Hematopoietic cell transplantation (HCT) was developed more than 65 years ago to treat malignant blood disorders and irreversible bone marrow failures, with the aim of replacing a diseased hematopoietic system with a healthy one (allogeneic HCT). Decades later, the procedure was adapted to apply maximal chemotherapy or radiotherapy, which would result in bone marrow failure, but could be remedied by an infusion of a patient\'s own cryopreserved bone marrow (autologous HCT). Both treatments are high-risk and complex, especially during the initial phases. However, concerted efforts, vision, and collaboration between physicians and centers worldwide have resulted in HCT becoming a standard of care for many hematological disorders with progressive improvements in outcomes. Registries and the collaboration of societies worldwide have enabled the delivery of this curative therapy to many patients with fatal hematological diseases. More than 1.5 million HCT were performed between 1957 and 2019, and activity is continuously increasing worldwide.

BACKGROUND: Chronic graft-versus-host disease (GVHD) is a leading cause of late morbidity and mortality after allogeneic hematopoietic cell transplantation. Despite significant progress in chronic GVHD therapies, challenges remain in understanding pleomorphic phenotypes and varying response to treatment. The goal of the Predicting the Quality of Response to Specific Treatments (PQRST) in chronic GVHD study is to identify predictors of treatment response. This report describing the study design seeks to raise awareness and invite collaborations with investigators who wish to access clinical data and research samples from this study.
METHODS: This is a prospective, observational cohort study involving data collection from patients who are beginning first-, second-, or third-line systemic therapy for chronic GVHD with defined agents. Evaluable participants will have baseline assessments and research samples prior to starting the index therapy, and 1 month after starting treatment. Response assessments occur at 3 and 6 months after start of treatment, or if a new systemic therapy is started before 6 months. Target enrollment is approximately 200 patients at 8 institutions, with at least 6 months of follow up to determine response to index therapy.
RESULTS: Enrollment started in July 2020 and was delayed due to the COVID-19 pandemic; as of 3/1/2024, 137 evaluable participants have been enrolled.
CONCLUSIONS: The Chronic GVHD Consortium \"PQRST\" is a large longitudinal cohort study that aims to investigate predictors of treatment response by identifying biologically and clinically defined patient subgroups. We welcome investigators to collaborate in the use of these data.
BACKGROUND: NCT04431479.

The management of elderly patients diagnosed with acute myelogenous leukemia (AML) is complicated by high relapse risk and comorbidities that often preclude access to allogeneic hematopoietic cellular transplantation (allo-HCT). In recent years, fast-paced FDA drug approval has reshaped the therapeutic landscape, with modest, albeit promising improvement in survival. Still, AML outcomes in elderly patients remain unacceptably unfavorable highlighting the need for better understanding of disease biology and tailored strategies. In this review, we discuss recent modifications suggested by European Leukemia Network 2022 (ELN-2022) risk stratification and review recent aging cell biology advances with the discussion of four AML cases. While an older age, >60 years, does not constitute an absolute contraindication for allo-HCT, the careful patient selection based on a detailed and multidisciplinary risk stratification cannot be overemphasized.

Despite aggressive multimodal treatment, the outcomes of pediatric patients with high-risk (HR) neuroblastoma (NB) remain poor. The rationale for allogeneic hematopoietic stem cell transplantation (allo-HCT) to treat NB was based on the possible graft-versus-tumor effect; however, toxicity limits its efficacy. We sought to prospectively assess the feasibility and efficacy of allo-HCT using a reduced-intensity conditioning regimen in pediatric patients with HR NB in a multicenter phase II trial. Primary endpoints were the rate of neutrophil and platelet engraftment, 5-year transplantation-related mortality (TRM), and disease-free survival (DFS). Secondary endpoint measures included the incidence of acute graft-versus-host disease (aGVHD) and chronic GVHD. Fifty-one patients were enrolled in the study. The 5-year cumulative incidence (CuI) of TRM was 29.4 ± 6.4%, and that of DFS was 11.8 ± 4.5%. Patients undergoing allo-HCT within 1 year of diagnosis or with bone marrow as their stem cell source had a higher DFS probability. The CuI of neutrophil engraftment, platelet engraftment, and grade II-IV aGVHD was 97.9 ± 2.1%, 93.8 ± 3.5%, and 47.1 ± 7.0%, respectively. The development of new therapeutic strategies could further improve disease control.

