Pharmacologic blockade of JAK1/JAK2 reduces GvHD and preserves the graft-versus-leukemia effect

The application of JAK inhibitors in the peri-transplantation period of hematopoietic stem cell transplantation for myelofibrosis

Myelofibrosis (MF) is a myeloproliferative neoplasm (MPN) with a poor prognosis, and allogeneic hematopoietic stem cell transplantation (allo-HSCT) is the only treatment with curative potential. Ruxolitinib, a JAK1/2 inhibitor, has shown promising results in improving patients' symptoms, overall survival, and quality of life, and can be used as a bridging therapy to HSCT that increases the proportion of transplantable patients. However, the effect of this and similar drugs on HSCT outcomes is unknown, and the reports on their efficacy and safety in the peri-transplantation period vary widely in the published literature. This paper reviews clinical data related to the use of JAK inhibitors in the peri-implantation phase of hematopoietic stem cell transplantation for primary myelofibrosis and discusses their efficacy and safety.

New investigational drugs for steroid-refractory acute graft-versus-host disease: a review of the literature

INTRODUCTION

Steroid-refractory acute graft-versus-host disease (SR-aGVHD) remains a formidable obstacle in the field of allogeneic hematopoietic cell transplantation (allo-HCT), significantly contributing to patient morbidity and mortality. The current therapeutic landscape for SR-aGVHD is limited, often yielding suboptimal results, thereby emphasizing the urgent need for innovative and effective treatments.

AREAS COVERED

In light of the pivotal REACH2 trial, ruxolitinib phosphate, a Janus kinase inhibitor, has gained prominence as the standard treatment for SR-aGVHD. Nevertheless, a considerable number of patients either do not respond to or cannot tolerate this therapy. This review delves into emerging treatments for SR-aGVHD, including mesenchymal stromal cells (MSCs), fecal microbiota transplantation (FMT), CD3/CD7 blockade, neihulizumab, begelomab, tocilizumab, and vedolizumab. While some of these agents have shown encouraging results in early-phase trials, issues such as treatment-related toxicities and inconsistent responses in larger studies highlight the necessity for ongoing research.

EXPERT OPINION

Current trials exploring new agents and combination therapies offer hope for fulfilling the unmet clinical needs in SR-aGVHD, potentially leading to more effective and precise treatment strategies.

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.

The impact of regulatory T cells on the graft-versus-leukemia effect

Allogeneic Hematopoietic Stem Cell Transplantation (allo-HSCT) is the only curative therapy for many hematologic malignancies, whereby the Graft-versus-Leukemia (GVL) effect plays a pivotal role in controlling relapse. However, the success of GVL is hindered by Graft-versus-Host Disease (GVHD), where donor T cells attack healthy tissues in the recipient. The ability of natural regulatory T cells (Treg) to suppress immune responses has been exploited as a therapeutical option against GVHD. Still, it is crucial to evaluate if the ability of Treg to suppress GVHD does not compromise the benefits of GVL. Initial studies in animal models suggest that Treg can attenuate GVHD while preserving GVL, but results vary according to tumor type. Human trials using Treg as GVHD prophylaxis or treatment show promising results, emphasizing the importance of infusion timing and Treg/Tcon ratios. In this review, we discuss strategies that can be used aiming to enhance GVL post-Treg infusion and the proposed mechanisms for the maintenance of the GVL effect upon the adoptive Treg transfer. In order to optimize the therapeutic outcomes of Treg administration in allo-HSCT, future efforts should focus on refining Treg sources for infusion and evaluating their specificity for antigens mediating GVHD while preserving GVL responses.

Novel JAK Inhibitors to Reduce Graft-Versus-Host Disease after Allogeneic Hematopoietic Cell Transplantation in a Preclinical Mouse Model

Allogeneic hematopoietic cell transplantation (allo-HCT) is a highly effective, well-established treatment for patients with various hematologic malignancies and non-malignant diseases. The therapeutic benefits of allo-HCT are mediated by alloreactive T cells in donor grafts. However, there is a significant risk of graft-versus-host disease (GvHD), in which the donor T cells recognize recipient cells as foreign and attack healthy organs in addition to malignancies. We previously demonstrated that targeting JAK1/JAK2, mediators of interferon-gamma receptor (IFNGR) and IL-6 receptor signaling, in donor T cells using baricitinib and ruxolitinib results in a significant reduction in GvHD after allo-HCT. Furthermore, we showed that balanced inhibition of JAK1/JAK2 while sparing JAK3 is important for the optimal prevention of GvHD. Thus, we have generated novel JAK1/JAK2 inhibitors, termed WU derivatives, by modifying baricitinib. Our results show that WU derivatives have the potential to mitigate GvHD by upregulating regulatory T cells and immune reconstitution while reducing the frequencies of antigen-presenting cells (APCs) and CD80 expression on these APCs in our preclinical mouse model of allo-HCT. In addition, WU derivatives effectively downregulated CXCR3 and T-bet in primary murine T cells. In summary, we have generated novel JAK inhibitors that could serve as alternatives to baricitinib or ruxolitinib.

Using Targeted Transcriptome and Machine Learning of Pre- and Post-Transplant Bone Marrow Samples to Predict Acute Graft-versus-Host Disease and Overall Survival after Allogeneic Stem Cell Transplantation

Acute graft-versus-host disease (aGvHD) remains a major cause of morbidity and mortality after allogeneic hematopoietic stem cell transplantation (HSCT). We performed RNA analysis of 1408 candidate genes in bone marrow samples obtained from 167 patients undergoing HSCT. RNA expression data were used in a machine learning algorithm to predict the presence or absence of aGvHD using either random forest or extreme gradient boosting algorithms. Patients were randomly divided into training (2/3 of patients) and validation (1/3 of patients) sets. Using post-HSCT RNA data, the machine learning algorithm selected 92 genes for predicting aGvHD that appear to play a role in PI3/AKT, MAPK, and FOXO signaling, as well as microRNA. The algorithm selected 20 genes for predicting survival included genes involved in MAPK and chemokine signaling. Using pre-HSCT RNA data, the machine learning algorithm selected 400 genes and 700 genes predicting aGvHD and overall survival, but candidate signaling pathways could not be specified in this analysis. These data show that NGS analyses of RNA expression using machine learning algorithms may be useful biomarkers of aGvHD and overall survival for patients undergoing HSCT, allowing for the identification of major signaling pathways associated with HSCT outcomes and helping to dissect the complex steps involved in the development of aGvHD. The analysis of pre-HSCT bone marrow samples may lead to pre-HSCT interventions including choice of remission induction regimens and modifications in patient health before HSCT.

CRISPR/Cas9 deletion of MIR155HG in human T cells reduces incidence and severity of acute GVHD in a xenogeneic model

ABSTRACT

Acute graft-versus-host disease (GVHD) is a major complication of allogeneic hematopoietic cell transplantation (allo-HCT). Using preclinical mouse models of disease, previous work in our laboratory has linked microRNA-155 (miR-155) to the development of acute GVHD. Transplantation of donor T cells from miR-155 host gene (MIR155HG) knockout mice prevented acute GVHD in multiple murine models of disease while maintaining critical graft-versus-leukemia (GVL) response, necessary for relapse prevention. In this study, we used clustered, regularly interspaced, short palindromic repeats (CRISPR)/Cas9 genome editing to delete miR-155 in primary T cells (MIR155HGΔexon3) from human donors, resulting in stable and sustained reduction in expression of miR-155. Using the xenogeneic model of acute GVHD, we show that NOD/SCID/IL2rγnull (NSG) mice receiving MIR155HGΔexon3 human T cells provide protection from lethal acute GVHD compared with mice that received human T cells with intact miR-155. MIR155HGΔexon3 human T cells persist in the recipients displaying decreased proliferation potential, reduced pathogenic T helper-1 cell population, and infiltration into GVHD target organs, such as the liver and skin. Importantly, MIR155HGΔexon3 human T cells retain GVL response significantly improving survival in an in vivo model of xeno-GVL. Altogether, we show that CRISPR/Cas9-mediated deletion of MIR155HG in primary human donor T cells is an innovative approach to generate allogeneic donor T cells that provide protection from lethal GVHD while maintaining robust antileukemic response.

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.

