Unrelated Allogeneic Hematopoietic Stem Cell Research Articles

Comparing the Outcomes of Matched and Mismatched Unrelated Allogeneic Hematopoietic Stem Cell Transplantation with Different Anti-Thymocyte Globulin Formulations: A Retrospective, Double-Centre Experience on Behalf of the Polish Adult Leukemia Group.

Despite notable advancements in immunotherapy in the past decades, allogeneic hematopoietic stem cell transplantation (allo-HCT) remains a promising, potentially curative treatment modality. Only a limited number of studies have performed a direct comparison of two prevalent rabbit anti-thymocyte globulin (r-ATG) formulations-specifically, Thymoglobuline (ATG-T, formerly Genzyme) and Grafalon (ATG-G, formerly Fresenius). The primary objective of our retrospective analysis was to compare the outcomes of adult patients undergoing matched or mismatched unrelated donor (MUD/MMUD) allo-HCT, with a graft-versus-host disease (GvHD) prophylaxis based on either ATG-T or ATG-G. A total of 87 patients who had undergone allo-HCT between 2012 and 2022 were included. We observed no significant differences between ATG-T and ATG-G concerning the occurrence of acute graft-versus-host disease (aGvHD), regardless of its severity. Conversely, chronic graft-versus-host disease (cGvHD) occurred less frequently in the ATG-T group compared to the ATG-G group (7.5% vs. 38.3%, p = 0.001). The negative impact of ATG-G on cGvHD was confirmed by multivariate analysis (HR 8.12, 95% CI 2.06-32.0, p = 0.003). Patients treated with ATG-T manifested a higher incidence of cytomegalovirus (CMV) reactivations (70% vs. 31.9%, p < 0.001), with a shorter time between transplant and CMV (<61 days, 77.8% vs. 33.3%, p = 0.008) and a higher median CMV copy number (1000 vs. 0, p = 0.004). Notably, despite a higher occurrence of CMV reactivations in the ATG-T cohort, most patients were asymptomatic compared to ATG-G (85.7% vs. 43.8%, p = 0.005). By multivariate analysis, only aGvHD had an influence on CMV reactivations (HR 0.18, 95% CI 0.04-0.75, p = 0.019). Finally, we observed no significant differences in terms of 5-year overall survival (OS) and 3-year relapse-free survival (RFS) while comparing ATG-T and ATG-G (32.0% vs. 40.3%, p = 0.423; 66.7% vs. 60.4%, p = 0.544, respectively).

Integrative Single-Cell Tracking of Clonal Evolution, Leukemia Phenotypes and Donor Engraftment Following Allogeneic Stem Cell Transplant Using Mitochondrial DNA Mutations

Mitochondrial DNA (mtDNA) mutations can distinguish cells from unrelated individuals and their spectrum per patient sample can evolve following therapeutic bottlenecks. As such, these natural barcodes can potentially enable integrated single cell tracking of chimeric cellular populations and clonal evolution following unrelated allogeneic hematopoietic stem cell transplantation (HSCT). However, the feasibility of mtDNA-based donor-recipient deconvolution or identification of leukemia-specific phenotypes and the extent of co-evolution with somatic mutations remains unknown. If confirmed, post-transplant monitoring using mtDNA mutations could enable detection of early post-HSCT relapse and provide qualitative information on leukemia phenotypes, clonal evolution, or residual donor engraftment via a combined single cell assay. To investigate the extent of co-evolution of somatic nuclear mutations with mtDNA mutations, we generated 33,796 single cell DNA sequencing profiles (Tapestri) from 3 sample pairs of circulating chronic lymphocytic leukemia (CLL) collected before and after HSCT. The samples were characterized using a primer panel (n=67 nuclear and 21 mtDNA) targeting single nucleotide variants previously identified by whole-exome sequencing. We detected 8 mtDNA mutations that defined CLL subclones together with a median of 14 (8-19) somatic mutations from these cases. Clonal shifts defined by somatic mutations discernable pre- or post-HSCT tracked with analogous changes in mtDNA mutations and included clonal replacement, selection of a resistant subclone or skewing of CLL subclones. We thus provide clear evidence of co-segregation between somatic nuclear and mtDNA mutations. To assess the sensitivity of mtDNA-based donor-recipient deconvolution, we performed an in-silico titration and spiked 1-1,000 single cell mtDNA profiles (mtscATAC-seq) from one CLL case ('CLL4') into 7,579 profiles from another ('CLL5'). Overall, we recovered 98.3-100% of CLL4, identifying up to 1 in 7,579 cells (0.13%). Only 123 cells (1%) failed deconvolution, due to insufficient mtDNA coverage. In an in-vitro titration of expanded T cells (donor1) with peripheral blood mononuclear cells (donor2) at ratios of 1:3, 1:30 and 1:300, we recovered 1,449 of 5,345 (27%), 150 of 4,262 (3.5%) and 14 of 4,381 (0.3%) T cells of donor1. In sum, with current sequencing throughput, mtDNA-based donor-recipient deconvolution was assessed to have a sensitivity of ~0.1%. To determine if mtDNA-based deconvolution can track early AML relapse and identify leukemia phenotypes, we analyzed peripheral blood and bone marrow of 4 patients with disease recurrence 87-185 days post-HSCT and subsequent reinstatement of remission 105-184 days after tapering of immunosuppression (IST). We obtained 19,143 ATAC with select antigen profiling by sequencing (ASAP-seq) profiles at incipient relapse (pre-IST) and following response to IST (post-IST). Donor-recipient deconvolution detected recipient-derived cells in progenitor, erythroid and monocytic populations pre-IST but no recipient-derived cells post-IST, consistent with elimination of AML. Overall, chromatin accessibility of donor- and recipient-derived cells was very similar, reflecting that AML recapitulates hematopoietic differentiation states. Nevertheless, we observed differences in accessibility of genes such as IL1B, CD36, chemokine or homeobox protein genes in recipient- compared to donor-derived cells. Together, mtDNA-based donor-recipient deconvolution reflected clinical responses and identified leukemia-specific chromatin accessibility profiles. Finally, we tracked clonal evolution and donor-derived hematopoiesis in two non-responder cases of overt AML relapse following 3-10 cycles of decitabine and ipilimumab (NCT02890329). We defined 12 and 7 mtDNA-based AML subclones and observed contraction and expansion of subclones during treatment. Donor-derived non-T cells were exceedingly rare (12 of 10,708 [0.1%] and 34 of 5,863 [0.6%]), mainly of erythroid origin (12 and 23 cells) and disappeared during treatment. Thus, mtDNA mutations can monitor donor- and recipient-derived hematopoiesis and resolve short-term changes in AML subpopulations during therapy. As sequencing throughput improves, we envision single cell-based post-transplant monitoring as a powerful approach for guiding clinical decision making.

