Post-transplant Complications Research Articles

Impact of Post-Transplant Cyclophosphamide (PTCY)-Based Prophylaxis in Matched Sibling Donor Allo-HCT for Patients with Myelodysplastic Syndrome: A Study on Behalf of the Chronic Malignancies Working Party of the EBMT

Background Allogeneic hematopoietic cell transplantation (allo-HCT) remains the only potentially curative treatment option for patients with myelodysplastic syndrome (MDS). The use of PTCY for GVHD prevention is becoming increasingly prevalent across donor types/transplant platforms. However, limited studies have evaluated the efficacy and safety of using PTCY in patients with MDS undergoing matched sibling donor (MSD) allo-HCT. We hereby compare the outcomes of PTCY-based versus (vs.) conventional GVHD prophylaxis in a contemporaneous cohort of MDS patients undergoing MSD allo-HCT from the EBMT registry. Methods A total of 404 MDS patients undergoing first MSD peripheral blood allo-HCT between 2014 and 2020 in 52 participating centers, receiving either PTCY or other GvHD prophylaxis, were included. Primary outcomes were overall survival (OS), progression free survival (PFS), GVHD-free/RFS (GRFS), competing risks analyses for relapse (CIR), non-relapse mortality (NRM), and GVHD. The main comparison was PTCY vs. other types of GvHD prevention. Cox regression analyses with predefined covariates were used to obtain adjusted effect estimates of PTCY in post-transplant results.- Results The median age at allo-HCT was 57 years (IQR 49-62), 66 patients (16.3%) received PTCY, 338 (83.7%) received other prophylaxis. As reported in Figure 1, patient characteristics, disease risk, and pre-transplant status were balanced between the two cohorts. The majority of transplant characteristics were also analogous except for the proportion of adults receiving myeloablative regimens, which was higher in the PTCY group (52.3% vs. 38.2%, P=0.047). PTCY was combined with two additional immunosuppressant agents in 66.7% of the cases, with one additional immunosuppressive drug (generally calcineurin inhibitors (CNI)) in 31.8%, and administered as a single agent in only 1 (1.5%) case. Other prophylaxis mainly combined CNI with either mycophenolate mofetil or methotrexate, and in 162 (47.9%) of the cases, anti-thymocyte globulin was also administered. Post-transplant complications and outcomes are shown in Figure 1. Incidences of Day +28 neutrophil (68% vs. 97%, P=0.011) and platelet (71% vs. 92%, P<0.001) engraftment were lower in patients who received PTCY. The day +100 cumulative incidences (CI) of grade II-IV and III-IV aGVHD, and 5-year CI of extensive cGVHD were 32% (21-43%), 18% (9-27%) and 18% (9-28%) for patients who received PTCY, and 25% (20-30%; p=0.3), 13% (10-17%; p=0.4), 31% (26-36%; p=0.09) for those who did not. The 5-year CIs of cardiac and pulmonary toxicities were similar in both groups (23% (6-40%) vs. 19% (12-25%) (p=0.6) and 23% (8-38%) vs. 27% (21-34%) (p=0.6) in PTCY vs others, respectively). At 5-years after allo-HCT, the estimated OS (51% (39-64%) vs. 52% (46-58%), p=0.6), PFS (48% (36-61%) vs. 46% (40-52%), p=0.9), and GRFS (33% (21-45%) vs. 25% (20-30%), p=0.6), were similar between the two study groups. Nevertheless, patients who received PTCY tended to have lower CIR (20% (10-29%) vs. 33% (28-38%) (p=0.06)), but higher NRM rates (32% (20-43%) vs. 21% (16-25%), p=0.09) than the rest. Next, we performed a multivariable analysis (MVA) of OS, PFS, NRM and CIR (Figure 1). The results observed in the MVA confirmed that using PTCY in patients with MDS undergoing MSD allo-HCT resulted in comparable OS (HR 1.23 (0.77-1.97), p=0.4) and RFS (HR 1.13 (0.73-1.77), p=0.6) to conventional prophylaxis. Furthermore, the diagnosis of a high or very high-risk MDS (according to IPSS-R), and the presence of TP53 mutation at diagnosis were independent predictors of worse post-transplant outcomes. In addition, PTCY-based prophylaxis was associated with a higher NRM (HR 1.79 (1.07-2.98), p=0.03) when adjusted by variables known to be clinically relevant for NRM. Conclusion The use of PTCY in adults undergoing MSD allo-HCT for MDS resulted in comparable OS and RFS rates to conventional GVHD prophylaxis. Allo-HCT performed with PTCY was associated with a longer time to engraftment and comparable incidences of clinically relevant aGVHD. Of note, utilization of PTCY was associated with a non-significant trend to a lower incidence of extensive cGVHD. Furthermore, although a non-significant trend to lower rates of relapse were observed in allo-HCTs performed using PTCY, it use was associated with a higher risk for NRM. Further evaluation of PTCY in the MSD setting for MDS is required.

Real-World Analysis of the Underdiagnosis, Clinical Outcomes and Associated Burden of Hematopoietic Stem Cell Transplantation-Associated Thrombotic Microangiopathy (HSCT-TMA) in the United States of America

Background: Thrombotic microangiopathy (TMA) associated with hematopoietic stem cell transplantation (HSCT-TMA) is a serious post-transplant complication. HSCT-TMA is difficult to diagnose due to overlapping symptoms with other conditions and a lack of universally adopted diagnostic criteria. Objectives: This study aimed to assess the incidence and diagnosis of HSCT-TMA in real-world practice across the US, including possible missed diagnoses, alongside clinical outcomes and associated burden of HSCT-TMA. Methodology: This retrospective, observational study investigated the incidence of HSCT-TMA from July 2009-August 2020 using data from the TriNetX US Electronic Medical Record (EMR) database. Patients who underwent autologous or allogenic HSCT procedures and had conditioning regimens recorded were stratified into three cohorts: confirmed TMA, suspected TMA, and non-TMA patients. Confirmed TMA was defined as any individual with at least one recorded hemolytic uremic syndrome (HUS)/TMA diagnosis code within 12 months of HSCT. Suspected TMA included individuals without a recorded HUS/TMA ICD code, but who met the modified published criteria (Cho BS, et al. Transplantation 2010;90:918-26; Jodele S, et al. Transfus Apher Sci 2016;54:181-90) within 12 months of HSCT; published criteria were adapted to fit data available in the TriNetX database. Non-TMA patients did not meet criteria to be included in either of the previous two cohorts. Adult and pediatric patients were analyzed separately. Demographic and clinical characteristics at baseline, clinical outcomes, and all-cause unadjusted healthcare resource utilization within 12 months of HSCT, were assessed. The baseline period was defined as the six months before the index date (inclusive), unless specified; index date was defined as the date a patient had a HSCT procedure code recorded. Statistical comparisons, where conducted, were made against the non-TMA cohort using the Fisher's exact test for categorical variables, the student's t test for means, and the Mann-Whitney U test for medians. Significance was set at the level of p<0.05. Results: In total, 16,809 adult and 901 pediatric patients had an HSCT procedure code and a recorded conditioning regimen. The confirmed TMA group comprised 125 (0.7%) adult and 30 (3.3%) pediatric patients, the suspected TMA group included 3,029 (18.0%) adult and 94 (10.4%) pediatric patients, and the non-TMA group included 13,655 (81.2%) adult and 777 (86.2%) pediatric patients. Baseline demographics were similar across all groups. Mortality within the first year of HSCT was significantly higher in adult patients with confirmed TMA (40.0%) and suspected TMA (30.7%) compared with patients without TMA (13.6%). Mortality was numerically highest in pediatric patients with confirmed TMA (26.7%) followed by suspected TMA (23.4%), and lowest in non-TMA patients (15.8%). Comorbidity impact (based on the Charlson Comorbidity Index) was significantly higher, and HSCT complications significantly more common, in confirmed and suspected TMA patients (Table 1). Clinical outcomes in the first year after HSCT were significantly worse in confirmed and suspected TMA patients than in non-TMA patients (Table 2). All patients with confirmed and suspected TMA had a significantly higher frequency of oxygen/intubation compared with non-TMA patients. Dialysis rates were significantly higher in all patients with confirmed TMA (adults, 26.4%; pediatrics, 20.0%) and adult patients with suspected TMA (6.9%), compared with patients with no TMA (adults, 2.2%; pediatrics, 4.0%); pediatric patients with suspected TMA (8.5%) had numerically higher dialysis rates compared with those without TMA (4.0%). Patients with confirmed and suspected TMA had significantly greater use of targeted therapies and a higher number of total ICU visits, compared with non-TMA patients (Table 2). Conclusions: This study showed that HSCT-TMA is associated with a high mortality and morbidity burden. Furthermore, these results suggest that HSCT-TMA is underdiagnosed in the real-world setting, as patients with suspected TMA had worse outcomes and a higher burden of disease than patients without TMA following HSCT. This study highlights the need for timely diagnosis of this severe complication, as well as novel approaches to treat and manage this vulnerable population.

