A Novel LC-MS/MS Method for Therapeutic Drug Monitoring of Baricitinib in Plasma of Pediatric Patients

BACKGROUND

Janus kinase inhibitors are antirheumatic immunosuppressive drugs that target intracellular Janus kinases (JAKs). Baricitinib is a selective and reversible orally administered JAK1/JAK2 inhibitor approved for treating rheumatoid arthritis, atopic dermatitis, and alopecia areata in adult patients. Expanded access to baricitinib has been approved for treating pediatric patients affected by rare Mendelian autoinflammatory diseases with type I interferon-mediated damage. Knowledge of the pharmacokinetic properties and target plasma levels of baricitinib in pediatric patients is limited. In this study, a novel LC-MS/MS method for measuring baricitinib in plasma, validated according to the ICH M10 guidelines, is presented.

METHODS

Sample preparation was performed by adding 10 µL of IS working solution (150 ng/mL) and 200 µL of MeOH to each plasma sample. Chromatographic separation was conducted using a Thermo Scientific Accucore Polar Premium column (50 mm × 2.1 mm, i.d. 2.6 m). This method was applied to 7 real anonymous plasma samples obtained from pediatric patients treated with baricitinib at IRCCS Istituto Giannina Gaslini (Genoa, Italy). Patients of both sexes had a median age of 14 years (range, 10-17 years).

RESULTS

The LC-MS/MS method resulted linear over wide concentration ranges (1.024-100 ng/mL) and was accurate and reproducible in the absence of matrix effects, allowing for robust, specific, and rapid quantification of baricitinib from a low amount of plasma (50 µL). The plasma concentration of baricitinib in the samples of the patients, expressed as mean ± SD, was 11.25 ± 10.86 ng/mL.

CONCLUSIONS

This novel LC-MS/MS method is suitable for the therapeutic drug monitoring of baricitinib and can help guide therapy optimization in pediatric patients.

Pharmacokinetic characteristics of golidocitinib, a highly selective JAK1 inhibitor, in healthy adult participants

Background

Golidocitinib is an orally available, potent and highly selective JAK (Janus kinase)-1 inhibitor of JAK/STAT3 signaling under clinical development for the treatment of cancer and autoimmune diseases. The objectives of the two reported studies were to investigate the pharmacokinetics (PK), safety, and tolerability of golidocitinib in healthy Chinese participants as compared to those healthy Western participants, as well as the food effect exploration.

Methods

Two phase I studies (JACKPOT2 and JACKPOT3) were conducted in USA and China, respectively. In JACKPOT2 study, participants were randomized into placebo or golidocitinib arm in single-ascending dose cohorts (5 - 150 mg) and multiple-ascending dose cohorts (25 - 100 mg, once daily) for 14 days. In the food effect cohort, golidocitinib (50 mg) was administrated shortly after a high-fat meal (fed conditions) as compared to under fasting conditions. In JACKPOT3 study conducted in China, participants were randomized to placebo or golidocitinib arm in single-ascending dose cohorts (25 - 150 mg).

Results

Exposure of golidocitinib generally increased in a dose-proportional manner across a dose range of 5 mg to 150 mg (single dose) and 25 mg to 100 mg (once daily). High-fat food did not alter the PK of golidocitinib with statistical significance. Low plasma clearance and extensive volume of distribution characterizes PK of golidoctinib, and long half-life across the dose levels supported once daily dosing. The inter-ethnic difference in primary PK parameters was evaluated. The result suggested slightly higher peak plasma concentrations (Cmax) but comparable area under the plasma concentration-time curve (AUC) was observed in Asian (Chinese) subjects as compared to Caucasian and/or Black subjects, while it was not considered clinically relevant. Golidocitinib was well tolerated without Common Terminology Criteria for Adverse Events (CTCAE) grade 3 or higher drug-related treatment emergent adverse events (TEAE) reported.

Conclusion

No noticeable inter-ethnic difference was observed among Asian, Black, and Caucasian healthy subjects in anticipation of the favorable PK properties of golidocitinib. The effect of food on the bioavailability of golidocitinib was minor following a single oral administration of 50 mg. These data guided to use the same dose and regimen for multinational clinical development.

Clinical trial registrations

https://clinicaltrials.gov/ct2/show/NCT03728023?term=NCT03728023&draw=2&rank=1, identifier (NCT03728023); http://www.chinadrugtrials.org.cn/clinicaltrials.searchlistdetail.dhtml, identifier (CTR20191011).