The Area Under Tacrolimus Concentrations on Day 14-28 Is the Independent Predictor of the Development of Chronic Gvhd in Patients without Severe Acute Gvhd after Unrelated Allogeneic HSCT

Introduction: In unrelated allogeneic hematopoietic stem cell transplantation (UR-SCT), chronic graft-versus-host disease (GVHD) is a critical complication that affects not only patients' quality of life but also post-transplant outcome. Acute GVHD is a major risk factor for the subsequent development of chronic GVHD. The combination of tacrolimus and short-term methotrexate (TAC+sMTX) has been widely used as a GVHD prophylaxis for UR-SCT in Japan. Previous reports have shown that tacrolimus blood concentrations early after transplantation are associated with the development of acute GVHD, but not with that of chronic GVHD. On the other hand, among UR-SCT recipients who did not develop severe acute GVHD, the relationship between tacrolimus blood concentrations and the development of chronic GVHD remains unclear. Methods: To examine the association between tacrolimus blood concentrations and post-transplant outcomes, the area under the tacrolimus concentration on day 0-14 (AUTC 0-14) and day 14-28 (AUTC 14-28) was calculated simply as the sum of the area of the trapezoid for the corresponding period ( Figure). Tacrolimus was initiated by continuous intravenous administration from day -1 in all patients, and no patients were switched to oral administration prior to day 28. Short-term methotrexate was administered at 10 mg/m 2 on day 1 and 7 mg/m 2 on day 3, day 6, and day 11. Among all 151 adult patients with hematopoietic malignancies who underwent first UR-SCT with GVHD prophylaxis of TAC+sMTX between 2010 and 2022 at the Jikei University Hospital, the following were excluded from the analysis: developing grade III-to-IV acute GVHD, using prednisolone or methyl-prednisolone ≥0.5 mg/kg within day 100, engraftment failure, death before day 100, and relapse before day 100. Results: A total of 68 patients were included in the analysis. Median age was 50.5 (range, 16-68) years. Twenty-seven (40%) patients had acute myeloid leukemia, and 18 (27%) had acute lymphoblastic leukemia. Fifty-five (81%) were in complete remission/chronic phase/early stage. The donor source consisted of 42 (62%) bone marrow transplantation (BMT), 20 (29%) cord blood transplantation (CBT), and 6 (9%) peripheral blood stem cell transplantation (PBSCT). BMT recipients transplanted from 22 (52%) HLA 8/8 matched donor, 19 (45%) HLA 7/8 matched donor, and one (3%) HLA 6/8 matched donor. CBT recipients transplanted from 15 (75%) HLA 4/6 matched donor and 5 (25%) HLA 5/6 matched donor. PBSCT recipients transplanted from 5 (83%) HLA 8/8 matched donor and one (17%) HLA 7/8 matched donor. Fifteen (22%) patients were administered additional low-dose anti-thymocyte globulin (ATG) as GVHD prophylaxis. Fifteen male patients transplanted from female donors (22%). Thirty-nine (57%) patients received myeloablative conditioning regimen. The median time from UR-SCT to neutrophil engraftment was 19 days (range, 11-34). Regarding acute GVHD, 46 patients (68%) developed none, 13 patients (19%) developed grade I, and 9 patients (13%) developed grade II. The median observation period for all 68 patients was 48.2 months (4.0 years). The 4-year cumulative incidence (CI) of chronic GVHD was 51%, of which 24% were moderate-to-severe. The CI of moderate-to-severe chronic GVHD was not associated with age, disease status, donor source, HLA incompatibility, ATG use, female to male, intensity of conditioning regimen, and grade I-to-II acute GVHD development. AUTC 14-28 &amp;lt;200 was the only risk factor (AUTC 14-28&amp;lt;200: 32% vs AUTC 14-28≥200: 11%; p=0.047). Multivariate analysis also showed that AUTC 14-28 &amp;lt;200 was the independent factor for development of moderate-to-severe chronic GVHD ( p=0.04). In all 68 patients, 4-year CI of relapse was 20%, 4-year CI of non-relapse mortality was 10%, 4-year GVHD-free, relapse-free, survival (GRFS) was 50%, and 4-year Overall survival was 80%, all of which did not differ between AUTC 14-28 &amp;lt;200 and AUTC 14-28 ≥200 groups. Conclusion: In UR-SCT, our data showed that AUTC 14-28 &amp;lt;200 may be an independent risk factor for developing moderate-to-severe chronic GVHD, even in patients who did not develop severe acute GVHD.

