Background ACCESS (NCT04904588), a multi-center phase II trial, was designed to assess safety and efficacy of HLA-mismatched unrelated donor (MMUD) peripheral blood allografts in adult patients with high-risk hematologic malignancies receiving myeloablative (MAC) or non-myeloablative/reduced-intensity conditioning (NMA/RIC) and standard-dose post-transplantation cyclophosphamide (SD PTCy) as graft-versus-host disease (GvHD) prophylaxis. One-year overall survival (75%) was similar irrespective of conditioning intensity and degree of donor HLA MM (Al Malki et al., JCO 2025). However, 56% MAC and 64% RIC adult recipients experienced at least one Common Terminology Criteria for Adverse Events (CTCAE) grade (Gr) ≥2 infection within the first 100 days of transplant (D100). Herein, we describe infection burden in ACCESS patients within one year after transplant. Methods CTCAE Gr≥2 infections were analyzed by time after transplant (Days 0-30, 31-100, 101-180, 181-365), conditioning intensity, degree of donor HLA MM (HLA 7/8 vs. <7/8), pathogen type, and post-MMUD HCT outcomes (Gr2-4 acute GvHD, moderate/severe chronic GvHD, and American Society for Transplantation and Cellular Therapy (ASTCT) Gr≥2 cytokine release syndrome. Infection density was calculated as number of infections per 100 days at risk for enrolled patients. Infection data were summarized with standard descriptive statistics. Infection density with 95% confidence intervals (CI) were estimated using Poisson regression models; p<0.05 was considered statistically significant. Results Median (range) ages for 268 patients receiving MAC (n=75) and RIC/NMA (n=193) were 49.8 (20.4-65.6) and 64.4 (24.3-77.9) years, respectively. CTCAE Gr≥2 infections occurred in 183 (69%) patients: 49 (65%) MAC and 134 (69%) RIC/NMA recipients. Days 0-30 infection densities for Gr2-5 and Gr3-5 infections were higher relative to infection densities at other post-transplant periods and irrespective of conditioning intensity (Fig. 1A) and degree of donor HLA MM (Fig. 1B). When comparing infection densities by conditioning intensity, patients receiving RIC/NMA had higher infection densities at Days 31-180 for Gr3-5 infections (Fig. 1A). When comparing infection densities by degree of donor HLA MM, significant differences were noted only at Days 181-365 in the RIC stratum (Fig. 1B). Similar distribution of pathogen types by conditioning intensity were noted early (Fig. 1C) and late (Fig. 1D) post-transplant, with predominantly gram-positive bacteria and non-respiratory viruses, respectively. Finally, pathogen type frequencies by clinical outcomes were indistinct (Fig. 1E). Conclusion In the MMUD PBSC transplant setting, SD PTCy associates with significant infection burden. These findings provide insights into potential interventions to prevent infection or augment immune response after MMUD transplant.

Calcineurin inhibitor (CNI)-free regimens with post-transplant cyclophosphamide (PTCy) for graft-versus-host disease (GVHD) prophylaxis are gaining interest to reduce CNI-related toxicities. While small studies with sirolimus (Siro) are promising, large-scale comparative data are lacking. We compared PTCy+CNI (n=7839, reference) vs. PTCy+Siro (n=637) as GVHD-prophylaxis in hematopoietic cell transplantation (HCT) using the Center for International Blood and Marrow Transplant Research database.We analyzed adults undergoing first HCT for AML, ALL, or MDS (2017-2022). Donor types included matched sibling (MSD, 754), 8/8-HLA matched unrelated (MUD, 2222), 7/8-HLA mismatched unrelated (MMUD, 890), or haploidentical (haplo, 4607). Multivariable Cox models, adjusted for center effects, compared cause-specific hazards, and a significance level of 0.01 was used.Median age at HCT was 59 vs. 63 (12% vs 22% ≥70) years in the CNI and Siro groups, respectively. More patients in the Siro group had MMUD and received a non-myeloablative regimen. Baseline renal function was similar, though GFR is not available for most patients. 90% in both groups received MMF. Significant interactions between treatment groups and donor type were observed for disease free survival (DFS), relapse, grade II-IV acute GVHD, and neutrophil engraftment.In the multivariable Cox models, the PTCy+Siro regimen was associated with inferior overall survival (OS) compared to PTCy+CNI [Hazard ratio (HR) 1.22, 95% confidence interval (CI) 1.11-1.34; p<.0001]. OS benefit with PTCy+CNI was strongest in haplo (HR 1.30, [1.14-1.48]; p=0.0001) and MMUD (HR 1.59, [1.12-2.26]; p=0.0094), but not significant in MSD and MUD. Lower OS with PTCy+Siro was primarily due to higher treatment-related mortality (TRM: HR 1.44, [1.16-1.78]; p=0.0008). The overall DFS and relapse risk did not differ between the regimens. The PTCy+Siro group had a significantly higher risk of grade III-IV acute GVHD (HR 1.36, [1.08-1.72]; p=0.0105), with no differences in the risk of grade II-IV acute GVHD and systemic therapy-requiring chronic GVHD. PTCy+Siro may be associated with inferior GVHD-free, relapse-free survival, although this difference did not meet the predefined threshold for statistical significance (GRFS: HR 1.13, [1.02-1.25]; p=0.0205). Engraftment was slower with PTCy+Siro for neutrophils (HR 0.75, [0.68-0.83]; p<.0001) and platelets (HR 0.71, [0.64-0.79]; p<.0001). Infection was the primary cause of death in 15.7% of patients in the CNI group versus 21.2% in the Siro group.The superiority of a PTCy+CNI regimen is multi-faceted. While PTCy+CNI was associated with reduced grade III-IV acute GVHD and lower TRM, the overall survival benefit was most pronounced in the settings of haplo and MMUD HCT. Future analyses will include additional toxicity evaluations.