Venetoclax and Azacitidine for Molecular Relapse during First Line Intensive Chemotherapy in Patients with NPM1 Mutated or Core Binding Factor (CBF) AML. a Study from the Dataml Registry

Introduction: Molecular follow-up (FU) for AML patients (pts) with NPM1 mutation, RUNX1::RUNX1T1 or CBFB::MYH11 fusion transcripts has been established over the last ten years. Real-time quantitative PCR (qPCR) is the gold standard for the evaluation of measurable residual disease (MRD) in pts undergoing intensive chemotherapy (IC). Failure to achieve a deep molecular response is a strong predictive factor of relapse and survival and may guide post remission therapy (Ivey A, NEJM 2016). Moreover, the ELN MRD working party recommended a schedule for molecular FU and recently established a definition of molecular relapse (Heuser M, Blood 2021). However, there is no therapeutic consensus for pts with molecular relapse before overt clinical relapse. Frontline allogeneic hematopoietic cell transplantation (alloHCT), salvage IC or even waiting for morphological relapse in order to screen molecular characteristics of the relapsing disease or propose a clinical trial, may be discussed with pts. Venetoclax with azacitidine (VEN/AZA) was recently approved in unfit AML pts and demonstrated a particular efficacy in NPM1-mutated AML. In this study, we thought to describe the safety and efficacy of VEN/AZA in pts with NPM1 mutated or CBF AML in molecular relapse after first line IC. Methods: Pts of the DATAML registry with the following criteria were included in this study : AML with NPM1 mutation, RUNX1::RUNX1T1 or CBFB::MYH11 transcripts, first line IC, morphological complete remission (CR), no alloHCT in first line, regular monitoring of MRD by qPCR in bone marrow (BM) and/or blood, molecular relapse defined according to ELN2021 guidelines on two successive samples, at least one cycle of VEN/AZA. Pts with molecular relapse followed by morphological relapse before VEN/AZA or those who relapsed after alloHCT were not included. Treatment: First line IC was cytarabine 200 mg/m² d1-7 with idarubicin 9mg/m²/d1-5 or daunorubicin 90mg/m²/d1-3 in pts 18-60y or cytarabine 100 mg/m² d1-7 with idarubicin 8mg/m²/d1-5 and lomustine 200 mg/m²/d1 in pts > 60y. Post remission therapy was intermediate or high dose cytarabine or mini-consolidations according to age and performance status. Midostaurin was added in FLT3-mutated pts. At time of molecular relapse, pts received off label venetoclax 400 mg/d (d1-14, d1-21 or d1-28 according to centers) with no ramp-up and azacitidine 75 mg/m²/d subcutaneously (d1-5, d8-9). Antifungal/antibiotic prophylaxis and G-CSF use were not systematically recommended. Results: Twenty-two pts treated with VEN/AZAfrom 21/09/2020 to30/03/2023 were included. Their characteristics at diagnosis were: female (n= 14), median age 55y (range 27-71), de novo AML (n=21), median WBC (68 giga/L, range 2.32-339.7), NPM1 mutation (n=20), CBFB::MYH11 (n=2), FLT3 mutation (n=13). All pts achieved first CR after one cycle of induction chemotherapy. Pts received a median of three consolidation cycles. All but three pts had negative MRD or low level MRD (LL-MRD) in blood and/or BM at the end of consolidation. The median time between CR1 and molecular relapse was 9.5 months (range, 1-50). The median time between molecular relapse and first VEN/AZA cycle was 51 days. During first cycle of VEN/AZA, 12, 5 and 5 pts received 14, 21 or 28 days venetoclax, respectively; 19 were treated as out-pts, 4 received posaconazole and GCSF was used in 11 pts. 12 and 3 pts had grade 3-4 neutropenia or febrile neutropenia (FN), respectively. Only 3 pts (14%) were hospitalized for FN. The median number of VEN/AZA cycles was 2 (range 1-12). After C1+/-C2, 10 (45%) and 11 pts (55%) had undetectable or LL MRD in blood, respectively (Fig1). 20 pts were bridged to alloHCT in morphological CR after a median of 2 cycles (range, 1-4). Only one pt had a molecular progression before transplantation after 2 cycles. Two pts died, one had a molecular relapse after 7 cycles and progress rapidly to frank relapse, the other one died of post-transplant complication while in CR with undetectable MRD. All other pts remained in CR at date of last news. With a median FU from D1C1 of 13.5 months, median OS wat not reached and 1y-OS was 86% (Fig2). Conclusion: In the setting of molecular relapse, VEN/AZA is safe, prevent overt relapse, and induce a high rate of molecular response before alloHCT. Molecular relapse becomes a major therapeutic challenge. Clinical trial endpoints should include the treatment of molecular relapse as an event for RFS and EFS estimation.