Improved Overall Survival of Patients Treated with Abatacept in Combination with a Calcineurin Inhibitor and Methotrexate Following 7/8 HLA-Matched Unrelated Allogeneic Hematopoietic Stem Cell Transplantation: Analysis of the Center for International Blood and Marrow Transplant Research Database

Improved Overall Survival of Patients Treated with Abatacept in Combination with a Calcineurin Inhibitor and Methotrexate Following 7/8 HLA-Matched Unrelated Allogeneic Hematopoietic Stem Cell Transplantation: Analysis of the Center for International Blood and Marrow Transplant Research Database

Stable pulmonary function after haploidentical stem cell transplantation with post-transplant cyclophosphamide: a single center experience

Prior studies have reported pulmonary function tests (PFT) before and after related and unrelated allogeneic hematopoietic stem cell transplantation (HSCT). However, limited data exist on the evaluation of lung function after haploidentical stem cell transplantation (HAPLO) with post-transplant cyclophosphamide (PTCY). We retrospectively reported the evaluation of PFTs at screening before HAPLO in 80 patients at 100 days and 1 year of follow-up. The proportion of surviving patients with available PFTs at 100 days and 1 year were 86% and 68%, respectively. During the follow-up period, four patients met the criteria for bronchiolitis obliterans syndrome and two for interstitial lung disease. Overall survival was 73% (95% CI 62–82%) at 2 years. We observed a significant reduction in diffusing capacity of the lungs for carbon monoxide (DLCO) corrected for the most recent hemoglobin concentration (DLCOc) at 100 days after HAPLO. However, an overall substantial stable pulmonary function was observed at 1 year.

Clinical impact of multiple DNA virus infections in nondepleted haploidentical and unrelated allogeneic hematopoietic stem cell transplantation.

Few studies have compared the clinical impact of multiple DNA-virus infections in haploidentical hematopoietic stem cell transplantation (haplo-HSCT) with posttransplant cyclophosphamide (PTCy) and unrelated donor allogeneic hematopoietic stem cell transplantation (UD-HSCT) with thymoglobulin, so we retrospectively analyzed viral infections in the first 6mo posttransplant in these scenarios. Fifty-nine patients underwent to haplo-HSCT, and 68 to UD-HSCT. The most frequent infection was cytomegalovirus (CMV) (76.3% in haplo-HSCT and 69.1% in UD-HSCT) (P=.878) and in the group of patients with CMV reactivation, maximal CMV viral load over 2500UI/ml correlated with worse overall survival-hazard ratio (HR) 1.93 (95% confidence interval [CI] 1.04-3.59) P=.03. The cumulative incidence of multiple DNA virus within 180d of posttransplant was 78.7% for one virus and 28.4% for two or more viruses with no difference regarding the type of transplant. Viral infections, age, and acute graft versus host disease (GVHD) grades II-IV were risk factors for worse overall survival in multivariate analyses: one virus HR 2.53 (95% CI 1.03-6.17) P=.04, two or more viruses HR 3.51 (95% CI 1.37-9) P<.01, age HR 1.03 (95% CI 1.02-1.05) P<.01 and acute GVHD II-IV HR 1.97 (95% CI 1.13-3.43) P=.01. Also, age over 50y HR 4.25 (95% CI 2.01-8.97) P<.001, second CMV reactivation or having both CMV and BK polyomavirus (BKV) HR 2.65 (95% CI 1.26-5.56) P=.01 and acute GVHD grades II-IV HR 2.23 (95% CI 1.12-4.43) P=.022 were risk factors for nonrelapse mortality in the multivariate analyses. In conclusion, multiple DNA-virus infections are frequent in both haplo-HSCT and UD-HSCT and a risk factor for worse overall survival.