ROCK1/2 signaling contributes to corticosteroid-refractory acute graft-versus-host disease

Patients with corticosteroid-refractory acute graft-versus-host disease (aGVHD) have a low one-year survival rate. Identification and validation of novel targetable kinases in patients who experience corticosteroid-refractory-aGVHD may help improve outcomes. Kinase-specific proteomics of leukocytes from patients with corticosteroid-refractory-GVHD identified rho kinase type 1 (ROCK1) as the most significantly upregulated kinase. ROCK1/2 inhibition improved survival and histological GVHD severity in mice and was synergistic with JAK1/2 inhibition, without compromising graft-versus-leukemia-effects. ROCK1/2-inhibition in macrophages or dendritic cells prior to transfer reduced GVHD severity. Mechanistically, ROCK1/2 inhibition or ROCK1 knockdown interfered with CD80, CD86, MHC-II expression and IL-6, IL-1β, iNOS and TNF production in myeloid cells. This was accompanied by impaired T cell activation by dendritic cells and inhibition of cytoskeletal rearrangements, thereby reducing macrophage and DC migration. NF-κB signaling was reduced in myeloid cells following ROCK1/2 inhibition. In conclusion, ROCK1/2 inhibition interferes with immune activation at multiple levels and reduces acute GVHD while maintaining GVL-effects, including in corticosteroid-refractory settings.

Planning GvHD preemptive therapy: risk factors, biomarkers, and prognostic scores

Prevention of acute and chronic graft-versus-host disease (aGvHD and cGvHD) is an important objective of allogeneic hematopoietic cell transplantation (HCT). While there is has been significant progress in preventative approaches in the peritransplant period to minimize development of GvHD, no preventative approach has completely eliminated development of either aGvHD or cGvHD. Recently, posttransplant immune biomarker profiling early post-HCT by the Mount Sinai Acute GvHD International Consortium group has resulted in a validated risk assignment algorithm and development of preemptive approaches to decrease aGvHD and mortality in high-risk patients. cGvHD risk assignment algorithms have been developed based on measurements at day 100 and may be used for future preemptive intervention trials to minimize cGvHD. This article discusses the current state of the art in aGvHD and cGvHD preemptive algorithms and therapeutic interventions and what is needed to move these into validated approaches.

Ruxolitinib versus basiliximab for steroid-refractory acute graft-versus-host disease: a retrospective study

Acute graft-versus-host disease (aGVHD) remains a major limitation of allogeneic hematopoietic stem cell transplantation; not all patients respond to standard glucocorticoids treatment. This study retrospectively evaluated the effects of ruxolitinib compared with basiliximab for steroid-refractory aGVHD (SR-aGVHD). One hundred and twenty-nine patients were enrolled, 81 in ruxolitinib and 48 in basiliximab group. The overall response (OR) at day 28 was higher in ruxolitinib group (72.8% vs. 54.2%, P = 0.031), as with complete response (CR) (58.0% vs. 35.4%, P = 0.013). Ruxolitinib led to significantly lower 1-year cumulative incidence of chronic GVHD (cGVHD) (29.6% vs. 43.8%, P = 0.021). Besides, ruxolitinib showed higher 1-year overall survival (OS) and 1-year cumulative incidence of failure-free survival (FFS) (OS: 72.8% vs. 50.0%, P = 0.008; FFS: 58.9% vs. 39.6%, P = 0.014). The 1-year cumulative incidence of non-relapse mortality (NRM) was lower in ruxolitinib group (16.1% vs. 37.5%, P = 0.005), and the 1-year relapse was not different. The 1-year cumulative incidence of cytomegalovirus (CMV) viremia, CMV-associated diseases and Epstein-Barr virus (EBV)-associated diseases was similar between the two groups, but EBV viremia was significantly lower in ruxolitinib group (6.2% vs. 29.2%, P < 0.001). Subgroup analyses revealed that OR and survival were similar in ruxolitinib 5 mg twice daily (bid) and 10 mg bid groups. However, ruxolitinib 10 mg bid treatment markedly reduced 1-year cumulative incidence of cGVHD compared with 5 mg bid (21.1% vs. 50.0%, P = 0.016). Our study demonstrated that ruxolitinib was superior to basiliximab in SR-aGVHD treatment and cGVHD prophylaxis, therefore should be recommended.

Amyloidogenic propensity of self-assembling peptides and their adjuvant potential for use as DNA vaccines

De novo designed peptides that self-assemble into cross-β rich fibrillar biomaterials have been pursued as an innovative platform for the development of adjuvant- and inflammation-free vaccines. However, they share structural and morphological properties similar to amyloid species implicated in neurodegenerative diseases, which has been a long-standing concern for their successful translation. Here, we comprehensively characterize the amyloidogenic character of the amphipathic self-assembling cross-β peptide KFE8, compared to pathological amyloid and amyloid-like proteins α-synuclein (α-syn) and TDP-43. Further, we developed plasmid-based DNA vaccines with the KFE8 backbone serving as a scaffold for delivery of a GFP model antigen. We find that expression of tandem repeats of KFE8 is non-toxic and efficiently cleared by autophagy. We also demonstrate that preformed KFE8 fibrils do not cross-seed amyloid formation of α-syn in mammalian cells compared to α-syn preformed fibrils. In mice, vaccination with plasmids encoding the KFE32-GFP fusion protein elicited robust immune responses, inducing production of significantly higher levels of anti-GFP antibodies compared to soluble GFP. Antigen-specific CD8+T cells were also detected in the spleens of vaccinated mice and cytokine profiles from antigen recall assays indicate a balanced Th1/Th2 response. These findings illustrate that cross-β-rich peptide nanofibers have distinct physicochemical properties from those of pathological amyloidogenic proteins, and are an attractive platform for the development of DNA vaccines with self-adjuvanting properties and improved safety profiles. STATEMENT OF SIGNIFICANCE: Biomaterials comprised of self-assembling peptides hold great promise for the development of new vaccines that do not require use of adjuvants. However, these materials have safety concerns, as they self-assemble into cross-β rich fibrils that are structurally similar to amyloid species implicated in disease. Here, we comprehensively study the properties of these biomaterials. We demonstrate that they have distinct properties from pathological proteins. They are non-toxic and do not trigger amyloidogenesis. Vaccination of these materials in mice elicited a robust immune response. Most excitingly, our work suggests that this platform could be used to develop DNA-based vaccines, which have few storage requirements. Further, due to their genetic encoding, longer sequences can be generated and the vaccines will be amenable to modification.

Treatment of steroid-refractory graft versus host disease in children

Systemic steroids are still the first-line approach in acute graft-versus-host disease (aGvHD), and the backbone of chronic GvHD management. Refractoriness to steroid represent a major cause of morbidity and non-relapse mortality after hematopoietic stem cell transplantation (HSCT). In both backgrounds, several second-line immunosuppressive agents have been tested with variable results in terms of efficacy and toxicity. Solid evidence regarding these approaches is still lacking in the pediatric setting where results are mainly derived from adult experiences. Furthermore, the number of treated patients is limited and the incidence of acute and chronic GvHD is lower, resulting in a very heterogeneous approach to this complication by pediatric hematologists. Some conventional therapies and anti-cytokine monoclonal antibodies used in the adult setting have been evaluated in children. In recent years, the increasing understanding of the biological mechanisms underpinning the pathogenesis of GvHD justified the efforts toward the adoption of targeted therapies and non-pharmacologic approaches, with higher response rates and lower immunosuppressive effects. Moreover, many questions regarding the precise timing and setting in which to integrate these new approaches remain unanswered. This Review aims to critically explore the current evidence regarding novel approaches to treat SR-GvHD in pediatric HSCT recipients.

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.

Ruxolitinib as the first post-steroid treatment for acute and chronic graft-versus-host disease

INTRODUCTION

Acute and chronic graft-versus-host disease (GvHD) are potentially life-threatening complications occurring after allogeneic stem cell transplantation (allo-HSCT). Although steroids represent the first-line treatment for both conditions, in those patients who do not adequately benefit from steroid therapy, standardized treatment algorithms are lacking. In recent years, ruxolitinib has emerged as the most promising agent for the second-line therapy of steroid-refractory (SR)-GvHD.

AREAS COVERED

This review will summarize the biological properties and the mechanistic aspects that justify the therapeutic role of ruxolitinib in GvHD. In addition, current treatment options for SR-GvHD will be briefly discussed. Finally, results of the most relevant clinical trials on the use of ruxolitinib for SR-GvHD will be analyzed, with a particular focus on two phase-III randomized trials in which ruxolitinib demonstrated its superiority in comparison with the best available therapy.

