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Human leukocyte antigen (HLA) genes are extraordinary for their extreme diversity and widespread impact on human health and disease. More than 30,000 HLA alleles have been officially named and more alleles continue to be discovered at a rapid pace. HLA typing systems which have been developed to detect HLA diversity have advanced rapidly and are revolutionizing our understanding of HLA's clinical importance. However, continuous improvements in knowledge and technology have created challenges for clinicians and scientists. This review explains how differences in HLA typing systems can impact the HLA types that are assigned. The consequences of differences in laboratory testing methods and reference databases are described. The challenges of using HLA types that are not equivalent are illustrated. A fundamental understanding of the continual expansion of our understanding of HLA diversity and limitations in some of the typing data is essential for using typing data appropriately in clinical and research settings. [ABSTRACT FROM AUTHOR]

In 2009 calculated panel reactive antibody (CPRA) replaced PRA as the metric for HLA sensitization in the US kidney allocation system. During the next four years, registrants with at least one unacceptable antigen increased (34–40%) and registrants with ≥98% PRA/CPRA increased from 7% to 9% of the waitlist. These changes were accompanied by a reduction in kidney offers refused for positive crossmatch: 14,137 (1.7%) in 2009 and 3,310 in 2013 (0.4%). Registrants with ≥98% PRA/CPRA had highest rates of refusal but also showed substantial improvement (20% in 2009 vs 8% in 2013). For registrants with ≥98% PRA/CPRA, 45% of accepted offers in 2009 were not transplanted into the intended recipient compared to 11% in 2013. Transplant rates remained low for these patients (∼50/1000 active patient-years), but rates improved for patients with 80–97% PRA/CPRA (223/1000 active patient-years in 2009 vs 354/1000 in 2013). In 2013, 40% regraft candidates had CPRA ≥98% compared to 4% of primary graft candidates. More females than males were ≥98% CPRA (14% vs 7%) and more females had CPRA above 0 (50% vs 28%). In the CPRA era, listing of unacceptable antigens increased, positive crossmatches were diminished and transplant rates for sensitized patients improved. [ABSTRACT FROM AUTHOR]

Abstract: HLA disparity between hematopoietic stem cell donors and recipients is one of the most important factors influencing transplant outcomes, but there are no well-accepted guidelines to aid in selecting the optimal donor among several HLA mismatched donors. In this report, HLA-A is used as a model to illustrate factors that are barriers to delineating the relationship between specific HLA mismatches and transplant outcomes in the United States. Patients in this investigation received transplants for hematologic malignancies that were facilitated by the National Marrow Donor Program (NMDP) between 1990 and 2002 (n = 4226). High-resolution HLA typing was performed for HLA-A, -B, -C, -DRB1, -DQA1, -DQB1, -DPA1, and -DPB1. HLA-A mismatches were observed in 745 donor-recipient pairs and 62% of these pairs also had disparities at HLA-B, -C, and/or -DRB1. The HLA-A mismatches involved 190 different combinations of HLA-A alleles and 51% of these were observed in only 1 pair. Addition of a single HLA-A disparity when HLA-B, -C, and -DRB1 were matched (n = 282) was associated with increased mortality (odds ratio [OR] = 1.32, confidence interval [CI] 1.07-1.63). When HLA-B, -C, and -DRB1 were matched, the most frequent HLA-A mismatches were HLA-A∗0201:0205 (n = 28), HLA-A ∗0301:0302 (n = 15), HLA-A ∗0201:0206 (n = 15), HLA-A ∗0201:6801 (n = 12), HLA-A∗0101:1101 (n = 11), and HLA-A∗0101:0201 (n = 10). There were no statistically significant relationships between any of these disparities and transplant outcomes (engraftment, acute and chronic graft-versus-host disease [aGVHD, cGVHD] relapse, treatment-related mortality [TRM], or overall survival [OS]) when adjustments for multiple comparisons were considered. Achieving 80% power to detect an effect of any 1 of these 6 HLA-A disparities on survival is estimated to require a total transplant population of 11,000 to more than 1 million U.S. donor-recipient pairs depending upon the HLA disparity. Thus, alternative approaches are required to develop a clinically relevant ranking system for specific HLA disparities in the United States. [Copyright &y& Elsevier]

To the Editor: More than half of the non-Hodgkin lymphomas (NHL) occurring in children, adolescents, and young adults (CAYA) in North America and Europe are comprised mature B-cell NHL (B-NHL) [[1]]. Salvage reinduction regimens resulted in 6/12 (50%) patients achieving a CR, 5/12 (41.6%) patients attaining a PR and 1/12 (8.3%) patients with progressive disease (PD). Post MAC autoSCT 7/12 patients (58%) were in a CR, two patients (16.7%) were in a PR, two patients (16.7%) had stable disease and one patient (8.3%) had PD. Amongst the three patients with diffuse large B-cell lymphoma one was in CR, one had stable disease and one had PD post MAC autoSCT. [Extracted from the article]

HLA‐B*56:75 has a nonsynonymous C to G substitution in codon 73 compared to HLA‐B*56:01:01:02. [ABSTRACT FROM AUTHOR]

