Year Of Hematopoietic Cell Transplantation Research Articles

SCD Dyslipidemia Normalizes Long-Term Following Nonmyeloablative Hematopoietic Cell Transplantation

Dyslipidemia is common in patients with sickle cell disease (SCD). Individuals with SCD have a unique type of dyslipidemia. This SCD dyslipidemia (hypocholesterolemia subtype) is characterized by low total cholesterol (TC), low-density lipoprotein cholesterol (LDL-c), and high-density lipoprotein cholesterol (HDL-c), and normal triglycerides (TG). This SCD dyslipidemia state is theorized to be cardioprotective regarding atherosclerotic risk due to the hypolipidemic condition. Hematopoietic cell transplantation (HCT) is a potentially curative therapy for SCD. Nonmyeloablative HCT has been employed at the National Institutes of Health (NIH) and internationally with good results. Long-term survivors of HCT, specifically for hematologic malignancies, are at increased risk for dyslipidemia (hypercholesterolemia subtype), thus increasing atherosclerotic risk long-term. There are no studies investigating the short or long-term effects of HCT on SCD dyslipidemia. Therefore, we report a novel study to characterize lipid profiles at baseline and after HCT for SCD. This cohort study analyzes data from patients who received their first nonmyeloablative HLA-matched sibling or haploidentical HCT for SCD at the NIH from May 2009 to December 2021. All patients received sirolimus as GVHD prophylaxis. Total cholesterol, HDL-c, LDL-c, and triglycerides were collected pre-HCT, one-year post-HCT, and annually thereafter via a fasting serum-based lipid panel (median follow-up of 4 years). Data were analyzed using linear generalized estimating equation regression models to measure the influence of factors such as year of HCT, sirolimus use, gender, age, and graft failure on TC, LDL-c, HDL-c, and TG levels. A total of 116 patients were included in this analysis. There were 72 male and 44 female patients. The median age was 31 (range 10 to 64) years. 90% of the patients had Hb-SS, 3% Hb-SC, 5% Hb-Sβ 0, and 2% Hb-Sβ +. Overall survival is 87%, and 19% experienced graft failure. The median time on sirolimus post-HCT was one year. Baseline, one-year, and two-year mean (25th, 75th percentile) values, respectively, for the TC, LDL-c, HDL-c, and TG are as follows: TC [130.7 (107.0, 147.0), 183.2 (144.5, 220.0), 175.2 (144.5, 209.0)], LDL-c [72.5 (50.0, 87.0), 109 (73.5, 130), 104.2 (75.5, 128.0)], HDL-c [32.3 (23.8, 39.3), 49.4 (38.0, 55.5), 49.2 (41.5, 58.0)] and TG [127.3 (88.5, 156.5), 125.9 (87.0, 153.5), 112.6 (72.0, 133.5)]. Generally, the first-year post-HCT changes were maintained annually thereafter. (Figure 1). According to linear regression modeling, the change in TC, LDL-c, HDL-c, and TG at one-year post-HCT was +50.3 mg/dL (p<0.0001), +36.4 mg/dL (p <0.0001), +20.4 mg/dL (p<0.0001) and -26.5 mg/dL (p<0.0001), respectively. For failed grafts, the estimated changes after one-year post-HCT in TC, LDL-c, HDL-c, and TG were +6.5 mg/dL (p=0.45), -2.1 mg/dL (p=0.78), +14.8 mg/dL (p<0.0001), and -28.0 (p=0.03), respectively. The use of sirolimus only resulted in a significant change in TG (+32.8 mg/dL (p = 0.004)). Age had statistically significant changes only on TC (+1.08 mg/dL for a one-year change in age, p=0.005) and LDL-c (+0.73 mg/dL for a one-year change in age, p=0.03). There were no significant differences in TC, LDL-c, HDL-c, and TG levels (p>0.05) based on gender and HCT type. To summarize, HCT with sustained grafts led to significant rises in TC, LDL-c, and HDL-c and a decline in TG from baseline to one-year post-HCT, resulting in the normalization of lipid profiles. These changes were maintained annually thereafter. Graft failure most notably resulted in TC and LDL-c level declines back to pre-HCT baseline (Figure 2), while HDL-c and TG levels did not completely revert to baseline values. Sirolimus effects were significant on TG levels alone. These findings suggest that the mechanism underlying SCD dyslipidemia is corrected with the reversal of SCD. Long-term follow-up studies are indicated to assess patients' risk for atherosclerosis and adverse cardiac outcomes.

Impact of Age on Outcome in Newly Diagnosed Multiple Myeloma Patients Undergoing Upfront Autologous Hematopoietic Cell Transplantation from the Worldwide Network for Blood and Marrow Transplantation Global Study

Background ： Induction therapy with proteasome inhibitors and immunomodulatory agents followed by autologous hematopoietic cell transplantation (HCT) is considered standard of care in front line multiple myeloma (MM) treatment. Utilization of autologous HCT is increasing worldwide in younger and older patients in light of improvements in supportive care and infrastructure. However, global perspectives on patterns of patient age and the impact of age on outcomes in this population are scarce. In the current analysis of global registry data, we focused on the age distribution and the association of age with outcomes after HCT worldwide. Methods: Data were provided by the Worldwide Network for Blood and Marrow Transplantation through the European Society for Blood and Marrow Transplantation (EBMT), the Center for International Blood and Marrow Transplantation (CIBMTR), the Australia and New Zealand Transplant and Cellular Therapy Registry (ANZTCTR), the Asian Pacific Blood and Marrow Transplant Group (APBMT), the Eastern Mediterranean Blood and Marrow Transplant Group (EMBMT), the Latin American Bone Marrow Transplant group (LABMT), and the Ottawa hospital myeloma registry. The study included newly diagnosed MM patients transplanted between 2013 and 2017. The primary endpoint was overall survival (OS) and secondary endpoints were progression-free survival (PFS), incidence of relapse, and non-relapse mortality (NRM). The probability of OS and PFS was estimated based on the Kaplan-Meier method and differences were analyzed using the log-rank test. The incidences of relapse and NRM were modeled using the crude cumulative incidence estimator and compared between groups with Gray's test. Multivariate analyses were performed using Cox (cause-specific) proportional hazards models including a random effect for country. Age at HCT was modeled as a categorical variable (18-39, 40-64, 65-69, 70-74, and ≥75 years). Models further included patient sex, year of HCT, stage of disease at HCT, Karnofsky score, myeloma subclassification, conditioning dosage, interval between diagnosis and HCT, HCT comorbidity index, ISS at diagnosis, and cytogenetic risk score. Results: In total, 61,725 patients were included in this study; 37,459 (60.1%), 16,217 (26.3%), 3,164 (5.1%), 3,122 (5.1%), 543 (0.9%), 524 (0.8%), 339 (0.5%), 188 (0.3%), and 169 (0.3%) from EBMT, CIBMTR, ANZTCTR, Japan (APBMT), EMBMT, Taiwan (APBMT), LABMT, Ottawa, and Malaysia (APBMT), respectively. The median age at HCT was 60.8 (interquartile range: 54.6-65.8) years. The percentage of patients in the age groups 18-39, 40-64, 65-69, 70-74, and ≥75 years, varied considerably; 2%, 68.9%, 21.8%, 6.5%, and 0.8%, respectively (Table 1). The proportion of <40 years was higher in Malaysia, LABMT, and EMBMT (4-6%) compared to EBMT, CIBMTR, Japan, and ANZTCTR (2%). In contrast, the proportion of patients ≥65 years was higher in EBMT, CIBMTR, ANZTCTR, and Japan (>20%) compared to Malaysia, LABMT, and EMBMT (7-13%). The following patterns were observed in the age groups 18-39, 40-64, 65-69, 70-74, and ≥75 years, respectively. Melphalan 200 mg/m 2 for conditioning was used more frequently in younger patients (78.4%, 75.4%, 63.2%, 40.6%, and 28.3%, respectively). In 60.7% of the group ≥75 years, a lower dose of melphalan 140 mg/m 2 was chosen. OS was lower with older age (p<0.001) and was 86%, 83%, 81%, 78%, and 75% at 3 years, respectively (Figure and Table 1). PFS was similarly associated with older age (56%, 51%, 50%, 47%, and 45% at 3 years, respectively (p<0.001)). The cumulative incidence of relapse was not significantly different (15%, 16%, 15%, 16%, and 16% at 1 year, respectively (p=0.74)), but the cumulative incidence of NRM was higher with older age (p<0.001) and was 0%, 1%, 2%, 2%, and 4% at 1 year, respectively. On multivariate analysis, older age was associated with lower OS (overall p<0.0001), lower PFS (overall p=0.003), and higher NRM (overall p<0.0001), but not with the risk of relapse (overall p=0.79). Conclusions: There is considerable global variability in the age distribution of patients receiving HCT. Globally, 2% of patients receiving front line HCT for myeloma are aged <45 and 0.8% are >75 years. Advancing age was a significant risk factor for OS and PFS due to differences in NRM, but even in patients >75 years NRM was very low.

