CXCL9 Predicts Severity at the Onset of Chronic Graft-versus-host Disease

Unlocking protein-based biomarker potential for graft-versus-host disease following allogenic hematopoietic stem cell transplants

Despite the numerous advantages of allogeneic hematopoietic stem cell transplants (allo-HSCT), there exists a notable association with risks, particularly during the preconditioning period and predominantly post-intervention, exemplified by the occurrence of graft-versus-host disease (GVHD). Risk stratification prior to symptom manifestation, along with precise diagnosis and prognosis, relies heavily on clinical features. A critical imperative is the development of tools capable of early identification and effective management of patients undergoing allo-HSCT. A promising avenue in this pursuit is the utilization of proteomics-based biomarkers obtained from non-invasive biospecimens. This review comprehensively outlines the application of proteomics and proteomics-based biomarkers in GVHD patients. It delves into both single protein markers and protein panels, offering insights into their relevance in acute and chronic GVHD. Furthermore, the review provides a detailed examination of the site-specific involvement of GVHD. In summary, this article explores the potential of proteomics as a tool for timely and accurate intervention in the context of GVHD following allo-HSCT.

EASIX-1year and late mortality after allogeneic stem cell transplantation

Patients with hematological malignancies who survive the first year after allogeneic stem cell transplantation (allo-SCT) without relapse have a substantial risk of nonrelapse mortality (NRM) and missing predictive markers. The Endothelial Activation and Stress Index (EASIX) predicts endothelial complications and NRM early after allo-SCT. We hypothesized that EASIX assessed 1 year after allo-SCT in survivors who were disease free may predict late NRM. Survivors who were relapse-free at 1 year after allo-SCT were retrospectively studied in 2 independent cohorts (training cohort, n = 610; merged validation cohort, n = 852). EASIX determined 1 year after allo-SCT correlated with the overall survival (OS), NRM, and relapse. Serum endothelial and inflammatory markers were measured in the training cohort and correlated with EASIX-1year, which predicted OS and NRM but not relapse risk in both the training and validation cohorts in univariable and multivariable Cox regression analyses. Brier score and c-index analyses validated the univariable EASIX effects. There was no significant interaction between EASIX-1year and incidence of chronic graft-versus-host disease (GVHD) on OS. EASIX-1year predicted the outcome irrespective of preexisting comorbidities. Principal causes of NRM in both training and validation cohorts were infections with and without GVHD as well as cardiovascular complications. EASIX-1year correlated with sCD141 and interleukin-18 but not with C-reactive protein, suppressor of tumorigenicity-2, angiopoietin-2, CXCL9, or CXCL8. To our knowledge, EASIX-1year is the first validated predictor of late overall and NRM. Patients who are high risk as defined by EASIX-1year might be considered for intensified surveillance and prophylactic measures.

Chronic GvHD NIH Consensus Project Biology Task Force: evolving path to personalized treatment of chronic GvHD

Chronic graft-versus-host disease (cGvHD) remains a prominent barrier to allogeneic hematopoietic stem cell transplantion as the leading cause of nonrelapse mortality and significant morbidity. Tremendous progress has been achieved in both the understanding of pathophysiology and the development of new therapies for cGvHD. Although our field has historically approached treatment from an empiric position, research performed at the bedside and bench has elucidated some of the complex pathophysiology of cGvHD. From the clinical perspective, there is significant variability of disease manifestations between individual patients, pointing to diverse biological underpinnings. Capitalizing on progress made to date, the field is now focused on establishing personalized approaches to treatment. The intent of this article is to concisely review recent knowledge gained and formulate a path toward patient-specific cGvHD therapy.

Pretransplantation EASIX Score Predicts Nonrelapse and Overall Mortality of Adult Patients Undergoing Single-Unit Unrelated Cord Blood Transplantation

