Steroid-refractory Graft-versus-host Disease Research Articles

Ruxolitinib for the treatment of acute and chronic graft-versus-host disease in children: a systematic review and individual patient data meta-analysis.

Steroid-refractory graft-versus-host disease (SR-GvHD) represents a major complication of pediatric allogenic hematopoietic stem cell transplantation. Ruxolitinib, a selective JAK 1-2 inhibitor, showed promising results in the treatment of SR-GvHD in adult trial, including patients >12 years old. This systematic review aims to evaluate ruxolitinib use for SR-GvHD in the pediatric population. Among the 12 studies included, ruxolitinib administration presented slight differences. Overall response rate (ORR) ranged from 45% to 100% in both acute and chronic GvHD. Complete response rates (CR) varied from 9% to 67% and from 0% to 28% in aGvHD and cGvHD, respectively. Individual-patient meta-analysis from 108 children under 12 years showed an ORR and CR for aGvHD of 74% and 56%, respectively, while in cGvHD ORR was 78% but with only 11% achieving CR. Treatment-related toxicities were observed in 20% of patients, including cytopenia, liver toxicity, and infections. Age, weight, graft source, previous lines of therapy, and dose did not significantly predict response, while a higher rate of toxicities was observed in aGvHD patients. In conclusion, ruxolitinib shows promising results in the treatment of SR-GvHD in children, including those under 12 years. Specific pediatric perspective trials are currently ongoing to definitely assess its efficacy and safety.

Ruxolitinib Pharmacokinetics and Pharmacodynamics in Children with Acute and Chronic Graft-versus-Host Disease

IntroductionWe report pharmacokinetics of oral ruxolitinib in children with steroid refractory acute graft versus host disease (GVHD) (<12y) and chronic GVHD (≤18y) using our published pediatric dosing. MethodsPK sampling before and +2 hours after ruxolitinib was performed in patients with established chronic GVHD. More extensive PK analysis was evaluated in patients with newly diagnosed acute or chronic GVHD before, +0.5, 1, 2, 4 and 6 hours after ruxolitinib in patients >10kg, and before, +3 and +6 hours in children <10kg. We measured pSTAT1, 3 and 5 expression on CD4+ and CD8+ T-cells before and 2 hours after ruxolitinib as a pharmacodynamic marker of JAK/STAT inhibition. ResultsThirteen patients were prospectively enrolled (0-≤18y with existing chronic GVHD(n=8), 0-<12y with new onset steroid refractory acute GVHD(n=4) and newly diagnosed steroid-refractory chronic GVHD(n=1). A large variability in PK was seen. Mean oral clearance (CL/F) was 7.76 ± 4.09 L/h (±SD 4.4; range: 3.1-15.3). The average elimination half-life was 2.32 hours (±SD 1.0). Ruxolitinib clearance was higher in children <2 years versus >2 years (12.1 ± 3.0, vs 5.7 ± 2.8 L/h, p=0.005) and was reduced with concurrent azoles and azithromycin. We saw a variable reduction in pSTAT1/3/5 expression on T-cells at time of peak ruxolitinib absorption (2 hours after dose). ConclusionsChildren<10 kg have lower ruxolitinib exposure, possibly due to inherent increased drug clearance or variabilities in dosing methods leading to decreased drug absorption.

Corticosteroids impair epithelial regeneration in immune-mediated intestinal damage.

Corticosteroid treatment (CST) failure is associated with poor outcomes for patients with gastrointestinal (GI) graft-versus-host disease (GVHD). CST is intended to target the immune system, but the glucocorticoid receptor (GR) is widely expressed, including within the intestines, where its effects are poorly understood. Here, we report that corticosteroids (CS) directly targeted intestinal epithelium, potentially worsening immune-mediated GI damage. CS administered to mice in vivo and intestinal organoid cultures ex vivo reduced epithelial proliferation. Following irradiation, immediate CST mitigated GI damage but delayed treatment attenuated regeneration and exacerbated damage. In a murine steroid-refractory (SR) GVHD model, CST impaired epithelial regeneration, worsened crypt loss, and reduced intestinal stem cell (ISC) frequencies. CST also exacerbated immune-mediated damage in organoid cultures with SR, GR-deficient T cells or IFN-γ. These findings correlated with CS-dependent changes in apoptosis-related gene expression and STAT3-related epithelial proliferation. Conversely, IL-22 administration enhanced STAT3 activity and overcame CS-mediated attenuation of regeneration, reducing crypt loss and promoting ISC expansion in steroid-treated mice with GVHD. Therefore, CST has the potential to exacerbate GI damage if it fails to control the damage-inducing immune response, but this risk may be countered by strategies augmenting epithelial regeneration, thus providing a rationale for clinical approaches combining such tissue-targeted therapies with immunosuppression.

Janus kinase inhibition in the treatment and prevention of graft-versus-host disease.

Graft-versus-host disease (GVHD) is a significant cause of morbidity and mortality after allogeneic hematopoietic stem cell transplantation (HSCT). For many years, corticosteroids have been the mainstay treatment for GVHD, but cases of steroid-refractory GVHD and the severe adverse effects of high-dose corticosteroids have increased the need for preventative and therapeutic strategies for GVHD. Due to the nature of alloreactive T cells, GVHD is inherently linked to the graft-versus-leukemia (GVL) effect, the therapeutic driving force behind stem cell transplantation. A considerable clinical challenge is to preserve GVL while suppressing GVHD. The field of GVHD research has greatly expanded over the past decades, including advancements in T cell modulation and depletion, antibody therapies, chemotherapeutics, cellular therapies, and Janus kinase inhibition. In this review, we discuss current approaches and advances in the prophylaxis and treatment of GVHD with a focus on new emerging advancements in Janus kinase inhibitor therapy.

Late transplant-associated thrombotic microangiopathy verified in bone marrow biopsy specimens is associated with chronic GVHD and viral infections.