First case report of a NUP98-PMX1 rearrangement in de novo acute myeloid leukemia and literature review

BackgroundThe nucleoporin 98 (NUP98)-paired related homeobox 1 (PMX1) fusion gene, which results from t(1;11)(q23;p15), is rare in patients with acute myeloid leukemia (AML). Currently, only two cases of chronic myeloid leukemia in the accelerated phase or blast crisis and three cases of therapy-related AML have been reported. Here, we first report a patient with de novo AML carrying the NUP98-PMX1 fusion gene.Case presentationA 49-year-old man diagnosed with AML presented the karyotype 46,XY,t(1;11)(q23;p15)[20] in bone marrow (BM) cells. Fluorescence in situ hybridization analysis using dual-color break-apart probes showed the typical signal pattern. Reverse transcription-polymerase chain reaction (RT-PCR) analysis suggested the presence of the NUP98-PMX1 fusion transcript. The patient received idarubicin and cytarabine as induction chemotherapy. After 3 weeks, the BM aspirate showed complete remission, and the RT-PCR result for the NUP98-PMX1 fusion gene was negative. Subsequently, the patient received three cycles of high-dose Ara-c as consolidation chemotherapy, after which he underwent partially matched (human leukocyte antigen–DP locus mismatch) unrelated allogeneic hematopoietic stem cell transplantation (HSCT). The follow-up period ended on September 30, 2020 (6 months after HSCT), and the patient exhibited no recurrence or transplantation-related complications.ConclusionThis is the first report of a patient with de novo AML carrying the NUP98-PMX1 fusion gene. The reported case may contribute to a more comprehensive profile of the NUP98-PMX1 rearrangement, but mechanistic studies are warranted to fully understand the role of this fusion gene in leukemia pathogenesis.

The impact of donor full-length KIR2DS4 in the development of acute and chronic GVHD after unrelated allogeneic HSCT.

Killer Ig-like receptor 2DS4 (KIR2DS4) is the most prevalent activating killer Ig-like receptor gene. It is divergent and encodes either full-length or deleted allele variants. The studies of donor killer KIR2DS4 in unrelated allogeneic hematopoietic stem cell transplantations were limited. KIR and HLA genotyping were determined in 75 pairs of Chinese pediatric hematologic malignancy patients. Among the 75 donor-recipient pairs, 77.3% (58/75) of the donors were positive for full-length KIR2DS4 and 22.7% (17/75) were negative. Patients who had donors positive for full-length KIR2DS4 had higher cumulative incidence of aGVHD than patients whose donor negative for full-length KIR2DS4 (86.2% versus 76.5%, P=.038). Multivariate analysis showed full-length KIR2DS4 was the significant factor for I-IV aGVHD (HR=2.166, 95% CI: 1.01-4.26, P=.025). Subgroup analysis showed that AML and CML patients who received donors negative for full-length KIR2DS4 have a higher cumulative incidences of cGVHD (75% vs 62%, P=.008). There were no significant effects of full-length KIR2DS4 on overall survival (P=.13), relapse-free survival (P=.14), CMV reactivation (P=.52), and relapse (HR=0.38, 95% CI: 0.09-1.6, P=.1875). Our findings indicated a significant correlation of donor full-length KIR2DS4 on aGVHD and cGVHD. These results suggested that combining KIR and HLA genotyping may help make a better sense of transplants in these patients.

The role of prospection in altruistic bone marrow donation decisions.

The decision to become an unrelated allogeneic bone marrow or hematopoietic stem cell (HSC) donor is a consequential and complex one. Although new registry members pledge to donate if asked in the future, significant proportions ultimately reconsider when they are notified as a potential match for a patient and are asked to undergo confirmatory typing (CT), resulting in many patients failing to receive transplants. We consider the roles of prospection, or thinking about the future, and ambivalence, or having mixed emotions about an event, in this phenomenon. Prospection theory dictates that distant and improbable events are construed more abstractly than near-term and probable events. We hypothesized that construals about donation in new registry members versus those asked to undergo CT would differ in accordance with these patterns, and that variation in construals would be associated with decisions about whether to proceed toward donation. In collaboration with the National Marrow Donor Program, we measured donation intentions and CT decisions in 516 new registry members and 213 members asked to undergo CT, respectively. Participants were asked to describe what they imagined would happen in the donation process. We found that the valence and heterogeneity with which registry members construed donation were significant predictors of donation-related decisions. Assuming the temporal ordering of cognitive processes, ambivalence about donation was a mediator of these relationships. Findings suggest that encouraging a focus on positive central features of marrow and HSC donation may reduce ambivalence and decrease attrition from the registry. (PsycINFO Database Record (c) 2020 APA, all rights reserved).

The role of HLA matching in unrelated donor hematopoietic stem cell transplantation for sickle cell disease in Europe.

We report the results of an analysis of unrelated allogeneic hematopoietic stem cell transplantations (HSCT) in 71 patients with sickle cell disease (SCD) transplanted in EBMT centers between 2005 and 2017. Median age was 9.3 years; graft type was bone marrow in 79% and peripheral blood in 21%. Recipient-donor HLA match at high resolution typing was 10/10 in 31, 9/10 in 20, and 8/10 in 4 patients; the other patients had intermediate resolution typing. The most frequent conditioning regimens were fludarabine-thiotepa-treosulfan (64%) or busulfan-cyclophosphamide (12%). Cumulative incidence of neutrophil engraftment was 92%; platelet engraftment was 90%. Eleven patients (15%) experienced graft failure. Grade II-IV acute graft-vs.-host disease (GvHD) was 23%; 3-year chronic GvHD was 23%. Three-year overall survival (OS) was 88 ± 4%. GRFS was 62 ± 6%. HLA matching was the most significant risk factor for OS: 3-year OS was 96 ± 4% in 10/10 group vs. 75 ± 10% in 9-8/10 (p = 0.042); GRFS was 69 ± 9% vs. 50 ± 12% (p = 0.114), respectively. In conclusion, unrelated donor HSCT is a valid option for SCD patients who lack an HLA-identical sibling donor, preferably in the context of clinical trials. Using a 10/10 HLA-matched unrelated donor yields better survival indicating that HLA matching is an important donor selection factor in this nonmalignant disease.

