HLA-compatible Donor Research Articles

Use of intermediate-resolution deceased donor molecular typing in organ allocation systems could increase the fraction of HLA-compatible donor offers

Use of intermediate-resolution deceased donor molecular typing in organ allocation systems could increase the fraction of HLA-compatible donor offers

Real-World Challenges of Haplo-Identical Hematopoietic Stem Cell Transplant in a Developing Country: A Single Center Experience.

Hematopoietic stem cell transplant (HSCT) is potentially, the sole curative option for many malignant and non-malignant hematological disorders. Finding a human leukocyte antigen (HLA) compatible donor remains one of the limiting factors, hampering the utilization of HSCT. However, the introduction of post-transplant cyclophosphamide (PTCy) has improved the outcomes of haploidentical transplants making it a suitable option for patients lacking HLA-compatible donors. We collected data from 44 patients who underwent haplo-identical allogeneic stem cell transplants at the Armed Forces Bone Marrow Transplant Center/National Institute of Blood and Marrow Transplant (AFBMTC/NIBMT) from the year 2015 to 2022. The diseases were divided into three categories, i.e., bone marrow failure (BMF) syndromes, hematological malignancies (HM) and miscellaneous (Misc) groups. Median age at transplant was 18 (01-39) years. Transplant indications included aplastic anemia (AA) in 21 (47.7%) cases, 15 (34.1%) HM, and eight (18.2%) cases falling in the Misc groups. A maximum number of graft failures occurred in the BMF group; primary graft failure in 07 (33.3%) cases and secondary graft failure in four (19%) cases, (p-value < 0.05). Acute graft versus host disease (aGVHD) grade II-IV occurred in nine (20.5%) cases while chronic graft versus host disease (cGVHD) occurred in 10 (22.7%) cases. Cytomegalovirus (CMV) reactivation was seen in 31 (70.5%) cases. Maximum CMV reactivation was seen in HM group 13 (86.6%) cases, (p-value < 0.05) as compared to BMF (71.4%) and Misc groups (37.5%). Post-transplant cyclophosphamide (PTCy) based regimens, early neutrophil engraftment, and patients with GVHD had better survival outcomes (p-value < 0.05) overall survival (OS), and relapse-free survival (RFS). and GVHD-free relapse-free survival (GFRS) were significantly better in cases with early neutrophil engraftment. OS of the study cohort was 50% while disease-free survival (DFS) and GFRS were 45.5% and 36.4%, respectively.

Donor KIR genotype based outcome prediction after allogeneic stem cell transplantation: no land in sight.

Optimizing natural killer (NK) cell alloreactivity could further improve outcome after allogeneic hematopoietic cell transplantation (alloHCT). The donor's Killer-cell Immunoglobulin-like Receptor (KIR) genotype may provide important information in this regard. In the past decade, different models have been proposed aiming at maximizing NK cell activation by activating KIR-ligand interactions or minimizing inhibitory KIR-ligand interactions. Alternative classifications intended predicting outcome after alloHCT by donor KIR-haplotypes. In the present study, we aimed at validating proposed models and exploring more classification approaches. To this end, we analyzed samples stored at the Collaborative Biobank from HLA-compatible unrelated stem cell donors who had donated for patients with acute myeloid leukemia (AML) or myelodysplastic neoplasm (MDS) and whose outcome data had been reported to EBMT or CIBMTR. The donor KIR genotype was determined by high resolution amplicon-based next generation sequencing. We analyzed data from 5,017 transplants. The median patient age at alloHCT was 56 years. Patients were transplanted for AML between 2013 and 2018. Donor-recipient pairs were matched for HLA-A, -B, -C, -DRB1, and -DQB1 (79%) or had single HLA mismatches. Myeloablative conditioning was given to 56% of patients. Fifty-two percent of patients received anti-thymocyte-globulin-based graft-versus-host disease prophylaxis, 32% calcineurin-inhibitor-based prophylaxis, and 7% post-transplant cyclophosphamide-based prophylaxis. We tested several previously reported classifications in multivariable regression analyses but could not confirm outcome associations. Exploratory analyses in 1,939 patients (39%) who were transplanted from donors with homozygous centromeric (cen) or telomeric (tel) A or B motifs, showed that the donor cen B/B-tel A/A diplotype was associated with a trend to better event-free survival (HR 0.84, p=.08) and reduced risk of non-relapse mortality (NRM) (HR 0.65, p=.01). When we further dissected the contribution of B subtypes, we found that only the cen B01/B01-telA/A diplotype was associated with a reduced risk of relapse (HR 0.40, p=.04) while all subtype combinations contributed to a reduced risk of NRM. This exploratory finding has to be validated in an independent data set. In summary, the existing body of evidence is not (yet) consistent enough to recommend use of donor KIR genotype information for donor selection in routine clinical practice.

Implementación de la PCR digital para el diagnóstico prenatal no invasivo de la enfermedad de células falciformes. Estudio piloto

Sickle Cell Disease (SCD) is one of the most prevalent autosomal recessive disease, affecting over 600,000 newborns globally each year. In Spain, the Spanish Registry of Hemoglobinopathies (REHem) has registered 1142 cases. Despite improvements in treatments, prophylaxis, and vaccines, it remains a chronic condition requiring lifelong care. Allogeneic transplantation is the only cure, contingent upon the availability of an HLA-compatible donor. SCD is considered a rare disease in some population, resulting from a mutation of a single nucleotide in codon 6 GAG&gt;GTG (HBB: c.20A&gt;T) of the β-globin gene, producing hemoglobin S (HbS), altering the shape of red blood cells and obstructing circulation, leading to severe complications in multiple organs. Heterozygous individuals (βS/βA) have the ‘sickle cell trait,’ typically asymptomatic. Homozygotes experience symptomatic disease, with chronic and acute infarctions in organs and tissues, episodes of intense pain, cerebral infarctions, splenomegaly, massive hemolytic episodes, and acute chest syndrome, causing a risk of premature death increasing the threat of premature mortality. Prenatal diagnosis provides expecting couples with information about the fetus’s genetic health, enabling informed decision-making. Although conventional techniques are invasive and carry risks, Non-Invasive Prenatal Diagnosis (NIPD) has been developed using cell free fetal DNA (cffDNA) in maternal blood to determine the fetus’s genotype. However, the co-presence of maternal DNA and cffDNA, along with the low concentration of the latter, has been a challenge in non-invasive studies. We present the results of a pilot study where the use of digital PCR (dPCR) has been established for NIPD of SCD, a highly sensitive technique allowing the detection of mutations in low-frequency samples, presenting itself as a safe alternative for SCD diagnosis.

