FDA Approval Summary: Ruxolitinib for Treatment of Steroid-Refractory Acute Graft-Versus-Host Disease

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 graft-versus-host disease: a retrospective analysis

Steroid-refractory acute graft-versus-host disease (aGvHD) is a serious complication after allogeneic hematopoietic stem cell transplantation, associated with significant mortality. Ruxolitinib was the first drug approved for aGvHD, based on results of the REACH2 trial; however, real-world data are limited. We retrospectively analyzed the safety and efficacy of ruxolitinib for treatment of aGvHD at our center from March 2016 to August 2022 and assessed biomarkers of risk. We identified 49 patients receiving ruxolitinib as second- (33/49), third- (11/49), fourth- (3/49), or fifth-line (2/49) treatment. Ruxolitinib was started on median day 11 (range, 7-21) after aGvHD onset; median duration of administration was 37 days (range, 20-86), with 10 patients continuing treatment at last follow-up. Median follow-up period was 501 days (range, 95-905). In the primary analysis at the 1-month assessment, overall response rate was 65%, and failure-free survival was 78%. Infectious complications ≥ CTCAE Grade III were observed in 10/49 patients within 1-month followup. Patients responding to ruxolitinib therapy required fewer steroids and exhibited lower levels of the serum biomarkers regenerating islet-derived protein 3-alpha, suppression of tumorigenicity 2, and the Mount Sinai Acute GVHD International Consortium algorithm probability. A univariate regression model revealed steroid-dependent aGvHD as a significant predictor of better response to ruxolitinib. Within 6-months follow-up, four patients experienced recurrence of underlying malignancy, and eight died due to treatment-related mortality. Overall, ruxolitinib was welltolerated and showed response in heavily pretreated patients, with results comparable to those of the REACH2 trial. Biomarkers may be useful predictors of response to ruxolitinib.

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

ABSTRACT

The significance of biomarkers in second-line treatment for acute graft-versus-host disease (GVHD) has not been well characterized. We analyzed clinical data and serum samples at the initiation of second-line systemic treatment of acute GVHD from 167 patients from 17 centers of the Mount Sinai Acute GVHD International Consortium (MAGIC) between 2016 and 2021. Sixty-two patients received ruxolitinib-based therapy, whereas 102 received other systemic agents. In agreement with prospective trials, ruxolitinib resulted in a higher day 28 (D28) overall response Frate than nonruxolitinib therapies (55% vs 31%, P = .003) and patients who received ruxolitinib had significantly lower nonrelapse mortality (NRM) than those who received nonruxolitinib therapies (point estimates at 2-year: 35% vs 61%, P = .002). Biomarker analyses demonstrated that the benefit from ruxolitinib was observed only in patients with low MAGIC algorithm probabilities (MAPs) at the start of second-line treatment. Among patients with a low MAP, those who received ruxolitinib experienced significantly lower NRM than those who received nonruxolitinib therapies (point estimates at 2-year: 12% vs 41%, P = .016). However, patients with high MAP experienced high NRM regardless of treatment with ruxolitinib or nonruxolitinib therapies (point estimates at 2-year: 67% vs 80%, P = .65). A landmark analysis demonstrated that the relationship between the D28 response and NRM largely depends on the MAP level at the initiation of second-line therapy. In conclusion, MAP measured at second-line systemic treatment for acute GVHD predicts treatment response and NRM. The outcomes of patients with high MAP are poor regardless of treatment choice, and ruxolitinib appears to primarily benefit patients with low MAP.

Ruxolitinib in steroid-refractory acute graft-vs-host disease: Japanese subgroup analysis of the randomized REACH2 trial

Acute graft-versus-host disease (aGvHD) is a major complication after allogeneic hematopoietic stem cell transplantation in Japan and other countries. Nearly one-third of patients do not respond to standard systemic steroid therapy and no standard second-line treatment has been established in Japan. We report efficacy and safety findings of ruxolitinib versus best available therapy (BAT) from a subgroup analysis of the international, phase 3 REACH2 study in Japanese patients with steroid-refractory aGvHD. The primary endpoint was overall response rate (ORR) at day 28. Overall, 9 patients received ruxolitinib and 21 received BAT. The ORR at day 28 (88.9% vs 52.4%) and durable ORR at day 56 (66.7% vs 28.6%) were higher with ruxolitinib versus BAT. The estimated cumulative incidence of loss of response at 6 months was 12.5% with ruxolitinib and 18.2% with BAT. The median failure-free survival was longer with ruxolitinib versus BAT (2.73 vs 1.25 months). The most common adverse events up to day 28 in the ruxolitinib and BAT groups were anemia (55.6% vs 19.0%) and thrombocytopenia (44.4% vs 4.8%, respectively). Ruxolitinib showed better efficacy outcomes and a consistent safety profile compared with BAT in the Japanese subgroup, and the findings were consistent with overall study results.

Efficacy and safety of ruxolitinib in the treatment of chronic graft-versus-host disease: a retrospective analysis

Steroid-refractory chronic graft-versus-host disease (cGvHD) is associated with significant morbidity and mortality, with ruxolitinib being the first drug approved for its treatment. We retrospectively analyzed the safety and efficacy of ruxolitinib for treatment of cGvHD at our center between 07/2015 and 12/2022 and identified 48 patients receiving ruxolitinib as second (18/48) or advanced (30/48) treatment line. Ruxolitinib was started on median day 340 (range 119-595) after cGvHD onset; median duration of administration was 176 (range, 79-294) days with 16/48 patients continuing treatment at last follow-up. National Institutes of Health organ grading and the intensity of immunosuppression were assessed at the start of ruxolitinib treatment and repeated after 1, 3, 6, and 12 months. Response assessment was terminated at the start of any additional new immunosuppressant treatment. The median time of follow-up was 582 (range, 104-1161) days. At the primary analysis after six months on ruxolitinib treatment, the overall response rate was 33%, and failure-free survival was 58%. Infectious adverse events ≥ CTCAE grade III were observed in 10/48 patients. The response rate was not associated with the severity of cGvHD, number of previous treatment lines, or number of additional agents combined with ruxolitinib applying a univariate regression model. At the time of the 12-month follow-up, four patients experienced recurrence of the underlying malignancy and two patients had experienced non-relapse-related mortality. Overall, ruxolitinib was relatively well-tolerated and showed outcomes comparable to the REACH3 trial in a heavily pretreated patient population.

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.

Two-year safety outcomes of iPS cell-derived mesenchymal stromal cells in acute steroid-resistant graft-versus-host disease

The first completed clinical trial of induced pluripotent stem cell (iPS cell)-derived cells was conducted in 15 participants with steroid-resistant acute graft-versus-host disease. After intravenous infusion of mesenchymal stromal cells (CYP-001 derived from a clone of human iPS cells), we reported the safety, tolerability and efficacy within the primary evaluation period at day 100. We now report results at the 2-year follow-up: 9 of 15 (60%) participants survived, which compares favorably with previously reported outcomes in studies of steroid-resistant acute graft-versus-host disease. Causes of death were complications commonly observed in recipients of allogeneic hematopoietic stem cell transplantation, and not considered by the investigators to be related to CYP-001 treatment. There were no serious adverse events, tumors or other safety concerns related to CYP-001. In conclusion, systemic delivery of iPS cell-derived cells was safe and well tolerated over 2 years of follow-up, with sustained outcomes up to 2 years after the first infusion. ClinicalTrials.gov registration: NCT02923375 .

