The effect of mild and moderate hepatic impairment on the pharmacokinetics of tofacitinib, an orally active Janus kinase inhibitor

The Impact of Baohuoside I on the Metabolism of Tofacitinib in Rats

Purpose

To study the potential drug-drug interactions between tofacitinib and baohuoside I and to provide the scientific basis for rational use of them in clinical practice.

Methods

A total of eighteen Sprague-Dawley rats were randomly divided into three groups: control group, single-dose group (receiving a single dose of 20 mg/kg of baohuoside I), and multi-dose group (receiving multiple doses of baohuoside I for 7 days). On the seventh day, each rat was orally administered with 10 mg/kg of tofacitinib 30 minutes after giving baohuoside I or vehicle. Blood samples were collected and determined using UPLC-MS/MS. In vitro effects of baohuoside I on tofacitinib was investigated in rat liver microsomes (RLMs), as well as the underlying mechanism of inhibition. The semi-inhibitory concentration value (IC50) of baohuoside I was subsequently determined and its inhibitory mechanism against tofacitinib was analyzed. Furthermore, the interactions between baohuoside I, tofacitinib and CYP3A4 were explored using Pymol molecular docking simulation.

Results

The administration of baohuoside I orally has been observed to enhance the area under the concentration-time curve (AUC) of tofacitinib and decrease the clearance (CL). The observed disparity between the single-dose and multi-dose groups was statistically significant. Furthermore, our findings suggest that the impact of baohuoside I on tofacitinib metabolism may be a mixture of non-competitive and competitive inhibition. Baohuoside I exhibit an interaction with arginine (ARG) at position 106 of the CYP3A4 enzyme through hydrogen bonding, positioning itself closer to the site of action compared to tofacitinib.

Conclusion

Our study has demonstrated the presence of drug-drug interactions between baohuoside I and tofacitinib, which may arise upon pre-administration of tofacitinib. Altogether, our data indicated that an interaction existed between tofacitinib and baohuoside I and additional cares might be taken when they were co-administrated in clinic.

Safety and Effectiveness of Tofacitinib in Treating Polyarticular Course Juvenile Idiopathic Arthritis

Polyarticular course juvenile idiopathic arthritis (pcJIA) is a form of arthritis that affects at least five joints at a time and presents before the age of 16. Its most common symptoms are pain, swelling, redness, and a limited range of motion, making it incredibly difficult for patients diagnosed to function in daily life. Historically, the leading treatment options have consisted of non-steroidal anti-inflammatory drugs (NSAIDs) and disease-modifying antirheumatic drugs (DMARDs) such as methotrexate. However, these drugs have serious toxic side effects associated with long-term use in addition to being ineffective in refractory cases. Recently, small molecule biologics have emerged as an alternate treatment to pcJIA. Tofacitinib is a small molecule JAK inhibitor that blocks the JAK/STAT cascade and decreases the transcription of genes responsible for immune function. We conducted a risk-benefit analysis to determine the viability of tofacitinib as a treatment for pcJIA. In our review, we found the side effect profile of tofacitinib to be relatively mild, with many of the serious adverse side effects occurring in those immunocompromised and those with impaired renal and hepatic metabolism. Overall, we have determined that tofacitinib has the potential to be effective in reducing flare-ups and lowering erythrocyte sedimentation rate (ESR) in immunocompetent patients with pcJIA. Additionally, our review has found that tofacitinib has the potential to be effective in patients who are refractory to traditional treatment. However, large-scale clinical trials are needed to determine if this effect holds true in younger pediatric populations, as limited data surrounds this demographic.

Iranian Consensus Guideline for Pharmacotherapy with Biologics and Small Molecules Drugs in Adults with Inflammatory Bowel Diseases

Background: Pharmacotherapy with biologics and small molecules, as the more effective therapies for moderate to severe ulcerative colitis (UC) and Crohn's disease (CD), is complex. Choosing the best methods for their utilization in order to induce and maintain remission are critical for practicing gastroenterologists. We aimed to develop an Iranian consensus on the management of inflammatory bowel disease (IBD) patients with biologics and small molecules. Methods: A Delphi consensus was undertaken by experts who performed a literature summary and voting process. Quality of evidence was assessed using the Grading and Recommendations Assessment, Development, and Evaluation; and an additional risk of bias-protocol. Results: Following an extensive search of the literature, 219 studies were used to determine the quality of the evidence. After three rounds of voting, consensus (defined as≥80% agreement) was reached for 87 statements. Conclusion: We considered different aspects of pharmacotherapy in this consensus. This guideline, along with clinical judgment, can be used to optimize management of IBD patients.

