Development Of GVHD Research Articles

Immune Reconstitution after Allogenic Stem Cell Transplantation in Patients with Myelofibrosis

Background Allogeneic hematopoietic stem cell transplantation (alloHSCT) remains the only curative treatment for patients (pts) diagnosed with myelofibrosis (MF). Despite several improvements over time, post-transplant complications can still be severe and significantly affect pts' survival. Inflammation and bone marrow fibrosis may hinder immune reconstitution (IR) in MF pts, but there is limited data available. This study aimed to evaluate IR in MF pts undergoing alloHSCT and its impact on their outcomes. Methods We retrospectively evaluated IR in MF pts who underwent alloHSCT at the Bone Marrow Transplantation Unit of Spedali Civili di Brescia between April 2017 and April 2024. Absolute lymphocyte counts (ALC) and lymphocyte subtypes were assessed at +3, +6, +9, +12, +18, and +24 months (M) post-transplant. IR was evaluated by flow cytometry using fresh whole blood samples. Monoclonal antibodies were employed to evaluate main lymphocyte populations, CD4/CD8 ratios, and T-cell subset (CD45RA; CD45RO). Lymphocyte recovery was defined as ALC >500/uL at M+3, and ALC >750/uL from M+6 onward. The recovery of subtypes CD3+CD4+, CD3+CD8+ and CD19+ was classified as absolute counts >200/uL. Results Since April 2017, 33 MF pts were transplanted at our Institution. The median age was 60.7 years (range 44-71), with 76% (25) being male. Seventeen out of 29 evaluable pts (59%) had an unfavorable karyotype. Twenty-four pts were JAK2 mutated, while 8 were CALR+ and 1 MPL+. Overall, 13 on 28 evaluable pts harbored a high molecular risk mutation. Five pts had DIPSS intermediate-1, 20 pts had intermediate-2, and 8 had high risk. Twenty-eight pts received JAK2 inhibitor before alloHSCT. Regarding transplant features, 16 pts received a myeloablative conditioning, and 27 received double-alkylators regimens (Thiothepa-Busulfan-Fludarabine). Donors were sibling, unrelated or haploidentical in 18.2%, 48.5% and 33.3% of cases, respectively. HCT-CI was high in 15 pts. Almost all pts (85%) received peripheral blood stem cell grafts. In haploidentical alloHSCT, pts received post-transplant cyclophosphamide, while the other pts received GvHD prophylaxis with cyclosporine and methotrexate (or mycophenolate); 21 pts received rabbit antithymocyte globulin (ATG). After a median follow-up of 15.9 months (IQ 8-43), 12 pts had died (5 relapse, 4 infections, 3 acute GVHD) for a 5-year CIR, NRM and OS of 27.2% (95%CI 10.8-46.7), 19% (95%CI 7.5-34.6) and 54.3% (95%CI 28.5-74.4), respectively. Serial ALC assessments showed a gradual increase from M+3 to M+18. Median counts reached 426/uL (115-1758) at M+3, 587/uL (254-2794) at M+6, 891/uL (148-3181) at M+9, and 1643/uL (438-4978) at M+18, representing 41%, 42%, 53% and 83% of recovered pts, respectively. Similarly, CD4+ recovery improved over time, with median CD4+ counts surpassing 200/uL only at M+9. CD4+ reconstitution at M+3 varied significatively according to donor type: haploidentical alloHSCT had a median of 104/uL, whereas sibling and MUD transplants were 171/uL and 142/uL, respectively (p 0.01). ATG treatment was not related to CD4+ reconstitution. CD4+CD45RA+ cells, more likely naïve cells, significatively increase at each time point, peaking at 37.7/uL at M+18. Conversely, CD3-CD56+/CD16+ NK cells significatively decreased from M+3 to M+24. Pts not reconstituting CD4+ and ALC at M+9 were associated with a higher relapse rate (p 0.05) and showed a trend towards worse overall survival. At M+24, the cumulative incidence of relapse was 33% in pts with less than 200 CD4+/uL at M+9, compared to 0% in those with recovered CD4+ counts (p 0.05). Similarly, pts not recovering ALC at M+9 had relapse CI of 40% at M+24, compared to 0% in those with recovered ALC. ALC and CD4+ recovery at M+9 also impacted the maintenance of chimerism (p 0.05). CD4+ recovery at M+3 and M+6 was associated with a trend towards fewer infections. Additionally, not achieving CD4+ recovery at M+3 was linked to a higher risk of chronic GVHD. Conclusion MF pts exhibit slow immune reconstitution after alloHSCT, with median CD4+ count exceeding 200/uL only after 9 months, and CD4CD45RA+ counts peaking at 18 months. ALC and CD4+ recovery at 9 months is associated with lower late-relapse rates and lower chimerism loss. Despite being influenced by various factors (e.g., donor type), IR after alloHSCT in MF pts can be a valuable tool for assessing the risk of infections, GVHD development, and relapse.

Incidence of Epstein-Barr Virus Reactivation and Its Risk Factors in Allogeneic Hematopoietic Stem Cell Transplant Recipients.

Epstein-Barr virus (EBV) reactivation in allogeneic hematopoietic stem cell transplantation (allo-HCT) recipients can lead to significant complications including post-transplant lymphoproliferative disease. Despite progress in managing EBV reactivation in allo-HCT recipients, data on clinical characteristics and prognostic implications of EBV viral load remain limited. Here, we aim to evaluate the prevalence, identify risk factors, and assess the clinical implications of EBV-DNA positivity in allo-HCT recipients. A retrospective audit of laboratory records for EBV load monitoring in allo-HCT recipients during the period from 2021 to 2023 was performed. EBV viral load was assessed using quantitative PCR. The medical records were reviewed for clinical features, identifying risk factors, and prognostic impact of EBV-DNA positivity. A total of 40 patients with a median age of 20.5 years were included. Patients were divided into two groups based on presence (>600 copies/mL) and absence of EBV-DNA. We observed EBV-DNA positivity in 16 (40%) patients with a median EBV viral load of 12,400 copies/ml. Patients with EBV-DNA positivity exhibited a higher incidence of acute graft versus host disease (p=0.039). Patients with EBV-DNA positivity tended to have poorer 1-year overall survival and disease-free survival, although the results did not reach statistical significance. Our data highlights the importance of monitoring EBV viral load in predicting the outcome in terms of overall survival in allo-HCT recipients. The development of GVHD has also surfaced as a significant element increasing the likelihood of EBV-DNA positivity. It is imperative to conduct further research and establish comprehensive protocols for the routine monitoring and management of EBV post-allo-HCT.

