Safety, tolerability, and pharmacokinetics of single oral doses of tofacitinib, a Janus kinase inhibitor, in healthy volunteers

Clinical pharmacokinetics and pharmacodynamics of oral systemic nonbiologic therapies for psoriasis patients

INTRODUCTION

Psoriasis is a chronic inflammatory immune condition. Treatments for psoriasis vary with disease severity, ranging from topicals to systemic biologic agents. The pharmacokinetic (PK) and pharmacodynamic (PD) properties of these therapies establish drug efficacy, toxicity, and optimal dosing to ensure therapeutic drug levels are sustained and adverse effects are minimized.

AREAS COVERED

A literature search was performed on PubMed, Google Scholar, and Ovid MEDLINE for PK and PD, efficacy, and safety data regarding oral systemic nonbiologic therapies utilized for moderate-to-severe plaque psoriasis. The findings were organized into sections for each drug: oral acitretin, methotrexate, cyclosporine, apremilast, tofacitinib, and deucravacitinib.

EXPERT OPINION

Some psoriasis patients may not respond to initial therapy. Ongoing research is evaluating genetic polymorphisms that may predict an improved response to specific medications. However, financial and insurance barriers, as well as limited genetic polymorphisms correlated with treatment response, may restrict the implementation of genetic testing necessary to personalize treatments. How well psoriasis patients adhere to treatment may contribute greatly to variation in response. Therapeutic drug monitoring may help patients adhere to treatment, improve clinical response, and sustain disease control.

Clinical Pharmacokinetic and Pharmacodynamic Considerations in the Treatment of Moderate-to-Severe Psoriasis

Psoriasis is a common inflammatory immune disorder due to chronic activation of the adaptive and innate immune responses. Therapies for psoriasis target reducing inflammatory cytokines such as tumor necrosis factor-alpha, interleukin-17, and interleukin-22. Patients with inflammatory disorders have reduced metabolism by cytochrome P450 enzymes in the liver. The pharmacokinetic and pharmacodynamic changes due to psoriasis also have an impact on reaching therapeutic concentrations of the drug. Pharmacokinetic and pharmacodynamic data help determine the safety and clinical considerations necessary when utilizing drugs for plaque psoriasis. A literature search was performed on PubMed and Ovid MEDLINE for the pharmacokinetic and pharmacodynamic data of oral therapies and biologics utilized for moderate-to-severe plaque psoriasis. The findings from the literature search were organized into two sections: oral therapies and biologics. The pharmacokinetic and pharmacodynamic parameters in healthy patients, patients with psoriasis, and special populations are discussed in each section. The oral therapies described in this review include methotrexate, cyclosporine, apremilast, tofacitinib, and deucravacitinib. Biologics include tumor necrosis factor-alpha inhibitors, interleukin-17 inhibitors, ustekinumab, and interleukin-23 inhibitors. Clinical considerations for these therapies include drug toxicities, dosing frequency, and anti-drug antibodies. Methotrexate and cyclosporine have a risk for hepatoxicity and renal impairment, respectively. Moreover, drugs metabolized via cytochrome P450, including tofacitinib and apremilast have decreased clearance in patients with psoriasis, requiring dose adjustments. Patients treated with therapies such as adalimumab can develop anti-drug antibodies that reduce the long-term efficacy of the drug. Additionally, overweight patients benefit from more frequent dosing to achieve better psoriasis clearance.

Pharmacokinetics and bioequivalence of sunitinib and Sutent® in Chinese healthy subjects: an open-label, randomized, crossover study

Purpose: The purpose of this study was to examine the pharmacokinetics (PK), bioequivalence and safety of generic sunitinib and its original product Sutent® in healthy Chinese subjects through a phase-I clinical trial. Methods: The study selected two groups of 24 healthy Chinese subjects in a 1:1 ratio through random allocation. Each participant received either 12.5 mg of sunitinib or Sutent® per cycle. A total of 15 different time points were employed for blood sample collection during each cycle. Furthermore, a comprehensive assessment of the drugs' safety was consistently maintained throughout the trial. Results: The average adjusted geometric mean ratios (GMR) (90% CI) for the primary PK parameters Cmax, AUC0-t and AUC0-∞ were 97.04% (93.06%-101.19%), 98.45% (93.27%-103.91%) and 98.22% (93.15%-103.56%), respectively. The adjusted GMRs for essential pharmacokinetic (PK) parameters all met the requirements for bioequivalence, with values within the acceptable range of 80%-125%. In addition, the two drugs showed comparable results for the other PK parameters. These results indicate that the two drugs were bioequivalent. Furthermore, both drugs showed well safety. Conclusion: The research results proved that the PK and safety profiles of sunitinib in healthy Chinese subjects were comparable to those of Sutent®. These results advocate the clinical application of generic sunitinib as a potential alternative to original product Sutent® in the treatment of certain medical conditions.