Post-Transplant Cyclophosphamide Eliminates Disparity in GvHD-Free, Relapse-Free Survival and Overall Survival between 8/8 Matched and 7/8 Mismatched Unrelated Donor Hematopoietic Cell Transplantation in Adults with Hematologic Malignancies

Background: Post-transplant cyclophosphamide (PTCy) has become a standard of care for graft-versus-host disease (GvHD) prophylaxis in recipients of human leukocyte antigen (HLA)-matched and mismatched unrelated donor (MMUD) allografts, generating new opportunities for successful hematopoietic cell transplantation (HCT) regardless of patient ancestry. The National Marrow Donor Program (NMDP)-sponsored 15-MMUD study, which used PTCy-based GvHD prophylaxis (PMID 3390526), demonstrated encouraging overall survival (OS) in adult patients receiving MMUD bone marrow grafts matched at ≤7/8 HLA alleles. Currently, the follow-up ACCESS study (NCT04904588) will determine if similar outcomes can be achieved using MMUD peripheral blood stem cell allografts. As part of its 5-year strategic plan, the NMDP aims to determine the extent of differences in GvHD-free, relapse-free survival (GRFS) between 8/8 and 7/8 URD allografts using PTCy and seeks to develop approaches over time to close the presumed gap in URD outcomes. Methods: The primary objective was to compare GRFS between 8/8 and 7/8 URD HCT using the Center for International Blood & Marrow Transplant Research (CIBMTR) database. After analyzing primary results, secondary objectives were added to compare GRFS, OS, and other clinical outcomes among 8/8 URD, 7/8 URD, and haploidentical-related donor (Haplo) HCT. The study included adult patients (age≥18y) with hematologic malignancies (ALL, AML, MDS) undergoing first URD or Haplo HCT between 2017-2020 using PTCy-based GvHD prophylaxis. Kaplan-Meier curves were used to estimate probability of GRFS and OS. Cox regression examined the independent effect of HLA match controlling for other clinical factors on outcomes referenced to 8/8 URD HCT. A priori clinically selected factors considered as possible confounders in the regression model included disease risk index, comorbidity risk, pre-HCT Karnofsky score, conditioning regimen intensity, graft source, donor/recipient CMV serostatus, year of HCT, donor/recipient age and race/ethnicity. Final models were stratified by factors violating the proportional hazards assumption. Factors were eliminated in a backwards fashion if p-values were >0.10 unless inclusion affected the hazard ratio (HR) of HLA match by more than 10%. Interactions were tested against a p-value of <0.01. Results: Table 1 shows demographics for the three patient cohorts: Haplo (n=2772), 8/8 URD (N=1517), and 7/8 MMUD (N=540). Notable differences among the cohorts included: 8/8 URD recipients had younger, predominantly Caucasian donors and were more likely to receive myeloablative conditioning. Haplo recipients had more donor/recipient CMV seropositivity and received more reduced intensity conditioning. Otherwise patient characteristics were similar. Contrary to our expectations, multivariable regression analysis (MVA) showed no significant differences in either GRFS or OS between recipients of 8/8 and 7/8 URD HCT at 1, 2 and 3-years post-HCT ( Figure 1). Outcomes, including relapse and NRM, between 8/8 and 7/8 URD HCT were similar irrespective of conditioning intensity. However, 8/8 URD HCT associated with lower two-year moderate/severe chronic GvHD than 7/8 URD [1.30 (1.00-1.68), p=0.049]. We next compared GRFS and OS among 8/8 and 7/8 URD and Haplo at 3y after HCT. On MVA, GRFS [HR 1.15 (1.04-1.26), p=0.005] and OS [HR 1.15 (1.03-1.29), p=0.013] were significantly better in 8/8 URD compared to Haplo HCT. Differences between 8/8 URD and Haplo appeared to be driven by significantly higher NRM [HR 1.46 (1.22-1.74), p<0.001)] and two-year moderate/severe chronic GvHD [HR 1.28 (1.07-1.54), p=0.007] in Haplo. No significant differences were seen in GRFS or OS at 3 years when comparing 7/8 URD to Haplo. Causes of death among donor types were similar with primary disease relapse/progression, infection and organ failure being the most frequent. Conclusions: Use of PTCy-based GvHD prophylaxis seems to have resolved previously observed differences in GRFS and OS between 8/8 and 7/8 URD HCT. HCT using an 8/8 URD HCT, if available, continues to be the best option for patients lacking a matched sibling donor. Further studies comparing Haplo to 7/8 URD HCT are warranted, but will require larger numbers of 7/8 URD HCT. Both mismatched donor sources substantially increase access to HCT for patients regardless of their ancestry.