Background Access to allogeneic hematopoietic cell transplantation (HCT) remains limited for patients of non-European ancestry due to donor unavailability. While 7/8 mismatched unrelated donors (MMUD) provide acceptable outcomes, HCT with ≥2 allele mismatches (<7/8) have historically yielded poor survival and prohibitive toxicity. Post-transplant cyclophosphamide (PTCy) has significantly improved outcomes after MMUD HCT, but the prognostic effect of increasing HLA disparity in this setting is unclear. Methods The prospective ACCESS trial (NCT04904588) evaluated PTCy-based GVHD prophylaxis in adults receiving 4–7/8 HLA-mismatched peripheral blood stem cells (PBSC) from donors ≤35 years old after myeloablative (MAC) or reduced-intensity/non-myeloablative (RIC/NMA) conditioning. Primary endpoint was 1-year overall survival (OS). Secondary endpoints included graft failure, non-relapse mortality (NRM), relapse, acute and chronic GVHD, and GVHD-free relapse-free survival (GRFS). Results Among 268 adults, 85 received <7/8 and 183 received 7/8 MMUD PBSC grafts. The <7/8 cohort (median age 57, range 24–78; 49% male) was racially diverse, with the majority (61%) identifying as racial/ethnic groups other than non-Hispanic White, and included 6/8 (82%), 5/8 (14%), and 4/8 (4%) matches. Conditioning intensity in this group was MAC (n=23) and RIC/NMA (n=62). Diagnoses included AML (55%), MDS (15%), lymphoma (14%) and ALL (11%). Most received fludarabine/melphalan (44%) or myeloablative busulfan/fludarabine (21%); the median CD34+ cell dose was 5.5 × 10^6/kg, and 75% of grafts were cryopreserved. The 7/8 group (median age 63, range 20–79; 52% male) had similar disease distribution, conditioning intensity [MAC (n=52), RIC/NMA (n=131)], and infused cell dose. In this cohort, 61% of grafts were cryopreserved, and nearly half (45%) identified as racial/ethnic groups other than non-Hispanic White.At 1 year, OS was 86% (95% CI, 76–92) for <7/8 vs 79% (72–84) for 7/8. Relapse was 23% (14–33) vs 17% (12–23); NRM 8% (4–16) vs 14% (9–19); and GRFS 55% (43–65) vs 51% (44–58) in <7/8 and 7/8, respectively. At 6 months, grade II–IV acute GVHD occurred in 34% (24–44) vs 39% (32–46), and grade III–IV in 7% (3–14) vs 8% (5–13) in <7/8 and 7/8, respectively. At 1 year, moderate/severe chronic GVHD was 8% (3–15) vs 11% (7–16). Primary graft failure occurred only after RIC/NMA: 8% (3–18) with <7/8 vs 3% (1–8) with 7/8.In <7/8 recipients, 1-year OS was 91% with MAC and 84% with RIC/NMA; relapse 32% vs 20%; GRFS 53% vs 55%; and NRM 9% vs 8%, respectively. Conclusions PTCy-based GVHD prophylaxis results in excellent outcomes following <7/8 MMUD HCT, with OS >80% and low NRM and GVHD, comparable to 7/8. Extending donor criteria to 4–6/8 mismatches should broaden equitable donor access while permitting optimization of non-HLA factors.

Human leukocyte antigen (HLA)-mismatched unrelated donor (MMUD) hematopoietic cell transplantation (HCT) has emerged as an effective therapy for adult patients with hematologic malignancies. The MMUD ACCESS Trial (NCT04904588), which incorporated post-transplant cyclophosphamide (PTCy) as graft-versus-host disease (GvHD) prophylaxis, demonstrated combined overall survival of 81% in enrolled patients, 59% who were ethnically diverse. Given PTCy is also associated with significant bacterial and viral infections, we defined infection burden in the full adult cohort (N=268) using infections graded according to an international standard (CTCAE, Common Terminology Criteria for Adverse Events, version 5.0). Infection density (number of infections per 100 days at risk), cumulative incidence of infection, and frequency of pathogen types were categorized by post-HCT time, conditioning intensity, level of donor HLA mismatch, and presence of acute GvHD. Of 465 recorded CTCAE grade 2-5 infections recorded in 183 (68%) adults, 176 (38%) infections were significant or life-threatening and most infections (296, 64%) occurred within the first 100 days. Infection density at Days 0-30 was significantly higher than at other times and was similar by conditioning and level of HLA mismatch as were pathogen types and isolates. Multivariable analysis showed that acute GvHD is significantly associated with infection. Lastly, 21 (7.8%) patients died from infection. Results show significant infection burden using standard dose PTCy in the MMUD HCT setting, irrespective of conditioning and level of donor HLA mismatch, and will serve as a benchmark for trials investigating reducing infection burden following MMUD HCT.