Mass balance study of [14C]SHR0302, a selective and potent JAK1 inhibitor in humans

SHR0302, a selective JAK1 inhibitor developed by Jiangsu Hengrui Pharmaceutical Co., was intended for the treatment of rheumatoid arthritis. In this study, we evaluated the pharmacokinetics, mass balance, and metabolism of SHR0302 in six healthy Chinese male subjects after a single 8 mg (80 µCi) oral dose of [¹⁴C]SHR0302.SHR0302 was absorbed rapidly (T_max = 0.505 h), and the average t_1/2 of the SHR0302-related components in plasma was approximately 9.18 h. After an oral dose was administered, the average cumulative excretion of the radioactive components was 100.56% ± 1.51%, including 60.95% ± 11.62% in urine and 39.61% ± 10.52% in faeces.A total of 16 metabolites were identified. In plasma, the parent drug SHR0302 accounted for 90.42% of the total plasma radioactivity. In urine, SHR161279 was the main metabolite, accounting for 33.61% of the dose, whereas the parent drug SHR0302 only accounted for 5.1% of the dose. In faeces, the parent drug SHR0302 accounted for 23.73% of the dose, and SHR161279 was the significant metabolite, accounting for 5.67% of the dose. In conclusion, SHR0302-related radioactivity was mainly excreted through urine (60.95%) and secondarily through faeces (39.61%).The metabolic reaction of SHR0302 in the human body is mainly through mono-oxidation and glucuronidation. The main metabolic location of SHR0302 in the human body is the pyrrolopyrimidine ring.

Safety, tolerability and pharmacokinetics of WXFL10203614 in healthy Chinese subjects: A randomized, double-blind, placebo-controlled phase Ⅰ study

Objective: This study was conducted to investigate the safety, tolerability and pharmacokinetics (PK) of WXFL10203614 after single and multiple oral doses in healthy Chinese subjects.

Methods: A single-center, randomized, double-blind, placebo-controlled phase Ⅰ study was performed on healthy Chinese subjects. In the single-dose study, Subjects were randomized into 7 dose levels of WXFL10203614 (1 mg group, n = 2; 2, 5, 10, 17, 25 and 33 mg groups with placebo, 8 subjects per group, 2 of them given placebo). In the multiple-dose study, subjects received 5 or 10 mg WXFL10203614 once daily (QD), 5 mg twice daily (BID) or placebo for 7 consecutive days. Safety, tolerability and PK of WXFL10203614 were all assessed.

Results: A total of 592 subjects were screened, 50 subjects were enrolled in the single-dose study and 30 in the multiple-dose study. All adverse events (AEs) were mild or moderate and resolved spontaneously. No Serious Adverse Events (SAEs) or deaths were reported during the study. WXFL10203614 was absorbed rapidly after dosing with Tmax of 0.48–0.98 h, Cmax, AUC0-t and AUC0-∞ were all increased in a dose-related manner over the range of 1–33 mg. Renal excretion was the major route of elimination of WXFL10203614. Steady-state PK parameters (Cmax,ss, AUC0-t,ss and AUC0-∞,ss) were elevated after once-daily administration of 5–10 mg WXFL10203614 and non- and weak drug accumulations were observed, whereas moderate drug accumulation occurred in the 5 mg BID group.

Conclusion: WXFL10203614 exhibited good safety, tolerability and favorable PK profiles in healthy Chinese subjects, supporting further clinical development in patients with rheumatoid arthritis.

Clinical Trials Registration Number:http://www.chinadrugtrials.org.cn/index.html, #CTR20190069 and CTR20200143.

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.

Patients With Natural Killer (NK) Cell Chronic Active Epstein-Barr Virus Have Immature NK Cells and Hyperactivation of PI3K/Akt/mTOR and STAT1 Pathways

BACKGROUND

Chronic active Epstein-Barr virus (CAEBV) presents with high levels of viral genomes in blood and tissue infiltration with Epstein-Barr virus (EBV)-positive lymphocytes. The pathogenesis of CAEBV is poorly understood.

METHODS

We evaluated 2 patients with natural killer (NK) cell CAEBV and studied their NK cell phenotype and signaling pathways in cells.