Post-Transplant Cyclophosphamide-Based Prophylaxis and Its Impact on the Immune Reconstitution and the Incidence of Infectious Complications

Introduction PTCY-based prophylaxis is becoming increasingly prevalent across allogeneic hematopoietic cell transplantation (allo-HCT) due to its efficacy on GVHD prevention. However, using PTCY has been associated with delayed engraftment, immune reconstitution, and high infectious complications. Although different studies have investigated how PTCY interacts with infectious risk after allo-HCT, whether the incidences of these complications differ depending on donor type has not been widely investigated. At our institution, PTCY-based prophylaxis has become our institutional prophylaxis irrespectively of the selected donor type. This study explores the incidences of infectious complications and immune cell reconstitution dynamics in patients undergoing allo-HCT with PTCY and according to the donor type selected. Methods This study included the 253 consecutive adults who underwent peripheral blood allo-HCT with PTCY at our institution between 2013 and 2021. Retrospective data was updated in June 2023. All patients received levofloxacin 500mg daily from day +1 until neutrophil engraftment. No patient received letermovir. Cumulative incidences (CI) analyses have been estimated considering death as competing event and reported at day +30, +100, +180, and 1-year. Infection density was calculated by dividing the number of infections of a patient by the observed time period after allo-HCT. Immune reconstitution was evaluated by the measurement of lmmunoglobulin (IgG), CD4+T-cell (CD4) and CD8+T-cells (CD8) levels in alive patients without relapse history. Results The median age was 53 years (range, 18-70 years), with 44 (17.6%) patients older than 65. Acute myeloid leukemia was the most common underlying diagnosis (38%), and 103 (41%) patients received myeloablative conditioning regimens. As reported in Table 1, 120 (47.4%) patients received grafts from HLA-matched donors, 84 (33.2%) from 9/10 HLA mismatched unrelated donors (MMUD) and 49 (19.4%) from haploidentical donors (haplo-HCT). To perform the statistical analysis, the study cohort was divided into 3 groups according to donor type. Baseline characteristics were balanced between these 3 groups, except for the proportion of patients with HCT-CI>3, higher in HLA-matched donor group (p=0.028). As shown in Table 1, 244 (96%) patients engrafted. The median of days to neutrophil and platelet engraftment, and the CIs of clinically relevant acute and chronic GVHD did not differ according to the donor type. Moreover, the duration of the immunosuppression and post-transplant outcomes were similar in all groups. Bacterial bloodstream infections (BSI) were predominantly diagnosed within the first 30 days post allo-HCT, and with a tend to higher incidence in allo-HCT performed from HLA-matched donors (p=0.07). CMV reactivation was the most frequent viral infection in all groups, occurring mostly between days +30 and +100, and with a higher CI in the MMUD group (p=0.033). CMV disease, grade 2-4 BK hemorrhagic cystitis, VHH6 reactivation/disease and fungal infection CIs were not prevalent post-transplant complications generally occurring during the first 100 days after allo-HCT, with comparable CI differences among the 3 groups. The CI of respiratory viral infections increased steadily during the first year after allo-HCT, with similar incidences among the 3 study groups. Infection density analysis showed comparable volume of infections complications in the 3 study groups. As shown in Figure 1, a higher infection density was observed during the first 100 days after allo-HCT (with approximately 1 or 2 number of infections occurring during that time period in most of the patients). After day +100, the number of infections progressively decreased during the post-transplant follow-up. Immune reconstitution was measured in 139 (55%) alive patients. IgG, CD4, and CD8 levels tended to normalize in most patients from day 180 onwards, with median days to normalization of 208, 216, and 203 days, respectively, and with no differences according to donor type. Conclusions Patients undergoing allo-HCT with PTCY-based prophylaxis have a relevant infectious density rate during the peri-engraftment phase with no differences according to donor type. Infectious complications decreased 6 months after allo-HCT, and in parallel with discontinuation of immunosuppression and immune reconstitution with no differences according to donor type.

A Parallel Comparison of the Safety and Efficacy of Allogeneic Hematopoietic Stem Cell Transplantation for Refractory and Relapsed T-ALL/Lbl Patients Who Achieved Complete Remission with CD7 CAR-T Versus Patients Who Achieved First Complete Remission with Chemotherapy before Transplantation

Introduction We have developed a fratricide-resistant CD7 CAR-T cells from bulk T cells transduced with CD7 CAR without gene editing or additional gene transfer, named naturally selected CD7 CAR-T (NS7CAR-T). NS7 CAR-T therapy has shown a robust complete remission (CR) rate in patients with refractory or relapsed (R/R) T-cell acute lymphoblastic leukemia and T-cell lymphoblastic lymphoma (T-ALL/LBL). Nonetheless, the risk of relapse remains a challenge post-CD7 CAR-T therapy alone, suggesting the potential benefits of consolidation allogeneic hematopoietic stem cell transplantation (allo-HSCT). The question remains whether CD7 CAR-T therapy could increase the incidence of post-transplant complications. Here we conduct a parallel study to compare the safety and efficacy of allo-HSCT in R/R T-ALL/LBL patients who achieved CR with NS7 CAR-T therapy vs those who reached first CR (CR1) using chemotherapy prior to transplantation. Methods Between November 2020 and January 2023, a total of 223 consecutive patients with T-ALL/LBL who underwent allo-HSCT at our center were retrospectively analyzed. Patients who met the following criteria were included in this parallel study: 1) underwent the first allo-HSCT in our hospital, 2) achieved CR before transplantation either from NS7CAR-T therapy or CR1 from chemotherapy (Fig. 1). A total of 139 patients met the criteria for analysis and underwent allo-HSCT after achieving CR either from NS7CAR-T therapy (n=43) or chemotherapy (CR1=96). The median patient age at the time of transplantation was 15 years (range: 1-51 years). The median follow-up time was 370 days (2-941 days). CD7 CAR-T patients were from two clinical trials registered at www.clinicaltrials.gov NCT04572308, NCT04916860. Transplant donor types included sibling identical (n=12), haploidentical (n=110), and unrelated donors (n=17). We used total body irradiation (TBI)-based conditioning regimens (n=128) or Busulfan/Melphalan-based regimens (n=11). To prevent graft-versus-host disease (GVHD), we used ATG along with a short-term regimen combining methotrexate, cyclosporine/tacrolimus, and mycophenolate mofetil. Results The characteristics of patients from both groups are detailed in Table 1. The median interval between CD7 CAR-T treatment and transplantation was 59 (39-131) days. Within the CAR-T group, 16 patients had primary refractory disease, 18 had relapsed disease and 9 in minimal residual disease (MRD)-positive status in bone marrow before CD7 CAR-T therapy. Prior to CAR-T therapy, 55.8% (24 patients) had extramedullary lesions. In comparing the CAR-T and chemotherapy CR1 groups, we observed no significant differences in long-term efficacy post-allo-HSCT. The 2-year leukemia-free survival (LFS) rates were 64.9 (95% CI, 49.1-79.2)% and 69.8 (95% CI, 59.0-79.6)% (p=0.340); the 2-year overall survival (OS) rates were 64.1 (95%CI, 48.0-78.6)% and 71.8 (95%CI, 60.5-81.9)% (p=0.107); the 2-year relapse incidence (RI) rates were 9.3 (95%CI, 3.7-23.7)% and 11.5 (95%CI, 6.4-20.7)% (p=0.873); and the 2-year non-relapsed mortality (NRM) rates were 28.3 (95% CI, 16.9-47.4)% and 21.6 (95% CI, 13.9-33.4)% (p=0.244), for the CD7 CAR-T and non-CAR-T groups, respectively. The incidence of all grades of acute GVHD (aGVHD) 37.2 (95%CI, 25.2-54.9)% vs. 42.1 (95%CI, 33.3-53.3)% did not significantly differ between the CAR-T and non-CAR-T groups. A trend toward an increased rate but no P significance was observed in Grade 3-4 aGVHD incidence of 20.93 (95%CI, 11.7-37.4)% vs. 9.5 (95%CI, 5.1-17.6)% (p=0.139). One-year incidences of moderate to severe chronic GVHD (cGVHD) were 12.2 (95%CI, 5.4-28.0)% and 18.0 (95%CI, 11.5-28.0)% (p=0.357) in the CD7CAR-T and non-CAR-T groups, respectively (Table 2). No statistically significant differences were detected in the occurrences of transplant-associated thrombotic microangiopathy (TA-TMA), CMV, EBV, and HHV-6 infections between the two groups. Upon analyzing, we found that r/r patients who received allo-HSCT after achieving remission with NS7 CAR-T had a similar OS to CR1 patients (Fig. 2). Conclusions Our parallel study showed that T-ALL/LBL patients, who achieved CR via CD7 CAR-T therapy followed by a consolidation allo-HSCT, had similar favorable OS and LFS compared to patients who underwent allo-HSCT in the CR1 state induced by chemotherapy. This was achieved without increasing the incidence of GVHD, infections, or TA-TMA.