The CD28 IVS3 + 17 T/C polymorphism and the GVHD occurrence in Tunisian patients receiving an HLA–identical sibling HSCs transplant

Graft-versus-host disease (GVHD) is a potentially serious complication ofallogeneic hematopoietic stem cell transplantation (HSCT). Graft-contaminating T cells (donor T cells) arecrucial for the development ofGVHD since they are able to react against the recipient’s antigens. In this study we aim toevaluatethepotentialassociation between the IVS3 + 17 T/C gene variation in the CD28 molecule, a T cells costimulatory factor, and the GVHD occurrence in a Tunisian group of recipients of allo-HSCTs. Results show that there is an association between the presence of this polymorphism and the occurrence of grades II–IV acute GVHD (OR: 2.470, I.C: 1.027–5.938, p = 0.043). As for the chronic GVHD, it seems that the studied gene variation has no impact on the occurrence of this complication, which appeared likely to be affected by the HSCT graft source (PBSC: peripheral blood stem cells) (OR: 5.141, I.C: 1.590–16.620, p = 0.006). Based on these data, we believe that the CD28 IVS3 + 17 T/C polymorphism is a significant factor in the pathogenesis of acute GVHD.

Cytomegalovirus infection is associated with thymic dysfunction and chronic graft-versus-host disease after pediatric hematopoietic stem cell transplantation

Pediatric hematopoietic stem cell transplantation (HSCT) is challenged by chronic graft-versus-host disease (cGvHD) significantly affecting survival and long-term morbidity, but underlying mechanisms including the impact of post-HSCT CMV infection are sparsely studied.We first investigated the impact of CMV infection for development of cGvHD in 322 children undergoing standard myeloablative HSCT between 2000 and 2018. Clinically significant CMV infection (n = 61) was an independent risk factor for chronic GvHD in a multivariable Cox regression analysis (HR = 2.17, 95% CI = 1.18–3.97, P = 0.013). We next explored the underlying mechanisms in a subcohort of 39 children. CMV infection was followed by reduced concentration of recent thymic emigrants (17.5 vs. 51.9 × 106/L, P = 0.048) and naïve CD4+ and CD8+ T cells at 6 months post-HSCT (all P < 0.05). Furthermore, CD25highFOXP3+ Tregs tended to be lower in patients with CMV infection (2.9 vs. 9.6 × 106/L, P = 0.055), including Tregs expressing the naivety markers CD45RA and Helios. CD8+ T-cell numbers rose after CMV infection and was dominated by exhausted PD1-expressing cells (66% vs. 39%, P = 0.023).These findings indicate that post-HSCT CMV infection is a main risk factor for development of chronic GvHD after pediatric HSCT and suggest that this effect is caused by reduced thymic function with a persistently impaired production of naïve and regulatory T cells in combination with increased peripheral T-cell exhaustion.

Single-cell RNA-sequencing reveals the transcriptional landscape of lacrimal gland in GVHD mouse model

PurposeTo investigate the global transcriptional landscape of lacrimal gland cell populations in the GVHD mouse model. MethodsSingle-cell RNA sequencing and further bioinformatic analysis of dissociated lacrimal gland (LG) cells from the mouse model were performed. Parts of transcriptional results were confirmed by immunofluorescence staining. ResultsWe identified 23 cell populations belonging to 11 cell types. In GVHD LG, the proportion of acinar cells, myoepithelial cells, and endothelial cells was remarkably decreased, while T cells and macrophages were significantly expanded. Gene expression analysis indicated decreased secretion function, extracellular matrix (ECM) synthesis, and increased chemokines of myoepithelial cells. A newly described epithelial population named Lrg1high epithelial cells, expressing distinct gene signatures, was exclusively identified in GVHD LG. The fibroblasts exhibited an inflammation gene pattern. The gene pattern of endothelial cells suggested an increased ability to recruit immune cells and damaged cell-cell junctions. T cells were mainly comprised of Th2 cells and effective memory CD8+ T cells. GVHD macrophages exhibited a Th2 cell-linked pattern. ConclusionsThis single-cell atlas uncovered alterations of proportion and gene expression patterns of cell populations and constructed cell-cell communication networks of GVHD LG. These data may provide some new insight into understanding the development of ocular GVHD.

Sustained cross-talk between donor T cells and IL-33+ stromal cells maintains CD4 T cell differentiation and determines GVHD outcomes

Abstract Conditioning before allogeneic hematopoietic stem cell transplantation (AlloHSCT) increases the tissue injury signal IL-33 in fibroblastic reticular cells (FRC). Released IL-33 directly stimulates donor CD4 T cells to prime IL-12-independent Type 1 T helper cell (Th1) differentiation and expansion. Tissue stroma upregulates IL-33, but a role for IL-33 in sustaining the pathogenic donor Th1 responses causing GVHD is unclear. We compared B6 mice with inducible ST2 deletion (R26-CreERT2xSt2fl/fl) to wildtype (WT) R26-CreERT2 as T cell donors in a lethal GVHD model (B6 to BALB/c). Donor ST2 deletion at days 10-14 post AlloHSCT increased CD4 T cells Foxp3 expression with reciprocal decreases in Tbet expression in both the lymphoid organs and target tissues. Sustained IL-33 signaling also maintained donor T cell TCF1 expression. Ablating ST2 after GVHD development improved clinical scores and promoted recipient weight gain. How bioactive IL-33 is released from nuclear sequestration remains undefined. RNAseq analysis suggested that IL-33 stimulates T cell granzyme B (GzmB) expression and B6 GzmB deficient (Gzmb-/-) donor T cells displayed reduced activation and expansion similar to ST2 deficient CD4 T cells. In contrast to GzmBWT, anti-IL-33 antibodies had no impact on GzmBKO T cell responses. Thus, cross-talk between donor T cells and IL-33+ stroma orchestrates the T cell identities that are critical to sustain the pathogenic CD4 T cell responses causing GVHD.