RESULTS

Both patients had increased numbers of NK cells, EBV predominantly in NK cells, and immature NK cells in the blood. Both patients had increased phosphorylation of Akt, S6, and STAT1 in NK cells, and increased total STAT1. Treatment of 1 patient with sirolimus reduced phosphorylation of S6 in T and B cells, but not in NK cells and did not reduce levels of NK cells or EBV DNA in the blood. Treatment of both patients' cells with JAK inhibitors in vitro reduced phosphorylated STAT1 to normal. Patients with T- or B-cell CAEBV had increased phosphorylation of Akt and S6 in NK cells, but no increase in total STAT1.

CONCLUSIONS

The increase in phosphorylated Akt, S6, and STAT1, as well as immature NK cells describe a new phenotype for NK cell CAEBV. The reduction of STAT1 phosphorylation in their NK cells with JAK inhibitors suggests a novel approach to therapy.

Population Pharmacokinetics of Tofacitinib in Patients With Moderate to Severe Ulcerative Colitis

Tofacitinib is an oral, small molecule Janus kinase inhibitor for the treatment of ulcerative colitis (UC). We characterized tofacitinib pharmacokinetics in patients with moderate to severe UC, and the effects of covariates on variability in pharmacokinetic parameter estimates. Data were pooled from 1 8‐week phase 2 and 2 8‐week phase 3 induction studies, and a 52‐week phase 3 maintenance study (N = 1096). Population pharmacokinetic analysis was conducted using nonlinear mixed‐effects modeling. Potential predictors of apparent oral clearance (CL/F) and volume of distribution (V/F) were evaluated. The PK was described by a 1‐compartment model parameterized in terms of CL/F (26.3 L/hour [h]) and V/F (115.8 L), with first‐order absorption (K_a; 9.85 h⁻¹) and lag time (0.236 h). The derived elimination half‐life was approximately 3.05 h. In the final model, baseline creatinine clearance, sex, and race (Asian vs non‐Asian) were significant covariates for CL/F; significant covariates for V/F were age, sex, and body weight; baseline albumin and baseline Mayo score were not significant covariates. CL/F between‐patient variability was estimated at 22%. Tofacitinib exposure did not change significantly over the duration of induction/maintenance treatment in patients with UC. Although statistically significant covariate effects on CL/F and V/F were observed, the magnitude of the effects are not clinically significant. Therefore, dose adjustment/restrictions for age, body weight, sex, race, or baseline disease severity are not required during tofacitinib treatment. ClinicalTrials.gov numbers: NCT00787202, NCT01465763, NCT01458951, NCT01458574.

JAK out of the Box; The Rationale behind Janus Kinase Inhibitors in the COVID-19 setting, and their potential in obese and diabetic populations

The adaptive use of Janus kinase (JAK)-inhibitors has been suggested by rheumatology experts in the management of COVID-19. We recount the rationale behind their use in this setting, and the current evidence for and against their use in this review. JAK-inhibitors role in COVID-19 infection appears to be multifaceted, including preventing viral endocytosis and dampening the effect of excessive chemokines. This drug class may be able to achieve these effects at already preapproved dosages. Concerns arise regarding reactivation of latent viral infections and the feasibility of their use in those with severe disease. Most interestingly, JAK-Inhibitors may also have an additional advantage for diabetic and obese populations, where the dysregulation of JAK-signal transducer and activator of transcription pathway may be responsible for their increased risk of poor outcomes. Targeting this pathway may provide a therapeutic advantage for these patient groups.

Tofacitinib, the First Oral Janus Kinase Inhibitor Approved for Adult Ulcerative Colitis

Ulcerative colitis (UC) is a type of inflammatory bowel disease (IBD) characterized by chronic gastrointestinal inflammation. In most patients, the disease cycles through periods of remission and exacerbations. The complex etiology involves multiple factors including environmental, genetic, and immune causal elements. Janus Kinase (JAK) family is an essential component of a cytokine-signaling cascade partially responsible for the pathogenesis of UC. Treating UC presents difficulties despite various therapeutic options. Medications that block the JAK-signaling pathway can interfere with the inflammatory pathway of UC and possibly reduce symptoms and frequency of exacerbations. Tofacitinib is an oral pan-JAK inhibitor, primarily of JAK1 and JAK3, that was recently approved by the Food and Drug Administration (FDA) for the chronic treatment of UC in 2018. The following review describes the newly approved Janus kinase inhibitor, tofacitinib, including its pharmacokinetic properties, efficacy and safety data, and potential place in therapy.