Preclinical Assessment for Gene Addition Strategy in Familial Hemophagocytic Lymphohistiocytosis Related to Munc 13-4 Deficiency

Introduction: Familial Hemophagocytic Lymphohistiocytosis (FHL) comprises a group of rare genetic disorders with defect cytotoxicity in T and NK cells predisposing to severe hyperinflammation with the clinical hallmark of the Hemophagocytic LymphoHistiocytosis (HLH) syndrome. The uncontrolled proliferation of activated T-CD8 lymphocytes and macrophages infiltrates lymphoid tissues, bone marrow, and multiple organs including the brain. Thus, if untreated full-scale FHL is usually fatal. FHL3 is due to mutations in the UNC13D gene coding for Munc 13-4 protein, one of the components of the perforin-dependent cytotoxicity apparatus. This condition accounts for 30% to 35 % of all genetic cases of HLH. Hematopoietic stem and progenitor cell (HSPC) transplantation, which is the only curative treatment for FHL3 to date, remains difficult even when a compatible donor is available because of the patients' critical inflammatory background. In this context, gene therapy could be a promising therapeutic option, especially for those patients without HLA-compatible donor. Method: The feasibility and efficacy of gene addition strategy for FHL3 have been previously demonstrated in mouse models. We then translated this approach to human cells using a third-generation self-inactivated lentivirus vector pseudo-typed with a conventional vesicular stomatitis virus-G (VSVG) expressing a codon-optimized UNC13D gene under the transcriptional control of EF1 alpha (LV-EF1a-UNC13D). HSPC or CD3+ T-cells were transduced with a GMP-like-grade LV-EF1a-UNC13D lentiviral vector. We studied the restoration of cytotoxic function. Results: Our GMP transduction protocol led to efficient transcription of optimized mRNA codon and expression of Munc 13-4 protein as evidenced by RT qPCR and western blot, respectively. Interestingly, we show restored cytotoxicity activity after CD34+ differentiation toward CD3+ T-cells and NK cells. The vector copy number is compatible with a clinical approach. In vivo experiments are ongoing to validate the absence of genotoxicity in this setting. Discussion conclusion: Our results support the feasibility and efficacy of UNCD13D gene transfer into hematopoietic stem and progenitor cells or T cells from Munc 13-4 deficient patients. Alternatively, gene therapy of HSPCs could be combined with transduced autologous T-cells infusion. The first attempts regarding this option are encouraging. UNC13D gene addition strategy could dramatically improve the care of FHL3 patients lacking an HLA-genoidentical donor.

Clonal Hematopoiesis Is Common in Unrelated Stem Cell Donors but Has No Impact on Patient Outcome after Hematopoietic Stem Cell Transplantation

Introduction. Clonal hematopoiesis (CH) has been associated with increased mortality mainly due to associations with cardiovascular diseases and hematologic cancer. Previous studies with predominantly related stem cell donors suggest that donor CH modulates graft-versus-host reactions and may augment graft-versus-leukemia effects after allogeneic hematopoietic cell transplantation (alloHCT). The impact of donor CH in the setting of unrelated alloHCT remains to be determined. To address this question, we initiated a joint study of the Transplant Complications Working Party of EBMT and DKMS. Patients and Methods. Donor samples from the time of stem cell donation were taken from the Collaborative Biobank. Patient baseline and outcome data were retrieved from the EBMT registry. Unrelated donor-recipient pairs were selected for a minimum donor age of 35 years. CH analysis was performed with an error-corrected ultra-deep NGS assay for 45 genes with a median sensitivity of 0.2% variant allele frequency (VAF). Accuracy of low frequency CH findings was checked by cross validation with an orthogonal assay. The primary objective was to assess the impact of donor CH on overall survival (OS). Major secondary endpoints were the risk of relapse/progression and non-relapse mortality (NRM), cumulative incidences of acute and chronic GVHD and event-free survival (EFS). All endpoints were evaluated with (cause-specific) multivariable Cox regression models. Adjustment factors were patient and donor age, diagnosis, disease risk index, Karnofsky performance status, conditioning intensity, GVHD-prophylaxis, graft source, HLA-match, sex match and CMV match. We did not adjust for multiple testing. Results. Data from 2584 unrelated donor-recipient pairs were analyzed. Median patient follow-up after alloHCT was 60 months. The median donor age was 46 years (range, 39-61 years). The median patient age was 54 years (range, 0-79 years). Indications for alloHCT were AML (44%), ALL (10%), MDS (10%), MPN (6%), B-cell lymphoma (6%), Multiple Myeloma (5%), CML 3%, inherited disorders (3%), CLL 2% and other (13%). Transplantations were performed between 2005 and 2018. In vivo or ex vivo T-cell depletion (TCD) was used in 81% of transplants, PTCY in 5% and no TCD in 14%. Mutations in DNMT3A, TET2, and ASXL1 defined CH most frequently. The distribution of donor CH across leukemia driver genes was comparable to previous reports (Panel A). With 0.2% (2%) VAF cutoffs, rates of DNMT3A-mutations were 19% (2%) among donors younger than 41 years compared to 37% (6%) among donors aged 55 years and higher. Corresponding rates for 0.2% (2%) VAF cutoffs for total CH were 38% (4%) among donors younger than 41 years compared to 67% (14%) among donors aged 55 years and higher. We tested systematically increasing VAF cutoffs (≥0.2% versus &amp;lt;0.2%, ≥1% versus &amp;lt;1%, ≥2% versus &amp;lt;2%, ≥5% versus &amp;lt;5%, and ≥5% versus &amp;lt;0.2%) for DNMT3A-CH and total CH for associations with clinical endpoints. Panel B shows results for multivariable regression analyses for total donor CH. Although we observed trends towards increased mortality and inferior EFS for some cutoffs, no incremental impact of donor CH with higher VAF was found and no systematic changes of the risk for GVHD and relapse/progression were observed. Conclusions. We conclude that donor CH has no significant impact on the risk for GVHD, relapse and survival in the context of HLA-compatible unrelated donor alloHCT with GVHD-prophylaxis based predominantly on T-cell depletion with ATG.

