The Pathophysiology and Treatment of Graft-Versus-Host Disease: Lessons Learnt From Animal Models

Application of novel CAR technologies to improve treatment of autoimmune disease

Chimeric antigen receptor (CAR) T cell therapy has become an important treatment for hematological cancers, and its success has spurred research into CAR T cell therapies for other diseases, including solid tumor cancers and autoimmune diseases. Notably, the development of CAR-based treatments for autoimmune diseases has shown great progress recently. Clinical trials for anti-CD19 and anti-BCMA CAR T cells in treating severe B cell-mediated autoimmune diseases, like systemic lupus erythematosus (SLE), have shown lasting remission thus far. CAR T cells targeting autoreactive T cells are beginning clinical trials for treating T cell mediated autoimmune diseases. Chimeric autoantigen receptor (CAAR) T cells specifically target and eliminate only autoreactive B cells, and they have shown promise in treating mucosal pemphigus vulgaris and MuSK myasthenia gravis. Regulatory CAR T cells have also been developed, which show potential in altering autoimmune affected areas by creating a protective barrier as well as helping decrease inflammation. These new treatments are only the beginning of potential CAR T cell applications in treating autoimmune disease. Novel CAR technologies have been developed that increase the safety, potency, specificity, and efficacy of CAR T cell therapy. Applying these novel modifications to autoimmune CARs has the potential to enhance the efficacy and applicability of CAR therapies to autoimmune disease. This review will detail several recently developed CAR technologies and discuss how their application to autoimmune disease will improve this emerging field. These include logic-gated CARs, soluble protein-secreting CARs, and modular CARs that enable CAR T cell therapies to be more specific, reach a wider span of target cells, be safer for patients, and give a more potent cytotoxic response. Applying these novel CAR technologies to the treatment of autoimmune diseases has the potential to revolutionize this growing application of CAR T cell therapies.

Role of extracorporeal photopheresis in the management of acute and chronic graft versus disease: current status

Extracorporeal photopheresis (ECP) is a therapy that combines the collection of mononuclear cells by apheresis, the addition of a photosensitizer (8-methoxisoralen), the illumination of the product with ultraviolet A light, and the immediate infusion of the product to the patient. Initially developed and approved to treat T-cell cutaneous lymphomas, soon started to be used to treat graft versus host disease (GvHD) developed after allogeneic hematopoietic-cell transplantation. The high response rate of ECP in skin, ocular, oral, pulmonary, and liver forms of chronic GvHD, the steroid-sparing effect, and the improved overall survival of treated patients, made ECP one of the second-line treatments used to treat steroid-resistant acute and chronic GVHD. Recently, the development of new drugs for treating GVHD has changed the position of ECP in the therapy of GVHD and has started to be used in combination with drugs for increasing the response rate to the treatment in severe or resistant forms of acute and chronic GVHD. ECP remains an essential therapeutic resource in the management of patients with refractory acute and chronic GVHD.

CS12192: A novel selective and potent JAK3 inhibitor mitigates acute graft-versus-host disease in bone marrow transplantation

BACKGROUND

Despite the significant role of JAK3 in various autoimmune diseases, including graft-versus-host disease (GVHD), there has been a lack of potent and selective JAK3 inhibitors specifically studied for GVHD. In our preclinical investigations, we evaluated a novel JAK3 inhibitor called CS12192, which is already undergoing clinical investigation in autoimmune diseases.

METHODS

We evaluated the efficacy of CS12192 in GVHD through mixed lymphocyte reaction (MLR) in both mouse and human cells, as well as allogeneic bone marrow transplantation (BMT) in a murine model.