The JAK1/3 inhibitor tofacitinib suppresses T cell homing and activation in chronic intestinal inflammation

BACKGROUND & AIMS

The molecular mechanism of action of the Janus kinase (JAK) inhibitor tofacitinib is poorly understood.

METHODS

Here, we analysed the inhibitory effect of tofacitinib on mucosal and blood T cells from patients with ulcerative colitis (UC). Furthermore tofacitinib treatment was analysed in experimental colitis models and wound healing. Additionally, tofacitinib effects were analysed in bioassays.

RESULTS

Tofacitinib significantly reduced T cell derived inflammatory cytokine production (Th2, Th9, Th17) in patients with active UC. Additionally, impaired expression of the homing receptors alpha4/beta1 and alpha4/beta7 as well as reduced gut homing capacity of T cells in a humanized mouse model of colitis were observed. Tofacitinib suppressed acute and chronic oxazolone colitis compared to untreated wild-type mice associated with downregulation of cytokines produced by Th2, Th9 and Th17 cells. Functionally, tofacitinib induced apoptosis of intestinal epithelial cells and prevented mucosal wound healing in vivo at higher concentration. Thus, our findings suggest that tofacitinib is quite effective in protecting from colitis by inhibition of a bundle of T cell derived cytokines like IL-5, IL-6, IL-9, IL-13 and IL-17A.

CONCLUSION

Application of tofacitinib emerges as an attractive concept for treatment of chronic intestinal inflammation at lower concentrations, whereas higher concentrations require attention due to prolonged wound healing.

Pharmacokinetics and Bioequivalence of 2 Immediate-Release Tofacitinib Tablet Formulations in Chinese Healthy Volunteers Under Fasting and Fed Conditions

The purpose of this study was to evaluate the bioequivalence of a generic immediate-release tofacitinib tablet versus a brand-named immediate-release tofacitinib tablet under fasting and fed conditions, and the food effect on pharmacokinetic profiles of the both formulations. This randomized, open-label, 2-period, crossover, bioequivalence study included 52 healthy Chinese subjects (fasting cohort: n = 26; fed cohort: n = 26). The subjects were assigned to receive a single 5-mg dose of generic or brand-named tofacitinib. Blood samples were collected at predosing and up to 14 hours after dosing. Tofacitinib concentrations in plasma were analyzed by high-performance liquid chromatography-tandem mass spectrometry. Safety was monitored. There were no significant differences in maximum plasma concentration, area under the plasma concentration-time curve from time zero to time t (AUC_0-t ), AUC from time zero to infinity (AUC_0-∞ )_, and terminal elimination half-life between the test and reference formulations (all P > .05); high-fat food had no significant effect on AUC_0-t , AUC_0-∞, or terminal elimination half-life of immediate-release tofacitinib tablets (all P > .05). The 90% confidence intervals of the test/reference ratios of log-transformed maximum plasma concentration, AUC_0-t , and AUC_0-∞ were within the range of 80% to 125% under both fasting and fed conditions. No serious adverse events were reported. The 2 formulations of immediate-release tofacitinib tablets are bioequivalent and well tolerated under both fasting and fed conditions in healthy Chinese volunteers. Food had no clinically relevant effects on drug exposure of tofacitinib.

Efficacy of JAK inhibitors in Crohn's Disease

Inhibition of Janus kinases [JAKs] in Crohn's disease [CD] patients has shown conflicting results in clinical trials. Tofacitinib, a pan-JAK inhibitor, showed efficacy in ulcerative colitis [UC] and has been approved for the treatment of patients with moderate to severe UC. In contrast, studies in CD patients were disappointing and the primary end point of clinical remission could not be met in the respective phase II induction and maintenance trials. Subsequently, the clinical development of tofacitinib was discontinued in CD. In contrast, efficacy of filgotinib, a selective JAK1 inhibitor, in CD patients was demonstrated in the randomized, double-blinded, placebo-controlled phase II FITZROY study. Upadacitinib also showed promising results in a phase II trial in moderate to severe CD. Subsequently, phase III programmes in CD have been initiated for both substances, which are still ongoing. Several newer molecules of this class of orally administrated immunosuppressants are being tested in clinical programmes. The concern of side effects of systemic JAK inhibition is addressed by either exclusively intestinal action or higher selectivity [Tyk2 inhibitors]. In general, JAK inhibitors constitute a new promising class of drugs for the treatment of CD.

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.