To describe late transplant-associated thrombotic microangiopathy (TA-TMA) as chronic endothelial complication in bone marrow (BM) after allogeneic hematopoietic stem cell transplantation (HSCT). BM specimens along with conventional diagnostic parameters were assessed in 14 single-institutional patients with late TA-TMA (more than 100 days after HCST), including 11 late with history of early TA-TMA, 10 with early TA-TMA (within 100 days), and 12 non TA-TMA patients. Three non-HSCT patients served as control. The time points of BM biopsy were +1086, +798, +396, and +363 days after HSCT, respectively. Late TA-TMA patients showed an increase of CD34+ and von Willebrand Factor (VWF)+ microvascular endothelial cells with atypical VWF+ conglomerates forming thickened VWF+ plaque sinus in the BM compared to patients without late TA-TMA and non-HSCT. Severe chronic (p = .002), steroid-refractory GVHD (p = .007) and reactivation of HHV6 (p = .002), EBV (p = .003), and adenovirus (p = .005) were pronounced in late TA-TMA. Overall and relapse-free survival were shorter in late TA-TMA than in patients without late TA-TMA (5-year OS and RFS: 78.6% vs. 90.2%, 71.4% vs. 86.4%, respectively). Chronic allo-immune microangiopathy in BM associated with chronic, steroid-refractory GVHD and/or viral infections are key findings of late, high-risk TA-TMA, which deserves clinical attention.

ECP versus ruxolitinib in steroid-refractory chronic GVHD – a retrospective study by the EBMT transplant complications working party

Ruxolitinib has become the new standard of care for steroid-refractory and steroid-dependent chronic GVHD (SR-cGVHD). Our aim was to collect comparative data between ruxolitinib and extracorporeal photophoresis (ECP). We asked EBMT centers if they were willing to provide detailed information on GVHD grading, -therapy, -dosing, -response and complications for each included patient. 31 centers responded positively and we included all patients between 1/2017-7/2019 treated with ECP or ruxolitinib for moderate or severe SR-cGVHD. We identified 84 and 57 patients with ECP and ruxolitinib, respectively. We performed multivariate analyses adjusted on grading and type of SR-cGVHD (steroid dependent vs. refractory vs. intolerant to steroids). At day+180 after initiation of treatment for SR-cGVHD the odds ratio in the ruxolitinib group to achieve overall response vs. the ECP group was 1.35 (95% CI = [0.64; 2.91], p = 0.43). In line, we detected no statistically significant differences in overall survival, progression-free survival, non-relapse mortality and relapse incidence. The clinical significance is limited by the retrospective study design and the current data can’t replace prospective studies on ECP in SR-cGVHD. However, the present results contribute to the accumulating evidence on ECP as an effective treatment option in SR-cGVHD.

ECP versus ruxolitinib in steroid-refractory acute GVHD - a retrospective study by the EBMT transplant complications working party.

Extracorporal Photophoresis (ECP) is in clinical use for steroid-refractory and steroid-dependent acute GVHD (SR-aGVHD). Based on recent Phase-III study results, ruxolitinib has become the new standard of care for SR-aGVHD. Our aim was to collect comparative data between ruxolitinib and ECP in SR-aGVHD in order to improve the evidence base for clinical decision making. We asked EBMT centers if they were willing to participate in this study by completing a data form (Med-C) with detailed information on GVHD grading, -therapy, -dosing, -response and complications for each included patient. 31 centers responded positively (14%) and we included all patients receiving alloSCT between 1/2017-7/2019 and treated with ECP or ruxolitinib for SR-aGVHD grades II-IV from these centers. We identified 53 and 40 patients with grades II-IV SR-aGVHD who were treated with ECP and ruxolitinib, respectively. We performed multivariate analyses adjusted on grading and type of SR-aGVHD (steroid dependent vs. refractory). At day+90 after initiation of treatment for SR-aGVHD we found no statistically significant differences in overall response. The odds ratio in the ruxolitinib group to achieve overall response vs. the ECP group was 1.13 (95% CI = [0.41; 3.22], p = 0.81). In line, we detected no statistically significant differences in overall survival, progression-free survival, non-relapse mortality and relapse incidence. The clinical significance is limited by the retrospective study design and the current data can't replace prospective studies on ECP in SR-aGVHD. However, the present results contribute to the accumulating evidence on ECP as an effective treatment option in SR-aGVHD.

Novel Pharmacological Treatment Options of Steroid-Refractory Graft-versus-Host Disease

Background. Graft-versus-host disease (GVHD) is a potentially fatal complication of allogeneic hematopoietic stem cell transplant. The mainstay of treatment is corticosteroids, which are ineffective in 30–50% of cases. Steroid-refractory GVHD (SR-GVHD) confers a poor prognosis, with high mortality rates despite appropriate therapy. While there is no reliable treatment for SR-GVHD, a variety of novel therapeutic options are slowly emerging and have yet to be examined simultaneously. Objectives. This review evaluates the potential of novel therapeutic options, as well as their efficacy and safety, for the treatment of SR-GVHD. Study Design. The literature search was conducted in PubMed, Cochrane, and Embase, employing MeSH terms and keywords. The studies had to be prospective phases 1, 2, or 3. We excluded retrospective and nonoriginal studies. Results. While the only approved drug for acute GVHD is ruxolitinib with an impressive overall response rate of 73.2% and a complete response of 56.3%, several monoclonal antibodies and other agents are currently under investigation, offering promising results. These include anti-CD2, anti-CD147, IL-2 antagonist, a mixture of anti-CD3 and anti-CD7 antibodies, anti-CD25, monoclonal antibody to a4b7 on T-cells, anti-CD26, pentostatin, sirolimus, denileukin diftitox, infliximab, itacitinib, and alpha-1 antitripsin. However, the toxicities associated with these novel drugs need further investigation. For chronic GVHD, approved options include ruxolitinib with an ORR of up to 62%, ibrutinib with an ORR of up to 77%, and belumosudil with an ORR of up to 77%. Meanwhile, emerging treatments include tyrosine kinase inhibitors such as nilotinib, rituximab, and low-dose IL-2, as well as axatilimab and pomalidomide. Conclusion. While their efficacy needs to be better evaluated through large-scale, multicenter, randomized clinical trials, these novel agents show potential and could provide a better alternative for SR-GVHD treatment in the future.

