Comparison of bone marrow versus peripheral blood allogeneic hematopoietic stem cell transplantation for hematological malignancies in adults—a systematic review and meta-analysis

Photobiomodulation minimizes taste changes during hematopoietic cell transplantation: A randomized clinical trial

Prevention and treatment protocols for taste changes observed during hematopoietic cell transplantation (HCT) are not well-established. The purpose of this study was to assess the efficacy of photobiomodulation (PBM) in relieving taste changes and preventing lingual papillae atrophy. HCT patients received PBM (n = 42) on the tongue dorsum using an InGaAIP laser (660 nm, 100 mW, 1.1 W/cm2, 8.8 J/cm2). During the HCT conditioning (T0), severe neutropenia (T1), and after neutrophil engraftment (T2), taste acuity for sweet, bitter, sour, and salty solutions, and clinical appearance of lingual papillae were compared with those of a placebo group (n = 43). PBM significantly reduced hypogeusia, ageusia, and parageusia at T1 and T2, and also successfully prevented papillae atrophy during all the analyzed HCT periods. In conclusion, PBM enhanced taste acuity during HCT. The decrease in papillae atrophy indicated a potential regenerative effect of this therapy on tongue mucosa.

Alemtuzumab, Dual Graft-versus-Host Disease Prophylaxis, and Lower CD3+ T Cell Doses Equalize Rates of Acute and Chronic Graft-versus-Host Disease in Pediatric Patients Receiving Allogeneic Hematopoietic Stem Cell Transplantation with Matched Unrelated Donor Peripheral Blood Stem Cells or Bone Marrow Grafts

Data comparing hematopoietic stem cell transplantation (HSCT) using bone marrow (BM) or peripheral blood stem cell (PBSC) grafts in children after alemtuzumab-based conditioning are lacking. We investigated whether in vivo T cell depletion using alemtuzumab could reduce the risk of severe acute graft-versus-host disease (aGVHD) and chronic GVHD (cGVHD) after HSCT with matched unrelated donor (MUD) BM or PBSCs. This retrospective multicenter study included 397 children (BM group, n = 202; PBSC group, n = 195) who underwent first MUD HSCT at 9 pediatric centers in the United Kingdom between 2015 and 2019. The median age at transplantation was 7.0 years (range, .1 to 19.3 years), and the median duration of follow-up was 3.1 years (range, .3 to 7.5 years). The 3-year overall survival was 81% for the entire cohort (BM group, 80%; PBSC group, 81%). The incidence of grade II-IV aGVHD was significantly higher in the PBSC group (31%) compared to the BM group (31% versus 19%; P = .003), with no difference in the incidence of grade III-IV aGVHD (BM, 7%; PBSC, 12%; P = .17). CD3+ T cell dose >5 × 108/kg and the use of PBSCs were independent predictors of grade II-IV aGVHD. When considering CD3+ T cell dose and GVHD prophylaxis, PBSC transplantation with a calcineurin inhibitor (CNI) and mycophenolate mofetil (MMF) and a CD3+ T cell dose ≤5 × 108/kg had a comparable grade II-IV aGVHD to BM transplantation plus a CNI (20% versus 18%; P = .52). PBSC transplantation was associated with a lower incidence of cGVHD compared to BM transplantation (6% versus 11%; P = .03). Within the limits of this study, we identified a potential strategy to reduce the risk of severe GVHD in pediatric PBSC recipients that includes a combination of in vivo T cell depletion using alemtuzumab and dual GVHD prophylaxis (with a CNI and MMF) and limiting the CD3+ T cell dose to ≤5 × 108/kg.

The role of anti-thymocyte globulin in allogeneic stem cell transplantation (HSCT) from HLA-matched unrelated donors (MUD) for secondary AML in remission: a study from the ALWP /EBMT

We compared outcomes, of 1609 patients with secondary acute myeloid leukemia (sAML) undergoing allogeneic transplantation (HSCT) in first complete remission (CR1) from matched unrelated donors (MUD) from 2010 to 2021, receiving or not receiving anti-thymocyte globulin (ATG) (ATG-1308, no ATG-301). Median age was 60.9 (range, 18.5-77.8) and 61.1 (range, 21.8-75.7) years, (p = 0.3). Graft versus host disease (GVHD) prophylaxis was cyclosporin-A with methotrexate (41%) or mycophenolate mofetil (38.2%), without significant differences between groups. Day 28, engraftment (ANC > 0.5 × 109/L) was 92.3% vs 95.3% (p = 0.17), respectively. On multivariate analysis, ATG was associated with lower incidence of grade II-IV and grade III-IV acute GVHD (p = 0.002 and p = 0.015), total and extensive chronic GVHD (p = 0.008 and p < 0.0001), and relapse incidence (RI) (p = 0.039), while non-relapse mortality (NRM) did not differ (p = 0.51). Overall survival (OS), and GVHD-free, relapse-free survival (GRFS) were significantly higher in the ATG vs no ATG group, HR = 0.76 (95% CI 0.61-0.95, p = 0.014) and HR = 0.68 (95% CI 0.57-0.8, p < 0.0001), with a tendency for better leukemia-free survival (LFS), HR = 0.82 (95% CI 0.67-1, p = 0.051). The main causes of death were the original disease, infection, and GVHD. In conclusion, ATG reduces GVHD and improves LFS, OS, and GRFS in sAML patients without increasing the RI, despite sAML being a high-risk disease.

Day 4 collection of granulocyte colony-stimulating factor-mobilized HLA-matched sibling donor peripheral blood allografts demonstrates no long-term increase in chronic graft-versus-host disease or relapse rates

BACKGROUND AIMS

In a previous pilot study of HLA-matched sibling donor hematopoietic cell transplantation (HCT), the authors determined the feasibility of day 4 versus day 5 granulocyte colony-stimulating factor (G-CSF)-mobilized peripheral blood stem cell (PBSC) collection compared with a historical cohort. Given identified differences in the PBSC product (day 4 cohort with significantly lower infused total nucleated, mononuclear and CD3 cells compared with other collection cohorts), the authors performed a follow-up study to determine long-term post-HCT outcomes, including detailed characterization of chronic graft-versus-host disease (GVHD).

METHODS

This was a prospective observational study, and the authors collected data on chronic GVHD, staging, sites of involvement and treatments. Performance status, incidence of relapse, overall survival and duration of immunosuppressive therapy (IST) were also evaluated. Data were examined retrospectively. To account for differences in length of follow-up among cohorts, the authors also determined performance status and chronic GVHD staging, sites and treatment at 2 years post-HCT.

RESULTS

At 2 years post-HCT, the overall survival rate was 71.7% in the day 4 cohort compared with 61.5%, 52% and 56% in the day 5, 2-day and historical cohorts, respectively (P = 0.283). The cumulative incidence of chronic GVHD was 65.2% in the day 4 cohort versus 46.4% in the day 5 cohort, 51.1% in the 2-day cohort and 65% in the historical cohort (P = 0.26). There was no significant difference in the maximum overall stage of chronic GVHD (P = 0.513), median number of sites involved (P = 0.401) or cumulative incidence of discontinuation of IST (P = 0.32). Death from chronic GVHD was less common in the day 4 and day 5 cohorts compared with the 2-day and historical cohorts, though this did not reach statistical significance.