Combined anti-fibrotic and anti-inflammatory properties of JAK-inhibitors on macrophages in vitro and in vivo: Perspectives for scleroderma-associated interstitial lung disease

Janus kinase (JAK) inhibitors (also termed Jakinibs) constitute a family of small drugs that target various isoforms of JAKs (JAK1, JAK2, JAK3 and/or tyrosine kinase 2 (Tyk2)). They exert anti-inflammatory properties linked, in part, to the modulation of the activation state of pro-inflammatory M1 macrophages. The exact impact of JAK inhibitors on a wider spectrum of activation states of macrophages is however still to be determined, especially in the context of disorders involving concomitant activation of pro-inflammatory M1 macrophages and profibrotic M2 macrophages. This is especially the case in autoimmune pulmonary fibrosis like scleroderma-associated interstitial lung disease (ILD), in which M1 and M2 macrophages play a key pathogenic role. In this study, we directly compared the anti-inflammatory and anti-fibrotic effects of three JAK inhibitors (ruxolitinib (JAK2/1 inhibitor); tofacitinib (JAK3/2 inhibitor) and itacitinib (JAK1 inhibitor)) on five different activation states of primary human monocyte-derived macrophages (MDM). These three JAK inhibitors exert anti-inflammatory properties towards macrophages, as demonstrated by the down-expression of key polarization markers (CD86, MHCII, TLR4) and the limited secretion of key pro-inflammatory cytokines (CXCL10, IL-6 and TNFα) in M1 macrophages activated by IFNγ and LPS or by IFNγ alone. We also highlighted that these JAK inhibitors can limit M2a activation of macrophages induced by IL-4 and IL-13, as notably demonstrated by the down-regulation of the M2a associated surface marker CD206 and of the secretion of CCL18. Moreover, these JAK inhibitors reduced the expression of markers such as CXCL13, MARCO and SOCS3 in alternatively activated macrophages induced by IL-10 and dexamethasone (M2c + dex) or IL-10 alone (M2c MDM). For all polarization states, Jakinibs with inhibitory properties over JAK2 had the highest effects, at both 1 μM or 0.1 μM. Based on these in vitro results, we also explored the effects of JAK2/1 inhibition by ruxolitinib in vivo, on mouse macrophages in a model of HOCl-induced ILD, that mimics scleroderma-associated ILD. In this model, we showed that ruxolitinib significantly prevented the upregulation of pro-inflammatory M1 markers (TNFα, CXCL10, NOS2) and pro-fibrotic M2 markers (Arg1 and Chi3L3). These results were associated with an improvement of skin and pulmonary involvement. Overall, our results suggest that the combined anti-inflammatory and anti-fibrotic properties of JAK2/1 inhibitors could be relevant to target lung macrophages in autoimmune and inflammatory pulmonary disorders that have no efficient disease modifying drugs to date.

Preferential Inhibition of JAK1 Relative to JAK3 by Upadacitinib: Exposure-Response Analyses of Ex Vivo Data From 2 Phase 1 Clinical Trials and Comparison to Tofacitinib

Upadacitinib is a selective Janus kinase (JAK) 1 inhibitor being developed for treatment of rheumatoid arthritis. This study characterizes the relationships between upadacitinib exposure and interleukin (IL)-6-induced signal transducer and activator of transcription proteins 3 (STAT3) phosphorylation (pSTAT3) and IL-7-induced STAT5 phosphorylation (pSTAT5) in the ex vivo setting as measures for JAK1 and JAK1/JAK3 inhibition, respectively, with comparison to tofacitinib. Drug plasma concentrations and ex vivo IL-6-induced pSTAT3 and IL-7-induced pSTAT5 in blood from subjects evaluated in 2 phase 1 studies who received immediate-release 1 mg to 48 mg upadacitinib, 5 mg twice daily (BID) tofacitinib, or placebo were determined. Exposure-response models were developed, and the effects of different upadacitinib doses on ex vivo biomarker responses were simulated and compared to tofacitinib. Upadacitinib (and tofacitinib) reversibly inhibited IL-6-induced pSTAT3 and IL-7-induced pSTAT5 in a concentration-dependent manner. Model-estimated values of 50% of the maximum effect were 60.7 nM for upadacitinib and 119 nM for tofacitinib for IL-6-induced pSTAT3 inhibition, and 125 nM for upadacitinib and 79.1 nM for tofacitinib for IL-7-induced pSTAT5 inhibition. Tofacitinib 5 mg BID is estimated to have a similar magnitude of effect on IL-6-induced pSTAT3 to ∼3 mg BID of upadacitinib (immediate-release formulation), whereas a 4-fold higher dose of upadacitinib (∼12 mg BID), is estimated to show a similar magnitude of inhibition on IL-7-induced pSTAT5 as tofacitinb 5 mg BID. This study confirms that in humans, upadacitinib has greater selectivity for JAK1 vs JAK3 relative to the rheumatoid arthritis approved dose of tofacitinib, and results from these analyses informed the selection of upadacitinib IR doses evaluated in phase 2.