EXPERT OPINION

Ruxolitinib has considerably improved the outcome of patients with SR-acute/chronic-GvHD and should be regarded as the standard-of-care option when corticosteroids fail or cannot be tapered. Nevertheless, a number of questions still remain unanswered and significant room for improvement exists. Additional observations derived from a longer follow-up will certainly increase our expertise in the management of this powerful therapy.

Acute Graft-versus-Host Disease: An Update on New Treatment Options

Acute graft-versus-host disease (GVHD) occurs in approximately 50% of patients and remains a primary driver of non-relapse and transplant-related mortality. The best treatment remains prevention with either in vivo or ex vivo T-cell depletion, with multiple strategies used worldwide based on factors such as institution preference, ability to perform graft manipulation, and ongoing clinical trials. Predicting patients at high risk for developing severe acute GVHD based on clinical and biomarker-based criteria allows for escalation or potential de-escalation of therapy. Modern therapies for treatment of the disease include JAK/STAT pathway inhibitors, which are standard of care in the second-line setting and are being investigated for upfront management of non-severe risk based on biomarkers. Salvage therapies beyond the second-line remain suboptimal. In this review, we will focus on the most clinically used GVHD prevention and treatment strategies, including the accumulating data on JAK inhibitors in both settings.

A Multicenter Phase 2 Clinical Trial of 10-Day Decitabine, Dose-Escalated Donor Lymphocyte Infusion, and Ruxolitinib for Relapsed Acute Myeloid Leukemia and Myelodysplastic Syndromes after Allogeneic Hematopoietic Cell Transplantation

Post-transplantation relapse of acute myeloid leukemia and myelodysplastic syndromes has a poor prognosis. Donor lymphocyte infusion (DLI) is one treatment approach. However, efficacy is limited, and toxicity, mostly in the form of acute graft-versus-host disease (GVHD), is frequent. We tested a novel approach using 10-day decitabine, dose-escalated DLI, and ruxolitinib in a multicenter phase 2 trial aimed at increasing the efficacy of DLI and reducing its toxicity. Up to four 28-day cycles were administered. The primary endpoint was 6-month overall survival (OS). Of the 14 patients who started cycle 1, 13 received 1 DLI, 6 received 2 DLIs, and 1 received 3 4 DLIs. A preplanned interim analysis after enrolling 14 patients suggested futility, and the trial was closed to accrual. The final analysis showed a 6-month OS of 36% (95% confidence interval [CI], 18 to 72), a 1-year progression-free survival of 7% (95% CI, 1% to 47%), a 6-month cumulative incidence of grade II-IV acute GVHD of 57% (95% CI, 26% to 80%), and a 1-year nonrelapse mortality of 14% (95% CI, 2% to 38%). The combined modality treatment studied in this trial was ineffective and did not reduce DLI toxicity.

Addition of ruxolitinib in Graft-versus-Host disease prophylaxis for pediatric β-Thalassemia major patients after allogeneic stem cell transplantation: A retrospective cohort study

BACKGROUND

To evaluate the effect of addition of ruxolitinib in Graft-versus-Host Disease (GVHD) prophylaxis on pediatric patients with β-thalassemia major after allogeneic hematopoietic stem cell transplantation(HSCT).

METHODS

This retrospective study reviewed 49 consecutive β-thalassemia major pediatric patients who underwent HSCT from unrelated or haploidentical donors from February 2018 to October 2022. All transplantation recipients received cyclosporine A (CsA), mycophenolate mofetil (MMF), and short-term methotrexate (MTX) as GVHD prophylaxis; while 27 of them in the ruxolitinib group had added ruxolitinib oral to GVHD prophylaxis regimen at 2.5 mg twice daily once successful engraftment after January 2020.

RESULTS

The outcome showed that the ruxolitinib group had a lower cumulative incidence than the control group regardless of acute GVHD (22.2% vs.40.9%; p = .153) or chronic GVHD (18.5% vs.40.9%; p = .072); especially, the incidence of grade III-IV acute GVHD was reported significantly less frequently in ruxolitinib group than that of the control group (0 vs. 27.3%, p = .005). No significant difference was detected between the two groups in EBV (Epstein-Barr virus)/CMV (cytomegalovirus) reactivation and BKV (BK virus) infection (p = .703, 1.000, and .436, respectively). Twenty-six patients (96.3%) in the ruxolitinib group were alive, while two patients (9.1%) in the control group died of intestinal acute GVHD. The 2-year overall survival (OS) and thalassemia-free survival (TFS) were both 96.296% in the ruxolitinib group, while both 90.909% in the control group.

CONCLUSION

This study reveals that ruxolitinib prophylaxis is a promising option to decrease the incidence of grade III-IV acute GVHD in pediatric patients with β-thalassemia major.

S100A9 upregulated by IFNGR signaling blockade functions as a novel GVHD suppressor without compromising GVL in mice

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a curative treatment for both malignant and nonmalignant hematologic disorders. However, graft-versus-host disease (GVHD) and malignant relapse limit its therapeutic success. We previously demonstrated that the blockade of interferon-gamma receptor (IFNGR) signaling in donor T cells resulted in a reduction in GVHD while preserving graft-versus-leukemia (GVL) effects. However, the underlying molecular mechanisms remain inconclusive. In this study, we found that S100A9 is a novel GVHD suppressor upregulated when IFNGR is blocked in T cells. Both Ifngr1-/- and S100a9-overexpressing T cells significantly reduced GVHD without compromising GVL, altering donor T-cell trafficking to GVHD target organs in our mouse model of allo-HSCT. In addition, in vivo administration of recombinant murine S100A9 proteins prolongs the overall survival of recipient mice. Furthermore, in vivo administration of anti-human IFNGRα neutralizing antibody (αhGR-Nab) significantly upregulates the expression of S100A9 in human T cells and improved GVHD in our mouse model of xenogeneic human peripheral blood mononuclear cell transplantation. Consistent with S100a9-overexpressing T cells in our allo-HSCT model, αhGR-Nab reduced human T-cell trafficking to the GVHD target organs. Taken together, S100A9, a downstream molecule suppressed by IFNGR signaling, functions as a novel GVHD suppressor without compromising GVL.

Effective treatment of low-risk acute GVHD with itacitinib monotherapy

The standard primary treatment for acute graft-versus-host disease (GVHD) requires prolonged, high-dose systemic corticosteroids (SCSs) that delay reconstitution of the immune system. We used validated clinical and biomarker staging criteria to identify a group of patients with low-risk (LR) GVHD that is very likely to respond to SCS. We hypothesized that itacitinib, a selective JAK1 inhibitor, would effectively treat LR GVHD without SCS. We treated 70 patients with LR GVHD in a multicenter, phase 2 trial (NCT03846479) with 28 days of itacitinib 200 mg/d (responders could receive a second 28-day cycle), and we compared their outcomes to those of 140 contemporaneous, matched control patients treated with SCSs. More patients responded to itacitinib within 7 days (81% vs 66%, P = .02), and response rates at day 28 were very high for both groups (89% vs 86%, P = .67), with few symptomatic flares (11% vs 12%, P = .88). Fewer itacitinib-treated patients developed a serious infection within 90 days (27% vs 42%, P = .04) due to fewer viral and fungal infections. Grade ≥3 cytopenias were similar between groups except for less severe leukopenia with itacitinib (16% vs 31%, P = .02). No other grade ≥3 adverse events occurred in >10% of itacitinib-treated patients. There were no significant differences between groups at 1 year for nonrelapse mortality (4% vs 11%, P = .21), relapse (18% vs 21%, P = .64), chronic GVHD (28% vs 33%, P = .33), or survival (88% vs 80%, P = .11). Itacitinib monotherapy seems to be a safe and effective alternative to SCS treatment for LR GVHD and deserves further investigation.

Real-world experience with ruxolitinib for steroid-refractory acute graft-versus-host disease: a single center experience

Steroid-refractory acute graft-versus-host disease (SR-aGVHD) remains a major cause of morbidity and mortality after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Ruxolitinib (RUX), an oral JAK1 and JAK2 inhibitor, has recently been approved for patients with SR-aGVHD. The aim of this study was to evaluate RUX efficacy and toxicity in a real-world setting. Eighteen patients received RUX at 5 mg or 10 mg twice a day after a median 3 lines of prior unsuccessful immunosuppressive therapy. Median time on RUX therapy was 28 days (range 7-129). Five patients (28%) responded to RUX, including 4 complete responses and 1 partial response. Response to RUX was irrespective of aGVHD grade and the number of involved organs. One-year overall survival (OS) was 60% for RUX-responders versus 31% for non-responders (p = ns). Treatment duration greater than 29.5 days was found to have a positive impact on OS (p < 0.007). Major adverse events during RUX treatment were grade 3-4 thrombocytopenia (61% of patients) and cytomegalovirus reactivation (50%). After median follow-up of 55 days (range 29-706), 14 patients (78%) died, mainly due to further progression of GVHD. RUX may represent a valuable therapeutic option for some patients with advanced SR-aGVHD, but more studies are warranted.