A randomized, crossover, phase I clinical study to evaluate bioequivalence and safety of tofacitinib and Xeljanz® in Chinese healthy subjects

OBJECTIVE

Tofacitinib is an oral Janus kinase (JAK) inhibitor that has been marketed and approved in the USA for the clinical treatment of rheumatoid arthritis, psoriasis and other inflammatory and autoimmune diseases. A phase I clinical trial was conducted to compare the bioequivalence and safety of tofacitinib (Chia Tai Tianqing Pharmaceutical Group Co., Ltd.) and Xeljanz® (Pfizer Inc.) in healthy Chinese subjects, providing basis for the clinical application of tofacitinib.

METHODS

Healthy Chinese subjects (N = 32) were randomly assigned to two groups at a 1:1 ratio. Subjects orally took 5 mg tofacitinib or Xeljanz® per cycle in random sequence. Blood samples were collected at 15 sampling points per cycle, and plasma drug concentrations of tofacitinib or Xeljanz® were analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and statistical analysis for the pharmacokinetic (PK) parameters. Subjects' physical indicators were monitored during the whole process to evaluate drug safety.

RESULTS

The adjusted geometric mean ratios (GMRs) of the peak concentration (C_max), area under the curve (AUC) from time zero to the last measurable concentration (AUC_0-t) and AUC from time zero to observed infinity (AUC_0-∞) were all within the range of 80-125%. The other PK parameter values were similar. The above values were all meeting the bioequivalence criteria with well safety.

CONCLUSION

The pharmacokinetic parameters and safety profile of tofacitinib were similar to those of Xeljanz® in healthy Chinese subjects. Therefore, tofacitinib can be considered bioequivalent to Xeljanz®, and the findings of this trial will promote the clinical application of tofacitinib.

Therapeutic Drug Monitoring for Current and Investigational Inflammatory Bowel Disease Treatments

This article reviews therapeutic drug monitoring (TDM) use for current inflammatory bowel disease (IBD) treatments. IBD comprises Crohn's disease and ulcerative colitis-chronic gastrointestinal inflammatory disorders. Treatment options for moderate to severe IBD include thiopurines; methotrexate; biologic agents targeting tumor necrosis factor, α4β7 integrin or interleukins 12 and 23; and Janus kinase inhibitors. TDM is recommended to guide treatment decisions for some of these agents. Published literature concerning TDM for IBD treatments was reviewed. S.D.L., R.S., and E.V.L. drew on their clinical experiences. Polymorphisms resulting in altered enzymatic activity inactivating thiopurine metabolites can lead to myelotoxicity and hepatotoxicity. Increased elimination of biologic agents can result from immunogenicity or higher disease activity, leading to low drug concentration and consequent nonresponse or loss of response. TDM may aid treatment and dose decisions for individual patients, based on monitoring metabolite levels for thiopurines, or serum drug trough concentration and antidrug antibody levels for biologic agents. Challenges remain around TDM implementation in IBD, including the lack of uniform assay methods and guidance for interpreting results. The Janus kinase inhibitor tofacitinib is not impacted by enzyme polymorphisms or disease activity, and is not expected to stimulate the formation of neutralizing antidrug antibodies. TDM is associated with implementation challenges, despite the recommendation of its use for guiding many IBD treatments. Newer small molecules with less susceptibility to patient variability factors may fulfill the unmet need of treatment options that do not require TDM, although further study is required to confirm this.

PK, PD, and interactions: the new scenario with JAK inhibitors and S1P receptor modulators, two classes of small molecule drugs, in IBD

INTRODUCTION

Inflammatory bowel diseases (IBDs) are immune-mediated chronic inflammatory disorders of the gastrointestinal tract whose pathogenesis is not yet fully understood. Despite the advent of biological agents, there are still unmet needs for IBD patients, due to suboptimal rate of sustained remission achieved. Small molecule drugs (SMDs), the next generation of selective drugs in IBD, show promising results in ongoing trials.

AREAS COVERED

We describe the pharmacodynamics and pharmacokinetic features of novel SMDs and their main differences with biologic agents.

