Efficacy and safety of filgotinib in Japanese patients with refractory rheumatoid arthritis: Subgroup analyses of a global phase 3 study (FINCH 2)

Filgotinib in rheumatoid arthritis

INTRODUCTION

Rheumatoid Arthritis (RA) remains a challenge for rheumatologists and patients despite implementation of intensive treat-to-target strategies in shared decision with patients and an increasing availability of drugs. Janus kinase inhibitors (JAKi) are a new generation of oral targeted drugs. Filgotinib preferentially inhibits JAK1 and is the latest JAKi to be approved for use in RA.

AREAS COVERED

This narrative review focuses on drug characteristics, efficacy, and safety of filgotinib in patients with RA, summarizing available literature. Trial data are detailed, put into perspective for practice and discussed in regulatory perspective.

EXPERT OPINION

Preclinical studies demonstrate preferential inhibition of JAK1 and a promising pharmacokinetic profile with few drug-drug interactions. Increase in hemoglobin in line with preferential inhibition of JAK1 over JAK2 is seen in early-phase clinical trials. A phase III program demonstrates efficacy in several disease stages, numerically higher with 200 mg versus 100 mg daily. In the overall RA population such dose-related effect is not observed for safety except for herpes zoster and increases in lipids and creatine phosphokinase. This reassuring safety profile is to be confirmed in future practice. It also needs to be unraveled if JAK1 preferential inhibition plays a key role in this safety profile.

Safety and Efficacy of Filgotinib for Japanese Patients with RA and Inadequate Response to MTX: FINCH 1 52-Week Results and FINCH 4 48-Week Results

OBJECTIVE

To present safety and efficacy of the JAK1 preferential inhibitor filgotinib in Japanese patients with prior inadequate response (IR) to methotrexate (MTX) from a 52-week randomised controlled parent study (PS) and long-term extension (LTE) through June 2020.

METHODS

The PS (NCT02889796) randomised MTX-IR patients to filgotinib 200 (FIL200) or 100 mg (FIL100), adalimumab (ADA) 40 mg, or placebo; all took stable background MTX. At week (W) 24, placebo patients were rerandomised to FIL200 or FIL100. The primary endpoint was W12 American College of Rheumatology 20% improvement (ACR20); safety was assessed by adverse event (AE) reporting. For the LTE (NCT03025308), eligible filgotinib patients continued FIL200/FIL100; ADA patients were rerandomised (blinded) to FIL200 or FIL100; all continued MTX.

RESULTS

114/147 Japanese patients completed the PS; 115 enrolled in LTE; 103 remained on study in June 2020. In the PS, AEs were consistent with the overall population, and W24 efficacy was maintained or improved through W52, comparable with the overall population. LTE AE incidences were similar between doses; filgotinib efficacy was consistent from baseline to W48 and similar between PS ADA and filgotinib patients.

CONCLUSION

Among MTX-IR Japanese patients, filgotinib maintained efficacy over 1 year; LTE safety was consistent with the PS.

Long-Term Safety and Efficacy of Filgotinib Treatment for Rheumatoid Arthritis in Japanese Patients Naïve to MTX Treatment (FINCH 3)

OBJECTIVES

To evaluate long-term safety and efficacy of filgotinib for Japanese patients with rheumatoid arthritis (RA) and limited/no prior methotrexate (MTX) exposure. We present a Japanese population subanalysis of a global randomised-controlled trial at Week 52 and interim long-term extension (LTE) to Week 48 through June 2020.

METHODS

Patients were randomised to filgotinib 200 mg plus MTX, filgotinib 100 mg plus MTX, filgotinib 200 mg, or MTX for 52 weeks. At completion, eligible patients could enrol in the LTE. Those receiving filgotinib continued; those receiving MTX were rerandomised (blinded) to filgotinib 200 or 100 mg upon discontinuation of MTX. After a 4-week washout period, MTX could be re-added.

RESULTS

Adverse event rates at Week 52 and in the LTE to Week 48 were comparable across treatment groups. Week 52 American College of Rheumatology 20% improvement (ACR20) rates were 83% (19/23), 82% (9/11), 75% (9/12), and 76% (19/25) for filgotinib 200 mg plus MTX, filgotinib 100 mg plus MTX, filgotinib 200 mg, and MTX, respectively. Through LTE Week 48, ACR20 rates were maintained.

CONCLUSIONS

In the 56 Japanese patients treated with filgotinib, efficacy was maintained through Week 52 and beyond, with no increases in the incidence of adverse events.

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.