RESULTS

CS12192, starting at a concentration of 0.5 μM, dose-dependently reduced the intracellular positivity for cytokines TNF-α and IFN-γ in CD4+ T cells (p < 0.05 to p < 0.0001) and CD8+ T cells (p < 0.01 to p < 0.0001) during mouse allogeneic MLR assays. This effect was observed for both single and double positivity of the cytokines. Moreover, In MLR assays with three different human donors, CS12192 also demonstrated a dose-dependent reduction in the proportion of IFN-γ positive CD4+ T cells (p < 0.0001) and CD8+ T cells (p < 0.01 to p < 0.0001). Additionally, it suppressed T cell proliferation in the mouse MLR (p < 0.05 to p < 0.0001), but this effect was observed in only one human donor (p < 0.001 to p < 0.0001). Furthermore, the administration of CS12192 at 40 and 80 mg/kg BID significantly improved the survival rate in the BMT model, resulting in cumulative 62-day survival rates of 88.89% (p < 0.01) and 100% (p < 0.001), respectively, compared with prednisolone (p < 0.05).

CONCLUSIONS

CS12192 is a novel, potent and selective JAK3 inhibitor demonstrating great potential to mitigate acute GVHD.

Comparing the risk of severe oral mucositis associated with methotrexate as graft-versus host-disease prophylaxis to other immunosuppressive prophylactic agents in hematopoietic cell transplantation: a systematic review and meta-analysis

PURPOSE

This study examines the risk of severe oral mucositis (SOM) in graft-versus-host disease prophylaxis (GVHD) compared to other agents in hematopoietic cell transplantation patients.

METHODS

A comprehensive search of four databases, including PubMed, Embassy, Web of Science, and Scopus, was conducted to identify studies reporting frequency and severity of oral mucositis in association with GVHD prophylactic regimens. RevMan 5.4 was used to perform the meta-analysis. Risk of bias assessment was carried out using the Rob-2 tool for randomized clinical trials (RCTs) and ROBINS-I tool for observational studies.

RESULTS

Twenty-five papers, including 11 RCTs and 14 observational studies, met the inclusion criteria. The pooled results from eight RCTs showed a higher risk of SOM in patients receiving MTX or MTX-inclusive GVHD prophylaxis versus non-MTX alternatives (RR = 1.50, 95% CI [1.20, 1.87], I2 = 36%, P = 0.0003). Mycophenolate mofetil (MMF) and post-transplant cyclophosphamide (Pt-Cy) consistently showed lower risk of mucositis than MTX. Folinic acid (FA) rescue and mini-dosing of MTX were associated with reduced oral mucositis severity.

CONCLUSION

Patients receiving MTX have a higher SOM risk compared to other approaches to prevent GVHD, which should be considered in patient care. When appropriate, MMF, FA, and a mini-dose of MTX may be an alternative that is associated with less SOM. This work also underlines the scarcity of RCTs on MTX interventions to provide the best evidence-based recommendations.

Second line extracorporeal photopheresis for cortico-resistant acute and chronic GVHD after allogeneic hematopoietic cell transplantation for hematological malignancies: Long-term results from a real-life study

BACKGROUND & OBJECTIVES

The primary objective of this observational study was to perform an exhaustive description concerning patients receiving extracorporeal photopheresis (ECP) as second line treatment after steroid resistance for either acute or chronic GVHD following allo-HCT, secondary objectives were to evaluate the efficacy and long-term outcomes.

STUDY DESIGN

A total of 106 patients were included, 65 (61%) males and 41 (39%) females with a median age at transplantation of 52 years (range: 20-67). ECP was initiated after transplantation either for acute GVHD [N = 25 (24%), 12 grade III and 13 grade IV] affecting skin alone (N = 5), gut alone (N = 12), gut and liver (N = 8), or chronic GVHD [N = 81 (76%), 15 (14%) limited and 66 (62%) extensive].

RESULTS

Among the 25 patients treated for acute GHVD, 67% were responders and among the 81 patients with chronic GVHD, 78% were responders. Patients with acute GVHD had a median OS of 6 months with a survival probability at 2 years of 35% [95%CI: 14-56]. Patients with chronic GVHD had a median OS of 72 months with a survival probability at 2 years of 68% [95%CI: 56-78]. There was a significant difference in terms of survival for patients responding to ECP compared to non-responders in both acute and chronic GVHD forms. Acute GVHD grade III-IV, negatively impacted on OS (HR=7.77, 95%CI: 1.7-34), p = 0.007 and on disease relapse HR= 5.88, 95%CI: 1.7-20, p = 0.005.