CONCLUSIONS

The authors' preliminary results demonstrated that collection of allogeneic matched sibling donor PBSCs on day 4 of G-CSF was feasible, reduced donor exposure to growth factor and was associated with an initial cost savings. Importantly, the authors now demonstrate that transplantation of day 4 mobilized PBSCs is not associated with any adverse outcomes post-HCT, including late effects such as chronic GVHD. Further investigation of donor G-CSF collection algorithms is merited in other HCT settings, including unrelated and mismatched related donors.

Unique Reduced-Intensity Conditioning Haploidentical Peripheral Blood Stem Cell Transplantation Protocol for Patients with Hematologic Malignancy

Reduced-intensity conditioning (RIC) haploidentical (haplo-) hematopoietic stem cell transplantation (HSCT) requires more hematopoietic progenitor and stem cells (HPSCs) to promote engraftment and immune reconstitution and needs a stronger graft-versus-leukemia effect. Peripheral blood stem cells (PBSCs) offer advantages over bone marrow; however, the use of higher-dose non-T cell-depleted (non-TCD) in vitro PBSCs may increase the occurrence of severe graft-versus-host disease (GVHD). This prospective, single-arm clinical study was performed to investigate using high-dose non-TCD in vitro PBSCs as the graft source, using fludarabine/Ara-C/busulfan (FAB) as the conditioning regimen, using rabbit antithymocyte globulin to remove T cells in vivo, and enhancing GVHD prophylaxis with an IL-2 receptor antagonist in RIC-haplo-HSCT in patients with hematologic malignancies age 50 to 70 years or <50 years with comorbidities (Hematopoietic Cell Transplantation Comorbidity Index score ≥2) classified as intermediate to high risk. The primary endpoint was day 100 acute GVHD (aGVHD). A total of 47 patients were enrolled; the median age was 52 years (range, 30 to 68 years), the median duration of follow-up was 34 months (range, 2 to 99 months), and the medium-infused doses of mononuclear cells, CD34⁺ cells, and CD3⁺ cells were 15.93 × 10⁸/kg, 8.68 × 10⁶/kg, and 5.57 × 10⁸/kg, respectively. The cumulative incidence of grade II-IV aGVHD at day 100 was 30.3% (95% confidence interval [CI], 15.9% to 44.8%), and that of grade III-IV aGVHD was 10.2% (95% CI, .6% to 19.8%). The 2-year cumulative incidence of chronic GVHD (cGVHD) was 34.9% (95% CI, 19.0% to 50.8%). The 2-year cumulative incidences of localized and extensive cGVHD were 26.1% (95% CI, 11.80% to 40.40%) and 8.7% (95% CI, 3.26% to 20.65%), respectively. The 2-year cumulative incidence of relapse was 17.3% (95% CI, 5.1% to 29.5%), the 2-year overall survival rate was 71.2% (95% CI, 57.9% to 84.5%), and the 2-year disease-free survival rate was 66.2% (95% CI, 52.1% to 80.3%). The incidence of aGVHD was not high, and the overall efficacy was good. This study demonstrates that this unique RIC-haplo-PBSC transplantation protocol was effective in treating hematologic malignancies. Nonetheless, larger prospective multicenter clinical trials and experimental studies should be performed to further confirm our findings.

Stem Cell-Based Disease Models for Inborn Errors of Immunity

The intrinsic capacity of human hematopoietic stem cells (hHSCs) to reconstitute myeloid and lymphoid lineages combined with their self-renewal capacity hold enormous promises for gene therapy as a viable treatment option for a number of immune-mediated diseases, most prominently for inborn errors of immunity (IEI). The current development of such therapies relies on disease models, both in vitro and in vivo, which allow the study of human pathophysiology in great detail. Here, we discuss the current challenges with regards to developmental origin, heterogeneity and the subsequent implications for disease modeling. We review models based on induced pluripotent stem cell technology and those relaying on use of adult hHSCs. We critically review the advantages and limitations of current models for IEI both in vitro and in vivo. We conclude that existing and future stem cell-based models are necessary tools for developing next generation therapies for IEI.

Optimizing allogeneic grafts in hematopoietic stem cell transplantation

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is widely used in the treatment of hematological diseases. It is well known that allogeneic grafts play a key role in predicting transplantation prognosis. Hematopoietic stem cells (HSCs) are a functional part of grafts and are capable of reconstructing hematopoiesis and immunity, but purified HSCs have not been identified or isolated to date. In clinical practice, allogeneic grafts have been optimized to improve transplantation outcomes. The optimized grafts are considered to engraft successfully, reconstruct immunity rapidly, and exert a graft-vs-leukemia (GVL) effect without causing severe graft-vs-host disease (GvHD). In the last several decades, considerable efforts have been made in searching for optimized grafts based on different graft manipulation approaches and different graft sources. Currently, there is no uniform standard for optimized grafts in allogeneic transplantation. In the future, sorting out the cellular elements responsible for the effects of allo-HSCT might be a research direction for further optimization of grafts. In this review, we propose the concept of optimized grafts and summarize the recent advances made in the process of optimizing grafts.

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.

Is it time to reconsider prophylactic antimicrobial use for hematopoietic stem cell transplantation? a narrative review of antimicrobials in stem cell transplantation

INTRODUCTION

Hematopoietic Stem Cell Transplantation (HSCT) is a life-saving procedure for multiple types of hematological cancer, autoimmune diseases, and genetic-linked metabolic diseases in humans. Recipients of HSCT transplant are at high risk of microbial infections that significantly correlate with the presence of graft-versus-host disease (GVHD) and the degree of immunosuppression. Infection in HSCT patients is a leading cause of life-threatening complications and mortality.

AREAS COVERED

This review covers issues pertinent to infection in the HSCT patient, including bacterial and viral infection; strategies to reduce GVHD; infection patterns; resistance and treatment options; adverse drug reactions to antimicrobials, problems of antimicrobial resistance; perturbation of the microbiome; the role of prebiotics, probiotics, and antimicrobial peptides. We highlight potential strategies to minimize the use of antimicrobials.

EXPERT OPINION

Measures to control infection and its transmission remain significant HSCT management policy and planning issues. Transplant centers need to consider carefully prophylactic use of antimicrobials for neutropenic patients. The judicious use of appropriate antimicrobials remains a crucial part of the treatment protocol. However, antimicrobials' adverse effects cause microbiome diversity and dysbiosis and have been shown to increase morbidity and mortality.

A Review of Infections After Hematopoietic Cell Transplantation Requiring PICU Care: Transplant Timeline Is Key

Despite major advances in antimicrobial prophylaxis and therapy, opportunistic infections remain a major cause of morbidity and mortality after pediatric hematopoietic cell transplant (HCT). Risk factors associated with the development of opportunistic infections include the patient's underlying disease, previous infection history, co-morbidities, source of the donor graft, preparative therapy prior to the graft infusion, immunosuppressive agents, early and late toxicities after transplant, and graft-vs.-host disease (GVHD). Additionally, the risk for and type of infection changes throughout the HCT course and is greatly influenced by the degree and duration of immunosuppression of the HCT recipient. Hematopoietic cell transplant recipients are at high risk for rapid clinical decompensation from infections. The pediatric intensivist must remain abreast of the status of the timeline from HCT to understand the risk for different infections. This review will serve to highlight the infection risks over the year-long course of the HCT process and to provide key clinical considerations for the pediatric intensivist by presenting a series of hypothetical HCT cases.

