Comparison of the efficacy and safety of tofacitinib and filgotinib in patients with active rheumatoid arthritis: a Bayesian network meta-analysis of randomized controlled trials

Comparison of drug retention of TNF inhibitors, other biologics and JAK inhibitors in RA patients who discontinued JAK inhibitor therapy

OBJECTIVES

JAK Inhibitors (JAKi) are recommended DMARDs for patients with moderate-to-severe RA who failed first-line therapy with methotrexate. There is a lack of data allowing an evidence-based choice of subsequent DMARD therapy for patients who had discontinued JAKi treatment. We aimed to compare the effectiveness of TNF inhibitor (TNFi) therapy vs JAKi vs other mode of action (OMA) biologic DMARD (bDMARD) in RA patients who were previously treated with a JAKi.

METHODS

RA patients who discontinued JAKi treatment within the Swiss RA registry SCQM were included for this observational prospective cohort study. The primary outcome was drug retention for either TNFi, OMA bDMARD or JAKi. The hazard ratio for treatment discontinuation was calculated adjusting for potential confounders. A descriptive analysis of the reasons for discontinuation was performed.

RESULTS

Four hundred treatment courses of JAKi were included, with a subsequent switch to either JAKi, TNFi or OMA bDMARD. The crude overall drug retention was higher in patients switching to another JAKi as compared with TNFi and comparable to OMA. A significant difference of JAKi vs TNFi persisted after adjusting for potential confounders.

CONCLUSION

In a real-world population of RA patients who discontinued treatment with a JAKi, switching to another JAKi resulted in a higher drug retention than switching to a TNFi. A switch to a second JAKi seems an effective therapeutic option.

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.

Filgotinib, a novel JAK1-preferential inhibitor for the treatment of rheumatoid arthritis: An overview from clinical trials

In the treatment of rheumatoid arthritis (RA), Janus kinase inhibitors (jakinibs) represent an emerging class of targeted therapies in addition to biologics. The number of jakinibs has been growing and as of 2020, filgotinib was the latest jakinib to enter the international market for treating RA. Filgotinib has demonstrated preferential inhibition of JAK1-dependent cytokine signaling in in vitro assays. It has been evaluated in the DARWIN (phase 2) and FINCH (phase 3) series of clinical studies for treating patients with moderately-to-severely active RA. Filgotinib received regulatory approval in Japan and Europe in September 2020, while in August 2020 the United States Food and Drug Administration requested additional data from two ongoing clinical studies assessing the potential impact of filgotinib on sperm parameters. This article will review the pharmacological properties, efficacy, and safety of filgotinib as demonstrated in clinical studies. Expert opinion will be provided on jakinibs for RA treatment from the viewpoints of basic research and clinical practice.

Emerging protein kinase inhibitors for the treatment of rheumatoid arthritis

INTRODUCTION

Protein tyrosine kinase inhibitors are emergent drugs in the treatment of rheumatoid arthritis (RA); they block the signal transduction in immune cells preventing the production and release of pro-inflammatory cytokines.

AREAS COVERED

The current research aims to review the role of Janus, Bruton's and spleen kinase inhibitors for the treatment of RA. Mechanism of action, rationale for usage, and the main efficacy and safety outcomes in phase II and III clinical trials are described.

EXPERT OPINION

In RA, the development of Bruton kinase inhibitors was interrupted because they failed to demonstrate superiority versus placebo. The spleen kinase inhibitors had their development deprioritized because their risk/benefit profile was unfavorable compared to janus kinase inhibitors (JAKi). JAKi proved to be effective in treatment naïve patients and in those with previous failure to methotrexate and/or biological therapy. There still remain important points about JAKi that need more studies: the clinical importance of JAKi selectivity should be further evaluated in head-to-head trials and the safety profile of JAKi, mainly regarding the risk of malignancy and thromboembolic events, must be analyzed in long-term real-life studies.

