulted in a higher incidence of graft failure and relapse. To reduce the risk of severe GVHD, but at the same time to maintain the graft-versus-tumor effect, we administered a fixed low number of 1 x 10(5) donor T cells per kilogram of body weight to recipients of CD34(+) cell-enriched allogeneic peripheral blood stem cells (PBSCs). Donor lymphocyte infusions (DLI) were then given in incremental doses when mixed chimerism persisted or signs of relapse occurred. A total of 23 patients receiving allografts from related and unrelated donors were treated according to this protocol after myeloablative or reduced intensity conditioning. One patient did not engraft and 3/20 evaluable patients developed acute (a) GVHD > or = grade II, with a corresponding estimated cumulative incidence of 15.6% (95% CI 0-30.5%). DLI (n = 13) induced aGVHD > or = II in 6 patients, but the severity of the syndrome was reduced. Overall GVHD-related mortality was low (13%). The probability of disease-free survival and overall survival at 2 years was 0.40 (95% CI 0.21-0.75) and 0.36 (95% CI 0.21-0.63). Progression-free survival and overall survival was significantly better in patients with acute or chronic myelogenous leukemia compared to patients with lymphoproliferative disorders (p = 0.002; p = 0.02). We conclude that the combination of allografts with a T cell content of about 1 x 10(5)/kg and escalating doses of DLI is a viable transplant strategy in patients with myeloid leukemias, which results in stable engraftment and a reduction of mortality from aGVHD.

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.

Decreased treatment failure in recipients of HLA-identical bone marrow or peripheral blood stem cell transplants with high CD34 cell doses

We studied the association between CD34 cell dose and transplant outcomes in 359 bone marrow (BM) and 511 peripheral blood stem cell (PBSC) transplant recipients from human leucocyte antigen (HLA)-identical siblings, reported to the International Bone Marrow Transplant Registry (IBMTR). Transplants for leukaemia were performed between 1995 and 1998. Patients were divided into those receiving below or above the median CD34+ dose, for BM (3 x 106/kg) and PBSC (6 x 106/kg) grafts respectively. Cox proportional hazards regression was used to adjust for baseline patient-, disease- and transplant-related characteristics. Analysis of the BM recipients showed that high CD34 cell dose was associated with lower transplant-related mortality [relative risk (RR) = 0.60, P = 0.033] and treatment failure (inverse of leukaemia-free survival, RR = 0.69, P = 0.032). Among PBSC recipients, high CD34 dose was associated with faster recovery of neutrophils to > 0.5 x 109/l (RR = 1.38, P < 0.001) and platelets to > 20 x 109/l (RR = 1.34, P = 0.003), lower risk of relapse (RR = 0.62, P = 0.029) and treatment failure (RR = 0.74, P = 0.03). We conclude that higher CD34 cell doses decrease treatment failure in recipients of HLA-identical sibling BM and PBSC transplants.

Higher doses of CD34+ peripheral blood stem cells are associated with increased mortality from chronic graft-versus-host disease after allogeneic HLA-identical sibling transplantation

Allogeneic peripheral blood stem cell transplantation (PBSCT) has emerged as an alternative to bone marrow transplantation. PBSCT can be associated with a higher incidence of chronic graft-versus-host disease (cGVHD). In this study, we investigated whether there was a correlation between the composition of PBSC grafts (CD34+ and CD3+ cells) and hematological recovery, GVHD, relapse, and relapse-free survival (RFS) after myeloablative HLA-identical sibling PBSCT. The evolution of 100 acute or chronic leukemia patients was analyzed. Neither hematological recovery, acute or cGVHD, nor relapse, was significantly associated with CD3+ cell dose. Increasing CD34+ stem cells was associated with faster neutrophil (P=0.03) and platelet (P=0.007) recovery. Moreover, 47 of the 78 patients evaluable for cGVHD (60%; 95% CI, 49-71%) developed extensive cGVHD. The probability of extensive cGVHD at 4 years was 34% (95% CI, 21-47%) in patients receiving a 'low' CD34+ cell dose (<8.3 x 10(6)/kg), as compared to 62% (95% CI, 48-76%) in patients receiving a 'high' CD34+ cell dose (>8.3 x 10(6)/kg) (P=0.01). At a median follow-up of 59 months, this has not translated into a difference in relapse. In patients evaluable for cGVHD, RFS was significantly higher in patients receiving a 'low' CD34+ cell dose as compared to those receiving a 'high' CD34+ cell dose (P=0.04). This difference was mainly because of a significantly higher cGVHD-associated mortality (P=0.01). Efforts to accelerate engraftment by increasing CD34+ cell dose must be counterbalanced with the risk of detrimental cGVHD.

HLA-identical stem cell transplantation: is there an optimal CD34 cell dose?

A review of the published literature, supplemented with a recent analysis of Fred Hutchinson data, has been undertaken to investigate the association of infused CD34 cell dose with various clinical outcomes after HLA-identical transplantation. Separate assessments for unrelated vs related donors and the use of bone marrow or mobilized G-PBMC have been incorporated. The three primary findings are: (1) higher CD34 dose results in better neutrophil and platelet recovery in all settings; (2) high CD34 doses (>8 x 10(6)/kg) are associated with the development of more chronic GVHD when using related G-PBMC; (3) higher CD34 dose is correlated with improved survival after bone marrow transplantation, especially with unrelated donors. This is not seen when using G-PBMC. The data suggest that the CD34 content of the graft can have a significant impact on clinical outcome after allogeneic transplantation, but optimal dose is dependent on both donor type and stem cell source.