Introduction The evidence base informing donor selection is rapidly evolving, with updated guidelines from NMDP/CIBMTR for allogeneic hematopoietic cell donor selection published in the past year. A major change is the shift away from a strictly linear search process toward a parallel, patient-specific approach based on the findings of BMT CTN 1702, requiring many centers to adjust existing practices. Translating these recommendations into practice is often hindered by complex workflows, competing demands, and variability across centers. Traditional dissemination (e.g., publication) may raise awareness but rarely ensures uptake in routine practice. We applied dissemination and implementation science principles to operationalize recommendations, focusing on workflows, decision support, and tailored, multi-channel dissemination to promote adoption. Methods We conducted stakeholder mapping and role-based needs assessments to identify audiences most engaged with the updated guidelines. Workflow and process mapping of donor selection practices informed the design of supplementary dissemination and implementation materials. Developed in partnership with guideline authors, these clarified continuity with prior practices, identified what is new or different, and highlighted grey zones of evidence and program-level decision points. Multimodal strategies were then employed to promote awareness, accessibility, and usability. Results We created a suite of resources to support implementation of the updated guidelines, including a practice flowchart and decision tree (Figure 1), comparative tables, and a rapid-reference webpage. A Spanish-language version was added to increase reach. Dissemination efforts leveraged social media, podcasts, newsletters, emails, and national conference presentations tailored to diverse stakeholders. To facilitate implementation, we provided expert-led sessions with centers, developed internal toolkits, and updated existing educational programs. Conclusion Guidelines are only impactful if they can be translated into practice, which requires support beyond publication. By developing complementary resources and deploying multimodal dissemination strategies, we aim to enable consistent adoption of evidence-based donor selection practices. This work provides a scalable model for translating rapidly evolving evidence into practice. Ongoing efforts will assess the effectiveness of the materials and the adoption of the donor selection guidelines.

PURPOSE:Hematopoietic cell transplantation (HCT) is considered the only curative treatment for patients with myelodysplastic syndrome (MDS), with disease relapse (REL) as the major cause of post-HCT failure. We aimed to conduct a comprehensive genomic screening of prognostic biomarkers associated with post-HCT disease relapse. METHODS:In this retrospective, cohort study, we analyzed whole-genome sequencing data from 494 non-Hispanic White patients with MDS who received HCT in the Center for International Blood and Marrow Transplant Research network. Genomic prognostic biomarkers were determined by cause-specific Cox regression multivariable models, with additional sensitivity analyses on unrelated transplant subcohorts and different competing outcomes. Their clinical significance on post-HCT risk stratifications was further evaluated via random survival forest models with optimism-bias adjusted bootstrap procedure. RESULTS:Ten novel genomic biomarkers associated with relapse were identified, including somatic mutations in two genes (HNRNPA3 and TENM2), one locus (HSPC324) with a burden of rare germline single-nucleotide variants (SNVs), six loci harboring common SNVs, and one region harboring a structural variant (SV). For prognostic performance comparisons, the combined model that included these novel genomic biomarkers showed significant improvement of concordance indices (0.747 [95% CI, 0.705 to 0.786]) for predicting post-HCT disease relapse, compared with 0.547 (95% CI, 0.503 to 0.595) in the baseline model (Revised International Prognostic Scoring System [IPSS-R] + hypomethylating agents + graft-versus-host disease prophylaxis). Especially, the combined model showed superior risk stratifications for low or intermediate IPSS-R MDS patients with divergent post-HCT outcomes. CONCLUSION:Our results suggest that SNVs and SVs beyond recurrent somatic mutations and cytogenetic abnormalities may play important roles in determining post-HCT relapse risk stratification in patients with MDS.

ABSTRACT:Posttransplant cyclophosphamide (PTCy)-based graft-versus-host disease (GVHD) prophylaxis is now standard for matched unrelated donor (MUD) hematopoietic cell transplantation (HCT). Previous studies comparing MUD and haploidentical donor HCT using PTCy were limited in size and follow-up. We therefore performed a registry-based analysis examining the impact of donor type on HCT with PTCy. Adult patients (n = 5873) receiving MUD (n = 1973) or haploidentical (n = 3900) HCT with PTCy for acute leukemia (74.2%) or myelodysplastic syndrome (MDS; 25.8%) reported to the Center for International Blood and Marrow Transplant Research between 2017 and 2021 were included. Primary end points were 3-year overall survival (OS) and GVHD-free, relapse-free survival (GRFS). Cox regression and sensitivity analyses were performed through adjustment of propensity scores. Haploidentical HCT had worse OS (hazard ratio [HR], 1.15; 95% confidence interval [CI], 1.04-1.27; P = .005) and GRFS (HR, 1.19; 95% CI, 1.10-1.29; P < .001) versus MUD HCT. Donor age was the only other donor factor associated with survival. Results were confirmed in sensitivity analysis. When restricted to reduced intensity conditioning or donors <30 years, OS did not differ between groups. Haploidentical HCT was associated with higher primary graft failure (HR, 1.67; P = .002), increased grade 3/4 acute GVHD (HR, 1.28; P = .039), higher moderate/severe chronic GVHD (HR, 1.47; P < .001), and nonrelapse mortality (HR, 1.34; P < .001). Grade 2 to 4 acute GVHD and relapse risk did not differ. This large analysis showed that in adults with acute leukemia or MDS, MUD HCT was associated with improved outcomes versus haploidentical HCT with PTCy-based GVHD prophylaxis.