Real-world experience with ruxolitinib therapy for steroid-refractory acute graft versus host disease

Acute graft versus host disease (aGVHD) is a complication of allogeneic hematopoietic stem cell transplant (HCT) and is associated with significant morbidity and mortality. Steroid refractory aGVHD (SR-aGVHD) carries a particularly grim prognosis. Ruxolitinib has shown promise for treatment of SR-aGVHD in a phase 3 trial; however, safety and efficacy data outside of the clinical trial setting is lacking. We performed a multicenter retrospective study to examine the response to ruxolitinib and its efficacy in patients with SR-aGVHD. We included 59 patients treated with ruxolitinib for SR-aGVHD between 2015 and 2022. Of these 59 patients, 36 patients (61.0%) achieved a complete (CR) or partial response (PR) at 28 days, while 31 patients (52.5%) obtained a CR/PR at day 56. Patients that achieved a CR or PR at day 28 had a higher rate of overall survival (OS; 69.2%), compared with patients that did not (31.6%; p = 0.037). OS at 12 months was 41.5%, with a median OS duration of 5.3 months. Failure free survival (FFS) at 12 months was 29.1%, with a median FFS of 2.6 months. Overall, this real-world experience data support ruxolitinib as the standard of care for SR-aGVHD in a non-controlled trial population.

Efficacy and Safety in Early application of Ruxolinitib for high-risk: Acute lymphoblastic leukemia to prevent GVHD and recurrence after allogeneic hematopoietic stem cell transplantation

BACKGROUND

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) has been identified as the potentially curative treatment for high-risk acute lymphoblastic leukemia (ALL) in adult patients. However, relapse of the disease and/or development of graft-versus-host disease (GVHD) remain to be the most common barriers for successful allo-HSCT. Preclinical studies showed that ruxolitinib, a Janus tyrosine kinase (Jak)1 and Jak2 inhibitor, has a selective anti-GVHD effects while preserving a potent graft-versus-leukemia (GVL) effect. Our study aimed to investigate the efficacy and safety in early application of ruxolitinib for the high-risk ALL patients to prevent GVHD.

METHODS

There were eight patients undergoing allo-HSCT at the Bone Marrow Transplantation Center of the Third Xiangya Hospital of Central South University between April 2020 and April 2021. Ruxolitinib (5-10 mg twice daily) was administered early (median time: 45 days) after stem cell infusion.

RESULTS

After a median follow-up of 14 months (range from 8 to 18 months), the ALL disease relapse occurred in two cases. Among all eight patients, two of them developed grade I/II acute (a) GVHD, while no patient developed grade III/IV aGVHD, and one patient developed chronic (c) GVHD. As for the virus activation, no patient developed EBV activation or EBV related lymphoproliferative disease, and three patients developed CMV activation. Our results suggest that the early application of ruxolitinib could safely and effectively prevent the occurrence of GVHD after allo-HSCT for the high-risk ALL patients. However, it may have a limited effect on preventing the recurrence of high-risk ALL and thus may require additional therapy with other anti-relapse drugs.

CONCLUSIONS

Our preliminary observations suggest that an early application of ruxolitinib can safely and effectively prevent the occurrence of GVHD after allo-HSCT for the high-risk ALL patients. However, ruxolitinib may have a limited effect on preventing the ALL recurrence of high-risk patients.

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.

Exploring Novel Frontiers: Leveraging STAT3 Signaling for Advanced Cancer Therapeutics

Signal Transducer and Activator of Transcription 3 (STAT3) plays a significant role in diverse physiologic processes, including cell proliferation, differentiation, angiogenesis, and survival. STAT3 activation via phosphorylation of tyrosine and serine residues is a complex and tightly regulated process initiated by upstream signaling pathways with ligand binding to receptor and non-receptor-linked kinases. Through downstream deregulation of target genes, aberrations in STAT3 activation are implicated in tumorigenesis, metastasis, and recurrence in multiple cancers. While there have been extensive efforts to develop direct and indirect STAT3 inhibitors using novel drugs as a therapeutic strategy, direct clinical application remains in evolution. In this review, we outline the mechanisms of STAT3 activation, the resulting downstream effects in physiologic and malignant settings, and therapeutic strategies for targeting STAT3. We also summarize the pre-clinical and clinical evidence of novel drug therapies targeting STAT3 and discuss the challenges of establishing their therapeutic efficacy in the current clinical landscape.

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.

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.

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.

[Humanized anti-CD25 monoclonal antibody as a salvage therapy for steroid-refractory acute graft-versus-host disease after hematopoietic stem cell transplantation]

Objective: To investigate the efficacy of humanized anti-CD25 monoclonal antibody for steroid-refractory acute graft-versus-host disease (SR-aGVHD) in allogeneic hematopoietic stem cell transplantation (allo-HSCT) recipients. Methods: A total of 64 patients with SR-aGVHD between June 2019 and October 2020 in Suchow Hopes Hematology Hospital were enrolled in this study. Humanized anti-CD25 monoclonal antibodies 1 mg·kg(-1)·d(-1) were administered on days 1, 3, and 8, and then once per week according to the disease progression. Efficacy was assessed at days 7, 14, and 28 after humanized anti-CD 25 treatment. Results: Of the 64 patients with a median age of 31 (15-63) years, 38 (59.4%) were male and 26 (40.6%) were female. The overall response (OR) rate of the humanized CD25 monoclonal antibody in 64 patients with SR-aGVHD on days 7, 14, and 28 were 48.4% (31/64), 53.1% (34/64), and 79.7% (51/64), respectively. Liver involvement is an independent risk factor for poor efficacy of humanized CD25 monoclonal antibody for SR-aGVHD at day 28 (OR=9.588, 95% CI 0.004-0.291, P=0.002). The median follow-up time for all patients was 17.1 (0.2-50.8) months from the start of humanized CD25 monoclonal antibody therapy. The 1- and 2-year OS rates were 63.2% (95% CI 57.1% -69.3%) and 52.6% (95% CI 46.1% -59.1%), respectively. The 1- and 2-year DFS rates were 58.4% (95% CI 52.1% -64.7%) and 49.8% (95% CI 43.4% -56.2%), respectively. The 1- and 2-year NRM rates were 28.8% (95% CI 23.1% -34.5%) and 32.9% (95% CI 26.8% -39.0%), respectively. The results of the multifactorial analysis showed that liver involvement (OR=0.308, 95% CI 0.108-0.876, P=0.027) and GVHD grade Ⅲ/Ⅳ (OR=9.438, 95% CI 1.211-73.577, P=0.032) were independent risk factors for OS. Conclusion: Humanized CD25 monoclonal antibody has good efficacy and safety for SR-aGVHD. This study shows that SR-aGVHD with pretreatment grade Ⅲ/Ⅳ GVHD and GVHD involving the liver has poor efficacy and prognosis and requires early intervention.

Ruxolitinib Treatment of Steroid-Refractory Graft-versus-Host Disease in Children: A Case Series and Review of the Literature

BACKGROUND

Ruxolitinib has been increasingly used in the treatment of steroid-refractory graft-versus-host disease (SR-GVHD) in allogeneic hematopoietic stem cell transplantation (allo-HSCT) patients. However, there are limited data on the use of ruxolitinib in children.

