Amphiregulin, ST2,and REG3α Biomarker Risk Algorithms as Predictors of Non-Relapse Mortality in Patients with Acute GVHD.

Graft-vs-host disease (GVHD) is a major cause of non-relapse mortality (NRM) following allogeneic hematopoietic cell transplant (HCT). Algorithms containing either the GI GVHD biomarker amphiregulin (AREG) or a combination of two GI GVHD biomarkers, (ST2+REG3α) when measured at GVHD diagnosis are validated predictors of NRM risk, but have never been assessed in the same patients using identical statistical methods. We measured serum concentrations of ST2, REG3, and AREG by ELISA at the time of GVHD diagnosis in 715 patients divided by date of transplant into training (2004-2015) and validation (2015-2017) cohorts. The training cohort (n=341) was used to develop algorithms for predicting probability of 12 month NRM that contained all possible combinations of 1-3 biomarkers and a threshold corresponding to the concordance probability was used to stratify patients for risk of NRM. Algorithms were compared to each other based on several metrics including the area under the receiver operating characteristics curve (AUC), proportion of patients correctly classified, sensitivity, and specificity using only the validation cohort (n=374). All algorithms were strong discriminators of 12 month NRM, whether or not patients were systemically treated (n=321). An algorithm containing only ST2+REG3α had the highest AUC (0.757), correctly classified the most patients (75%), and more accurately risk stratified those who developed Minnesota standard risk GVHD and for patients who received post-transplant cyclophosphamide-based prophylaxis. An algorithm containing only AREG more accurately risk stratified patients with Minnesota high risk GVHD. Combining ST2, REG3α, and AREG into a single algorithm did not improve performance.

The MAGIC algorithm probability predicts treatment response and long-term outcomes to second-line therapy for acute GVHD.

The significance of biomarkers at second-line treatment for acute graft-versus-host disease (GVHD) is not well characterized. We analyzed clinical data and serum samples at initiation of second-line systemic treatment of acute GVHD from 167 patients from 17 centers of the Mount Sinai Acute GVHD International Consortium (MAGIC) between 2016 and 2021. Sixty-two patients received ruxolitinib-based therapy while 102 received other systemic agents. In agreement with prospective trials, ruxolitinib resulted in higher day 28 (D28) ORR compared to non-ruxolitinib therapies (55% vs 31%, P=0.003) and patients who received ruxolitinib had significantly lower non-relapse mortality (NRM) than those who received non-ruxolitinib therapies (point estimates at 2-year: 35% vs 61%, p=0.002). Biomarker analyses demonstrated that the benefit from ruxolitinib was observed only in patients with low MAGIC algorithm probabilities (MAPs) at the start of second-line treatment. Among patients with a low MAP, those who received ruxolitinib experienced significantly lower NRM than those who received non-ruxolitinib therapies (point estimates at 2-year: 12% vs 41%, p=0.016). However, patients with a high MAP experienced high NRM regardless of treatment with ruxolitinib or non-ruxolitinib therapies (point estimates at 2-year: 67% vs 80%, p=0.65). A landmark analysis demonstrated that the relationship between D28 response and NRM largely depends on the MAP level at initiation of second-line therapy. In conclusion, the MAP measured at second-line systemic treatment for acute GVHD predicts treatment response and NRM. Outcomes of patients with high MAP are poor, regardless of treatment choice, and ruxolitinib appears to primarily benefit patients with low MAP.

ASTCT Committee on Practice Guidelines Survey on Evaluation & Management of Relapsed Refractory Multiple Myeloma after Failure of Chimeric Antigen Receptor T-Cell Therapy.