Advances in graft-versus-host disease (GVHD) prevention and treatment have resulted in expanded donor options and improvement in treatment-related mortality (TRM). This analysis aimed to compare the incidence of acute and chronic GVHD (aGVHD and cGVHD) in pediatric patients by recipient age and to evaluate the impact of GVHD on overall survival (OS) and TRM. We included 14,099 patients ≤21 years who received their first allogeneic hematopoietic cell transplantation from 2002-2020, categorizing recipient age as: 0-2y (infants/toddlers), 3-12y (school-aged), and 13-21y (adolescent/young adult). There was no difference in grade II-IV and III-IV aGVHD by Day 100 among age groups, except in patients with nonmalignant disease, where there was a small increase in incidence of severe aGVHD in older patients. Incidence of moderate/severe cGVHD by 1y was higher with age. A similar impact of age was observed after adjusting for patient, donor and transplant characteristics. Risk of severe aGVHD was higher in older children with NMD. Severe aGVHD and moderate/severe cGVHD were independently associated with inferior OS. In patients with malignant disease, both severe aGVHD and moderate/severe cGVHD were associated with increased risk of TRM. In conclusion, risk of moderate/severe cGVHD increases with recipient age, and risk of severe aGVHD is increased among older patients with nonmalignant conditions. Despite the low overall incidence of aGVHD and cGVHD in children, both are associated with significantly worse survival. These data highlight the need to consider GVHD outcomes at time of consultation and for improved prevention and treatment approaches.

ABSTRACT:Acute graft-versus-host disease (aGVHD) contributes to significant morbidity after allogeneic hematopoietic cell transplantation (allo-HCT). We aimed to develop and validate a clinical score to identify patients with significantly different risk for developing aGVHD. Analysis included adults who underwent allo-HCT during 2008-2019. Eligibility criteria were widely inclusive of transplant indications, donor types, graft types, conditioning regimens, and GVHD prophylaxis regimens. The final cohort of 21 796 patients was randomly split into training and validation cohorts, with 15 258 (70%) and 6538 (30%) patients, respectively. The primary outcome was grade 2 to 4 aGVHD, and the secondary outcome was grade 3 to 4 aGVHD, by day 100 posttransplant. Risk scores were developed using the training cohort, tested using the validation cohort, and stratified into 4 percentile groups. The odds of grade 2 to 4 aGVHD by day 100 posttransplant were 1.50 (95% confidence interval [CI], 1.29-1.75; P< .0001) for the 25th to 50th percentile group, 2.0 (95% CI, 1.78-2.40; P< .0001) for the 50th to 75th percentile group, and 3.1 (95% CI, 2.72-3.65; P< .0001) for the >75th percentile group compared with the ≤25th percentile group in the validation cohort. The odds of grade 3 to 4 aGVHD by day 100 posttransplant were 1.4 (95% CI, 1.11-1.74; P = .0043) in the 25th to 50th percentile group, 2.0 (95% CI, 1.61-2.49; P< .0001) in the 50th to 75th percentile group, and 3.2 (95% CI, 2.64-3.98; P< .0001) in the >75th percentile group compared with the ≤25th percentile group in the validation cohort. Here, to our knowledge, we have developed the first validated, widely inclusive clinical risk score for the development of aGVHD after allo-HCT.

Introduction HLA alloimmunization occurs through exposure to non-self HLA antigens from allogeneic blood products or pregnancy. The resulting anti-HLA antibodies (HLA-Abs), when directed at donor-specific HLA antigens (DSA), are a prognostic biomarker for hematopoietic cell transplantation (HCT) engraftment failure and mortality, necessitating either selection of an alternate donor or immunodepletion of the existing DSA. We sought to understand how pre-sensitization to HLA impacts volunteer unrelated donor (URD) availability on the NMDP registry. Methods The cohort included 1,197 consecutive patients referred for HCT evaluation at Memorial Sloan Kettering Cancer Center between 2021-2024. All subjects underwent HLA-A, -B, -C, -DRB1, -DRB3/4/5, -DQA1/B1 and -DPA1/B1 genotyping and HLA-Abs evaluation using commercially available solid-phase immunoassays. The effects of HLA-Abs on donor availability was determined by performing URD searches before and after exclusion of donors with DSA, considering mean fluorescence intensity (MFI) cut points (1000, 4000 and 10000). URDs considered were 5-8/8 matched age 18-30 and adjusted for donor availability at confirmatory typing. Results Median patient age was 63 (interquartile range: 49-70) and 511 (42.4%) were female. Self-reported race/ancestry was non-Hispanic White (NHW) in 710 (59.3%), Black/African-American (AFA) in 134 (11.2%), Latino/Hispanic (HIS) in 121 (10.1%), Asian/Pacific-Islander (API) in 102 (8.5%) and mixed/unknown (UNK, n = 130, 10.9%) patients. The most common diseases were AML (n = 379, 31.7%), MDS (n = 354, 29.6%), and NHL (n = 191, 16.0%). HLA-Abs with MFI >1,000 were detected in 445 (37.2%) of patients. HLA-Abs frequency did not differ significantly between NHW and other groups (38.9% vs. 34.5%, P = 0.12); however, HLA-Abs were much more frequent in female compared to male patients (49.7% vs. 26.8%, P <0.0001). High titer (MFI >10,000) HLA-Abs were found in 14.8% of patients and were also much more frequent in females compared to males (26.4% vs. 5.7%, P <0.0001).Among females the rate of no donor availability was 1% without considering HLA-Abs and 2% and 4% when considering HLA-Abs at the 10,000 and 4,000 MFI level, respectively (figure). Further, 18.5% of females with HLA-Abs would be forced to select a lower matched donor to avoid DSA and 4.3% lose available HLA-8/8 matched donors due to antibodies against HLA-DRB3/4/5, DQ or -DP. Examining female patients with HLA-Abs with MFI >10,000 (N=135), the rate of no donor availability was 7.4% and 11.1% would require selection of an HLA lesser matched donor. Conclusions Consideration of HLA mismatched URDs provides access to suitable donors, particularly in patients of racial or ethnic minority ancestry. Here, we demonstrate that among adult female patients, HLA-Abs are common and, in patients of minority ancestry, have a significant impact on donor availability.