Shortened-Duration Immunosuppressive Therapy after Nonmyeloablative, Related HLA-Haploidentical or Unrelated Peripheral Blood Grafts and Post-Transplantation Cyclophosphamide

With post-transplantation cyclophosphamide (PTCy) as graft-versus-host disease (GVHD) prophylaxis, nonmyeloablative (NMA) HLA-haploidentical (haplo) and HLA-matched blood or marrow transplantation (BMT) have comparable outcomes. Previous reports have shown that discontinuation of immunosuppression (IS) as early as day 60 after infusion of a bone marrow (BM) haplo allograft with PTCy is feasible. There are certain diseases in which peripheral blood (PB) may be favored over BM, but given the higher rates of GVHD with PB, excessive GVHD is of increased concern. We report a completed, prospective single-center trial of stopping IS at days 90 and 60 after NMA PB stem cell transplantation (PBSCT). Between 12/2015-7/2018, 117 consecutive patients with hematologic malignancies associated with higher rates of graft failure after NMA conditioned BMT and PTCy, received NMA PB allografts on trial. The primary objective of this study was to evaluate the safety and feasibility of reduced-duration IS (from day 5 through day 90 in the D90 cohort and through day 60 in the D60 cohort). Of the 117 patients (median age, 64 years; range, 22 to 78 years), the most common diagnoses were myelodysplastic syndrome (33%), acute myelogenous leukemia (with minimal residual disease or arising from an antecedent disorder) (32%), myeloproliferative neoplasms (19%), myeloma (9%), and chronic lymphoblastic leukemia (7%). Shortened IS was feasible in 75 patients (64%) overall. Ineligibility for shortened IS resulted most commonly from GVHD (17 patients), followed by early relapse (11 patients), nonrelapse mortality (NRM) (7 patients), patient/ physician preference (4 patients) or graft failure (3 patients). Of the 57 patients in the D90 cohort, 33 (58%) stopped IS early as planned, and among the 60 patients in the D60 cohort, 42 (70%) stopped IS early as planned. The graft failure rate was 2.6%. After IS cessation, the median time to diagnosis of grade II-IV acute GVHD was 21 days in the D90 cohort and 32 days in the D60 cohort, with almost all cases developing within 40 days. Approximately one-third of these patients resumed IS. All outcome measures were similar in the 2 cohorts and our historical outcomes with 180 days of IS. The cumulative incidence of grade III-IV acute GVHD was low, 2% in the D90 cohort and 7% in the D60 cohort. The incidence of severe chronic GVHD at 2 years was 9% in the D90 cohort and 5% in the D60 cohort. The 2-year overall survival was 67% for both the D90 and D60 cohorts. The 2-year progression-free survival was 47% for the D90 cohort and 52% for the D60 cohort, and the GVHD-free, relapse-free survival was <35% for both cohorts. These data suggest that reduced-duration IS in patients undergoing NMA PBSCT with PTCy is feasible and has an acceptable safety profile. © 2020 American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc.

Role of Stem-Cell Transplantation in Leukemia Treatment

Stem cells (SCs) play a major role in advanced fields of regenerative medicine and other research areas. They are involved in the regeneration of damaged tissue or cells, due to their self-renewal characteristics. Tissue or cells can be damaged through a variety of diseases, including hematologic and nonhematologic malignancies. In regard to this, stem-cell transplantation is a cellular therapeutic approach to restore those impaired cells, tissue, or organs. SCs have a therapeutic potential in the application of stem-cell transplantation. Research has been focused mainly on the application of hematopoietic SCs for transplantation. Cord blood cells and human leukocyte antigen-haploidentical donors are considered optional sources of hematopoietic stem-cell transplantation. On the other hand, pluripotent embryonic SCs and induced pluripotent SCs hold promise for advancement of stem-cell transplantation. In addition, nonhematopoietic mesenchymal SCs play their own significant role as a functional bone-marrow niche and in the management of graft-vs-host disease effects during the posttransplantation process. In this review, the role of different types of SCs is presented with regard to their application in SC transplantation. In addition to this, the therapeutic value of autologous and allogeneic hematopoietic stem-cell transplantation is assessed with respect to different types of leukemia. Highly advanced and progressive scientific research has focused on the application of stem-cell transplantation on specific leukemia types. We evaluated and compared the therapeutic potential of SC transplantation with various forms of leukemia. This review aimed to focus on the application of SCs in the treatment of leukemia.

BM is preferred over PBSCs in transplantation from an HLA-matched related female donor to a male recipient

The use of granulocyte colony-stimulating factor-mobilized peripheral blood stem cells (PBSCs) and sex-mismatched hematopoietic cell transplantation (HCT), especially with female donors and male recipients (FtoM), is known to be associated with an increased risk of chronic graft-versus-host disease (GVHD) compared with transplantation with bone marrow (BM). This raises the question of whether the use of PBSCs in FtoM HCT might affect allogeneic responses, resulting in fatal complications. Using a Japanese transplantation registry database, we analyzed 1132 patients (FtoM, n = 315; MtoF, n = 260; sex-matched, n = 557) with standard-risk diseases who underwent HCT with an HLA-matched related donor without in vivo T-cell depletion between 2013 and 2016. The impact of PBSC vs BM on transplantation outcomes was separately assessed in FtoM, MtoF, and sex-matched HCT. Overall survival (OS) and nonrelapse mortality (NRM) at 2 years post-HCT were significantly worse in patients with PBSCs vs those with BM in FtoM HCT (2-year OS, 76% vs 62%; P = .0084; 2-year NRM, 10% vs 21%; P = .0078); no differences were observed for MtoF or sex-matched HCT. Multivariate analyses confirmed the adverse impact of PBSCs in FtoM HCT (hazard ratio [HR] for OS, 1.91; P = .025; HR for NRM, 3.70; P = .0065). In FtoM HCT, patients with PBSCs frequently experienced fatal GVHD and organ failure. In conclusion, the use of PBSCs in FtoM HCT was associated with an increased risk of NRM in the early phase, resulting in inferior survival. This suggests that, when we use female-related donors for male patients in HCT, BM may result in better outcomes than PBSCs.

Mobilization and collection of cells in the hematologic compartment for cellular therapies: Stem cell collection with G-CSF/plerixafor, collecting lymphocytes/monocytes

An essential and influential first step in all cellular therapies is collecting donor or patient cells. In hematopoietic progenitor cell transplantation, autologous or allogeneic hematopoietic progenitor cells (HPCs) are collected from either the bone marrow or the peripheral blood. Peripheral blood collection by apheresis requires mobilization with chemotherapy, granulocyte colony stimulating factor (G-CSF), plerixafor, or a combination. The modalities of mobilization and collection each carry a unique set of risks and benefits for both the donor and the recipient. In other types of cell therapy, most notably chimeric antigen receptor T cells, lymphocytes or monocytes are collected from the peripheral blood. The risks of collecting these cells by apheresis are similar to HPCs, but less is known about the composition, timing and qualitative cell characteristics which contribute to an optimal collection. Here, we review the mobilization and collection of HPCs and the collection of lymphocytes and monocytes. Donor safety is of primary importance when collecting material for any type of cell therapy. Every aspect of mobilization and collection can be studied and potentially optimized to improve patient outcomes.

Pre-transplantation Risks and Transplant-Techniques in Haematopoietic Stem Cell Transplantation for Acute Leukaemia

BACKGROUND

The role of conditioning intensity and stem cell source on modifying pre-transplantation risk in allogeneic haematopoietic stem cell transplantation (HSCT) is a matter of debate, but crucial when benchmarking centres.