The success of allogeneic hematopoietic cell transplantation (HCT) as therapy for hematologic conditions is negatively impacted by the occurrence of graft-versus-host disease (GVHD). Tissue damage, caused, for example, by chemotherapy and radiotherapy, is a key factor in GVHD pathogenesis. Innate lymphoid cells (ILCs) are important mediators of tissue repair and homeostasis. The presence of ILCs before, and enhanced ILC reconstitution after, allogeneic HCT is associated with a reduced risk to develop mucositis and GVHD. However, ILC reconstitution after allogeneic HCT is slow and often incomplete. A way to replenish the pool of ILC relies on the differentiation of hematopoietic progenitor cells (HPCs) into ILC.
We developed an ex vivo stromal cell-containing culture system to study the capacity of HPCs to differentiate into all mature helper ILC subsets.
ILC development depended on the source of HPCs. ILCs developed at high frequencies from umbilical cord blood- and fetal liver-derived HPC and at low frequencies when HPCs were obtained from allogeneic or autologous adult HCT grafts or healthy adult bone marrow. Although all helper ILC subsets could be generated from adult HPC sources, development of tissue protective ILC2 and NKp44+ ILC3 was notoriously difficult.
Our data suggest that slow ILC recovery after allogeneic HCT may be related to an intrinsic incapability of adult HPC to develop into ILC.

Pneumocystis pneumonia (PCP) is a life-threatening complication after allogeneic hematopoietic cell transplantation (allo-HCT). However, allo-HCT procedures have evolved toward older patients, unrelated donors, and reduced-intensity conditioning, possibly modifying the risks. Polymerase chain reaction (PCR), widely used nowadays, is more sensitive than microscopy diagnostic methods. This study aimed to assess the factors associated with PCP in allo-HCT recipients within 2 years of HCT and managed according to current procedures. This multicenter, nested case-control study included PCP cases diagnosed by PCR, cytology, or immunofluorescence on bronchoalveolar lavage fluid between 2016 and 2018. Two controls per case were selected from the ProMISe registry and matched for the center, transplant date, and underlying disease. Fifty-two cases and 104 controls were included among the 5452 patients who underwent allo-HCT in the participating centers. PCP occurred at a median of 11.5 months after transplantation. The mortality rate was 24% on day 30 after the PCP diagnosis and 37% on day 90. The clinical presentation and mortality rates of the 24 patients diagnosed using only PCR were not different from those diagnosed with microscopy methods. Our study demonstrates a substantial incidence of, and mortality from, PCP, after allogeneic HCT despite well-established prophylactic approaches. In our experience, PCP nowadays occurs later after transplant than previously reported, justifying the prolongation of prophylaxis after six months in many cases. Allo-HCT recipients diagnosed with PCR as the only PCP marker should benefit from specific treatment as for other patients.

BACKGROUND: Prediction of outcomes following allogeneic hematopoietic cell transplantation (HCT) remains a major challenge. Machine learning (ML) is a computational procedure that may facilitate the generation of HCT prediction models. We sought to investigate the prognostic potential of multiple ML algorithms when applied to a large single-center allogeneic HCT database.
METHODS: Our registry included 2,697 patients that underwent allogeneic HCT from January 1976 to December 2017. 45 pretransplant baseline variables were included in the predictive assessment of each ML algorithm on overall survival (OS) as determined by area under the curve (AUC). Pretransplant variables used in the EBMT ML study (Shouval et al., 2015) were used as a benchmark for comparison.
RESULTS: On the entire dataset, the random forest (RF) algorithm performed best (AUC 0.71 ± 0.04) compared to the second-best model, logistic regression (LR) (AUC = 0.69 ± 0.04) (p < 0.001). Both algorithms demonstrated improved AUC scores using all 45 variables compared to the limited variables examined by the EBMT study. Survival at 100 days post-HCT using RF on the full dataset discriminated patients into different prognostic groups with different 2-year OS (p < 0.0001). We then examined the ML methods that allow for significant individual variable identification, including LR and RF, and identified matched related donors (HR = 0.49, p < 0.0001), increasing TBI dose (HR = 1.60, p = 0.006), increasing recipient age (HR = 1.92, p < 0.0001), higher baseline Hb (HR = 0.59, p = 0.0002), and increased baseline FEV1 (HR = 0.73, p = 0.02), among others.
CONCLUSIONS: The application of multiple ML techniques on single-center allogeneic HCT databases warrants further investigation and may provide a useful tool to identify variables with prognostic potential.