Predictors of outcomes in hematopoietic cell transplantation for Fanconi anemia

Allogeneic hematopoietic cell transplantation (HCT) remains the only cure for the hematologic manifestations of Fanconi anemia (FA). We performed retrospective predictor analyses for HCT outcomes in FA for pediatric and young adult patients transplanted between 2007 and 2020 across three large referral institutions. Eighty-nine patients, 70 with bone marrow failure +/− cytogenetic abnormalities, 19 with MDS/AML, were included. Five-year overall survival (OS) was 83.2% and event-free survival (EFS) was 74%. Age ≥19, HLA mismatch and year of HCT were multivariable predictors (MVPs) for OS, EFS and treatment-related mortality (TRM). In the pediatric group, TCD was a borderline MVP (P = 0.059) with 5-year OS of 73.0% in TCD vs. 100% for T-replete HCT. The cumulative incidence of day 100 grade II-IV aGvHD and 5-year cGvHD were 5.6% and 4.6%, respectively. Relapse in the MDS/AML subgroup occurred in 4 patients (16%). Graft failure was seen in 9 patients (TCD 6/37 [16%]; T-replete 3/52 [5.7%]). Six patients developed malignancy after HCT. Survival chances after HCT for FA are excellent and associated with high engrafted survival and low toxicity. Age ≥19, HLA mismatch, year of transplant and ‘TCD in the <19 years group’ (although borderline) were found to be negative predictors for survival.

Integration of Palliative Care in Hematopoietic Cell Transplant: Pediatric Patient and Parent Needs and Attitudes.

Early integration of palliative care (PC) in hematopoietic cell transplantation (HCT) has demonstrated benefits, yet barriers remain, including perceived lack of patient/caregiver receptivity despite no data on attitudes toward PC and limited patient/caregiver reported outcomes in pediatric HCT. This study aimed to evaluate perceived symptom burden and patient/parent attitudes toward early PC integration in pediatric HCT. Following IRB approval, consent/assent, eligible participants were surveyed at St. Jude Children's Research Hospital including English-speaking patients aged 10-17, 1-month to 1-year from HCT, and their parents/primary-caregivers, as well as parent/primary-caregivers of living HCT recipients <age-10. Data were assessed for trends in response content frequencies, percentages, and associations. Eighty one participants, within one year of HCT, at St. Jude Children's Research Hospital were enrolled including: 36 parents of patients<age-10, 24 parents of patients ≥age-10, and 21 patients≥age-10. Most (65%) were 1-3 months from HCT. Analysis revealed high levels of perceived symptom suffering in the first month of HCT. 85.7% of patients and 73.4% of parents expressed that a-great-deal/a-lot of attention should be paid to quality-of-life from the start of HCT. Most respondents (patients-52.4/parents-50%) indicated they would likely have wanted early PC consult and very few (0%-patients/3.3%-parents) reported definite opposition to early PC involvement in HCT. Our findings suggest that patient/family receptivity should not be a barrier to early PC in pediatric HCT; obtaining patient reported outcomes is a priority in the setting of high symptom burden; and robust quality-of-life directed care with early PC integration is both indicated and acceptable to patients/caregivers.

Long-term health outcomes of allogeneic hematopoietic stem cell transplantation.

Fifty years of hematopoietic cell transplantation (HCT) has ushered in an exciting era of cellular therapy and has led to enormous progress in improving the outcomes of patients with both malignant and non-malignant hematologic disease. As the survival of transplanted patients has increased, so has the recognition of long-term complications related to this therapy. The goal of this review is to highlight some of the most common long-term complications of HCT. To this end, we have conducted a review of the published literature on the long-term complications of HCT encompassing the past 50 years. We have endeavored to include long-term complications reported in research articles, case series and case reports, reviews, and abstracts. We have focused primarily on adult allogeneic HCT, but have included some data from studies of pediatric allogeneic HCT as well. We have also prioritized the literature published in the last 15 years. Key data supporting the onset and prevalence of the most common long-term complications was extracted. While the list of long-term complications extracted and reported was comprehensive, it was not exhaustive. We have endeavored to highlight some of the most common long-term complications of HCT, the recognition and management of which constitutes an important part of HCT survivorship care.

Endothelial Complications of Hematopoietic Cell Transplantation for Sickle Cell Disease

Introduction Hematopoietic cell transplantation (HCT) is a curative therapy for sickle cell disease (SCD), with especially favorable outcomes in young patients from HLA-identical donors. Unfortunately, HCT is associated with endothelial injury syndromes (EIS), including veno-occlusive disease/sinusoidal obstruction syndrome (VOD/SOS), transplant-associated thrombotic microangiopathy (TA-TMA), and also acute graft-versus-host disease (GVHD), that increase transplant risk. This is further complicated by hemolysis-mediated endothelial dysfunction in patients with SCD. The impact of EIS in this population is not certain. We thus sought to better evaluate endothelial complications of HCT for SCD in a large, international registry. Methods We examined de-identified records of HCT for SCD that were retrieved from data on patients transplanted between 1991 and 2020 in the United States submitted to the Center for International Blood and Marrow Transplant Research (CIBMTR) obtained through curesickle.org. Patients were followed longitudinally until death, loss to follow-up, or last contact through June 2021 at 3, 6, 12, and 24 months after HCT, and then every 2 years. Donors included HLA-matched siblings, haploidentical relatives, and HLA-matched and HLA-mismatched unrelated donors. We examined overall survival, event-free survival, and acute and chronic GVHD. Cox regression models were used to examine for risk factors associated with TMA and VOD. In addition, one-factor (univariate) analysis was used to identify factors associated with higher risk complications. Results A total of 1641 unique patients underwent a first allogeneic HCT between 1991 and 2020, with a median year of HCT of 2014. Of HCT recipients, 67.7% were below the age of 18 years at HCT and 74.7% had Karnofsky performance score ≥ 90. Acute GVHD grades II-IV developed in 18.3% and 22.3% developed chronic GVHD. Graft failure was reported in 17.6% following HCT, which was from an HLA-identical sibling in 61.5%, mismatched relative in 17.6%, matched unrelated donor in 10.2%, and mismatched unrelated donor in 10.7%. Conditioning regimen was myeloablative (50.8%), reduced intensity (23%), or non-myeloablative (22.3%). Patients were followed for a median of 47.8 months (0.3 - 312.9), with 3-year overall survival 91.2% and 3-year event-free survival 85.2%. Median time to death was 9.6 months for 152 patients. Estimated hazard ratio (HR) of death in 7/8 vs. 8/8 HLA matching was 1.5 (95% CI: 0.752, 2.445), which was not statistically significant. However, HR of death for ≤ 6/8 vs. 8/8 HLA matching was 1.7 (95% CI: 1.215, 2.445), indicating a statistically significant increased risk of death. TA-TMA was reported in 27 patients at a median of 2.8 months post-HCT. Univariate analysis of risk factors for TA-TMA indicated increasing incidence with the year of HCT. Age at HCT, HLA matching, and conditioning regimen intensity were not significantly associated. VOD was reported in 24 cases; Cox proportional hazards analysis indicated decreasing incidence with year of HCT. Estimated HR for VOD of patients who developed grade II-IV AGVHD group was 2.965, (95% C.I. 1.089, 8.074). Age at HCT, conditioning intensity, and donor type were not significant. Acute and chronic GVHD were associated with recipient age > 10 years and donors other than HLA-matched siblings; non-myeloablative conditioning was protective against GHVD development. Conclusion Incidence of endothelial complications following HCT for SCD is low, although TA-TMA has been increasingly recognized in recent years. VOD has been observed less frequently over time and correlates with acute GVHD. Donor type, recipient age, and conditioning intensity have the greatest impact on GVHD development.