Efficacy and safety of ruxolitinib for steroid-refractory graft-versus-host disease: Systematic review and meta-analysis of randomised and non-randomised studies

Background

Hematopoietic stem cell transplantation (HSCT) for haematological disorders. Graft-versus-host disease (GVHD), a cause of morbidity and mortality is treated with corticosteroids. However, patients with steroid-refractory GVHD after HSCT have a poor prognosis. Ruxolitinib, a selective Janus kinase inhibitor, is a novel treatment strategy for steroid-refractory GVHD.

Objectives

To assess the efficacy of ruxolitinib for the treatment of steroid-refractory GVHD and analyse its adverse effects.

Study design

Meta-analysis.

Search methods

Randomised controlled trials (RCTs) and non-RCTs of ruxolitinib-based therapy in patients with steroid-refractory GVHD were found in the Cochrane Central Register of Controlled Trials, EMBASE, PubMed, and Web of Science in March 2021. Outcomes included overall response rate, survival, and adverse effects. The Methodological Index for Non-randomised Studies (MINORS) and the Cochrane collaboration risk-of-bias tool were used to assess methodological quality. Funnel plots, Egger’s test, and the trim and fill method were used to assess publication bias.

Results

In total, 1470 studies were identified; 19 studies (17 non-RCTs, 2 RCTs) involving 1358 patients met our inclusion criteria. Survival rates at the longest follow-up in non-RCTs, were 57.5% (95% CI 46.9–67.4) and 80.3% (95% CI 69.7–87.9) for acute GVHD (aGVHD) and chronic GVHD (cGVHD), respectively. In non-RCTs, the overall response was 74.9% (95% CI 66.6–81.8, I² = 49%) in aGVHD and 73.1% (95% CI 62.5–81.6, I² = 49%) in cGVHD. In aGVHD, the response rates were gastrointestinal, 61.4–90.2%; skin, 52.5–80.6%; and liver, 41.8–71.8%. In cGVHD, the response rates were gastrointestinal, 30.1–70.4%; skin, 30.1–84.4%; lung, 27.0–83.0%; and mouth 3.5–98.1%. In addition, a lower aGVHD grade and moderate cGVHD were associated with a better clinical response. Common adverse events were cytopenia and infectious complications.

Conclusions

Our systematic review and meta-analysis indicated that ruxolitinib therapy could be a potentially effective and safe treatment for patients with steroid-refractory GVHD.

Fedratinib, the first selective JAK2 inhibitor approved for treatment of myelofibrosis - an option beyond ruxolitinib

Introduction: Myelofibrosis, a life shortening clonal disorder, presents with a constellation of features: bone marrow fibrosis, abnormal blood counts, extramedullary hematopoiesis, splenomegaly, thrombohemorrhagic complications and constitutional symptoms. Until recently Ruxolitinib, a JAK1 and 2 inhibitor, has been the only targeted therapy available for transplant-ineligible patients requiring treatment for splenomegaly and disease related symptoms. However, most patients discontinue Ruxolitinib after 3-5 years, mostly due to loss of response. There has been an unmet need for this patient group. In August 2019 Fedratinib (INREBIC® capsules, Impact Biomedicines, Inc., a wholly owned subsidiary of Bristol Meyer Squibb), a JAK2 inhibitor, was approved by US FDA for treatment of myelofibrosis in both JAK inhibitor naïve and pre-treated patients for the management of symptoms and splenomegaly.Areas covered: Here, we discuss the development, evidence base to date for Fedratinib. Including early and late phase, and ongoing trials, safety issues, potential role and current position of Fedratinib in the treatment of myelofibrosis, as well as future direction of targeted therapy in myelofibrosis.Expert opinion: Fedratinib presents a much needed option of treatment, particularly, for patients failing Ruxolitinib, with response rates that are quite similar. Nonetheless, there remain important questions including sequencing and options for combining therapy.

JAK2 gene knockout inhibits corneal allograft rejection in mice by regulating dendritic cell-induced T cell immune tolerance

Corneal allograft rejection can be seen in some patients after corneal transplantation. The present study intends to investigate whether JAK2 gene knockout affects corneal allograft rejection through regulation of dendritic cells (DCs)-induced T cell immune tolerance. In order to identify the target gene related to corneal allograft rejection, high-throughput mRNA sequencing and bioinformatics analysis were performed. JAK2 knockout mice were constructed and subjected to corneal allograft transplantation. The incidence of immune rejection was observed, the percentage of CD4⁺ T cells was detected, and the expression of Th1 cytokine interferon γ (IFN-γ) was determined. Flow cytometry and ELISA were performed to analyze the effects of JAK2 gene knockout on bone marrow-derived DCs (BMDCs). JAK2 was the target gene related to corneal allograft rejection. JAK2 gene knockout contributed to significantly prolonged survival time of corneal grafts in mice and inhibited corneal allograft rejection. The in vitro cell experiment further confirmed that JAK2 gene knockout contributed to the inactivation of CD4⁺ T cells and induced IFN-γ expression, accompanied by inhibition of DC immune function, development, maturation, and secretion of inflammatory cytokines. Collectively, JAK2 gene knockout inactivates CD4⁺ T cells to decrease IFN-γ expression, as well as inhibits DC development, maturation, and secretion of inflammatory cytokines, thereby reducing corneal allograft rejection.

The role of JAK inhibitors in hematopoietic cell transplantation

The Janus Kinase (JAK)/Signal Transducers and Activators of Transcription (STAT) pathway is essential for both the regulation of hematopoiesis and the control of inflammation. Disruption of this pathway can lead to inflammatory and malignant disease processes. JAK inhibitors, designed to control the downstream effects of pro-inflammatory and pro-angiogenic cytokines, have been successfully used in pre-clinical models and clinical studies of patients with autoimmune diseases, hematologic malignancies, and the hematopoietic cell transplantation (HCT) complication graft versus host disease (GVHD). In the last decade, JAK inhibitors Ruxolitinib, Fedratinib, and most recently Pacritinib have been United States Federal Drug Administration (FDA) approved for the treatment of myelofibrosis (MF). Ruxolitinib was also recently approved for the treatment of steroid refractory acute as well as chronic GVHD; JAK inhibitors are currently under evaluation in the pre-HCT setting in MF and for the prevention of GVHD. This review will focus on the role of JAK inhibitors in the treatment of hematologic malignancies, the potential function of pre-HCT JAK inhibitors in patients with MF, and the role of JAK inhibitors in the prevention and treatment of acute and chronic GVHD.

Dual JAK2/Aurora kinase A inhibition prevents human skin graft rejection by allo-inactivation and ILC2-mediated tissue repair

Prevention of allograft rejection often requires lifelong immune suppression, risking broad impairment of host immunity. Nonselective inhibition of host T cell function increases recipient risk of opportunistic infections and secondary malignancies. Here we demonstrate that AJI-100, a dual inhibitor of JAK2 and Aurora kinase A, ameliorates skin graft rejection by human T cells and provides durable allo-inactivation. AJI-100 significantly reduces the frequency of skin-homing CLA⁺ donor T cells, limiting allograft invasion and tissue destruction by T effectors. AJI-100 also suppresses pathogenic Th1 and Th17 cells in the spleen yet spares beneficial regulatory T cells. We show dual JAK2/Aurora kinase A blockade enhances human type 2 innate lymphoid cell (ILC2) responses, which are capable of tissue repair. ILC2 differentiation mediated by GATA3 requires STAT5 phosphorylation (pSTAT5) but is opposed by STAT3. Further, we demonstrate that Aurora kinase A activation correlates with low pSTAT5 in ILC2s. Importantly, AJI-100 maintains pSTAT5 levels in ILC2s by blocking Aurora kinase A and reduces interference by STAT3. Therefore, combined JAK2/Aurora kinase A inhibition is an innovative strategy to merge immune suppression with tissue repair after transplantation.

T Helper Cell Lineage-Defining Transcription Factors: Potent Targets for Specific GVHD Therapy?