Update on the Use of Mesenchymal Stem Cells and their Products in Hematopoietic Stem Cell Transplantation

Graft Versus Host Disease (GVHD) is a major limitation to the success of allogeneic Hematopoietic Stem Cell Transplantation (HSCT) as Steroid-Refractory (SR) acute GVHD carries poor prognosis due to the absence of an efficacious second-line therapy. Mesenchymal Stem Cells (MSCs) which have immunosuppressive, immunomodulatory, and regenerative properties may become a highly effective therapeutic modality for SR-GVHD in the near future. MSCs have already been approved to treat childhood SR-GVHD in Japan, and they have been conditionally licensed in New Zealand and Canada. It is expected that MSCs will be approved for the treatment of SR-GVHD in adults in Europe, North America, and other parts of the world within a few years. Utilization of the recently introduced techniques including the use of MSC products such as exosomes and Extracellular Vesicles (ECVs) instead of the parent MSCs, robotic manufacturing technology, and genetic engineering of MSCs will ultimately overcome the remaining obstacles facing the widespread utilization of MSCs and their products as therapeutics not only in HSCT but also in other medical fields. The aim of this review is to provide an update on the remarkable progress achieved in the use of MSCs and their products in the field of HSCT.

Patterns of Graft-Versus-Host Disease (GvHD) Prevention and Management in the Eastern Mediterranean (EM) Region: A Worldwide Network for Blood & Marrow Transplantation (WBMT) Survey

Introduction: GvHD is a significant cause of morbidity and mortality in recipients of allogeneic hematopoietic cell transplant (HCT). The prevention, management, and treatment of GvHD vary in different regions worldwide. This WBMT study aims to better understand the current clinical practices of GvHD prevention and management around the globe. This study presents our survey results in the Eastern Mediterranean Region. Methodology: This is a cross-sectional survey-based study involving hematopoietic cell transplant (HCT) centers in the EM region. Participants of the survey were programs' directors or their designees. The survey comprised two parts; the first part aimed to study the practices of GvHD prevention, whereas the second part aimed to study GvHD management and treatment. The survey was distributed and filled out between December 2022 and May 2023. Results: Thirty participants from 28 institutions responded. Participants were from eleven different countries in the EM region. Fourteen participants (50%) filled it for combined pediatrics and adult HCT programs. The remaining participants filled it for programs performing HCT, either only in adult (27%) or pediatrics (23%) patients. The majority of participants indicated that cyclosporine and methotrexate combination is the most used GvHD prophylaxis therapy in both myeloablative and reduced intensity HCT in their centers. Cyclosporine was the predominantly used calcineurin inhibitor (CNI), followed by tacrolimus. All centers using cyclosporine indicated that they monitor its level, with 200-300 mcg/L being the target in 66% of the survey. Cyclosporine was typically given for 2-12 months after HCT, with around 80% of centers stopping it at 3-4 months post-HCT in recipients with malignant indications and around 90% of centers stopping it around 6-12 months post-HCT in recipients with non-malignant indications. When tacrolimus is used, results showed that it is typically used for similar duration to cyclosporine. Twenty-nine participants reported using post-transplant cyclophosphamide (PTCy) in their centers, with seven centers (24%) reporting its use in indications other than haploidentical transplants. Additionally, the results show that PTCy is typically used in combination with other medications, with 53% of participants reporting that it is used along with mycophenolate mofetil and cyclosporine and only one participant reported its use as a single agent. Seven participants (23%) reported that PTCy is typically used in doses less than 50 mg/kg. In patients with established GvHD, steroids were most commonly used alone as a first-line therapy in acute and chronic GvHD. The majority of centers report re-introducing or continuing the immunosuppressive agent used in GvHD prevention, with few centers indicating that they switched to another CNI. 64% and 55% of centers indicated that they have a standard-operating procedure (SOP) for steroid-refractory acute GvHD (aGvHD) and chronic GvHD (cGvHD), respectively. Only two centers reported involving steroid-refractory GvHD patients in clinical trials. Second-line therapy for steroid-refractory aGvHD and cGvHD varies significantly between centers depending on the type of GvHD and organ involved. In steroid-refractory aGvHD, ruxolitinib was the most frequently listed agent to be considered in the second line, regardless of the involved organ. Ruxolitinib was followed by Extracorporeal photopheresis in Skin aGvHD, Budesonide in lower GI tract aGVHD, and Mycophenolate Mofetil in liver aGvHD. In cGvHD, ruxolitinib was also the most frequently listed medication. However, more significant variability between centers was noted in treating organ-specific cGvHD. Conclusion: GvHD prevention and management practices vary between the different EM region centers. Some variations could be related to access to some medications. This might indicate the need for more evidence-based practices in preventing and managing GvHD and possibly adjusting the guidelines according to access and availability of some medications. WBMT is currently working on understanding the global patterns of GvHD practices in other regions and, ultimately, a global comparative study of all data combined.

