Outcome Of Hematopoietic Stem Cell Transplantation Research Articles

VEXAS syndrome: is it more a matter of inflammation or hematopoietic clonality? A case series approach to diagnosis, therapeutic strategies and transplant management.

VEXAS syndrome is a complex hemato-inflammatory disorder, driven by somatic mutations in the UBA1 gene within hematopoietic precursor cells. It is characterized by systemic inflammation, rheumatological manifestations, and frequent association with myelodysplastic syndrome (MDS). We present a series of four VEXAS cases, all of which include concomitant MDS, each displaying distinct genetic signatures and clinical features at diagnosis, with a focus on their diagnostic and therapeutic implications. Our findings underscore the importance of extending UBA1 sequencing beyond exon 3 in cases with strong clinical suspicion. Given the rarity of non-canonical variants and the limited gene annotation, germline tissue control should be considered to differentiate somatic from germline mutations. Hematological management, including considerations for transplantation, was primarily guided by the Revised International Prognostic Scoring System (IPSS-R) for MDS due to the absence of a specific risk stratification system for VEXAS or therapy guidelines. A critical point of our discussion is the role of inflammation in the peri-transplant period; in one patient, the combination of disease-modifying antirheumatic drugs (DMARDs) and high-dose corticosteroids before transplant was crucial in controlling inflammation, resulting in a successful hematopoietic stem cell transplantation (HSCT). In contrast, uncontrolled inflammation contributed to the peri-transplant death of another patient. These cases highlight the importance of effective inflammation management in optimizing HSCT outcomes. Additionally, our study emphasizes the urgent need for specific management guidelines for VEXAS syndrome, including a comprehensive risk stratification system and optimal timing for transplantation.

Incidence and risk factors of graft failure in allogeneic hematopoietic stem cell transplantation for mucopolysaccharidosis in a nationwide pediatric cohort. A study on behalf of the Francophone Society of Bone Marrow Transplantation and Cellular Therapy.

Mucopolysaccharidosis (MPS) requires urgent treatment to prevent neurological damage. While gene therapy holds promise for effectively treating these diseases with minimal toxicity, access remains limited for most patients. Consequently, advancing allogeneic hematopoietic stem cell transplantation (HSCT) for young children is crucial. Since the 2010s, cord blood (CB) transplants with reduced-toxicity conditioning (RTC) have become the standard of care. Recent reports in France indicate a significant incidence of graft failures (GF), prompting a large-scale retrospective study from the French-speaking bone marrow transplantation society's registry, to understand GF risks, guide clinicians in selecting transplant platforms, and describe outcomes of second HSCT in young patients. This report analyses 93 children who underwent HSCT for MPS between 2000 and 2020. The GF rate was notably high (22.6% at day 100), primarily associated with the donor's HLA compatibility and the recipient's age. Well-matched CB and RTC were not found to be risk factors for GF. This study also details the procedures for second and third transplants in patients who rejected their first HSCT. In the era of RTC, CB remains a viable and expedient option for MPS transplantation.

Monocytes Matter: Impact of Monocyte Recovery on Allogeneic Hematopoietic Stem Cell Transplant Outcomes with Post-Transplantation Cyclophosphamide As Graft Versus Host Disease Prophylaxis

Monocytes Matter: Impact of Monocyte Recovery on Allogeneic Hematopoietic Stem Cell Transplant Outcomes with Post-Transplantation Cyclophosphamide As Graft Versus Host Disease Prophylaxis

Role of Myeloid-Derived Suppressor Cells (MDSCs) in the Prediction of Allogeneic Hematopoietic Stem Cell Transplantation Outcomes of Patients with Hematologic Malignancies

Role of Myeloid-Derived Suppressor Cells (MDSCs) in the Prediction of Allogeneic Hematopoietic Stem Cell Transplantation Outcomes of Patients with Hematologic Malignancies

Outcomes of children and young adults with B-cell acute lymphoblastic leukemia given blinatumomab as last consolidation treatment before allogeneic hematopoietic stem cell transplantation.