Allogenic hematopoietic stem cell transplantation (allo-HSCT) represents a potent and potentially curative treatment for many hematopoietic malignancies and hematologic disorders in adults and children. The donor-derived immunity, elicited by the stem cell transplant, can prevent disease relapse but is also responsible for the induction of graft-versus-host disease (GVHD). The pathophysiology of acute GVHD is not completely understood yet. In general, acute GVHD is driven by the inflammatory and cytotoxic effect of alloreactive donor T cells. Since several experimental approaches indicate that CD4 T cells play an important role in initiation and progression of acute GVHD, the contribution of the different CD4 T helper (Th) cell subtypes in the pathomechanism and regulation of the disease is a central point of current research. Th lineages derive from naïve CD4 T cell progenitors and lineage commitment is initiated by the surrounding cytokine milieu and subsequent changes in the transcription factor (TF) profile. Each T cell subtype has its own effector characteristics, immunologic function, and lineage specific cytokine profile, leading to the association with different immune responses and diseases. Acute GVHD is thought to be mainly driven by the Th1/Th17 axis, whereas Treg cells are attributed to attenuate GVHD effects. As the differentiation of each Th subset highly depends on the specific composition of activating and repressing TFs, these present a potent target to alter the Th cell landscape towards a GVHD-ameliorating direction, e.g. by inhibiting Th1 and Th17 differentiation. The finding, that targeting of Th1 and Th17 differentiation appears more effective for GVHD-prevention than a strategy to inhibit Th1 and Th17 cytokines supports this concept. In this review, we shed light on the current advances of potent TF inhibitors to alter Th cell differentiation and consecutively attenuate GVHD. We will focus especially on preclinical studies and outcomes of TF inhibition in murine GVHD models. Finally, we will point out the possible impact of a Th cell subset-specific immune modulation in context of GVHD.

OUP accepted manuscript

Graft-versus-host disease (GVHD) is a common complication of allogeneic hematopoietic cell transplantation (HCT) and is associated with significant morbidity and mortality. For many years, there have been few effective treatment options for patients with GVHD. First-line systemic treatment remains corticosteroids, but up to 50% of patients will develop steroid-refractory GVHD and the prognosis for these patients is poor. Elucidation of the pathophysiological mechanisms of acute and chronic GVHD has laid a foundation for novel therapeutic approaches. Since 2017, there have now been 4 approvals by the US Food and Drug Administration (FDA) for GVHD. Ruxolitinib, an oral selective JAK1/2 inhibitor, received FDA approval for the treatment of steroid-refractory acute GVHD in 2019 and remains the only agent approved for acute GVHD. There are currently 3 FDA approvals for the treatment of chronic GVHD: (1) ibrutinib, a BTK inhibitor traditionally used for B-cell malignancies, was the first agent approved for chronic GVHD after failure of one or more lines of systemic therapy, (2) belumosudil, an oral selective inhibitor of ROCK2, for patients with chronic GVHD who received at least 2 prior lines of treatment, and (3) ruxolitinib for chronic GVHD after failure of one or two lines of systemic therapy. In this review, we highlight the clinical data which support these FDA approvals in acute and chronic GVHD with a focus on mechanism of actions, clinical efficacy, and toxicities associated with these agents.

Translational Clinical Strategies for the Prevention of Gastrointestinal Tract Graft Versus Host Disease

Graft versus host disease (GVHD) is the major non-relapse complication associated with allogeneic hematopoietic stem cell transplantation (HSCT). Unfortunately, GVHD occurs in roughly half of patients following this therapy and can induce severe life-threatening side effects and premature mortality. The pathophysiology of GVHD is driven by alloreactive donor T cells that induce a proinflammatory environment to cause pathological damage in the skin, gastrointestinal (GI) tract, lung, and liver during the acute phase of this disease. Recent work has demonstrated that the GI tract is a pivotal target organ and a primary driver of morbidity and mortality in patients. Prevention of this complication has therefore emerged as an important goal of prophylaxis strategies given the primacy of this tissue site in GVHD pathophysiology. In this review, we summarize foundational pre-clinical studies that have been conducted in animal models to prevent GI tract GVHD and examine the efficacy of these approaches upon subsequent translation into the clinic. Specifically, we focus on therapies designed to block inflammatory cytokine pathways, inhibit cellular trafficking of alloreactive donor T cells to the GI tract, and reconstitute impaired regulatory networks for the prevention of GVHD in the GI tract.

Ruxolitinib for Treatment of Steroid-Refractory Graft-versus-Host Disease: Real-World Data from Chinese Patients

Background

Graft-versus-host disease (GVHD) is a main complication following allogeneic hematopoietic stem cell transplantation and is a leading cause of non-relapse-related death. Unsatisfactory response to standard first-line therapy with glucocorticoids is a predictor of a poor prognosis in patients with GVHD. Ruxolitinib is a selective Janus kinases 1/2 inhibitor which has been shown to control acute (a) and chronic (c) GVHD while maintaining graft-versus-tumor effects.

Objective

This study aims to evaluate the efficacy and safety of ruxolitinib in the treatment of steroid-refractory GVHD (SR-GVHD) in a population of Chinese patients.

Methods

We report the results of 55 patients, including 23 patients with aGVHD and 32 patients with cGVHD, who were treated with ruxolitinib as salvage therapy between August, 2017 and December, 2020.

Results

In patients with aGVHD, the overall response rate (ORR) was 86.9%, and the 1-year overall survival (OS) was 82.6% (95% CI, 67.1–98.1%). The 1-year OS was significantly improved in responders than in non-responders (90.0% vs 33.3%, P=0.004). In patients with cGVHD, the ORR was 78.1%, and the 1-year OS was 81.3% (95% CI, 67.8–94.8%). There was no significant difference in the 1-year OS between responders and non-responders (84.0% vs 71.4%, P=0.327). Cytopenia, cytomegalovirus-reactivation and infections were common adverse events, particularly in patients with aGVHD.

Conclusion

Our real-world data from Chinese patients further confirm that ruxolitinib is a safe and effective treatment for SR-GVHD.

Immune Dysregulation and Infectious Complications in MPN Patients Treated With JAK Inhibitors

BCR-ABL1-negative myeloproliferative neoplasms are burdened by a reduced life expectancy mostly due to an increased risk of thrombo-hemorrhagic events, fibrotic progression/leukemic evolution, and infectious complications. In these clonal myeloid malignancies, JAK2V617F is the main driver mutation, leading to an aberrant activation of the Janus kinase-signal transducer and activator of transcription (JAK-STAT) signaling pathway. Therefore, its inhibition represents an attractive therapeutic strategy for these disorders. Several JAK inhibitors have entered clinical trials, including ruxolitinib, the first JAK1/2 inhibitor to become commercially available for the treatment of myelofibrosis and polycythemia vera. Due to interference with the JAK-STAT pathway, JAK inhibitors affect several components of the innate and adaptive immune systems such as dendritic cells, natural killer cells, T helper cells, and regulatory T cells. Therefore, even though the clinical use of these drugs in MPN patients has led to a dramatic improvement of symptoms control, organ involvement, and quality of life, JAK inhibitors–related loss of function in JAK-STAT signaling pathway can be a cause of different adverse events, including those related to a condition of immune suppression or deficiency. This review article will provide a comprehensive overview of the current knowledge on JAK inhibitors’ effects on immune cells as well as their clinical consequences, particularly with regards to infectious complications.

Antibody-drug conjugates plus Janus kinase inhibitors enable MHC-mismatched allogeneic hematopoietic stem cell transplantation

Despite the curative potential of hematopoietic stem cell transplantation (HSCT), conditioning-associated toxicities preclude broader clinical application. Antibody-drug conjugates (ADC) provide an attractive approach to HSCT conditioning that minimizes toxicity while retaining efficacy. Initial studies of ADC conditioning have largely focused on syngeneic HSCT. However, to treat acute leukemias or induce tolerance for solid organ transplantation, this approach must be expanded to allogeneic HSCT (allo-HSCT). Using murine allo-HSCT models, we show that pharmacologic Janus kinase 1/2 (JAK1/2) inhibition combined with CD45- or cKit-targeted ADCs enables robust multilineage alloengraftment. Strikingly, myeloid lineage donor chimerism exceeding 99% was achievable in fully MHC-mismatched HSCT using this approach. Mechanistic studies using the JAK1/2 inhibitor baricitinib revealed marked impairment of T and NK cell survival, proliferation and effector function. NK cells were exquisitely sensitive to JAK1/2 inhibition due to interference with IL-15 signaling. Unlike irradiated mice, ADC-conditioned mice did not develop pathogenic graft-versus-host alloreactivity when challenged with mismatched T cells. Finally, the combination of ADCs and baricitinib balanced graft-versus-host disease and graft-versus-leukemia responses in delayed donor lymphocyte infusion models. Our allo-HSCT conditioning strategy exemplifies the promise of immunotherapy to improve the safety of HSCT for treating hematologic diseases.