Enhancement of Mitochondrial Membrane Potential and Pro-Survival Pathways with Azole Compound C7 Resulting in Expansion of Hematopoietic Stem and Progenitor Cells

Ex-vivo expansion of hematopoietic stem & progenitor cells (HSPC) could improve hematopoietic recovery and reduce post-transplant complications, especially for umbilical cord blood (UCB) grafts where limited total cell numbers result in delayed engraftment. Freshly-thawed UCB mononucleated cells (MNCs) or purified CD34 + cells were cultured in animal component free medium supplemented with C7 and a basal cytokine cocktail. The effects of the expansion protocol were measured with phenotypic, in-vitro, and in-vivo functional assays. A range of molecular techniques were also performed to elucidate the mechanisms of action of C7. In previous studies, expansion cultures initiated with UCB-MNCs and supplemented with C7 resulted in significant expansions of UCB HSPC over 11 days and these grafts demonstrated elevated and sustained multi-lineage engraftment of human cells in primary NSG mice (Bari et al., 2018). In UCB-CD34+ enriched cultures, the addition of C7 to a basal cytokine cocktail also boosted absolute CD45+CD34(BR)+CD38-CD45RA- progenitor expansion by 283±29.4 fold over 11 days which was 1.86±0.12 fold higher than control cultures (p<0.001; n=6). Furthermore, C7 induced significant expansion of primitive HSPC in UCB-MNC defined by phenotype CD45+CD34(BR)+CD38-CD45RA-CD90+CD49f+ by more than 633±8.5 fold, which is 7.5±0.16 fold higher compared to control cultures (p<0.01; n=3). The addition of C7 to CD34+ cells from mobilized peripheral blood (PB) and bone marrow (BM) also resulted in a significant expansion of HSPCs (p<0.05; n=3) (Fig 1A). When expanded UCB-CD34+ were engrafted in NSG mice, NSG PB analysis at week 3 and week 28 post-transplantation showed significantly higher (p<0.01) human CD45+ cell engraftment in C7 expanded graft (16.4%±2.6) than cytokine expanded graft (7.8%±0.9). NSG BM analysis at week 31 also exhibited similar trends for human CD45+ cell engraftment in C7 expanded grafts with multilineage reconstitution (p<0.01; n=6). Significantly enhanced CD45+ cell viability (p<0.01; n=3) was observed in C7 cultures compared to control cultures. Mitochondrial health was also improved as confirmed by lower mitochondrial superoxides and higher mitochondrial membrane potential in C7-cultured UCB-MNCs (p<0.05; n=3) that is reflective of reduced reactive oxygen species (ROS) (Fig 1B). As C7 is a chemical analogue of a p38 inhibitor (SB203580), p-p38 (T180/Y182) was significantly reduced in C7-expanded CD34+ culture compared to controls. Significant increases in HIF-1α in C7 expanded CD34+ cells were also observed, potentially indicative of a hypoxic state induced by C7 to benefit HSPC together with reduced levels of ROS. Kinase inhibition profiling studies on C7 identified CK1δ, a kinase involved in Wnt and p53 signalling pathways, as one of the activation targets directly activated by C7. CK1δ was boosted in C7-expanded cells and this was further validated with western blots on C7 expanded pooled CD34+. CK1δ plays a putative role in p53 activation which is stipulated to promote HSC quiescence favouring long-term maintenance of HSPCs. Western blot analysis also revealed that p53 and BCL-2 were increased with C7 expanded CD34+. GSK3β was also boosted in C7 expanded pooled CD34+ cultures possibly as a result of CK1δ signalling leading to increased proliferation via the Wnt signalling pathway. Multiple safety studies were conducted on C7 to ensure its safety in clinical applications. This included the BIOMAP phenotypic safety and toxicology tests on human primary cells, AMES test and fluctuation assays for bacteria and SAFETYscan47 TM In Vitro Pharmacological Profiling for biochemical safety, all of which were negative for any cytotoxicity or off-targets associated with acute toxicity. No changes were detected in cytogenetics and fluorescence in situ hybridization with UCB-MNC for major leukemia-related genetics as well when they were cultured with C7. As a small molecule capable of significant HSPC expansion from both UCB and PB sources, C7 is promising for the future of HSPC transplantation. The mechanism behind C7 is likely to be a multi-pronged one with p38 inhibition, increase in HIF-1α, CK1δ activation, improved mitochondrial health, and induction of pro-survival pathways for expanding HSPC populations.