Blinatumomab has remarkable efficacy in patients with relapsed/refractory (r/r) or measurable residual disease (MRD)-positive B-cell acute lymphoblastic leukemia (B-ALL). In many patients, blinatumomab treatment is followed by allogeneic hematopoietic stem cell transplantation (HSCT). However, the influence of blinatumomab on HSCT outcomes in children and young adults (YA) remains to be fully elucidated. We conducted a single-center, retrospective analysis on patients given blinatumomab as last treatment before HSCT. Seventy-eight pediatric and YA patients were evaluated. With a median follow-up of 23.23 months, the 2-year disease-free (DFS) and overall survival (OS) probability were 72.2% and 89.2%, respectively, with a 2-year cumulative incidence (CI) of non-relapse mortality (NRM) of 2.6%. A trend toward improved 2-year DFS, but not OS, was noted in patients transplanted in first complete remission (CR1) (92.9%) compared to those in second or greater remission (CR2/3) (68.5%, p=0.18) due to a lower CI of relapse (0% vs. 29.9%, p=0.05). Among CR2/3 patients, those receiving the sequential combination of inotuzumab and blinatumomab had a significantly lower CI of relapse as compared to those who did not receive inotuzumab (9.5% vs. 40.4%, p=0.023). Relapse after HSCT occurred in 16 patients, all exhibiting CD19-positive blasts; 10 of them received anti-CD19 chimeric antigen receptor T-cell (CAR-T) therapy and 2 inotuzumab as salvage therapy, leading to a 2-year post-relapse OS of 52.7%. Our results indicate that HSCT following blinatumomab in children and YA with B-ALL is highly effective, being associated with low NRM and not affecting the efficacy of subsequent salvage immunotherapies, including CAR-T cells.

Mucosal-associated invariant T cells are functionally impaired in pediatric and young adult patients following allogeneic hematopoietic stem cell transplantation and their recovery correlates with clinical outcomes.

Mucosal-associated invariant T (MAIT) cells are innate-like T cells implicated in the response to fungal and bacterial infections. Their contribution to restoring T-cell immunity and influencing hematopoietic stem cell transplant (HSCT) outcomes remains poorly understood. We retrospectively studied MAIT-cell recovery in 145 consecutive children and young adults with hematologic malignancies undergoing allogeneic (allo)-HSCT between April 2019 and May 2022, from unrelated matched donor (MUD, N=52), with standard graft-versus-host-disease (GvHD) prophylaxis, or HLA-haploidentical (Haplo, N=93) donor after in vitro αβT/CD19-cell depletion, without post-HSCT pharmacological prophylaxis. With a median follow-up of 33 months (range, 12-49 months), overall survival (OS), disease-free survival (DFS), and non-relapse mortality (NRM) were 79.5%, 72%, and 7%, respectively; GvHD-free relapse-free survival (GRFS) was 63%, while cumulative incidence of relapse was 23%. While αβT cells were reconstituted 1-2 years post HSCT, MAIT cells showed delayed recovery and prolonged functional impairment, characterized by expression of activation (CD25, CD38), exhaustion (PD1, TIM3) and senescence (CD57) markers, and suboptimal ex vivo response. OS, DFS, and NRM were not affected by MAIT cells. Interestingly, higher MAIT cells at day +30 correlated with higher incidence of grade II-IV acute GvHD (19% vs. 7%, P=0.06). Furthermore, a greater MAIT-cell count tended to be associated with a higher incidence of chronic GvHD (cGvHD) (17% vs. 6%, P=0.07) resulting in lower GRFS (55% vs. 73%, P=0.05). Higher MAIT cells also correlated with greater cytomegalovirus (CMV) reactivation and lower late blood stream infections (BSI) (44% vs. 24%, P=0.02 and 9% vs. 18%, P=0.08, respectively). Future studies are needed to confirm the impact of early MAIT-cell recovery on cGvHD, CMV reactivation, and late BSI.

Association between positive affect, flourishing, quality of life, and psychological distress in allogeneic hematopoietic stem cell transplantation

Purpose To examine the associations between state positive psychological well-being (PPWB) constructs, mood, and quality of life (QOL) in hematopoietic stem cell transplantation (HSCT) survivors. Design The study was a secondary analysis of cross-sectional data. Sample/Methods We analyzed self-report data assessing positive affect, flourishing, QOL, depression and anxiety, and PTSD symptoms from 158 allogeneic HSCT recipients at day-100 post-transplant enrolled in supportive care studies. Findings Univariate analysis showed that factors associated with greater levels of various state PPWB constructs include older age, disability status, greater social support, and presence of graft-versus-host disease. Multivariate analysis showed that state PPWB constructs—greater levels of positive affect and flourishing—were significantly associated with better QOL and lower PTSD, anxiety, and depression symptomatology. Implications Our findings suggest that longitudinal studies are needed to examine the links between state PPWB constructs and HSCT outcomes, which may inform population specific interventions and opportunities to improve outcomes.