• The use of HLA-haploidentical and umbilical cord blood transplants expands the access to transplantation is regardless of patient race or ethnicity. • The risk of grade II-IV and III-IV acute graft-versus-host disease is increased after umbilical cord blood transplantation. • The risk of transplantation-related mortality is increased with umbilical cord blood transplantation. Although hematopoietic cell transplantation from an HLA-matched unrelated donor is potentially curative for hematologic malignancies, survival is lower for African Americans compared with Caucasians. Because only approximately 20% of African Americans will have an HLA-matched unrelated donor, many of these patients undergo HLA-haploidentical relative or umbilical cord blood transplantation. In this study, we analyzed outcomes after HLA-haploidentical related donor (n = 249) and umbilical cord blood (n = 118) transplantations in African American patients with hematologic malignancy between 2008 and 2016. The predominant disease was acute myelogenous leukemia for recipients of both types of donor grafts. The incidences of grade II-IV and III-IV acute graft-versus-host disease were higher after umbilical cord blood transplantation compared with HLA-haploidentical relative transplantation (56% and 29%, respectively, versus 33% and 11%, respectively; P <.0001). The 2-year incidence of transplantation-related mortality adjusted for age and conditioning regimen intensity was higher after umbilical cord blood transplantation compared with HLA-haploidentical related donor transplantation (31% versus 18%; P =.008); however, there were no between-group differences in the 2-year adjusted incidence of relapse (30% versus 34%; P =.51), overall survival (54% versus 57%; P =.66), or disease-free survival (43% versus 47%; P =.46). Our findings show that the use of HLA-haploidentical and umbilical cord blood transplants expands the access to transplantation with comparable leukemia-free and overall survival for African Americans with hematologic malignancies. [ABSTRACT FROM AUTHOR]

Allogeneic stem cell transplantation (AlloSCT) from an HLA-matched sibling donor is the only known curative therapy in high-risk SCD patients (Talano/Cairo, EJH , 2015). Unfortunately only about 15% of high-risk SCD patients have an HLA-matched unaffected sibling donor. T cell depletion has been employed to reduce AGVHD. We reported a very low incidence of GVHD in pediatric recipients receiving CD34 enriched HPC products with PBMNC addback from MUD donors (Geyer/Cairo et al, BJH, 2012). Rapid NK cell reconstitution after AlloSCT is associated with a significant improvement in 1yr OS (Pical-Izard, BBMT , 2015). Recently, we reported promising results for high-risk SCD patients at 1 yr follow-up after FHI CD34 enriched/PBMNC with addback with the probability of 1-yr OS 88.2% (Cairo, et al, JAMA Peds, 2019). To investigate donor chimerism, immune reconstitution and the incidence of GVHD in high-risk SCD patients following AlloSCT using FHI CD34 enrichment/PBMNC (2 × 105 CD3/kg) addback. CD34 cells were enriched using the CliniMACS® system, kindly provided by Miltenyi Biotec, with a target dose of 10 × 106 CD34+ cells/kg. PBMNC were added back to the final CD34 product at a dose of 2 × 10*5 CD3/kg. Whole blood and CD71-enriched erythroid lineage chimerism were determined by STR. Immune cell, subset reconstitution, NK function, CD107a and granzyme B were assessed by flow cytometry as previously described (Geyer/Cairo et al. BJH , 2012, Chu/Cairo et al, Can Imm Res , 2015). The cumulative incidence of grade II-IV and late AGVHD was 6.2 % and moderate and/or severe CGVHD incidence was 6.7%, respectively (Fig. 1A). There was 100% engraftment of neutrophils and platelets. The median day post-HISCT to neutrophil and platelet engraftment was +9 and +19, respectively. Whole blood donor chimerism (mean±SEM) at 1-yr, 2-ys, and 3-ys post-HISCT was 97±1%, 97±1%, 97±1%, respectively (Fig.1B). Donor chimerism for CD71-enriched erythroid lineage cells (mean±SEM) at 1-yr, 2-yrs, 3-yrs post-HISCT was 97±2%, 98±1%, 98±1%, respectively (Fig.1B). The time to recovery of minimal normal levels for CD3 (800 cells/ul), CD4 (400 cells/ul), CD8 (200 cells/ul), & CD19 cells (200 cells/ul), was approximately 365, 365, 270, and 60 days post-HISCT, respectively (Fig.1C). NK reconstitution was rapid and peaked at d+30 (36±9%) with higher level of activating receptors NKp46, NKG2D & KIR2DS and inhibitory receptors NKG2A, CD94 and KIR2DL2/3. NK cytotoxicity against K562 (E:T = 10:1) peaked at d+30 and d+180 vs pre-transplant (p<0.01) with enhanced CD107a (Fig. 1D). The PBMNC addback facilitated rapid donor chimerism & immune reconstitution with a low probability of Grade II-IV AGVHD. The rapid NK reconstitution may have in part contributed to the excellent 1yr OS in this study (FDA R01FD004090 (MSC)). This approach is comparable to the method of CD3 TCRa/b-CD19 depletion. [ABSTRACT FROM AUTHOR]

Myeloablative conditioning and allogeneic hematopoietic stem cell transplant (alloHSCT) in children with acute myeloid leukemia (AML) in first complete remission (CR1) may be associated with significant acute toxicity and late effects. Reduced-intensity conditioning (RIC) and alloHSCT in children is safe, feasible, and may be associated with less adverse effects. Gemtuzumab ozogamicin (GO) induces a response in 30% of patients with CD33 + relapsed/refractory AML. The dose of GO is significantly lower when combined with chemotherapy. We examined the feasibility and toxicity of RIC alloHSCT followed by GO targeted immunotherapy in children with CD33 + AML in CR1/CR2. Conditioning consisted of fludarabine 30 mg/m 2 × 6 days, busulfan 3.2 to 4 mg/kg × 2 days ± rabbit antithymocyte globulin 2 mg/kg × 4 days followed by alloHSCT from matched related/unrelated donors. GO was administered ≥60 days after alloHSCT in 2 doses (8 weeks apart), following a dose-escalation design (4.5, 6, 7.5, and 9 mg/m 2 ). Fourteen patients with average risk AML received RIC alloHSCT and post-GO consolidation: median age 13.5 years at transplant (range, 1 to 21), male-to-female 8:6, and disease status at alloHSCT 11 CR1 and 3 CR2. Eleven patients received alloHSCT from 5-6/6 HLA-matched family donors: 8 received peripheral blood stem cells, 2 received bone marrow, and 1 received related cord blood transplantation. Three patients received an unrelated allograft (two 4-5/6 and one 9/10) from unrelated cord blood unit and bone marrow, respectively. Neutrophil and platelet engraftment was observed in all assessable patients (100%), achieved at median 15.5 days (range, 7 to 31) and 21 days (range, 10 to 52), respectively. Three patients received GO at dose level 1 (4.5 mg/m 2 per dose), 5 at dose level 2 (6 mg/m 2 per dose), 3 at dose level 3 (7.5 mg/m 2 per dose), and 3 at dose level 4 (9 mg/m 2 per dose). Three of 14 patients received only 1 dose of GO after alloHSCT. One patient experienced grade III transaminitis, which resolved; no grade IV transaminitis, no grade III/IV hyperbilirubinemia, or sinusoidal obstructive syndrome were observed. The second dose of GO was given at median of 143 days (range, 120 to 209) after alloHSCT. Probability of grades II to IV acute and chronic graft-versus-host disease were 21% and 33.5%, respectively. Probability of overall survival after RIC alloHSCT and GO consolidation at 1 and 5 years was 78% and 61%, respectively. Probability of 5-year event-free survival after RIC alloHSCT and GO consolidation in patients in CR1 was 78%. No dose-limiting toxicities probably or directly related to GO were observed in this cohort. This preliminary data demonstrate that RIC followed by alloHSCT and consolidation with GO appears to be safe in children and adolescents with CD33 + AML in CR1/CR2. A phase II trial is currently underway investigating this approach with a GO dose of 9 mg/m 2 per dose. [ABSTRACT FROM AUTHOR]