Allogeneic Hematopoietic Cell Transplantation for Adult Acute Lymphoblastic Leukemia in the Modern Era

Allogeneic hematopoietic cell transplantation (HCT) remains an important treatment for adults with acute lymphoblastic leukemia (ALL). We hypothesized that advances in ALL and transplantation have resulted in improved HCT outcomes in recent years. In this study, we evaluated the characteristics and outcomes of adult ALL patients undergoing allogeneic HCT over the last decade. Patients with ALL aged 18 years and older who underwent allogeneic HCT at Stanford University between 2008 and 2019 were included in this study. Patients were divided into 2 eras based on year of HCT: 2008 to 2013 (earlier era) and 2014 to 2019 (later era). A total of 285 patients were included: 119 patients underwent HCT in the earlier era and 166 in the later era. Patients who underwent transplantation in the later era were more likely to be Hispanic (38% versus 21%) and to have an HCT-comorbidity index ≥3 (31% versus 18%). Donor source for HCT also differed with an increase in the use of HLA-mismatched donor sources (38% versus 24%), notably umbilical cord blood in the later era (16% versus 0%). Patients in the later era were less likely to undergo transplantation with active disease (4% versus 16%); pre-HCT rates of measurable residual disease were similar across the eras (38% versus 40%). In unadjusted analyses, overall survival (OS) improved across eras, with 2-year estimates for the later and earlier eras of 73% (95% confidence interval [CI], 66%-80%) versus 55% (95% CI, 46%-64%), respectively. Multivariable analysis confirmed the association between later era and OS (hazard ratio = 0.52, 95% CI, 0.34-0.78). Finally, among patients relapsing after HCT (25% in later era and 33% in earlier era), the use of novel immunotherapies increased in the later era (44% versus 3%), as did the median OS after post-HCT relapse (16 months versus 8 months, P< .001). OS after HCT for adult ALL has improved in recent years. This is due, in part, to a significant improvement in the ability to effectively salvage adults with ALL relapsing after HCT.

Rare Variant Genetic Association Study for Transplant-Associated Thrombotic Microangiopathy (TA-TMA) Via Whole Exome Sequencing

Introduction: Transplant-associated thrombotic microangiopathy (TA-TMA) is an increasingly recognized hematologic complication after allogeneic hematopoietic cell transplantation (HCT). While few studies have reported germline association with rare variants in complement genes using targeted next generation sequencing (NGS) method, they were limited by small sample size (≤40 TMA cases) and lack of analysis of non-complement genes (PMIDs 26603840, 32131130). In the present study, we employed whole exome sequencing (WES) to assess rare variant contribution to the development of TMA in a hypothesis-driven pathway-specific approach.Methods: In the current case-control genetic association study conducted at Fred Hutchinson Cancer Research Center, we selected 100 patients with a diagnosis of TMA and pre-transplant DNA samples (case definition described previously in PMID 30940363, 33836868). We then performed incidence density sampling to randomly select 100 non-TMA controls after allogeneic HCT matching by age, sex, race, and year of HCT. WES (germline variant detection 40x) was conducted using Illumina NovaSeq. Sequence reads were mapped to hg38 reference genome followed by deduplication and base quality score recalibration. Joint-genotyping was performed to call single nucleotide polymorphism (SNPs) and insertion/deletion (indels) using the GATK v3.3 and Atlas2. Variants were filtered during quality control (QC) and variant quality score recalibration (VQSR) and annotated using ANNOVAR and Ensembl VEP. To optimize signal detection by reducing neutral background variation, we defined qualifying variants as those meeting all 3 criteria: 1) novel or rare variants with a minor allele frequency (MAF) <1% in the reference database gnomAD; 2) functional variants with missense, frameshift, indel, splice region/acceptor/donor, start/stop gained/lost, coding sequence, and protein altering in VEP; and 3) missense variants previously reported to be likely pathogenic from the ClinVar database or predicted to be deleterious from 4/6 in-silico prediction tools (SIFT, Polyphen-2, MutationTaster, MutationAssessor, FATHMM, and FATHMM-MKL) (Figure 1).We then focused on the exome profiles of 5 a priori selected genetic pathways: complement regulation (17 genes), VWF and coagulation (7 genes), VWF clearance (10 genes), ADAMTS13 mimics or interacting proteins (10 genes), and angiopoietin family and endothelial activation (7 genes). Pathway-based and gene-based collapsing association tests were performed using the Optimized Sequence Kernel Association (SKAT-O) test as an optimal test combining burden test and SKAT.Results: After joint variant calling, 91 TMA cases and 93 non-TMA controls passed all QC filters (Table 1). Among 1,485 variants detected in the 5 pathways after QC, 60 variants (73 total mutations) were considered as qualifying variants with MAF <1%, functional coding, and in-silico pathogenic prediction (Figure 1). From pathway-based analysis, a significant association was observed in the VWF clearance pathway (p=0.041) but not in the complement regulation pathway (p=0.308) or the other 3 pathways (Table 2). From gene-based analysis, the significant association in the VWF clearance pathway appeared to be driven by rare variants within the LRP1 gene (Figure 2), which encodes a member of the low-density lipoprotein receptor family of proteins that contributes to the clearance of VWF (PMID 22234691). Sensitivity analyses performed including all rare variants without in-silico pathogenicity prediction resulted in similar findings.Conclusion: Contrary to the initial hypothesis, we did not observe pathogenic germline rare variants in the complement regulation pathway in patients with TA-TMA. Instead, we found a significant association in the VWF clearance pathway, particularly that of the LRP1 gene. In recent years, researchers have shown that VWF can bind to and activate complement proteins. Impaired VWF clearance could lead to the higher predisposition for complement activation observed in patients with TA-TMA. Future functional studies are needed to determine the impact of VWF clearance on the pathogenesis of the disease. [Display omitted] DisclosuresSartain: Alexon Pharamaceuticals: Membership on an entity's Board of Directors or advisory committees. Lee: Incyte: Research Funding; Janssen: Other; Takeda: Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Research Funding; Kadmon: Research Funding; National Marrow Donor Program: Membership on an entity's Board of Directors or advisory committees; Syndax: Research Funding; AstraZeneca: Research Funding; Amgen: Research Funding.