Soluble MICA concentrations and genetic variability of MICA and its NKG2D receptor as factors affecting Graft-versus-Host Disease development after allogeneic haematopoietic stem cell transplantation

Despite new treatment strategies, graft-versus-host disease (GvHD) remains a formidable complication after allogeneic hematopoietic stem cell transplantation (HSCT). This study aimed to investigate the impact of polymorphisms and expression of MICA and NKG2D receptor on the development of GvHD in allogeneic HSCT recipients. Soluble MICA (sMICA) concentration was measured in serum collected 30 days after transplantation and the genetic variability of MICA and NKG2D genes was evaluated. The frequency of NKG2D+NK cells was determined by flow cytometry before and (21, 30, 60 and 90 days) after transplantation. Recipients with acute GvHD grades II-IV carried the NKG2D rs1049174 C allele more frequently than controls or patients with no or mild disease. Patients with chronic GvHD had higher frequency of NKG2D expressing NK cells posttransplant, reflecting increased activity of their NK cells. Although no direct relationship between MICA SNPs and GvHD were observed, the presence of MICA rs1051792 GG genotype correlated with elevated sMICA levels and increased serum level of sMICA was associated with higher risk of chronic GvHD. Our findings suggest that sMICA concentration may serve as a potential biomarker for chronic GvHD and emphasize the impact of genetic variability of NKG2D and its surface expression on the HSCT outcome.

Insights on estetrol, the native estrogen: from contraception to hormone replacement therapy.

Estetrol (E4) is a natural estrogen that has recently emerged as new option for contraception and hormone replacement therapy (HRT). Unlike other estrogens, E4 primarily stimulates nuclear estrogen receptor alpha (ERα) and does not activate membrane ERα. For this reason, this novel estrogen has tissue-specific effects across various organs such as liver, vascular endothelium, mammary glands, brain, vagina, and uterus. The selective activation of the nuclear ERα results in distinct pharmacological properties that contribute to its unique therapeutic profile. Moreover, E4 shows minimal interaction with the hepatic cytochrome P450 enzyme system, leading to a favorable pharmacokinetic profile and a reduced potential for drug-drug interactions. Currently, E4 is commercially available in combination with drospirenone as a combined oral contraceptive and its application in HRT is undergoing late-stage clinical development. Many studies have demonstrated that E4 has a lower impact on hemostatic and metabolic parameters compared to other estrogens, potentially reducing the risk of adverse effects commonly associated with hormonal therapies such as thromboembolic events or dyslipidemia. Beyond its role in contraception and HRT, E4 shows promising therapeutic potential in other medical fields, including neuroprotection in neonatal hypoxic-ischemic encephalopathy, enhancement of hematopoietic stem cell transplantation outcomes and prostate cancer management. This review synthesizes the latest evidence on E4 primarily focusing on its pharmacological characteristics and clinical applications. The findings suggest that E4 versatility and peculiar mechanism of action may represent an important therapeutic option for a broad spectrum of medical conditions.

The outcome of haematopoietic stem cell transplantation in a patient with STAT1 gain-of-function: a case report

Background: The human signal transducer and activator of transcription 1 (STAT1) is a latent cytoplasmic transcription factor and one of seven members of the STAT family. Autosomal dominant (AD) STAT1 gain-of-function (GOF), characterized by enhanced phosphorylation of the tyrosine-701 residue and STAT1 activation, is commonly associated with chronic mucocutaneous candidiasis (CMCC), immunodeficiency, aneurysms, malignancies, and autoimmune phenomena. The best management strategies for patients with STAT1 GOF remain unclear. Typically, the standard care includes supportive treatments such as antimicrobial prophylaxis, either alone or combined with immunoglobulin replacement therapy. Biological therapies such as JAK inhibitors have been shown to alleviate symptoms of infection and autoimmune disorders in patients with STAT1 GOF mutations. However, there is a lack of long-term outcome data for JAK inhibition. Hematopoietic stem cell transplantation (HSCT) is an alternative treatment option for a subset who experience a persistent disease course despite conventional therapy. However, the effectiveness of HSCT for this condition is not yet well established. Methods: Our patient’s medical records were analyzed retrospectively, including her medical history. Results: We present the outcome of HSCT performed on a 27-year-old female with STAT1 GOF, conducted as a treatment for acute myeloid leukemia (AML). Conclusion: HSCT may serve as an alternative and potentially curative treatment for certain STAT1 GOF patients with progressive, life-threatening conditions that do not respond to conventional therapies. Additional research is needed to improve the management of these patients. Statement of Novelty: We present a novel case study of HSCT as a treatment for AML in a 27-year-old patient with STAT1 GOF, highlighting the potential for curative outcomes in progressive, life-threatening conditions unresponsive to conventional therapies. This case contributes to the limited body of evidence supporting the efficacy and challenges of HSCT in STAT1 GOF patients.