Absolute Lymphocyte Count (ALC) Less Than 100 Predicts Adverse Transplant Outcomes with Rabbit Thymoglobulin in Patients Undergoing Matched Unrelated Allogeneic Hematopoietic Stem Cell Transplantation

Introduction: Rabbit thymoglobulin, an in-vivo T-cell depleting agent, is widely used as a part of GVHD prophylaxis regimen. Current dosing of thymoglobulin is often weight based and does not consider patient related factors. This results in highly variable exposure of thymoglobulin. Although higher doses (&gt;7mg/kg) of thymoglobulin have shown to reduce the risk of GVHD, it is associated with increased rate of opportunistic infections and disease recurrence. Conversely, lower dose (2.5mg/kg) of thymoglobulin is associated with increased risk of GVHD. Thus, optimum dosing of thymoglobulin remains undefined. We hypothesized that recipient peripheral blood ALC on the first day of thymoglobulin infusion would interact with the dose of thymoglobulin administered and predict post-transplant outcomes. We plan to identify association of thymoglobulin dose with the ALC on the first day of thymoglobulin. Methods: We retrospectively evaluated clinical outcomes of adult patients (pts) who underwent matched unrelated donor AHSCT and received tacrolimus, mycophenolate (cellcept) and thymoglobulin as GVHD prophylaxis. Thymoglobulin was given at a total dose of 4.5mg/kg in divided fashion (0.5mg/kg on day -3, 1.5mg/kg on day -2 and 2.5mg/kg on day -1). The objectives were to determine rate of GVHD, overall survival (OS), relapse-free survival (RFS), relapse rate and non-relapse mortality (NRM) following AHSCT using Cox proportional hazard regression and competing risk models. Results: Between January 2005 and December 2017, 217 pts underwent AHSCT. The most common indications for AHSCT were AML (n=95, 44%), MDS (n=57, 26%), non-Hodgkin's lymphoma (n=23, 11%), and ALL (n=22, 10%). Median age of pts was 60 years (range, 18-79). All pts received peripheral blood stem cells. Ninety-eight pts (45%) received full intensity conditioning regimen and 119 pts (55%) received reduced intensity regimen. The median ALC on the first day of thymoglobulin administration was 200 K/cubic millimeter. The 6-month cumulative incidence rate (CIR) of grade III-IV acute GVHD was 14.8% and the 2-year CIR of chronic extensive GVHD was 35.4%. With a median follow up of 3.82 years for surviving patients, the 2-year RFS, OS, relapse and NRM were 50%, 57.1, 20.1%, and 30.2%, respectively. CMV and EBV reactivation rates were 37% and 11%, respectively. Four pts developed CMV disease. By our lowest ALC cutoff of 100 K/cubic millimeter, pts were divided into two groups (ALC ≤ 100 vs. ALC &gt; 100). Multivariable analysis revealed that ALC &gt; 100 was associated with significantly superior OS (HR 0.51, 95% CI 0.33-0.79, p=0.002), RFS (HR 0.49, 95% CI 0.33-0.74, p=0.001) and lower NRM (SHR 0.57, 95% CI 0.34-0.97, p=0.038) and marginally lower relapse rate (SHR 0.57, 95% CI 0.31-1.05, p=0.070). In addition, higher infused total nucleated cells was associated with higher NRM (SHR 1.70, 95% CI 1.02-2.83, p=0.041). No impact of disease risk index, KPS, conditioning regimen, infused CD34 cells on NRM, relapse, RFS or OS was observed. Conclusion: Our study indicates that ALC ≤ 100 is associated with adverse post-transplant outcomes when thymoglobulin dose of 4.5mg/kg is used for in-vivo T cell depletion. This finding may indicate that in pts with lower ALC, thymoglobulin dose may need to be adjusted to optimize its efficacy and avoid toxicities. In the future prospective studies, which evaluate dose reduction of thymoglobulin in pts with low ALC need to be planned to confirm these results. Disclosures Deol: Agios: Other: Advisory board; Novartis: Other: Advisory board; Kite: Other: Advisory board.