SMC4 Loss of Function Is a New Cause of Inherited Bone Marrow Failure

Inherited bone marrow failure syndromes (IBMFS) are a rare, heterogenous group of syndromes that are characterized by cytopenias, bone marrow hypocellularity, and in many cases an increased risk of transformation to myeloid malignancy. Presentation with severe pancytopenias at birth is reported but occurs very rarely, and more often neonatal pancytopenia is attributed to congenital and acquired infections or other acquired causes. We present the case of a preterm neonate with pancytopenia from birth and bone marrow failure of no known infectious, other acquired, or genetic etiology. Antenatal findings were notable for non-immune hydrops fetalis at 30 weeks of gestation prompting delivery. The initial laboratory evaluation revealed a normocytic, reticulocytopenic, severe anemia; leukopenia with an absolute neutrophil count of 500; and severe thrombocytopenia. Viral testing, including parvovirus, rubella, herpes simplex virus, cytomegalovirus, adenovirus, and enterovirus, was negative. Additional testing, including a chromosomal microarray, mitochondrial genome sequencing, chromosome stress testing, neonatal alloimmune thrombocytopenia panel, and telomere length analysis, was non-diagnostic. Bone marrow biopsy showed a remarkably hypoplastic marrow without evidence of dysplasia or cytogenetic abnormalities. The proband underwent matched unrelated donor hematopoietic stem cell transplant, and died approximately one month later from post-transplantation complications including hepatic veno-occlusive disease, thrombotic microangiopathy, CNS and pulmonary hemorrhages, pseudomonal sepsis, and multi-organ dysfunction. Autopsy was significant for microscopic pancreatic atrophy with lipomatous hypertrophy and osteopenia. The proband and parents underwent clinical exome testing which was non-diagnostic and then consented to research reanalysis of the exome data. Research reanalysis identified the infant was compound heterozygous for predicted deleterious variants in the Structural Maintenance of Chromosomes 4 gene (SMC4), inherited in trans from each unaffected parent (c.2478_2479ins10 splice site variant predicted to alter splicing and c.T591G; p.Y197X). Germline variants in SMC4 have not been reported as a cause of human disease; however, somatic variants are observed in several cancers including in acute myeloid leukemia (AML). SMC4 is a highly conserved protein that forms a heterodimer with Structural Maintenance of Chromosomes 2 (SMC2) in the condensin II protein complex. This complex is important for chromosome condensation, cell division, and DNA repair. Within hematopoietic tissue, SMC4 expression is higher in hematopoietic stem and progenitor cells when compared with mature lineage cells. Given the predicted loss of function from both SMC4 variants, we performed RNAseq on proband and control fibroblasts. This showed a roughly 10-fold decrease in total SMC4 transcript levels (Figure 1A). A significant proportion of the transcript present was comprised of an aberrantly spliced transcript characterized by exon 15 skipping. We therefore hypothesized that loss of SMC4 expression leads to a cell intrinsic defect in hematopoiesis. To test this hypothesis, we used CRISPR-Cas9 gene editing to generate knockout of SMC4 in human cord blood CD34+ hematopoietic stem/progenitor cells (HSPCs) before culturing cells in an all-colony forming unit (CFU) assay. Using two independent small guide RNAs, we were able to achieve approximately 80% knock-down. After 14 days in culture, we observed a striking decrease in CFUs when compared with controls, though the composition of colony types was relatively unchanged (Figure 1B). Using next-generation sequencing, we observed a significant decrease in remaining SMC4 genome edits at the end of the culture period, suggesting a relative disadvantage of SMC4-edited cells for survival and/or proliferation. In summary, we describe a preterm infant with congenital bone marrow failure without an identifiable cause and link this phenotype to biallelic loss-of-function variants in SMC4. This is the first study identifying SMC4 as a novel gene that causes inherited bone marrow failure, and further experiments are underway to validate this finding.

Kidney allograft torsion, a rare post kidney transplantation complication: a case report

Kidney allograft torsion, a rare post kidney transplantation complication: a case report

Impact of donor hepatic duct bifurcation location and angle on posttransplant biliary complications in recipients following living donor liver transplantation

Impact of donor hepatic duct bifurcation location and angle on posttransplant biliary complications in recipients following living donor liver transplantation

Towards Allograft Longevity: Leveraging Omics Technologies to Improve Heart Transplant Outcomes.

Heart transplantation (HT) remains the optimal therapy for patients living with end-stage heart disease. Despite recent improvements in peri-transplant management, the median survival after HT has remained relatively static, and complications of HT, including infection, rejection, and allograft dysfunction, continue to impact quality of life and long-term survival. Omics technologies are becoming increasingly accessible and can identify novel biomarkers for, and reveal the underlying biology of, several disease states. While some technologies, such as gene expression profiling (GEP) and donor-derived cell-free DNA (dd-cfDNA), are routinely used in the clinical care of HT recipients, a number of emerging platforms, including pharmacogenomics, proteomics, and metabolomics, hold great potential for identifying biomarkers to aid in the diagnosis and management of post-transplant complications. Omics-based assays can improve patient and allograft longevity by facilitating a personalized and precision approach to post-HT care. The following article is a contemporary review of the current and future opportunities to leverage omics technologies, including genomics, transcriptomics, proteomics, and metabolomics in the field of HT.

Effects of Preservation of Donor Liver Gastroduodenal Artery on Post-Transplant Biliary Complications in 187 Liver Transplant Recipients: A Retrospective Study.

BACKGROUND This retrospective study aimed to evaluate the effects of preservation of the donor liver gastroduodenal artery on post-transplant biliary complications in 187 liver transplant recipients. MATERIAL AND METHODS The clinical data of 187 liver transplantation recipients were retrospectively analyzed. Recipients were divided into conventional and modified groups. The technical point of the modified group is to preserve at least 2 cm of the distal gastroduodenal artery, and pay special attention to preserve the superior pancreaticoduodenal artery to ensure the distal blood supply to the common bile duct. RESULTS The modified group had significantly shorter operative time (7.17 vs 7.98) h (P<0.001) and less intraoperative blood loss (2715.40 vs 3434.93) ml (P=0.003) than the conventional group. The incidence of postoperative biliary complications (including anastomotic biliary leakage, ischemic bile duct stenosis, and anastomotic bile duct stenosis) in the modified group (4/114, 4.1%) was significantly lower (15/73, 20.5%) (P<0.001). There was no significant difference in the intraoperative cold and warm ischemia time and postoperative hospital stay length between the 2 groups. In addition, there was no significant difference in the effect of cardiac-death and brain-death sources on perioperative biliary complications, while the peak postoperative transaminase and total bilirubin were higher in patients receiving the donor liver of cardiac death (P<0.05). CONCLUSIONS Preserving the integrity of the donor gastroduodenal artery and surrounding tissue is beneficial to protect the blood supply of the extrahepatic bile duct, and can reduce the incidence of biliary complications.

A Retrospective Analysis of the 1-Year Graft Survival Rate in Indonesian Renal Transplant Recipients With Multiple Renal Arteries

Renal transplantation is the preferred treatment for end-stage renal disease because of its association with improved survival and quality of life. The debate over multiple renal arteries (MRA) vs a single renal artery regarding kidney function, posttransplant complications, and graft and patient survival remains ongoing. Our goal was to determine the 1-year graft survival rate among renal transplant recipients with MRA at Cipto Mangunkusumo Hospital in Jakarta. A retrospective study was conducted between January 2012 and December 2020, including all kidney transplant candidates with MRA. Data on graft survival, patient demographics, previous renal transplantation, duration of hemodialysis, and delayed graft function were collected and analyzed using SPSS 24. Kaplan-Meier plots and Cox regression analyses were used to determine risk factors for 1-year survival. Among 752 renal transplant recipients, 104 cases had MRA. The majority were men (71.5%), and the median age of recipients was 47 years. One-year graft survival was observed in 96% of cases, whereas patient survival was 97.7%. No significant difference was found in graft survival based on the number of arteries (single renal artery vs MRA), length of hemodialysis, or previous renal transplantation. However, delayed graft function was significantly associated with graft survival. This study highlights that 1-year graft survival in renal transplant recipients with MRA is not significantly affected by the length of hemodialysis before surgery or previous renal transplantation.

Inflammasome pathway in kidney transplantation.

Kidney transplantation is the best available renal replacement therapy for patients with end-stage kidney disease and is associated with better quality of life and patient survival compared with dialysis. However, despite the significant technical and pharmaceutical advances in this field, kidney transplant recipients are still characterized by reduced long-term graft survival. In fact, almost half of the patients lose their allograft after 15-20 years. Most of the conditions leading to graft loss are triggered by the activation of a large immune-inflammatory machinery. In this context, several inflammatory markers have been identified, and the deregulation of the inflammasome (NLRP3, NLRP1, NLRC4, AIM2), a multiprotein complex activated by either whole pathogens (including fungi, bacteria, and viruses) or host-derived molecules, seems to play a pivotal pathogenetic role. However, the biological mechanisms leading to inflammasome activation in patients developing post-transplant complications (including, ischemia-reperfusion injury, rejections, infections) are still largely unrecognized, and only a few research reports, reviewed in this manuscript, have addressed the association between abnormal activation of this pathway and the onset/development of major clinical effects. Finally, the regulation of the inflammasome machinery could represent in future a valuable therapeutic target in kidney transplantation.