OBJECTIVE

This study aimed to assess the efficacy and toxicity of ruxolitinib in the treatment of SR-GVHD in children.

PATIENTS AND METHODS

Data of patients who suffered from SR-GVHD after allo-HSCT and received ruxolitinib treatment between June 2018 and December 2020 at our center were analyzed retrospectively. The characteristics of patients, the dosage of ruxolitinib, the response, toxicity, and the survival data were collected.

RESULTS

A total of 14 pediatric patients were diagnosed with SR-GVHD after allo-HSCT and received ruxolitinib. The age of the patients ranged from 3 months to 12 years old. The dosage of ruxolitinib ranged from 2.5 mg twice daily to 7.5 mg twice daily, mainly according to patient weight. The total overall response rate (ORR) was 64.3% (9/14), with 63.6% (7/11) in aGVHD and 67% (2/3) in cGVHD. Of the 14 patients, adverse effects were observed in 9 patients (64.3%), including cytopenia, infection, and elevated alanine aminotransferase. In addition, seven reports on the treatment of SR-GVHD in children with ruxolitinib were included for systematic analysis, with the ORR ranging from 45 to 87% in aGVHD and 70-91% in cGVHD.

CONCLUSION

Given its effectiveness and safety, ruxolitinib could be used to treat SR-GVHD in children after HSCT.

Progress on the Pharmacological Targeting of Janus Pseudokinases

The Janus kinases (JAKs) are key components of the JAK-STAT signaling pathway and are involved in myriad physiological processes. Though they are the molecular targets of many FDA-approved drugs, these drugs manifest adverse effects due in part to their inhibition of the requisite JAK kinase activity. However, the JAKs uniquely possess an integrated pseudokinase domain (JH2) that regulates the adjacent kinase domain (JH1). The therapeutic targeting of JH2 domains has been less thoroughly explored and may present an avenue to modulate the JAKs without the adverse effects associated with targeting the adjacent JH1 domain. The potential of this strategy was recently demonstrated with the FDA approval of the TYK2 JH2 ligand deucravacitinib for treating plaque psoriasis. In this light, the structure and targetability of the JAK pseudokinases are discussed, in conjunction with the state of development of ligands that bind to these domains.

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.

Efficacy and safety of human umbilical cord-derived mesenchymal stem cells (hUC-MSC PLEB001) for the treatment of grade II-IV steroid-refractory acute graft-versus-host disease: a study protocol for a multicenter, randomized, double-blind, placebo-controlled, phase II trial

BACKGROUND

Systemic corticosteroid therapy failure is quite common in patients with newly diagnosed acute graft-versus-host disease (aGVHD). Growing evidence has suggested that mesenchymal stem cell (MSC) therapy could be a promising treatment option for aGVHD due to its distinctive immunomodulating functions. However, there is a lack of randomized well-controlled clinical trials.

METHODS

This is a clinical trial protocol for a multicenter, randomized, double-blind, placebo-controlled phase II study. The aim of the trial is to evaluate the efficacy and safety of the administration of the human umbilical cord-derived MSC product hUC-MSC PLEB001 in patients with grade II-IV, steroid-refractory aGVHD. A total of 96 patients will be randomized 1:1 to receive MSC or placebo treatment twice per week for 4 weeks, in addition to second-line therapy according to institutional standards. Patients who achieve partial response (PR) at day 28 will be eligible to receive further infusions twice per week for an additional 4 weeks.

DISCUSSION

This study will evaluate the efficacy and safety of MSC therapy in patients who have failed first-line steroid treatment for grade II-IV aGVHD.

TRIAL REGISTRATION

Chinese Clinical Trial Registry (ChiCTR), ChiCTR2000035740. Registered on 16 August 2020.

Pharmacokinetics and Pharmacodynamics of Ruxolitinib: A Review

BACKGROUND AND OBJECTIVE

Ruxolitinib is a tyrosine kinase inhibitor targeting the Janus kinase (JAK) and signal transducer and activator of transcription (STAT) pathways. Ruxolitinib is used to treat myelofibrosis, polycythemia vera and steroid-refractory graft-versus-host disease in the setting of allogeneic stem-cell transplantation. This review describes the pharmacokinetics and pharmacodynamics of ruxolitinib.

METHODS

Pubmed, EMBASE, Cochrane Library and web of Science were searched from the time of database inception to march 15, 2021 and was repeated on November 16, 2021. Articles not written in English, animal or in vitro studies, letters to the editor, case reports, where ruxolitinib was not used for hematological diseases or not available as full text were excluded.

RESULTS

Ruxolitinib is well absorbed, has 95% bio-availability, and is bound to albumin for 97%. Ruxolitinib pharmacokinetics can be described with a two-compartment model and linear elimination. Volume of distribution differs between men and women, likely related to bodyweight differences. Metabolism is mainly hepatic via CYP3A4 and can be altered by CYP3A4 inducers and inhibitors. The major metabolites of ruxolitinib are pharmacologically active. The main route of elimination of ruxolitinib metabolites is renal. Liver and renal dysfunction affect some of the pharmacokinetic variables and require dose reductions. Model-informed precision dosing might be a way to further optimize and individualize ruxolitinib treatment, but is not yet advised for routine care due to lack of information on target concentrations.

CONCLUSION

Further research is needed to explain the interindividual variability of the ruxolitinib pharmacokinetic variables and to optimize individual treatment.

Utilization of Supervised Machine Learning to Understand Kinase Inhibitor Toxophore Profiles

There have been more than 70 FDA-approved drugs to target the ATP binding site of kinases, mainly in the field of oncology. These compounds are usually developed to target specific kinases, but in practice, most of these drugs are multi-kinase inhibitors that leverage the conserved nature of the ATP pocket across multiple kinases to increase their clinical efficacy. To utilize kinase inhibitors in targeted therapy and outside of oncology, a narrower kinome profile and an understanding of the toxicity profile is imperative. This is essential when considering treating chronic diseases with kinase targets, including neurodegeneration and inflammation. This will require the exploration of inhibitor chemical space and an in-depth understanding of off-target interactions. We have developed an early pipeline toxicity screening platform that uses supervised machine learning (ML) to classify test compounds’ cell stress phenotypes relative to a training set of on-market and withdrawn drugs. Here, we apply it to better understand the toxophores of some literature kinase inhibitor scaffolds, looking specifically at a series of 4-anilinoquinoline and 4-anilinoquinazoline model libraries.

Population pharmacokinetics of ruxolitinib in children with hemophagocytic lymphohistiocytosis: focus on the drug-drug interactions

PURPOSE

The optimal dose regimen of ruxolitinib (RUX) in children with hemophagocytic lymphohistiocytosis (HLH) remains to be determined. The aim was to develop and verify a population pharmacokinetic (PPK) model, and then provide references for the optimization of dose regimen of RUX in children with HLH.

METHODS

A total of 189 RUX concentrations from 32 children were included. The PPK model was established using the nonlinear mixed-effects model approach. Predictive performance and stability of the final PPK model were evaluated. The exposure of RUX in different clinical scenarios was simulated through Monte Carlo simulations.