Cytomegalovirus-Specific Immunity Recovers More Slowly after Cord Blood Transplantation Compared with Matched Sibling Donor Allogeneic Transplantation

Rapid quantitative recovery of NK cells but slower recovery of T-cell subsets along with frequent viral infections are reported after umbilical cord blood (UCB) compared with matched sibling donor (MSD) hematopoietic cell transplantation (HCT). However, it remains unclear whether increased propensity for viral infections is also a result of slower recovery of virus-specific immunity after UCB as compared to MSD HCT. We examined the differences in the function of virus-specific peripheral blood mononuclear cells (PBMC) after UCB (N=17) vs. MSD (N=9) using previously collected patient blood samples at various time points after HCT. Interferon-gamma (IFN-γ) enzyme-linked immune absorbent spot (ELISpot) assay was used to quantify the PBMC frequencies that secrete IFN-γ in response to 11 immunopeptides from 5 common viruses. We included the patients who received the same reduced intensity conditioning regimen without ATG, no systemic glucocorticoids and had no relapse or acute/chronic graft-versus-host disease within 1 year after HCT. The CMV-reactive PBMC frequencies were higher in CMV seropositive vs. seronegative patients after HCT. Among CMV seropositive patients, the frequency of CMV-reactive PBMC was lower after UCB compared to MSD throughout one year of HCT. We observed no differences in virus-specific PBMC responses towards HHV6, EBV, BK, and adenovirus antigens between UCB and MSD. Our data demonstrate that the reconstitution of CMV-specific immunity is slower in CMV seropositive recipients of UCB vs. MSD HCT in contrast to other viruses which had similar recoveries. These study findings support implementation of more potent prophylactic strategies for preventing CMV reactivation in CMV seropositive patients receiving UCB HCT.

Chromosomal Aberrations in Pre-HCT Blood Samples and Outcomes after Transplantation in Patients with Myelofibrosis

Introduction: Allogeneic hematopoietic cell transplantation (HCT) is curative for myelofibrosis (MF). However, prognosis post HCT is variable. Identifying subsets of patients who can greatly benefit from HCT is important for clinical decision-making and patient counseling. The Dynamic International Prognostic Scoring System (DIPSS) score includes cytogenetic abnormalities provides important prognostic information. Here, we used high-resolution single nucleotide polymorphism (SNP) arrays to characterize chromosomal aberrations in pre-HCT blood samples from patients with MF and evaluated their added value in patient risk stratification for post HCT survival. Methods: We used the Illumina Global Screening Array to detect somatic copy number alterations (SCNAs) sized ≥2Mb (by calculating the log2 R ratio and B allele frequency and leveraging haplotype information) in pre-HCT blood samples (collected 2-4 weeks prior to HCT conditioning regimen administration) from 923 MF patients who underwent HCT between 2000-2016. Clinical data and blood samples were obtained from the Center for International Blood and Marrow Transplant Research. We used Kaplan-Meier survival analysis and multivariable Cox regression to evaluate the prognostic significance of observed SCNAs on survival after HCT. Results: Median age at HCT was 58 years (range=0.7-76). About 58% were males (N=536), 85% received unrelated donor HCT (N=787), 90% received peripheral blood stem cell grafts (N=826), 47% (N=429) received myeloablative conditioning (MAC), 34% (N=312) received HCT within 1 year from diagnosis, and 537 patients (58%) had known DIPSS score at HCT (47% of them were intermediate II or high). A high frequency of SCNAs were noted in MF (N=623; 67.5%), most commonly on chromosome (chr) 9p (N=224, 24%), chr13q (N=104, 11%), and chr20q (N=102, 11%) (Figure 1). Aberrations noted on chromosomal regions harboring the known MF genes (MPL, DNMT3A, TET2, EZH2, JAK2, SRSF2, CALR, ASXL1, U2AF1) accounted for 28% of all detected (40% of the patients), including JAK2 (9p24.1, N=253, 27%), MPL (1p34.2, N=30, 3.3%) and CALR (19p13.13, N=23, 2.5%). Multivariable models including all MF genes (adjusted for DIPSS score, KPS, year of HCT, hemoglobin count, splenectomy, age, sex, time from diagnosis to HCT, and stratified on CMV match, graft type and conditioning regimen) showed an association between SCNAs on TET2 or SRSF2 regions and poor survival (HR for TET2 =2.40, 95% CI=1.33-4.32, p=0.004; and HR for SRSF2= 2.22, 95% CI=1.26-3.89, p=0.006). TET2 region aberrations were associated with an increased risk of transplant-related mortality (TRM) (HR=2.97, 95% CI=1.53-5.78, p=0.001), worse disease-free survival (DFS; HR=2.22, 95% CI=1.33-3.69, p=0.002), but not the risk of relapse (p=0.12). SRSF2 region aberrations were associated with DFS (HR=1.94, 95% CI=1.11-3.37, p=0.02); no statistically significant association was noted with the risk of relapse (p=0.07) or TRM (p=0.44). These associations were predominant in patients receiving reduced intensity (RIC) or non-myeloablative regimens (Figure 2). Further univariate analyses focusing on all frequently affected chromosomes (affecting ≥10 patients) showed poor OS with SCNAs on chr17p (log-rank p&amp;lt;0.0001), 12p (p&amp;lt;0.0001), 5q (p&amp;lt;0.0001), 13q (&amp;lt;0.001), 8q (p=0.004), 18q (p=0.02) and 4q (p=0.03). In multivariable models stratified on conditioning regimens, chr17p aberrations showed a significant association with excess risk of relapse independent of regimen intensity (HR=5.31, p=0.01 in MAC, and HR=2.70, p=0.02 in RIC). The HR for OS was 2.55, p=0.09, and 2.86, p=0.002, respectively. Other chromosomal aberrations that showed significant associations with inferior OS in patients receiving RIC were SCNAs on chr8q (HR=5.55, p&amp;lt;0.001) (Figure 3), with excess risk of TRM (HR=5.09, p=0.002) but not relapse (p=0.34). In patients that received MAC, elevated risk of mortality was noted with chr5q SCNAs (HR=2.83, p=0.02) with a suggestive association with relapse (HR=2.72, p=0.08) but not with TRM (p=0.59). Conclusion: This study highlights the prognostic ability of pre-HCT detected SCNAs in patients with myelofibrosis, independent on DIPSS score. Relapse risk in patients with aberrations affecting TP53 region was not eliminated by MAC. Follow-up studies to confirm the poor prognosis of those chromosomal changes are warranted. Disclosures Lee: Incyte: Consultancy, Research Funding; Syndax: Research Funding; Kadmon: Research Funding; AstraZeneca: Research Funding; Pfizer: Consultancy, Research Funding; Amgen: Research Funding; Takeda: Research Funding; Novartis: Research Funding.