Efficacy and Safety of Fecal Microbiota Transplantation in the Treatment of Chronic Steroid-Refractory Graft-Versus-Host Disease after Hematopoietic Stem Cell Transplantation

Efficacy and safety of fecal microbiota transplantation in the treatment of chronic steroid-refractory graft-versus-host disease after hematopoietic stem cell transplantation Introduction The majority of patients who undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT) with acute gut graft-versus-host disease has lost the diversity of gastrointestinal microbiota and associated to adverse clinical outcome. Despite glucocorticoids treatment has been considered as the first-line therapy regardless acute or chronic GVHD, the curative efficiency and durable response remains unsatisfactory. Several studies suggesting that fecal microbiota transplantation (FMT) from healthy donor effectively alleviated gut steroid-refractory acute GVHD (SR-aGVHD) by restoring diversity of gastrointestinal microbiota, resistance to potential pathogens, and transforming essential materials to metabolites for immunomodulating donor T cell which improved clinical outcomes in allo-HSCT. However, it is still unclear whether FMT therapy have similar potential efficacy in treating steroid-refractory chronic GVHD (SR-cGVHD). Here, we report the results of a pilot study from our single center using FMT from unrelated healthy donor to treat patients with SR-cGVHD. Method 12 patients aged 16-60 years with SR-cGVHD after allo-HSCT were enrolled. A total of 31 FMTs were performed via colonoscopy in 12 patients with SR-GvHD over three consecutive months. Adverse events with reasonable suspicion for being associated with FMT were monitored after treatment for 28 days. Partial response was defined as a decrease at least one stage in severity of GVHD or able to taper steroid dose. No response was defined as unable to taper steroid dose or need to increase or add immunosuppressor for controlling GVHD progression. CR was defined as the complete resolution of GVHD manifestations in all organs. To characterize the impact of the FMT on the gut microbiota, stool samples from recipients were collected the day before FMT treatment and 4 weeks after FMT treatment then carried out 16s rRNA sequencing. Result The overall response rate (ORR) in the patients with SR-cGvHD reached 50% (6/12), including CR in 0/0 (0%) cases and PR in 6/12 (50%). Most common adverse events were 3 abdominal bloating (9.68%), 2 diarrhea cases (6.45%) and 1 fever (3.23%). No serious adverse events were observed. The diversity of gastrointestinal microbiota remarkable decreased during SR-GVHD and it recovered after FMT (Figure B). After FMT treatment, similar α diversity of gastrointestinal microbiota in PR and NR patients was observed, whereas β-diversity analysis showed significant differences in the composition and abundance of the bacterial colonization between groups (Figure C and D). Conclusion The present study indicates that FMT as a new potential therapy in the treatment of SR-cGvHD is safe, well tolerated, and effective. Disclosures No relevant conflicts of interest to declare.

A Novel, Closed-Line Mini Extracorporeal Photopheresis (ECP) Technique Using the Therakos TM CellEx TM Photopheresis System, Developed for Patients with Contraindications Against Conventional ECP Therapy

Introduction: Conventional ECP has proven efficacy for treating several diseases, most significantly steroid-refractory chronic GVHD. Unfortunately, body weight and sufficient venous access limit the availability of this treatment modality. Children, in particular, usually have limited access to ECP. A simplified mini buffy coat ECP technique that allows treating small children and patients with apheresis contraindications has been tested in selected cases during the last 20 years. However, this method relies on an open-line system that requires a longer time and a cell processing laboratory, making this approach challenging. A new -closed-line- method, using the Therakos TM CellEx TM Photopheresis System, has been developed and evaluated in our Center. This method requires no processing laboratory or other special equipment and takes only 60-120 minutes, making the procedure potentially usable in routine practice. Design and methods: A 7-year-old girl had been treated at our Pediatric Bone Marrow Transplantation Unit with grade IV chronic steroid-refractory GVHD (skin, and less severe liver involvement). As all other options were exhausted, ECP became a desirable form of treatment. However, the patient's low body weight and serious venous access problems hindered conventional ECP treatment. We developed a solution that requires 200-250 ml whole blood collection from the patient, takes less than 2 hours, does not need special cell processing equipment, and allows the ECP treatment to commence in the form of a regular autotransfusion. Consent forms were obtained from the patient's caregivers as well as from the local Ethical Committe. The patient's age at the start of treatment was seven years, and her body weight was 28 kg. A total of 17 mini-ECPs were performed weekly up until the submission of this abstract, and the number of treatments per patient was 33. The duration of mini-ECP treatment has been five months. 5 to 8 mL/kg of whole blood was drawn from the patient. Separation of the white blood cell (WBC) rich buffy coat of the patient's blood - with donor blood product supplementation as needed - was performed through an individualized use of the CellEx TM photopheresis kit and blood prime program. The buffy coat was ultraviolet A (UVA)-irradiated after adding 8-methoxypsoralen (8-MOP) within the Therakos TM CellEx TM Photopheresis System and divided into two fractions under a laminar air flow cabinet. The autologous residual blood with the first fraction of the UVA irradiated buffy coat was transfused immediately. The second buffy coat fraction was stored at 4 °C and transfused the following morning through a peripheral vein. Results : The median volume of the collected whole blood was 250 mL (203-250 mL). The median volume was 72 ml (48-88 mL) for the first fraction of the irradiated buffy coat and 71 ml for the second fraction (48- 88 mL). Apoptosis and cell death were analyzed by annexin V staining; apoptosis and lymphocyte proliferation was measured by flow cytometry. UVA irradiation of the 8-MOP infused buffy coat resulted in significant induction of WBC apoptosis at 24 hours. No clinical side effects were observed during mini ECP treatment; all microbiological control tests were negative. Partial response was observed within three months (skin), and the tapering of systemic immunosuppression (methylprednisolone and ruxolitinib) began at five months. Conclusion: Mini whole blood ECP induces apoptosis and lymphocyte proliferation inhibition, both occurring after standard ECP. The closed-line method requires no special equipment and is not demanding for the patient, providing a viable solution to the technical difficulties children with the need for ECP treatment face.