5 years DKMS Chile: approach, results and impact of the first unrelated stem cell donor center in Chile.

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is performed worldwide to treat blood cancer and other life-threatening blood disorders. As successful transplantation requires an HLA-compatible donor, unrelated donor centers and registries have been established worldwide to identify donors for patients without a family match. Ethnic minorities are underrepresented in large donor registries. Matching probabilities are higher when donors and patients share the same ethnic background, making it desirable to increase the diversity of the global donor pool by recruiting donors in new regions. Here, we report the establishment and the first 5 years of operation of the first unrelated stem cell donor center in Chile, a high-income country in South America with a population of over 19 million. We used online and in-person donor recruitment practices through patient appeals and donor drives in companies, universities, the armed forces, and public services. After confirmatory typing donors were subjected to medical work-up and cleared for donation. We recruited almost 170,000 donors in 5 years. There were 1,488 requests received for confirmatory typing and donor availability checks, of which 333 resulted in medical work-up, leading to 194 stem cell collections. Products were shipped to Chile (48.5%) and abroad. Even when the COVID-19 pandemic challenged our activities, the number of donors recruited and shipped stem cell products remained steady. In Chile there was an almost 8-fold increase in unrelated donor transplantation activity from 16 procedures in 2016-2018 to 124 procedures in 2019-2021, mainly for pediatric patients following the center's establishment. We estimate that 49.6% of Chilean patients would find at least one matched unrelated donor in the global DKMS donor pool. Establishing a DKMS donor center in Chile has significantly increased donor availability for Chilean patients and contributed to an increase of unrelated donor stem cell transplant activity.

Donor Selection for Allogeneic Hematopoietic Cell Transplantation.

In Germany, each year over 3000 patients with malignant and non-malignant hematologic and systemic diseases are treated by allogeneic hematopoietic cell transplantation (HCT). Genetic donor-recipient disparities, especially those concerning variable human leukocyte antigens (HLA), mediate both an immunotherapeutic effect and the risk of damage to healthy tissues ("graft-versus-host disease"). The adoption of evidence-based strategies for donor selection has been crucial for the continuous improvement of survival rates after allogeneic HCT, with over 50% of patients transplanted for standard indications-such as early-stage acute myeloid leukemia-alive at three years post-transplant. The PubMed database was selectively searched for literature on immunogenetic and clinical factors relevant to allogeneic HCT, as part of the process of establishing a German consensus statement on HCT donor selection. The most important factor in donor selection is a match for the five major HLA loci (HLA-A, -B, -C, -DR, -DQ), either in genetically HLA-identical siblings or in unrelated but fully HLA-compatible donors from international registries. Additional selection criteria for the latter include compatibility for the HLA-DP locus, donor age and sex, cytomegalovirus serostatus, and blood group. Related donors identical for only 50% of the HLA genes (haploidentical donors) as well as unrelated donors with a single HLA mismatch are both valid alternatives although they are associated with an up to 10% higher risk of mortality. The refinement of donor selection strategies has been instrumental for the continuous improvement of patient survival rates after allogeneic HCT witnessed over the past decades. An interdisciplinary approach to donor selection based on up-to-date scientific evidence is crucial for optimizing patient outcomes.

ABO-adjusted calculated panel reactive antibody (cPRA): A unified metric for immunologic compatibility in kidney transplantation

Implementation of the kidney allocation system in 2014 greatly reduced access disparity due to human leukocyte antigen (HLA) sensitization. To address persistent disparity related to candidate ABO blood groups, herein we propose a novel metric termed "ABO-adjusted cPRA," which simultaneously considers the impact of candidate HLA and ABO sensitization on the same scale. An ethnic-weighted ABO-adjusted cPRA value was computed for 190 467 candidates on the kidney waitlist by combining candidate's conventional HLA cPRA with the remaining fraction of HLA-compatible donors that are ABO-incompatible. Consideration of ABO sensitization resulted in higher ABO-adjusted cPRA relative to conventional cPRA by HLA alone, except for AB candidates since they are not ABO-sensitized. Within cPRA Point Group=99%, 43% of the candidates moved up to ABO-adjusted cPRA Point Group=100%, though this proportion varied substantially by candidate blood group. Nearly all O and most B candidates would have elevated ABO-adjusted cPRA values above this policy threshold for allocation priority, but relatively few A candidates displayed this shift. Overall, ABO-adjusted cPRA more accurately measures the proportion of immune-compatible donors compared with conventional HLA cPRA, especially for highly sensitized candidates. Implementation of this novel metric could enable the development of allocation policies permitting more ABO-compatible transplants without compromising equity.