Late Relapse after Allogeneic Stem Cell Transplantation in Patients Treated for Acute Myeloid Leukemia: Relapse Incidence, Characteristics, Role of Conditioning Regimen, and Outcome.

Late relapse, beyond 2 years following alloHSCT for AML, is rare. Among the 376 patients allografted for AML in our center between 1990 and 2016, 142 (38%) relapsed. The majority (68%) of relapses occurred during the first year following transplantation. Beyond 2 years after alloHSCT, relapse was observed in 26 patients, representing 6.9% of the whole transplanted cohort and 18.3% of the relapsing patients. Cytogenetics at relapse was available in 21 patients and remained for 15 of them concordant to that at diagnosis. The majority (85.7%) of the patients were in CR prior to transplant. Thirteen patients had grade 1-2 acute GvHD, while 13 other patients had grade 3-4 acute GvHD. None of these patients subsequently developed chronic GvHD. In multivariate analyses, a predictive factor of the absence of relapse 2 years after transplantation was the development of extensive chronic GVHD. Salvage therapy achieved new CR in 77% of these patients. We conclude that late relapse can affect a significant minority of patients allografted for AML, and the intensity of the conditioning regimen does not seem to have an impact on these relapses. Moreover, we were able to show that those patients can receive effective salvage therapy.

Transplantation of Donor-Recipient Chimeric Cells Restores Peripheral Blood Cell Populations and Increases Survival after Total Body Irradiation-Induced Injury in a Rat Experimental Model.

Current therapies for acute radiation syndrome (ARS) involve bone marrow transplantation (BMT), leading to graft-versus-host disease (GvHD). To address this challenge, we have developed a novel donor-recipient chimeric cell (DRCC) therapy to increase survival and prevent GvHD following total body irradiation (TBI)-induced hematopoietic injury without the need for immunosuppression. In this study, 20 Lewis rats were exposed to 7 Gy TBI to induce ARS, and we assessed the efficacy of various cellular therapies following systemic intraosseous administration. Twenty Lewis rats were randomly divided into four experimental groups (n = 5/group): saline control, allogeneic bone marrow transplantation (alloBMT), DRCC, and alloBMT + DRCC. DRCC were created by polyethylene glycol-mediated fusion of bone marrow cells from 24 ACI (RT1a) and 24 Lewis (RT11) rat donors. Fusion feasibility was confirmed by flow cytometry and confocal microscopy. The impact of different therapies on post-irradiation peripheral blood cell recovery was evaluated through complete blood count, while GvHD signs were monitored clinically and histopathologically. The chimeric state of DRCC was confirmed. Post-alloBMT mortality was 60%, whereas DRCC and alloBMT + DRCC therapies achieved 100% survival. DRCC therapy also led to the highest white blood cell counts and minimal GvHD changes in kidney and skin samples, in contrast to alloBMT treatment. In this study, transplantation of DRCC promoted the recovery of peripheral blood cell populations after TBI without the development of GVHD. This study introduces a novel and promising DRCC-based bridging therapy for treating ARS and extending survival without GvHD.

Longitudinal Changes of Ocular Surface Microbiome in Patients Undergoing Hemopoietic Stem Cell Transplant (HSCT).

To evaluate changes in the ocular surface microbiome (OSM) between pre- and post-haemopoietic stem cell transplant (HSCT) in the same patient, and to assess the potential impact of these changes in ocular graft-versus-host disease (o)GVHD development. Lower fornix conjunctival swabs of 24 patients were obtained before and after HSCT and subjected to DNA extraction for amplification and sequencing of the V3-V4 regions of the bacterial 16S rRNA gene. The obtained reads were reconstructed, filtered, and clustered into zero-radius operational taxonomic units (zOTUs) at 97% identity level before taxonomic assignment, and biodiversity indexes were calculated. Transplant characteristics were recorded, and dry eye was diagnosed and staged 1-4 according to the Dry Eye WorkShop (DEWS) score. No significant difference in OSM alpha diversity between pre- and post-transplant was found. A significant difference in beta diversity was observed between patients with a DEWS score of 1 versus 3 (p = 0.035). Increased corneal damage between pre- and post-HSCT was significantly associated with a decrease in alpha diversity. The changes in OSM were not associated with oGVHD, nor with any transplant parameter. This preliminary study is the first study to analyse changes in the OSM before and after HSCT longitudinally. No trend in OSM biodiversity, microbial profile, or overall composition changes before and after HSCT was significant or associated with oGVHD onset. The great variability in the observed OSM profiles seems to suggest the absence of a patient-specific OSM "signature".

Planning GvHD preemptive therapy: risk factors, biomarkers, and prognostic scores.

Prevention of acute and chronic graft-versus-host disease (aGvHD and cGvHD) is an important objective of allogeneic hematopoietic cell transplantation (HCT). While there is has been significant progress in preventative approaches in the peritransplant period to minimize development of GvHD, no preventative approach has completely eliminated development of either aGvHD or cGvHD. Recently, posttransplant immune biomarker profiling early post-HCT by the Mount Sinai Acute GvHD International Consortium group has resulted in a validated risk assignment algorithm and development of preemptive approaches to decrease aGvHD and mortality in high-risk patients. cGvHD risk assignment algorithms have been developed based on measurements at day 100 and may be used for future preemptive intervention trials to minimize cGvHD. This article discusses the current state of the art in aGvHD and cGvHD preemptive algorithms and therapeutic interventions and what is needed to move these into validated approaches.