RESULTS

A one-compartment model with first-order absorption and linear elimination was identified to describe the disposition of RUX. The absorption rate constant (K_a) in the final PPK model was 1.05 h^-1, and the apparent clearance (CL/F) and volume of distribution (V/F) were 9.80 L/h and 30.6 L, respectively. Coadministration with triazoles (TZS) and azithromycin (AZM) resulted in approximately 31.0% and 32.4% reductions in the CL/F of RUX, respectively. Multiple evaluation procedures showed satisfactory predictive performance and stability of the final model. Monte Carlo simulations showed that the exposure of RUX was significantly affected by the coadministration with TZS and/or AZM under different clinical scenarios.

CONCLUSION

For the first time, a PPK model of RUX in children with HLH was developed and evaluated. The coadministration with TZS and/or AZM were found to reduce the clearance of RUX in children. These findings could provide new insights for the precise treatment of RUX in children with HLH.

Ruxolitinib does not completely abrogate the functional capabilities of TLR4/9 ligand-activated NK cells

Introduction

Natural killer (NK) cells are lymphocytes from the innate immune system part of the first defense barrier against infected and transformed cells, representing 5%-15% of peripheral blood lymphocytes. The cytotoxic capacity of NK cells is controlled by a balance between inhibitory and activating NK receptors expressed on their surface, which recognize and interact with the ligands on stressed cells. The cytokines involved in NK cell activation, proliferation, survival, and cytotoxicity are signaled mainly through the Janus kinase and signal transducer and activator of transcription proteins (JAK/STAT) pathway. NK cells are also activated in response to pathogens through Toll-like receptors (TLRs) expressed on their surface. Ruxolitinib is a specific JAK1/2 inhibitor approved for treating myelofibrosis and for steroid-refractory acute and chronic graft-versus-host disease (SR-GvHD).

Methods

Purified NK cells from healthy donors were stimulated with two TOLL-like receptor ligands, LPS and CpG, in the presence of different concentrations of Ruxolitinib.

Results

This study showed the effects of ruxolitinib on TLR4 and TLR9 ligand-activated NK cells from healthy donors. Ruxolitinib did not completely inhibit STAT3 phosphorylation and had a moderate effect on NK cell cytokine activation via the TLR pathway. Only the highest doses of ruxolitinib led to a decrease in the pro-inflammatory cytokines tumor necrosis factor α, interferon-γ, interleukin-6, and interleukin-1β. The cytotoxic capacity of stimulated NK cells versus K562, SEM, and MV-4-11 cell lines was reduced by increasing doses of ruxolitinib, but it was not completely abolished and we observed no major changes in degranulation capacity. Phenotypic changes were observed in activated NK cells in the presence of ruxolitinib. In a small cohort of pediatric patients treated with ruxolitinib for SR-GvHD, we observed no decrease in NK cell counts; however, further prospective studies with larger cohorts are necessary to confirm this finding.

Discussion

In summary, our results showed that the functional capabilities and phenotype of NK cells activated through TLR4/9 agonists were not completely abolished by the inhibition of the JAK-STAT pathway by ruxolitinib.

Top Selling (2026) Small Molecule Orphan Drugs: A Journey into Their Chemistry

This review describes, from a chemical point of view, the top "blockbuster" small molecule orphan drugs according to their forecasted sales in 2026. Orphan drugs are intended for the treatment, prevention, or diagnosis of a rare disease or condition. These molecules are mostly addressed to the treatment of rare forms of cancer. The respiratory and central nervous systems represent other common therapeutic subcategories. This work will show how the orphan drugs market has significantly grown and will account for a consistent part of prescriptions by 2026.

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 in steroid-refractory graft-versus-host disease: A meta-analysis

Ruxolitinib is an important treatment for steroid refractory graft-versus-host disease (SR-GVHD). Therefore, we reported the updated results of a systematic review and meta-analysis of ruxolitinib as treatment for SR-GVHD. In addition, we wanted to compare the efficacy and safety between children and adults with SR-GVHD. Overall response rate (ORR) after ruxolitinib treatment was chosen as the primary end point. Complete response rate (CRR), infection, myelosuppression, and overall survival (OS) were chosen as secondary end points. A total of 37 studies were included in this meta-analysis, and 1,580 patients were enrolled. ORR at any time after ruxolitinib treatment was 0.77 [95% confidence interval (CI): 0.68–0.84] and 0.78 (95% CI: 0.74–0.81), respectively, for SR-aGVHD and SR-cGVHD. CRR at any time after ruxolitinib treatment was 0.49 (95% CI: 0.40–0.57) and 0.15 (95% CI: 0.10–0.23), respectively, for SR-aGVHD and SR-cGVHD. The ORRs at any time after treatment was highest in mouth SR-cGVHD, followed by skin, gut, joints and fascia, liver, eyes, esophagus, and lung SR-cGVHD. The incidence rate of infections after ruxolitinib treatment was 0.61 (95% CI: 0.45–0.76) and 0.47 (95% CI: 0.31–0.63), respectively, for SR-aGVHD and SR-cGVHD. The incidence rates of overall (grades I–IV) and severe (grades III–IV) cytopenia were 53.2% (95% CI: 16.0%–90.4%) and 31.0% (95% CI: 0.0–100.0%), respectively, for SR-aGVHD, and were 28.8% (95% CI:13.0%–44.6%) and 10.4% (95% CI: 0.0–27.9%), respectively, for SR-cGVHD. The probability rate of OS at 6 months after treatment was 63.9% (95% CI: 52.5%–75.2%) for SR-aGVHD. The probability rates of OS at 6 months, 1 year, and 2 years after treatment were 95% (95% CI: 79.5%–100.0%), 78.7% (95% CI: 67.2%–90.1%), and 75.3% (95% CI: 68.0%–82.7%), respectively, for SR-cGVHD. The ORR, CRR, infection events, and myelosuppression were all comparable between children and adults with SR-GVHD. In summary, this study suggests that ruxolitinib is an effective and safe treatment for SR-GVHD, and both children and adults with SR-GVHD could benefit from ruxolitinib treatment.

Disease progression, treatments, hospitalization, and clinical outcomes in acute GVHD: a multicenter chart review

Acute graft-versus-host disease (GVHD) remains a barrier to successful allogeneic hematopoietic cell transplantation (HCT) outcomes. This multicenter, retrospective chart review describes disease progression, treatment patterns, hospitalizations, and clinical outcomes among 475 patients (≥12 years old) who developed grades II–IV acute GVHD after their first HCT (January 2014–June 2016). Median (interquartile range) age at HCT was 55 (44–63) years. From the date of acute GVHD diagnosis, 190 patients (40.0%) experienced progression to more severe disease and/or developed new organ involvement. Among 431 patients with grades II–IV acute GVHD at diagnosis, 73.1% received first-line systemic corticosteroids. During follow-up (median 524 days since acute GVHD diagnosis), 23.4% of patients had an increase in steroid dose and 44.4% were unable to taper below 10 mg/day. Over half of patients (54.9%) required ≥1 hospital readmission within 100 days post-HCT (≥2 readmissions in 22.3%); mean inpatient length of stay upon readmission was 27.5 days. Approximately half of patients (52.8%) died during follow-up; 1-year overall mortality from date of acute GVHD diagnosis and nonrelapse mortality rates were 35.2% and 25.5%, respectively. Overall, patients who developed acute GVHD following HCT had poor clinical outcomes, highlighting the unmet need for early and effective treatment strategies.