Updated Analysis on the Outcomes of Children with Acute Leukemia (AL) Receiving an Alpha/Beta T and B-Cell Depleted HLA-Haploidentical Hematopoietic Stem Cell Transplantation (TBdepl-haploHSCT)

Background: We previously reported (Locatelli et al., Blood 2017) that TBdepl-haploHSCT is a suitable and effective option for children with AL lacking an HLA-compatible donor and/or needing an urgent allograft. This type of transplant is characterized by a low incidence of both acute and chronic graft-versus-host disease (GvHD) and by low non-relapse mortality (NRM), translating into survival outcomes comparable to those of patients transplanted from an HLA-compatible donor. Here we report an update on a cohort of 213 children with AL of our study, with a minimum follow-up of 180 days after the allograft. Patients and methods: Between October 2010 and January 2022, 213 children with AL received TBdepl-haploHSCT from an HLA-partially matched relative at Ospedale Pediatrico Bambino Gesù in Rome, Italy. All patients were in morphological complete remission (CR) and were prepared to TBdepl-haploHSCT using a fully-myeloablative conditioning regimen including a combination of total body irradiation (TBI) and/or cytotoxic drugs. All patients received also anti-T-lymphocyte globulin (ATLG) before transplantation (12 mg/kg total dose, from days -5 to day -3) to modulate bi-directional donor/recipient alloreactivity and rituximab (200 mg/sqm) on day -1 to prevent post-transplantation EBV-induced lymphoproliferative disorders (PTLD). No patient received any post-transplant pharmacological GvHD prophylaxis. Data were analyzed as of July 15, 2022. Results: Table 1 reports details on characteristics of patients included in the analysis. The median follow-up of surviving patients is 47.6 months (range: 6 months - 11.7 years). Two hundred and eight patients (98% of the total number) engrafted with a median time to neutrophil and platelet recovery of 13 (range 9-24) and 11 (range 7-23) days, respectively. Only 5 patients experienced graft failure; all were rescued with a second allograft. Eleven out of the 213 patients (5%) died of transplant-related complications (4 because of idiopathic pneumonia, 2 each because of disseminated adenovirus infection and thrombotic microangiopathy and 1 each of cardiac insufficiency, combined CMV/rhinovirus pneumonia and sepsis from Pseudomonas aeruginosa), the 5-year cumulative incidence of NRM being 5.2% (95% CI, 2.8-8.8). Forty-four patients relapsed at a median time of 192 days (range 56-1711) after HSCT, the 5-year cumulative incidence of relapse being 22.7% (95% CI, 16.9-29.2). Cumulative incidence of grade II-III acute GvHD was 14.7% (95% CI 10.6-20.3). Three patients and 1 developed gut and liver GvHD, respectively, while for all other patients skin was the sole organ involved. Fourteen out of the 193 patients at risk developed chronic GvHD, in all cases of limited severity, the cumulative incidence of this complication being 8.1% (95% CI 4.8-13.3). The 10-year probability of overall and leukemia-free survival (LFS) were 75.4 (95% CI 68.6-80.9) and 71.6% (95% CI 64.4-77.6), respectively. In univariate analysis, disease status at transplantation (CR1 vs CR2 vs CR>3), use of TBI during the preparative regimen and age at transplant above the median value (9.5 years) were associated with better patient's outcome, mainly because of a reduced incidence of relapse. Notably, among TBI-based regimens, the use of thiotepa and fludarabine was associated with an improved DFS as compared to other combinations (82.4% vs 63.9%, p=0.01). In a multivariable model for LFS including also gender and type of disease, only TBI (hazard ratio (HR) 0.38 (95% CI, 0.17-0.85, p=0.01) and disease status at HSCT (HR 1.72 (95% CI, 1.05-2.79, p=0.02) remained statistically significant. The 10-year GvHD/relapse-free survival was 65.1% (95% CI 57.7-71.4). The median CD3+ cell count on day +30, +90, +180 and +360 were 140, 185, 533 and 1058 /mcl, respectively. Conclusions: TBdepl-haploHSCT is becoming a widespread haplo platform for pediatric patients affected by both malignant and non-malignant disorders. This cohort of homogeneously treated patients, the largest reported so far with a median follow-up of almost 4 years, confirm once more the effectiveness and safety of this approach. Furthermore, this analysis identified subgroups of patients (e.g., those in CR>3) for whom post-transplant strategies aimed at reducing the risk of relapse (the main cause of treatment failure) are desirable. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Incidence of Common Herpesviruses in Colonic Mucosal Biopsies Following Hematopoietic Stem Cell Transplantation.

Intestinal complications are common after allogeneic hematopoietic stem cell transplantation (allo-HSCT). However, only scarce data concern herpesvirus incidence in the colonic mucosa post-HSCT. Our purpose was to assess the frequency and clinical significance of cytomegalovirus (CMV), Epstein-Barr virus (EBV), human herpesvirus type 6 (HHV6), and herpes simplex virus (HSV) in the colonic mucosa post-HSCT. The study group included 119 patients of different ages, mostly with leukemias and lymphomas, subjected to allo-HSCT from haploidentical related (48%) or HLA-compatible donors (52%). In total, 155 forceps biopsies of the colonic mucosa were taken in cases of severe therapy-resistant intestinal syndrome post-HSCT. Most samples were taken from the descending, sigmoid, and transverse colon. Intestinal GVHD or local infections were assessed clinically and by histology. EBV, CMV, HSV, and HHV6 were tested in colonic mucosal lysates with commercial PCR assays. HSV was found in &lt;8% of colonic samples, along with high HHV6 and CMV positivity (up to 62% and 35%, respectively) and a higher EBV incidence at 5-6 months post-HSCT (35%). For CMV and EBV, significant correlations were revealed between their rates of detection in blood and colonic mucosa (r = 0.489 and r = 0.583; p &lt; 0.05). No significant relationships were found between the presence of herpesviruses and most patients' characteristics. EBV positivity in colonic samples was correlated with delayed leukocyte and platelet recovery post-HSCT. Higher EBV frequency in the colonic mucosa was found in deceased patients (56% versus 21%, p = 0.02). The correlations among EBV positivity in the colon, lethality rates and delayed hematopoietic reconstitution suggest some relationship with systemic and local EBV reactivation post-transplant.