Chimeric antigen receptor T-cell therapy (CAR-T) has revolutionized the management of relapsed and/or refractory multiple myeloma (RRMM). However, CAR-T treatment failure is not uncommon and remains a major therapeutic challenge. There is substantial variability across transplantation and cellular therapy programs in assessing and managing post CAR-T failures in RRMM. The American Society for Transplantation and Cellular Therapy (ASTCT) Committee on Practice Guidelines conducted an online cross-sectional survey between September 2023 and December 2023 to determine the myeloma, transplantation and cellular therapy physicians' practice patterns for surveillance, diagnosis, and management of CAR-T failure. The intent of this survey was to understand clinical practice patterns and identify areas for further investigation. E-mail surveys were sent to 1311 ASTCT physician members and 80 (6.1%) respondents completed the survey who identified as 58% white, 66% male, and 51% had >10 years of clinical experience. Eighty-nine percent of respondents were affiliated with university/teaching centers; 56% had myeloma-focused transplantation and/or cellular therapy practices. Post-CAR-T surveillance laboratory studies were commonly done every 4 weeks, while surveillance bone marrow biopsies and/or imaging surveillance were most commonly done at 3 months. Sixty-four percent of respondents would often or always consider biopsy or imaging to confirm relapse. The most popular post- CAR-T-failure rescue regimen was a GPRC5D-directed immunotherapy (30%) for relapses occurring ≤3 months and BCMA-directed bispecific therapies (32.5%) for relapses >3 months. Forty-one percent of respondents endorsed post-CAR-T prolonged cytopenia as "often" or "always" being a barrier to next-line therapy; 53% had offered stem cell boost as a mitigation approach. Substantial cross-center variation in practice patterns raises the need for collaborative studies and expert clinical recommendations to describe best practices for post CAR-T disease surveillance, optimal work-up for treatment failure, and choice of rescue therapies.

A Validated Risk Stratification That Incorporates MAGIC Biomarkers Predicts Long-Term Outcomes in Pediatric Patients with Acute GVHD.

Acute graft versus host disease (GVHD) is a common and serious complication of allogeneic hematopoietic cell transplantation (HCT) in children but overall clinical grade at onset only modestly predicts response to treatment and survival outcomes. Two tools to assess risk at initiation of treatment were recently developed. The Minnesota risk system stratifies children for risk of nonrelapse mortality (NRM) according to the pattern of GVHD target organ severity. The Mount Sinai Acute GVHD International Consortium (MAGIC) algorithm of 2 serum biomarkers (ST2 and REG3α) predicts NRM in adult patients but has not been validated in a pediatric population. We aimed to develop and validate a system that stratifies children at the onset of GVHD for risk of 6-month NRM. We determined the MAGIC algorithm probabilities (MAPs) and Minnesota risk for a multicenter cohort of 315 pediatric patients who developed GVHD requiring treatment with systemic corticosteroids. MAPs created 3 risk groups with distinct outcomes at the start of treatment and were more accurate than Minnesota risk stratification for prediction of NRM (area under the receiver operating curve (AUC), .79 versus .62, P = .001). A novel model that combined Minnesota risk and biomarker scores created from a training cohort was more accurate than either biomarkers or clinical systems in a validation cohort (AUC .87) and stratified patients into 2 groups with highly different 6-month NRM (5% versus 38%, P < .001). In summary, we validated the MAP as a prognostic biomarker in pediatric patients with GVHD, and a novel risk stratification that combines Minnesota risk and biomarker risk performed best. Biomarker-based risk stratification can be used in clinical trials to develop more tailored approaches for children who require treatment for GVHD.

Third-party fecal microbiota transplantation for high-risk treatment-naïve acute GVHD of the lower GI tract.

Disruption of the intestinal microbiome is observed with acute graft-versus-host disease (GVHD) of the lower gastrointestinal (LGI) tract and fecal microbiota transplantation (FMT) has successfully cured steroid-refractory cases. In this open-label, single-arm, pilot study (NCT04139577), third-party, single donor FMT was administered in combination with systemic corticosteroids to participants with high-risk acute LGI GVHD, with a focus on treatment-naïve cases. Participants were scheduled to receive one induction dose (15 capsules/day for 2 consecutive days), followed by 3 weekly maintenance doses, consisting of 15 capsules/dose. The primary endpoint of the study was feasibility, which would be achieved if ≥80% of participants able to swallow ≥40 of the 75 scheduled capsules. Ten participants (9 treatment-naïve; 1 steroid-refractory) were enrolled and treated. The study met the primary endpoint, with 9 of 10 participants completing all eligible doses. Organ-specific LGI complete response rate at Day 28 was 70%. Initial clinical response was observed within 1 week for all responders and clinical responses were durable, without recurrent LGI GVHD in complete responders. Exploratory analyses suggest that alpha diversity increased following FMT. While recipient microbiome composition never achieved a high degree of donor similarity, expansion of donor-derived species and increases in tryptophan metabolites and short-chain fatty acids were observed within the first 7 days after FMT. Investigation into the use of microbiome-targeted interventions earlier in the treatment paradigm for acute LGI GVHD is warranted.