In subjects mismatched in the HLA alleles C*03:03/C*03:04 no allogeneic cytotoxic T-lymphocyte responses are detected in vitro. Hematopoietic stem cell transplantation (HSCT) with unrelated donors (UDs) showed no association between the HLA-C allele mismatches (CAMMs) and adverse outcomes; antigen mismatches at this and mismatches other HLA loci are deleterious. The absence of effect of the CAMM may have resulted from the predominance of the mismatch C*03:03/C*03:04. Patients with hematologic malignancies receiving UD HSCT matched in 8/8 and 7/8 HLA alleles were examined. Transplants mismatched in HLA-C antigens or mismatched in HLA-A, -B, or -DRB1 presented significant differences (P < .0001) in mortality (hazard ratio [HR] = 1.37, 1.30), disease-free survival (HR = 1.33, 1.27), treatment-related mortality (HR = 1.54, 1.54), and grade 3-4 acute graft-versus-host disease (HR = 1.49, 1.77) compared with the 8/8 group; transplants mismatched in other CAMMs had similar outcomes with HR ranging from 1.34 to 172 for these endpoints. The C*03:03/C*03:04 mismatched and the 8/8 matched groups had identical outcomes (HR ranging from 0.96-1.05). The previous finding that CAMMs do not associate with adverse outcomes is explained by the predominance (69%) of the mismatch C*03:03/03:04 in this group that is better tolerated than other HLA mismatches. [ABSTRACT FROM AUTHOR]

We studied the effect of allele-level matching at human leukocyte antigen (HLA)-A, -B, -C, and -DRB1 in 1568 single umbilical cord blood (UCB) transplantations for hematologic malignancy. The primary end point was nonrelapse mortality (NRM). Only 7% of units were allele matched at HLA-A, -B, -C, and -DRB1; 15% were mismatched at 1,26% at 2, 30% at 3, 16% at 4, and 5% at 5 alleles. In a subset, allele-level HLA match was assigned using imputation; concordance between HLA-match assignment and outcome correlation was confirmed between the actual and imputed HLA-match groups. Compared with HLA-matched units, neutrophil recovery was lower with mismatches at 3,4, or 5, but not 1 or 2 alleles. NRM was higher with units mismatched at 1,2,3,4, or 5 alleles compared with HLA- matched units. The observed effects are independent of cell dose and patient age. These data support allele-level HLA matching in the selection of single UCB units. [ABSTRACT FROM AUTHOR]

HLA disparity has a negative impact on the outcomes of hematopoietic cell transplantation (HCT). We studied the independent impact of amino acid substitution (AAS) at peptide-binding positions 9, 99, 116, and 156, and killer immunoglobulin-like receptor binding position 77 of HLA-A, B, or C, on the risks for grade 3-4 acute graft-versus-host disease (GVHD), chronic GVHD, treatment-related mortality (TRM), relapse, and overall survival. In multivariate analysis, a mismatch at HLA-C position 116 was associated with increased risk for severe acute GVHD (hazard ratio [HR] = 1.45,95% confidence interval [CI] = 1.15-1.82, P = .0016). Mismatch at HLA-C position 99 was associated with increased transplant-related mortality (HR = 1.37,95% CI = 1.1-1.69, P = .0038). Mismatch at HLA-B position 9 was associated with increased chronic GVHD (HR = 2.28,95% CI = 1.36-3.82, P = .0018). No AAS were significantly associated with outcome at HLA-A. Specific AAS pair combinations with a frequency >30 were tested for association with HCT outcomes. Cysteine to tyrosine substitution at position 99 of HLA-C was associated with increased TRM (HR = 1.78, 95% = C11.27-2.51, P = .0009). These results demonstrate that donor-recipient mismatch for certain peptide-binding residues of the HLA class I molecule is associated with increased risk for acute and chronic GVHD and death. [ABSTRACT FROM AUTHOR]