Profile of Tofacitinib in the Treatment of Ulcerative Colitis: An Evidence-Based Review of Recent Data

Recent advances in the understanding of the pathophysiology of ulcerative colitis (UC) have led to the expansion of our therapeutic arsenal. Conventional treatment options, including aminosalicylates, corticosteroids, thiopurines, and calcineurin inhibitors, fail to control the disease in a significant proportion of patients. Approximately 25-50% of the patients treated with tumor necrosis factor antibodies (anti-TNFα) are primary and secondary non-responders to therapy. Tofacitinib is a novel orally administered small synthetic molecule that inhibits a homologous family of enzymes, termed Janus kinases that modulate multiple key cytokines involved in the pathogenesis of UC. Phase II and III trials showed promising results in UC, leading the Food and Drug Administration (FDA) and the European Medicines Agency (EMA) to approve its administration for the induction and maintenance of remission in moderate-to-severe UC. Herein, we review tofacitinib for the management of UC, its mechanism of action pharmacokinetic properties, efficacy, and safety.

Phase 1 Dose-Escalation Study to Evaluate the Pharmacokinetics, Safety, and Tolerability of Tofacitinib in Japanese Healthy Volunteers

The aim of the study was to characterize the pharmacokinetics, safety, and tolerability of tofacitinib, an oral Janus kinase inhibitor for the treatment of rheumatoid arthritis, psoriatic arthritis, and ulcerative colitis in healthy Japanese volunteers, and to compare these outcomes with those of healthy Western volunteers. Twenty‐five volunteers (Japanese, n = 16; Western [white], n = 9) were randomized to receive either 3 escalating single doses of tofacitinib (1, 5, and 30 mg), single‐dose tofacitinib (15 mg) followed by multiple doses (15 mg twice daily for 5 days), or placebo. No significant differences in systemic exposure to tofacitinib were detected between the 2 ethnicities. Following single tofacitinib 1, 5, and 30 mg doses, mean area under the plasma concentration–time curve from time zero to infinity ratio (Japanese/Western) values were 96.6%, 93.5%, and 95.6%, respectively. Similarly, mean maximum observed plasma concentration ratio values were 99.5%, 118%, and 119%, respectively. Mean renal clearance was also similar, ranging across doses from 134 mL/min (5 mg) to 162 mL/min (1 mg) in Japanese volunteers, and 124 mL/min (30 mg) to 160 mL/min (1 mg) in Western volunteers. In both ethnicities, most adverse events were mild. No serious adverse events or deaths were reported. The pharmacokinetics of tofacitinib were well characterized in healthy Japanese volunteers and were similar to those in Western volunteers.

Modeling Combined Anti-Inflammatory Effects of Dexamethasone and Tofacitinib in Arthritic Rats

Tofacitinib (TOF), a Janus kinase (JAK) inhibitor, which was approved in 2012, has been recommended for the treatment of clinically active rheumatoid arthritis (RA). Dexamethasone (DEX), a potent corticosteroid, is also used in RA therapy but with limited usefulness due to dose- and time-dependent adverse effects. This pilot study examines the single and combined effects of DEX and TOF in order to explore the steroid-sparing potential of TOF. Collagen-induced arthritic (CIA) rats were subcutaneously (SC) dosed with vehicle, 1.5 mg/kg TOF, 5 mg/kg TOF, 0.225 mg/kg DEX, or a combination of 1.5 mg/kg TOF and 0.225 mg/kg DEX. Paw sizes were measured as an index of disease and drug efficacy and dynamically depicted using a logistic function for natural paw growth, a turnover model for disease progression, an indirect response model for inhibitory effects of TOF and DEX and a non-competitive interaction model for the combined effect of DEX and TOF. TOF alone exerted only a slight inhibitory effect on RA paw edema compared to DEX, which reduced edema by 40%. In combination, TOF and DEX had additive effects with an interaction factor of 0.76. Using model simulations, a single SC dose of TOF does not have a visible steroid-sparing potential, although BID oral dosing has such potential. The current study suggests an additive effect of TOF and DEX and simulations indicate that further exploration of TOF and DEX administration timing may produce desirable drug efficacy with lower DEX doses.