A Day 14 Endpoint for Acute GVHD Clinical Trials.

The overall response rate (ORR) 28 days after treatment has been adopted as the primary endpoint for clinical trials of acute graft versus host disease (GVHD). However, physicians often need to modify immunosuppression earlier than day (D) 28, and non-relapse mortality (NRM) does not always correlate with ORR at D28. We studied 1144 patients that received systemic treatment for GVHD in the Mount Sinai Acute GVHD International Consortium (MAGIC) and divided them into a training set (n=764) and a validation set (n=380). We used a recursive partitioning algorithm to create a Mount Sinai model that classifies patients into favorable or unfavorable groups that predicted 12 month NRM according to overall GVHD grade at both onset and D14. In the Mount Sinai model grade II GVHD at D14 was unfavorable for grade III/IV GVHD at onset and predicted NRM as well as the D28 standard response model. The MAGIC algorithm probability (MAP) is a validated score that combines the serum concentrations of suppression of tumorigenicity 2 (ST2) and regenerating islet-derived 3-alpha (REG3α) to predict NRM. Inclusion of the D14 MAP biomarker score with the D14 Mount Sinai model created three distinct groups (good, intermediate, poor) with strikingly different NRM (8%, 35%, 76% respectively). This D14 MAGIC model displayed better AUC, sensitivity, positive and negative predictive value, and net benefit in decision curve analysis compared to the D28 standard response model. We conclude that this D14 MAGIC model could be useful in therapeutic decisions and may offer an improved endpoint for clinical trials of acute GVHD treatment.

Flares of acute graft-versus-host disease: a Mount Sinai Acute GVHD International Consortium analysis.

ABSTRACT: The absence of a standardized definition for graft-versus-host disease (GVHD) flares and data on its clinical course are significant concerns. We retrospectively evaluated 968 patients across 23 Mount Sinai Acute GVHD International Consortium (MAGIC) transplant centers who achieved complete response (CR) or very good partial response (VGPR) within 4 weeks of treatment. The cumulative incidence of flares within 6 months was 22%, and flares were associated with a higher risk of nonrelapse mortality (NRM; adjusted hazard ratio [aHR], 4.84; 95% confidence interval [CI], 3.19-7.36; P < .001). Flares were more severe (grades 3/4, 41% vs 16%; P < .001) and had more frequent lower gastrointestinal (LGI) involvement (55% vs 32%; P < .001) than the initial GVHD. At CR/VGPR, elevated MAGIC biomarkers predicted the future occurrence of a flare, along with its severity and LGI involvement. In multivariate analyses, higher Ann Arbor (AA) biomarker scores at CR/VGPR were significant risk factors for flares (AA2 vs AA1: aHR, 1.81 [95% CI, 1.32-2.48; P = .001]; AA3 vs AA1: aHR, 3.14 [95% CI, 1.98-4.98; P < .001]), as were early response to initial treatment (aHR, 1.84; 95% CI, 1.21-2.80; P = .004) and HLA-mismatched unrelated donor (aHR, 1.74; 95% CI, 1.00-3.02; P = .049). MAGIC biomarkers also stratified the risk of NRM both at CR/VGPR and at the time of flare. We conclude that GVHD flares are common and carry a significant mortality risk. The occurrence of future flares can be predicted by serum biomarkers that may serve to guide adjustment and discontinuation of immunosuppression.

Group Coping Intervention in Patients With Chronic Graft-Versus-Host Disease: A Pilot Randomized Clinical Trial.