Aim: 16% of adult kidney alone registrations in the US are broadly sensitized (80%+ CPRA). But some programs have a much lower percentage of such registrations. The aim of this study was to compare positive crossmatch rates and allocation in programs grouped according to their percentage of broadly sensitized patients. Methods: Data for adult kidney alone registrations were compared for three groups of large transplant programs (100+ candidates). Group 1 included programs with <5% of broadly sensitized candidates, group 2 programs with 5-<10% and group 3 programs with 10-20%. Results are based on the Organ Procurement and Transplantation Network (OPTN) database. Results: On 12/31/11, groups 1 and 2 had similar percentages of retransplant and female registrations (12% vs. 12%, 35% vs. 37%) and group 3 had higher percentages (15% for retransplant and 41% for females). In 2011, transplant rates were not significantly different between three groups. Group 1 had a significantly higher percentage of offers refused due to a positive crossmatch compared to groups 2 and 3 (1.5% vs. 0.3% and 0.4% for all offers, and 21% vs. 5% and 8% for offers to 80%+ CPRA patients). Group 1 also had a significantly higher percentage of offers accepted for transplant but kidneys not transplanted into the intended recipient (43% of all accepted offers vs. 21% and 5% for all offers, and 81% vs. 31% and 9% for offers accepted for 80%+ CPRA patients). In 2011, group 1 refused 191 offers due to a positive crossmatch and in 137 cases, an offer was accepted but the kidney was not ultimately transplanted into the intended recipient. Conclusions: The data seem to suggest that centers with a very low percentage of broadly sensitized candidates (group 1) may not be listing a realistic number of unacceptable antigens for their patients. High rates of refusals due to a positive crossmatch and offers accepted but kidneys not transplanted into the intended recipient can have a negative impact on the efficiency of kidney allocation. [Copyright &y& Elsevier]

Aim: Virtual cross matches (VXMs) are key to the success of KPD by aiding identification of compatible donors for sensitized candidates. We evaluated the success of unstandardized VXMs combined with donor preselection by National Kidney Registry (NKR) centers in a population of mostly sensitized and/or ABO incompatible patients. Methods: The NKR initiated 437 match offers among 62 US transplant centers based on acceptable VXMs between 3/14/2011 to 3/31/2012. We evaluated the accuracy of the VXM by examining whether or not offers were declined due to positive final XMs. The VXM considered antibodies to HLA-A, B, C, DRB1/3/4/5, DQB1 and DPB1 detected by Single Antigen assays and donor HLA typing. Each center established its own immunological criteria for donor acceptability. To reduce late stage match failures online pre-selection of donors was introduced in July 2011 which allowed centers to accept potential donors based on HLA types and other characteristics prior to a match run. Results: NKR centers achieved a 92% VXM accuracy rate and completed 181 transplants; 32% of these had PRA>80%. Only 29 (8%) offers were rejected by the recipients’ center due to an unacceptable positive final crossmatch. In most cases, the discrepancy with the VXM was due to DSA at or near the center’s threshold or to multiple DSAs when each fell below the threshold of unacceptability. Other cases were due to DQA antibodies (3), non-HLA antibodies (3), a change in antibody profile (1), and data entry error (1). Interestingly, the rate of false negative VXM remained unchanged after the implementation of the pre-selection strategy, while the rate of late-stage cancellations due to unacceptable donors decreased from 5% to 2%. Conclusions: Access to transplant for sensitized patients with minimal disruption of chains has improved by pre-selection of acceptable pairs, optimizing data entry for the VXM, frequent antibody monitoring following sensitizing events and good communication between transplant centers and their labs. Sinacore: NKR: Employee. [Copyright &y& Elsevier]

Aim: HLA compatibility is assessed by crossmatching (XM) and donor specific antibody (DSA) testing. Flow cytometric XM (FXM) results vary among centers due to variation in reagents and sample preparation. We evaluated FXM variability and effects of test standardization in 6 US centers participating in the HALT study. Methods: 6 labs performed FXM using 3 exchanges (Exch) including sera with weak DSA and either frozen (1) or fresh (2) cells. All samples were sent from 1 lab, which screened sera by single antigen beads and typed cells for HLA-A,B,C,DRB1/3/4/5,DQB1. HLA typing and DSA results were not revealed to the other labs until study completion. FXM data assessed included cell viability, pronase and anti-hIgG concentrations, instrument and channel settings, and fluorescence (FL) values. Four different cytometer types were used by the labs. Labs used their own methods for Exch 1 and 2. In Exch 3, sample preparation and reagents were standardized: pronase (2mg/ml); anti-hIgG dilution (1:500). Results: Each Exch had 10-24 T/B FXM comparisons. Exch 2 (S1 vs C1) was a negative control. shows range of variation in FL values. shows expected vs observed interpretations. Conclusions: The discrepant results produced by varying FXM methods raise concerns about the assessment of HLA compatibility results from multicenter clinical trials. Standardization of reagents and sample preparation improved FXM result concordance among centers demonstrating that standardization can reduce the variation of results often seen in a multicenter clinical trial. Partially funded by the NIH, NHLBI grant R34 HL10541. [Copyright &y& Elsevier]

A single mismatch in highly expressed HLA-A, -B, -C, and -DRB1 loci (HEL) is associated with worse outcomes in hematopoietic stem cell transplantation, while less is known about the cumulative impact of mismatches in the lesser expressed HLA loci DRB3/4/5, DQ, and DP (LEL). We studied whether accumulation of LEL mismatches is associated with deleterious effects in 3853 unrelated donor transplants stratified according to number of matches in the HEL. In the 8/8 matched HEL group, LEL mismatches were not associated with any adverse outcome. Mismatches at HLA-DRB1 were associated with occurrence of multiple LEL mismatches. In the 7/8 HEL group, patients with 3 or more LEL mismatches scored in the graft-versus-host vector had a significantly higher risk of mortality (1.45 and 1.43) and transplant-related mortality (1.68 and 1.54) than the subgroups with 0 or 1 LEL mismatches. No single LEL locus had a more pronounced effect on clinical outcome. Three or more LEL mismatches are associated with lower survival after 7/8 HEL matched transplantation. Prospective evaluation of matching for HLA-DRB3/4/5, -DQ, and -DP loci is warranted to reduce posttransplant risks in donor-recipient pairs matched for 7/8 HEL. [ABSTRACT FROM AUTHOR]