IFNγ Primed MSCs Suppress Stimulated T Cells By Inducing Perturbations of Redox Homeostasis

Acute Graft versus host disease (GVHD) remains the primary cause of morbidity and nonrelapse mortality after allogeneic hematopoietic cell transplantation (HCT). Despite the current standard prophylaxis, approximately 50% of patients will develop acute GVHD. the outcome of patients with steroid-refractory and/or severe GVHD is poor; hence, more effective prophylaxis reducing the risk of these scenarios is greatly needed. In recent years, considerable attention has been directed toward mesenchymal stromal cells (MSCs) as prophylaxis and therapy for acute GVHD. Even though the immunosuppressive and immunomodulatory properties of MSCs are enhanced by proinflammatory cytokines such as interferon γ (γMSCs), relatively less attention has been focused on these cells. Our laboratory has shown human γMSCs are effective in GVHD prophylaxis in a fully mismatched murine HCT/GVHD model. When infused IV on day +1 after HCT, γMSCs traffic to the spleen, liver, and gut-associated lymphoid tissue (GALT) which is essential for effective prophylaxis. This may be a key element of the mechanism of prophylaxis as the gut and GALT are thought to be paramount for the development of GVHD. We now sought to understand the mechanism(s) of γMSC suppression of alloreactive T cells suppressive activity in this specific clinical and biological setting. In vivo, control mice transplanted with a fully MHC mismatched graft developed GVHD in 6-8 days (0% GVHD-free survival) while human γMSCs administration at day +1 completely prevented GVHD in the first 17 days (100% GVHD survival) but the animals developed acute GVHD in 21-28 days. Hence, a single dose of γMSCs is 100% effective early but is insufficient for overall GVHD prevention. The mechanism is highly effective but of relatively short duration, and seemingly reversible. In vitro, the reversible T cell suppressive activity was entirely contact-independent, while cell-to-cell contact could induce T cell death. Moreover, γMSC IDO1 expression, alone, was sufficient to suppress T cells. After 24 hours of T cell activation or γMSC suppression in vitro, we found the T cells were arrested in G0 inconsistent with most cell cycle regulation which would arrest cells in late G1 at the so-called restriction point. In scRNA Seq, we identified 16,478 expressed genes in both groups but only 98 genes were significantly differentially expressed (≥20% FC, Padj ≤ 10 -4). ROS response pathways were significantly enriched in the suppressed cells suggesting oxidative stress. Paradoxically, flow cytometric analysis of CM-H2DCFDA stained T cells revealed less ROS in suppressed cells compared to controls. Additionally, total NAD is elevated and the NAD/NADH ratio was 10-fold less in suppressed T cells compared to activated cells indicating an excess of reducing equivalents in the suppressed cells. Collectively these data define reductive stress. On this note, the upregulation of ROS response genes is also consistent with reductive stress. IDO1 activity seems to have induced reductive stress. The IDO1 catalytic activity converts tryptophan (Trp) to kynurenine (Kyn). We then found the addition of Trp (10 µM) to γMSC CM abolished suppression; supplementing fresh media with 15-fold excess Kyn had no effect. Moreover, RPMI without Trp and with dialyzed FBS also conferred suppression to activated T cells. These data suggest that among the many metabolites consumed or generated in γMSC CM, the lack of Trp induces T cell suppression. Trp supplementation of γMSC CM showed the expected level of ROS in activated T cells suggesting the Trp deficiency caused the reduced ROS. Supplementing γMSC CM with a graded concentration of hydrogen peroxide, we found that 100 nM hydrogen peroxide was not toxic to control cells, had ROS similar to activated T cells, and abolished suppression indicating the reduced ROS directly caused suppression. Kyn, nutritional deficiency, or an integrated stress response did not seem to play a measurable role in this setting. Collectively, our data suggest that IDO1-mediated Trp deficiency perturbs redox homeostasis (reductive stress) which suppresses activated T cells. We postulate that once redox homeostasis is restored, T cell activation proceeds. Future efforts will be directed toward identifying the link between Trp deficiency and redox homeostasis in this setting, and the genomic changes that directly mediate the lack of T cell proliferation.

Inhibition of Bromodomain and Extraterminal Domain (BET) Proteins Alleviates Chronic Graft- Versus-Host-Disease Via Modulating the CXCR5/CXCL13 Axis

Introduction: Chronic graft-versus-host disease (cGVHD) is a severe complication of allogeneic hematopoietic cell transplant (allo-HCT) often leading to transplant-mediated mortality. Studies have shown that T follicular helper cells (Tfh) upregulate CXCR5 and migrate into the lymphoid organ follicles in response to CXCL13 promoting germinal center (GC) B cell proliferation and differentiation of plasma cells resulting in pathogenic antibody production and profibrotic pathways associated with cGVHD. In contrast, T follicular regulatory cells (Tfr) modulate the magnitude of the GC response; thus, the balance of Tfr/Tfh could be crucial to mitigating cGVHD.Bromodomain and extra-terminal domain (BET) proteins are epigenetic readers influencing transcription of a multitude of inflammatory genes and our lab has previously reported pharmacological inhibition of BET, through OPN-51107, improves survivability and limits disease progression in murine models of acute GVHD that led to opening the first-in-human clinical trial of OPN-51107 in steroid refractory acute GVHD. We demonstrated BET proteins to be important in modulating acute GVHD pathogenesis, however, mechanisms of BET regulation within cGVHD are largely unknown. Here, using OPN-51107 we aim to further investigate mechanisms of cGVHD pathogenesis and identify successful BET inhibition-based therapeutic approaches. Methods: We used a Bronchiolitis Obliterans model (B6-&amp;gt;B10.br) of cGVHD. Mice were administered 120mg/kg cyclophosphamide (D-3 and D-2) and 8Gy irradiation (D-1) as a conditioning regimen followed by B6 T-cell depleted bone marrow cells with and without CD45.1 B6 splenocytes. Mice that did not receive allogeneic splenocytes served as controls and did not develop GVHD. Recipients of allogeneic splenocytes were treated with a BET inhibitor - OPN-51107 at 10mg/kg 3x/weekly, or vehicle, from D28-54(+ 4) via oral gavage. Resting lung elastance and resistance was measured using the Flexivent system. At the time of lung function analysis, lung and liver tissue was harvested and stained via Hesson's Trichrome to identify and quantify collagen deposition. We performed immunofluorescence to quantify alveolar alloantibody deposition. Spleen and lung cells were stimulated with PMA/I and analyzed via spectral flow cytometry. An inflammatory murine cytokine array (#ARY006, R&amp;D Systems) was used to analyze circulating plasma cytokine levels. Results: BET inhibition via OPN-51107 treatment decreased lung resistance (vehicle vs OPN-51107 =1.16Rrs vs 0.83Rrs p&amp;lt;0.05) and elastance (vehicle vs. OPN-51107=62Ers vs. 45Ers p&amp;lt;0.05). OPN-51107 treatment also significantly reduced alveolar antibody (Ig) deposition per area compared to vehicle (vehicle vs. OPN-51107= 4.91% vs. 3.3% p=0.01) and collagen deposition (vehicle vs. OPN-51107=19.0% vs. 12.9% p&amp;lt;0.05) and liver (vehicle vs. OPN-51107=19.3% vs. 2.35% p&amp;lt;0.0001). Congruently, BET inhibition decreased B220-CD19- CD138+mature plasma cells (vehicle vs. OPN-51107=15% vs 9.1% p&amp;lt;0.05) in the lung. Serum cytokine array analysis revealed a significant decrease in circulating CXCL13, relevant to Tfh migration as well as a decrease in other proinflammatory cytokines - CXCL9, MCP-1, IL3, RANTES and G-CSF important for macrophage activation and pathogenicity in OPN-51107 compared to vehicle treated mice. BET inhibition reduced splenic Tfh while increasing Tfr, thereby increasing Tfr:Tfh ratio (vehicle vs. OPN-51107= 5% vs. 9% p&amp;lt;0.05). Furthermore, total splenic CD19+ B-cells (vehicle vs. OPN51107= 70% vs. 33% p&amp;lt;0.001) as well as CXCR5 expression on B-cells were decreased in OPN-51107 treated mice (MFI vehicle vs. OPN-51107= 4744 vs. 571.5 p&amp;lt;0.0001). Conclusion: OPN-51107 improved lung function which correlated with significantly decreased lung fibrosis and antibody deposition in a BO model of cGVHD. BET inhibition reduces cGVHD immune pathology through decreased inflammatory cytokine production, promotion of GC Tfr cell population and modulates B-cell proliferation and/or trafficking. Significance: Using OPN-51107 in a BO model of cGVHD we demonstrate that BET inhibition is a feasible therapeutic strategy to reduce disease severity and improve lung function.