EXPERT OPINION

Small molecule drugs are a promising class of drugs for the treatment of ulcerative colitis and Crohn's disease with good results in inducing and maintaining remission. Hence, over the next few years physicians will have numerous options of small molecule drugs for the treatment of patients with IBD. This group of drugs are potentially easier to use over biological agents due to pharmacokinetic features such as oral administration, short half-life, high volume of distribution, and lack of immunogenicity. On the other hand, drug-drug interactions can happen with small-molecule drugs, principally due to competitive metabolic and clearance mechanisms.

Clinical Pharmacology of Janus Kinase Inhibitors in Inflammatory Bowel Disease

Inflammatory bowel disease, including ulcerative colitis and Crohn's disease, are chronic inflammatory disorders of the gastrointestinal tract which are characterised, in part, by an imbalance in the production of several pro- and anti-inflammatory cytokines. Although various agents are effective for inducing and maintaining remission, approximately 20% of patients are treatment-refractory and require surgery. Parenterally administered monoclonal antibody-based biologics are associated with adverse effects resulting in treatment discontinuation and/or immunogenicity, leading to loss of response to therapy. Approximately 50% of patients who initially respond to treatment with tumour necrosis factor antagonists lose response to therapy within the 1st year of treatment. Incidence of immunogenicity tends to decrease over time, but once present can persist for years, even after treatment discontinuation. Nonimmunogenic oral small molecule therapies, including Janus kinase inhibitors, are currently being developed and have demonstrated efficacy in early phase clinical trials, which has already led to regulatory approval of tofacitinib for the treatment of patients with moderate-to-severe ulcerative colitis. Differentiation of T cells into T helper cells, which are mediators of the inflammatory response in inflammatory bowel disease, is mediated by the Janus kinase signal transducer and activator of the transcription signalling pathway. Absorption and distribution of Janus kinase inhibitors occurs at the site of action in the gastrointestinal tract, and newer compounds are being developed with limited systemic absorption, potentially reducing the risk of adverse effects. The current review describes the clinical pharmacology of approved Janus kinase inhibitors, as well as those in clinical development for the treatment of inflammatory bowel disease.

Application of Physiologically Based Pharmacokinetic Modeling to Predict Drug Exposure and Support Dosing Recommendations for Potential Drug-Drug Interactions or in Special Populations: An Example Using Tofacitinib

Tofacitinib is an oral Janus kinase inhibitor for the treatment of rheumatoid arthritis, psoriatic arthritis, and ulcerative colitis. It is eliminated via multiple pathways including oxidative metabolism (∼70%) and renal excretion (29%). This study aimed to predict the impact of drug‐drug interactions and renal or hepatic impairment on tofacitinib pharmacokinetics using a physiologically based pharmacokinetic (PBPK) model. The model was developed using Simcyp based on the physicochemical properties and in vitro and in vivo pharmacokinetics data for tofacitinib. The model was verified by comparing the predicted pharmacokinetic profiles with those observed in available clinical studies after single or multiple doses of tofacitinib, as well as with tofacitinib as a victim of drug‐drug interactions (because of inhibition of cytochrome P450 [CYP450] 3A4, CYP450 2C19, or CYP450 induction). In general, good agreement was observed between Simcyp predictions and clinical data. The results from this study provide confidence in using the PBPK modeling and simulation approach to predict the pharmacokinetics of tofacitinib under intrinsic (eg, renal or hepatic impairment) or extrinsic (eg, inhibition of CYP450 enzymes and/or renal transporters) conditions. This approach may also be useful in predicting pharmacokinetics under untested or complex situations (eg, when a combination of intrinsic and extrinsic factors may impact pharmacokinetics) when conducting clinical studies may be difficult, in response to health authority questions regarding dosing in special populations, or for labeling discussions.