Impact of JAK Inhibitors in Pediatric Patients with STAT1 Gain of Function (GOF) Mutations-10 Children and Review of the Literature

INTRODUCTION

Since the first description of gain of function (GOF) mutations in signal transducer and activator of transcription (STAT) 1, more than 300 patients have been described with a broad clinical phenotype including infections and severe immune dysregulation. Whilst Jak inhibitors (JAKinibs) have demonstrated benefits in several reported cases, their indications, dosing, and monitoring remain to be established.

METHODS

A retrospective, multicenter study recruiting pediatric patients with STAT1 GOF under JAKinib treatment was performed and, when applicable, compared with the available reports from the literature.

RESULTS

Ten children (median age 8.5 years (3-18), receiving JAKinibs (ruxolitinib (n = 9) and baricitinib (n = 1)) with a median follow-up of 18 months (2-42) from 6 inborn errors of immunity (IEI) reference centers were included. Clinical profile and JAKinib indications in our series were similar to the previously published 14 pediatric patients. 9/10 (our cohort) and 14/14 patients (previous reports) showed partial or complete responses. The median immune deficiency and dysregulation activity scores were 15.99 (5.2-40) pre and 7.55 (3-14.1) under therapy (p = 0.0078). Infection, considered a likely adverse event of JAKinib therapy, was observed in 1/10 patients; JAKinibs were stopped in 3/10 children, due to hepatotoxicity, pre-HSCT, and absence of response.

CONCLUSIONS

Our study supports the potentially beneficial use of JAKinibs in patients with STAT1 GOF, in line with previously published data. However, consensus regarding their indications and timing, dosing, treatment duration, and monitoring, as well as defining biomarkers to monitor clinical and immunological responses, remains to be determined, in form of international prospective multicenter studies using established IEI registries.

Disease progression, hospital readmissions, and clinical outcomes for patients with steroid-refractory acute graft-versus-host disease: A multicenter, retrospective study

Acute graft-versus-host disease (GVHD) is a significant cause of morbidity and mortality following allogeneic hematopoietic cell transplantation (HCT). This analysis of 168 patients (mean age, 54.8 years) from a multicenter, retrospective chart review describes the clinical course, treatment patterns, hospitalizations, and clinical outcomes of patients aged ≥12 years who developed grades II–IV acute GVHD after their first allogeneic HCT (January 1, 2014, to June 30, 2016) and were refractory to or dependent on corticosteroids. Between diagnosis and maximum grade (median, 6.0 days), 53.6% of patients had new organ involvement, particularly lower gastrointestinal tract acute GVHD, or an increase in acute GVHD grade. Eighty-nine patients (53.0%) received additional systemic GVHD therapy (after systemic corticosteroids) within a median of 21.0 days. Hospital readmission(s) was required for 56.5% of patients within 100 days post-HCT (mean inpatient length of readmission stay, 49.5 days); 24.4% had ≥2 readmissions within 100 days post-HCT. From the date of acute GVHD diagnosis, 70.2% of patients died at a median (interquartile range) of 117.5 (49–258) days. In summary, steroid-refractory and steroid-dependent acute GVHD is associated with a rapidly worsening clinical course that leads to high readmission and mortality rates, emphasizing the need for effective and tolerable therapies.

Prediction of outcomes after second-line treatment for acute graft-versus-host disease

Acute graft-versus-host disease (GVHD) requiring second-line treatment represents a highly morbid complication of allogenic hematopoietic cell transplantation (HCT). Recent studies have defined short-term outcomes after second-line treatment for acute GVHD, but longer-term outcomes have not been well defined. We examined overall survival (OS) and failure-free-survival (FFS) of 216 patient who had HCT who received second-line treatment for acute GVHD. Failure time for FFS was defined as the earliest of death, relapse, or implementation of third-line treatment. Multivariable Cox regression was used to identify risk factors for mortality and failure, and predictive models were derived for 6- and 12-month mortality. Point estimates of OS at 6 and 12 months were 59% (95% confidence interval [CI], 52-65) and 52% (95% CI, 45-68), respectively. Point estimates of FFS at 6 and 12 months were 42% (95% CI, 35-48) and 37% (95% CI, 31-43), respectively. Predictive models for both end points included serum albumin and total bilirubin concentrations at the onset of second-line treatment, patient age at onset of second-line therapy, and a combination of abdominal pain/stage 4 gut involvement. Optimism-corrected areas under the receiver-operator characteristic curve and Brier scores were 77.4 and 0.169 for 6-month mortality, respectively, and 80.0 and 0.169 for 12-month mortality. We identify risk factors associated with mortality and failure after second-line treatment of acute GVHD, provide historical benchmarks for assessment of FFS and OS in other studies, and propose predictive models for 6- and 12-month mortality that could be used to generate population-specific benchmarks.

FDA Approval Summary: Ruxolitinib for Treatment of Chronic Graft-Versus-Host Disease after Failure of One or Two Lines of Systemic Therapy

On September 22, 2021, the Food and Drug Administration approved ruxolitinib for the treatment of chronic graft-versus-host disease (cGVHD) after the failure of one or two lines of systemic therapy in adult and pediatric patients 12 years and older. Approval was based on Study INCB 18424-365 (REACH-3; CINC424D2301; NCT03112603), a randomized, open-label, multicenter trial of ruxolitinib in comparison to best available therapy (BAT) for the treatment of corticosteroid-refractory cGVHD occurring after the allogeneic hematopoietic stem cell transplantation. A total of 329 patients were randomized 1:1 to receive either ruxolitinib 10 mg twice daily (n = 165) or BAT (n = 164). BAT was selected by the investigator prior to randomization. The overall response rate through Cycle 7 Day 1 was 70% (95% CI, 63-77) in the ruxolitinib arm, and 57% (95% CI, 49-65) in the BAT arm. The median duration of response, calculated from first response to progression, death, or initiation of new systemic therapies for cGVHD, was 4.2 months (95% CI, 3.2-6.7) for the ruxolitinib arm and 2.1 months (95% CI, 1.6-3.2) for the BAT arm; and the median time from first response to death or initiation of new systemic therapies for cGVHD was 25 months (95% CI, 16.8-not estimable) for the ruxolitinib arm and 5.6 months (95% CI, 4.1-7.8) for the BAT arm. Common adverse reactions included anemia, thrombocytopenia, and infections. Given the observed response rate with durability, the clinical benefit of ruxolitinib appears to outweigh the risks of treatment for cGVHD after the failure of one or two lines of systemic therapy.

Ruxolitinib-corticosteroid as first-line therapy for newly diagnosed high-risk acute graft versus host disease: study protocol for a multicenter, randomized, phase II controlled trial

BACKGROUND

The response rate of the first-line therapy with corticosteroid for acute graft versus host disease (aGVHD) is about 50%, and steroid-refractory disease is associated with high mortality. The improved response rate to the first-line therapy of newly diagnosed aGVHD patients would result in therapeutic benefits. Ruxolitinib, a selective Janus kinase (JAK) 1/2 inhibitor, has been approved for the treatment of steroid-refractory acute GVHD. The addition of ruxolitinib to the first-line therapy may improve the efficacy of corticosteroids.