Abstract LB-052: Detection of rare, deleterious clonal mutations during unrelated allogeneic hematopoietic stem cell transplants using an error correction pipeline for NGS

Abstract While next-generation sequencing (NGS) has transformed our ability to characterize the genome, it is limited in detection of rare mutations due to a high error rate of ~0.5-2.0%. We have developed an error correction pipeline and previously demonstrated that our process is capable of detecting variants as rare as 1:10,000 or 0.0001 VAF. Using our error correction pipeline, we have recently identified leukemia-related hematopoietic clones in a cohort of young healthy bone marrow donors (median age 26). In the context of allogeneic hematopoietic stem cell transplantation (HSCT), we sought to determine whether these detected leukemia-related clones of donor origin selectively engraft and correlate with transplant-related morbidities in recipients post-HSCT. Genomic profiles of pre-transplant donor samples were compared to the genomic profiles of corresponding recipient samples post-HSCT. Results show that two-thirds of the healthy donor samples harbor deleterious hematopoietic clones and that these specific clones are significantly more likely to engraft compared to benign clones. We also found that 75% of recipients who had at least one persistently engrafted, deleterious mutation developed chronic GvHD versus 50% of those without persistently engrafted clones with deleterious mutations. In comparing the results from our error correction pipeline and conventional short tandem repeat (STR) testing for donor-patient chimerism, we showed that our method provides a highly sensitive approach to both screening for donors without deleterious clones and monitoring residual disease in recipients following hematopoietic stem cell transplants (HSCT). Furthermore, the clinical implications of these results warrant a large-scale study using our error correction pipeline to detect rare variants in HSCT. Citation Format: Wing Hing Wong, Andrew Young, Todd Druley. Detection of rare, deleterious clonal mutations during unrelated allogeneic hematopoietic stem cell transplants using an error correction pipeline for NGS [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr LB-052.

Comparison and correlation among in vitro and in vivo assays to assess cord blood quality according to delivery temperature and time after collection

Cord blood (CB) has been used as an alternative source for unrelated allogeneic hematopoietic stem cell transplantation. To determine which assay was useful for predicting the successful outcome of CB transplantation, CBs were grouped according to the temperature (4 °C, 24 °C, and 37 °C) and time (24, 48, and 72 h) after collection. The viability, early apoptosis, and colony forming units (CFUs) were ascertained for the total nucleated cells (TNCs) and CD34+ cells; in addition, the engraftment of infused CD34+ cells in NSG mice was determined. The viability of the TNCs and CD34+ cells and total CFUs were significantly decreased whereas the early apoptosis was significantly increased in the 72 h group at 37 °C compared to that of the 24 h group at 24 °C. The viability and early apoptosis of the TNCs correlated with those of CD34+ cells. In addition, the viability and early apoptosis correlated with the number of granulocyte/monocyte progenitor CFUs. In transplanted NSG mice, the frequency of human CD45+ cells decreased in the 72 h group at 24 °C compared to that of the 24 h group at 24 °C and was negatively correlated with early apoptosis of TNCs and CD34+ cells. This study demonstrated that the early apoptosis of TNCs and CD34+ cells constitutes a useful marker for predicting the engraftment of HSCs and may provide helpful data for standard assessment regarding CB quality by analyzing the correlation between in vitro and in vivo assays using NSG mice.

A Pilot Study: Identification and Reduction of Barriers for Unrelated Allogeneic Hematopoietic Stem Cell Transplantation in Patients with High-Risk Hematologic Malignancies

The timeliness to Hematopoietic Stem Cell Transplant (HSCT) as a potential curative treatment for patients with high-risk hematologic malignancies such as acute leukemias, refractory disease, progressive disease, or other poor prognostic disease specific indications has been well established [3]. Timing is crucial from date of diagnosis, initiation of induction therapy, donor identification and transplantation. Any delay can provoke unfavorable patient outcomes and reinforces the critical need to reduce barriers for timeline to transplant [1]. Unrelated allogeneic HSCT pose greater risks due to the complexity of donor barriers versus match/mismatched related donor transplants [1]. Key factors resulting in delayed unrelated donor transplantation include; poor donor match probabilities – lack of ethnic minority populations or patients with rare allelic haplotype associations, low resolution Human Leukocyte Antigen (HLA) typing in donor registry, limited donor availability, lack of donor health history information, unknown infectious disease markers results, etc. [4]. Other potential areas for significant delay include time requirements for allele level HLA resolution, final donor selection and donor workup process. Given the high-risk patient population, identified existing donor barriers and finite window of opportunity for favorable HSCT outcomes; our center proposed a pilot study in conjunction with the National Marrow Donor Program (NMDP) to reduce barriers for rapid donor identification, selection and workup. The main objective of the proposed study was to identify and select a workup ready unrelated donor within 14 days of search initiation. Selected high-risk patients were enrolled in the pilot program from September 2016 through March 2018 (N = 25). Throughout the pilot study our center was able to identify areas of process improvement within our collective transplant program. Process improvements were also established in collaboration with the NMDP and their respective donor centers and collection centers. Following the completion of the study, we retrospectively analyzed our center's transplant data from 2017 and compared the time to transplant for pilot study patients (n = 15) versus all primary unrelated donor transplants (n = 100) performed, with the exclusion of cord blood unit transplants. We were able to obtain donor confirmatory typing appointments with a median of 7 days from formal search initiation. We were also able to reduce the median days for formal search to workup for the pilot study donors to 28 days versus 56 days, and the median days for formal search to donor collection to 35 days versus 97 days. Although we did not meet our proposed primary objective of 14 days, our center was able to successfully reduce the time needed to identify, select, and collect an unrelated donor for transplantation using the expedited process.

Does matching for SNPs in the MHC gamma block in 10/10 HLA-matched unrelated donor-recipient pairs undergoing allogeneic stem cell transplant improve outcomes?