Abstract: Allogeneic hematopoietic stem cell transplantation (allo-HSCT) with myeloablative conditioning is associated with a 10%-40% risk of day +100 transplantation-related mortality (TRM). We evaluated the feasibility and safety of reduced-toxicity conditioning and allo-HSCT in 100 consecutive children and adolescent recipients (mean age, 9.2 ± 6.8 years). The mean duration of follow-up was 1278 ± 1042 days. Fifty patients had malignant disease. The median time to neutrophil recovery was 18 days, and the median time to platelet recovery was 43 days. Median donor chimerism in engrafted patients was 98% on day +100 and 98% on day +365. The cumulative incidence of acute graft-versus-host disease (GVHD) was 20% (95% confidence interval [CI], 12.1%-27.9%), and that of chronic GVHD was 13.5% (95% CI, 6.6%-20.4%). TRM was 3% (95% CI, 0%-6.4%) by day +100 and 13.6% (95% CI, 6.7%-20.5%) for the entire study period. The incidence of primary graft failure (PGF) was 16% overall, 31.4% after umbilical cord blood transplantation (UCBT), and 0% after allo-HSCT with matched unrelated or matched sibling donors (P < .0001). The incidence of PGF in UCBT recipients was 46.7% (14 of 30) in chemotherapy-naive recipients, versus 9.5% (2 of 21) in non–chemotherapy-naive recipients (P = .019). Five-year event-free survival was 59.5% ± 5%, and 5-year overall survival was 72.9% ± 5%. Only PGF and poor-risk disease status were significantly associated with decreased overall survival (P = .03). Reduced-toxicity conditioning allo-HSCT in pediatric recipients is associated with low TRM; however, chemotherapy-naive UCBT recipients have a significantly higher incidence of PGF. [Copyright &y& Elsevier]

Transplantation-related mortality (TRM) is high after HLA-mismatched umbilical cord blood (UCB) transplantation (UCBT). In utero, exposure to noninherited maternal antigen (NIMA) is recognized by the fetus, which induces T regulator cells to that haplotype. It is plausible that UCBTs in which recipients are matched to donor NIMAs may alleviate some of the excess mortality associated with this treatment. To explore this concept, we used marginal matched-pair Cox regression analysis to compare outcomes in 48 NIMA-matched UCBTs (ie, the NIMA of the donor UCB unit matched to the patient) and in 116 non–NIMA-matched UCBTs. All patients had a hematologic malignancy and received a single UCB unit. Cases and controls were matched on age, disease, disease status, transplantation-conditioning regimen, HLA match, and infused cell dose. TRM was lower after NIMA-matched UCBTs compared with NIMA-mismatched UCBTs (relative risk, 0.48; P = .05; 18% versus 32% at 5 years posttransplantation). Consequently, overall survival was higher after NIMA-matched UCBT. The 5-year probability of overall survival was 55% after NIMA-matched UCBTs versus 38% after NIMA-mismatched UCBTs (P = .04). When faced with the choice of multiple HLA-mismatched UCB units containing adequate cell doses, selecting an NIMA-matched UCB unit may improve survival after mismatched UCBT. [Copyright &y& Elsevier]

For children receiving allogeneic hematopoietic stem cell transplants (HSCTs), the toxicity of the conditioning regimen and graft failure remain challenges. We previously reported that targeted i.v. busulfan, fludarabine, and rabbit anti-thymocyte globulin (rATG) decreased toxicity but had a graft failure rate of 21%. To improve the engraftment rate, we replaced ATG with alemtuzumab, a monoclonal Ab targeting CD52. Thirty-five children with malignant and nonmalignant diseases were enrolled in this phase II prospective study. Twelve children had HLA-matched related donors (MRDs), 16 had 10 of 10, and 7 had 9 of 10 HLA allele-matched unrelated donors (MUDs). Thirty-one of 34 evaluable patients (91%) achieved a durable engraftment. All 3 patients who rejected had a nonmalignant disease and received a MUD transplantation (2 mismatched at 1 antigen). Three patients died of a transplantation-related complication (9% ± 5.2%). Seven patients had disease relapse or progression, 2 of whom died. At a median follow-up of 35 months (range, 15-85 months), the event-free survival (EFS) was 61% ± 9.0% and the overall survival (OS) was 78% ± 7.5%. The median time to neutrophil recovery, B cell, and T cell reconstitution were 16 days, 3 months, and 6 months, respectively. At 1 year, the median donor chimerism in whole blood, CD3, CD14/15, and CD19 subsets were 97%, 87%, 100%, and 99%, respectively. Six patients (17% ± 6.6%) developed acute graft-versus-host disease (aGVHD), only 2 of which were >grade II. Two patients (8% ± 5.4%) progressed to chronic GVHD (cGVHD). These results suggest that replacement of rATG with alemtuzumab may improve engraftment as well as decrease cGVHD rates without resulting in delays in immune reconstitution. [ABSTRACT FROM AUTHOR]

Currently, there is no well-accepted rating system for reliably predicting which HLA-mismatched (MM) unrelated donor should be selected for a patient without an HLA allele-matched donor. We evaluated the ability of an MM ranking system, HistoCheck, to predict the risk associated with HLA class I disparity in a population of 744 single allele or antigen HLA-A, -B, or -C MM myeloablative unrelated donor hematopoietic stem cell transplantation recipients with acute myelogenous leukemia, acute lymphoblastic leukemia, chronic myelogenous leukemia, or myelodysplastic syndrome, facilitated through the National Marrow Donor Program between 1988 and 2003. Multivariate models were used to adjust for other significant clinical risk factors. HLA MMs were scored using the HistoCheck Web-based tool, and the patients were divided into 4 quartiles: dissimilarity score (DSS) 1.04-2.84 (allele MM), DSS >2.84-13.75 (allele and antigen MM), DSS >13.75-19.39 (antigen MM), and DSS >19.39-36.62 (antigen MM). Using the lowest scoring quartile as the reference, the DSS groups were evaluated for associations with relapse, treatment-related mortality, acute and chronic graft-versus-host disease, leukemia-free survival, and overall survival in the entire cohort and also in subset analyses by disease and disease stage. No significant associations were found between DSS and any outcomes in the overall cohort using the quartile categories or treating DSS as a continuous variable. Higher DSS scores were associated with decreased engraftment in early-stage disease (P = .0003), but not in other disease stages. In summary, DSS does not correlate with transplantation outcomes, and the HistoCheck scoring system does not provide an effective technique for ranking HLA class I MM. The dataset used in this study is available to evaluate new algorithms proposed for donor selection. [Copyright &y& Elsevier]