METHODS

This Retrospective, multicenter exploratory-validation analysis of 9103 patients, (55.5% male, median age 50 years; 1-75 years range) with an allogeneic HSCT between 2010 and 2016 from a matched sibling (N = 8641; 95%) or matched unrelated donor (N = 462; 5%) for acute myeloid (N = 6432; 71%) or acute lymphoblastic (N = 2671; 29%) leukaemia in first complete remission, and reported by 240 centres in 30 countries to the benchmark database of the European Society for Blood and Marrow Transplantation (EBMT) searched for factors associated with use of transplant techniques (standard N = 6375;70% or reduced intensity conditioning N = 2728;30%, respectively bone marrow N = 1945;21% or peripheral blood N = 7158;79% as stem cell source), and their impact on outcome.

FINDINGS

Treatment groups differed significantly from baseline population (p < 0.001), and within groups regarding patient-, disease-, donor-, and centre-related pre-transplantation risk factors (p < 0.001); choice of technique did depend on pre-transplantation risk factors and centre (p < 0.001). Probability of overall survival at 5 years decreased systematically and significantly with increasing pre-transplantation risk score (score 2 vs 0/1 HR: 1·2, 95% c.i. [1·1-1·.3], p = 0.002; score 3 vs 0/1 HR: 1·5, 95% c.i. [1·3-1·7], p < 0.001; score 4/5/6 vs 0/1 HR: 1·9, 95% c.i. [1·6-2·2], p < 0.001) with no significant differences between treatment groups (likelihood ratio test on interaction: p = 0.40). Overall survival was significantly associated with selection steps and completeness of information (p < 0.001).

INTERPRETATION

Patients' pre-transplantation risk factors determine survival, independent of transplant techniques. Transplant techniques should be regarded as centre policy, not stratification factor in benchmarking. Selection criteria and completeness of data bias outcome. Outcomes may be improved more effectively through better identifying pre-transplantation factors as opposed to refinement of transplant techniques.

FUNDING

The study was funded by EBMT.

Hematopoietic stem cell transplantation for adults with Philadelphia chromosome-negative acute lymphoblastic leukemia in first remission: a position statement of the European Working Group for Adult Acute Lymphoblastic Leukemia (EWALL) and the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation (EBMT)

Allogeneic hematopoietic stem cell transplantation (HSCT) in first complete remission is a standard of care for adult patients with Philadelphia chromosome (Ph)-negative acute lymphoblastic leukemia (ALL) and high risk of relapse. However, the stratification systems vary among study groups. Inadequate response at the level of minimal residual disease is the most commonly accepted factor indicating the need for alloHSCT. In this consensus paper on behalf of the European Working Group for Adult Acute Lymphoblastic Leukemia and the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation, we summarize available evidence and reflect current clinical practice in major European study groups regarding both indications for HSCT and particular aspects of the procedure including the choice of donor, source of stem cells and conditioning. Finally, we propose recommendations for daily clinical practice as well as for planning of prospective trials.

Feasibility and cost analysis of day 4 granulocyte colony-stimulating factor mobilized peripheral blood progenitor cell collection from HLA-matched sibling donors

BACKGROUND

Guidelines recommend treatment with 4-5 days of granulocyte colony-stimulating factor (G-CSF) for optimal donor peripheral blood progenitor cell (PBPC) mobilization followed by day 5 collection. Given that some autologous transplant recipients achieve adequate collection by day 4 and the possibility that some allogeneic donors may maximally mobilize PBPC before day 5, a feasibility study was performed evaluating day 4 allogeneic PBPC collection.

METHODS

HLA-matched sibling donors underwent collection on day 4 of G-CSF for peripheral blood (PB) CD34⁺ counts ≥0.04 × 10⁶/mL, otherwise they underwent collection on day 5. Those with inadequate collected CD34⁺ cells/kg recipient weight underwent repeat collection over 2 days. Transplant and PBPC characteristics and cost analysis were compared with a historical cohort collected on day 5 per our prior institutional algorithm.

RESULTS

Of the 101 patient/donor pairs, 50 (49.5%) had adequate PBPC collection on day 4, with a median PB CD34⁺ cell count of 0.06 × 10⁶/mL. Day 4 donors were more likely to develop bone pain and require analgesics. Median collected CD34⁺ count was significantly greater, whereas total nucleated, mononuclear and CD3⁺ cell counts were significantly lower, at time of transplant infusion for day 4 versus other collection cohorts. There were no significant differences in engraftment or graft-versus-host disease. Cost analysis revealed 6.7% direct cost savings for day 4 versus historical day 5 collection.

DISCUSSION

Day 4 PB CD34⁺ threshold of ≥0.04 × 10⁶/mL identified donors with high likelihood of adequate PBPC collection. Day 4 may be the optimal day of collection for healthy donors, without adverse effect on recipient transplant outcomes and with expected cost savings.

Immune reconstitution following hematopoietic stem cell transplantation using different stem cell sources

Introduction: Adequate immune reconstitution post-HSCT is crucial for the success of transplantation, and can be affected by both patient- and transplant-related factors. Areas covered: A systematic literature search in PubMed, Scopus, and abstracts of international congresses is performed to investigate immune recovery posttransplant. In this review, we discuss the pattern of immune recovery in the post-transplant period focusing on the impact of stem cell source (bone marrow, peripheral blood stem cells, and cord blood) on immune recovery and HSCT outcome. We examine the impact of serotherapy on immune reconstitution and the need to tailor dosing of serotherapy agents when using different stem cell sources. We discuss new techniques being used particularly with cord blood and haploidentical grafts to improve immune recovery in each scenario. Expert opinion: Cord blood T cells provide a unique CD4+ biased immune reconstitution. Initial studies using targeted serotherapy with cord grafts showed improved immune recovery with limited alloreactivity. Two competing haploidentical approaches have developed in recent years including TCRαβ/CD19 depleted grafts and post-cyclophosphamide haplo-HSCT. Both approaches have comparable survival rates with limited alloreactivity. However, delayed immune reconstitution is still an ongoing problem and could be improved by modified donor lymphocyte infusions from the same haploidentical donor.

New Strategy of Acute Graft-vs-Host Disease: Investigation of a Reduced Dose of Antithymocyte Globulin in Haploidentical Hematopoietic Stem Cell Transplantation

Graft-vs-host disease (GVHD) is one of the biggest challenges in haploidentical hematopoietic stem cell transplantation. Antithymocyte globulins (ATGs) are widely used to overcome GVHD, but excessive immunosuppression increases the chances of relapse and infection following transplantation. No defined standard of the appropriate dose of ATG usage is recognized. The study included 11 patients who were treated with a reduced dose of ATG to prevent GVHD in haploidentical hematopoietic stem cell transplantation. A reduced dose of ATG-Thymoglobulin (total dose of 5 mg/kg) was used in the pretreatment protocol for 2 consecutive days. All patients had successful transplantation. The median time of neutrophil engraftment was 12 days. All chimerism tests passed on day 30, 60, and 90 post transplantation. None of the patients had acute GVHD, while only 2 patients had I to II degree chronic GVHD (18.2%). No transplantation-related deaths were observed. The current findings suggest that the reduced dose of ATG can effectively prevent the incidence of acute GVHD in haploidentical hematopoietic stem cell transplantation.