BackgroundMatching at the HLA-A, HLA-B, HLA-C, HLA-DRB1, and HLA-DQB1 loci is important in donor selection for patients undergoing unrelated allogeneic hematopoietic stem cell transplantation (ASCT). Additional matching across the MHC gamma region may further improve outcomes. MethodsThe MHC gamma region was retrospectively genotyped in 66 adult recipients of ASCT and their 10/10 matched unrelated donors. A chart review was performed to determine whether MHC gamma matching impacted survival, relapse, or graft-versus-host disease. ResultsOf 66 donor-recipient pairs, 26(39.4%) were gamma-type matches, 34(51.5%) were mismatches, and 6(9.1%) were “indeterminate.” Matching status was not associated with overall survival (p = 0.43), relapse (p = 0.21), acute GVHD (p = 0.43), severe aGVHD (p = 0.31), or chronic GVHD (p = 0.23) in univariate analyses, nor in multivariate analyses (p = 0.28, 0.13, 0.29, 0.16, and 0.67, respectively), with or without adjusting for HLA-DPB1 matching status. ConclusionsIn our single institution study, gamma-type matching status was not associated with outcomes of adult ASCT recipients.

Unrelated Allogeneic Stem Cell Transplantation in a Patient with Chronic Myeloid Leukemia in Blast Crisis

Abstract Chronic myeloid leukemia (CML) is a clonal myeloproliferative disorder, which can involve the hematopoietic stem cell or early progenitor cells, without the loss of their capacity to differentiate. Typically, CML has three clinical phases: a chronic phase, an accelerated phase, and an aggressive transformation in blast crisis, analogous to acute leukemia. The following article presents the case of a 49-year-old patient diagnosed with Philadelphia-negative CML in blastic transformation, where after multiple conventional acute leukemia induction chemotherapy regimens an unrelated allogeneic hematopoietic stem cell transplant was performed.

Distribution of donor-specific aKIR after unrelated allogeneic hematopoietic stem cell transplantation

目的分析非血缘异基因造血干细胞移植（allo-HSCT）后可供检测的供者特异性激活性杀伤细胞免疫球蛋白样受体（aKIR）基因的分布、比例及在临床中的应用价值。方法采用序列特异性引物聚合酶链反应（PCR-SSP）方法，回顾性分析216对供受者KIR基因分型，探讨可供检测的供者特异性aKIR的临床价值。结果在216例患者接受非血缘HSCT后可检测到供者特异性KIR基因为53.7%（116/216），在供受者KIR基因型不合中占78.3%（112/143），在供受者KIR基因型相合中占5.5%（4/73）。116例患者可检测到供者特异性KIR，99.1%（115/116）为aKIR基因。55对供受者KIR基因型为Bx-AA，可分别检测Bx1基因型中KIR3DS1、KIR2DL5A、KIR2DS5、KIR2DS1；Bx2基因型中KIR3DS1、KIR2DL5A、KIR2DS3、KIR2DS1；Bx3基因型中KIR2DS2、KIR2DL2；Bx4基因型中KIR2DS2、KIR2DL2、KIR3DS1、KIR2DL5A、KIR2DS5、KIR2DS1。44对供受者AA-AB不合中，有16对可检测供者特异性的KIR2DS4（FUL）基因。在143对供受者KIR基因型不合中，可检测供者特异性KIR基因频率由高到低分别为KIR2DS1（35.7%）、KIR3DS1（32.9%）、KIR2DS5（29.4%）、KIR2DS4（FUL）（25.9%）、KIR2DL2（25.2%）、KIR2DS2（24.5%）、KIR2DS3（21.7%）、KIR3DL1（8.4%）。结论非血缘allo-HSCT后可检测的供者特异性aKIR基因主要分布在供受者KIR基因型不合中，且因供受者KIR基因型不同而有差异，但在频率较高的KIR-AA、Bx1、Bx2、Bx3、Bx4中有供者特异性较高的aKIR，其为研究aKIR基因对移植预后的影响奠定了实验基础。

Effects of IL10-592 locus of AA genotype on the incidence of aGVHD and survival after HLA-matched unrelated allogeneic hematopoietic stem cell transplantation