Pre-Emptive Use of Rituximab in Epstein-Barr Virus Reactivation: Incidence, Predictive Factors, Monitoring, and Outcomes.

Post-transplant lymphoproliferative disease (PTLD) is a fatal complication of hematopoietic cell transplantation (HCT) associated with the Epstein-Barr virus (EBV). Multiple factors such as transplant type, graft-versus-host disease (GVHD), human leukocyte antigens (HLA) mismatch, patient age, and T-lymphocyte-depleting treatments increase the risk of PTLD. EBV reactivation in hematopoietic cell transplant recipients is monitored through periodic quantitative polymerase chain reaction (Q-PCR) tests. However, substantial uncertainty persists regarding the clinically significant EBV levels for these patients. Guidelines recommend initiating EBV monitoring no later than four weeks post-HCT and conducting it weekly. Pre-emptive therapies, such as the reduction of immunosuppressive therapy and the administration of rituximab to treat EBV viral loads are also suggested. In this study, we investigated the occurrence of EBV-PTLD in 546 HCT recipients, focusing on the clinical manifestations and risk factors associated with the disease. We managed to identify 67,150 viral genomic copies/mL as the cutoff point for predicting PTLD, with 80% sensitivity and specificity. Among our cohort, only 1% of the patients presented PTLD. Anti-thymocyte globulin (ATG) and GVHD were independently associated with lower survival rates and higher treatment-related mortality. According to our findings, prophylactic measures including regular monitoring, pre-emptive therapy, and supportive treatment against infections can be effective in preventing EBV-related complications. This study also recommends conducting EBV monitoring at regular intervals, initiating pre-emptive therapy when viral load increases, and identifying factors that increase the risk of PTLD. Our study stresses the importance of frequent and careful follow-ups of post-transplant complications and early intervention in order to improve survival rates and reduce mortality.

Pediatric Transplant Interventions

The field of pediatric organ transplantation has grown significantly in recent decades, with interventional radiology (IR) playing an essential role in managing pre- and post-transplant complications. Pediatric transplant patients face unique challenges compared to adults, including donor-recipient size mismatch, and complications of a growing child with changing physiology. Interventional radiologists play a major role in pediatric renal and liver transplant. IR interventions begin early in the child's pre-transplant journey, with diagnostic procedures such as biopsies, angiograms, and cholangiograms. These procedures are essential for understanding the etiology of organ failure and identifying potential transplant candidates. Minimally invasive therapeutic procedures may serve as bridges to transplant and may include vascular access optimization for hemodialysis, TIPS shunt creation, and tumor embolization or ablation. After transplant, image-guided biopsies for the surveillance of graft rejection and treatment of vascular or luminal stenoses, pseudoaneurysms, and anastomotic leaks can maintain the function and longevity of the transplant organ. Careful consideration must be given to patient size and evolving anatomy, radiation exposure, and the need for deeper sedation for pediatric patients. Despite these challenges, the integration of IR in pediatric transplant care has proven beneficial, offering minimally invasive alternatives to surgery, faster recovery times, and improved outcomes.

Impact of the Addition of Daratumumab to the Standard Bortezomib-Thalidomide-Dexamethasone Regimen on Hematopoietic Stem Cell Mobilization and Collection, Post-Transplant Engraftment and Infectious Complications: A Case-Control Multicentre Real-Life Analysis

Background The pivotal clinical trial CASSIOPEIA established the quadruplet Daratumumab-Bortezomib-Thalidomide-Dexamethasone (Dara-VTD) as superior with regards to the standard Bortezomib-Thalidomide-Dexamethasone (VTD) regimen as induction therapy in newly diagnosed transplant-eligible (NDTE) multiple myeloma (MM) patients. As a matter of facts, Dara-VTD is currently the approved induction scheme in NDTE MM patients in Italy. Previous reports showed that adding Daratumumab in induction therapy patients yielded to a higher number of poor mobilizers, with a lower median number of collected hematopoietic stem cells (HSC). However, these reports included different types of induction therapies, merging patients on and off clinical trials, and real-life data focusing exclusively on Dara-VTD is lacking. We report our experience on the impact of Dara-VTD on HSC mobilization and collection, with a retrospective comparison with a cohort of patients treated with VTD and we also provided data concerning post-transplant engraftment and infectious complications. Methods From January 2022 to June 2023, 109 NDTE MM patients from 5 Haematology Institutions received Dara-VTD treatment induction according to the approved doses and schedule. The control group consisted of 116 age-matched patients treated with VTD in the years 2015-2016. Mobilizing therapy consisted of cyclophosphamide 1-3 gr/sqm followed by granulocyte colony-stimulating factor (G-CSF) 10 mcg/kg starting the 5th day thereafter, with HSC harvest planned on the 11th day. Patients received only G-CSF 10 mcg/kg if they were older than 70 years or had renal impairment (i.e., eGFR &amp;lt; 50 ml/min). Poor mobilizer was defined as having less than 20 CD34+/µL in peripheral blood on the 11th day after cyclophosphamide and G-CSF or on the 4th day of G-CSF alone administration. In that case, plerixafor was added at the standard dose of 0.24 mg/kg. Results In the Dara-VTD group, 96/109 patients received cyclophosphamide and G-CSF; among them, 3 patients had failed a previous G-CSF mobilizing therapy, even with the addition of plerixafor. Thirteen patients received G-CSF only. In the VTD group, all patients had received cyclophosphamide and G-CSF. Pre-harvest median number of CD34+/mL in the Dara-VTD group was 26 (range 0.8-279) vs 76 (range 20-294) in the VTD group and the incidence of poor mobilizing patients was 41.7% vs 5.9%, respectively (OR 0.3, 95% CI 0.16-0.54, P &amp;lt; 0.0001). Baseline disease characteristic did not have an impact on poor mobilizing events. On the contrary, patients who developed hematologic toxicity during induction turned out to be poor mobilizers (OR 3.5, 95% IC 1.36-9.59, p= 0.011). Plerixafor was used in 54/109 patients in the Dara-VTD group and in 16/116 patients of the VTD group. Two patients failed HSC mobilization both with G-CSF and cyclophosphamide and G-CSF. All patients that received G-CSF only resulted in poor mobilizers and required plerixafor before HSC harvest; therefore, cyclophosphamide showed to be superior with regards to G-CSF as mobilizing therapy (p= 0.011). The median number of collected HSC was significantly lower in the Dara-VTD group vs VTD group: 5.17 x 10^6/Kg (IQR 3.9-5.47) vs 8.7 x 10^6/kg (IQR 6.35-11.15), respectively (p &amp;lt; 0.0001). 33% of patients in Dara-VTD group collected at least 6 x 10^6 CD34+/Kg). Median time to neutrophils and platelets engraftment were different between the two groups (13 and 11 days, respectively, P &amp;lt; 0.0001), but we did not observe any difference in terms of infection incidence. Notably, post-transplant infections incidence in Dara-VTD group was 43%. Although the second transplant was planned for 36 patients treated with Dara-VTD, it was performed in 10 patients only, mainly because of insufficient HSC harvest. Conclusions Our experience with Dara-VTD confirms an increased number of poor mobilizers, a higher need for the use of plerixafor and a lower number of collected HSC. We observed a slightly lower engraftment in Dara-VTD group, probably because of a lower number of infused HSC. The lower number of collected HSC hampers the possibility of a double transplant.