The Endothelial Activation and Stress Index (EASIX) is a laboratory-based score used to estimate endothelial damage occurring after hematopoietic cell transplantation (HCT). The EASIX score exhibits dynamic changes during the course of transplantation and has been identified as a predictor of nonrelapse mortality (NRM) and worse overall survival (OS) in studies focused mainly on patients who received matched related or unrelated donor allogeneic HCT. However, the role of EASIX score in the setting of cord blood transplantation (CBT) is unclear. This study examined the association between pretransplant EASIX score and post-transplantation outcomes in adult patients undergoing single-unit CBT. We retrospectively evaluated the impact of EASIX score at different time points on post-transplantation outcomes in adults following single-unit unrelated CBT between 1998 and 2022 at our institution. EASIX scores were calculated at the start of conditioning (EASIX-PRE), at day 30 post-CBT (EASIX-d30), at day 100 post-CBT (EASIX-d100), and at the onset of grade II-IV acute graft-versus-host disease (GVHD) (EASIX-GVHD II-IV). A total of 317 patients were included in this study. In the multivariate analysis, log2-EASIX-PRE (continuous variable) was significantly associated with lower risks of neutrophil engraftment (hazard ratio [HR], .87; 95% confidence interval [CI], .80 to .94; P < .001) and platelet engraftment (HR, .91; 95% CI, .83 to .99; P = .047), lower risk of grade II-IV acute GVHD (HR, .85; 95% CI, .76 to .94; P = .003), and higher risk of veno-occlusive disease/sinusoidal obstruction syndrome (VOD/SOS) (HR, 1.44; 95% CI, 1.03 to 2.02; P = .032). Log2-EASIX-PRE also was significantly associated with higher NRM (HR, 1.42; 95% CI, 1.08 to 1.86; P = .011) and worse OS (HR, 1.26; 95% CI, 1.08 to 1.46; P = .003), but not with relapse (HR, 1.02; 95% CI, .88 to 1.18; P = .780). Similarly, log2-EASIX-d30 (HR, 1.60; 95% CI, 1.26 to 2.05; P < .001), and log2-EASIX-d100 (HR, 2.01; 95% CI, 1.63 to 2.48; P < .001) were also significantly associated with higher NRM, but log2-EASIX-GVHD II-IV was not (HR, 1.15; 95% CI, .85 to 1.55; P = .360). Pretransplantation EASIX score is a powerful predictor of engraftment, VOS/SOS, NRM, and OS in adult patients undergoing single-unit unrelated CBT who mainly received intensified conditioning regimens. EASIX is an easily evaluable and dynamic prognostic score for accurately predicting post-transplantation outcomes in patients at any time during the course of allogeneic HCT, particularly for CBT.

A diagnostic classifier for pediatric chronic graft-versus-host disease: results of the ABLE/PBMTC 1202 study

The National Institutes of Health Consensus criteria for chronic graft-versus-host disease (cGVHD) diagnosis can be challenging to apply in children, making pediatric cGVHD diagnosis difficult. We aimed to identify diagnostic pediatric cGVHD biomarkers that would complement the current clinical criteria and help differentiate cGVHD from non-cGVHD. The Applied Biomarkers of Late Effects of Childhood Cancer (ABLE) study, open at 27 transplant centers, prospectively evaluated 302 pediatric patients after hematopoietic cell transplant (234 evaluable). Forty-four patients developed cGVHD. Mixed and fixed effect regression analyses were performed on diagnostic cGVHD onset blood samples for cellular and plasma biomarkers, with individual markers declared relevant if they met 3 criteria: an effect ratio ≥1.3 or ≤0.75; an area under the curve (AUC) of ≥0.60; and a P value <5.814 × 10-4 (Bonferroni correction) (mixed effect) or <.05 (fixed effect). To address the complexity of cGVHD diagnosis in children, we built a machine learning-based classifier that combined multiple cellular and plasma biomarkers with clinical factors. Decreases in regulatory natural killer cells, naïve CD4 T helper cells, and naïve regulatory T cells, and elevated levels of CXCL9, CXCL10, CXCL11, ST2, ICAM-1, and soluble CD13 (sCD13) characterize the onset of cGVHD. Evaluation of the time dependence revealed that sCD13, ST2, and ICAM-1 levels varied with the timing of cGVHD onset. The cGVHD diagnostic classifier achieved an AUC of 0.89, with a positive predictive value of 82% and a negative predictive value of 80% for diagnosing cGVHD. Our polyomic approach to building a diagnostic classifier could help improve the diagnosis of cGVHD in children but requires validation in future prospective studies. This trial was registered at www.clinicaltrials.gov as #NCT02067832.

Recent Advances and Research Progress in Biomarkers for Chronic Graft Versus Host Disease

Chronic graft-versus host disease (cGVHD) is a major risk for patients undergoing allogeneic hematopoietic stem cell transplantation. With the emergence of novel therapies and the increased understanding of the mechanisms underlying cGVHD, there are more options for cGVHD treatment. Regardless of improvements in treatment, diagnosis mainly depends on identification of symptoms, which makes precise treatment a challenge. Numerous biomarkers for cGVHD have been validated and have demonstrated strong associations with prognosis and response to treatment. The most common biomarkers mainly include critical types of immune cells, chemokines, cytokines, microRNAs, and autoantibodies, all of which play important roles in the development of cGVHD. Compared to traditional tools, biomarkers have several advantages, for example, they can be applied for early diagnosis, to identify cGVHD risk before onset, and predict which therapy is most likely to benefit patients. In this review, we summarize biomarkers with potential clinical value and discuss future applications.