The MAGIC Algorithm Probability Predicts Long-Term Outcomes and Treatment Response to Second-Line Therapy for Acute Gvhd

Introduction: Risk stratification approaches using clinical criteria or biomarkers in acute graft-versus-host disease (GVHD) have traditionally been implemented at diagnosis or initiation systemic treatment with corticosteroids. For patients who require second-line treatment, the significance of biomarkers at salvage therapy and the relationship between biomarker risk and choice of therapy are unknown. Methods: We studied adult patients who received second-line treatment for acute GVHD between January 2016 and December 2021 in the Mount Sinai Acute GVHD Consortium (MAGIC) database, which collects clinical data and longitudinal serum samples from allogeneic HCT recipients using a rigorous PRoBE study design. Exclusion criteria included relapse of underlying malignant disease prior to second-line therapy, missing response data, or missing serum sample. Serum samples collected from 7 days prior to 3 days after initiation of second-line therapy met criteria for biomarker analysis. The MAGIC algorithm probability (MAP) was calculated as a single value based on concentrations of ST2 and REG3α and was stratified at a threshold of 0.290 to define high MAP and low MAP groups. The primary objective evaluated the association between MAP and survival for patients receiving second-line therapy for acute GVHD. The key secondary objective was to investigate the MAP and choice of second-line systemic agent on Day 28 overall response rate (ORR) and survival. Results: In total, 316 adult patients received second-line treatment for acute GVHD; 149 patients (47%) were excluded for disease relapse (n=27), missing response data (n=48), or missing sample (n=74).Of the 167 evaluable patients, most had steroid-refractory acute GVHD (n=146, 87%), rather than steroid-dependent (n=8, 5%) or steroid-sensitive (n=14, 8%) disease. 62 patients received ruxolitinib while 102 received other systemic agents (best available therapy: BAT). Baseline clinical characteristics of the study population according to treatment choice were similar, except for donor type (Rux: MRD 15%, MUD 74%, haplo 11%; BAT: MRD 30%, MUD 67%, haplo 3%; P=0.014) and median days from corticosteroids to second-line treatment (Rux: 18, BAT: 12; P=0.02).In total, 81 patients had high MAPs and 86 patients had low MAPs, with similar distribution in each treatment cohort (P=0.53). For the entire cohort, the median follow-up for survivors was 22 months (range, 1.5-27).The MAP separated patients into 2 groups (high vs low) with significantly different mortality (NRM at 2 years, 76% vs 29%, P&amp;lt;.0001) and survival (OS at 2 years, 12% vs 63%, P&amp;lt;.0001). Patients who received ruxolitinib as second-line therapy had lower mortality (NRM at 2 years, 35% vs 60%, P&amp;lt;.002) and improved survival (OS at 2 years, 51% vs 32%, P&amp;lt;.008), compared to those who received other systemic agents. However, the outcomes of patients with high MAP were poor, regardless of second-line treatment choice ( Figure 1A). The MAP (low vs high), time from corticosteroids to second-line treatment (≥14 days vs &amp;lt; 14 days), GVHD grade at second-line (0-2 vs 3-4), and choice of second-line therapy (Rux vs BAT) were all significant (P&amp;lt;0.05) predictors of lower NRM and higher OS in multivariate analysis. The MAP also separated patients into 2 groups with significantly different D28 ORR (low: 49%, high: 30%, P&amp;lt;.0001). In agreement with prospective trials, ruxolitinib resulted in higher D28 response rates compared to other systemic therapies (ORR 54.9% vs 30.5%, P=0.005), which was observed in both low MAP (ORR, 64.5% vs 38.5%, P=0.017) and high MAP cohorts (ORR, 42.9% vs 22.6%, P=0.06) ( Figure 1B). The MAP (low vs high), GVHD grade at second line (0-2 vs 3-4), and choice of second-line therapy (Rux vs BAT) were significant predictors (P&amp;lt;0.05) of higher D28 ORR in multivariate analysis. Conclusion: The MAP measured at the initiation of second-line systemic treatment for acute GVHD predicts NRM and OS, as well as treatment response. The outcomes of patients with high MAP are poor, regardless of second-line treatment choice, and the higher CR rate in low MAP patients may drive higher survival rates. Incorporation of MAP into clinical trials in this setting warrants investigation. The results also support the current use of ruxolitinib as second-line treatment for acute GVHD, particularly in patients with low MAP.