Discovery of a JAK1/3 Inhibitor and Use of a Prodrug To Demonstrate Efficacy in a Model of Rheumatoid Arthritis

The four members of the Janus family of nonreceptor tyrosine kinases play a significant role in immune function. The JAK family kinase inhibitor, tofacitinib 1, has been approved in the United States for use in rheumatoid arthritis (RA) patients. A number of JAK inhibitors with a variety of JAK family selectivity profiles are currently in clinical trials. Our goal was to identify inhibitors that were functionally selective for JAK1 and JAK3. Compound 22 was prepared with the desired functional selectivity profile, but it suffered from poor absorption related to physical properties. Use of the phosphate prodrug 32 enabled progression to a murine collagen induced arthritis (CIA) model. The demonstration of a robust efficacy in the CIA model suggests that use of phosphate prodrugs may resolve issues with progressing this chemotype for the treatment of autoimmune diseases such as RA.

Systemic Tofacitinib Concentrations in Adult Patients With Atopic Dermatitis Treated With 2% Tofacitinib Ointment and Application to Pediatric Study Planning

Atopic dermatitis is a chronic eczematous, pruritic, inflammatory skin condition affecting children and adults. Tofacitinib is a Janus kinase inhibitor. The efficacy, safety, and pharmacokinetics of 2% tofacitinib ointment twice daily have been evaluated in a 4‐week phase 2a multisite randomized, double‐blind, vehicle‐controlled, parallel‐group study (NCT02001181) in adult patients with mild to moderate atopic dermatitis and 2% to 20% body surface area (BSA) involvement. Tofacitinib ointment demonstrated significantly greater efficacy versus vehicle for all efficacy end points and had an acceptable safety profile. Predose and postdose pharmacokinetic samples were collected in week 2 and week 4. The objective of this analysis was to assess if predicted mean tofacitinib concentrations with topical application at higher treated BSA across age groups would exceed relevant concentration thresholds based on oral doses of tofacitinib. In this analysis, the pharmacokinetic concentrations were characterized using a linear mixed‐effects model. The model was used to predict concentrations for adults with higher (>20%) treatable BSA. Adult concentrations were used to extrapolate concentrations to a pediatric population (2 to 17 years) using allometric principles. The predicted systemic concentrations for 2% tofacitinib ointment in both adult and pediatric populations at treated BSA ≤50% for a mild to moderate atopic dermatitis population did not exceed those reported for the 10th percentile of observed oral tofacitinib 5‐mg twice‐daily doses in patients with moderate to severe plaque psoriasis. The methodology described will enable analysis and prediction of systemic concentrations for topical agents.

The 2018 pipeline of targeted therapies under clinical development for Systemic Lupus Erythematosus: a systematic review of trials

Currently, Systemic Lupus Erythematosus (SLE) therapies range from antimalarials to glucocorticoids, in addition to immunosupressive agents or biologics such as rituximab or belimumab, when needed. Several unmet needs remain in the treatment SLE and more targeted drugs with improved safety profiles are expected. Based on recent advances in the understanding of the complex pathogenesis of SLE, several targeted treatments are currently assessed in clinical trials. In this study, we performed a systematic review of all targeted therapies under clinical development in SLE in 17 online registries of clinical trials. The search yielded a total of 1140 trials, from which we identified 74 targeted therapies for SLE. Those treatments target inflammatory cytokines, chemokines, or their receptors (n = 17), B cells or plasma cells (n = 17), intracellular signalling pathways (n = 10), T/B cells costimulation molecules (n = 8), interferons (n = 7), plasmacytoid dendritic cells (pDC) (n = 3), as well as various other targets (n = 12). Not all these candidate drugs will reach phase III, but the broad spectrum of drugs being investigated may satisfy the urgent need for improved lupus medications. The identification of biomarkers that would allow adequate prediction of response-to-therapy remains high, but when solved will allow a more rationale selection of the optimal pharmacological agent at the patient level.

Evaluation of a Janus kinase 1 inhibitor, PF-04965842, in healthy subjects: A phase 1, randomized, placebo-controlled, dose-escalation study

AIMS

To determine the safety, tolerability, pharmacokinetics and pharmacodynamics of the Janus kinase 1-selective inhibitor, PF-04965842.