Elevated ADA2 Enzyme Activity at the Onset of Chronic Graft-versus-Host Disease in Children

Adenosinergic signaling has potent, context-specific effects on immune cells, particularly on the dysregulation of lymphocytes. This in turn may have a role in immune activation and loss of tolerance in such diseases as chronic graft-versus-host disease (chronic GVHD). We assessed whether changes in the enzymatic activity of adenosine deaminase 2 (ADA2), an enzyme that depletes adenosine in the extracellular space via conversion to inosine, may be associated with the onset of chronic GVHD. ADA2-specific enzyme activity was measured in plasma samples from 230 pediatric hematopoietic stem cell transplantation (HSCT) recipients enrolled on the Applied Biomarkers of Late Effects of Childhood Cancer (ABLE)/Pediatric Blood and Marrow Transplant Consortium (PBMTC) 1202 study and compared between patients developing chronic GVHD and those not developing chronic GVHD within 12 months of transplantation. ADA2 and its relationships with 219 previously measured plasma-soluble proteins, metabolites, and immune cell populations were evaluated as well. Plasma ADA2 enzyme activity was significantly elevated in pediatric HSCT recipients at the onset of chronic GVHD compared to patients without chronic GVHD and was not associated with prior history of acute GVHD or generalized inflammation as measured by C-reactive protein concentration. ADA2-specific enzyme activity met our criteria as a potential diagnostic biomarker of chronic GVHD (effect ratio ≥1.30 or ≤.75; area under the receiver operating characteristic curve ≥.60; P < .05) and was positively associated with markers of immune activation previously identified in pediatric chronic GVHD patients. These results support the potential of ADA2 enzyme activity, in combination with other biomarkers and subject to future validation, to aid the diagnosis of chronic GVHD in children post-HSCT.

Statin-based endothelial prophylaxis and outcome after allogeneic stem cell transplantation

BACKGROUND

Allogeneic haematopoietic stem cell transplantation (alloSCT) often remains the only curative therapy for hematologic malignancies. Although the management of transplant-associated adverse events considerably improved over the last decades, nonrelapse mortality (NRM) remains a challenge, and endothelial dysfunction was identified as a major contributor to NRM.

METHODS

Statin-based endothelial prophylaxis (SEP) has been implemented in the standard of care in our transplant centre to reduce NRM caused by endothelial injury. Here, we retrospectively analysed the impact of SEP on clinical outcome in a cohort of 347 alloSCT patients.

RESULTS

SEP (n = 209) was associated with significantly reduced NRM (hazard ratio 0.61, 95% CI 0.38-0.96) and better overall survival (OS) after acute graft-versus-host disease (HR 0.59, 95% CI 0.37-0.93). Subgroup analyses showed that the NRM benefit was mainly found in patients with an intermediate endothelial activation and stress index (EASIX), while relapse risk was not affected. On day 100 post-alloSCT, patients receiving SEP had significantly higher levels of the rate-limiting enzyme of tryptophan metabolism, indoleamine 2,3-dioxygenase (IDO), higher kynurenine to tryptophan ratios as a proxy of IDO activity and tended to have lower levels of the endothelial injury marker ST2 (p = .055). No significant differences in interferon-gamma or IL18 levels were observed. These biomarker signatures suggest that the beneficial effects of SEP might be mediated by both endothelial protection and immunomodulation.

CONCLUSIONS

Together, these data suggest that SEP improves NRM and OS post-alloSCT in particular in patients with intermediate endothelial risk and provide first mechanistic clues about its potential mode of action.

Current Definitions and Clinical Implications of Biomarkers in Graft-versus-Host Disease

Hematopoietic cell transplantation (HCT) is a potentially curative treatment for many hematologic and nonhematologic disorders. Graft-versus-host-disease (GVHD) in its acute or chronic form remains the most important nonrelapse post-HCT complication. Biomarkers offer objective, unbiased information on systemic disorders, and significant attention has focused on identifying biomarkers for GVHD. Ideally, a GVHD biomarker is actionable, with the results of biomarker testing used to guide clinical management of disease and clinical trial design. Although many GVHD biomarkers have been identified, none have been properly qualified for clinical use. The National Institutes of Health (NIH) and Food and Drug Administration (FDA) have provided biomarker subtype definitions; however, confusion remains about the proper definition and application of these subtypes in the HCT field. The 2014 NIH consensus development project provided a framework for the development of biomarkers for clinical practice. This review aims to clarify the biomarker subtype definitions and reemphasize the developmental framework. Armed with this knowledge, clinicians can properly translate GVHD biomarkers for clinical use.