Summary CD34-selected haploidentical and unrelated donor allogeneic stem cell transplantation (Allo SCT) in paediatric recipients is associated with sustained engraftment and low risk of acute graft- versus-host disease (a GVHD), but limited by delayed immune reconstitution and increased risk of viral and fungal infection. The optimal dose of donor T cells to prevent graft failure and minimize risk of early opportunistic infection and post-transplant lymphoproliferative disorder ( PTLD), while avoiding severe a GVHD, remains unknown. We prospectively studied CD34-selected 8-10/10 human leucocyte antigen ( HLA)-matched unrelated donor ( MUD) peripheral blood stem cell transplantation ( PBSCT) in a cohort of 19 paediatric Allo SCT recipients with malignant ( n = 13) or non-malignant ( n = 6) diseases. T cells were added back to achieve total dose 1·0-2·5 × 105 CD3+/kg. GVHD pharmacoprophylaxis consisted only of tacrolimus. All patients engrafted neutrophils. Probabilities of grade II- IV a GVHD, limited chronic GVHD (c GVHD), and extensive c GVHD were 15·8%, 23·3%, and 0%, respectively. One patient developed PTLD. One-year infection-related mortality was 5·6%. T cell immune reconstitution was delayed. One-year overall survival was 82·3%. Five patients with malignant disease ultimately died from progressive disease. CD34-selected MUD PBSCT using a defined dose of T cell add-back resulted in high rates of engraftment and low risk of grade II- IV a GVHD, early transplantation-related mortality, and extensive c GVHD. [ABSTRACT FROM AUTHOR]

Children with high-risk acute myelogenous leukemia (AML) (induction failure [IF], refractory relapse [RR], third complete remission [CR3]) have dismal outcomes. Over 80% of AML patients express CD33, a target of gemtuzumab ozogamicin (GO). GO is an active drug in childhood AML but has not been studied in a myeloablative conditioning regimen. We sought to determine the safety of GO in combination with busulfan/cyclophosphamide (Bu/Cy) conditioning before allogeneic hematopoietic stem cell transplantation (alloSCT). GO was administered on day −14 at doses of 3.0, 4.5, 6.0, and 7.5 mg/m2, busulfan on days −7, −6, −5, −4 (12.8-16.0 mg/kg), and cyclophosphamide on days −3 and −2 (60 mg/kg/day). GVHD prophylaxis consisted of tacrolimus and mycophenolate mofetil. We enrolled 12 patients: 8 IF, 3 RR, 1 CR3; median age: 3 years (1-17); median follow-up: 1379 days (939-2305). Nine received umbilical cord blood (UCB), 2 matched unrelated donors (MUDs) and 1 HLA-matched sibling donor: 3 patients each at GO doses of 3.0, 4.5, 6.0, or 7.5 mg/m2. No dose-limiting toxicities secondary to GO were observed. Day 100 treatment-related mortality (TRM) was 0%. Myeloid and platelet engraftment was observed in 92% and 75% of patients at median day 22 (12-40) and 42 (21-164), respectively. Median day +30 donor chimerism was 99% (85%-100%). The probability of grade II-IV acute graft-versus-host disease (aGVHD) was 42% and chronic GVHD (cGVHD) was 28%. One-year overall survival (OS) and event-free survival (EFS) was 50% (95% confidence interval [CI], 20.8-73.6). GO combined with Bu/Cy regimen followed by alloSCT is well tolerated in children with poor-risk AML. GO at 7.5 mg/m2 in combination with Bu/Cy is currently being tested in a phase II study. [ABSTRACT FROM AUTHOR]

We prospectively treated 80 patients with relapse of malignancy or secondary myelodysplasia after autologous hematopoietic cell transplantation (AHCT) with allogeneic HCT (allo-HCT) using a reduced-intensity conditioning regimen of fludarabine 150 mg/m2 plus intravenous busulfan 6.4 mg/kg. Both matched sibling (MSD) and unrelated donors (MUD) were allowed. Patients transplanted from MUD donors received more intensive graft-versus-host disease (GVHD) prophylaxis, including rabbit antithymocyte globulin (ATG) 10 mg/kg, mycophenolate mofetil, and an extended schedule of tacrolimus. With a median follow-up of 3.1 years (0.9-5.8), treatment-related mortality (TRM) at 6 months and 2 years was 8% and 23%, respectively. Neither TRM nor the rates of acute GVHD (aGVHD) were different in those with sibling or MUD donors. Donor CD3 cell chimerism >90% at day +30 was achieved more often in patients with MUD than with matched sibling donors, 70% versus 23% (P < .0001). Median event-free suvival was higher in patients who achieved early full donor chimerism (14.2 versus 8 months, P = .0395). Allo-HCT using this reduced-intensity conditioning regimen can be performed with low TRM in patients who have received a prior AHCT. Efforts to improve early donor CD3 chimerism may improve event-free survival. [ABSTRACT FROM AUTHOR]