CML-073 Smoking and Depression and Hematopoietic Stem Cell Transplantation Outcome

CML-073 Smoking and Depression and Hematopoietic Stem Cell Transplantation Outcome

Smoking and Depression and Hematopoietic Stem Cell Transplantation Outcome

Smoking and Depression and Hematopoietic Stem Cell Transplantation Outcome

Decitabine-based treatment strategy improved the outcome of HSCT in JMML: a retrospective cohort study.

Pre-HSCT disease control, suboptimal long-term prognosis, and a high recurrence incidence (RI) continue to pose significant challenges for hematopoietic stem cell transplantation (HSCT) in juvenile myelomonocytic leukemia (JMML) patients. This retrospective cohort study assessed the effectiveness of a decitabine (DAC)-based protocol in JMML patients undergoing HSCT. The pre-HSCT treatment includes initial and bridging treatment. The efficacy of DAC monotherapy versus DAC combined with cytotoxic chemotherapy(C-DAC) as initial treatment was compared, followed by DAC plus FLAG (fludarabine, cytarabine, and GCSF) as bridging treatment. The HSCT regimens were based on DAC, fludarabine, and busulfan. Post-HSCT, low-dose DAC was used as maintenance therapy. The study endpoints focused on pretransplantation simplified clinical response and post-HSCT survival. There were 109 patients, including 45 receiving DAC monotherapy and 64 undergoing C-DAC treatment. 106 patients completed bridging treatment. All patients were administered planned HSCT regimens and post-HSCT treatment. The initial treatment resulted in 88.1% of patients achieving clinical remission without a significant difference between the DAC and C-DAC groups (p=0.769). Clinical remission rates significantly improved following bridging treatment (p=0.019). The 5-year overall survival, leukemia-free survival, and RI were 92.2%, 88.4%, and 8.0%, respectively. A poor clinical response to pre-HSCT treatment emerged as a risk factor for OS (hazard ratio: 9.8, 95% CI: 2.3-41.1, p=0.002). Implementing a DAC-based administration strategy throughout the pre-HSCT period, during HSCT regimens, and in post-HSCT maintenance significantly reduced relapse and improved survival in JMML patients. Both DAC monotherapy and the DAC plus FLAG protocol proved effective as pre-HSCT treatments.

Allogeneic Hematopoietic Stem Cell Transplantation in Immunodeficiency—Centromeric Instability—Facial Dysmorphism (ICF) Syndrome: an EBMT/ESID Inborn Errors Working Party Study

Immunodeficiency–Centromeric instability–Facial dysmorphism (ICF) syndrome is an inborn error of immunity characterized by progressive immune dysfunction and multi-organ disease usually treated with antimicrobial prophylaxis and immunoglobulin substitution. Allogeneic hematopoietic stem cell transplantation (HSCT) is the only curative treatment, but data on outcome are scarce. We provide a detailed description of disease characteristics and HSCT outcome in an international cohort of ICF syndrome patients. Eighteen patients (including all four genotypes) were enrolled. Main HSCT indications were infections (83%), enteropathy/failure to thrive (56%), immune dysregulation (22%) and myelodysplasia/haematological malignancy (17%). Two patients underwent pre-emptive HSCT after early diagnosis. Patients were transplanted between 2003–2021, at median age 4.3 years (range 0.5–19), after myeloablative or reduced-intensity conditioning, from matched sibling or matched family donors, matched unrelated or mismatched donors in 39%, 50% and 12% of cases respectively. Overall survival was 83% (all deaths occurred within the first 5 months post-HSCT; mean follow-up 54 months (range 1–185)). Acute GvHD occurred in 35% of patients, severe (grade III) in two (12%), while none developed chronic GvHD. At latest follow-up (median 2.2 years (range 0.1–14)), complete donor chimerism was achieved in 15/17 surviving patients. All survivors demonstrated normalized T and B cell numbers. Immunoglobulin substitution independence was achieved in all but two patients. All survivors recovered from pre-transplant infections, enteropathy/failure to thrive and immune dysregulation. All three patients transplanted at young age (≤ 3 years), after early diagnosis, survived. The favourable clinical and immunological HSCT outcome in this cohort of patients supports the timely use of this curative treatment in ICF syndrome.