Humoral Responses and Chronic GVHD Exacerbation after COVID-19 Vaccination Post Allogeneic Stem Cell Transplantation

The COVID-19 pandemic threatens patients with a compromised immune and endothelial system, including patients who underwent allogeneic stem cell transplantation (alloSCT). Thus, there is an unmet need for optimizing vaccination management in this high-risk cohort. Here, we monitored antibodies against SARS-CoV-2 spike protein (anti-S1) in 167 vaccinated alloSCT patients. Humoral immune responses were detectable in 81% of patients after two vaccinations with either mRNA-, vector-based, or heterologous regimens. Age, B-cell counts, time interval from vaccination, and the type of vaccine determined antibody titres in patients without systemic immunosuppression (sIS). Similar to a healthy control cohort, mRNA vaccine-based regimens induced higher titres than vector-based vaccines. Patients on two or more immunosuppressants rarely developed immunity. In contrast, 62% and 45% of patients without or on only one immunosuppressant, respectively, showed a strong humoral vaccination response (titre > 100). Exacerbation of cGVHD upon vaccination was observed in 6% of all patients and in 22% of patients receiving immunosuppression for cGVHD. cGVHD exacerbation and low antibody titres were both associated with higher angiopoietin-2 (ANG2) serum levels. In conclusion, mRNA-based vaccines elicit strong humoral responses in alloSCT patients in the absence of double sIS. Biomarkers such as ANG2 might help with weighing cGVHD risk versus beneficial responses.

Kynurenine pathway activation and deviation to anthranilic and kynurenic acid in fibrosing chronic graft-versus-host disease

Fibrosing chronic graft-versus-host disease (cGVHD) is a debilitating complication of allogeneic stem cell transplantation (alloSCT). A driver of fibrosis is the kynurenine (Kyn) pathway, and Kyn metabolism patterns and cytokines may influence cGVHD severity and manifestation (fibrosing versus gastrointestinal [GI] cGVHD). Using a liquid chromatography-tandem mass spectrometry approach on sera obtained from 425 patients with allografts, we identified high CXCL9, high indoleamine-2,3-dioxygenase (IDO) activity, and an activated Kyn pathway as common characteristics in all cGVHD subtypes. Specific Kyn metabolism patterns could be identified for non-severe cGVHD, severe GI cGVHD, and fibrosing cGVHD, respectively. Specifically, fibrosing cGVHD was associated with a distinct pathway shift toward anthranilic and kynurenic acid, correlating with reduced activity of the vitamin-B2-dependent kynurenine monooxygenase, low vitamin B6, and increased interleukin-18. The Kyn metabolite signature is a candidate biomarker for severe fibrosing cGVHD and provides a rationale for translational trials on prophylactic vitamin B2/B6 supplementation for cGVHD prevention.

High IDO activity and an activated Kyn pathway are common in all cGVHD subtypes

Specific Kyn metabolism patterns were identified for gastrointestinal and fibrosing cGVHD

A pathway shift toward anthranilic and kynurenic acid was found in fibrosing cGVHD

A rationale for vitamin B2/B6 adjustment for cGVHD prevention is presented

Polymorphisms in CXCR3 ligands predict early CXCL9 recovery and severe chronic GVHD

Chronic graft-versus-host disease (cGVHD) is a major cause of mortality and morbidity after allogeneic stem cell transplantation (alloSCT). The individual risk of severe cGVHD remains difficult to predict and may involve CXCR3 ligands. This study investigated the role of single-nucleotide polymorphisms (SNPs) of CXCL4, CXCL9, CXCL10, and CXCL11, and their day +28 serum levels, in cGVHD pathogenesis. Eighteen CXCR3 and CXCL4, CXCL9-11 SNPs as well as peri-transplant CXCL9-11 serum levels were analyzed in 688 patients without (training cohort; n = 287) or with statin-based endothelial protection cohort (n = 401). Clinical outcomes were correlated to serum levels and SNP status. Significant polymorphisms were further analyzed by luciferase reporter assays. Findings were validated in an independent cohort (n = 202). A combined genetic risk comprising four CXCR3 ligand SNPs was significantly associated with increased risk of severe cGVHD in both training cohort (hazard ratio (HR) 2.48, 95% confidence interval (CI) 1.33-4.64, P = 0.004) and validation cohort (HR 2.95, 95% CI 1.56-5.58, P = 0.001). In reporter assays, significantly reduced suppressive effects of calcineurin inhibitors in constructs with variant alleles of rs884304 (P < 0.001) and rs884004 (P < 0.001) were observed. CXCL9 serum levels at day +28 after alloSCT correlated with both genetic risk and risk of severe cGVHD (HR 1.38, 95% CI 1.10-1.73, P = 0.006). This study identifies patients with high genetic risk to develop severe cGVHD.