PB1843: ACUTE MYELOID LEUKEMIA WITH PHILADELPHIA CHROMOSOME: EXPERIENCE OF SFAX HEMATOLOGY DEPARTMENT

Background: Acute myeloid leukemia with Philadelphia chromosome (AML Ph+) is recently been listed in the 2016 revised World Health Organization (WHO) classification of myeloid malignancies as a provisional entity. Aims: A rare entity whose treatment is not yet established. we are studying the characteristics of a series of patients with AML Phi+. Methods: It’s a retrospective study over 15 years (2005-2019) which includes patients with AML Phi+, diagnosed and treated in the clinical hematology department of Hedi Chaker Sfax Hospital / TUNISIA. We are interested in studying the clinical and biological characteristics, the different treatments received and overall survival (OS). Known patients followed for Chronic Myeloid Leukemia (CML) and who are transformed into blast phase are excluded. Results: Among 264 cases of newly diagnosed AML, we collected 5 cases of AML Phi+ (1.8%). The average age was 43 years (range: 34 to 54). Sex-ratio was 1.5. On initial examination, splenomegaly was found in all cases. WBC counts less than 10 G/l, from 10 to 100 G/L and more than 100 G/L were observed respectively in 20, 40 and 40% of cases. Myelemia was found in 4 cases (80%) and basophilia greater than 2% was noted in 3 cases (60%). Cytogenetic study showed the presence of a t (9.22) in all cases, which was isolated in 1 case. The BCR-ABL transcript was of the p190 type in 2 cases and p210 in 2 cases, while the molecular study was not done in the remaining case. Four patients were treated with tyrosine kinase inhibitor (TKI) alone with the achievement of complete remission (CR) in 3/4 of the cases while one patient was treated with the combination TKI and chemotherapy with good evolution. Allograft was not done for all patients, in 2 cases for the absence of an HLA compatible siblings donor. The median follows up was 108 months. Relapse was observed in 2 patients with CR2 in both cases. The five years OS was 80%. Summary/Conclusion: Phi+ AML in our series is higher than that reported in the literature (1.8 vs <1%) this could be explained by the underestimation of the total number of AML in our country because some patients with AML (>55 years old) are not treated. The major question that arises in front of each phi+ AML is: is it a newly phi+ AML or a CML diagnosed at a blast phase? Previous abnormalities of the blood count, significant myelemia, blood basophilia >2% and the presence of associated cytogenetic abnormality tends towards CML diagnosed at a blast phase while the BCR-ABL transcript type is non-specific. By referring to these data, we can deduce that for our series most probably it is a newly phi+ AML in 2 cases. The major problem posed in the different series is the absence of standardized treatment due to the rarity of the pathology.

High plasma IL-6 levels following haploidentical allogeneic hematopoietic stem cell transplantation post-transplant cyclophosphamide as predictor of early death and worse outcome

IntroductionHaploidentical hematopoietic stem cell transplantation (haplo-HSCT) can be used as an alternative procedure in the absence of HLA-compatible donors. The use of high doses of cyclophosphamide after infusion improves the prognosis and eliminates the need for T cell depletion in vivo. Among the main complications of haplo-HSCT are acute graft-versus-host disease (a-GVHD) and cytokine release syndrome (CRS). This is a systemic inflammatory response that leads to the release of inflammatory proteins, including IL-6. This syndrome has several clinical features, with mild to severe symptoms. This study aimed to compare plasma IL-6 levels in patients submitted to different HSCT types and to associate them with the presence of acute graft versus host disease (a-GVHD), CRS and survival. MethodsA total of 84 patients (22 haploidentical and 62 non-haploidentical) were evaluated at different times. The IL-6 levels in haplo and non-haplo-HSCT recipients were measured before transplantation and on days D7, D14, D28, D60, and D100. ResultsIL-6 levels were higher in haplo-HSCT recipients than in non-haplo-HSCT recipients, remaining elevated from D14 until D100 (P = 0.006) and a cut-off ≥11 pg/mL on D7, which is related to worse overall survival. In our study, we found no association with a-GVHD (P = 0.239), a common complication of this type of transplant, but we found a relationship between the increase in IL-6 and CRS (P = 0.021). ConclusionIL6 can be used as a biomarker for patients submitted to haplo-HSCT, allowing clinical interference in patients having levels of IL-6 times larger than normality values, avoiding early death in this group of patients.

Immediate Allogeneic Hematopietic Stem Cell Transplantation for Patients with NPM1-Mutated AML in Molecular Relapse

BackgroundAccording to ELN 2017 classification NPM1-mutated AML is characterized as favorable or intermediate risk depending on the coexistence of FLT3 mutations. For pts with favorable risk profile allogeneic hematopoietic stem cell transplantation (HSCT) in first complete remission (CR) is not recommended. Because NPM1 mutations are stable, and persisting or increasing levels are a strong predictor of relapse, regular monitoring of measurable residual disease (MRD) by quantitative PCR (qPCR) is recommended. Early HSCT in molecular relapse can be an effective treatment strategy and avoid possible complications of reinduction chemotherapy. From 2014 we started to search for a donor immediately after molecular relapse and proceed to HSCT without reinduction chemotherapy.MethodsMRD was monitored at least every 3 months (mos) in all pts with NPM1-mutated AML in CR by qPCR in bone marrow or peripheral blood. Molecular relapse was defined as an increase of MRD above a cut-off of 1% NPM1/ABL1. The conditioning regimen consisted of Treosulfan (Treo, 30g/m 2) and Fludarabin (Flu, 120mg/m 2). In pts with hematological relapse or a very high NPM1 ratio at the time of HSCT Melphalan (Mel, 100mg/m 2) was added before Treo/Flu to induce aplasia. Donors were HLA-compatible unrelated donors in 10/13 pts, HLA identical sibling in 1 pt and haploidentical related donors in 2 pts. All pts were transplanted with G-CSF stimulated peripheral blood stem cells. Immunosuppression consisted of ATG and Ciclosporin in combination with MTX or MMF and posttransplant Cyclophosphamide for haploidentical HSCT (2 pts).Results17/37 pts fit for allogeneic transplantation relapsed after initial induction and consolidation therapy. 4 pts showed a hematological relapse. In 13/15 pts (median age 52 (37-72) years) a molecular relapse was detected at a median of 9 (6-42) mos after diagnosis, these pts are analyzed here. 10/13 relapses occurred within 12 mos after CR. 11/13 pts relapsed after achieving MRD negative remission, 2 pts progressed from MRD positive hematological remission. Median time from increase in MRD to HSCT was 2 (2-4) mos. Even after this short time period, 6/13 pts developed a hematological relapse before start of conditioning therapy. Together with 3 pts with a high molekular NPM1 level, these 6 pts received melphalan for induction of aplasia before starting Treo/Flu. Although hematological regeneration took longer for these pts compared to pts without melphalan, there were not more infectious or bleeding complications. All 13 pts reached complete hematological and molecular remission after HSCT. After a median follow-up of 20 (4-47) mos all pts are in CR. 2 pt relapsed 6 and 13 mos after HSCT, but reached CR again after DLI (1 pt.) and venetoclax(1pt). In all pts the duration of second CR after HSCT lasted longer than the first CR.ConclusionThis analysis shows the efficacy and feasibility of early allogeneic HSCT without reinduction chemotherapy in molecular or early hematological relapse for NPM1- mutated AML pts. For this strategy pts have to be monitored strictly at regular intervals after end of chemotherapy consolidation, because most relapses can be detected at molecular level. DisclosuresNo relevant conflicts of interest to declare.