目的研究供患者IL10基因-592 (rs1800872）单核苷酸多态性位点（SNP）不同基因型对HLA全相合无关供者异基因造血干细胞移植（allo-HSCT）预后的影响。方法104对HLA全相合供患者和100名健康人的DNA样本，均采用Sanger法基因测序技术检测IL10-592位点SNP，并结合临床资料分析不同基因型对allo-HSCT各预后因素的影响。结果当供患者IL10-592位点基因型相同且分别为AA/AA、AC/AC、CC/CC时，移植后Ⅲ~Ⅳ度急性移植物抗宿主病（aGVHD）发生率分别为47.1%、3.7％和0，三组间差异有统计学意义（P=0.002）。当供患者IL10-592位点基因型不同，且患者为AA或供者为AA基因型时，不同基因型组合Ⅲ~Ⅳ度aGVHD发生率差异均有统计学意义（P=0.046，P=0.041）。当患者IL10-592位点为AA、AC、CC基因型时，移植后Ⅲ~Ⅳ度aGVHD发生率分别为27.8%、10.2%、11.1%（P=0.072）；肠道aGVHD的发生率分别为22.2%、5.1%、11.1%（P=0.040）；2年总生存（OS）率分别为48.2%、75.1%、85.7%（P=0.002）；2年无病生存（DFS）率分别为48.5%、66.3%、76.2%（P=0.045）。当供者IL10-592位点为AA、AC、CC基因型时，患者Ⅲ~Ⅳ度aGVHD发生率分别为26.5%、8.9%、0（P=0.024）；肠道aGVHD发生率分别为20.4%、4.4%、0（P=0.026）。多因素分析结果提示患者或供者IL10-592位点AA基因型组移植后有较高Ⅲ~Ⅳ度aGVHD发病风险（OR=3.3，P=0.049；OR=3.9，P=0.043）。而患者或供者IL10-592位点为AA、AC、CC不同基因型时，对慢性GVHD发生率和复发率均无明显影响。结论在HLA-10/10全相合无关供者allo-HSCT中，患者和（或）供者IL10-592位点AA基因型是allo-HSCT后发生较高Ⅲ~Ⅳ度aGVHD和较低OS、DFS率的不利因素。

Decreasing the Search Timeframe and Improving Transplant Center Satisfaction for Patients Receiving an Unrelated Allogeneic Hematopoietic Stem Cell Transplant

Decreasing the Search Timeframe and Improving Transplant Center Satisfaction for Patients Receiving an Unrelated Allogeneic Hematopoietic Stem Cell Transplant

T Cell Replete HLA- Haploidentical Donor Transplantation (HIDT) with Post-Transplant Cyclophosphamide (pTcy) Is an Effective Salvage for Patients Relapsing after a Matched Sibling or a Matched Unrelated Donor Transplantation

▪Objective:Relapse of high risk hematologic malignancies remains the major cause of mortality after matched sibling and matched unrelated allogeneic hematopoietic stem cell transplantation (HSCT). A second transplantation using the same donor or another fully matched donor yielded similar results with no clear advantage of choosing a newly matched donor (1). The purpose of this analysis was to evaluate the efficacy of HIDT with pTcy as a second HSCT among patients with high risk hematologic malignancies relapsing after a matched sibling or a matched unrelated donor.Methods and Population:All consecutive patients (n=20) who underwent a HIDT using ptCy at our center as a second allogeneic transplant for relapse of malignancy following a prior HLA-matched transplant were included in this retrospective analysis. Patient, disease and transplant related data was obtained from our institutional BMT database where it had been prospectively documented. Survival and disease-free survival (DFS) were estimated using the Kaplan-Meier method, Relapse and non-relapse mortality (NRM) were treated as competing risks. GVHD was prospectively documented and graded.Results:Patients (male n=13, female n=7) had a median age of 54 years (range 21-64). The median time from the first to the second HSCT was 20.7 months (range 2.7-65.8 months). 10 patients had AML/MDS, 6 ALL, 2 CLL and 2 myeloproliferative syndrome. Grafts from the first HSCT were 50% matched related (n=10) and 50% matched unrelated (n=10). The median number for HLA mismatches among HIDT recipients was 5/10 (range 4/10-8/10). All patients received cytoreductive therapy prior to the HIDT with 12 (60%) achieving a CR and 8 (40%) with active disease at the time of conditioning regimen initiation for HIDT. The conditioning regimen for HIDT was myeloablative in 3 patients (15%) with fludarabine/high dose TBI/pTcy in 2 (10%) patients and flu/busulfan/Cytoxan in 1 patient (5%) and non-ablative/reduced intensity (flu/low dose TBI/Cytoxan n=17; in 18 (90%) patients. All patients received pTcy and tacrolimus plus mycophenolate for graft versus host disease prophylaxis.All patients achieved sustained engraftment with median times to neutrophil and platelet engraftment of 17.5 (14-44) days and 32 (15-99) days respectively. The cumulative incidences (CI) of grade II-IV and grade III-IV acute GVHD at 180 days were 36% and 10% respectively. The CI of moderate-severe chronic GVHD was 13% at 1 year post HIDT. At a median follow-up of X months, The probability of overall survival, DFS, NRM and relapse post HIDT were 52%, 39%, 29% and 33% at 1 year and 34%, 31%, 29% and 40% at 3 years respectively.Conclusions:HIDT is an effective strategy to treat relapsed hematologic malignancies after a matched sibling or matched unrelated donor HSCT. Further and larger cohorts to confirm these observations are warranted.Table 1Survival Estimates6 months1 year3 yearsOS72%52%34%DFS53%39%31%NRM22%29%29%Relapse25%33%40%Mod-severe chronic GVHD5%13%13%Grade II-IV acute GVHD36%Grade III-IV acute GVHD10%1. Christopeit M, Kuss O, Finke J, Bacher U, Beelen DW, Bornhauser M, et al. Second allograft for hematologic relapse of acute leukemia after first allogeneic stem-cell transplantation from related and unrelated donors: the role of donor change. J Clin Oncol. 2013;31(26):3259-71. [Display omitted] [Display omitted] DisclosuresNo relevant conflicts of interest to declare.