CONCLUSION

We demonstrated that ECP is an effective treatment for GVHD in a good proportion of patients with high overall response rate.

High sensitivity of host Helios+/Neuropilin-1+ Treg to pretransplant conditioning hampers development of OX40bright/integrin-β7+ regulatory cells in acute gastrointestinal GvHD

This study sought to compare the behavior of Treg subsets displaying different coexpression patterns of Neuropilin-1 (Nrp1) and Helios, under the influence of gut stress unrelated to hematopoietic stem cell transplantation, pretransplantation conditioning, and posttransplant gastrointestinal acute graft versus host disease (GI-aGvHD). Host CD4+/CD25hi/Foxp3+ Treg cells, identified by flow cytometry, were isolated from various tissues of mice affected by these stressors. Expression of CD25, CTLA-4, CD39, OX40, integrin-β7, LAG3, TGFβ/LAP, granzyme-A, -B, and interleukin-10 was compared in four Treg subsets displaying Helios or Nrp1 only, both or none. Fluorescence-activated cell sorter-sorted Treg subsets, displaying markers affected in a conditioning- and GI-aGVHD-restricted manner, were further investigated by transcriptome profiling and T-cell suppression assays. We found that conditioning by irradiation greatly diminished the relative frequency of Helios+/Nrp1+ Treg, shifting the balance toward Helios-/Nrp1- Treg in the host. Upregulation of integrin-β7 and OX40 occurred in GI-aGvHD-dependent manner in Helios+/Nrp1+ cells but not in Helios-/Nrp1- Treg. Sorted Treg subsets, confirmed to overexpress Nrp1, Helios, OX40, or integrin-β7, displayed superior immunosuppressive activity and enrichment in activation-related messenger RNA transcripts. Our data suggest that conditioning-induced shrinkage of the Nrp1+/Helios+ Treg subset may contribute to the development of GI-GvHD by impairing gut homing and decreasing the efficiency of Treg-mediated immunosuppression.

invariant Natural Killer T cell therapy as a novel therapeutic approach in hematological malignancies

Invariant Natural Killer T cell therapy is an emerging platform of immunotherapy for cancer treatment. This unique cell population is a promising candidate for cell therapy for cancer treatment because of its inherent cytotoxicity against CD1d positive cancers as well as its ability to induce host CD8 T cell cross priming. Substantial evidence supports that iNKT cells can modulate myelomonocytic populations in the tumor microenvironment to ameliorate immune dysregulation to antagonize tumor progression. iNKT cells can also protect from graft-versus-host disease (GVHD) through several mechanisms, including the expansion of regulatory T cells (Treg). Ultimately, iNKT cell-based therapy can retain antitumor activity while providing protection against GVHD simultaneously. Therefore, these biological properties render iNKT cells as a promising "off-the-shelf" therapy for diverse hematological malignancies and possible solid tumors. Further the introduction of a chimeric antigen recetor (CAR) can further target iNKT cells and enhance function. We foresee that improved vector design and other strategies such as combinatorial treatments with small molecules or immune checkpoint inhibitors could improve CAR iNKT in vivo persistence, functionality and leverage anti-tumor activity along with the abatement of iNKT cell dysfunction or exhaustion.

A Novel JAK1 Inhibitor SHR0302 Combined With Prednisone for First-Line Treatment of Chronic Graft-Versus-Host Disease: A Phase I Clinical Trial