Rapid and Safe T Cell Immune Reconstitution By T Cell Progenitor Injection Following Haploidentical Transplantation for Severe Combined Immunodeficiency (SCID)

Severe Combined Immunodeficiencies (SCID) are defined by a complete absence of T lymphocytes in the blood and lymphoid organs, with variable defects in other WBC subsets depending on the gene defect. From a clinical perspective SCIDs are characterized by early development of life-threatening infections accounting for early death if untreated. The treatment of choice is allogeneic HSCT with very high success rates if a HLA identical sibling (MRD) or unrelated donor (MUD) is used. However, due to the scarcity of matched-related donors, SCID can benefit from haploidentical HSCT. In contrast to the continuous improvement of HLA compatible donor transplantations, no significant improvements have been obtained over the last twenty years for haploidentical HSCT. The profound immunodeficiency during the first months following haploidentical HSCT exposes patients to opportunistic viral, bacterial and fungal infections, which account for approximately 30-40% of the transplant related mortality (TRM). The rapid restoration of the T-cell compartment is the main aim of stem cell therapy in this setting. To this end we have recently set up a phase I/II clinical trial (ClinicalTrials.gov Identifier: NCT03879876) aiming to accelerate the immune reconstitution by injection of ex vivo generated Human T lymphoid progenitors (ProTcell TM) following haploidentical HSCT. T cell progenitors in this trial are generated in vitro within 7 days from mobilized peripheral blood (mPB) CD34 + hematopoietic stem and precursor cells (HSPCs) using our Notch ligand Delta-like 4 GMP culture platform so called SMART Immune's SMART101 product.This open-label, non-randomized study evaluates safety and efficacy of the SMART101 injection following CD34 + selected, haploidentical HSCT in SCID patients and is designed as a dose-escalation study comprising 6 doses of the SMART101 product obtained from the patient's haploidentical stem cell graft. The aim of this protocol is to define the highest efficacy dose without any toxicity.The conditioning regimen is based on Busulfan and Fludarabine according to IE-WP/EBMT guidelines with upfront administration of ATG to prevent graft rejection. Tight monitoring of ATG serum levels is applied in order to assure injection of SMART101 when ATG is below the lymphotoxicity threshold.Here we report the results of the first two SCID patients. P1 presented a homozygous Artemis deficiency. At diagnosis he had an ALC of 341/µl, with complete absence of T cells (CD3 + < 4/µl, CD4 + < 1/µl, CD8 + < 2/µl) and B cells (CD19 + 0/µl). NK cells were present in the normal range for age (CD16 +CD56 + 331/µl).In the absence of an HLA compatible donor, the patient's father was chosen as haploidentical stem cell donor.P1 received upfront ATG (5 mg /kg total dose), Busulfan (AUC of 16058 microM.min) and Fludarabine (160 mg/m²). He received Defibrotide prophylaxis from D0 until D+21, as well as Ursodeoxycholic acid until D+80. The CD34 + immunoselected graft contained 1.04 x 10 8 nucleated cells/kg with 24.15 x10 6 CD34 + cells/kg and 4000 CD3 + cells/kg on D0. After ATG monitoring 0.12x10 6 Smart101 cells were administered at D+14 post- HSCT.In the follow-up P1 didn't develop any acute or chronic SAEs, no acute or chronic GVHD, and no infection. He was discharged at D+121 post HSCT.The day +100 post transplantation CD4 + cell count/microliter exceeded 10 times the CD4 + count of our historical cohort of RAG1/2 or Artemis deficient patients transplanted with haploidentical HSCT alone following the same conditioning regimen.At 6 months post HSCT this difference remains important (851 versus 300 CD4 + cells/µl); Ig replacement therapy could be stopped as early as 9 months post transplantation and vaccinations have been started. At last follow up; almost 14 months post HSCT P1 is alive and well.P2 had an undefined molecular SCID diagnosis. She has been treated with the same conditioning regimen and received the second dose of 0.2x10 6 CD7 + cells, but unfortunately died from severe VOD emphasizing the need to replace chemotherapy with less toxic myeloablative agents.The preliminary results obtained after injection of Human T lymphoid progenitors in P1 are encouraging. While deserving confirmation in larger numbers of patients they could represent an important step forward in improving the outcome of haploidentical HSCT for SCID. DisclosuresCavazzana: Smart Immune: Other: co-founder.