Pharmacokinetics and Safety of a Single Oral Dose of Peficitinib (ASP015K) in Japanese Subjects With Normal and Impaired Hepatic Function

Peficitinib (ASP015K) is a novel Janus kinase inhibitor developed for the treatment of rheumatoid arthritis (RA). The impact of hepatic impairment on the peficitinib pharmacokinetic (PK) and safety profile was investigated in non‐RA subjects (n = 24) in an open‐label, parallel‐group, multicenter comparative study in Japan. Subjects received a single, clinically relevant, oral dose of a peficitinib 150 mg tablet under fasting conditions. Plasma PK parameters were measured for peficitinib and its metabolites H1 (sulfate and methylated metabolite), H2 (sulfate metabolite), and H4 (methylated metabolite) in subjects with normal hepatic function, mild hepatic impairment, or moderate hepatic impairment. The peficitinib area under the plasma‐concentration–time curve from time 0 to infinity (AUC_inf) and maximum observed concentration (C_max) were not markedly different in subjects with mild hepatic impairment versus normal hepatic function. In subjects with moderate hepatic impairment versus normal hepatic function, the geometric mean ratios for peficitinib AUC_inf and C_max, were 1.92 (90% CI: 1.39, 2.66) and 1.82 (90% CI: 1.24, 2.69), respectively. Five treatment‐emergent adverse events (TEAEs) were experienced by 3 subjects, 1 in each group. There were no deaths, no serious TEAEs, and no TEAEs leading to withdrawal. In summary, the PK profile was unaltered in subjects with mild hepatic impairment after a single clinically relevant dose of peficitinib, but exposure almost doubled in subjects with moderate hepatic impairment. Peficitinib dose reduction may be considered in RA patients with moderate hepatic impairment.

Dose-Dependent Pharmacokinetics of Tofacitinib in Rats: Influence of Hepatic and Intestinal First-Pass Metabolism

This study investigated the pharmacokinetics of tofacitinib in rats and the effects of first-pass metabolism on tofacitinib pharmacokinetics. Intravenous administration of 5, 10, 20, and 50 mg/kg tofacitinib showed that the dose-normalized area under the plasma concentration-time curve from time zero to infinity (AUC) was significantly higher at 50 mg/kg than at lower doses, a difference possibly due to saturation of the hepatic metabolism of tofacitinib. Oral administration of 10, 20, 50, and 100 mg/kg tofacitinib showed that the dose-normalized AUC was significantly higher at 100 mg/kg than at lower doses, a difference possibly due to saturation of the intestinal metabolism of tofacitinib. Following oral administration of 10 mg/kg tofacitinib, the unabsorbed fraction from the rat intestine was 3.16% and the bioavailability (F) was 29.1%. The AUC was significantly lower (49.3%) after intraduodenal, compared to intraportal, administration, but did not differ between intragastric and intraduodenal administration, suggesting that approximately 46.1% of orally administered tofacitinib was metabolized through an intestinal first-pass effect. The AUC was also significantly lower (42%) after intraportal, compared to intravenous, administration, suggesting that the hepatic first-pass effect on tofacitinib after entering the portal vein was approximately 21.3% of the oral dose. Taken together, these findings suggest that the low F of tofacitinib is due primarily to intestinal first-pass metabolism.

Frontiers in Drug Research and Development for Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is idiopathic, lifelong, immune-mediated diseases, for which curative therapies are not yet available. In the last 15 years, the introduction of monoclonal antibodies targeting tumor necrosis factor-α, a cytokine playing a key role in bowel inflammation, has revolutionized treatment paradigms for IBD. Despite their proven long-term efficacy, however, many patients do not respond or progressively lose response to these drugs. Major advances of knowledge in immunology and pathophysiology of intestinal inflammatory processes have made possible the identification of new molecular targets for drugs, thus opening several new potential therapeutic opportunities for IBD. The abnormal response of intestinal immunity to unknown antigens leads to the activation of T helper lymphocytes and triggers the inflammatory cascade. Sphingosine 1-phosphate receptor agonists negatively modulate the egress of lymphocytes, inducted by antigen-presenting cells, from secondary lymphoid tissues to intestinal wall. Leukocyte adhesion inhibitors (both anti-integrin and anti-Mucosal Vascular Addressin Cell Adhesion Molecule 1) interfere with the tissue homing processes. Activated T helper lymphocytes increase the levels of pro-inflammatory cytokines, such as interleukin 12, 23, and 6, offering several potential pharmacological interventions. The Janus kinases, intracellular enzymes mediating the transduction of several cytokine signals, are other explored targets for treating immune-mediated diseases. Finally, the impact of modulating Smad7 pathway, which is responsible for the down-regulation of the immunosuppressive cytokine transforming growth factor-β signaling, is currently under investigation. The purpose of this review is to discuss the most promising molecules in late-stage clinical development, with a special emphasis on pharmacological properties.