Chronic graft-versus-host disease (cGVHD) is a potentially life-threatening complication after allogeneic hematopoietic stem cell transplantation. Standard steroid first-line treatment could not satisfy therapeutic needs due to limited efficacy. As a highly selective Janus kinase (JAK) 1 inhibitor, SHR0302 exhibits a reduced inhibition effect on JAK2 and might have less effect on hematopoiesis. This phase I clinical trial investigated the tolerability and safety of SHR0302 in combination with prednisone, and its early efficacy evidence as a potential first-line treatment to moderate/severe cGVHD. The standard 3 + 3 dose escalation was implemented to find the optimal dose of SHR0302. And prednisone was concurrently administrated with a dose of 1 mg/kg/d and then gradually tapered after 2 weeks. Eighteen patients were enrolled into the study. Grade ≥ 3 treatment-related adverse events were observed in 38.9% of patients. Only one patient developed DLT (grade ≥ 3 hypercholesterolemia) in the highest dose-level group who had pre-existing hypercholesterolemia. The maximum tolerated dose was not reached. No patient discontinued treatment due to AEs. Sixteen out of 18 patients were evaluable for responses, the ORR at week 4 and week 24 were 94.4 and 87.5%, respectively. Overall, the treatment of SHR0302 combined with prednisone was safe and well-tolerated, preliminary clinical results presented a high response for previously untreated cGVHD and a significant reduction in prednisone use in this study. A phase II trial will be conducted to further investigate its therapeutic effects clinically.

Longitudinal dynamics of gut microbiota in the pathogenesis of acute graft-versus-host disease

AIM

The gut microbiota has been reported to be associated with acute graft-versus-host disease (aGvHD) in hematopoietic stem cell transplantation (HSCT). Dynamic surveillance of the microbiota is required to understand the detailed pathogenesis involved in the process of aGvHD.

METHODS

Fecal samples were collected prospectively at four timepoints, including pre-HSCT (T1), graft infusion (T2), neutrophil engraftment (T3), and 30 days after transplantation (T4). Fecal samples were profiled by 16S ribosomal RNA gene sequencing to assess the microbiota composition.

RESULTS

From the T1 to T4 timepoint, the diversity of the gut microbiota decreased, and the dominant species also changed, with a decrease in the obligate anaerobic bacteria and a shift toward a "pathogenic community". Compared with non-aGvHD patients, aGvHD patients had a lower abundance of Roseburia at T1 and a higher abundance of Acinetobacter johnsonii at T2. Furthermore, Acinetobacter johnsonii was negatively correlated with the secretion of IL-4 and TNF-α. At T3, Rothia mucilaginos was demonstrated to be linked with a decreased risk of aGvHD, which was accompanied by decreased secretion of IL-8. At T4, higher abundances of Lactobacillus paracasei and Acinetobacter johnsonii were identified to be related with aGvHD. Lactobacillus paracasei was associated with the downregulation of IL-10, and Acinetobacter johnsonii was associated with the downregulation of IL-2 and TNF-α.

CONCLUSIONS

Dynamic changes in gut microbiota composition and related cytokines were found to be related to aGvHD, including pathogenic or protective changes. These findings suggested that manipulation of gut microbiota at different timepoints might be a promising avenue for preventing or treating this common complication.

Novel therapies for graft versus host disease with a focus on cell therapies

Graft versus host disease (GVHD) can occur at any period post allogeneic hematopoietic stem cell transplantation as a common clinical complication contributing to significant morbidity and mortality. Acute GVHD develops in approximately 30-50% of patients receiving transplants from matched related donors. High doses of steroids are used as first-line treatment, but are unsuccessful in around 40% of patients, resulting in the diagnosis of steroid-refractory acute GVHD. Consensus has yet to develop for the management of steroid-refractory acute GVHD, and prognosis at six months has been estimated at around 50%. Thus, it is critical to find effective treatments that increase survival of steroid-refractory acute GVHD. This article describes the currently known characteristics, pathophysiology, and treatments for GVHD, with a special focus on recent advances in cell therapies. In particular, a novel cell therapy using decidua stromal cells (DSCs) was recently shown to have promising results for acute GVHD, with improved effectiveness over previous treatments including mesenchymal stromal cells. At the Karolinska Institute, severe acute GVHD patients treated with placenta-derived DSCs supplemented with either 5% albumin or 10% AB plasma displayed a one-year survival rate of 76% and 47% respectively. Furthermore, patients with steroid-refractory acute GVHD, displayed survival rates of 73% with albumin and 31% with AB plasma-supplemented DSCs, compared to the 20% survival rate in the mesenchymal stromal cell control group. Adverse events and deaths were found to be attributed only to complications of hematopoietic stem cell transplant and GVHD, not to the study intervention. ASC Therapeutics, Inc, in collaboration with the Karolinska Institute, will soon initiate a phase 2 multicenter, open-label study to further assess the efficacy and safety of intravenous DSC treatment in sixty patients with Grade II-IV steroid-refractory acute GVHD. This novel cell therapy represents a promising treatment to combat the poor prognosis that steroid-refractory acute GVHD patients currently face.