Exploring Clonal Hematopoiesis in Chronic Graft Versus Host Disease Patients: A Comprehensive Study

Introduction Clonal hematopoiesis (CH) is a prevalent condition characterized by the presence of genetic mutations in hematopoietic cells, without being associated with any overt hematological malignancy. Emerging evidence has linked CH to various health complications, potentially contributing to higher morbidity rates in cancer survivors and individuals with chronic inflammatory diseases. Increased inflammation has been identified as a consequence of CH-related mutations, which may underlie these risks. Chronic graft versus host disease (cGVHD), debilitating complication of allogeneic hematopoietic stem cell transplantation (allo-HSCT), is a multisystem inflammatory disease. However, to date, the relationship between CH and cGVHD remains poorly understood. This study aims to investigates the potential role of CH in increasing the risk of developing cGVHD. Methods Research was conducted on patients who met the following inclusion criteria; (1) adult (age ≥ 18 years) acute myeloid leukemia (AML) patients who had previously consented to blood banking at a human resources bank and signed a residual specimen research agreement (IRB: H-2202-100-1302); (2) received allo-HSCT between Jul 2013 and Oct 2020; (3) experienced cGVHD of any NIH severity; (4) had peripheral blood sample taken after the occurrence of cGVHD but without relapse at that time, evidenced by &amp;gt;95% donor chimerism. The sequencing of 24 CH-related genes reported to date was performed at a sequence depth of ≥1000X, and the results were reported with a sensitivity of 99.9% and an accuracy of 99.9%. Analysis was conducted on patients with Variant Allele Frequency (VAF) ranging from 2.0% to less than 30.0%, classifying them as CH positive. Result A total of 134 patients who met the inclusion criteria were included in the analysis. The mean age at matched sibling donors (MSD) (n=41, 30.6%), unrelated donors (UD) (n=38, 28.4%) and haplo-identical donors (HID) transplants (n=55, 41.0%) was 48, 45 and 43 years for recipients, respectively, with no statistically significant difference (p=0.220). However, there was a significant difference in the mean age of donors, with 45, 32 and 32 years for MSD, UD and HID transplants, respectively (p&amp;lt;0.001). Among the cGVHD patients, 11.9% (16/134) tested positive for CH. The majority of these CH+ patients had a DNMT3A mutation (11) followed by TET2 (2), ASXL1 (1) and PPM1D (1). Between the CH- and CH+ groups, there were no statistically significant differences in age (both recipient and donor), gender, and clinical outcomes including relapse and death. A trend towards a higher incidence of CH+ was observed in patients receiving HID transplants, with 3/41 (7.3%) for MSD, 3/38 (7.9%) for UD, and 10/55 (18.2%) for HID, although this difference was not statistically significant (p=0.177). In addition, we could not observe the differential impact of donor age on the incidence of CH+ after allo-HSCT. The distribution of CH was further analyzed based on clinical outcomes, dividing patients into severe cGVHD and non-severe cGVHD groups. The results showed that patients with a mutation in the TET2 gene, which contributes to CH, accounted for 6.9% (2/29) of the total patients in the severe cGVHD group, while it was 0% (0/105) in the non-severe cGVHD group. Next, we compared CH data from cGVHD patients to a cohort of 5205 healthy individuals in Korea, where a CH positivity rate of 7.9% was observed. We found a statistically significant increase in the odds ratio for CH positivity in the overall cGVHD population after adjusting for age. The highest detection of CH, including the DNMT3A gene, was observed when adjusting for recipient age (odds ratio of CH 2.41[1.39-4.19], p= 0.002) and when adjusting for donor age (odds ratio of CH 3.79[2.10-6.83], p= 0.001). Conclusion In this study, we found that 11.9% of cGVHD AML patients who underwent allo-HSCT tested positive for CH, with DNMT3A mutation being the most common. There was a trend towards a higher incidence of CH+ in HID transplant although it was not statistically significant. Compared to healthy individuals, cGVHD patients had a significant higher risk for CH positivity, particularly when adjusting for age. For the deeper understanding of CH's role in post-transplant complications, further analysis with incorporating the data regarding baseline genetic information from recipients and donors and non-cGVHD patients after allo-HSCT would be warranted.

Treatment of Refractory Adenovirus (ADV) Infections Using Adv-Specific Cytotoxic T-Lymphocytes (CTLs) in Children, Adolescents and Young Adults (CAYA) Post Allogeneic Hematopoietic Stem Cell Transplantation (AlloHSCT), Solid Organ Transplantation (SOT), or with Primary Immunodeficiency (PID)

Background: AlloHSCT induces long-term, cure in CAYA with malignant and non-malignant disorders, including those with primary immunodeficiencies (PID). However, post-transplant complications secondary to immunosuppression and slow or delayed immune reconstitution remains a cause of morbidity and mortality amongst AlloHSCT recipients (Satwani/Cairo, BBMT, 2009). Major complications include refractory viral infections, most importantly adenovirus (ADV), which is secondary to absent or decreased adenovirus specific T-cell immunity which occurs due to delayed immune reconstitution and/or continued immunosuppression (George/Cairo, BJH, 2012). The use of virus-specific (vs) CTLs in immunocompromised patients offer an opportunity to restore temporary virus specific immunity. From the Viral Cytotoxic T-Lymphocyte Consortium (VIRCTLC), we present safety and efficacy results on immune compromised, AlloHSCT, or SOT patients treated with familial ADV specific CTLs. Objective: Determine the safety and efficacy of familial ADV specific CTLs for the treatment of refractory systemic ADV infections. Design/Methods: Patient were deemed eligible if they had a history of AlloHSCT, SOT, or PID and had evidence of ADV infections refractory to anti-viral agents. Refractory ADV infection was defined by increasing serum RT-PCR DNA (by 1 log) after 7 days or persistent quantitative RT-PCR DNA copies after 14 days of appropriate anti-viral therapy, and/or known resistance/intolerance to anti-viral agents. Related donors were required to be matched ≥3 HLA (A, B, or DRB1) loci and have an adequate T-cell response to viral specific MACS ADV PepTivators®. We chose a direct selection method to facilitate more rapid generation of cellular products in a point of care setting (and with 14 hrs eligibility determination). Peripheral blood mononuclear cells were collected from eligible family donors using non-mobilized apheresis. vsCTLs were isolated using the CliniMACS ® Prodigy following stimulation with viral specific MACS® GMP PepTivator® AdV5 Hexon, generously provided by Miltenyi Biotec®. ADV specific CTLs were enriched using a Cytokine Capture System (CCS). CD4+ and CD8+ vsCTLs were quantified by flow cytometry (Feuchtinger et al, Blood, 2010). The target cell dose was 0.5x10 4 CD3+ cells/kg (recipient weight) for haploidentical related donors and 2.5x10 4 CD3+ cells/kg for matched related donors. Repeated doses were permitted every 2 weeks to a maximum of doses in the absence of a complete response (CR) and adverse events. The following were used to define response: CR - undetected ADV PCR, partial response (PR) - at least one log decrease from baseline, progressive disease (PD) - at least one log increase from baseline, and patients with stable disease. Results: Fifteen patients were enrolled: 10 females and 5 males; aged 1-19 years. All patients were post-AlloHSCT. All vsCTL donors were haploidentical: 8 were the original HSCT donors and 7 were third party donors (5 maternal, 2 paternal). The mean number of ADV CTL infusions was 3.7 (range: 1-16). One patient with underlying aplastic anemia had progressive disease complicated by increased adenoviral load despite 5 infusions of vsCTLs. Patient received FDA approval for additional CTLs, totaling 16 doses. Thirteen patients achieved CR as defined and 2 achieved PR. The overall response (OR) was 100% and the CR was 88%. The average time to OR was 33 days (range 6-112 days) and time to CR was 34 days (range 6-112 days). Day 100 and 365 overall survival (OS) post-HSCT was 86.1% (CI95: 49.4-95.7) and 70.5% (CI95: 38.9-87.8), respectively (Figure 1). For patients who achieved CR, the Day 100 OS post AlloHSCT was 83.9% (CI95: 55.0-94.3) and Day 365 post AlloHSCT was 74.6% (CI95: 39.8-91.1). Day 100 and 365 probability of ADV related mortality was 0% (Figure 2). One patient developed acute grade 2 skin GVHD possibly related to infusion, which resolved. Conclusion: Our preliminary data demonstrate that haploidentical ADV specific CTLs manufactured by direct selections using the CCS with the CliniMACS® Prodigy and ADV specific peptivators are safe, well-tolerated, and efficacious in patients with refractory/persistent ADV infections after AlloHSCT. Manufacturing is rapid, reproducible, and effective. Accrual is ongoing. This research is supported by FDA RO1006301A1.