Expanded Comorbidity Definitions Improve Application of the Hematopoietic Cell Transplantation Comorbidity Index (HCT-CI) for Children and Young Adults with Non-Malignant Diseases Receiving Allogeneic Hematopoietic Cell Transplantation

Expanded Comorbidity Definitions Improve Application of the Hematopoietic Cell Transplantation Comorbidity Index (HCT-CI) for Children and Young Adults with Non-Malignant Diseases Receiving Allogeneic Hematopoietic Cell Transplantation

Expanded Comorbidity Definitions Improve Applicability of the Hematopoietic Stem Cell Transplantation-Comorbidity Index for Children, Adolescents, and Young Adults with Hematologic Malignancies Undergoing Allogeneic Stem Cell Transplantation

Expanded Comorbidity Definitions Improve Applicability of the Hematopoietic Stem Cell Transplantation-Comorbidity Index for Children, Adolescents, and Young Adults with Hematologic Malignancies Undergoing Allogeneic Stem Cell Transplantation

Outcomes of Pediatric Patients with JMML Following Unrelated Donor Transplant: The Impact of Donor KIR Gene Content and KIR Ligand Matching

Introduction Allogeneic hematopoietic cell transplantation (HCT) remains the sole curative therapy for patients with juvenile myelomonocytic leukemia (JMML) leading to a 5-year disease-free survival of ~50%. Whether donor NK cell determinants (e.g., KIR mismatch, KIR A/B genotype) correlate with relapse and survival are unknown. We previously demonstrated that JMML stem cells, defined as Lin-CD34+CD38-, express ligands for NKG2D, NKp30, and NKp44 at levels equal or greater than AML stem cells and that colony-forming units were significantly reduced following incubation of JMML cells with NK cells. Based on these observations we hypothesized that NK cell-dependent mechanisms are a major component of protection from JMML relapse after HCT, and specifically that determinants of greater donor NK cell function (e.g. KIR Bx donors or KIR ligand mismatch) are associated with reduced relapse. We therefore investigated NK cell-related donor and recipient immunogenetics as determinants for outcomes in children transplanted for JMML. Methods: Patients (0 to &amp;lt; 19 years) who received a first allogenic HCT from an alternative donor between 2000 to 2017 and had available donor samples from the Center for International Blood and Marrow Transplant Research (CIBMTR) repository were included in the study. Donor KIR typing was performed on pre-HCT samples and results were correlated with clinical data extracted from the CIBMTR database. The primary endpoint was disease free survival (DFS); secondary endpoints included relapse rate (REL), acute graft versus host disease (aGVHD), chronic graft versus host disease (cGVHD), GVHD relapse free survival (GRFS) and overall survival (OS). Patient and transplant related variables included age (&amp;lt; 2 years vs ≥ 2 years), sex, race, performance score (&amp;lt; 90 vs &amp;gt;90), disease status, graft type (bone marrow, peripheral blood, and cord blood), HLA matching (8/8 vs others), conditioning intensity (myeloablative vs others), use of serotherapy, GVHD prophylaxis (calcineurin inhibitor (CNI)+ methotrexate (Mtx) ± others vs others) and year of HCT (2000-2007 vs 2008-2017). KIR models tested included KIR genotype (AA vs Bx), Donor KIR B content (0-1 vs ≥ 2), centromeric and telomeric region score (AA vs AB vs BB), donor KIR B content score (best, better, neutral), KIR composite score (2 vs 3 vs 4), activating KIR content, presence of activating KIR DS4, ligand-ligand (L-L) mismatch, KIR ligand (KIR-L) mismatch, and missing ligand. Proportional hazards were checked for all covariates in every model. Univariate analysis was performed for primary and secondary outcomes of interest. Covariates with overall p-value &amp;lt; 0.05 and pairwise comparisons with p-value &amp;lt; 0.05 were considered significant. L-L and KIR-L mismatch effects were studied for all outcomes in a subgroup of HLA-mismatched donors (high resolution match &amp;lt;8/8). Results: 165 patients (113 males) with a median follow up of 85 (6-216) months met the study criteria. Of these, 111 received an unrelated donor transplant and 54 received cord blood transplants. This included 77 HLA-mismatched donor transplants. Almost all (161, 98%) received myeloablative conditioning. Half of the study cohort received ATG (91, 55%) and CNI + Mtx based GVHD prophylaxis (81, 49%). Based on donor KIR genotype, 43 patients received grafts from AA donors and 122 from Bx donors. On univariate analysis, there was no difference between AA vs Bx for the primary and secondary outcomes (Table 1). Considering the various KIR models, OS was significantly better for patients without L-L mismatch in the GVHD direction (HR 0.43 (95% CI: 0.20-0.91), p=0.027). Risk of grade II-IV aGVHD was lower in patients with Bx donors (HR 0.59 (CI: 0.35-0.99), p=0.047) and donors with B content score of ≥ 2 (HR 0.51 (0.29-0.89), p=0.017) (Table 2). Conclusion: To our knowledge this is the first study analyzing NK determinants in pediatric JMML HCT recipients. OS and aGVHD were the only outcomes associated with NK cell immunogenetics, but not in expected directions. These unexpected findings may be due to our limited sample size or heterogeneity in graft sources or treatment regimens. Our study identifies a potential benefit of donor of KIR-B genotypes and absence of L-L mismatch in the GVH direction for pediatric JMML patients. These observations require further investigation for confirmation and understanding of mechanism. Disclosures Verneris: Novartis: Membership on an entity's Board of Directors or advisory committees; Fate Therapeutics: Consultancy, Current equity holder in publicly-traded company; Bmogen: Consultancy, Current equity holder in publicly-traded company; Uptodate: Consultancy. Lee:Kiadis Pharma Netherlands B.V: Consultancy, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees, Patents &amp; Royalties.

Delayed CD4+ T-Cell but Faster B-Cell Immune Reconstitution after Ptcy-Based Compared to Conventional Gvhd Prophylaxis after Allogeneic Transplantation