BMT CTN 1703 showed post-transplant cyclophosphamide (PTCy) significantly improves GVHD-free, relapse-free survival (GRFS) compared to standard tacrolimus and methotrexate (MTX) prophylaxis in HLA-matched RIC HCT, with similar relapse, overall and disease-free survival (OS, DFS), and treatment-related mortality (TRM). We hypothesized PTCy would also be associated with improved GRFS compared with antithymocyte globulin (ATG)-containing regimens and conducted a CIBMTR study comparing PTCy versus CNI/MTX ± ATG in a real-world setting.The primary endpoint was 2-year GRFS; secondary endpoints: acute GVHD, chronic GVHD requiring immunosuppression (cGVHD), relapse, TRM, DFS, and OS. Adults ≥18 years with AML, ALL (CR1/CR2), or MDS undergoing first RIC HCT from an HLA-matched related or unrelated donor from 2014–2022 using PBSC grafts were included. Multivariable Cox models, adjusted for center effects, compared cause-specific hazards across GVHD prophylaxis groups (α=0.01).The study included 3 cohorts: PTCY-based (n=1236, reference), CNI/MTX with ATG (n=1015) and CNI/MTX (n=3699). Median age at HCT was 65 years, similar in all groups. 71% had MUD donor, 25% had HCT-CI ≥5, and 20% were ≥70 years. AML was the leading diagnosis (53%). 84% of PTCy-based HCTs were from 2019-2022. More grafts were cryopreserved in the PTCy cohort (50% vs 27%).At 2 years, GRFS was significantly higher in PTCy (35.4%), compared to CNI/MTX/ATG (23.2%), and CNI/MTX (17.8%, p<0.001). In multivariable regression analysis, compared to PTCy, patients (pts) receiving CNI/MTX/ATG prophylaxis had inferior GRFS after 6 months [HR 1.30 (1.09-1.55, p=0.0034)], higher aGVHD II-IV [HR 1.47 (1.14-1.89), p=0.0032], higher cGVHD after 6 months [HR 1.68 (1.32-2.14), p<0.0001] and higher TRM after 10 months [HR 1.65 (1.13-2.40), p=0.009]. Similar to BMT CTN 1703 results, pts receiving CNI/MTX had lower GRFS after 6 months [HR 1.74 (1.51-2.00), p<0.0001], higher aGVHD II-IV [HR 1.36 (1.11-1.67), p=0.0031] and III-IV [HR 1.75 (1.31-2.34), p=0.0002], higher cGVHD after 6 months [HR 3.23 (2.62-3.97), p<0.0001], higher TRM after 10 months [HR 2.19 (1.53-3.13), p<0.0001], but also lower relapse risk after 4 months [HR 0.65 (0.55-0.77), p<0.0001]. In CNI/MTX groups, omission of ATG was associated with lower relapse [HR 0.72 (0.61–0.86), p=0.0003]. OS and DFS did not differ between cohorts. The association of PTCy with higher GRFS was consistent in subgroup analyses restricted to MUD, MSD, age ≥70 and sensitivity analyses of HCT between 2019-2022 (Table).This large registry study of adults undergoing RIC HLA-matched HCT, PTCy-based GVHD prophylaxis was associated with superior GRFS compared to CNI/MTX with and without ATG, supporting PTCy-based GVHD prophylaxis use in RIC HCT for adults with leukemia in remission, or MDS. There was no difference in OS and DFS. Analysis is underway to identify patients at higher relapse risk.

Background The prognostic impact of the molecular genetic landscape of myelofibrosis (MF) on hematopoietic cell transplantation (HCT) outcomes remains unclear. This study evaluates gene-specific associations with HCT outcomes in MF patients, overall and by driver mutation status. Methods We performed deep sequencing (mean depth 664x) of 95 myeloid genes in DNA from pre-HCT blood samples of 930 patients with primary or secondary MF who underwent HCT between 2000 and 2016, with clinical data and pre-HCT blood samples available at CIBMTR®. Somatic variants were called using Mutect2 and germline variants were filtered out using a panel of normals constructed from 989 age- and sex-matched controls, and the Pan-Cancer Analysis of Whole Genomes (PCAWG). Only pathogenic/likely pathogenic (PLP) variants, defined according to the American College of Medical Genetics and Genomics/Association for Molecular Pathology (ACMG/AMP) criteria, were included. Cox proportional hazards models were used to assess overall survival (OS) with final models adjusted for patient age and sex, DIPSS, donor-recipient CMV match, donor type, and year of transplant. Genes detected in ≥5% of patients (N ≥47) were included in OS analysis. Results Driver mutations were detected in 81.7% of the patients, with JAK2 the most common (57.3%) followed by CALR (19.6%), and MPL (6%), leaving 170 patients (18.3%) triple-negative (TN). Other common mutations included ASXL1 (312, 33.5%), U2AF1 (133, 14.3%), TET2 (132, 14.2%), SRSF2 (116, 12.5%), and TP53 (78, 8.4%) (Figure 1). Compared to JAK2+ patients, TN patients had inferior OS (HR=1.54; p<0.001), while no significant OS differences were observed for CALR+ (HR=0.81; p=0.11) or MPL+ (HR=0.70; p=0.13) patients (Figure 2A). Mutations in high molecular risk (HMR) genes combined (ASXL1, EZH2, IDH1/2, SRSF2, U2AF1, CBL, KRAS, NRAS) were not associated with survival (HR=0.90; p=0.30; Figure 2B). PLP variants in TP53 were linked to inferior OS across patients (HR=2.68; p<0.001; Figure 2C), increasing relapse/disease progression risk in CALR+ (HR=2.70; p=0.03) and possibly TN (HR=2.00; p=0.14), and transplant-related mortality (TRM) risk in JAK2+ patients (HR=1.89; p=0.008). In TN patients, the adverse prognosis was primarily driven by TET2 mutations (HR=2.16; p=0.007), specifically associated with relapse (HR = 2.22; p = 0.02). ASXL1 mutations increased post-HCT mortality only in MPL+ patients (HR = 3.78; p = 0.01), mainly due to excess TRM (HR = 4.84; p = 0.05). Conclusions TP53 mutations are strong predictors of poor outcomes across MF patients, whereas TET2 and ASXL1 mutations confer prognostic value only in TN and MPL+ patients respectively. The absence of association between HMR mutations and outcomes suggests that HCT mitigates the negative effects of HMR genes. These findings support pre-HCT genetic testing in MF to refine risk stratification and management strategies.