Increased Circulating 2-Methylbutyrate Following Fecal Microbiota Transplantation in Patients with Refractory-Chronic Graft-Versus-Host Disease after Allogeneic Hematopoietic Cell Transplantation

Introduction Allogeneic hematopoietic cell transplantation (allo-HCT) is a curative treatment for patients with hematological malignancies. Steroid-refractory chronic GVHD (SR-cGVHD) remains the major cause of non-relapse mortality and life-threatening disease late after allo-HCT. Several groups reported that perturbation in the gut microbiome and impaired production of microbial metabolites such as short chain fatty acids (SFCAs) have involved in cGVHD pathogenesis and severity. Currently, there is no acceptable consensus and no standard second-line treatments for patients with SR-cGVHD. Our pilot study (NCT04622475) using fecal microbiota transplantation (FMT) from healthy donor to treat patients with SR-cGVHD provide a new insight into therapeutic strategies for SR-cGVHD. To investigated whether FMT improves the SR-cGVHD clinical outcome through SCFAs, the measurement of SCFAs concentration was performed in the plasma from SR-cGVHD patients after FMT. Here we report the preliminary results of this study. Method 12 patients aged 16-60 years with SR-cGVHD after allo-HCT were enrolled. A total of 31 FMTs were performed via colonoscopy in 12 patients with SR-cGvHD over three consecutive months. FMT courses were repeated from the same donor. To characterize the impact of the FMT on the gut microbiota, stool samples and plasma from recipients were collected the day before FMT treatment and 4 weeks after each FMT treatment then carried out 16s rRNA sequencing and LC-MS. Complete response was defined as the complete resolution of GVHD manifestations in all organs. Partial response was defined as a decrease at least one stage in severity of GVHD or able to taper steroid dose. No response was defined as unable to taper steroid dose or need to increase or add immunosuppressor for controlling GVHD progression. Result The circulating SCFAs levels of SR-cGVHD patients associated to FMT outcome (Figure A). After FMT, the concentrations of butyric acid, isovaleric acid, valeric acid, 4-Methylvaleric acid and hexanoic acid had a higher trend in the plasma of responders, but not in the non-responders (Figure B). Notably, 2-Methylbutyrate markedly increased in the plasma of responders after FMT, when compared to non-responder after FMT(Figure C). Conclusion The present study indicates that FMT improved SR-cGVHD patients by increasing the circulating SCFAs, particularly 2-Methylbutyrate levels. 2-Methylbutyrate might play a role in FMT therapy for SR-cGVHD. Disclosures No relevant conflicts of interest to declare.

Sequential Umbilical Cord Derived Mesenchymal Stromal Cells (MSCs) for the Third-Line Salvage Treatment of Steroid-Refractory Acute GvHD: A Multicenter, Open Label, Phase 1b/2 Trial

Background and Aim: Acute graft-versus-host disease (aGVHD) is a life-threatening complication after allogeneic hematopoietic stem cell transplantation (allo-HSCT), particularly if treatment is refractory. Human mesenchymal stromal cells (MSCs) have demonstrated safety and efficacy in steroid refractory acute graft versus host disease, due to their well-described immunosuppressive properties, however, clinical trials have resulted in variable success and an optimal source of MSC has yet to be defined. Based on the importance of maternal-fetal interface immune tolerance, the umbilical cord may provide a superior tissue source of MSC to mediate immunomodulation in aGVHD (SR-aGVHD). This study aimed to investigate the safety and efficacy of MSCs delivered as third-line salvage therapy for SR-aGVHD who had received at least two-lines of steroid-containing immunosuppressive therapy. Method: This phase1b/2, multicenter, open-label clinical trial of a third-party, off-the-shelf preparation of human umbilical cord derived mesenchymal stromal cells (hUC-MSCs) (ChiCTR2200061603) enrolled grades II to IV steroid-refractory aGVHD patients who had been treated with at least two-lines of steroid-containing immunosuppressive therapy. This trial consist of 2 parts：a phase Ib dose escalation part using a standard 3+3 design, which planed biweekly i.v. infusions of hUC-MSCs, at 0.5× 10 6 per kg, 1.0× 10 6per kg and 2.0× 10 6 per kg for 3 weeks, to determine the maximum tolerated dose (MTD) and recommended phase 2 dose (RP2D). Phase II of this work is an expansion cohort study of hUC-MSCs at RP2D 1.0×10 6 per kg with 15 patients. The primary endpoint of the study was safety and RP2D. The key secondary endpoints were efficacy of the overall response rate (ORR) at Day 28 and Day 56 defined per the 2014 NIH consensus criteria. Results: From June 23, 2022, through June 12, 2023, a total of 25 patients were enrolled with the median follow up period of 106 (10,210) days. Of the included 25 cases 11 patients (44.0%) were grade III/IV and 14 patients (56.0%) were grade II aGVHD at enrollment. Median patient age was 37.0 (range:24.5-47.0) years, 44.0% male. hUC-MSCs was well tolerated without dose-limiting toxicities in aforementioned three dosages. The reported adverse events (AEs) potentially associated with hUC-MSCs were hypofibrinogenemia (12.0%), upper respiratory tract infection (4.0%), leukopenia (4.0%) and anemia (8.0%) within the median follow-up period of 106 (10, 210) days. Grade 3 or higher AEs were reported in 6 patients (6/25, 24%) with 11 events, all of them were supposed uncorrelated with hUC-MSC. Three patients unfinished the administration:1 was due to withdrawn ICF; 1 was SAE and 1 was due to participate another trial. Up to date of June 12, 2023, twenty of the initial included 25 patients were still in group. And the RP2D of this trial was identified as 1.0× 10 6 per kg. At Day 28, 20 patients (80.0%, 95% CI:59.3%-93.2%) had an overall response, including 10 (40.0%) with complete responses. And at day 56, only one patient loss response, while another non-response patient at day 28 in the dose of 1.0× 10 6 per kg achieved late responses at day 56 ( Table 1). Responses were observed across skin (19/19, 100%), gastrointestinal tract (7/11,72.7%), and liver (2/2, 100.0%) at day 28. Durable overall response at day 56 was 76% (19/25), Figure 1. The median follow-up time after the initiation of hUC-MSC treatment was 106 (10,210) days with the cutoff date of 180 days after recruitment. The probability of 180-day overall survival (OS) and non-relapse mortality was 88.0% (95% CI, 68.8-97.5%) and 8.0% (95% CI, 1.0-26.0%), respectively. The 180-day cumulative incidence of relapse of primary hematologic disease was 8.0% (95%CI,1.0-26.0%). The percentage of total T lymphocyte, neutrophil, cytokine IL-10, IP-10 were statistically decreased in CR group, while CD8+central memory T cell was significantly increased compared to non-CR groups 24h or 96h after hUC-MSC administration (P&amp;lt;0.05）. Conclusion: Collectively, our results support hUC-MSCs as an effective salvage treatment for SR-aGVHD with safe profile. Key words: Acute graft-versus-host disease; allogeneic hematopoietic stem cell transplantation; mesenchymal stromal cells