<h3>Background</h3> Post-transplant cyclophosphamide (PTCY) is being increasingly used for graft-versus-host disease (GVHD) prophylaxis after hematopoietic cell transplantation (HCT) across various donor types. However, immune reconstitution after PTCY-based vs. conventional GVHD prophylaxis has not been well studied. <h3>Methods</h3> We evaluated the pace of immune reconstitution (CD4+ T-cell, CD8+ T-cell, NK-cell and B-cell) at 3 months, 6 months and 1 year post-HCT in 583 adult patients receiving myeloablative (n=223) or reduced intensity conditioning (n=360) HCT (2012-2018). Haploidentical (Haplo; n=75) and 8/8 HLA-matched unrelated (MUD, n=508) donor types were included. GVHD prophylaxis was PTCY-based in 75 Haplo and 38 MUD (MUD-PTCY) HCT, while tacrolimus/methotrexate (TAC/MTX) was used in 89 and TAC/Sirolimus (TAC/SIR) in 381 MUD HCT. Clinical outcomes including viral infections, non-relapse mortality (NRM) and overall survival (OS) were compared across all four treatment groups. <h3>Results</h3> The recovery of absolute total CD4+ T-cell count after Haplo-PTCY and MUD-PTCY was significantly lower compared to MUD TAC/MTX or MUD TAC/SIR throughout 1 year of HCT (Figure). In contrast, CD19+ B-cell recovery at 6 months and thereafter was more rapid after Haplo-PTCY and MUD-PTCY HCT in comparison to MUD TAC/MTX and MUD TAC/SIR. In subgroup analysis compared to MUD TAC/MTX HCT, total CD8+ T-cell or NK-cell recovery was not significantly different after Haplo-PTCY or MUD-PTCY HCT. However, patients receiving MUD TAC/SIR vs. MUD TAC/MTX had significantly slower reconstitution of total CD8+ T-cells up to 6 months and CD19+ B-cells at 1 year of HCT, but no significant differences in CD4+ T-cell or NK-cell recovery. The distribution of recipient CMV serostatus was similar in all four groups: 72% in Haplo-PTCY, 62 % in MUD-PTCY HCT, 68% in MUD TAC/MTX and 63% in MUD TAC/SIR (<i>p</i>=0.11). Cumulative incidence of CMV reactivation/infection at 1-year of HCT was higher in patients receiving Haplo-PTCY (39.6%) or MUD TAC-MTX (37.7%) compared to those receiving MUD-PTCY (27.0%) or MUD TAC/SIR (22.8%; <i>p</i><0.01). Whereas the incidence of EBV reactivation/infection was lower in patients receiving PTCY-based GVHD prophylaxis (5.2% in Haplo-PTCY and 8.1% in MUD-PTCY) as compared to patients receiving MUD TAC/MTX (19.7%) or MUD TAC/SIR (20.5%, <i>p</i><0.01). The incidences of HHV6, BK- and other viruses were similar between the groups. Overall, the treatment groups had comparable NRM (<i>p</i>=0.27) and OS outcomes (<i>p</i>=0.78). <h3>Conclusion</h3> Our data demonstrate that the pattern of immune reconstitution after HCT is different after PTCY-based vs. conventional GVHD prophylaxis with delayed total CD4+ T-cell but more rapid B-cell recovery after PTCY-based GVHD prophylaxis. The rates of CMV and EBV viral infections were different across the donor types. However, these differences had no significant influence on NRM or survival after HCT.

Impact of Inherited Chromosomally Integrated HHV-6 on Central Nervous System Dysfunction and Management after Hematopoietic Cell Transplantation

<h3>Background</h3> Human herpesvirus 6B (HHV-6B) is the most frequent infectious cause of central nervous system (CNS) dysfunction after hematopoietic cell transplantation (HCT). HHV-6 species are unique among the herpesviruses for their ability to integrate into telomeric regions of chromosomes. If this occurs in a gametocyte, vertical transmission results in individuals with inherited chromosomally integrated HHV-6 (iciHHV-6) in every nucleated cell. Whether iciHHV-6 in HCT recipients or their donors increases risk for CNS dysfunction is unknown. It is also unknown whether HHV-6 detection, without recognition of iciHHV-6, drives unnecessary interventions. <h3>Objectives</h3> The aims of this study were to compare the incidence of CNS dysfunction and HHV-6-related interventions after HCTs that did and did not involve patients or donors with iciHHV-6. <h3>Methods</h3> We used a previously identified cohort of 87 allogeneic HCT recipients in which the recipient, donor, or both had iciHHV-6 (iciHHV-6^pos). We matched each iciHHV-6^pos HCT with two HCTs in which neither recipient nor donor had iciHHV-6 (iciHHV-6^neg). Matching criteria were age at HCT, year of HCT, myeloablative conditioning, and advanced disease status. Clinical testing for HHV-6 with PCR in plasma or cerebrospinal fluid was symptom based. We compared the cumulative incidence of CNS dysfunction in the first 100 days after iciHHV-6^pos and iciHHV-6^neg HCT. We also compared the proportion of patients in each group who had neuroimaging, lumbar puncture (LP), or HHV-6-targeted antiviral therapy. <h3>Results</h3> There was a similar cumulative incidence of any CNS dysfunction after iciHHV-6^pos and iciHHV-6^neg HCT (<b>Figure 1</b>). None of the subjects in the iciHHV-6^pos group developed CNS dysfunction directly attributable to HHV-6 compared to one subject (0.6%) in the iciHHV-6^neg group diagnosed with HHV-6 encephalitis. HHV-6-targeted antiviral therapy was significantly more frequent after iciHHV-6^pos HCT (OR, 12.7; 95% CI, 1.8-298.3), and two patients developed antiviral associated toxicities that contributed to their cause of death. IciHHV-6^pos recipients also had increased odds of receiving a LP (OR, 1.6; 95% CI, 0.9-2.8) but similar odds of neuroimaging (OR, 1.2; 95% CI, 0.7-2.1). <h3>Conclusions</h3> The cumulative incidence of CNS dysfunction was similar after allogeneic HCT involving recipients or donors with and without iciHHV-6. However, potential misattribution of HHV-6 detection as active infection after iciHHV-6^pos HCT may have resulted in increased healthcare utilization with related adverse events. These findings are likely more pronounced at institutions using routine HHV-6 screening. Reflexive testing for iciHHV-6 may reduce healthcare utilization and improve outcomes after allogeneic HCT.

Association of Donor-Recipient HLA Matching with Outcome of Unrelated Donor Hematopoietic Stem Cell Transplantation: A Study from the Cellular Therapy and Immunobiology Working Party (CTIWP) of the European Society for Blood and Marrow Transplantation (EBMT)

Association of Donor-Recipient HLA Matching with Outcome of Unrelated Donor Hematopoietic Stem Cell Transplantation: A Study from the Cellular Therapy and Immunobiology Working Party (CTIWP) of the European Society for Blood and Marrow Transplantation (EBMT)

Tyrosine Kinase Inhibitors with or without Donor Lymphocyte Infusion Continue to Provide Long-Term Survival after Relapse of Chronic Myeloid Leukemia Following Hematopoietic Cell Transplantation