EBV Reactivation and Disease in Allogeneic Hematopoietic Stem Cell Transplant (HSCT) Recipients and Its Impact on HSCT Outcomes.

The acquisition or reactivation of Epstein-Barr virus (EBV) after allogeneic Hematopoietic Stem Cell Transplant (HSCT) can be associated with complications including the development of post-transplant lymphoproliferative disorder (PTLD), which is associated with significant morbidity and mortality. A number of risk factors for PTLD have been defined, including T-cell depletion, and approaches to monitoring EBV, especially in high-risk patients, with the use of preemptive therapy upon viral activation have been described. Newer therapies for the preemption or treatment of PTLD, such as EBV-specific cytotoxic T-cells, hold promise. Further studies to help define risks, diagnosis, and treatment of EBV-related complications are needed in this at-risk population.

Advancing Allogeneic Hematopoietic Stem Cell Transplantation Outcomes through Immunotherapy: A Comprehensive Review of Optimizing Non-CAR Donor T-Lymphocyte Infusion Strategies.

Optimized use of prophylactic or therapeutic donor lymphocyte infusions (DLI) is aimed at improving clinical outcomes in patients with malignant and non-malignant hematological diseases who have undergone allogeneic hematopoietic stem cell transplantation (allo-HSCT). Memory T-lymphocytes (CD45RA-/CD45RO+) play a crucial role in immune reconstitution post-HSCT. The infusion of memory T cells is proven to be safe and effective in improving outcomes due to the enhanced reconstitution of immunity and increased protection against viremia, without exacerbating graft-versus-host disease (GVHD) risks. Studies indicate their persistence and efficacy in combating viral pathogens, suggesting a viable therapeutic avenue for patients. Conversely, using virus-specific T cells for viremia control presents challenges, such as regulatory hurdles, cost, and production time compared to CD45RA-memory T lymphocytes. Additionally, the modulation of regulatory T cells (Tregs) for therapeutic use has become an important area of investigation in GVHD, playing a pivotal role in immune tolerance modulation, potentially mitigating GVHD and reducing pharmacological immunosuppression requirements. Finally, donor T cell-mediated graft-versus-leukemia immune responses hold promise in curbing relapse rates post-HSCT, providing a multifaceted approach to therapeutic intervention in high-risk disease scenarios. This comprehensive review underscores the multifaceted roles of T lymphocytes in HSCT outcomes and identifies avenues for further research and clinical application.

Preliminary Data on SNP of Transplantation-Related Genes after Haploidentical Stem Cell Transplantation.

Background: Hematopoietic stem cell transplantation (HSCT) is one of the mainstream treatments for patients with hematologic malignancies. The matching status of human leukocyte antigen (HLA) between the donor and recipient is highly related to the outcomes of HSCT. Haploidentical HSCT (haplo-HSCT) has emerged as a type of HSCT for patients who cannot find a fully HLA-matched donor. In this study, we investigated whether the single nucleotide polymorphisms (SNPs) of the HLA-related genes and the genes encoding co-stimulatory molecules located on the non-HLA region are related to the outcomes of haplo-HSCT. Methods: The genomic DNAs of 24 patients and their respective donors were isolated from the peripheral blood obtained before performing haplo-HSCT. A total of 75 SNPs of the HLA-related genes (HCP5, NOTCH4, HLA-DOA, LTA, HSPA1L, BAG6, RING1, TRIM27, and HLA-DOB) and the genes located in the non-HLA genes involved in co-stimulatory signaling (CTLA4, TNFSF4, CD28, and PDCD1) were selected to explore their relationship with the outcomes after haplo-HSCT, including graft-versus-host disease, survival status, and relapse. Results: Our data revealed that specific donor or patient SNPs, including rs79327197 of the HLA-DOA gene, rs107822 and rs213210 of the RING1 gene, rs2523676 of the HCP5 gene, rs5742909 of the CTLA4 gene, rs5839828 and rs36084323 of the PDCD1 gene, and rs1234314 of the TNFSF4 gene, were significantly related to the development of adverse outcomes post-haplo-HSCT. Conclusions: These SNPs may play important roles in post-transplant immune response that can be considered during the selection of suitable donors.