Murine models of graft versus host disease (GVHD): Focus on ocular GVHD

Graft versus host disease (GVHD) remains a major and serious complication of allogeneic hematopoietic stem cell transplantation. Based on the time of onset, clinical phenotypes, progression kinetics, and pathophysiology, GVHD is stratified into acute, chronic, and overlapping types. The eyes are among the most commonly affected organs in GVHD. Mouse models have played an important role in understanding the several key elements of GVHD pathobiology. The current review discusses the immunology, pathology, and key phenotypic features of mouse models of systemic GVHD. Furthermore, a critical appraisal of mouse models of ocular GVHD (oGVHD) is provided. The disease mechanisms underlying the ocular surface, meibomian gland, and lacrimal gland injury in these models are reviewed, and the relevance of oGVHD murine models to clinical oGVHD is also included.

Galectin-3 expression in donor T cells reduces GvHD severity and lethality after allogeneic hematopoietic cell transplantation

Abundant donor cytotoxic T cells that attack normal host organs remain a major problem for patients receiving allogeneic hematopoietic cell transplantation (allo-HCT). Despite an increase in our knowledge of the pathobiology of acute graft versus host disease (aGvHD), the mechanisms regulating the proliferation and function of donor T cells remain unclear. Here, we show that activated donor T cells express galectin-3 (Gal-3) after allo-HCT. In both major and minor histocompatibility-mismatched models of murine aGvHD, expression of Gal-3 is associated with decreased T cell activation and suppression of the secretion of effector cytokines, including IFN-γ and GM-CSF. Mechanistically, Gal-3 results in activation of NFAT signaling, which can induce T cell exhaustion. Gal-3 overexpression in human T cells prevents severe disease by suppressing cytotoxic T cells in xenogeneic aGvHD models. Together, these data identify the Gal-3-dependent regulatory pathway in donor T cells as a critical component of inflammation in aGvHD.

Inflammatory CD4/CD8 double-positive human T cells arise from reactive CD8 T cells and are sufficient to mediate GVHD pathology

An important paradigm in allogeneic hematopoietic cell transplantations (allo-HCTs) is the prevention of graft-versus-host disease (GVHD) while preserving the graft-versus-leukemia (GVL) activity of donor T cells. From an observational clinical study of adult allo-HCT recipients, we identified a CD4+/CD8+ double-positive T cell (DPT) population, not present in starting grafts, whose presence was predictive of ≥ grade 2 GVHD. Using an established xenogeneic transplant model, we reveal that the DPT population develops from antigen-stimulated CD8 T cells, which become transcriptionally, metabolically, and phenotypically distinct from single-positive CD4 and CD8 T cells. Isolated DPTs were sufficient to mediate xeno-GVHD pathology when retransplanted into naïve mice but provided no survival benefit when mice were challenged with a human B-ALL cell line. Overall, this study reveals human DPTs as a T cell population directly involved with GVHD pathology.

Patterns of Renal Dysfunction and Profile of Kidney Biopsies in Hematopoietic Stem Cell Transplant Recipients

Introduction

Post hematopoietic stem cell transplant (HSCT), kidney can be subjected to injury by various causes. Of these, graft versus host disease (GvHD) affecting the kidney is an under-recognized entity with no clear guidelines on its diagnosis, clinicopathological manifestations, and outcomes.

Material and Methods

Out of 2,930 patients who underwent HSCT at our center between 2005 and 2020, kidney biopsy was performed in 19 allogenic and 5 autologous recipients.