METHODS

This investigator-initiated, open-label, multicenter, prospective randomized, and controlled two-arm phase II study compares the efficacy and safety of ruxolitinib combined with 1 mg/kg methylprednisolone versus 2 mg/kg methylprednisolone alone in newly diagnosed aGVHD patients. Patients with intermediate or high-risk aGVHD, as defined by the Minnesota aGVHD high-risk score and biomarker algorithm, are eligible for this study. A total of 198 patients will be randomized at a 1:1 ratio and assigned a GVHD risk (intermediate versus high risk) and disease status before transplantation (complete remission versus no complete remission). The primary endpoint is the overall response rate on day 28, which is defined as an improvement of at least one stage in the severity of aGVHD in one organ without deterioration in any other organ or disappearance of any GVHD signs from all organs without requiring new systemic immunosuppressive treatment. The secondary objectives consist of response time, response duration, overall survival, disease-free survival, non-relapse mortality, failure-free survival, and changes in serum levels of proinflammatory cytokines and GVHD-related biomarkers.

DISCUSSION

This open-label, multicenter, two-arm randomized trial will evaluate whether the addition of ruxolitinib combined with corticosteroid is superior to corticosteroid alone in newly diagnosed high-risk aGVHD.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04061876 (version number: 2019.5.18). Registered on July 16, 2019.

Physicochemical Stability Study of Oral Suspension Containing Ruxolitinib in Children with Steroid-Refractory Acute Graft-Versus-Host Disease

Ruxolitinib, used in children with steroid-refractory acute graft-versus-host (GVH) disease, is currently commercially available only as a tablet adult dosage. For the paediatric population, an oral liquid would be an adapted dosage formulation. The aim of this study was to develop ruxolitinib compounded oral suspensions at 2 mg/mL by using commercial tablets in available aqueous vehicle (Inorpha) and to measure its stability at both room temperature and under refrigeration. Chemical stability of suspensions containing ruxolitinib was evaluated for 60 days based on pH, degradation, and drug content. Physical stability of the drug suspension was evaluated by visual aspect and odour. The remaining ruxolitinib concentration of the suspension was at least 95% of the initial concentration after 60 days at both temperatures. The pH, colour, and odour of the suspensions throughout the study remained unchanged with respect to the initial time point.

A Comprehensive Overview of Globally Approved JAK Inhibitors

Janus kinase (JAK) is a family of cytoplasmic non-receptor tyrosine kinases that includes four members, namely JAK1, JAK2, JAK3, and TYK2. The JAKs transduce cytokine signaling through the JAK-STAT pathway, which regulates the transcription of several genes involved in inflammatory, immune, and cancer conditions. Targeting the JAK family kinases with small-molecule inhibitors has proved to be effective in the treatment of different types of diseases. In the current review, eleven of the JAK inhibitors that received approval for clinical use have been discussed. These drugs are abrocitinib, baricitinib, delgocitinib, fedratinib, filgotinib, oclacitinib, pacritinib, peficitinib, ruxolitinib, tofacitinib, and upadacitinib. The aim of the current review was to provide an integrated overview of the chemical and pharmacological data of the globally approved JAK inhibitors. The synthetic routes of the eleven drugs were described. In addition, their inhibitory activities against different kinases and their pharmacological uses have also been explained. Moreover, their crystal structures with different kinases were summarized, with a primary focus on their binding modes and interactions. The proposed metabolic pathways and metabolites of these drugs were also illustrated. To sum up, the data in the current review could help in the design of new JAK inhibitors with potential therapeutic benefits in inflammatory and autoimmune diseases.

Targeting Janus Kinase (JAK) for Fighting Diseases: The Research of JAK Inhibitor Drugs

Janus Kinase (JAK), a nonreceptor protein tyrosine kinase, has emerged as an excellent target through research and development since its discovery in the 1990s. As novel small-molecule targeted drugs, JAK inhibitor drugs have been successfully used in the treatment of rheumatoid arthritis (RA), myofibrosis (MF) and ulcerative colitis (UC). With the gradual development of JAK targets in the market, JAK inhibitors have also received very considerable feedback in the treatment of autoimmune diseases such as atopic dermatitis (AD), Crohn's disease (CD) and graft-versus host disease (GVHD). This article reviews the research progress of JAK inhibitor drugs: introducing the existing JAK inhibitors on the market and some JAK inhibitors in clinical trials currently. In addition, the synthesis of various types of JAK inhibitors were summarized, and the effects of different drug structures on drug inhibition and selectivity.

Co-Administration with Voriconazole Doubles the Exposure of Ruxolitinib in Patients with Hematological Malignancies

Background

Ruxolitinib is newly approved for glucocorticoid-refractory acute graft-versus-host disease (GVHD) in patients undergoing allo-geneic hematopoietic stem-cell transplantation (allo-HSCT), and voriconazole is commonly used in allo-HSCT recipients for the prophylaxis or treatment of invasive fungal infections (IFIs). Drug–drug interaction (DDI) may occur between them because their metabolic pathways overlap and can be inhibited by voriconazole, including cytochrome P450 (CYP) isozymes 3A4 and 2C9.

Objective

In the present study, we aimed to investigate the DDI between ruxolitinib and voriconazole in patients with hematological malignancies.

Methods

A total of 12 patients with hematologic malignancies were enrolled in this single-arm, single-center, Phase I/II, fixed sequence self-control study. All subjects received 5 mg ruxolitinib alone, followed by the co-administration of ruxolitinib and voriconazole. The plasma concentrations of the two drugs were determined by two well-validated high-performance liquid chromatography-tandem mass spectrometry methods. Phoenix WinNonlin software was used to compare the differences in maximum plasma concentration (C_max), time to C_max (T_max), terminal elimination half-life (T_1/2), and apparent plasma clearance (CL/F), as well as area under the curve from time zero to last (AUC_last) and AUC from time zero to infinity (AUC_inf) between the two periods.

Results

After pre-treatment with voriconazole, no significant change existed in T_max, while C_max, T_1/2, AUC_last, and AUC_inf of ruxolitinib were significantly increased by 50.4%, 81.3%, 110.1%, and 118.3%, respectively, and CL/F was significantly decreased to 43.6% compared with patients receiving ruxolitinib alone.

Conclusion

Our findings confirmed a moderate inhibitory DDI between ruxolitinib and voriconazole as voriconazole decreased the elimination and increased the exposure of ruxolitinib in patients with hematologic malignancies. We recommended a dose reduction regimen when voriconazole and ruxolitinib were coadministered. Drug monitoring might help determine the ruxolitinib treatment concentration for aGVHD patients, improve efficacy, and reduce toxicity.

A Prospective, Multicenter Study of Closed System Extracorporeal Photopheresis for Children With Steroid-Refractory Acute Graft-Versus-Host Disease

BACKGROUND

Steroid-refractory (SR) acute graft-versus-host disease (aGvHD) therapy involves intensive immunosuppression, which is associated with significant infectious risk. Extracorporeal photopheresis (ECP) is used to treat SR-aGvHD and is considered to be more immunomodulatory than immunosuppressive. However, pediatric data are mostly retrospective and often involve multi-step ECP that includes apheresis followed by separate photosensitizing/reinfusion on another device.

OBJECTIVE

To prospectively evaluate the efficacy and safety of a single-device ECP system in children with SR-aGvHD.

STUDY DESIGN

Open-label, multicenter, phase 3 study of the THERAKOS® CELLEX® Photopheresis System in children/young adults aged 1 to 21 years with SR-aGvHD. Patients were treated 3 times per week for 4 weeks, then twice weekly through week 12 while maintaining standard aGvHD prophylaxis. The primary efficacy endpoint was the proportion of patients achieving overall response (OR) at day 28 without the addition of next-line systemic treatment. Secondary endpoints included the proportion of patients achieving OR at weeks 8 and 12; the mean weekly steroid dose at weeks 4, 8, and 12; and treatment-emergent adverse events (TEAEs).