Allogeneic hematopoietic stem cell transplantation with myeloablative conditioning for adult cerebral X-linked adrenoleukodystrophy

The adult cerebral form of X-linked adrenoleukodystrophy (ACALD), an acute inflammatory demyelinating disease, results in a rapidly progressive neurodegeneration, typically leading to severe disability or death within a few years after onset. We have treated 15 men who had developed ACALD with allogeneic hematopoietic stem cell transplantation (HSCT) from matched donors after myeloablative conditioning with busulfan and cyclophosphamide. All patients engrafted and 11 survived (estimated survival 73 ± 11%), 8 with stable cognition and 7 of them with stable motor function (estimated event-free survival 36 ± 17%). Death after transplantation occurred within the first year after HSCT and was caused either primarily by infection (N = 3) or due to disease progression triggered by infection (N = 1). Patients with minor myelopathic symptoms (N = 4) or with no or mild cerebral symptoms pre-transplant (N = 7) had an excellent outcome. In contrast, no patient with major neurological symptoms associated with an extensive involvement of pyramidal tract fibres in the internal capsule (N = 5) survived without cognitive deterioration. Notably, early leukocyte recovery was associated with dismal outcome for yet unknown reasons. All 10 tested survivors showed a reduction of plasma hexacosanoic acid (C26:0) in the absence of Lorenzo's oil. Over time, the event-free survival could be improved from 2 out of 8 patients (25%) before 2013 to 5 out of 7 patients (71%) thereafter. Therefore, allogeneic HSCT appears to be a suitable treatment option for carefully selected ACALD patients when transplanted from matched donors after myeloablative, busulfan-based conditioning.

The Concentration of Total Nucleated Cells in Harvested Bone Marrow for Transplantation Has Decreased over Time

Bone marrow (BM) is an essential source of hematopoietic stem cell grafts for many allogeneic hematopoietic cell transplant (HCT) recipients, including adult patients (for specific diseases and transplantation strategies) and the majority of pediatric recipient. However, since the advent of granulocyte colony-stimulating factor-mobilized peripheral blood stem cell (PBSC) grafts, there has been a significant decrease in the use of BM in HCT, thought to be due mainly to the increased logistical challenges in harvesting BM compared with PBSCs, as well as generally no significant survival advantage of BM over PBSCs. The decreased frequency of collection has the potential to impact the quality of BM harvests. In this study, we examined >15,000 BM donations collected at National Marrow Donor Program centers between 1994 and 2016 and found a significant decline in the quality of BM products, as defined by the concentration of total nucleated cells (TNCs). The mean TNC concentration in BM donations dropped from 21.8 × 10⁶ cells/mL in the earliest era (1994 to 1996) to 18.7 × 10⁶ cells/mL in the most recent era (2012 to 2016) (means ratio, .83; P < .001). This decline in BM quality was seen despite the selection of more donors perceived to be optimal (eg, younger and male). Multivariate regression analysis showed that higher-volume centers (performing >30 collections per era) had better-quality harvests with higher concentrations of TNCs collected. In conclusion, we have identified a significant decrease in the quality of BM collections over time, and lower-volume collection centers had poorer-quality harvests. In this analysis, we could not elucidate the direct cause for this finding, suggesting the need for further studies to investigate the key factors responsible and to explore the impact on transplant recipients.

Impact of anti-thymocyte globulin on results of allogeneic peripheral blood stem cell transplantation for patients with Philadelphia-positive acute lymphoblastic leukaemia: An analysis by the Acute Leukemia Working Party of the EBMT

BACKGROUND

Anti-thymocyte globulin (ATG) is widely used to prevent graft-versus-host disease (GVHD) after allogeneic peripheral blood stem cell transplantation (alloPBSCT). The goal of this study was to retrospectively assess the effect of ATG on outcomes in the setting of Philadelphia chromosome-positive acute lymphoblastic leukaemia (Ph+ ALL).

METHODS

In the analysis, 1170 adult patients undergoing alloPBSCT from human leucocyte antigen-matched sibling or unrelated donors in the first complete remission between 2007 and 2016 were included. ATG was used in 429/575 (75%) and 121/595 (20%) patients transplanted from unrelated or sibling donors, respectively.

RESULTS

The incidence of chronic GVHD was 35% for patients treated with ATG compared with 52% in those not receiving ATG (p < 0.001), while the rate of extensive chronic GVHD was 16% and 36%, respectively (p < 0.001). The probability of survival free from GVHD and relapse (GRFS) was 42% and 32%, respectively (p = 0.002). In a multivariate model, the use of ATG was associated with reduced risk of overall chronic GVHD (hazard ratio [HR] = 0.52, p < 0.001) and extensive chronic GVHD (HR = 0.46, p < 0.001). It was also associated with better GRFS (HR = 0.77, p = 0.007), despite increased risk of relapse (HR = 1.41, p = 0.02). No significant effect was found with regard to the risk of non-relapse mortality and overall mortality.

CONCLUSIONS

The use of ATG for patients with Ph+ ALL undergoing alloPBSCT is associated with reduced risk of chronic GVHD without impact on survival and therefore, could be considered. However, increased risk of relapse suggests the need for strict monitoring of minimal residual diseases and appropriate interventions after transplantation.

Prevention of relapse after allogeneic hematopoietic cell transplantation by donor and cell source selection

Allogeneic hematopoietic cell transplantation (HCT) is the most established form of cancer immunotherapy and has been successfully applied for the treatment and cure of otherwise lethal neoplastic blood disorders. Cancer immune surveillance is mediated to a large extent by alloreactive T and natural killer (NK) cells recognizing genetic differences between patient and donor. Profound insights into the biology of these effector cells has been obtained over recent years and used for the development of innovative strategies for intelligent donor selection, aiming for improved graft-versus-leukemia effect without unmanageable graft-versus-host disease. The cellular composition of the stem cell source plays a major role in modulating these effects. This review summarizes the current state-of the-art of donor selection according to HLA, NK alloreactivity and stem cell source.

Comparable Outcomes of Allogeneic Peripheral Blood versus Bone Marrow Hematopoietic Stem Cell Transplantation in Major Thalassemia: A Multivariate Long-Term Cohort Analysis

Allogeneic hematopoietic stem cell transplantation (HSCT) currently is the only available curative option for transfusion-dependent thalassemia. Peripheral blood is a more convenient source for HSCT in comparison with bone marrow. Information about the relative success of transplantation with these 2 graft sources would help physicians and patients choose between them. The aim of this study was to evaluate the pros and cons of using peripheral blood instead of bone marrow as the graft source in thalassemia transplantation. We analyzed the transplant results of 567 transfusion-dependent thalassemia patients who received a transplant between 1998 and 2015 considering their stem cell source as a comparative variable. In multivariate Cox analysis the survival advantage for bone marrow compared with peripheral blood was not significant after adjusting for sex, age, and hepatic fibrosis presence. Rejection incidence was significantly lower in patients who used peripheral blood as their graft source. Acute and chronic graft-versus-host disease were more frequent in peripheral blood transplants, but the difference was not statistically significant. This study shows that peripheral blood could be an alternative stem cell source in patients undergoing allogeneic HSCT for thalassemia.

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.