Soluble LAG3: A Potential Marker for the Development and Activity of Acute Graft-Versus-Host Disease

Acute graft-versus-host disease (aGVHD), usually developing within 100 days after hematopoietic stem cell transplantation (HSCT), is mainly attributed to donor T cell pro-inflammatory responses against mismatched host histocompatibility antigens. The persistence of increased effector T cell responses following HSCT is partially related to an altered function of T regulatory cells (Tregs) and their failure to prevent GVHD. Certain immune checkpoint molecules, such as cytotoxic T-lymphocyte antigen 4, programmed cell death protein 1 (PD1) and lymphocyte activation gene-3 (LAG3), highly expressed on Tregs, are involved in maintaining immune tolerance and preventing immune-mediated inflammation. LAG3 is a newly identified inhibitory receptor, found on most immune cells, including CD4+ and CD8+ T cells, Tregs, and dendritic cells. Previous studies have demonstrated a role of LAG3 expression on T cells in GVHD suppression. Its soluble isoform sLAG3, released from the cell membrane, has been recently reported to also contribute to enhanced immune-mediated responses in solid tumors and autoimmune diseases, such as anti-PD1-resistant melanoma, rheumatoid arthritis (RA), and ANCA-associated vasculitis. Given this evidence, the current study aimed to explore a potential role of sLAG3 in GVHD development. Serum samples of 25 patients (≥18 years old) who underwent allogeneic HSCT at Rambam from 01.2021 to 01.2023 were drawn on days -7, +100, +180 of transplant. Twelve serum samples obtained from the Biobank were used as healthy control (HC). All samples were assessed for the sLAG3 levels using a commercial ELISA kit. The median level measured in HC (56pg/mL) was considered a cutoff to define the “low and high level sLAG3 groups”. Twenty-three patients were included in the analysis [median age at transplant - 59.5 years (range 19-75); 52% males]. Seventeen patients had acute myeloid leukemia, 3 - myelodysplastic syndrome, 2 - acute lymphoblastic leukemia and 1 had primary myelofibrosis. Fourteen patients had a matched unrelated donor, 6- matched related donors, and 3 - haploidentical donors. Nineteen patients received calcineurin inhibitor (CNI) and methotrexate-based GVHD prophylaxis (13 with ATG); 4 patients received post-transplant cytoxan-based prophylaxis, with CNI and mycophenolate-mofetil. Overall, 17/23 (74%) patients developed GVHD: 9 - aGVHD and 8 - chronic GVHD (cGVHD). A low pre-transplant sLAG3 level (&amp;lt;56pg/mL) was found in 8/23 patients, while it was high (&amp;gt;56pg/mL) in 15/23. Notably, 9/15 (60%) patients in the “high sLAG3 group”, but none in the “low sLAG3 group” were diagnosed with aGVHD, suggesting a high sLAG3 level as a possible indicator for patient-pre-transplant susceptibility to aGVHD development, irrespective of transplant factors, such as conditioning regimen, donor type, etc. Four patients in each group developed cGVHD. Furthermore, there was a significant increase in sLAG3 levels between the baseline and GVHD diagnosis in patients who developed aGVHD (mean: from 156.1±172.8, to 323.9±201.3), but not in those who either had cGVHD (mean: from 119.71±90.5 to 150.1±147.1) or did not have GVHD (mean: from 49.7±36 to 52.1±22.2). Overall, 11/23 patients were in complete remission (CR) at the time of HSCT; 9/11 were in the high-sLAG3 group and 6 of them developed aGVHD. In the low-sLAG3 group, most patients (6/8) had some degree of active disease (persistent disease or minimal-residual disease). These findings may reflect high T-effector cell and/or low Treg activity, possibly contributing to both anti-leukemic effect and GVHD development. In conclusion: The current study demonstrates, for the first time, that the pre-transplant sLAG3 level is significantly increased and continues to further increase in patients who develop aGVHD following HSCT compared to those who don't. These findings suggest a potential role of sLAG3 as a predicting factor for aGVHD development as well as a marker of treatment response that could guide therapeutic decisions in this patient setting.

Combined Cytokine Blocking Therapy (CCBT) Using Basiliximab and Infliximab for Treatment of Steroid-Refractory Graft Versus Host Disease (SR-GvHD)

Background Despite improved advances in graft-vs-host disease (GvHD) prophylaxis regimens and post-allogeneic hematopoietic cell transplant (HCT) supportive care, clinically significant acute GvHD still develops in approximately 30-50% of HCT recipients (Lazaryan A et al. BMT 2016) and often results in increased transplanted-related morbidity and mortality and deterioration of quality of life (Choi J et al. Blood 2012). Standard first-line treatment is high-dose glucocorticoids have been limited including recently approved JAK2 inhibitor (ruxolitinib). The utilization of combined cytokine blockade therapy (CCBT) with the monoclonal antibodies infliximab (a TNF-α inhibitor, INF) and basiliximab (an IL-2 receptor blocker, BAS), has had limited discussion in the literature despite common utilization. The primary objective of this retrospective study was to determine overall response rate (ORR) at days 7, 14 and 28 for CCBT. Secondary outcomes included non-relapse mortality (NRM), and overall survival (OS). Methods 60 patients who met the inclusion criteria were analyzed. Patients included were ≥18 years old and had undergone HCT using any donor or graft source with any conditioning regimen between 2010-2021 at City of Hope Medical Center in Duarte, CA. Patients had steroid refractory aGvHD, according to Mount Sinai Consortium guidelines (Harris AC et al. BMT 2016) and received at least one dose of BAS and at least one dose of INF. Patients with &amp;gt;1 allogeneic transplant, chronic GVHD including overlap syndrome, relapse of primary disease, graft loss, and glucocorticoid treatment for indications other than GVHD were excluded. Treatment BAS was administered intravenously as 20mg doses given first as loading doses on days 1 and 4. Subsequent doses were given weekly starting 7 days after the final loading dose (day 4). INF was administered as 10 mg/kg doses infused weekly. Tacrolimus, sirolimus and cyclosporine dosing and monitoring were performed in accordance with institutional policies. All patients had clinical presentation of SR-GVHD defined as ≥1 of the following: GVHD increasing in stage in any organ or developing in a new organ after 3 days of ≥2 mg/kg methylprednisolone (MSPE) or equivalent, GVHD that has not improved in stage in ≥1 organ after 7 days of ≥2 mg/kg MSPE or equivalent, development of GVHD in a new organ after ≥1 mg/kg MSPE or equivalent for skin GVHD or patients who progress during tapering before a 50% decrease in glucocorticoids is achieved. Results The median age was 53 years (range, 5-78) at time of HCT. Of 60 patients, 65% were males and with 18.3% of male patients receiving grafts from female donor. HCT-CI at the time of HCT was 3 or more in 47% of the patients. Conditioning for those patients was ablative in 43.3% of patients with 76.7% of patients receiving PBSC grafts from mostly MSD/MUD in 75% of patients. Most patients had grade 3 or 4 overall acute GVHD (grade 3: n=35, 58.3%, grade 4: n=20, 33.3%). Median time to start of BAS after start of steroid was 7 days while time to start of INF after steroid was 11 days. Ruxolitinib was initiated in 33.3% (20/60) of patients prior to CCBT. ORR for CCBT therapy at day 7, 14, and 28 were 28.3% (17/60; CR 5.0%), 38.3% (23/60; CR 11.7%), and 38.3% (23/60; CR 23.3%), respectively. Patients who received ruxolitinib prior to CCBT had lower ORR (25%) compared to those who did not (47.5%). 37 patients died-20 of aGVHD, 4 of infection, 1 of sudden cardiac death and 1 of leukemia relapse. OS was 41.7% at 6 months and 36.5% at 12 months (Figure 1A). Cumulative incidence of NRM was 51.7% at 6 months and 55% at 12 months (Figure 1B). Cumulative incidence of any cGvHD was 33.6% at 12 months while it was 30% for extensive cGvHD at the same 12-month interval. In patients with and without ruxolitinib initiated prior to CCBT, OS at 12 months was 30% vs 40%, respectively (Figure 2A) while NRM at 12 months was 65% and 50%, respectively (Figure 2B). Conclusion CCBT has potential efficacy in steroid refractory aGVHD. The observed ORR is reflective of both advanced and highly refractory aGVHD with one-third of patients progressing on ruxolitinib. Given the favorable observed ORR in this difficult to treat population, CCBT is a potentially promising approach and suitable alternative in the second line or as salvage therapy in patients failing Ruxolitinib.