Treatment for relapse of chronic myeloid leukemia (CML) following hematopoietic cell transplantation (HCT) has expanded to include tyrosine kinase inhibitors (TKI) in addition to the prior standard of care, donor lymphocyte infusions (DLI). In the post-imatinib era of CML, pre-transplant therapy with TKI as well as maintenance with TKI after HCT has become common practice. We hypothesized TKI salvage therapy for relapse after HCT would continue to confer survival advantage compared to patients who received DLI alone, and would enhance therapy when combined with donor lymphocyte infusion. This study was performed through the Center for International Blood and Marrow Transplant Research (CIBMTR) database.Methods: We retrospectively reviewed all patients reported to the CIBMTR registry from 2002-2014 who underwent HCT for CML and then subsequently relapsed post HCT. All the patients had received TKI pre-transplantation. Patients were included if: age was greater than 18 years, underwent first allogeneic transplantation (reduced or myeloablative), received marrow or peripheral blood from sibling/other related or unrelated donor and relapsed following HCT. One month post-relapse was used as a landmark to avoid selection bias due to early death post-relapse. The Cox proportional hazards model was used for multivariate analysis. Variables evaluated in the multivariate analysis included patient-related (age, gender, Karnofsky's performance status (KPS)), disease-related (disease status prior to HCT), and HCT-related (year of HCT, in-vivo T-cell depletion, time from transplant to relapse, conditioning intensity, post HCT TKI maintenance, recipient CMV status, donor type, graft source, GVHD Prophylaxis and pre-relapse GVHD).Results: A total of 215 HCT recipients relapsed and were analyzed in the following groups 1) TKI alone n=128, 2) TKI with DLI n=48, and 3) DLI without TKI n=39 (Table 1). In multivariate analysis, disease status prior to HCT had a significant effect on overall survival (OS). As compared to those in CP1, recipients that went to transplant in blast phase (BP) had a hazard ratio (HR) of 5.5 (95% confidence intervals [CI] 2.92-10.36; p<0.001) and patients in CP2 or higher had a HR 2.65 (95% CI 1.46-4.81; p = 0.001). Patients that received a DLI alone compared to a TKI with DLI had inferior survival HR 2.28 (95% CI 1.23-4.24; p = 0.009). Those who received TKI alone had similar survival compared to those who received TKI with DLI (p=0.81). In a sensitivity multivariate analysis, after controlling for how relapse was detected [clinical/hematologic vs. subclinical [molecular or cytogenetic]), TKI with or without DLI remained significantly associated with superior survival compared to DLI alone (p=0.003). Recipients who did not receive post-HCT maintenance had inferior survival with HR 2.0 (95% CI 1.21-3.31), p = 0.007. The presence of acute GVHD prior to relapse was not significantly associated with post-relapse OS (p= 0.775). Adjusted survival shows OS survival advantage of TKI use, both with or without DLI compared to DLI alone (p=0.013) (Fig 1).Conclusion: Our study showed that disease status prior to HCT continues to confer poor prognosis. Interestingly, the presence of GVHD prior to relapse shows no impact on survival in this population of patients that had relapsed following HCT. Additionally, maintenance TKI post-HCT was associated with superior post-relapse survival and this was independent of time from HCT to relapse. Post relapse overall survival was highest in HCT recipients who received a salvage TKI containing regimen compared to DLI only salvage therapy. This data supports that despite use of TKI pre-transplantation and in maintenance therapy, TKI salvage therapy continues to provide significant survival following relapse in patients with CML following HCT. This data does not suggest that adding a DLI to TKI adds an improvement in OS, although the sample size is small. DisclosuresNo relevant conflicts of interest to declare.

1559. Hematopoietic Cell Transplantation with Post-transplant Cyclophosphamide: Impact of Donor Type on Pre-engraftment Blood-Stream Infections

BackgroundThe aim of the study was to estimate the cumulative incidence of pre-engraftment blood stream infections (PE-BSI), its predictive factors and the infection-related mortality (IRM) after hematopoietic cell transplantation (HCT) from any donor type, with post-transplant cyclophosphamide (PT-Cy).MethodsRetrospective cohort study on 235 adults who underwent peripheral blood HCT from every donor type with PT-Cy platform, from 2013 to 2017 at San Raffaele Scientific Institute. The Poisson regression was used to estimate the crude incidence rate (IR) of PE-BSI. The Fine-Gray competing risk model was applied to estimate the cumulative incidence function (CIF) of the first PE-BSI and its predictive factors and of IRM.ResultsPatients’ characteristics are reported in Table 1. During 5,316 person-days of follow-up (PDFU), 77 PE-BSI episodes occurred in 72 patients: IR = 1.45 per 100-PDFU [95% confidence interval (95% CI) 1.13–1.77]. The median time to PE-BSI was 13 days (IQR: 7–17) and the estimated CIF at 28 days was 32% (95% CI: 26–39%); no differences in CIF according to donor type [30% vs. 34% vs. 32% in match-related, match-unrelated and haploidentical donor, respectively; Gray’s test: P = 0.968]. Among the 87 isolated pathogens, 60% were Gram-positive bacteria (GPB), 39% Gram-negative bacteria (GNB) and 1% nontuberculous mycobacteria. CIFs of GNB and GPB PE-BSI by type of donor are shown in Figure 1. By multivariate analysis (Table 2), after adjustment for age, sex, year of HCT, donor type and disease phase at HCT, the CIF of any PE-BSI was higher in subjects with absolute neutrophils count ≤500 for ≥7 days before HCT [adjusted hazard ratio (AHR) = 2.90] and in multi-drug resistant (MDR) GNB rectal carriers before HCT [AHR = 2.68]. These covariates were confirmed as independent factors also for GNB PE-BSI. Overall, IRM at 30 days was 5% (95% CI: 2–8%) with no differences by donor type (Gray’s test: P = 0.106).ConclusionHCT with PT-Cy platform showed a 32% of cumulative incidence of PE-BSI at 28 days and donor type did not affect its occurrence, which was conversely increased by prolonged and severe neutropenia and MDR GNB rectal carriage before HCT. Haploidentical setting did not retain a higher IRM at 30 days than match-related and match-unrelated donors. Disclosures All authors: No reported disclosures.

Surgical lung biopsy in children after hematopoietic cell transplantation

Background/PurposePulmonary complications are some of the leading causes of morbidity and mortality in immunocompromised pediatric patients. We sought to assess the value of surgical lung biopsy (SLB) in hematopoietic cell transplantation (HCT) pediatric patients. MethodsA retrospective review of patients who underwent SLB within one year of HCT between 1999 and 2015 was performed. ResultsTwenty-nine patients (15 females, 14 males) with a median age of 10years (range, 0.6–23) were identified. Median interval between HCT and SLB was 114.8days (range, 16–302). At surgery, 11 (38%) patients were intubated, and 7 (24%) were receiving supplemental oxygen. The most common histological finding was cryptogenic organizing pneumonia in 8 cases (27%), followed by infection in 7 (24%). Perioperative complications (17%) included bronchopleural fistula (n=2), splenic laceration from a trocar injury (n=2), and hemothorax (n=1). Changes in therapy occurred in 25 patients (86%). Twenty-four (83%) patients survived more than 30days post SLB, and the overall survival rate was 41% with a median follow-up of 8.5years (range, 1–13). ConclusionSLB appears to be safe and informative in pediatric patients after HCT and led to changes in therapy in most patients. However, long-term survival after this procedure was <50%, reinforcing the fact that pulmonary complications are some of the leading causes of mortality in these patients. Type of StudyRetrospective analysis. Level of EvidenceLevel IV.