G-CSF and GM-CSF both hasten myeloid engraftment post-MA-alloSCT; however, GM-CSF is earlier acting and less expensive. The objective was to evaluate efficacy/safety of sequential administration of GM-CSF followed by G-CSF in children post-MA-alloSCT. From January 2001 to June 2005, 31 children received 32 MA-alloSCT: mean age 6.65 yr; MRD BM or PBSC vs. related or unrelated UCB 11:21; malignant vs. non-malignant disorders 22:10. GM-CSF (250 μg/m2 IV QD) began on day of stem cell infusion. GM-CSF was switched to G-CSF (10 μg/kg IV QD) when WBC ≥ 300/mm3 × 2 days. G-CSF continued until ANC ≥ 2500/mm3 × 2 days, then tapered to maintain ANC ≥ 1000/mm3. Median time to myeloid engraftment (ANC ≥ 500/mm3 × 3 days) was 17 days [13 days vs. 24 days, MRD BM/PBSC vs. UCB (p < 0.0001)], occurring at a median time of two days after switch to G-CSF. Clinically relevant adverse events were bone pain (n = 8) and large pleural effusion (n = 1). It was estimated that sequential GM-CSF/G-CSF was cost-effective compared with G-CSF alone [cost-savings of $1311/patient ($41,952/study), 2007 Red Book™ Average Wholesale Price]. In summary, it was demonstrated that sequential administration of GM-CSF/G-CSF post-MA-alloSCT was safe, cost-effective and resulted in prompt myeloid engraftment. [ABSTRACT FROM AUTHOR]

Killer immunoglobulin-like receptor (KIR)-ligand mismatched natural killer (NK) cells play a key role in achieving durable remission after haplo-identical transplantation for acute myeloid leukaemia. We investigated the feasibility of transfusing haplo-identical, T-cell depleted, KIR-ligand mismatched NK cells, after conditioning therapy with melphalan and fludarabine, to patients with advanced multiple myeloma (MM) followed by delayed rescue with autologous stem cells. No graft-versus-host disease or failure of autologous stem cells to engraft was observed. There was significant variation in the number of allo-reactive NK cells transfused. However, all NK products containing allo-reactive NK cells killed the NK cell target K562, the MM cell line U266, and recipient MM cells when available. Post NK cell infusion there was a rise in endogenous interleukin-15 accompanied by increasing donor chimaerism. Donor chimaerism was eventually lost, which correlated with the emergence of potent host anti-donor responses indicating that the immunosuppressive properties of the conditioning regimen require further optimization. Further, blocking of inhibitory KIR-ligands with anti-human leucocyte antigen antibody substantially enhanced killing of MM cells thus highlighting the potential for modulating NK/MM cell interaction. Encouragingly, 50% of patients achieved (near) complete remission. These data set the stage for future studies of KIR-ligand mismatched NK cell therapy in the autologous setting. [ABSTRACT FROM AUTHOR]

Abstract: The allelic diversity and associated human leukocyte antigen (HLA) disparity of 1775 bone marrow recipients and their unrelated donors, matched for six of six (1361/1775,77%), five of six (397/1775, 22%), or four of six (17/1775, 1%) HLA-A, -B, -DR antigens, were retrospectively evaluated. The comprehensive HLA analysis included the class I (A, B, C) and II (DRB1, DQA1, DQB1, DPA1, DPB1) loci. Most (>66%) of the predominantly Caucasian study population carried one or two of five to seven common alleles at each HLA locus. In spite of this limited diversity, 29% of the six of six antigen-matched transplants carried allele mismatches at HLA-A, -B, and/or -DRB1, and 92% carried at least one allele mismatch at one of the eight HLA loci tested. Of the 968 HLA-A,-B,-DRB1 allele-matched pairs, 89% carried mismatches at other HLA loci, predominantly at DP loci. The substantially greater than expected HLA allelic disparity between donor and recipient suggests extensive haplotypic diversity and underscores the importance of enhancing approaches to mitigate the deleterious effect of HLA mismatches. [Copyright &y& Elsevier]

The full protein coding region of human immunodeficiency virus (HIV) genomes were sequenced using plasma collected from nine African-Americans prior to seroconversion and 7 to 28 days later. HIV mutations emerged in seven of these subjects at a genomewide rate of 2% per year. The location of nonsynonymous (NS) HIV mutations within these subjects was compared to their potential HLA.A and B types restricted CTL epitopes reported in the Los Alamos National Laboratory HIV immunology database. A statistically significant (P < 0.005) number of the early NS mutations (13.5%) were found within previously reported CTL epitopes. A virus sequencing and reported CTL epitopes database analysis therefore support a model where a significant proportion of very early nonsynonymous HIV mutations are selected by CTL. [ABSTRACT FROM AUTHOR]

Background: Biliary atresia (BA) is a neonatal cholestatic disease of unknown etiology. It is the leading cause of liver transplantation in children. Many similarities exist between BA and graft versus host disease suggesting engraftment of maternal cells during gestation could result in immune responses that lead to BA. The aim of this study was to determine the presence and extent of maternal microchimerism (MM) in the livers of infants with BA. Methods: Using fluorescent in situ hybridization (FISH), 11 male BA & 4 male neonatal hepatitis (NH) livers, which served as controls, were analyzed for X and Y-chromosomes. To further investigate MM in BA, 3 patients with BA, and their mothers, were HLA typed. Using immunohistochemical stains, the BA livers were examined for MM. Four additional BA livers underwent analysis by polymerase chain reaction (PCR) for evidence of MM. Results: By FISH, 8 BA and 2 NH livers were interpretable. Seven of eight BA specimens showed evidence of MM. The number of maternal cells ranged from 2-4 maternal cells per biopsy slide. Neither NH specimen showed evidence of MM. In addition, immunohistochemical stains confirmed evidence of MM. Using PCR, a range of 1-142 copies of maternal DNA per 25,000 copies of patients DNA was found. Conclusions: Maternal microchimerism is present in the livers of patients with BA and may contribute to the pathogenesis of BA. [ABSTRACT FROM AUTHOR]