PB CD8 T N and CD4 T EM on day30 after Allo-HSCT Is a Predictive Marker for the Development of aGVHD

Introduction ： Acute GVHD (aGVHD) is a common complication 20-60 days after allo-HSCT and can be life-threatening in some cases. It has been reported to be associated with T-cell immune reconstitution, but the detailed mechanisms are not clear. Early post-transplant lymphocyte recovery is mainly due to homeostatic peripheral expansion (HPE), which is variable depending on various factors such as donor source, recipient's age. T cell-related cytokines, such as sIL-2R , IL-7 and TNFr1 are known biomarkers for the aGVHD, but there are few reports that predict the aGVHD incidence rate using the peripheral blood (PB) lymphocyte subset. We evaluated the effect of PB lymphocyte subset in early post-transplant period on aGVHD. Methods ： We retrospectively analyzed 83 patients (40 in AML, 12 in ALL, 1 in MPAL, 13 in MDS, 2 in MPN, 9 in malignant lymphoma/LPD and 3 in AA) who underwent the allo-HSCT in our hospital from 2013 to 2023. The median age of patients was 44 years (range:17-66). Sixteen received BM, 47 received PB (including 28 with haploidentical (9 with ATG, 19 with PTCY)), and 20 received CB. GVHD prophylaxis was FK506+MTX in 61 patients, CyA+MTX in 3 and MMF+FK506+CY in 19. The median observation period was 495 [38-2983] days. PB lymphocyte subset (Naïve Tcell (T N):CD45RA+CD62L+, Central memory Tcell (T CM) :CD45RA-CD62L+, Effector memory Tcell (T EM) :CD45RA-CD62L-, Effector memory Tcell re-expressed CD45RA (T EMRA) :CD45RA+CD62L-, Th1:CD3+4+CXCR3+CCR6-, Th2:CD3+4+CXCR3-CCR6-, Th17:CD3+4+CXCR3-CCR6+) at day30 (range:28-35) after transplantation were analyzed by FCM. Results ： Twenty-five patients had grade II-IV aGVHD, and 11 had grade Ⅲ-IV aGVHD. Patients with Grade II-IV aGVHD exhibited significantly lower proportion of CD8+T N as compared to non aGVHD groups (GVHD+: 17.7 ± 13.3%; GVHD-: 30.9 ± 16.3%; p &amp;lt; 0.001) . In contrast, the proportion of CD4+T EM and CD8+T EM were higher in the Grade II-IV acute GVHD group (GVHD+: 30.9 ± 23.1%; GVHD-: 21.9 ± 15.6%; p=0.04, GVHD+: 36.1 ± 16.2%; GVHD-: 22.7 ± 14.7%; p &amp;lt; 0.001, respectively). We found a strong statistical correlation between the proportion of CD8+T N and CD8+T EM. The cumulative incidences of Grade II-IV and III -IV acute GVHD at day + 100 for CD8+T N &amp;lt;20% group was 56.9% and 29.6% compared with 14.2% and 6.3% for the CD8+T N &amp;gt;20% group (p &amp;lt; 0.001 and p &amp;lt; 0.01). Similarly, the cumulative incidences of Grade II-IV and III -IV acute GVHD at day + 100 for CD4+T EM &amp;gt;30% group was 48.1% and 32.6% compared with 22.2% and 5.9% for the CD4+T EM &amp;lt;30% group (p= 0.02 and p &amp;lt; 0.01). Two-year NRM was higher in the CD8+T N &amp;lt;20% group than in the CD8+T N &amp;gt;20% group (26.3% vs 4.2%, p=0.008). The two-year cumulative incidence of relapse (CIR) was comparable between the two groups, but tended to be lower in the mismatched CR group (CD8+T N &amp;lt;20%: 33.1% versus CD8+T N &amp;gt;20%: 43.4%, p=0.31). Conclusion ： PB CD8 T N and CD4 T EM fraction on day30 is a predictive biomarker for the development of acute GVHD.