RESULTS

Twenty-nine children (median age, 8 years) were enrolled. OR was 55% by day 28, 74% by week 8, and 79% by week 12. Progressive improvements were observed in the skin and the gastrointestinal tract. Mean steroid dose decreased from 1.54 mg/kg/day at baseline to 0.90 mg/kg/day at week 4; 35% of patients achieved >50% steroid dose reduction at week 4 and 75% achieved >50% steroid dose reduction at week 12. Of 168 TEAEs reported among 25 patients (86%), 28 (17%) events were infections and 14 (8%) events were considered to be probably treatment related (all nonserious). Of 627 ECP treatments administered in children/young adults, 68% required blood priming. Treatment-related AEs, including hypotension, hypocalcemia, central line infection, and catheter-site bruising, were rare (1 event each). Three deaths occurred and were deemed unrelated to ECP by the investigators.

CONCLUSION

Use of the THERAKOS® CELLEX® Photopheresis System was effective in children with SR-aGvHD, with more than half experiencing improvement by day 28 and further responses observed over 12 weeks. Very few TEAEs were attributable to ECP, and no new safety signals were observed.

Successful treatment with HLA-matched peripheral hematopoietic stem cell transplantation for very severe hepatitis-associated aplastic anemia complicated with multidrug-resistant bacterial and fungal infections: A case report

Hepatitis-associated aplastic anemia (HAAA) is a life-threatening hematologic disorder characterized by bone marrow failure. Allogeneic hematopoietic stem cell transplantation (HSCT) is the first-line treatment for HAAA. Severe infection and complications in patients with very severe aplastic anemia are the challenges to the efficacy of HSCT. We report a rare case of successful transplantation with HLA-matched peripheral hematopoietic stem cells for a 15-year-old girl suffering from HAAA with multidrug-resistant bacterial and fungal infections. Through effectively controlling infection and optimal timing of transplantation by adjusting the conditioning regimen, the allo-HSCT was successfully performed for the patient. Updated data of following-up 26 months after transplantation showed that the patient was still in complete remission with a good quality of life. This case provided a reference for treating severely infected patients with HAAA before HSCT.

The JAK inhibitor ruxolitinib abrogates immune hepatitis instigated by concanavalin A in mice

Therapeutics that impair the innate immune responses of the liver during the inflammatory cytokine storm like that occurring in COVID-19 are greatly needed. Much interest is currently directed toward Janus kinase (JAK) inhibitors as potential candidates to mitigate this life-threatening complication. Accordingly, this study investigated the influence of the novel JAK inhibitor ruxolitinib (RXB) on concanavalin A (Con A)-induced hepatitis and systemic hyperinflammation in mice to simulate the context occurring in COVID-19 patients. Mice were orally treated with RXB (75 and 150 mg/kg) 2 h prior to the intravenous administration of Con A (20 mg/kg) for a period of 12 h. The results showed that RXB pretreatments were efficient in abrogating Con A-instigated hepatocellular injury (ALT, AST, LDH), necrosis (histopathology), apoptosis (cleaved caspase-3) and nuclear proliferation due to damage (PCNA). The protective mechanism of RXB were attributed to i) prevention of Con A-enhanced hepatic production and systemic release of the proinflammatory cytokines TNF-α, IFN-γ and IL-17A, which coincided with decreasing infiltration of immune cells (monocytes, neutrophils), ii) reducing Con A-induced hepatic overexpression of IL-1β and CD98 alongside NF-κB activation, and iii) lessening Con A-induced consumption of GSH and GSH peroxidase and generation of oxidative stress products (MDA, 4-HNE, NOx) in the liver. In summary, JAK inhibition by RXB led to eminent protection of the liver against Con A-deleterious manifestations primarily via curbing the inflammatory cytokine storm driven by TNF-α, IFN-γ and IL-17A.

Acute GVHD: think before you treat

The treatment of acute graft-versus-host disease (aGVHD) has become more nuanced in recent years with the development of improved risk classification systems and a better understanding of its complex, multisystem pathophysiology. We review contemporary approaches to the risk stratification and initial treatment of aGVHD, including ongoing clinical trials. We summarize the findings that led to the first US Food and Drug Administration approval for steroid-refractory aGVHD (SR-aGVHD), ruxolitinib, as well as some of the challenges clinicians still face in treating SR-aGVHD. Finally, we discuss the evaluation and management of steroid-dependent aGVHD, which affects approximately one-third of patients who have long-term, waxing and waning symptoms distinct from chronic GVHD. Future clinical trials for aGVHD treatment may identify steroid-sparing approaches for patients who have a high likelihood of response and approaches to improve tissue repair and dysbiosis for those unlikely to respond to immunosuppression alone.

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.

Azacitidine for the treatment of steroid-refractory chronic graft-versus-host disease: the results of the phase II AZTEC clinical trial

Chronic graft-versus-host disease (cGvHD) is a major cause of non-relapse morbidity and mortality following allogeneic stem cell transplant. Over half of patients with moderate or severe cGvHD fail to respond adequately to first-line treatment with systemic steroids, and although a range of second-line options have been employed, a lack of prospective evidence means there is no standard of care. The AZTEC trial is a prospective, single-arm, phase II study investigating the safety and activity of azacitidine for the treatment of cGvHD in patients who are resistant to, or intolerant of, systemic steroid therapy. The co-primary outcomes were treatment tolerability, and activity measured as objective response according to modified National Institutes of Health criteria. Fourteen patients were recruited to the first stage of the trial, of whom seven completed the planned six cycles of azacitidine 36 mg/m2 days 1-5 per 28-day cycle. Azacitidine was tolerated by 13/14 patients, and 7/14 showed an objective response. Clinical responses were mirrored by improvements in patient-reported cGvHD symptoms and quality of life. AZTEC demonstrates that azacitidine is a safe and promising option for the treatment of cGvHD, and continued evaluation in the second stage of this phase II efficacy study is supported.

Elevated REG3α predicts refractory aGVHD in patients who received steroids-ruxolitinib as first-line therapy

We started a single-arm, phase II, open-label, prospective clinical trial using steroids-ruxolitinib as the first-line therapy for intermediate- to high-risk aGVHD (NCT04397367). Here, we report the association of a biomarker panel (sST2, REG3α, sTNFR1, IL-6 and IL-8) with responses to GVHD therapy. The novel first-line therapy for 39 patients with newly diagnosed aGVHD consisted of 1 mg/kg methylprednisolone and 5 mg/day ruxolitinib. The serum concentrations of the biomarkers were prospectively detected at planned time points. Of the 39 patients, the complete response rate at day 28 was 82.05%. In patients who achieved CR, the concentrations of REG3α (P₁₄ = 0.01; P₂₈ = 0.10) and sTNFR1 (P₁₄ = 0.42; P₂₈ = 0.04) declined at day 14 and day 28 compared with the pre-enrolment levels. In refractory patients, the levels of REG3α at day 14 were higher than those pre-enrolment (P = 0.04). REG3α (P = 0.02) was elevated in the refractory patients compared with the patients achieving CR at day 14 after enrolment, while there was no significant difference in the levels of sST2, sTNFR1 or IL-6. Elevated REG3α levels may predict refractory aGVHD after novel first-line therapy with steroids-ruxolitinib.