Pharmacokinetics of Ruxolitinib in Patients with Atopic Dermatitis Treated With Ruxolitinib Cream: Data from Phase II and III Studies

BACKGROUND

Pathogenesis of atopic dermatitis (AD) involves the Janus kinase (JAK)/signal transducer and activator of transcription (STAT) pathway. A cream formulation of ruxolitinib, a potent selective JAK1/JAK2 inhibitor, was developed for topical delivery.

METHOD

Pharmacokinetic data were obtained from three double-blind, vehicle-controlled studies in patients with AD: a phase II study with ruxolitinib cream 0.15%, 0.5%, or 1.5% once daily or 1.5% twice daily (BID), and two phase III studies with 0.75% or 1.5% BID. Effects of baseline characteristics on pharmacokinetics were examined. Correlations were attempted between plasma concentrations and change in hematological parameters over time.

RESULTS

Ruxolitinib plasma concentrations at steady-state (Css) increased with cream strength in a less-than-dose-proportional manner. In the phase III studies, overall mean (standard deviation [SD]) Css after ruxolitinib cream 0.75% and 1.5% BID (23.8 [35.0] and 35.7 [55.0] nM) were a fraction of the half-maximal inhibitory concentration for thrombopoietin-stimulated phosphorylated STAT3 inhibition (281 nM), a JAK/STAT signaling marker. Three covariates were identified for Css: dose, percent body surface area (%BSA) treated, and baseline Investigator's Global Assessment score. Mean (SD) bioavailability of ruxolitinib cream 1.5% BID was 6.22% (7.66%). There were no correlations between Css and any hematological changes except for a transient increase in platelets at week 2.

CONCLUSIONS

Plasma ruxolitinib concentrations after treatment with topical ruxolitinib cream in patients with up to 20% BSA affected by AD are not expected to lead to systemic plasma concentrations that may be associated with adverse effects commonly associated with oral JAK inhibitors. CLINICALTRIALS.GOV: NCT03011892; NCT03745638; NCT03745651.

Effects of Hepatic Impairment on the Pharmacokinetics of Abrocitinib and Its Metabolites

Abrocitinib, an oral once-daily Janus kinase 1 selective inhibitor, is under development for treatment of atopic dermatitis. This phase 1, nonrandomized, open-label, single-dose study (NCT03626415) investigated the effect of hepatic impairment on pharmacokinetics (PK), safety, and tolerability of abrocitinib and its metabolites after a 200-mg oral dose. Twenty-four subjects with varying degrees of hepatic function (normal, mild, and moderate impairment) were enrolled (N = 8/group). Active moiety PK parameters were calculated as the sum of unbound PK parameters for abrocitinib and its active metabolites. For abrocitinib, the ratios (percentages) of adjusted geometric means for area under the concentration-time curve from time 0 extrapolated to infinite time (AUC_inf ) and maximum plasma concentration (C_max ) were 133.33 (90% confidence interval [CI], 86.17-206.28) and 94.40 (90%CI, 62.96-141.55), respectively, for subjects with mild hepatic impairment vs normal hepatic function. The corresponding comparisons of ratios (percentages) for AUC_inf and C_max were 153.99 (90%CI, 99.52-238.25) and 105.53 (90%CI, 70.38-158.24), respectively, for subjects with moderate hepatic impairment. Exposures of the metabolites were generally lower in subjects with hepatic impairment. For abrocitinib active moiety, the ratios (percentages) of adjusted geometric means of unbound AUC_inf were 95.74 (90%CI, 72.71-126.08) and 114.82 (90%CI, 87.19-151.20) in subjects with mild and moderate impairment vs normal hepatic function, respectively. Abrocitinib was generally safe and well tolerated. Hepatic impairment had no clinically relevant effect on the PK and safety of abrocitinib and the exposure of abrocitinib active moiety. These results support the use of abrocitinib without dose adjustment in subjects with mild or moderate hepatic impairment.