BACKGROUND: More than half the long-term survivors of allogeneic hematopoietic cell transplantation develop chronic graft-versus-host disease (GVHD), a debilitating inflammatory syndrome. Supportive interventions to assist survivors in coping with chronic GVHD are critically needed. PATIENTS AND METHODS: We conducted a pilot randomized clinical trial of a multidisciplinary group intervention (Horizons Program; n=39) versus minimally enhanced usual care (n=41) for patients with moderate or severe chronic GVHD. Horizons participants received 8 weekly sessions about GVHD and coping co-led by a transplant clinician and a behavioral health expert via a secure videoconferencing platform. Participants completed the following surveys before randomization, at 10 weeks, and at 18 weeks: Functional Assessment of Cancer Therapy-Bone Marrow Transplant Scale (FACT-BMT) for quality of life (QoL), Lee Symptom Scale for symptom burden, and Hospital Anxiety and Depression Scale-Depression Symptoms (HADS) for mood. The primary endpoint was feasibility (≥50% enrollment, ≥80% attendance in half the sessions for the Horizons arm only, and ≥80% retention). We also explored preliminary efficacy of the Horizons intervention on changes in patient-reported outcomes with linear mixed effects models and estimates of effect size at 10 weeks. RESULTS: We enrolled and registered 80 (67.2%) of 119 eligible patients (mean age, 62 years; 48.8% female). Of the participants in the Horizons Program, 84.6% attended at least half the sessions. Of registered participants, 91.3% completed assessment follow-ups (Horizons, 35/39 [89.7%]; minimally enhanced usual care, 38/41 [92.7%]). Horizons participants reported improvements in QoL (b = 2.24; d=0.53), anxiety symptoms (b = -0.10; d=0.34), and depression symptoms (b = -0.71; d=0.44) compared with participants who received minimally enhanced usual care. CONCLUSIONS: Participation in a multidisciplinary group intervention study was feasible for patients with chronic GVHD, with promising signals for improving QoL and mood. A full-scale efficacy trial is needed to confirm effects on patient-reported outcomes.

Protocol for multi-site randomized trial of inpatient palliative care for patients with hematologic malignancies undergoing hematopoietic stem cell transplantation.

BACKGROUND: Patients with hematologic malignancies undergoing hematopoietic stem cell transplantation (HSCT) commonly experience debilitating physical and psychological symptoms during a 3-4-week-hospitalization. During hospitalization, caregivers (i.e., family and friends) also endure immense emotional stress as they witness their loved one struggle with HSCT toxicities. Yet interventions to improve quality of life (QOL) and reduce psychological distress during HSCT are limited. METHODS: We are conducting a multi-site randomized controlled trial of inpatient integrated palliative and transplant care versus usual care in 360 patients hospitalized for HSCT and their caregivers at three academic centers. Intervention participants meet with a palliative care clinician at least twice weekly during the HSCT hospitalization to address their physical and psychological symptoms. Patients assigned to usual care receive all supportive care measures provided by the HSCT team and could be seen by palliative care upon request. We assess patient QOL (Functional Assessment of Cancer Therapy (FACT) - Bone Marrow Transplant), depression and anxiety symptoms (Hospital Anxiety and Depression Scale), post-traumatic stress (PTSD) symptoms (PTSD checklist), symptom burden (Edmonton Symptom Assessment Scale), and fatigue (FACT-Fatigue) as well as caregiver-reported outcomes at baseline, 2 weeks, 3-months, 6-months, and 12-months post-HSCT. The primary endpoint is to compare QOL at week-2 during HSCT hospitalization between the two groups when patients typically experience their QOL nadir during HSCT. CONCLUSIONS: This multi-site trial will define the role of palliative care for improving QOL and care for patients with hematologic malignancies undergoing HSCT and their caregivers.

Severity of Chronic Graft-versus-Host Disease and Late Effects Following Allogeneic Hematopoietic Cell Transplantation for Adults with Hematologic Malignancy.