Telomere length (TL) is associated with health outcomes. Southern Blotting (SB) is the gold standard of TL measurements, while qPCR-based TL measurements are the most used because of their high throughput. We compared leukocyte TL (LTL) measurements by SB and qPCR, and their ability to capture LTL associations with demographic factors. This study included 908 healthy donors for hematopoietic cell transplantation who had blood samples and data available at CIBMTR®. We used quantile regression (QR) to assess the associations between selected demographic factors and LTL across the LTL distribution. Pearson correlation coefficient and Bland–Altman plot were used to compare SB-LTL and qPCR-LTL measurements. SB-LTL and qPCR-LTL were modestly correlated (r = 0.58, P < 0.001). On average, SB-LTL shortened by 29 base pairs (bp) per year and was 190 bp longer in females than in males. QR analyses showed that the association between SB-LTL and age varied across the LTL distribution, with stronger age-related shortening at higher percentiles (25 bp at the 25th percentile vs. 31 bp at the 75th percentile; P = 0.003). Females had longer SB-LTL than males across all percentiles (P < 0.05 in SB-LTL analysis), and the magnitude of this sex difference did not vary significantly across the LTL distribution (157 bp at the 25th percentile vs. 221 bp at the 75th percentile; P = 0.33). Both SB and qPCR showed an inverse relationship between LTL and age, though the magnitudes differed between methods. Considering the full LTL distribution in studies of lifestyle factors and diseases may provide better molecular insights and guide LTL utilization in health applications.

Background Mitochondria are critical for stem cell homeostasis, heme biosynthesis, iron utilization, and immune responses. We previously showed that patient mitochondrial DNA (mtDNA) variants in genes such as MT-CYB and MT-ND5 predict post-transplant outcomes in myelodysplastic syndromes (MDS). In this study, we investigated whether similar associations exist in myelofibrosis (MF) and sought to identify MF-specific prognostic mtDNA variants. Methods We performed ultra-deep mtDNA sequencing (500 ×) on pre-transplant whole-blood samples from 228 MF patients who underwent allogeneic hematopoietic cell transplantation (HCT) reported to the Center for International Blood and Marrow Transplant Research (CIBMTR) between 2000 and 2016. Mitochondrial genome sequences were aligned to the Revised Cambridge Reference Sequence and analyzed with the MToolBox pipeline. Results The median age was 57 years; 84.2% had intermediate-1/2 Dynamic International Prognostic Scoring System (DIPSS) score, and 51% received myeloablative conditioning regimens (Table 1). Sequencing achieved a mean depth of 21,067 × with 99.99% coverage, yielding 2,942 mtDNA variants. Consistent with our findings in MDS, the control region (D-Loop) was the most frequently mutated region and MT-ND5 was the most frequently mutated protein-coding gene (10.3%) (Figure 1). A higher burden of mtDNA variants was associated with worse overall survival (OS; HR = 1.03, P = 0.04) and a nominally increased risk of transplant-related mortality (TRM; HR = 1.03, P = 0.05). Gene-based analyses revealed MF-specific associations (Bonferroni threshold P < 3.13 × 10-3): OS with MT-CO3 (P = 7.63 × 10-4); relapse with MT-ND1 (P = 1.79 × 10-3) and MT-ND4 (P = 2.01 × 10-3); and TRM with MT-CYB (P=1.21 × 10-3), MT-ND4 (P=1.18 × 10-3), MT-CO3 (P=5.67 × 10-4), MT-ATP6 (P=2.07 × 10-3) and MT-tRNA (P=8.57 × 10-5) (Table 2). Shared associations with MDS included OS with MT-ND2 (P=9.26 × 10-5), relapse-free survival with MT-ND4 (P=2.99 × 10-4), and relapse with MT-tRNA (P=3.55 × 10-4). Conclusions This study identified novel MF-specific mtDNA variants associated with post-transplant outcomes, alongside shared prognostic effects across myeloid neoplasms. These genes map to the mitochondrial electron transport chain (ETC), which is essential for oxidative phosphorylation. Variants in ETC genes may contribute to tumorigenesis and disease progression by driving abnormal reactive oxygen species production, suggesting mtDNA profiling could refine risk stratification in HCT.