Clonal Hematopoiesis Is Common in Long-Term Survivors of Pediatric Hematopoietic Cell Transplantation, Including Umbilical Cord Blood Transplantation

Background 1. Approximately 20.000 to 200.000 hematopoietic stem and progenitor cells (HSPCs) contribute to steady-state adult hematopoiesis. During ageing, the overall diversity of the HSPC pool decreases, which is in part driven by the selective expansion of HSPC clones with driver mutations, a process called clonal hematopoiesis (CH). CH is an age-related condition that predisposes to hematologic malignancy, cardiovascular disease, and all-cause mortality. Hematopoietic stem cell transplantation (HCT) recipients are at increased risk of CH, but the mechanisms driving the emergence and expansion of CH clones are largely unknown. Furthermore, the prevalence of CH in pediatric HCT recipients, in whom the long-term consequences of CH are particularly relevant, remains to be defined. Aim To determine the prevalence and risk factors of CH in long-term survivors of HCT at pediatric age. Methods We included survivors of HCT at pediatric age, with a minimum survival of 5 years after HCT. CH was assessed by targeted, error-corrected sequencing of mutations in 27 cancer driver genes in whole blood, at a variant allele frequency detection threshold of 1%. HSC age was calculated by the sum of the age of the donor and the interval after HCT. In case the age of a donor was unknown (n=53), the median age for donors of the same donor relation were used (i.e., 12.6 years for sibling donors and 28.7 for matched unrelated donors). Clinical characteristics were compared using the Wilcoxon signed ranked test for continuous variables and Chi-squared or Fisher's exact test for categorical variables. Results Here, we report the interim results of the first 120 HCT survivors in this study. The median age of the survivors was 20.4 years (range 6.7-51.8), and the median interval after HCT was 11.8 years (range 5.2-38.2). Indications for HCT were hemato-oncology (n=95), bone marrow failure (n=22), or immune deficiency (n=3). The median calculated age of the HSCs was 31 years (range 5.2-61.8). CH was present in 13.3% of survivors (n=16). Mutated genes were DNMT3A (n=15), TET2 (n=4) and MPL (n=1), with three individuals having more than one driver mutation. The median variant allele frequency of the CH clones was 2.2%, but allele frequencies up to 30% were found. No differences were observed in recipient age or interval after HCT between individuals with or without CH (Figure 1A). However, the age of the HSCs was significantly higher in individuals with CH compared to those without (38.6 versus 26.3 years, p = 0.01, Figure 1B). Surprisingly, we detected CH in two recipients of umbilical cord blood grafts, at an interval of 11 and 15 years after HCT. Conclusion Clonal hematopoiesis is common in long-term survivors of pediatric HCT. After HCT, the prevalence of CH is related to the age of the transplanted HSCs, rather than the age of the survivor. The presence of CH in cord blood HSCs within two decades after HCT suggests that HCT-related factors may drive the de novo emergence and/or outgrowth of donor-derived CH. Ongoing research is aimed at investigating how factors such as stem cell source and post-transplant complications affect clonal expansion after HCT. Furthermore, we are investigating the prevalence of CH in an age-matched control cohort using the same detection pipeline, enabling direct comparison of the prevalence of CH in HCT survivors compared to the general population.

Kidney transplant to vesicostomy: A safe strategy for children with end stage renal disease and lower urinary tract anomalies

Resolution of underlying urinary tract anomalies prior to kidney transplantation in patients with end stage renal disease (ESRD) secondary to uropathy, has been historically supported under the argument that this would help prevent infectious complications and graft loss. We propose to perform earlier kidney transplantation with a transient vesicostomy, deferring resolution of the uropathy to the post-transplantation period. The aim of this study was to evaluate the outcomes of kidney transplantation in children with a vesicostomy. A retrospective, multicenter study was performed including all patients under 18 years of age who underwent kidney transplantation with a vesicostomy, between January 2005 and December 2020 and had at least one year of follow up. Data related with the indication and timing of vesicostomy, time until transplantation, post-transplantation complications, urinary tract infections (UTI) and graft survival rate were collected. Of the 758 transplantations performed in the study period, 16 patients met the inclusion criteria. Mean age at transplantation was 58 months (range 20-151), and mean weight was 13.5Kg (range 8.4-20). Mean time from vesicostomy to kidney transplantation was 30 months (range 0-70). There were 2 (12.5%) ureteral complications that required reoperation. Eighteen episodes of UTI were identified in 8 patients (50%), accounting for 0.4 UTIs per patient-year of follow-up. UTIs did not lead to graft loss in any of the cases. Urinary tract reconstruction was performed in 5 patients (31.3%) at an interval of 1-91 months post-transplantation. After a mean follow-up of 44.8 months (range 13-200) from transplantation, patients with vesicostomy had a mean creatinine clearance of 86.6ml/min/1.73m2, with a mean serum creatinine level of 0.6mg/dl. Graft survival rate was 100%. Early kidney transplantation into a vesicostomy permits a resolution of the ESRD, avoiding deleterious effects related to dialysis. With a low rate of UTIs, we found no graft loss due to infectious complications. This strategy permits careful planning and better timing for the urinary tract reconstruction without delaying kidney transplantation. Kidney transplantation in pediatric patients with vesicostomy seems to be a safe and effective strategy. UTI rate was similar to that reported in the literature of patients with corrected urinary anomalies undergoing kidney transplantation without urinary diversion.