T Cell Subsets in Graft Versus Host Disease and Graft Versus Tumor

Allogeneic hematopoietic cell transplantation (allo-HCT) is an essential therapeutic modality for patients with hematological malignancies and other blood disorders. Unfortunately, acute graft-versus-host disease (aGVHD) remains a major source of morbidity and mortality following allo-HCT, which limits its use in a broader spectrum of patients. Chronic graft-versus-host disease (cGVHD) also remains the most common long-term complication of allo-HCT, occurring in reportedly 30-70% of patients surviving more than 100 days. Chronic GVHD is also the leading cause of non-relapse mortality (NRM) occurring more than 2 years after HCT for malignant disease. Graft versus tumor (GVT) is a major component of the overall beneficial effects of allogeneic HCT in the treatment of hematological malignancies. Better understanding of GVHD pathogenesis is important to identify new therapeutic targets for GVHD prevention and therapy. Emerging data suggest opposing roles for different T cell subsets, e.g., IFN-γ producing CD4+ and CD8+ T cells (Th1 and Tc1), IL-4 producing T cells (Th2 and Tc2), IL-17 producing T cells (Th17 and Tc17), IL-9 producing T cells (Th9 and Tc9), IL-22 producing T cells (Th22), T follicular helper cells (Tfh), regulatory T-cells (Treg) and tissue resident memory T cells (Trm) in GVHD and GVT etiology. In this review, we first summarize the general description of the cytokine signals that promote the differentiation of T cell subsets and the roles of these T cell subsets in the pathogenesis of GVHD. Next, we extensively explore preclinical findings of T cell subsets in both GVHD/GVT animal models and humans. Finally, we address recent findings about the roles of T-cell subsets in clinical GVHD and current strategies to modulate T-cell differentiation for treating and preventing GVHD in patients. Further exploring and outlining the immune biology of T-cell differentiation in GVHD that will provide more therapeutic options for maintaining success of allo-HCT.

Janus Kinase Inhibitors and Cell Therapy

Cellular therapies such as allogeneic hematopoietic stem cell transplantation (HSCT) and immune-effector cell therapy (IECT) continue to have a critical role in the treatment of patients with high risk malignancies and hematologic conditions. These therapies are also associated with inflammatory conditions such as graft-versus-host disease (GVHD) and cytokine release syndrome (CRS) which contribute significantly to the morbidity and mortality associated with these therapies. Recent advances in our understanding of the immunological mechanisms that underly GVHD and CRS highlight an important role for Janus kinases (JAK). JAK pathways are important for the signaling of several cytokines and are involved in the activation and proliferation of several immune cell subsets. In this review, we provide an overview of the preclinical and clinical evidence supporting the use of JAK inhibitors for acute and chronic GVHD and CRS.

Predictors of Transplant-Associated Thrombotic Microangiopathy in Patients With Overlap or Chronic Graft-vs-Host-Disease

BACKGROUND

Recent data suggest that novel biologic agents are associated with increased risk of thrombotic microangiopathy (TMA). Ruxolitinib, an approved treatment for graft-vs-host-disease (GVHD), has been associated with thrombocytopenia of unclear etiology.

METHODS

We investigated factors and outcomes associated with transplant-associated thrombotic microangiopathy (TA-TMA) in patients with GVHD. We retrospectively enrolled consecutive allogeneic hematopoietic cell transplantation recipients with overlap or chronic GVHD at our Joint Accreditation Committee ISCT-Europe & EBMT-accredited unit (January 2016-June 2019). Ruxolitinib has been administered off-label since 2016.

RESULTS

Among 160 patients with GVHD, 18 were diagnosed with TA-TMA. TA-TMA developed at a median of 150 posttransplant days (range, 98-3013). Among pre- and posttransplant factors, TA-TMA was associated only with ruxolitinib administration and severe GVHD. Interestingly, these 2 variables did not correlate with each other. In the multivariate analysis, both were independent predictors of TA-TMA. Time-dependent analysis confirmed ruxolitinib's association with TA-TMA. With a follow-up of 38.4 months (4.6-83.9) in surviving patients, 5-year overall survival was 52.9%, independently predicted by TA-TMA, severe acute GVHD, and CD34+ cells infused. Ruxolitinib was not associated with survival outcomes.

CONCLUSIONS

Our data suggest that ruxolitinib and GVHD severity are associated with TA-TMA. Given the expanding use of ruxolitinib in GVHD and ongoing trials on chronic GVHD, further studies are warranted to confirm these findings.

The Effects of Interferons on Allogeneic T Cell Response in GVHD: The Multifaced Biology and Epigenetic Regulations

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a potentially curative therapy for hematological malignancies. This beneficial effect is derived mainly from graft-versus-leukemia (GVL) effects mediated by alloreactive T cells. However, these alloreactive T cells can also induce graft-versus-host disease (GVHD), a life-threatening complication after allo-HSCT. Significant progress has been made in the dissociation of GVL effects from GVHD by modulating alloreactive T cell immunity. However, many factors may influence alloreactive T cell responses in the host undergoing allo-HSCT, including the interaction of alloreactive T cells with both donor and recipient hematopoietic cells and host non-hematopoietic tissues, cytokines, chemokines and inflammatory mediators. Interferons (IFNs), including type I IFNs and IFN-γ, primarily produced by monocytes, dendritic cells and T cells, play essential roles in regulating alloreactive T cell differentiation and function. Many studies have shown pleiotropic effects of IFNs on allogeneic T cell responses during GVH reaction. Epigenetic mechanisms, such as DNA methylation and histone modifications, are important to regulate IFNs’ production and function during GVHD. In this review, we discuss recent findings from preclinical models and clinical studies that characterize T cell responses regulated by IFNs and epigenetic mechanisms, and further discuss pharmacological approaches that modulate epigenetic effects in the setting of allo-HSCT.

Efficiency and Toxicity of Ruxolitinib as a Salvage Treatment for Steroid-Refractory Chronic Graft-Versus-Host Disease

Graft-versus-host disease (GVHD), especially steroid-refractory GVHD, remains a life-threatening complication after hematopoietic stem cell transplantation (HSCT). The effect of the JAK1/2 kinase inhibitor ruxolitinib on treating steroid-refractory acute GVHD has been verified by the REACH1/2 study; however, its safety and efficacy in patients with steroid-refractory chronic GVHD (SR-cGVHD) remain unclear. In this retrospective study, 70 patients received ruxolitinib as a salvage therapy for SR-cGVHD. Twenty-four weeks after ruxolitinib treatment, the overall response rate (ORR) was 74.3% (52/70), including 34 patients who achieved complete remission (CR) and 18 who achieved partial remission (PR). The main adverse event was cytopenia, which occurred in 51.4% (36/70) of patients. After ruxolitinib treatment, the percentage of CD4 cells increased from 18.20% to 23.22% (P<0.001), while the percentages of NK (CD16⁺CD56⁺) cells and regulatory T cells (CD4⁺CD127 ^± CD25⁺) decreased (P<0.001, P<0.001). Among the B cell subsets, the proportion of total B cells approximately tripled from 3.69% to 11.16% (P<0.001). Moreover, we observed a significant increase in IL-10 levels after ruxolitinib treatment (P=0.025) and a remarkable decrease in levels of suppression of tumorigenicity 2 (ST2) from 229.90 ng/ml to 72.65 ng/ml. The median follow-up after the initiation of ruxolitinib treatment was 401 (6-1076) days. The estimated one-year overall survival rate of the whole group was 66.0% (54.4-77.6%, 95% CI), and the one-year overall survival rate of patients with mild and moderate cGVHD was 69.6% (57.4-81.8%, 95% CI), which was better than that of patients with severe cGVHD (31.3%, 0.0-66.2%, 95% CI) (P=0.002). Patients who achieved a CR and PR achieved better survival outcomes (84.5%, 73.9-95.1%, 95% CI) than those who showed NR to ruxolitinib treatments (16.7%, 0-34.3%, 95% CI) (P<0.001). At the final follow-up, cGVHD relapse occurred in six patients after they reduced or continued their ruxolitinib doses. Collectively, our results suggest that ruxolitinib is potentially a safe and effective treatment for SR-cGVHD.