Haploidentical versus matched donor stem cell transplantation for patients with hematological malignancies: a systemic review and meta-analysis

We compared the safety and efficacy of haploidentical stem cell transplantation (haplo-SCT) to matched donor SCT (matched-SCT) in treating hematological malignancies. The Medline, Cochrane, EMBASE, and Google Scholar databases were searched through 21 June 2017 using the search term "(hematological disease) AND matched AND (haploidentical OR haplo-identical OR haplo identical OR haplo transplantation OR haplo transplant OR haplo-SCT OR haplo-HSCT OR haplo-HCT)." Twenty-five studies enrolling 11,359 patients (haplo-SCT: 2677; matched-SCT: 8682) were included. The primary outcomes were acute and chronic graft-versus-host disease (GVHD), non-relapse mortality, and 1-year cumulative incidence of relapse. Haplo-SCT was associated with similar risks as matched-SCT for all primary endpoints. Subgroup analysis of patients who received a matched-SCT from a related donor revealed that patients who received haplo-SCT had a lower risk of acute GVHD. Among patients who received reduced-intensity conditioning (RIC), those who received haplo-SCT had a higher risk of acute grade II-IV GVHD and non-relapse mortality than did patients who received a matched-SCT from a related or unrelated donor. Haplo-SCT should continue to be considered as a safe and effective transplant option when a matched donor is unavailable, but it may not be suitable for patients who receive RIC.

Bone marrow versus peripheral blood as a graft source for haploidentical donor transplantation in adults using post-transplant cyclophosphamide-A systematic review and meta-analysis

BACKGROUND

Peripheral-blood (PB) and bone marrow (BM) are both widely used in hematopoietic stem cell transplantation (HSCT). However, it is unclear whether PB or BM produces a more satisfactory outcome in haploidentical HSCT, particularly for patients using post-transplant cyclophosphamide (PTCy), which is the standard therapy. However, to date, no meta-analysis focusing on this issue has been published.

METHODS

We systematically searched PubMed, MEDLINE, Web of Science, the Cochrane Library and the ClinicalTrials.gov website for studies regarding the use of BM or PB in haploidentical HSCT for hematological malignancies in adults using PTCy. Data were analyzed using Open Meta-Analyst statistical software.

RESULTS

Fourteen studies were extracted including four comparative retrospective reports and ten single-arm reports, with a total of 1759 patients received PTCy haploidentical HSCT (462 patients received PBSCT, 1297 patients received BMT). The pooled outcomes of comparative retrospective studies showed significantly higher incidence of grade III-IV acute graft-versus-host disease (GVHD) (OR = 1.741, 95%CI 1.032-2.938), incidence of grade IIIV acute GVHD (OR = 1.778, 95%CI 1.314, 2.406) and engraftment rate (OR = 1.843, 95%CI 1.066-3.185) in the PB group. No significant differences were found on the incidence of relapse, 2-year overall survival (OS) and disease-free survival (DFS), acute IIIV GVHD and chronic GVHD between PBSCT or BMT.

CONCLUSION

The efficacy of PB is not inferior to BM for patients undergoing PTCy haploidentical HSCT with regard to primary outcomes, including OS, DFS, NRM and relapse. However, with regards to convenience and pain relief, PB graft is suitable for haploidentical HSCT, but with a higher risk of acute GVHD.

Anti-thymocyte globulin improves survival free from relapse and graft-versus-host disease after allogeneic peripheral blood stem cell transplantation in patients with Philadelphia-negative acute lymphoblastic leukemia: An analysis by the Acute Leukemia Working Party of the EBMT

BACKGROUND

Mobilized peripheral blood stem cells are currently the predominant source of grafts for allogeneic transplantation (allogeneic peripheral blood stem cell transplantation [allo-PBSCT]), although, in comparison with bone marrow, their use is associated with an increased risk of chronic graft-versus-host disease (cGVHD). Attempts to reduce the incidence of cGVHD include the addition of anti-thymocyte globulin (ATG) to the pretransplant conditioning regimen.

METHODS

The goal of this retrospective study was to analyze the effect of ATG on allo-PBSCT outcomes for adults with Philadelphia-negative acute lymphoblastic leukemia (Ph-neg ALL). The primary endpoint was survival free from relapse, grade 3 to 4 acute graft-versus-host disease (aGVHD), and cGVHD (ie, graft-versus-host disease-free/relapse-free survival [GRFS]). Nine-hundred twenty-four patients who underwent unmanipulated allo-PBSCT in their first complete remission between 2007 and 2016 were included. ATG was used in 97 of the 494 transplants from matched sibling donors (20%) and in 307 of the 430 transplants from human leukocyte antigen-matched (8 of 8 loci) unrelated donors (71%).

RESULTS

The use of ATG was an independent factor for an improved chance of GRFS (hazard ratio [HR], 0.70; P = .0009). Furthermore, it was associated with a reduced risk of both grade 2 to 4 (HR, 0.66; P = .005) and grade 3 to 4 aGVHD (HR, 0.58; P = .03). Similarly, its addition reduced the incidence of both total (HR, 0.45; P < 10^-5 ) and extensive cGVHD (HR, 0.30; P < 10^-5 ) as well as nonrelapse mortality (HR, 0.58; P = .01). No significant effect was found with respect to leukemia-free or overall survival. However, an increased risk of relapse was noted for those who received ATG (HR, 1.40; P = .04).

CONCLUSIONS

Patients with Ph-neg ALL treated with allo-PBSCT benefit from the use of ATG in terms of improved GRFS. Its use may, therefore, be considered in this setting. Cancer 2018;124:2523-33. © 2018 American Cancer Society.

Network geometry of evidence from randomised controlled trials addressing donor selection and source of haematopoietic progenitor cells used in allogeneic transplantation: a systematic scoping review

BACKGROUND AND METHODS

A scoping review of randomised controlled trials (RCTs) addressing source of cells and choice of donor for allogeneic haematopoietic cell transplantation (HCT) was performed to create a network of best evidence that allows us to identify new potential indirect comparisons for the strategic development of future studies that connect to the existing evidence network.

RESULTS

A total of 19 eligible RCTs (2589 total patients) were identified. Nine studies (1566 patients) compared clinical outcomes following the use of peripheral blood progenitor cells (PBPCs) with bone marrow (BM) from matched related donors (eight studies) or matched unrelated donors (one study). The remaining studies compared BM or PBPCs with various methods of BM stimulation or manipulation (six studies), compared different methods of surface molecule-based selection and/or depletion of grafts (two studies) or compared the optimal number of units for paediatric cord blood transplantation (two studies). No published RCTs compared different types of donors. The geometry of the evidence network was analysed to identify opportunities for potential novel indirect comparisons and to identify opportunities to expand the network. Few indirect comparisons are currently feasible due to small sample size and heterogeneity in patient diagnoses and demographics between treatment nodes in the network.

CONCLUSION

More RCTs that enrol greater numbers of similar patients are needed to leverage the current evidence network concerning donor choice and source of cells used in allogeneic HCT.

Dynamical system modeling to simulate donor T cell response to whole exome sequencing-derived recipient peptides: Understanding randomness in alloreactivity incidence following stem cell transplantation

Quantitative relationship between the magnitude of variation in minor histocompatibility antigens (mHA) and graft versus host disease (GVHD) pathophysiology in stem cell transplant (SCT) donor-recipient pairs (DRP) is not established. In order to elucidate this relationship, whole exome sequencing (WES) was performed on 27 HLA matched related (MRD), & 50 unrelated donors (URD), to identify nonsynonymous single nucleotide polymorphisms (SNPs). An average 2,463 SNPs were identified in MRD, and 4,287 in URD DRP (p<0.01); resulting peptide antigens that may be presented on HLA class I molecules in each DRP were derived in silico (NetMHCpan ver2.0) and the tissue expression of proteins these were derived from determined (GTex). MRD DRP had an average 3,670 HLA-binding-alloreactive peptides, putative mHA (pmHA) with an IC50 of <500 nM, and URD, had 5,386 (p<0.01). To simulate an alloreactive donor cytotoxic T cell response, the array of pmHA in each patient was considered as an operator matrix modifying a hypothetical cytotoxic T cell clonal vector matrix; each responding T cell clone’s proliferation was determined by the logistic equation of growth, accounting for HLA binding affinity and tissue expression of each alloreactive peptide. The resulting simulated organ-specific alloreactive T cell clonal growth revealed marked variability, with the T cell count differences spanning orders of magnitude between different DRP. Despite an estimated, uniform set of constants used in the model for all DRP, and a heterogeneously treated group of patients, higher total and organ-specific T cell counts were associated with cumulative incidence of moderate to severe GVHD in recipients. In conclusion, exome wide sequence differences and the variable alloreactive peptide binding to HLA in each DRP yields a large range of possible alloreactive donor T cell responses. Our findings also help understand the apparent randomness observed in the development of alloimmune responses.