Significance of Degree of HLA Disparity When Using Haploidentical Donors with T-Replete PBSC and Post-Transplantation Cyclophosphamide (PTCy) in Acute Myeloid Leukemia (AML) in First Complete Hematologic Remission (CR1)

Background: Haploidentical allogeneic hematopoietic cell transplantation (haplo) has expanded applicability of the procedure to patients for whom a suitable HLA compatible donor was not available in the past. A small multicenter retrospective study of 185 patients with hematologic malignancies who received a nonmyeloablative preparative regimen followed by infusion of bone marrow (BM) hematopoietic cells from haploidentical donors showed no significant association between the number of HLA mismatches (HLA-A, -B, -C, and -DRB1 combined) and risk of acute grade 2-4 graft-versus-host disease (GVHD) (hazard ratio [HR]=0.89; P=0.68 for 3-4 mismatches vs fewer antigen mismatches). This haploidentical transplant platform has certainly evolved. Nowadays, G-CSF mobilized peripheral blood stem cells (PBSC) are commonly used owing to its increased convenience vis-à-vis performing a BM harvest.Study population: Here, we evaluate post transplant outcomes when using haploidentical donors with T-replete PBSC and PTCy in AML in CR1. A total of 494 patients (4/8 HLA mismatch (group 1)=360, 2-3/8 HLA mismatch (group 2)=134) underwent the procedure at an EBMT participating center. The primary endpoints were cumulative incidences of grade 2-4 acute GVHD and chronic (all grades) GVHD. Secondary endpoints included cumulative incidence of relapse (RI), non-relapse mortality (NRM), leukemia-free (LFS) and overall survival (OS) and GVHD-free relapse-free survival (GRFS).Results: Group 1 and group 2 were not statistically different in regards to median age at allografting (54.1 vs. 56.1 years, p=0.51), median year of haplo transplantation (2018 vs. 2018, p=0.36), incidence of de novo AML (86.4% vs. 88.1%, p=0.63), Karnofsky equal or more than 90 (77.5% vs. 79.1%, p=0.70), and use of myeloablative conditioning (MAC) (44.7% vs. 48.5%, p=0.45). Patients in group 1 had a longer time from diagnosis to haplo-transplantation (5.3 vs. 4.9 months, p=0.03). In multivariate analysis, group 1 and group 2 did not differ in cumulative incidence of grade 2-4 acute GVHD (Hazard ratio (HR)=0.89 (95%CI=0.62-1.26), p=0.51) but group 1 had a significantly higher incidence of chronic (all grades) GVHD (HR=1.49 (95%CI=1.02-2.16), p=0.04). There was no difference in RI (HR=0.73 (95%CI=0.47-1.14), p=0.17), NRM (HR=1.25 (95%CI=0.78-2.02), p=0.36), LFS (HR=0.95 (95%CI=0.69-1.31), p=0.76), OS (HR=1.09 (95%CI=0.76-1.55), p=0.64) and GRFS (HR=1.07 (95%CI=0.81-1.42), p=0.64) between the groups. Presence of adverse cytogenetics was independently associated with higher RI (HR=1.90 (95%CI=1.20-2.99), p=0.006), inferior LFS (HR=1.59 (95%CI=1.15-2.19), p=0.005), inferior OS (HR=1.48 (95%CI=1.05-2.08), p=0.03), and worse GRFS (HR=1.54 (95%CI=1.17-2.04), p=0.002).Conclusion: Results show that patients undergoing haplo-transplantation with 4/8 (vs. 2-3/8) HLA mismatches have a higher incidence of chronic GVHD (all grades) without adversely affecting acute grade 2-4 GVHD, RI, LFS, OS and GRFS. DisclosuresLabopin: Jazz Pharmaceuticals: Honoraria. Bazarbachi: Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Abbvie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Hikma: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Astra Zeneca: Membership on an entity's Board of Directors or advisory committees. Blaise: Jazz Pharmaceuticals: Honoraria. McDonald: BioCryst Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees. Forcade: Novartis: Other: travel grant. Ciceri: IRCCS Ospedale San Raffaele: Current Employment. Mohty: Takeda: Honoraria; Astellas: Honoraria; Adaptive Biotechnologies: Honoraria; Novartis: Honoraria; Celgene: Honoraria, Research Funding; Bristol Myers Squibb: Honoraria; Sanofi: Honoraria, Research Funding; Janssen: Honoraria, Research Funding; Gilead: Honoraria; Jazz: Honoraria, Research Funding; Pfizer: Honoraria; Amgen: Honoraria.

ТРАНСПЛАНТАЦИЯ ПУПОВИННОЙ КРОВИ У ДЕТЕЙ: ОБЗОР ЛИТЕРАТУРЫ И ОПЫТ ОДНОГО ЦЕНТРА

Umbilical cord blood (CB) has been used successfully as hematopoietic stem cells (HSCs) in adults and adults with malignant and non-malignant diseases in which there are indications for HSC transplantation (HSCT), and when an HLA-compatible related or unrelated donor is not available. CB, like any source of HSC, has certain advantages and disadvantages, which also determine the features of its use in transplantation. The article presents the experience of using CB as a source of HSC in pediatric patients at the Russian Children's Clinical Hospital (RCCH). Materials and methods of research: in a retrospective single-center continuous non-randomized uncontrolled open study includes 16 patients with various malignant diseases and 16 patients with non-malignant diseases, who underwent CB transplantation in the bone marrow transplantation department of the Russian Children's Clinical Hospital from 1997 to 2012. The peak of CB transplant activity occurred in the period from 2006 to 2010. The age of the patients at the time of the transplantation ranged from 6 months to 14 years. In 10 patients, a CB transplant from HLA-identical related donors was used, in 22 – from unrelated HLA-identical and HLA-incompatible for 2 or more antigens obtained from domestic CB banks. In addition to CB, six children were given bone marrow or peripheral blood stem cells from HLA-identical siblings as a transplant. The majority of patients (n=20) received one CB sample, 10 patients – 2 samples and two – 3. Results: implantation of the transplant was recorded in 27 children (84%), which 17 (53%) were alive, 10 (31%) died at different timesof post-transplant period. In 5 (16%) patients, implantation did not occur, of which one (3%) died, the cause of mortality in pediatric patients was a relapse of the underlying diseases. Acute graftversus-host reaction (GVHD) after CB transplantation was assessed in 27 (84%) patients of this study, among them 17 (63%) were diagnosed with acute GVHD stages I-II, 3 (11%) – stage III–IV (life-threatening form). Chronic GVHD was assessed in 18 (56%) patients included in the study, with 5 (28%) diagnosed with a limited form and 3 (17%) with an extensive form. Overall survival (OS) for the entire group of patients (n=32) was 58,3±8,8%, 5-year dormant survival rate (DSR) – 53±8.8%. OS in non-malignant diseases was higher (68%) than for malignant diseases (56%), but no statistically significant differences in OS were obtained in the two groups (p&gt;0,05), as well as when comparing OS and DSR when using one or several samples of CB. Conclusion: CB remains available and acceptable source of stem cells for HSCT. At our center, the survival rates of patients after CB transplantation are comparable to those of international registries. The improvement of the method and the results of haploidentical SCT in recent years has led to a decrease in interest and transplantation activity (including in our center) using CB as a source of HSC. However, the unexplored antileukemic potential of CB stem cells, as well as a number of potential resources for improving and optimizing the use of this HSC source, may increase the chances of future CB transplantation.