Filgotinib in Rheumatoid Arthritis: A Profile of Its Use

Filgotinib (Jyseleca^®), an oral Janus kinase (JAK) inhibitor, is approved as monotherapy or in combination with methotrexate to treat moderate to severe active rheumatoid arthritis (RA) in adults who have an inadequate response or intolerance to one or more disease-modifying antirheumatic drugs (DMARDs). In phase 3 trials, once-daily filgotinib was generally well tolerated and associated with an improvement in RA signs and symptoms as well as physical function in patients with an inadequate response to ongoing methotrexate, an inadequate response to ongoing conventional synthetic DMARDs plus an inadequate response or intolerance to prior biologic DMARDs, or limited or no prior exposure to methotrexate. In addition, filgotinib was noninferior to adalimumab in terms of low disease activity response rate (DAS28-CRP ≤ 3.2) in patients with an inadequate response to methotrexate. Filgotinib also appeared to inhibit the radiographic progression of joint damage and led to low disease activity or disease remission (DAS28-CRP < 2.6). Filgotinib showed sustained efficacy, and the safety profile of filgotinib longer term was similar to that in the phase 2 and 3 trials.

Rheumatoid arthritis (RA) is a chronic autoimmune inflammatory disease mainly affecting the small joints of the hands and feet. While there is no cure for RA, biologic disease-modifying antirheumatic drugs (DMARDs), which target the inflammatory cytokines (and their receptors) involved in RA, can achieve low disease activity or disease remission. However, these drugs are not always effective or well tolerated and their administration routes (intravenous or subcutaneous) can be a barrier to use. More recently, oral drugs that act on pathways downstream of cytokine receptors have been developed. These drugs, the Janus kinase (JAK) inhibitors, are targeted synthetic DMARDs. Filgotinib (Jyseleca^®), a second-generation JAK inhibitor, improves joint swelling, disease activity, pain, and physical functioning and reduces progression of joint damage in adults with moderate to severe active RA and is generally well tolerated. Like other JAK inhibitors, filgotinib is recommended in treatment guidelines as an effective alternative to biologic DMARDs in adults with moderate to severe active RA who have not responded adequately to or who do not tolerate other DMARDs.

Preclinical Characterization of the Selective JAK1 Inhibitor LW402 for Treatment of Rheumatoid Arthritis

BACKGROUND

Research on JAK family members as therapeutic targets for autoimmune diseases has brought tofacitinib and baricitinib into clinical for the treatment of rheumatoid arthritis and other autoimmune diseases. Despite the potent efficacy of these first-generation JAK inhibitors, their broad-spectrum JAK inhibition and adverse events warrant development of a JAK1-specific inhibitor to improve their safety profile.

METHODS

In this study, we characterized a JAK1-specific inhibitor, LW402, on biochemical and human whole-blood assays. We further evaluated the therapeutic efficacy of LW402 in a rat adjuvant-induced arthritis (rAIA) model and a mouse collagen-induced arthritis (mCIA) model. The safety of LW402 was evaluated in both SpragueDawley rats and cynomolgus monkeys.

RESULTS

LW402 exhibited potent nanomolar activity against JAK1 and showed a 45-fold selectivity for inhibition of JAK1- over JAK2-dependent signaling induced by either IL6 or GM-CSF in human whole-blood assays. In the rAIA model, oral dosing of LW402 resulted in a dose-dependent improvement in disease symptoms, including reduction in paw swelling, marked reduction in the inflammatory-cell infiltration to synovial tissue, and protection of articular cartilage and bone from damage. The therapeutic efficacy of LW402 correlated well with the plasma exposure of LW402 and the extent of pSTAT3 inhibition in white blood cells. LW402 also effectively eased disease symptoms in the mCIA model. Toxicity studies in the Sprague Dawley rats and cynomolgus monkeys established a ≥5x therapeutic window for LW402 as drug exposures of toxicity study NOAEL dose and pharmacology study ED50 dose were compared.