How to build an allogeneic hematopoietic cell transplant unit in 2016: Proposal for a practical framework

Allogeneic hematopoietic cell transplantation is part of the standard of care for many hematological diseases. Over the last decades, significant advances in patient and donor selection, conditioning regimens as well as supportive care of patients undergoing allogeneic hematopoietic cell transplantation leading to improved overall survival have been made. In view of many new treatment options in cellular and molecular targeted therapies, the place of allogeneic transplantation in therapy concepts must be reviewed. Most aspects of hematopoietic cell transplantation are well standardized by national guidelines or laws as well as by certification labels such as FACT-JACIE. However, the requirements for the construction and layout of a unit treating patients during the acute phase of the transplantation procedure or at readmission for different complications are not well defined. In addition, the infrastructure of such a unit may be decisive for optimized care of these fragile patients. Here we describe the process of planning a transplant unit in order to open a discussion that could lead to more precise guidelines in the field of infrastructural requirements for hospitals caring for people with severe immunosuppression.

Clinical-associated characteristics and microbiological features of bloodstream nontyphoidal salmonella infection in adult patients receiving allogeneic hematopoietic stem cell transplantation

Bloodstream nontyphoidal salmonella (NTS) infection is rare, but its associated characteristics and microbiological features in immunocompromised patients are worth paying attention to, particularly for those receiving allogeneic hematopoietic stem cell transplantation (SCT). No studies so far have analyzed post-transplant bloodstream NTS infection. Therefore, we reviewed 423 adult patients undergoing allogeneic hematopoietic SCT from 2003 to 2014. Nine out of four hundred twenty-three patients (2.13%) developed post-transplant bloodstream NTS infection, including two patients who had subsequent or combined metastatic infections. The median age at SCT was 35 years (interquartile range, 29-46) among the nine patients with bloodstream NTS infection. Male patients were predominant (78%). The median onset of bloodstream NTS infection was at 315 days after SCT (range, 207-629). Multivariate analysis revealed that extensive chronic graft-versus-host disease (GVHD) (OR 8.054, p = 0.003) and nonmyeloablative transplant conditioning (OR 4.604, p = 0.037) were significant associated characteristics for NTS infection. Currently, there are no published data analyzing and exploring post-transplant bloodstream NTS infections in adult allogeneic hematopoietic SCT. Our study determined the associated characteristics and microbiological features for this infection.

Donor Selection for Allogenic Hemopoietic Stem Cell Transplantation: Clinical and Ethical Considerations

Allogenic hematopoietic progenitor cell transplantation (allo-HSCT) is an established treatment for many diseases. Stem cells may be obtained from different sources: mobilized peripheral blood stem cells, bone marrow, and umbilical cord blood. The progress in transplantation procedures, the establishment of experienced transplant centres, and the creation of unrelated adult donor registries and cord blood banks gave those without an human leucocyte antigen- (HLA-) identical sibling donor the opportunity to find a donor and cord blood units worldwide. HSCT imposes operative cautions so that the entire donation/transplantation procedure is safe for both donors and recipients; it carries with it significant clinical, moral, and ethical concerns, mostly when donors are minors. The following points have been stressed: the donation should be excluded when excessive risks for the donor are reasonable, donors must receive an accurate information regarding eventual adverse events and health burden for the donors themselves, a valid consent is required, and the recipient's risks must be outweighed by the expected benefits. The issue of conflict of interest, when the same physician has the responsibility for both donor selection and recipient care, is highlighted as well as the need of an adequate insurance protection for all the parties involved.

Immunothérapie et greffe de cellules souches hématopoïétiques allogéniques

IMMUNOTHERAPY AND ALLOGENEIC STEM CELLS TRANSPLANTATION

Allogeneic stem cell transplantations represent perfect example of immunotherapy. Its positive aspects are due to the graft versus tumor effect. Unfortunately, this therapeutic advantage is usually associated with graft versus host effects. While the mechanism of these two graft reactions remain unclear, this is possible to modulate these immunologic effects. The type of conditioning regimen, the source of donor and the use of donor cells after the transplantation may influence the toxicity and the tumor response, leading to a better optimization of the procedure. This paper is presenting all the parameters which may contribute to improve allogeneic stem cell transplantations.

Milestones of Hematopoietic Stem Cell Transplantation - From First Human Studies to Current Developments

Since the early beginnings, in the 1950s, hematopoietic stem cell transplantation (HSCT) has become an established curative treatment for an increasing number of patients with life-threatening hematological, oncological, hereditary, and immunological diseases. This has become possible due to worldwide efforts of preclinical and clinical research focusing on issues of transplant immunology, reduction of transplant-associated morbidity, and mortality and efficient malignant disease eradication. The latter has been accomplished by potent graft-versus-leukemia (GvL) effector cells contained in the stem cell graft. Exciting insights into the genetics of the human leukocyte antigen (HLA) system allowed improved donor selection, including HLA-identical related and unrelated donors. Besides bone marrow, other stem cell sources like granulocyte-colony stimulating-mobilized peripheral blood stem cells and cord blood stem cells have been established in clinical routine. Use of reduced-intensity or non-myeloablative conditioning regimens has been associated with a marked reduction of non-hematological toxicities and eventually, non-relapse mortality allowing older patients and individuals with comorbidities to undergo allogeneic HSCT and to benefit from GvL or antitumor effects. Whereas in the early years, malignant disease eradication by high-dose chemotherapy or radiotherapy was the ultimate goal; nowadays, allogeneic HSCT has been recognized as cellular immunotherapy relying prominently on immune mechanisms and to a lesser extent on non-specific direct cellular toxicity. This chapter will summarize the key milestones of HSCT and introduce current developments.

Optimal graft source for allogeneic hematopoietic stem cell transplant: bone marrow or peripheral blood?

Peripheral blood (PB), compared with bone marrow graft, has higher stem cell content, leads to faster engraftment and is more convenient for collection. Consequently, the use of PB graft has significantly increased in recent years. Although the use of PB graft is acceptable or even preferred to bone marrow graft in matched related donor allogeneic transplant due to a possibility of improved survival, PB graft increases the risk of chronic graft-versus-host disease and associated long-term toxicities in the setting of matched unrelated donor allogeneic transplant. In haploidentical transplant, mitigation of graft-versus-host disease with the use of post-transplant cyclophosphamide is a hypothesis-generating possibility; however, available studies have significant limitations to draw any definite conclusion.