Results

The mean age of the cohort at transplant was 33.2 ± 7 years, and 15 (62%) were males. Median time to kidney biopsy from HSCT was 14 (IQR, 9-30) months. Aplastic anemia was the most common underlying hematological disease (54.2%). All 19 allogenic recipients were classified based on clinicopathological manifestations into either thrombotic microangiopathy (TMA, 12/19 [63%]) or nephrotic syndrome (NS, 7/19 [37%]) pattern. Glomerular tuft "mesangiolysis" was the dominant pattern of injury noted in 9/12 cases of TMA pattern. There was a predominance of acute microangiopathic changes restricted primarily to the glomerular compartment. Of the 7 patients with NS pattern, membranous nephropathy was seen in 4 (57%) and minimal change disease in 3 (43%) patients. Thirty-nine percent (7/18) stained positive for C4d which was predominantly glomerular. Allogenic recipients who did not receive immunosuppression (IS) for renal disease had a lower eGFR at biopsy, a longer latency between withdrawal of GvHD prophylaxis and biopsy, and were significantly at a higher risk of kidney failure (IS: 2/11, 18.1% vs. no IS: 2/6, 33.3%, p = 0.04). "Associated extra-renal GvHD" occurred in 11/19 (57.9%) allogenic recipients. Patients with "associated extra-renal GvHD" had significantly more deaths (6/11, 60% vs. 0, p = 0.02) but comparable renal outcomes.

Conclusion

Renal GvHD can present with or without "associated extra-renal GvHD" after a prolonged period of withdrawal of GvHD prophylaxis, requiring careful diagnostic vigilance and consideration of IS.

Milestones in acute GVHD pathophysiology

In the past 65 years, over 25 000 referenced articles have been published on graft-versus-host disease (GVHD). Although this included clinically orientated papers or publications on chronic GVHD, the conservative estimate of scientific publications still contains several thousands of documents on the pathophysiology of acute GVHD. Thus, summarizing what we believe are prominent publications that can be considered milestones in our knowledge of this disease is a challenging and inherently biased task. Here we review from a historical perspective what can be regarded as publications that have made the field move forward. We also included several references of reviews on aspects we could not cover in detail.

Established and Emerging Treatments of Skin GvHD

Graft-versus-host disease (GvHD) of the skin is a severe allo-immune reaction and complication following allogeneic stem cell transplantation. Over the past years, intensive pre-clinical research has led to an improved understanding of the pathophysiology of acute and to a lesser extend chronic GvHD. This has translated into the approval of several new agents for the treatment of both forms of GvHD. This review summarizes the most recent advances in underlying pathomechanisms, clinical trials and newly approved agents for GvHD, with a special focus on skin involvement.

Management of Chronic Graft-vs.-Host Disease in Children and Adolescents With ALL: Present Status and Model for a Personalised Management Plan

Herein we review current practice regarding the management of chronic graft-vs.-host disease (cGvHD) in paediatric patients after allogeneic haematopoietic stem cell transplantation (HSCT) for acute lymphoblastic leukaemia (ALL). Topics covered include: (i) the epidemiology of cGvHD; (ii) an overview of advances in our understanding cGvHD pathogenesis; (iii) current knowledge regarding risk factors for cGvHD and prevention strategies complemented by biomarkers; (iii) the paediatric aspects of the 2014 National Institutes for Health-defined diagnosis and grading of cGvHD; and (iv) current options for cGvHD treatment. We cover topical therapy and newly approved tyrosine kinase inhibitors, emphasising the use of immunomodulatory approaches in the context of the delicate counterbalance between immunosuppression and immune reconstitution as well as risks of relapse and infectious complications. We examine real-world approaches of response assessment and tapering schedules of treatment. Furthermore, we report on the optimal timepoints for therapeutic interventions and changes in relation to immune reconstitution and risk of relapse/infection. Additionally, we review the different options for anti-infectious prophylaxis. Finally, we put forth a theory of a holistic view of paediatric cGvHD and its associated manifestations and propose a checklist for individualised risk evaluation with aggregated considerations including site-specific cGvHD evaluation with attention to each individual's GvHD history, previous medical history, comorbidities, and personal tolerance and psychosocial circumstances. To complement this checklist, we present a treatment algorithm using representative patients to inform the personalised management plans for patients with cGvHD after HSCT for ALL who are at high risk of relapse.