Allogeneic Hematopoietic Cell Transplant Recipients Carrying DNMT3A and ASXL1 Mutations More Frequently Develop Severe Graft Versus Host Disease and Arterial Hypertension

Background: Clonal hematopoiesis of indeterminate potential (CHIP) is defined as the presence of an expanded blood-cell clone due to acquired somatic mutations in hematopoietic stem cells without evidence of hematologic malignancy, dysplasia or cytopenia. CHIP associates with an increased risk of hematologic malignancies, as well as a pro-inflammatory state and an increased risk for cardiovascular disease. Inflammation furthermore plays crucial roles in the pathogenesis of arterial hypertension (aHTN), which we thus hypothesized may be also induced by CHIP. The epigenetic regulators DNMT3a and ASXL1 count to the most commonly mutated genes in CHIP. While donor CHIP mutations were previously associated with an increased risk for acute Graft versus Host Disease (GVHD), we here report that patients with DNMT3A or ASXL1 mutations in pre-transplant samples also show an enhanced risk for the development of severe (stadium III/IV and systemically treated) GvHD as well as arterial hypertension (aHTN). Methods: We retrospectively analyzed a cohort of 129 patients with myeloid malignancies (74 AML, 25 MDS, 5 CMML, 25 MPN) treated with allo-HCT at our University Hospital between January 2020 and April 2023. Next generation sequencing data performed on bone marrow samples collected maximum one month prior to allo-HCT were analyzed and correlated with the prevalence of pre-transplant diagnosed aHTN (n=129 analyzed patients) and the development of post-transplant GvHD at 3 months post-allo-HCT (n=108 analyzed patients). Results: DNMT3A and/or ASXL1 mutations were surprisingly common and detected in 78/129 patients (61%), (DNMT3A-mutations: 42/129, 33%; ASXL1-mutations: 44/129 (34%); double mutations: 8/129, 6%). Patients with pre-transplant detectable DNMT3A/ASXL1 mutations in the bone marrow showed an increased risk to develop GvHD within 3 months post-transplant and more frequently showed severe GvHD (28/61, 46%) vs. patients with no detectable DNMT3A or ASXL1 mutations (overall GvHD: 34/61, 56% vs. 16/47, 34%, p&amp;lt;0.05; severe GvHD: 28/61, 46% vs. 12/47, 25.5%, p&amp;lt;0.05). Broken down to single mutations: DNMT3A mutation carriers showed a tendency for increased overall GvHD incidence when compared to patients with no detectable DNMT3A or ASXL1 mutations (19/35, 54,3%, versus 12/47, 25.5%, p=0.07), whereas ASXL1 mutation carriers showed significantly higher overall GvHD incidence compared to patients with no detectable DNMT3A or ASXL1 mutations (19/32, 59,4%, vs. 16/47, 34% , p&amp;lt;0.05). The frequency of severe GvHD was significantly higher in both DNMT3A (17/35, 48.6%, p&amp;lt;0.05) and ASXL1 mutation carriers (16/32, 50%, p&amp;lt;0.05) when compared to patients with no detectable DNMT3A or ASXL1 mutations(12/47, 25.5%). DNMT3A/ASXL1-mutation carriers had more frequently arterial hypertension compared to patients with no detectable DNMT3A or ASXL1 mutations(54/78, 69% vs. 22/51, 43%, p&amp;lt;0.05). DNMT3A mutation carriers showed in 28/42 (66.7%) of cases aHTN, whereas ASXL1 mutation carriers showed in 32/44 (72.7%) of cases aHTN, and thus in both categories significantly (p&amp;lt;0.05) higher aHTN rates compared to patients with no detectable DNMT3A or ASXL1 mutations (22/51, 43% with aHT). The presence of DNMT3A/ASXL1 mutations did not delay the time to the engraftment of neutrophils (25.1 vs. 20.5 days in DNMT3A/ASXL1 carriers compared to patients with no detectable DNMT3A or ASXL1 mutations, p=0.64) or thrombocytes (25.6 days vs. 22.6 days, p=0.89). Interestingly, the relapse rates were by trend lower in DNMT3A/ASXL1 carriers when compared to patients with no detectable DNMT3A or ASXL1 mutations in the pre-transplant bone marrow sample (19,1% vs. 28%, p=0.33), although higher numbers of patients need to be analyzed to ensure whether these effects are significant. Conclusion: ASXL1 and DNMT3A mutations are commonly documented in patients with myeloid malignancies undergoing allo-HCT, and associate with increased rates of severe acute GvHD and pre-transplant arterial hypertension, but perhaps with lower relapse probability in the post-transplant setting. The biologic mechanisms underlying these observations are under further investigation. An extended follow-up of these patients shall be presented at the meeting.

Acute Steroid-Refractory Gastrointestinal Graft-Versus-Host Disease Is Not Associated With Significant Differences in Gut Taxonomic Composition Compared to Steroid-Sensitive Gastrointestinal Graft-Versus-Host Disease Immediately Before Onset of Disease

Taxonomic composition of the gut microbiota at the time of neutrophil engraftment is associated with the development of acute gastrointestinal graft-versus-host disease (GI GVHD) in patients undergoing allogeneic hematopoietic stem cell transplantation. However, less is known about the relationship between the gut microbiota and development of steroid-refractory GI GVHD immediately before the onset of disease. Markers of steroid-refractory GI GVHD are needed to identify patients who may benefit from the early initiation of non-corticosteroid-based GVHD treatment. Our aim was to identify differences in taxonomic composition in stool samples from patients without GVHD, with steroid-responsive GVHD and with steroid-refractory GI GVHD to identify predictive microbiome biomarkers of steroid-refractory GI GVHD. We conducted a retrospective case-control, single institution study, performing shotgun metagenomic sequencing on stool samples from patients with (n = 36) and without GVHD (n = 34) matched for time since transplantation. We compared the taxonomic composition of the gut microbiome in those with steroid-sensitive GI GVHD (n = 17) and steroid-refractory GI GVHD (n = 19) to each other and to those without GVHD. We also performed associations between steroid-refractory GI GVHD, gut taxonomic composition, and fecal calprotectin, a marker of GI GVHD to develop composite fecal markers of steroid-refractory GVHD before the onset of GI disease. We found that fecal samples within 30 days of GVHD onset from patients with and without GVHD or with and without steroid-refractory GI GVHD did not differ significantly in Shannon diversity (alpha-diversity) or in overall taxonomic composition (beta-diversity). Although those patients without GVHD had higher relative abundance of Clostridium spp., those with and without steroid-refractory GI GVHD did not significantly differ in taxonomic composition between one another. In our study, fecal calprotectin before disease onset was significantly higher in patients with GVHD compared to those without GVHD and higher in patients with steroid-refractory GI GVHD compared to steroid-sensitive GI GVHD. No taxa were significantly associated with higher levels of calprotectin.