Prognostic Factors on the Graft-versus-Host Disease-Free and Relapse-Free Survival after Adult Allogeneic Hematopoietic Stem Cell Transplantation

The cure of hematologic disorders by allogeneic hematopoietic stem cell transplantation (HSCT) is often associated with major complications resulting in poor outcome, including graft-versus-host disease (GVHD), relapse, and death. A novel composite endpoint of GVHD-free/relapse-free survival (GRFS) in which events include grades 3-4 acute GVHD, chronic GVHD requiring systemic therapy, relapse, or death is censored to completely characterize the survival without mortality or ongoing morbidity. In this regard, studies attempting to identify the prognostic factors of GRFS are quite scarce. Thus, we reviewed 377 adult patients undergoing allogeneic HSCT between 2003 and 2013. The 1- and 2-year GRFS were 40.8% and 36.5%, respectively, significantly worse than overall survival and disease-free survival (log-rank p < 0.001). European Group for Blood and Marrow Transplantation (EBMT) risk score > 2 (p < 0.001) and hematologic malignancy (p = 0.033) were poor prognostic factors for 1-year GRFS. For 2-year GRFS, EBMT risk score > 2 (p < 0.001), being male (p = 0.028), and hematologic malignancy (p = 0.010) were significant for poor outcome. The events between 1-year GRFS and 2-year GRFS predominantly increased in relapsed patients. With prognostic factors of GRFS, we could evaluate the probability of real recovery following HSCT without ongoing morbidity.

Risk of graft-versus-host disease with rituximab-containing conditioning regimens in allogeneic hematopoietic stem cell transplant

Graft-versus-host disease represents a major cause of morbidity and mortality in allogeneic hematopoietic stem cell transplant patients. There is growing evidence that B lymphocytes may play a role in the pathogenesis of acute graft-versus-host disease. The purpose of this retrospective cohort study was to evaluate the efficacy of rituximab-containing conditioning regimens in decreasing graft-versus-host disease in allogeneic hematopoietic stem cell transplant patients who received standardized tacrolimus-based graft-versus-host disease prophylaxis regimens. Patients were divided into two cohorts, based on the presence (RTX, n = 54) or absence (No-RTX, n = 105) of rituximab in the conditioning regimen and were matched 1:2 for major graft-versus-host disease risk factors. The incidence of grade II-IV acute graft-versus-host disease was not different between the two groups (37% vs. 26%, p = 0.147). When restricting the analysis to recipients of peripheral blood hematopoietic stem cell transplants, the RTX group had a higher incidence of grade II-IV acute graft-versus-host disease, relapse, or death prior to day 100 (55% vs. 36%, p = 0.037). The median time to the onset of acute graft-versus-host disease was no different between the RTX and No-RTX groups (67 vs. 74 days, respectively, p = 0.141). Inhibition of antigen presentation by B cells with rituximab-based conditioning regimens does not appear to reduce the incidence of acute graft-versus-host disease in allogeneic hematopoietic stem cell transplant recipients.

Comparable outcomes between autologous and allogeneic transplant for adult acute myeloid leukemia in first CR

Although allogeneic hematopoietic stem cell transplantation from an HLA-matched sibling donor (MSD) is a potentially curative post-remission treatment for adults with acute myeloid leukemia (AML) in their first CR, transplant-related morbidity and mortality remains a major drawback. We retrospectively compared the outcomes of patients who underwent autologous peripheral blood stem cell transplantation (auto-PBSCT; n=375) with those who underwent allogeneic bone marrow transplantation (allo-BMT; n=521) and allo-PBSCT (n=380) from MSDs for adults with AML/CR1, in which propensity score models were used to adjust selection biases among patients, primary physicians and institutions to overcome ambiguity in the patients' background information. Both the multivariate analysis and propensity score models indicated that the leukemia-free survival rate of auto-PBSCT was not significantly different from that of allo-BMT (hazard ratio (HR), 1.23; 95% confidence interval (CI), 0.92 to 1.66; P=0.16) and allo-PBSCT (HR, 1.13; 95% CI, 0.85-1.51; P=0.40). The current results suggest that auto-PBSCT remains a promising alternative treatment for patients with AML/CR1 in the absence of an available MSD.

Molecular Chimeric Recipient Precursor T Cells Promote Cardiac Allograft Survival in Mice

BACKGROUND

Molecular chimerism has become a potential method to induce donor-specific transplant tolerance. We researched the prolongation of cardiac allograft survival by recipient mouse molecular chimeric precursor T cells (pre-T cells) or hematopoietic stem cells (HSCs) infusion in vivo.

METHODS

The donor C57BL/6 mouse MHC-I gene (H-2K(b) and H-2D(b) gene) were amplified by RT-PCR. The identified recipient BALB/c mouse pre-T cells and HSCs were transduced by the pMSCVneo retroviral vector of C57BL/6 mouse MHC-I gene (pMSCVneo-H-2D(b)/H-2K(b)). Then the molecular chimeric cells were transfused back to the BALB/c mice. Allogeneic T-lymphocyte proliferation was assessed in mixed lymphocyte reactions (MLR). A mouse model of heterotopic abdominal heart transplantation was performed to evaluate survival times and histological grade of acute rejection at 7 days after transplantation.

RESULTS

BALB/c mice molecular chimeric pre-T cells and HSCs were cultured successfully after pMSCV-H-2D(b)/H-2K(b) transduction. After the molecular chimeric pre-T cell treatment, the result of MLR showed that the stimulating index of allogeneic T lymphocyte had a statistically significant decrease, which also exhibited a significant reduction after molecular chimeric HSC treatment. The survival time of cardiac allograft was prolonged after chimeric pre-T cell or HSC infusion; meanwhile, pathologic rejection grade decreased significantly. Nevertheless, molecular chimeric pre-T cells exhibited a longer median survival time.

CONCLUSION

The molecular chimeric recipient mouse pre-T cell or HSC infusion reduced spleen T cells' response to allogeneic T cells in vitro and delayed cardiac allograft rejection in vivo. Pre-T cells have more advantages than HSCs on the prolongation of mouse cardiac allograft survival.

Time-dependent effects of clinical predictors in unrelated hematopoietic stem cell transplantation

Hematopoietic stem cell transplantation is a multifactorial process. Some of the predictors exhibit time-dependent effects. We present a systematic analysis and description of selected clinical predictors influencing outcome in a time-dependent manner based on an analysis of registry data from the German Registry for Stem Cell Transplantation. A total of 14,951 patients with acute myeloid leukemia, acute lymphocytic leukemia, myelodysplastic syndrome and non-Hodgkin lymphoma transplanted with peripheral blood stem cells or bone marrow grafts were included. Multivariate Cox regression models were tested for time-dependent effects within each diagnosis group. Predictors not satisfying the proportional hazards assumption were modeled in a time-dependent manner, extending the Cox regression models. Similar patterns occurred in all diagnosis groups. Patients with a poor Karnofsky performance score (<80) had a high risk for early mortality until day 139 following transplantation (HR 2.42, CI: 2.19-2.68; P<0.001) compared to patients with a good Karnofsky performance score (80-100). Afterwards the risk reduced to HR 1.43, CI: 1.25-1.63; P<0.001. A lower mortality risk was found for patients after conditioning treatment with reduced intensity until day 120 post transplant (HR: 0.81 CI: 0.75-0.88; P<0.001). After this, a slightly higher risk could be shown for these patients. Similarly, patients who had received a PBSC graft exhibited a significantly lower mortality risk until day 388 post transplantation (HR 0.79, CI: 0.73-0.85; P<0.001), reversing to a significantly higher risk afterwards (HR 1.23, CI: 1.08-1.40; P=0.002). Integrating time dependency in regression models allows a more accurate description and quantification of clinical predictors to be made, which may help in risk assessment and patient counseling.