MAC or RTC followed by UCB donor allo-HSCT in children with malignant and non-malignant diseases is safe and effective (Geyer/Cairo, BJH 2011). However, concentration of CD34+ HPCs in UCB is low, leading to delayed hematopoietic reconstitution and high incidence of engraftment failure (Satwani/Cairo, BBMT 2013). HPDSCs are rich in HPCs, low in HLA Class I/II expression and T-cells, and have regenerative, anti-inflammatory, and immunosuppressive properties (Liao/Cairo, Stem Cells Trans Med 2018). To determine the safety and efficacy of HPDSCs plus UCB for allo-HSCT in children. UCB with TNC ≥ 5 × 107/kg (4/6 HLA match) or ≥ 3.5 × 107/kg (5-6/6 HLA match) were included. Patients received MAC or RTC followed by UCB plus HPDSC infusion. GVHD prophylaxis consisted of tacrolimus and MMF as previously described (Bhatia/Cairo, BBMT 2009). Twenty-eight patients ≤18 years were enrolled, 15 males. Mean age± SD was 6.8±5.5 years, (4 months-12 years). There were 12 patients with non-malignant diseases including ALD (2), CAT (1), CGD (1), SCID (2), DC (1), CN (1), SAA (2), LCH (1), and SDS (1) and 16 patients with malignant diseases including B-ALL- CR1 (4), B-ALL - CR2 (4), T-ALL – CR1 (1), AML-CR1 (4), JMML-CR1 (1), TLL - CR1 (1), and BL - CR2 (1). There were 13, 9, and 5 patients with 6/6, 5/6, and 4/6 HLA match, respectively. Mean UCB TNC±SD and CD34+ cell dose±SD infused were 0.77±0.5 × 108/kg and 0.48±0.59 × 106/kg, respectively. Mean HPDSC TNC±SD and CD34+ cell±SD dose were 0.96±3.51 × 108/kg and 0.05±0.05 × 106/kg, respectively. There were no SAEs associated with HPDSC infusions. Four patients were withdrawn for administration of alternative therapy after engraftment failure (3) or relapse (1). Probability of neutrophil engraftment by day 42 was 78.6%, median day 22 (13-53). Probability of platelet engraftment by day 100 in neutrophil engrafted patients was 86.4%, median day 42 (35-98) (Figure 1). Mean UCB chimerism was 92, 99, 96 and 99% at day 30, 60, 100 and 180, respectively. Average HPDSC chimerism was <1% at day 30 and not detected beyond day 60. Probability of grade 2-4 and 3-4 aGVHD by day 100 were 18.2% and 13.6%, respectively. Of patients without grade 2-4 aGVHD, normalization of CD3+, CD19+, and CD56+ cells occurred by day 100, and CD8+ and CD4+ cells by day 270. Probability of OS at day 180 was 86.9%. Deaths occurred due to adenovirus (3) and RSV (1). One of 16 patients with malignant disease relapsed by day 180. These results suggest that UCB plus HPDSCs for Allo-HSCT is safe and well tolerated. Median day to platelet engraftment was lower than previously reported using UCB alone (Geyer/Cairo.BJH 2011). Probability of Grade 2-4 aGVHD was lower than previously reported using UCB alone, possibly due to the immunomodulatory effect of HPDSCs (Geyer/Cairo.BJH 2011). A larger cohort and longer follow-up is required to determine clinical significance. [ABSTRACT FROM AUTHOR]

Background Despite high cure rates for children, adolescents and young adults (CAYA) with mature B-cell non-Hodgkin lymphoma (B-NHL) (Cairo, JCO, 2012), the results are dismal in those with relapsed/refractory (r/r) disease following reinduction therapy with myeloablative conditioning (MAC) and autologous stem cell transplantation (AutoSCT) (Cairo, BBMT , 2013). Sequential MAC AutoSCT and reduced intensity conditioning (RIC) allogeneic stem cell transplantation (AlloSCT) has achieved 59% 10-year event-free survival (EFS) in CAYA with Hodgkin (Satwani/Cairo, Leukemia , 2015). The addition of Y-ibritumomab tiuxetan to an RIC based regimen prior to AlloSCT in a cohort of adults with high risk B-NHL was proven to be safe and efficacious (Boubdallah, Annals of Oncology, 2015) and may further improve outcomes. Objective To investigate the safety and efficacy in CAYA with poor risk r/r B-NHL of sequential MAC AutoSCT followed by RIC AlloSCT with or without targeted radioimmunotherapy. Design/Methods CAYA patients with poor risk r/r mature B-NHL who underwent MAC AutoSCT followed by RIC AlloSCT ± targeted radioimmunotherapy are included in this study. Twelve of thirteen patients with chemo-sensitive disease underwent sequential MAC AutoSCT followed by RIC AlloSCT (Fig 1). Six patients received radioimmunotherapy with Yttrium-90 ibritumomab tiuxetan prior to MAC. In addition to EFS, patients were assessed for time to hematological recovery, graft failure, whole blood chimerism, aGVHD ≥ Gr 2 and extensive chronic GVHD. Results Thirteen patients with a mean age of 15.3 years and mean follow-up of 48 months were analyzed. Median time to neutrophil and platelet engraftment is 18.8 and 36.4 days, respectively (Fig. 2). Whole blood chimerism at D+100 is 98.4 ± 1.5 %. Eleven patients are in complete remission with an EFS of 91% (Fig. 3). The transplant-related mortality was 0% and no graft failures developed. Conclusions CAYA with r/r B-NHL receiving MAC AutoSCT, targeted radioimmunotherapy, and RIC AlloSCT can achieve long-term EFS. The combination of radioimmunotherapy comprised of Yttrium-90 ibritumomab tiuxetan with MAC AutoSCT was safe and effective in our cohort. A potential graft versus lymphoma effect may explain the favorable outcomes in this cohort of patients with otherwise dismal outcomes. [ABSTRACT FROM AUTHOR]