Dedicator of cytokinesis 8 (DOCK8) deficiency is a rare autosomal recessive inborn error of immunity (IEI) characterized by eczematous dermatitis, elevated serum IgE, and recurrent infections, comprising a seemingly hyper-IgE syndrome (HIES). DOCK8 deficiency is only curable with allogeneic hematopoietic cell transplantation (HCT), but the outcome of HCT from alternative donors is not fully understood. Here, we describe the cases of two Japanese patients with DOCK8 deficiency who were successfully treated by allogeneic HCT from alternative donors. Patient 1 underwent cord blood transplantation at the age of 16 years, and Patient 2 underwent haploidentical peripheral blood stem cell transplantation with post-transplant cyclophosphamide at the age of 22 years. Each patient received a fludarabine-based conditioning regimen. Their clinical manifestations, including refractory molluscum contagiosum, promptly improved post-HCT. They achieved successful engraftment and immune reconstitution without serious complications. Alternative donor sources such as cord blood and haploidentical donors can be options for allogeneic HCT for DOCK8 deficiency.

Older patients with AML/MDS have a poor prognosis with alloHCT as the only curative option. However alloHCT is challenging given its high TRM. Recently, a composite endpoint of GRFS was proposed to define transplant success. A single centre retrospective analysis was performed to determine the main variables influencing GRFS.
91 consecutive patients≥ 60 years (median 64 years, range 60-74) with AML/MDS who received reduced-intensity alloHCT during 2001-2017 analysed. Disease risk index (DRI) at HCT was low/intermediate in 47pts (52%) and high in 44 pts (48%).
After median follow-up for survivors of 56 months (range 7-144), 37 (40.6%) patients were alive. The OS, LFS and GRFS were 61.4%, 58.1%, 49.1% at 1 year and 35.5%, 32.3% and 23.1% at 5 years, respectively. The 1-year and 5-year incidences of NRM and relapse were 26.9%, 21.3% and 47.9% and 35.4%, respectively. In univariate analysis, high DRI was the strongest factor for worse OS (HR 2.121; p = 0.049), LFS (HR 1.924; p = 0.0123) and GRFS (HR 2.319; p = 0.0005). The donor age ≥ 62 years had a negative impact on OS (HR 2.110; p = 0.0345) and GRFS (HR 2.014; p = 0.0341). High DRI (HR 2.652; p = 0.0003) and donor age (HR 2.304; p = 0.0257) retained its significance in multivariate analysis for GRFS.
A significant portion of older patients with myeloid malignancies survive alloHCT without experiencing GRFS event with DRI as the main determinant of outcome. Negative impact of donor age≥ 62 years suggests preference of a young donor, regardless of being related or unrelated.

Many patients with hematological malignancies, such as acute myeloid leukemia, receive an allogeneic hematopoietic cell transplantation (HCT) to cure their underlying condition. Allogeneic HCT recipients are exposed to various elements during the pre-, peri- and post-transplant period that can disrupt intestinal microbiota, including chemo- and radiotherapy, antibiotics, and dietary changes. The dysbiotic post-HCT microbiome is characterized by low fecal microbial diversity, loss of anaerobic commensals, and intestinal domination, particularly by Enterococcus species, and is associated with poor transplant outcomes. Graft-versus-host disease (GvHD) is a frequent complication of allogeneic HCT caused by immunologic disparity between donor and host cells and results in tissue damage and inflammation. Microbiota injury is particularly pronounced in allogeneic HCT recipients who go on to develop GvHD. At present, manipulation of the microbiome for example, via dietary interventions, antibiotic stewardship, prebiotics, probiotics, or fecal microbiota transplantation, is widely being explored to prevent or treat gastrointestinal GvHD. This review discusses current insights into the role of the microbiome in GvHD pathogenesis and summarizes interventions to prevent and treat microbiota injury.