AMPK Controls Glycolytic Compensation in Gvhd-Causing T Cells

Background: The heightened metabolic requirements of alloreactive T cells following allogeneic stem cell transplantation represents a promising area for therapeutic intervention. We have shown that during the initiation of acute graft-versus-host-disease (aGVHD), murine T cells upregulate activity of AMP-activated protein kinase (AMPK), a cellular energy sensor that regulates oxidative and mitochondrial metabolism. Further, transfer of allogeneic T cells deficient in AMPK (AMPK KO) increased recipient survival and decreased disease severity while still preserving leukemia clearance. In the current studies, we demonstrate a novel role for AMPK in controlling glycolytic compensation, both in vitro and vivo, and provide a mechanism as to why cells lacking AMPK are unable to perform this vital function. Together, these data highlight the potential clinical utility in targeting metabolic decision-making to curtail T cell-mediated inflammatory responses, with significant therapeutic implications for the prevention and treatment of aGVHD. Methods: AMPK-deficient murine T cells from AMPKa1/a2 dKO C57BL/6J mice were transplanted into allogeneic B6D2F1 recipients and recovered on day 7 post-transplant. To delete AMPK in primary human T cells, T cells were isolated from healthy donors and electroporated with Cas 9 ribonucleoprotein complexes targeting the AMPKa1 locus. Glycolytic compensation was assessed by measuring extracellular acidification rates (ECAR) using the Agilent Seahorse analyzer and a mitochondrial stress kit. Intracellular cytokine expression for IFNgamma was assessed in day 7 murine T cells following re-stimulation with F1 splenocytes in the presence of Brefeldin A. Aldolase A and glyceraldehyde 3-phosphate dehydrogenase (GAPDH) enzymatic assays were run on cell lysates with Biovision-Abcam kits according to manufacturer instructions. To measure GAPDH activity, T cells were positively selected for CD45.1 from day 7 recipient spleens, followed by cell lysis and detection of enzymatic activity. Results: AMPK KO murine T cells recovered on day 7 were unable to mediate a compensatory increase in glycolysis following inhibition of the electron transport chain (Figure 1A), (-6.499±5.156 vs 29.11±7.064, p&amp;lt;0.0001). Human T cells lacking AMPK gave similar results, with glycolytic compensation impaired both in vitro and following human T cell expansion in vivo in a xenogeneic model of GVHD. Immunoprecipitation of proteins from day 7 murine T cells, using an antibody specific to phosphorylated AMPK targets, recovered lower levels of multiple glycolytic enzymes including aldolase, enolase, pyruvate kinase M, and GAPDH (Figure 1B). Functionally, murine T cells lacking AMPK exhibited impaired aldolase activity following anti-CD3/CD28 stimulation and a decrease in GAPDH activity on day 7 post-transplant. Importantly, these changes in glycolysis correlated with an impaired ability of AMPK KO T cells to produce significant amounts of IFNγ upon antigenic re-stimulation with F1 splenocytes. Discussion: Our results demonstrate that in addition to influencing oxidative metabolism, AMPK also plays a role in glycolytic metabolism during GVHD in both murine and human T cells. Further, our data suggest that the more prominent lesion in human T cells post-transplant was in glycolysis , a result supported by the novel observation that a set of glycolysis-related proteins are immunoprecipitated together at much lower rates in the absence of AMPK. These findings suggest a model in which AMPK phosphorylation provides a nidus for important interactions among glycolytic enzymes and that in the absence of AMPK, these interactions are lessened, and glycolysis is consequently reduced. Important to our understanding of GVHD pathogenesis, rates of T cell glycolysis can be directly linked to IFNγ production, where reduced glycolytic activity frees GAPDH to sequester IFNγ transcripts and thereby limit IFNγ protein translation. Altogether, these results document a prominent role for AMPK in controlling T cell glycolytic activity during GVHD development and offer an additional mechanistic explanation for the decreased severity of GVHD seen following transplantation of AMPK KO T cells. Consistently similar results in human xenogeneic T cells provides a further strong rationale for development of AMPK inhibition as a clinically translatable strategy for GVHD prevention and treatment.

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

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

Cryopreservation Changes the Immune Effector Cell Composition of Peripheral Blood Stem Cell Grafts: An Analysis from the DKMS and NMDP Graft Composition Study