The role of biomarkers in risk stratification, treatment and outcome in acute GVHD

PURPOSE OF REVIEW

Graft-versus-host disease (GVHD) following hematopoietic cell transplant (HCT) has a significant impact on morbidity and mortality among recipients. Predicting the long-term outcomes at the time of diagnosis of GVHD or even after response to up-front therapy can be challenging and only has modest accuracy. With biomarkers available to help guide decision-making, the landscape of GVHD is evolving.

RECENT FINDINGS

Several acute GVHD biomarkers have been identified, with some better able to categorize patients based on their GVHD severity and potential for refractory disease than standard clinical staging or response criteria.

SUMMARY

Biomarkers are now being incorporated into the clinical trial design for both high and low-risk GVHD. These findings will likely impact how clinical care is delivered in the future as improved risk stratification has the potential to improve outcomes by providing individualized treatment plans for affected patients.

Off-the-shelf bone marrow-derived mesenchymal stem cell treatment for acute graft-versus-host disease: real-world evidence

Temcell is a cryopreserved, human bone marrow-derived mesenchymal stem cell (MSC) product approved for the treatment of patients of all ages with acute graft-versus-host disease (GVHD). Initial experience with Temcell in a real-world setting from a cellular therapy registry in Japan is presented. A total of 381 consecutive patients were enrolled since its approval in 2016. The median cell number infused was 2.00 × 106/kg. The most common number of infusions was 8 in 100 patients. Of the 306 evaluable patients, the overall response rate (ORR) on day 28 after the start of MSC therapy was 56%. Of the 151 evaluable patients who received it as second-line therapy following first-line steroid therapy for classic acute GVHD, the ORR was 61%. Liver involvement of GVHD and ≥14 days from first-line steroid therapy to second-line MSC therapy was associated with a lower ORR. Day 28 ORR, patient age, GVHD grade, GVHD organ involvement, and a number of GVHD therapies before MSC therapy were associated with nonrelapse mortality. Overall survival at 6 months in 381 patients was 40%. This study suggests that Temcell is one of the treatment options for steroid-refractory acute GVHD until a new treatment with survival benefit is developed.

Venetoclax or Ruxolitinib in Pre-Transplant Conditioning Lowers the Engraftment Barrier by Different Mechanisms in Allogeneic Stem Cell Transplant Recipients

Allogeneic stem cell transplantation (alloSCT) is utilised to cure haematological malignancies through a combination of conditioning regimen intensity and immunological disease control via the graft versus tumour (GVT) effect. Currently, conventional myeloablative chemotherapeutic or chemoradiation conditioning regimens are associated with significant side effects including graft versus host disease (GVHD), infection, and organ toxicity. Conversely, more tolerable reduced intensity conditioning (RIC) regimens are associated with unacceptably higher rates of disease relapse, partly through an excess incidence of mixed chimerism. Improvement in post-alloSCT outcomes therefore depends on promotion of the GVT effect whilst simultaneously reducing conditioning-related toxicity. We have previously shown that this could be achieved through BCL-2 inhibition, and in this study, we explored the modulation of JAK1/2 as a strategy to lower the barrier to donor engraftment in the setting of RIC. We investigated the impact of short-term treatment of BCL2 (venetoclax) or JAK1/2 (ruxolitinib) inhibition on recipient natural killer and T cell immunity and the subsequent effect on donor engraftment. We identified striking differences in mechanism of action of these two drugs on immune cell subsets in the bone marrow of recipients, and in the regulation of MHC class-II and interferon-inducible gene expression, leading to different rates of GVHD. This study demonstrates that the repurposed use of ruxolitinib or venetoclax can be utilised as pre-transplant immune-modulators to promote the efficacy of alloSCT, whilst reducing its toxicity.

Effective treatment of late-onset noninfectious pulmonary complication with ruxolitinib in an 8-year-old boy

Haematopoietic stem cell transplantation (HSCT) is an effective treatment for many malignant and nonmalignant diseases both in adults and children, but this procedure can be burdened by the so-called “late-onset non-infectious pulmonary complications” (LONIPCs), which are characterised by significant morbidity and mortality [1]. LONIPCs include different forms of inflammatory lung involvement, occurring after 100 days and within 2–3 years following HSCT [2].

Ruxolitinib could be considered as an option in the treatment of LONIPCs in children when other treatments are ineffective. Spirometry is a valuable tool for both diagnosis and follow-up of LONIPCs in children.https://bit.ly/3BmOYfb

New therapeutic targets and biomarkers for acute graft-versus-host disease (GVHD)

INTRODUCTION

Acute Graft-versus-Host Disease (GVHD) is the major toxicity of allogeneic hematopoietic cell transplantation (HCT). Systemic steroids are the standard primary treatment but only half of the patients will respond completely and the survival of steroid-refractory patients is poor. The gastrointestinal (GI) tract is a key target organ that usually determines a patient's response to therapy.

AREAS COVERED

This review summarizes the use of clinical grading systems and biomarkers in GVHD treatment and highlights pathophysiologic phases of acute GVHD as context for the mechanisms of action and therapeutic targets of various approaches. We reviewed >100 publications and performed a search of ongoing, current clinical trials on the emerging therapeutic targets for prophylaxis and treatment of acute GVHD. Search databases included clinicaltrials.gov and PUBMED. Search terms and keywords included 'acute graft-versus-host disease,' 'GVHD,' 'graft versus host,' 'treatment.'

EXPERT OPINION

Future strategies will employ a risk-adapted therapy using biomarkers, which more accurately predict 6-month NRM. Strategies for high-risk patients will inhibit GI tract damage by selective targeting of effectors (e.g. inhibition of JAK signaling in T cells), blockade of trafficking through mAbs against integrin receptors, or enhancement of target cell survival. Future strategieswill reduce immunosuppression to avoid risk of infections and relapse.

A short course of tofacitinib sustains the immunoregulatory effect of CTLA4-Ig in the presence of inflammatory cytokines and promotes long-term survival of murine cardiac allografts

Costimulation blockade-based regimens are a promising strategy for management of transplant recipients. However, maintenance immunosuppression via CTLA4-Ig monotherapy is characterized by high frequency of rejection episodes. Recent evidence suggests that inflammatory cytokines contribute to alloreactive T cell activation in a CD28-independent manner, a reasonable contributor to the limited efficacy of CTLA4-Ig. In this study, we investigated the possible synergism of a combined short-term inhibition of cytokine signaling and CD28 engagement on the modulation of rejection. Our results demonstrate that the JAK/STAT inhibitor tofacitinib restored the immunomodulatory effect of CTLA4-Ig on mouse alloreactive T cells in the presence of inflammatory cytokines. Tofacitinib exposure conferred dendritic cells with a tolerogenic phenotype reducing their cytokine secretion and costimulatory molecules expression. JAK inhibition also directly affected T cell activation. In vivo, the combination of CTLA4-Ig and tofacitinib induced long-term survival of heart allografts and, importantly, it was equally effective when using grafts subjected to prolonged ischemia. Transplant survival correlated with a reduction in effector T cells and intragraft accumulation of regulatory T cells. Collectively, our studies demonstrate a powerful synergism between CTLA4-Ig and tofacitinib and suggest their combined use is a promising strategy for improved management of transplanted patients.