Prospective KIR genotype evaluation of hematopoietic cell donors is feasible with potential to benefit patients with AML

Donor KIR and recipient HLA combinations that minimize inhibition and favor activation of the NK repertoire are associated with improved outcomes after allogeneic hematopoietic cell transplantation (HCT) in patients with myeloid neoplasia. We prospectively evaluated a weighted donor ranking algorithm designed to prioritize HLA-compatible unrelated donors (URDs) with weak inhibitory KIR3DL1/HLA-Bw4 interaction, followed by donors with nontolerized activating KIR2DS1, and finally those with KIR centromeric B haplotype. During donor evaluation, we performed KIR genotyping and ranked 2079 URDs for 527 subjects with myelodysplastic syndrome (MDS) or acute myelogenous leukemia (AML). Among all patients, 394 (75%) had at least 1 KIR-advantageous donor, and 263 (50%) underwent HCT. In patients with AML, KIR3DL1 weak inhibition provided protection from relapse. Compared with KIR3DL1-Weak Inhibiting donors, KIR3DL1-Noninteracting donors were associated with increased risk of relapse (HR, 2.97; 95% CI, 1.33-6.64; P = .008) and inferior event-free survival (EFS; HR, 2.14; 95% CI, 1.16-3.95; P = .015). KIR3DL1-Strong Inhibiting donors were associated with HR, 1.65 (95% CI, 0.66-4.08; P = .25) for AML relapse and HR, 1.6 (95% CI, 0.81-3.17; P = .1) for EFS when compared with the use of KIR3DL1-weak inhibiting donors. Donor KIR2DS1/HLA-C1 status and centromeric KIR haplotype-B content were not associated with decreased risk of AML relapse. There was no benefit to KIR-based donor selection in patients with MDS. This study demonstrates that donor KIR typing is feasible, and prioritization of donors with certain KIR3DL1 genotypes may confer a protection from relapse after HCT in patients with AML.

Pretransplant Calculated Panel Reactive Antibody in the Absence of Donor-Specific Antibody and Kidney Allograft Survival.

Panel reactive antibody informs the likelihood of finding an HLA-compatible donor for transplant candidates, but has historically been associated with acute rejection and allograft survival because testing methods could not exclude the presence of concomitant donor-specific antibodies. Despite new methods to exclude donor-specific antibodies, panel reactive antibody continues to be used to determine the choice of induction and maintenance immunosuppression. The study objective was to determine the clinical relevance of panel reactive antibody in the absence of donor-specific antibodies. Retrospective observational study of kidney allograft survival among 4058 zero HLA-A-, B-, DR-, and DQB1-mismatched transplant recipients without antibodies to donor kidney antigens encoded by these HLA gene loci. Among 4058 first and repeat transplant recipients, patients with calculated panel reactive antibody (cPRA) 1%-97% were not at higher risk of transplant failure, compared with patients with cPRA of 0% (death censored graft loss: hazard ratio, 1.07; 95% confidence interval, 0.82 to 1.41). Patients with cPRA ≥98% had a higher risk of graft loss from any cause including death (hazard ratio, 1.39; 95% confidence interval, 1.08 to 1.79) and death censored allograft failure (hazard ratio, 1.78; 95% confidence interval, 1.27 to 2.49). In stratified analyses, the higher risk of graft loss among patients with cPRA ≥98% was only observed among repeat, but not first, transplant recipients. In subgroup analysis, there was no association between cPRA and graft loss among living related transplant recipients. Calculated panel reactive antibody is poorly associated with post-transplant immune reactivity to the allograft in the absence of donor-specific antibody. This article contains a podcast at https://www.asn-online.org/media/podcast/CJASN/2021_01_25_CJN13640820_final.mp3.

Pre-emptive immunosuppression using tacrolimus monotherapy does not reduce the rate of early acute rejection in renal transplantation from live donors: a comparative cohort study.

The planned nature of live donor kidney transplantation allows for immunosuppression to be initiated in the pretransplant period. The aim of this study was to determine the effect of pre-emptive immunosuppression on acute rejection rates after live donor kidney transplantation. In two consecutive cohorts of live donor kidneys transplants, 99 patients received pre-emptive immunosuppression with tacrolimus monotherapy for 2weeks prior to transplantation (PET group - first era) and 100 patients received tacrolimus-based immunosuppression commencing on the day of transplantation (control group - second era). The main outcome measure was the incidence of biopsy-proven acute rejection (BPAR) in the first 3months post-transplantation. Tacrolimus levels were significantly higher in the PET group at day 4 post-transplant (PET 9.08±4.57 vs. control 5.92±3.64ng/ml; P<0.0001), but there were no significant differences in tacrolimus levels at day 7 (PET 8.22±3.58 vs. control 7.63±3.56ng/ml; P=0.2452). BPAR was numerically higher in the PET group, but this difference did not reach statistical significance (PET 13/99 vs. control 6/100; P=0.097). There were no differences in allograft function measured by serum creatinine at 1year (PET 130±36 vs. control 142±69μmol/l; P=0.6829). Graft survival at 1year was equivalent in both groups (PET 96.9 vs. control 97.0%; P=0.9915). This study suggests that there is little role for the use of pre-emptive tacrolimus monotherapy in ABO blood group and HLA-compatible live donor kidney transplantation in patients on triple maintenance immunosuppression.