The impact of the cellular composition of PBSC grafts on the immune reconstitution as well as graft-versus-host and graft-versus-leukemia effects after allogeneic hematopoietic cell transplantation (alloHCT) is only poorly understood. DKMS and NMDP joined forces to comprehensively characterize the cellular composition of 2,000 PBSC products using a 34-color flow cytometry panel to define immune effector cell subsets of interest and hematopoietic stem cells. In parallel, we have created a biobank of unstimulated donor PBMC and PBSC graft samples for future analyses. As part of this larger effort, we investigated the effect of cryopreservation on the cellular composition of PBSC products. Cryopreservation of PBSC grafts was used frequently during the COVID19-pandemic and facilitated more flexible timelines for transplantation. Still, one third of the US patients and 15% of the German patients continue to receive cryopreserved PBSC grafts. Ongoing studies are investigating the impact of cryopreservation on immune-effector cell function and the outcome of hematopoietic stem cell transplantation. Several observational studies have reported delayed neutrophil and platelet engraftment with cryopreserved products. More recently, less chronic GVHD was reported for patients who had received cryopreserved PBSC products. Cryopreservation affects the cellular composition and hence has the potential to change immune effector cell functions of the graft, but available data on the alterations of cell population frequencies are scarce. We analyzed the cellular composition of 20 fresh grafts and compared them to their frozen and thawed counterparts. Cryopreservation of product samples followed routine clinical procedures using a 10% DMSO containing cryo-medium and a controlled rate freezing. After thawing at 37°C, cells were washed, stained with a 34-parameter phenotyping panel, fixed and analyzed immediately on a full spectrum flow cytometer. Following spectral unmixing and manual spillover correction, proportions of immune cells were assessed using manual gating. First, we investigated the relative frequencies of 10 non-overlapping individual cell populations relative to viable CD45+ cells, including several lymphocyte populations, monocytes, granulocytes, hematopoietic stem cells (HSC) and dendritic cells. Granulocytes showed the largest decrease after cryopreservation and thawing (18.2 % vs 3.5 %; p&amp;lt;0.001). The loss of granulocytes results in an increase of relative frequencies of many other immune cell populations including monocytes (35.4 % vs 44.7 %; p=0.018), B cells (5.8 % vs 9.6 %; p=0.006), and HSC (1.0 % vs 1.5 %; p&amp;lt;0.001). We therefore also calculated changes relative to the viable non-granulocyte cells. By doing so, a significant relative increase of cells was observed for HSC (1.2 % vs 1.6 %; p&amp;lt;0.001), whereas monocyte and B cell frequencies changed only marginally. This suggests that HSC are more resilient to freezing than other cell types. When comparing the proportions of 40 other immune cell (sub-) populations relative to their parent population in the gating hierarchy, we found a profound and significant decrease of the relative frequencies for CD16+ myeloid dendritic cells (mDCs, 68 % vs 30 % of all mDCs; p&amp;lt;0.001) and granulocytic myeloid derived suppressor cells (gMDSCs, 2 % vs 1 % of all MDSCs; p&amp;lt;0.001). In an independent set of analyses performed at Roswell Park Comprehensive Cancer Center, Buffalo, comparable results were obtained with a significant increase of HSC, a significant decrease of CD16+ mDCs, and a trend of a decrease of gMDSCs. As CD16+ mDCs may have a role in the development of chronic GVHD after alloHCT, this decrease may be meaningful. In summary, we found that cryopreservation of PBSC allografts resulted in a decreased relative frequency of granulocytes, and CD16+ mDCs, as well as an increased relative frequency of HSCs. The results provide some insight into the impact of cryopreservation on PBSC graft composition and warrant further efforts to explore the potential mechanisms for the differential outcomes observed using fresh vs cryopreserved PBSCs.

Clinical Factors Associated with Catheter-Related VTE in Patients Undergoing Hematopoietic Cell Transplantation

Introduction: In patients undergoing allogeneic hematopoietic cell transplantation (HCT), venous thromboembolism (VTE) is associated with increased morbidity and worse survival. Central venous catheters (CVC) are placed for administration of both stem cell products and other supportive measures. CVC are a common etiology of VTE during HCT. This study examines the associations between patient- and CVC-related variables and the incidence of catheter-related thrombosis (CRT) in patients undergoing allogeneic HCT. Methods: We selected consecutive patients who underwent their first allogeneic HCT from MD Anderson Cancer Center between 2016-2020. The electronic medical records (EMR) of these patients were examined using ICD 9/10 codes, and radiology reports using a natural language processing (NLP) algorithm to look for VTE events. All VTE events were confirmed via manual chart review. Details on the type of CVC, anatomic venous location, laterality, and size were extracted. For this study, CVC was defined as a catheter that extends into the superior vena cava; these catheters were classified as either a peripherally induced central catheter (PICC), non-tunneled CVC, or tunneled CVC. Unadjusted and multivariable Cox proportional hazards models were used to assess the association between patient and transplant factors and time to CRT. Acute graft versus host disease and active infection were included in the models as categorical time varying covariates. Cumulative incidence competing risk model was used to assessed CRT incidence with death as a competing cause. Results: There were 1371 adult patients included in the study. Most patients had non-tunneled CVC as their central access, with the subclavian vein being the most used location (Table 1). A total of 207 patients had VTE during the first year post-HCT, with 153 having isolated CRT and 54 having other VTE (Table 1). The incidence of CRT was 7.7% at 100-day and 11.3% at 1-year, with the incidence rate at a near constant estimate in the first 100 days. The cumulative incidence of DVT/PE with death as a competing risk factor was 1.17% at 100-day and 4.08% at 1-year. In Cox regression models for CRT by 100 days, history of VTE, higher platelet count, acute GVH disease stage 3-4, and infection were statistically associated with time to CRT (Table 2). The type of CVC (non-tunneled CVC and PICC vs. tunneled CVC) was non-significantly associated with increased risk of CRT. Conclusion: In our cohort of patients undergoing allogeneic HCT, the incidence of CRT appeared to be higher than that reported in the literature. Significant risk factors associated with CRT occurred included VTE history, higher pre-transplant platelet count, and development of severe acute GVHD or active infection. While the type of CVC did not reach statistical significance due to the majority of patients receiving non-tunneled CVC as a standard institutional practice, there was a trend of increased CVC in this group of patients. Future multi-center studies that incorporate different types of CVC will further elucidate this potential association with CRT post-transplant.

Incidence, clinical presentation, risk factors, outcomes, and biomarkers in de novo late acute GVHD

AbstractLate acute graft-versus-host disease (GVHD) is defined as de novo acute GVHD presenting beyond 100 days after allogeneic hematopoietic cell transplantation (HCT) without manifestations of chronic GVHD. Data are limited regarding its characteristics, clinical course, and risk factors because of underrecognition and changes in classification. We evaluated 3542 consecutive adult recipients of first HCTs at 24 Mount Sinai Acute GVHD International Consortium (MAGIC) centers between January 2014 and August 2021 to better describe the clinical evolution and outcomes of late acute GVHD. The cumulative incidence of classic acute GVHD that required systemic treatment was 35.2%, and an additional 5.7% of patients required treatment for late acute GVHD. At the onset of symptoms, late acute GVHD was more severe than classic acute GVHD based on both clinical and MAGIC algorithm probability biomarker parameters and showed a lower overall response rate on day 28. Both clinical and biomarker grading at the time of treatment stratified the risk of nonrelapse mortality (NRM) in patients with classic and late acute GVHD, respectively, but long-term NRM and overall survival did not differ between patients with classic and late acute GVHD. Advanced age, female-to-male sex mismatch, and the use of reduced intensity conditioning were associated with the development of late acute GVHD, whereas the use of posttransplant cyclophosphamide–based GVHD prevention was protective mainly because of shifts in GVHD timing. Because overall outcomes were comparable, our findings, although not definitive, suggest that similar treatment strategies, including eligibility for clinical trials, based solely on clinical presentation at onset are appropriate.