Salvage Therapy With Low-Dose Ruxolitinib Leads to a Significant Improvement in Bronchiolitis Obliterans Syndrome in Patients With cGVHD After Allogeneic Hematopoietic Stem Cell Transplantation

Bronchiolitis obliterans syndrome (BOS) is a life-threatening pulmonary manifestation of chronic graft versus host disease (cGVHD) post-allogeneic hematopoietic stem cell transplantation (HSCT), without clear standard of care. This study included 30 patients undergoing an allogeneic HSCT for a hematological malignancy and the outcomes with post-HSCT BOS treated with ruxolitinib as a salvage treatment were reviewed. After a median duration of ruxolitinib therapy of 9.25 (1.5–27) months, the best overall response (BOR) rate was 66.7%: three patients (10.0%) achieved complete remission, and 17 (56.7%) achieved partial remission. The median time from initiation of ruxolitinib to achieve the best responses was 3 months. Since initiating ruxolitinib, forced expiratory volume in 1 s of predicted (FEV1%pred) slightly increased after 3 and 6 months compared with measurements before ruxolitinib in responders. Only FEV1%pred mild decline before ruxolitinib with a ratio ≤15% was an independent predictor to achieve a response to ruxolitinib. Eleven patients (36.7%) had severe pulmonary infection of ≥3 grade. Following a median follow-up of 318 days after ruxolitinib, the 2-years incidence of nonrelapse mortality and 2-years overall survival rate after ruxolitinib among patients with BOS was 25.1 and 62.6%, respectively. Ruxolitinib is a promising treatment option to improve the prognosis of post-HSCT BOS.

Interfering With Inflammation: Heterogeneous Effects of Interferons in Graft-Versus-Host Disease of the Gastrointestinal Tract and Inflammatory Bowel Disease

The intestine can be the target of several immunologically mediated diseases, including graft-versus-host disease (GVHD) and inflammatory bowel disease (IBD). GVHD is a life-threatening complication that occurs after allogeneic hematopoietic stem cell transplantation. Involvement of the gastrointestinal tract is associated with a particularly high mortality. GVHD development starts with the recognition of allo-antigens in the recipient by the donor immune system, which elicits immune-mediated damage of otherwise healthy tissues. IBD describes a group of immunologically mediated chronic inflammatory diseases of the intestine. Several aspects, including genetic predisposition and immune dysregulation, are responsible for the development of IBD, with Crohn’s disease and ulcerative colitis being the two most common variants. GVHD and IBD share multiple key features of their onset and development, including intestinal tissue damage and loss of intestinal barrier function. A further common feature in the pathophysiology of both diseases is the involvement of cytokines such as type I and II interferons (IFNs), amongst others. IFNs are a family of protein mediators produced as a part of the inflammatory response, typically to pathogens or malignant cells. Diverse, and partially paradoxical, effects have been described for IFNs in GVHD and IBD. This review summarizes current knowledge on the role of type I, II and III IFNs, including basic concepts and controversies about their functions in the context of GVHD and IBD. In addition, therapeutic options, research developments and remaining open questions are addressed.

A phase 1 trial of itacitinib, a selective JAK1 inhibitor, in patients with acute graft-versus-host disease

Acute graft-versus-host disease (aGVHD) following allogeneic hematopoietic cell transplantation (HCT) is a primary cause of nonrelapse mortality and a major barrier to successful transplant outcomes. Itacitinib is a Janus kinase (JAK)1-selective inhibitor that has demonstrated efficacy in preclinical models of aGVHD. We report results from the first registered study of a JAK inhibitor in patients with aGVHD. This was an open-label phase 1 study enrolling patients aged ≥18 years with first HCT from any source who developed grade IIB to IVD aGVHD. Patients with steroid-naive or steroid-refractory aGVHD were randomized 1:1 to itacitinib 200 mg or 300 mg once daily plus corticosteroids. The primary endpoint was safety and tolerability; day 28 overall response rate (ORR) was the main secondary endpoint. Twenty-nine patients (200 mg, n = 14; 300 mg, n = 15) received ≥1 dose of itacitinib and were included in safety and efficacy assessments. One dose-limiting toxicity was reported (grade 3 thrombocytopenia attributed to GVHD progression in a patient receiving 300 mg itacitinib with preexisting thrombocytopenia). The most common nonhematologic treatment-emergent adverse event was diarrhea (48.3%, n = 14); anemia occurred in 11 patients (38%). ORR on day 28 for all patients in the 200-mg and 300-mg groups was 78.6% and 66.7%, respectively. Day 28 ORR was 75.0% for patients with treatment-naive aGVHD and 70.6% in those with steroid-refractory aGVHD. All patients receiving itacitinib decreased corticosteroid use over time. In summary, itacitinib was well tolerated and demonstrated encouraging efficacy in patients with steroid-naive or steroid-refractory aGVHD, warranting continued clinical investigations. This trial was registered at www.clinicaltrials.gov as #NCT02614612.

GVHD Prophylaxis 2020

Graft-vs. host disease (GVHD), both acute and chronic are among the chief non-relapse complications of allogeneic transplantation which still cause substantial morbidity and mortality despite significant advances in supportive care over the last few decades. The prevention of GVHD therefore remains critical to the success of allogeneic transplantation. In this review we briefly discuss the pathophysiology and immunobiology of GVHD and the current standards in the field which remain centered around calcineurin inhibitors. We then discuss important translational advances in GVHD prophylaxis, approaching these various platforms from a mechanistic standpoint based on the pathophysiology of GVHD including in-vivo and ex-vivo T-cell depletion alongwith methods of selective T-cell depletion, modulation of T-cell co-stimulatory pathways (checkpoints), enhancing regulatory T-cells (Tregs), targeting T-cell trafficking as well as cytokine pathways. Finally we highlight exciting novel pre-clinical research that has the potential to translate to the clinic successfully. We approach these methods from a pathophysiology based perspective as well and touch upon strategies targeting the interaction between tissue damage induced antigens and T-cells, regimen related endothelial toxicity, T-cell co-stimulatory pathways and other T-cell modulatory approaches, T-cell trafficking, and cytokine pathways. We end this review with a critical discussion of existing data and novel therapies that may be transformative in the field in the near future as a comprehensive picture of GVHD prophylaxis in 2020. While calcineurin inhibitors remain the standard, post-transplant eparinsphamide originally developed to facilitate haploidentical transplantation is becoming an attractive alternative to traditional calcinuerin inhibitor based prophylaxis due to its ability to reduce severe forms of acute and chronic GVHD without compromising other outcomes, even in the HLA-matched setting. In addition T-cell modulation, particularly targeting some important T-cell co-stimulatory pathways have resulted in promising outcomes and may be a part of GVHD prophylaxis in the future. Novel approaches including targeting early events in GVHD pathogenesis such as interactions bvetween tissue damage associated antigens and T-cells, endothelial toxicity, and T-cell trafficking are also promising and discussed in this review. GVHD prophylaxis in 2020 continues to evolve with novel exicitng therapies on the horizon based on a more sophisticated understanding of the immunobiology of GVHD.

Outcomes of methotrexate-associated lymphoproliferative disorders in rheumatoid arthritis patients treated with disease-modifying anti-rheumatic drugs

Recently, the use of targeted synthetic or biological disease-modifying anti-rheumatic drugs (ts/bDMARDs) in addition to conventional synthetic (cs)DMARDs including methotrexate (MTX) for rheumatoid arthritis (RA) has increased. However, whether ts/bDMARDs are associated with the development and clinicopathological features of MTX-associated lymphoproliferative disorder (MTX-LPD) in patients with RA remains unknown. Therefore, we evaluated the clinical outcomes of 121 patients with MTX-LPD. Results showed that prior use of ts/bDMARDs was not associated with the different histopathological subtypes of MTX-LPD. Patients with polymorphic-type LPD had a better event-free survival than those with diffuse large B-cell lymphoma (DLBCL), classical Hodgkin lymphoma and peripheral T-cell lymphoma. The pathological subtype of lymphoma could predict the clinical outcome of MTX-LPD. In patients with DLBCL, the use of tumour necrosis factor-alpha (TNF-α) inhibitors prior to MTX-LPD onset was associated with a higher non-relapse mortality. Further, patients with RA previously treated with Janus kinase (JAK) inhibitors more commonly required chemotherapy than those treated with csDMARDs alone, indicating disease aggressiveness. Hence, special caution should be observed when managing patients with MTX-LPD previously treated with JAK or TNF-α inhibitors for RA.