CONCLUSION

We developed a novel JAK1-specific inhibitor LW402 with potent efficacy in rAIA and mCIA models. We established a good safety profile for LW402 in toxicity studies, and the overall superiority of LW402 should translated well to the clinical setting for the treatment of RA and other autoimmune diseases.

Comparative Efficacy and Safety of Peficitinib Versus Tofacitinib and Baricitinib for Treatment of Rheumatoid Arthritis: A Systematic Review and Network Meta-Analysis

INTRODUCTION

Peficitinib, a Janus kinase (JAK) inhibitor, is approved for clinical use in Japan, Korea, and Taiwan, but head-to-head comparisons versus other JAK inhibitors are lacking. We indirectly compared peficitinib, tofacitinib, and baricitinib for rheumatoid arthritis treatment.

METHODS

We searched MEDLINE, Embase, the Cochrane Central Register of Controlled Trials, ClinicalTrials.gov, and congress archives up until February 12, 2019, for randomized controlled trials of peficitinib, tofacitinib, and baricitinib. Efficacy (American College of Rheumatology responses, disease activity scores, modified total Sharp score, Simplified Disease Activity Index [SDAI]) and safety outcomes were compared using a Bayesian network meta-analysis. The Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) consensus was followed for reporting results. A network meta-regression assessed the impact on outcomes of proportions of patients receiving concomitant methotrexate or of Asian ethnicity.

RESULTS

The network meta-analysis included 21 randomized controlled trials. At 12 weeks, all evaluable efficacy outcomes were comparable or improved with peficitinib 150 mg and 100 mg once daily, versus baricitinib 2 and 4 mg once daily and tofacitinib 5 mg twice daily. At 24 weeks, efficacy outcomes were comparable or improved for each peficitinib dose versus baricitinib and tofacitinib. Risk of adverse events and serious adverse events at 12 weeks were similar with peficitinib 100 and 150 mg versus baricitinib and tofacitinib. The proportion of patients receiving concomitant methotrexate had no effect on any outcome analyzed, but Asian ethnicity had a positive effect on multiple efficacy outcomes.

CONCLUSIONS

Peficitinib had comparable efficacy versus tofacitinib and baricitinib for reduction in disease activity as measured by SDAI, and for reduction in progression of joint damage as measured radiographically. No notable differences in safety outcomes were observed. Further studies are required to better characterize the impact of ethnicity on the efficacy of JAK inhibitors.

JAK Inhibitors and Modulation of B Cell Immune Responses in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic, systemic immune-mediated inflammatory disease that can lead to joint destruction, functional disability and substantial comorbidity due to the involvement of multiple organs and systems. B cells have several important roles in RA pathogenesis, namely through autoantibody production, antigen presentation, T cell activation, cytokine release and ectopic lymphoid neogenesis. The success of B cell depletion therapy with rituximab, a monoclonal antibody directed against CD20 expressed by B cells, has further supported B cell intervention in RA development. Despite the efficacy of synthetic and biologic disease modifying anti-rheumatic drugs (DMARDs) in the treatment of RA, few patients reach sustained remission and refractory disease is a concern that needs critical evaluation and close monitoring. Janus kinase (JAK) inhibitors or JAKi are a new class of oral medications recently approved for the treatment of RA. JAK inhibitors suppress the activity of one or more of the JAK family of tyrosine kinases, thus interfering with the JAK-Signal Transducer and Activator of Transcription (STAT) signaling pathway. To date, there are five JAK inhibitors (tofacitinib, baricitinib, upadacitinib, peficitinib and filgotinib) approved in the USA, Europe and/ or Japan for RA treatment. Evidence from the literature indicates that JAK inhibitors interfere with B cell functions. In this review, the main results obtained in clinical trials, pharmacokinetic, in vitro and in vivo studies concerning the effects of JAK inhibitors on B cell immune responses in RA are summarized.