The study aimed to determine the association of chronic graft-versus-host disease (cGVHD) diagnosis and severity with the development of subsequent neoplasms (SN) and nonmalignant late effects (NM-LE) in 2-year disease-free adult survivors following hematopoietic cell transplantation (HCT) for a hematologic malignancy. To do so, we conducted a retrospective analysis of 3884 survivors of HCT for hematologic malignancy in the Center of International Blood and Marrow Transplant Research database. We conducted a landmark analysis at the 2-year post-transplantation date, comparing first SN and NM-LE in survivors with and without cGVHD. The cumulative incidence (CuI) of SN and NM-LE were estimated through 10 years post-HCT in both groups, with death or disease relapse as a competing risk. Cox proportional hazards models were used to evaluate the associations of cGVHD and its related characteristics with the development of SN and NM-LE. The estimated 10-year CuI of SN in patients with GVHD (n = 2669) and patients without cGVHD (n = 1215) was 15% (95% confidence interval [CI], 14% to 17%) versus 9% (7.2% to 11%) (P < .001). cGVHD by 2 years post-HCT was independently associated with SN (hazard ratio [HR], 1.94; 95% CI, 1.53 to 2.46; P < .0001) with a standardized incidence ratio of 3.2 (95% CI, 2.9 to 3.5; P < .0001). Increasing severity of cGVHD was associated with an increased risk of SN. The estimated 10-year CuI of first NM-LE in patients with and without cGVHD was 28 (95% CI, 26% to 30%) versus 13% (95% CI, 11% to 15%) (P < .001). cGVHD by 2 years post-HCT was independently associated with NM-LE (HR, 2.23; 95% CI, 1.81 to 2.76; P < .0001). Multivariate analysis of cGVHD-related factors showed that increasing severity of cGVHD, extensive grade, having both mucocutaneous and visceral involvement, and receiving cGVHD treatment for >12 months were associated with the greatest magnitude of risk for NM-LE. cGVHD was closely associated with both SN and NM-LE in adult survivors of HCT for hematologic malignancy. Patients identified as having more severe involvement and both mucocutaneous and visceral organ involvement may warrant enhanced monitoring and screening for SNs and NM-LEs. However, caution is warranted when interpreting these results, as patients with cGVHD may have more vigilant post-transplantation health care and surveillance for late effects.

AKI treated with kidney replacement therapy in critically Ill allogeneic hematopoietic stem cell transplant recipients.

Acute kidney injury (AKI) is a frequent complication following allogeneic hematopoietic stem cell transplantation (allo-HSCT), but few studies have focused on AKI treated with kidney replacement therapy (AKI-KRT), particularly among critically ill patients. We investigated the incidence, risk factors, and 90-day mortality associated with AKI-KRT in 529 critically ill adult allo-HSCT recipients admitted to the ICU within 1-year post-transplant at two academic medical centers between 2011 and 2021. AKI-KRT occurred in 111 of the 529 patients (21.0%). Lower baseline eGFR, veno-occlusive disease, thrombotic microangiopathy, admission to an ICU within 90 days post-transplant, and receipt of invasive mechanical ventilation (IMV), total bilirubin ≥5.0 mg/dl, and arterial pH <7.40 on ICU admission were each associated with a higher risk of AKI-KRT. Of the 111 patients with AKI-KRT, 97 (87.4%) died within 90 days. Ninety-day mortality was 100% in each of the following subgroups: serum albumin ≤2.0 g/dl, total bilirubin ≥7.0 mg/dl, arterial pH ≤7.20, IMV with moderate-to-severe hypoxemia, and ≥3 vasopressors/inotropes at KRT initiation. AKI-KRT was associated with a 6.59-fold higher adjusted 90-day mortality in critically ill allo-HSCT vs. non-transplanted patients. Short-term mortality remains exceptionally high among critically ill allo-HSCT patients with AKI-KRT, highlighting the importance of multidisciplinary discussions prior to KRT initiation.

Spatial transcriptomics reveals distinct tissue niches linked with steroid responsiveness in acute gastrointestinal GVHD.

Severe acute graft-versus-host disease (aGVHD) is associated with significant mortality and morbidity, especially in steroid-resistant (SR) cases. Spatial transcriptomic technology can elucidate tissue-based interactions in vivo and possibly identify predictors of treatment response. Tissue sections from 32 treatment-naïve patients with biopsy-confirmed lower gastrointestinal (GI) aGVHD were obtained. The GeoMx digital spatial profiler was used to capture transcriptome profiles of >18 000 genes from different foci of immune infiltrates, colonic epithelium, and vascular endothelium. Each tissue compartment sampled showed 2 distinct clusters that were analyzed for differential expression and spatially resolved correlation of gene signatures. Classic cell-mediated immunity signatures, normal differentiated epithelial cells, and inflamed vasculature dominated foci sampled from steroid-sensitive cases. In contrast, a neutrophil predominant noncanonical inflammation with regenerative epithelial cells and some indication of angiogenic endothelial response was overrepresented in areas from SR cases. Evaluation of potential prognostic biomarkers identified ubiquitin specific peptidase 17-like (USP17L) family of genes as being differentially expressed in immune cells from patients with worsened survival. In summary, we demonstrate distinct tissue niches with unique gene expression signatures within lower GI tissue from patients with aGVHD and provide evidence of a potential prognostic biomarker.