Introduction GvHD is a major post-transplant complication lacking reliable predictive biomarkers. Based on our prior work showing that mtDNA variants in MT-ND4L and MT-ND5 predict transplant outcomes in MDS patients, we investigated mtDNA variants as potential GvHD biomarkers. Objectives Here, we assessed whether donor or recipient mtDNA variants are associated with acute GvHD grades II–IV (aGvHD24), acute GvHD grades III–IV (aGvHD34), and chronic GvHD (cGvHD). Methods Whole-genome sequencing was performed on pre-transplant blood samples from 494 MDS patients (60X) and their donor (30X) who underwent first allo-HCT between 2014 and 2018 through the CIBMTR repository. mtDNA variants were called using the MToolBox pipeline. 1,140 variants are overlapped between patient and donor. Stepwise selection with the Akaike Information Criterion (AIC) was used to identify clinical covariates for each outcome. Associations with GvHD were assessed using Fine-Gray competing risk models adjusted for covariates and principal components. Gene-level effects were evaluated with a modified SKAT-O that we developed for competing risk models. Statistical significance was defined as P < 0.05, with Bonferroni correction for multiple testing. Results Median patient age was 66 years; 63.9% were male, and 71.4% had 8/8 HLA-matched unrelated donors. Overall, 47% developed aGvHD24, 18.6% developed aGvHD34, and 48.1% developed cGvHD. Single-variant analyses identified recipient MT-ND5 m.13830 T>C, p.L498L and donor MT-rRNA m.2581 A>G were associated with aGvHD24; patient MT-tRNA m.10410 T>C and donor MT-ATP8 m.8473 T>C, p.P36P with aGvHD34; and patient MT-ND5 m.12810 A>G, p.W158W and donor MT-ND6 m.14569 G>A, p.S35S with cGvHD (all P < 0.05). Gene-based analyses showed significant associations: aGvHD24 was associated with recipient MT-ND4L (HR = 0.65; P = 0.017) and donor MT-CYB (HR = 1.18; P = 0.025) and MT-rRNA (HR = 1.14; P = 0.003), while cGvHD was associated with donor MT-CO2 (HR = 1.30; P = 0.032) and MT-CO3 (HR = 0.75; P = 0.021). After multiple testing correction, no mtDNA genes remained significantly associated with aGvHD34 or cGvHD, while donor MT-rRNA retained a statistically significant association with aGvHD24. Interaction analyses, assessing if the effect of a recipient variant depends on the donor's variant status, showed reduced aGvHD24 risk when both recipient and donors carried MT-tRNA mutations (HR=0.59; 95% CI 0.36-0.99). Conclusions Donor and recipient mtDNA variants maybe associated with the risk of acute and chronic GvHD risk after allo-HCT. Importantly, gene-based interaction analyses indicate joint assessment of recipient and donor mtDNA enhances GvHD risk prediction, supporting mtDNA profiling as a potential biomarker for alloimmune activation and GvHD risk stratification.

Introduction and Objective Pathogenic or likely pathogenic germline variants (PGVs) occur in ∼10% of myelodysplastic syndrome (MDS) patients as well as in related and unrelated donors. The impact of PGVs in donors (D) and/or recipients (R) on post-allogeneic hematopoietic cell transplantation (HCT) outcomes is unknown. We evaluated post-HCT outcomes in MDS patients where the R and/or D had PGVs. Methods Paired D/R peripheral blood samples from MDS patients undergoing HCT were subjected to whole exome or genome sequencing (30–40x) in two CIBMTR-sponsored studies. Variants in hematologic cancer predisposition genes were quality-filtered and retained if gnomAD allele frequency (AF) ≤0.005 (or ≤0.05 for high-AF genes CHEK2, DDX41). Likely germline classification was based on multiple-criteria decision analysis and/or somatic frequency in COSMIC. ACMG/AMP pathogenicity was manually curated. Outcomes analysis included Fine-Gray competing risk or Cox PH, with multivariable modeling for significant variables. Results In the first cohort (n=404), 13.9% (56/404) of R had PGVs, most commonly DDX41 (1.5%, 6/404), GATA2 (1.2%, 5/404), and SBDS (bi-allelic 0.7%, 3/404; mono-allelic 0.2%, 1/404). All were related D and 9.4% (38/404) had PGVs, most commonly SBDS (bi-allelic 0.5%, 2/404; mono-allelic 0.5%, 2/404), BRCA2 (0.7%, 3/404), and BRIP1 0.7%, 3/404). In the second cohort (N=494), 15.2% (75/494) of R had PGVs, most commonly DDX41 (3.0%, 15/494), RUNX1 (2.6%, 13/494), and CHEK2/BRCA2 (both 1.2%, 6/494). PGVs were seen in 5.2% (5/97) of related D and 4.0% (16/397) of unrelated D, most commonly CHEK2 (0.8%, 4/494), BRCA2 (0.8%, 4/494), and BRCA1 (0.4%, 2/494).Amongst patients in the outcomes cohort (N=842), PGVs were seen in neither donors nor recipients (D-/R-) in 83.8% (706/842), donors only (D+/R-) in 1.8% (15/842), recipients only (D-/R+) in 9.9% (83/842), and both donors and recipients (D+/R+) in 4.5% (38/842). Baseline features are in Table 1. Median age at HCT for D-/R- was 64.5 yrs vs. D+/R+ at 58.1 yrs. The D type was related for D-/R- in 54.7% (386/706) vs. D+/R+ in 92.1% (35/38).Post-HCT outcomes are in Table 2. No differences were seen in cumulative incidence (CI) of primary graft failure (few events) or post-HCT relapse. CI of non-relapse mortality was lower for PGV D+/R+ (hazard ratio (HR) 0.34, p=0.029); this was not significant after covariate adjustment (HR 0.42, p=0.11). There was a significant effect for disease-free survival (DFS) in PGV R+ (HR 0.76, p=0.037), which was robust to covariate adjustment (HR 0.71, p=0.013), and a trend for D+/R+ (HR 0.65, p=0.056). There was no effect on overall survival. Discussion Although PGVs are seen in >5% of donors, their impact on post-HCT outcomes is complex. We found an effect for R+ status on DFS and a trend for D+/R+ status, although unexpectedly in a protective direction. The risk conferred by D/R PGV status is heterogeneous and likely gene specific.