Efficacy of Treatment Options for Children with Steroid-Refractory Acute Gvhd

Background: Approximately half of patients with acute graft-versus-host disease (aGVHD) after allogeneic hematopoietic cell transplantation (alloHCT) experience steroid-refractory aGVHD (SR-aGVHD) disease. Patients with SR-aGVHD require intense and prolonged immunosuppression resulting in high risk of severe opportunistic infections and risk of relapse of malignancy which ultimately results in significant increase in short- and long-term morbidity and mortality, poor quality of life for children and their families and increases financial burden on families and health care system. Corticosteroids have been the mainstay of therapy for new onset acute GVHD. However, treatment for SR-GVHD in children is a serious unmet need. To date, few therapies have been investigated for SR-aGVHD in robust clinical trials for children. Moreover, long-term benefits and survival data from these trials are often lacking or unclear. A systematic literature review (SLR) was conducted to better understand the efficacy of therapies under investigation in this population. Methods: Literature database searches of Embase, MEDLINE, Cochrane, and Econlit, were performed on 22 May 2023 according to Cochrane guidelines to identify randomized and non-randomized clinical trials in which the pediatric population with SR-aGVHD represented at least 50% of the trial population. Clinical trials extensions and long-term follow-up reports were also included. Studies published in English from 2009 onwards were retrieved. Additional manual searches of relevant conference abstracts published in the past 3 years were performed. Results: Overall, 29 publications (23 unique studies) met the selection criteria, representing a total of 801 patients aged 18 years or younger with SR-aGVHD. A limited number of interventions were investigated in this population and most studies had a non-randomized design (19 out of 23 studies). Overall survival (OS) and response rates (ORR) were analyzed from studies enrolling more than 20 pediatric patients with SR-aGVHD (9 studies, Table), which investigated therapies such as mesenchymal stromal cells (MSC), remestemcel-L (MSC manufactured by Mesoblast), ruxolitinib, etanercept and extracorporeal photopheresis. At least 80% of patients treated with cellular therapies (remestemcel-L/MSC) and etanercept had grade III or IV disease. ORR on day 28 was 92% with etanercept, 77% to 91% with ruxolitinib, 61% to 92% with mesenchymal stromal cells, 61% to 70% with remestemcel-L, and 55% with extracorporeal photopheresis. Durable response rates of 69% at day 56 and 70% at day 100 and were noted for remestemcel-L and ruxolitinib, respectively. OS at 6 months was 69% with remestemcel-L, and 71% with mesenchymal stromal cells. OS at 1 year was reported for remestemcel-L (63%) and etanercept (59%). Long-term survival data beyond 1 year of patients enrolled in the clinical trial was available only for remestemcel-L and showed an OS rate of 51% at 2 years and 49% at 3 and 4 years. 4-year OS probability for patients with grade III or IV (48% in both cases) was similar to that for the overall population. Conclusions: Only a few small size clinical trials were conducted for children with SR-aGVHD which poses a unique challenge for FDA to approve new therapies for SR-aGVHD. Despite a small number (n=9: 5 ruxolitinib arm and 4 control arm) of children (12-18 years) enrolled in REACH II study, ruxolitinib was FDA approved for children&amp;gt;12 years of age. Long-term efficacy outcomes of children enrolled in clinical trials were reported only for remestemcel-L and showed that approximately half survived beyond 3 years. While other reports showed that grade III/IV disease is associated with poorer outcomes compared to grade I/II, similar survival rates were noted for patients with grade II, III and IV treated with remestemcel-L. In children with SR-aGVHD, other therapies such as ruxolitinib or etanercept demonstrated good response rates, however, the associated survival benefit is unclear.

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

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

Ruxolitinib add-on therapy in steroid-refractory graft-vs-host disease following hematopoietic cell transplantation: A single institutional experience

Steroid-refractory graft-vs-host disease (SR-GVHD) remains a significant cause of mortality after allogeneic hematopoietic cell transplantation (HCT), and the trajectory of treatment response for that vary. In our case series, we introduced six cases experiencing SR-GVHD who achieved better disease control after applying ruxolitinib (RUX). Of the six cases, five of them achieved symptoms-free while one of them, unfortunately, died of invasive fungal infection. Three alive cases were weaned off the RUX treatment successfully, while the remaining were on a medication tapering program. We demonstrated mixed efficacy in patients with SR-GVHD, suggesting that the RUX add-on may be a useful therapeutic adjunct in combination with other immunosuppressants.