Preclinical evaluation of JAK1/2 inhibition by ruxolitinib in a murine model of chronic graft-versus-host disease

The objective of this study was to examine the therapeutic effect of ruxolitinib, an orally administered selective Janus kinase (JAK) 1/2 inhibitor, on chronic graft-versus-host disease (cGVHD) using a murine model of sclerodermatous GVHD (scl-GVHD). Compared with scl-GVHD controls, ruxolitinib-treated recipients had scl-GVHD of significantly attenuated clinical and pathological severity in the skin and decreased frequencies of effector cells, CD4⁺ T cells, and CD11b⁺ macrophage/monocytes. Regulatory CD4⁺ Foxp3⁺ T cells were expanded whereas interferon-γ (IFN-γ)-producing CD4⁺ T cells were significantly decreased in ruxolitinib-treated recipients. Ruxolitinib suppressed not only the production of IFN-γ from CD4⁺ T cells and monocyte chemoattractant protein 1 (MCP-1) from CD11b⁺ macrophage/monocytes, but also the proliferation of these cells in vitro. Levels of both cytokines (IFN-γ and MCP-1) were also reduced in the spleen and skin of ruxolitinib-treated recipients in vivo. IFN-γ-induced MCP-1 production and migration of RAW 264.7 cells, a macrophage cell line, were inhibited by ruxolitinib. However, supplementation with MCP-1 restored this effect of ruxolitinib. In addition, blocking JAK-STAT signaling using ruxolitinib reduced the activation of STAT1 in stimulated immune effector cells. Taken together, these results suggest that ruxolitinib can prevent scl-GVHD by suppressing IFN-γ produced by T cells and MCP-1 expression in macrophage/monocytes via inhibition of JAK-STAT signaling.

Inflammation, immunity and potential target therapy of SARS-COV-2: A total scale analysis review

Coronavirus disease-19 (COVID-19) is a complex disease that causes illness ranging from mild to severe respiratory problems. It is caused by a novel coronavirus SARS-CoV-2 (Severe acute respiratory syndrome coronavirus-2) that is an enveloped positive-sense single-stranded RNA (+ssRNA) virus belongs to coronavirus CoV family. It has a fast-spreading potential worldwide, which leads to high mortality regardless of lows death rates. Now some vaccines or a specific drug are approved but not available for every country for disease prevention and/or treatment. Therefore, it is a high demand to identify the known drugs and test them as a possible therapeutic approach. In this critical situation, one or more of these drugs may represent the only option to treat or reduce the severity of the disease, until some specific drugs or vaccines will be developed and/or approved for everyone in this pandemic. In this updated review, the available repurpose immunotherapeutic treatment strategies are highlighted, elucidating the crosstalk between the immune system and SARS-CoV-2. Despite the reasonable data availability, the effectiveness and safety of these drugs against SARS-CoV-2 needs further studies and validations aiming for a better clinical outcome.

AML and the art of remission maintenance

Relapse in acute myeloid leukemia (AML) is common, especially in older patients, and there is currently no standard of care maintenance therapy for those who achieve complete remission. Finding effective, tolerable maintenance therapy to prolong remission has been a goal for decades, but early clinical trials testing a variety of agents demonstrated disappointing results with no overall survival benefit. CC-486, an oral hypomethylating agent, was recently approved in the United States for maintenance treatment in patients with AML in first remission following chemotherapy. A number of ongoing studies are assessing various therapeutics in the maintenance setting, including other hypomethylating agents, targeted small-molecule inhibitors, monoclonal antibodies, and immunomodulators. New strategies are needed to identify patients most likely to benefit from maintenance therapy, including those for whom a preemptive approach reliant on monitoring of measurable residual disease would be advantageous.

The Effectiveness of Ruxolitinib for Acute/Chronic Graft-versus-Host Disease in Children: A Retrospective Study

Objective

This study aimed to evaluate the effectiveness of Ruxolitinib for acute/chronic graft-versus-host disease in children.

Methods

This study was a retrospective trial. We analyzed the clinical characteristics of children who responded poorly to previous treatment for graft-versus-host disease (GVHD) and received ruxolitinib treatment after allogeneic hematopoietic stem cell transplantation (allo-HSCT) as an additional or replacement therapy.

Results

A total of 53 patients were analyzed: aGVHD and cGVHD. The overall response rate (ORR) to ruxolitinib was 75.5%. The ORR was 64.7% (11/17) in the aGVHD group including 6, 5, and 6 patients with partial responses (PRs), complete responses (CRs), and treatment failure, respectively. The ORR was 80.6% (29/36) in the cGVHD group including 10 with CRs and 19 with PRs. Five and 2 patients showed no response and treatment failure, respectively. Four and 14 patients were GVHD recurrence in aGVHD and cGVHD respectively. A total of 14 patients (39%) discontinued steroids and 8 patients (22.2%) reduced steroids. The incidence of obvious adverse events was 94.1% (16/17) in the aGVHD group, which was higher than that in the cGVHD group. Meanwhile, the prognosis of children with cGVHD was superior to that of children with aGVHD after treatment with ruxolitinib. During the ruxolitinib treatment, only 1 patient suffered a relapse of the primary tumor. Eleven patients also suffered transplantation-associated thrombotic microangiopathy (TA-TMA) after allo-HSCT.

Conclusion

Pediatric patients with GVHD (especially cGVHD) responded well to ruxolitinib treatment. Ruxolitinib can also be used as an alternative treatment for patients with TMA.

Risk of infections in patients with myeloproliferative neoplasms-a population-based cohort study of 8363 patients

Infections are a common complication in patients with many hematologic malignancies, however, whether patients with myeloproliferative neoplasms (MPN) also are at an increased risk of infections is largely unknown. To assess the risk of serious infections, we performed a large population-based matched cohort study in Sweden including 8 363 MPN patients and 32,405 controls using high-quality registers between the years 1992-2013 with follow-up until 2015. The hazard ratio (HR) of any infection was 2.0 (95% confidence interval 1.9-2.0), of bacterial infections 1.9 (1.8-2.0), and of viral infections 2.1 (1.9-2.3). One of the largest risk increases was that of sepsis, HR 2.6 (2.4-2.9). The HR of any infection was highest in primary myelofibrosis 3.7 (3.2-4.1), and significantly elevated in all MPN subtypes; 1.7 (1.6-1.8) in polycythemia vera and 1.7 (1.5-1.8) in essential thrombocythemia. There was no significant difference in risk of infections between untreated patients and patients treated with hydroxyurea or interferon-α during the years 2006-2013. These novel findings of an overall increased risk of infections in MPN patients, irrespective of common cytoreductive treatments, suggest the increased risk of infection is inherent to the MPN.

Efficiency and Toxicity of Ruxolitinib as the Salvage Treatment in Steroid-Refractory Acute Graft-Versus-Host Disease after Haplo-Identical Stem Cell Transplantation

Haplo-identical stem cell transplantation (haplo-SCT) for hematological malignancies has ushered in a new era in which everyone has a potential donor. However, the occurrence of steroid-refractory acute graft-versus-host disease (SR-aGVHD), with no priority among second-line therapies, leads to late mortality after haplo-SCT. Ruxolitinib is the first drug recommended for SR-aGVHD. Here, we report the outcome data from 40 patients after haplo-SCT following the Beijing Protocol who had received ruxolitinib as a salvage therapy for grades II to IV SR-aGVHD in our center between November 2017 and May 2019. The overall response rate was 85% (34/40; 95% confidence interval [CI], 73.4% to 96.6%), including 25 patients with complete response. The median time to first response was 10 days. The levels of inflammatory cytokines and T cell activation declined, and the percentage of regulatory T cells increased. The rate of GVHD relapse was 26.5% (9/34; 95% CI, 10.8% to 42.1%) in responders. Cytomegalovirus reactivation and cytopenia were the major adverse events after ruxolitinib was begun (57.5% and 60%, respectively). The 6-month overall survival estimate was 56.8% (95% CI, 41.5% to 72.1%), and the event-free survival was 45% (95% CI, 29.7% to 60.3%). Liver GVHD was associated with a worse response rate and poor survival. Collectively, ruxolitinib could be an effective treatment for SR-aGVHD patients after haplo-SCT.