The Impact of Microbiome Dysbiosis on Hematopoietic Stem Cell Transplantation Outcomes: A Review Article.

Microbiome dysbiosis has emerged as a critical factor influencing the outcomes of hematopoietic stem cell transplantation (HSCT). This comprehensive review delves into the intricate relationship between microbiome composition and HSCT outcomes, highlighting the mechanisms through which dysbiosis impacts engraftment, graft-versus-host disease (GVHD), infection rates, and overall survival. The gut microbiome plays a pivotal role in modulating immune responses and maintaining intestinal homeostasis, both of which are crucial for the success of HSCT. This review aims to elucidate the underlying pathways and potential therapeutic strategies to mitigate adverse outcomes associated with microbiome imbalances in HSCT patients. Integrating microbiome modulation strategies such as probiotics, prebiotics, fecal microbiota transplantation (FMT), and antibiotic stewardship into clinical practice can significantly improve patient outcomes and quality of life post-transplantation.

Patient engagement in hematopoietic stem cell transplantation and cell therapy: a survey by the EBMT patient engagement task force & transplantation complications working party.

The EBMT (European Blood and Marrow Transplantation Society) aims to connect patients, the scientific community, and other stakeholders to improve hematopoietic stem cell transplantation and cellular therapy outcomes. We performed a cross-sectional online survey to understand the perceptions regarding Patient Reported Outcomes (PROs) and Patient Active Involvement in Research (PAIR) in over 800 stakeholders (n = 813). Patients (n = 278) and health care professionals (HCPs) (n = 351) were compared. We observed high openness for EBMT PRO collection (n = 680, 84.5% across stakeholders' groups; patients n = 256, 93.1% versus HCPs n = 273, 78.4% [p < 0.001]) and PAIR (n = 702, 87.3% across stakeholder groups; patients n = 256, 92.4% versus HCPs n = 296, 85.8% [p = 0.009]), with a significantly higher proportion of patients expressing interest compared to HCPs. Priority domains for PROs data-collection identified were the assessment of symptom experience, psychosocial and cognitive functioning. The most important issues for patients specifically were the data-collection of PROs reflecting cognitive function, the option of reporting data at home, the importance of identifying actionable targets to improve their recovery, and receiving feedback on their input when participating in research projects. Our multistakeholder approach suggests an added value to embracing patient engagement in the development of meaningful research and service design within the transplantation and cellular therapy community.

The impact of MICB mismatches in unrelated haematopoietic stem cell transplantation.

MICA polymorphisms have been associated with increased incidence of acute GvHD and adverse outcome in allogeneic haematopoietic stem cell transplantation (HSCT). MICB is another expressed member of MHC class I-related chain genes and its impact on HSCT outcome is yet to be fully defined. We typed a large cohort of patients and donors for MICB polymorphisms and investigated the impact of MICB matching on outcome after unrelated HSCT. 69.2% of the patients were 10/10 human leukocyte antigen (HLA) matched and 30.8% were 9/10 HLA matched. MICB typing was performed using a short amplicon-based NGS typing assay on the Illumina MiSeq platform. Differences in proteins were considered as mismatches. MICA polymorphisms were identified as possible confounder and were therefore included as parameter in the multivariate analyses. Due to the strong linkage disequilibrium with the classical HLA-genes, sub-stratification for HLA matching status was necessary, and no effect of MICB mismatches was seen in the 10/10 HLA matched group when compared to the MICB matched cases. However, in the 9/10 HLA matched group, MICB mismatched cases showed significantly worse disease free survival (DFS), GvHD and relapse free survival (GRFS) compared to the MICB matched cases (DFS: HR 1.24, p = 0.011; GRFS: HR 1.26, p = 0.002). MICA mismatches had no impact on any outcome parameter. According to our findings, effects previously attributed to MICA differences may have been confounded by MICB polymorphisms. We show that MICB differences contribute a small but relevant effect in 9/10 HLA-matched transplantations, which in turn highlights the possible usefulness of MICB typing in donor selection among similarly suitable 9/10 matched donors, especially when HLA-B mismatches have to be accepted.