Updated Indications for Immune Effector Cell Therapy: 2023 Guidelines from the American Society for Transplantation and Cellular Therapy.

The American Society for Transplantation and Cellular Therapy (ASTCT) published its guidelines on indications for autologous and allogeneic hematopoietic cell transplantation (HCT) and immune effector cell therapy (IECT) in 2020. Since then, we have witnessed rapid advancements in the field of IECT, resulting in several new chimeric antigen receptor T cell (CAR-T) products and disease indications being approved by the US Food and Drug Administration (FDA). To keep abreast of these practice changes, the ASTCT Committee on Practice Guidelines commissioned a focused update covering CAR-T therapy indications. Here we present updated ASTCT recommendations on indications for CAR-T therapy. Only FDA-approved indications for CAR-T were recommended and categorized as "standard of care," where the indication is well defined and supported by evidence. The ASTCT will continue to periodically review these guidelines and update them as new evidence becomes available.

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

Late 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.

A phase 2 study of pembrolizumab after autologous stem cell transplantation in patients with T-cell non-Hodgkin lymphoma.

Autologous stem cell transplantation (ASCT) is often used as consolidation for several subtypes of peripheral T-cell lymphoma (PTCL) in first remission. However, many patients relapse after ASCT and have a very poor prognosis. There are no approved treatment options for posttransplantation maintenance or consolidation in PTCL. PD-1 blockade has demonstrated some efficacy for patients with PTCL. We, therefore, conducted a phase 2 multicenter study of the anti-PD-1 monoclonal antibody pembrolizumab after ASCT in patients with PTCL in first remission. Pembrolizumab was administered at 200 mg IV every 3 weeks for up to 8 cycles within 21 days from post-ASCT discharge (and within 60 days of stem cell infusion). The primary end point was progression-free survival (PFS) at 18 months after ASCT. Twenty-one patients were treated in this study and 67% (n = 14) completed 8 cycles of treatment. Among all patients who were evaluable, 13 of 21 were alive and achieved PFS at 18 months after ASCT, meeting the study's primary end point. The estimated 18-month PFS was 83.6% (95% confidence interval [CI], 68-100), and overall survival 94.4% (95% CI, 84-100). The toxicity profile was consistent with the known toxicity profile of pembrolizumab, with no grade 5 toxicities. In conclusion, PD-1 blockade after ASCT with pembrolizumab is feasible with a favorable safety profile and promising activity, supporting further confirmatory studies. This trial was registered at www.clinicaltrials.gov as #NCT02362997.

A simple prognostic system in patients with myelofibrosis undergoing allogeneic stem cell transplantation: a CIBMTR/EBMT analysis.

To develop a prognostic model for patients undergoing allogeneic hematopoietic cell transplantation (allo-HCT) for myelofibrosis (MF), we examined the data of 623 patients undergoing allo-HCT between 2000 and 2016 in the United States (the Center for International Blood and Marrow Transplant Research [CIBMTR] cohort). A Cox multivariable model was used to identify factors prognostic of mortality. A weighted score using these factors was assigned to patients who received transplantation in Europe (the European Bone Marrow Transplant [EBMT] cohort; n = 623). Patient age >50 years (hazard ratio [HR], 1.39; 95% confidence interval [CI], 0.98-1.96), and HLA-matched unrelated donor (HR, 1.29; 95% CI, 0.98-1.7) were associated with an increased hazard of death and were assigned 1 point. Hemoglobin levels <100 g/L at time of transplantation (HR, 1.63; 95% CI, 1.2-2.19) and a mismatched unrelated donor (HR, 1.78; 95% CI, 1.25-2.52) were assigned 2 points. The 3-year overall survival (OS) in patients with a low (1-2 points), intermediate (3-4 points), and high score (5 points) were 69% (95% CI, 61-76), 51% (95% CI, 46-56.4), and 34% (95% CI, 21-49), respectively (P < .001). Increasing score was predictive of increased transplant-related mortality (TRM; P = .0017) but not of relapse (P = .12). The derived score was predictive of OS (P < .001) and TRM (P = .002) but not of relapse (P = .17) in the EBMT cohort as well. The proposed system was prognostic of survival in 2 large cohorts, CIBMTR and EBMT, and can easily be applied by clinicians consulting patients with MF about the transplantation outcomes.