Posttransplant cyclophosphamide (PTCy) to prevent graft-versus-host disease (GVHD) improves outcomes in recipients of HLA mismatched unrelated donor (MMUD) allogeneic hematopoietic cell transplantation (allo HCT). Outcomes of MMUD HCT using PTCy in patients requiring reduced intensity or non-myeloablative conditioning (RIC/NMA) are not well described. The Phase II, prospective, ACCESS trial sought to evaluate PTCy-based GVHD prophylaxis in adult recipients of MMUD using peripheral blood stem cell allografts. Here, we report combined results of RIC/NMA recipients treated in the initial study (N = 70) and a planned expansion cohort (N = 123). The number of centers participating in the expansion protocol was 33 compared to 13 in the initial study. Median participant age was 65.0 (range: 22.9-78.9) and the HCT comorbidity index was high-risk (≥ 3) in 65 (33.7%). Donor HLA matching was < 7/8 in 62 (32.1%) participants. One-year survival was 79.6% (95% confidence interval: 73.2-84.7) and was similar between HLA 7/8- and HLA < 7/8-matched donor recipients. Survival was similar between participants in the initial study (78.6%) and the expansion cohort (80.3%) indicating generalizability of this strategy. One-year incidence of severe infection (Grade 3-5) was 39% (32%-46.9%). The 1-year incidence of non-relapse mortality and relapse estimates were 12.5% (8.3%-17.6%) and 17.3% (12.3%-23%), respectively. MMUD with PTCy-based GVHD prophylaxis and RIC/NMA conditioning was safe and effective to facilitate HCT. Outcomes were similar in the expansion cohort that enrolled from a greater number of centers. Post-HCT infections were prevalent.

ACCESS is a prospective, multicenter phase II trial evaluating peripheral blood stem cell (PBSC) transplantation using 4-7/8 HLA-mismatched unrelated donors (MMUD) with post-transplant cyclophosphamide (PTCy), tacrolimus, and mycophenolate. Adults undergoing first HCT with myeloablative (MAC) or reduced-intensity/nonmyeloablative (RIC/NMA) conditioning were enrolled, with donors aged 18-35 years and matched at 4/8-7/8 HLA loci by high-resolution typing. This expanded analysis includes all enrolled adult PBSC recipients, including the protocol-specified RIC/NMA cohort expansion, to improve precision of outcome estimates and provide descriptive analyses by HLA match level. Among 268 adults, 183 received 7/8 and 85 received <7/8 MMUD grafts; 82.4% of the <7/8 cohort received 6/8 grafts. Median follow-up among survivors was 11.9 months. At 1-year, overall survival was 78.6% (95% CI, 71.9-83.9) in the 7/8 cohort and 85.6% (95% CI, 76.0-91.5) in the <7/8 cohort. One-year relapse, non-relapse mortality, and GVHD-free relapse-free survival were 17.1%, 13.7%, and 51.1% versus 22.8%, 8.4%, and 54.6%, respectively. The cumulative incidence of grade II-IV and grade III-IV acute GVHD by day 100 was 36.6% and 7.7% in the 7/8 cohort versus 28.3% and 5.9% in the <7/8 cohort. Moderate-to-severe chronic GVHD at 1 year was 11.3% versus 7.7%, respectively. Among adult ACCESS recipients treated on a uniform young-donor PBSC/PTCy platform, short-term outcomes with predominantly 6/8 MMUD transplantation were encouraging. Because donor match level was not prospectively assigned and between-group comparisons were exploratory, these findings are descriptive and should not be interpreted as establishing equivalence with 7/8 MMUD transplantation. (Registered as NCT04904588 at CT.gov)

ABSTRACT:The benefit of extended phased (∼) HLA class I∼class III∼class II haplotypes in reducing the mortality after hematopoietic cell transplantation is unknown and requires information on functional class III variation. We identified a robust class III single-nucleotide polymorphism (SNP), rs915654, informative for mortality and relapse in 1436 patients and their haploidentical related donors through multivariable regression analysis of 26 candidate class III SNPs. Three-marker haplotypes, as defined by 1 class I locus, 1 class II locus, and rs915654 were determined in patients separately from donors. Inclusion of rs915654 into relapse and mortality models already containing patient HLA-E∼DRB1 and donor HLA-B∼DRB1 improved each model (likelihood ratio test P = .06 and P = .004, respectively, for relapse; P = .10 and P = .01, respectively, for mortality). The risks of mortality and relapse increased with decreasing numbers of favorable patient and donor markers. Retesting in an independent cohort of 1141 haploidentical transplants yielded similar results. The number of unfavorable markers additionally increased nonrelapse mortality. HLA-A∼C∼B∼DRB1∼DQB1 haplotypes were defined according to their expected numbers of favorable markers, and the theoretical utility for selecting donors was explored. In summary, extended HLA class I∼class III∼class II haplotypes influence the success of transplantation and inform the biology of the major histocompatibility complex in health and disease. The selection of haploidentical donors for future patients may be optimized with knowledge of donor HLA haplotypes.