METHODS

This was a phase 1, first-in-human, randomized, double-blind, placebo-controlled, combination single- and multiple-dose escalation, parallel design study in healthy subjects (http://clinicaltrials.gov, NCT01835197). Subjects received a single dose of placebo or 3, 10, 30, 100, 200, 400 or 800 mg PF-04965842 (single ascending dose phase) and placebo or 30 mg once daily (QD), 100 mg QD, 200 mg QD, 400 mg QD, 100 mg twice daily (BID) or 200 mg BID PF-04965842 for 10 consecutive days (multiple ascending dose phase). The primary objective was to determine the safety and tolerability of PF-04965842.

RESULTS

Seventy-nine subjects were randomized and received study treatments. There were no deaths or serious adverse events. The most frequent treatment-emergent adverse events were headache (n = 13), diarrhoea (n = 11) and nausea (n = 11). PF-04965842 was absorbed rapidly (median time at which maximum plasma concentration occurred generally ≤1 h following either single- or multiple-dose administration) and eliminated rapidly (mean t_½ 2.8-5.2 h after 10 days of QD or BID administration in the multiple ascending dose phase). Increases in maximum plasma concentration and area under the concentration-time curve were dose proportional up to 200 mg (single or total daily doses) with an apparent trend towards greater than proportional increases with higher doses. Less than 4.4% of the dose was recovered unchanged in urine. Changes in pharmacodynamic biomarkers were consistent with the known effects of Janus kinase signalling inhibition.

CONCLUSIONS

These results support further evaluation of PF-04965842 for clinical use in patients with inflammatory diseases.

Interleukin-2 shapes the cytotoxic T cell proteome and immune environment-sensing programs

Interleukin-2 (IL-2) and Janus kinases (JAKs) regulate transcriptional programs and protein synthesis to promote the differentiation of effector CD8⁺ cytotoxic T lymphocytes (CTLs). Using high-resolution mass spectrometry, we generated an in-depth characterization of how IL-2 and JAKs configure the CTL proteome to control CTL function. We found that IL-2 signaling through JAK1 and JAK3 (JAK1/3) increased the abundance of a key subset of proteins to induce the accumulation of critical cytokines and effector molecules in T cells. Moreover, IL-2 maintained the concentration of proteins that support core metabolic processes essential for cellular fitness. One fundamental insight was the dominant role for IL-2 in stimulating effector T cells to detect microenvironmental cues. IL-2-JAK1/3 signaling pathways thus increased the abundance of nutrient transporters, nutrient sensors, and critical oxygen-sensing molecules. These data provide key insights into how IL-2 promotes T cell function and highlight signaling mechanisms and transcription factors that integrate oxygen sensing to transcriptional control of CD8⁺ T cell differentiation.

Intestinally-restricted Janus Kinase inhibition: a potential approach to maximize the therapeutic index in inflammatory bowel disease therapy

Background

An unmet need remains for safe and effective treatments to induce and maintain remission in inflammatory bowel disease (IBD) patients. The Janus kinase (JAK) inhibitor, tofacitinib, has demonstrated robust efficacy in ulcerative colitis patients although, like other systemic immunosuppressants, there may be safety concerns associated with its use. This preclinical study evaluated whether modulating intestinal inflammation via local JAK inhibition can provide efficacy without systemic immunosuppression.

Methods

The influence of tofacitinib, dosed orally or intracecally, on oxazolone-induced colitis, oxazolone or interferon-γ (IFNγ)-induced elevation of colonic phosphorylated signal transducer and activator of transcription1 (pSTAT1) levels, and basal splenic natural killer (NK) cell counts was investigated in mice.

Results

Tofacitinib, dosed orally or intracecally, inhibited, with similar efficacy, oxazolone-induced colitis, represented by improvements in the disease activity index and its sub-scores (body weight, stool consistency and blood content). Intracecal dosing of tofacitinib resulted in a higher colon:plasma drug exposure ratio compared to oral dosing. At equieffective oral and intracecal doses, colonic levels of tofacitinib were similar, while the plasma levels for the latter were markedly lower, consistent with a lack of effect on splenic NK cell counts. Tofacitinib, dosed orally, intracecally, or applied to the colonic lumen in vitro, produced dose-dependent, and maximal inhibition of oxazolone or IFNγ-induced STAT1 phosphorylation in the colon.

Conclusions

Localized colonic JAK inhibition, by intracecal delivery of tofacitinib, provides colonic target engagement and efficacy in a mouse colitis model at doses which do not impact splenic NK cell counts. Intestinal targeting of JAK may permit separation of local anti-inflammatory activity from systemic immunosuppression, and thus provide a larger therapeutic index compared to systemic JAK inhibitors.

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.