Characterization of the Effect of Upadacitinib on the Pharmacokinetics of Bupropion, a Sensitive Cytochrome P450 2B6 Probe Substrate

This phase 1 study characterized the effect of multiple doses of upadacitinib, an oral Janus kinase 1 selective inhibitor, on the pharmacokinetics of the cytochrome P450 (CYP) 2B6 substrate bupropion. Healthy subjects (n = 22) received a single oral dose of bupropion 150 mg alone (study period 1) and on day 12 of a 16-day regimen of upadacitinib 30 mg once daily (study period 2). Serial blood samples for measurement of bupropion and hydroxybupropion plasma concentrations were collected in each study period. The central values (90% confidence intervals) for the ratios of change were 0.87 (0.79-0.96) for bupropion maximum plasma concentration (Cmax ), 0.92 (0.87-0.98) for bupropion area under the plasma-concentration time curve from time 0 to infinity (AUCinf ), 0.78 (0.72-0.85) for hydroxybupropion Cmax , and 0.72 (0.67-0.78) for hydroxybupropion AUCinf when administered with, relative to when administered without, upadacitinib. After multiple-dose administration of upadacitinib 30 mg once daily, upadacitinib mean ± SD AUC0-24 was 641 ± 177 ng·h/mL, and Cmax was 83.3 ± 30.7 ng/mL. These results confirm that upadacitinib has no relevant effect on pharmacokinetics of substrates metabolized by CYP2B6.

Safety of Janus Kinase Inhibitors in Older Patients: A Focus on the Thromboembolic Risk

The Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway is a membrane-to-nucleus signaling cascade that effects activation of gene transcription. JAK inhibitors have demonstrated effectiveness in autoimmune diseases such as rheumatoid arthritis. An increased risk of infection, mainly varicella-zoster reactivation, with these new agents is of concern. Comorbid conditions, along with pharmacokinetic variations in drug metabolism in the older population, further increase the risk of adverse outcomes. Newly raised concerns for potential adverse effects such as deep vein thrombosis and pulmonary embolism are essential considerations for clinicians. Older patients are at increased risk because of multiple comorbid conditions and pharmacokinetic changes related to drug metabolism and excretion. Both the US FDA and the European Medicines Agency have issued warnings regarding this risk. These warnings highlight individuals aged > 50 years with concomitant cardiovascular risk factors. Furthermore, the FDA released a black box warning for increased thromboembolic risk associated with JAK inhibitors. As the use of these drugs increases, a solid understanding of adverse effects and risks is critical to those treating older adults.

Clinical Pharmacokinetics of Upadacitinib: Review of Data Relevant to the Rheumatoid Arthritis Indication

Upadacitinib is a Janus kinase 1 inhibitor developed for treatment of moderate to severe rheumatoid arthritis (RA) and was recently approved by the US Food and Drug Administration for this indication in adults who have had an inadequate response or intolerance to methotrexate. Upadacitinib is currently under regulatory review by other agencies around the world. Ongoing trials are investigating the use of upadacitinib in other inflammatory autoimmune diseases. In this article, we review the clinical pharmacokinetic data available to date for upadacitinib that supported the clinical development program in RA and ultimately regulatory applications for upadacitinib in treatment of patients with moderate to severe RA.

Development and validation of a Level A in-vitro in-vivo correlation for tofacitinib modified-release tablets using extrudable core system osmotic delivery technology

PURPOSE

To determine if a validated Level A in-vitro in-vivo correlation (IVIVC) could be achieved with the extrudable core system (ECS) osmotic tablet platform. Tofacitinib is an oral JAK inhibitor for the treatment of rheumatoid arthritis.

METHODS

Fast-, medium-, and slow-release modified-release formulations of 11 mg tofacitinib ECS tablets, and one formulation of 22 mg tofacitinib ECS tablet, were manufactured. In vitro dissolution of the tofacitinib ECS tablets was performed using USP Apparatus 2 (paddles) and in vivo pharmacokinetic (PK) data were obtained from a Phase 1 study in healthy volunteers. A 5 mg immediate-release formulation tablet was included to support deconvolution of the tofacitinib ECS PK tablet data to obtain the in vivo absorption profiles. A linear, piecewise correlation and a simple linear correlation were used to build and validate two IVIVC models.

RESULTS

The prediction errors (PEs) for the linear, piecewise correlation met the Food and Drug Administration's criteria for establishing a Level A IVIVC, with a maximum absolute individual internal PE of 4.6%, a maximum absolute average internal PE of 3.9%, and a maximum absolute external PE of 8.4% obtained.

CONCLUSIONS

This study demonstrates that the tofacitinib ECS osmotic tablet platform can achieve a Level A IVIVC, similar to other osmotic delivery systems.

A Hydrophilic Interaction Liquid Chromatography-Tandem Mass Spectrometry Quantitative Method for Determination of Baricitinib in Plasma, and Its Application in a Pharmacokinetic Study in Rats

Baricitinib, is a selective and reversible Janus kinase inhibitor, is commonly used to treat adult patients with moderately to severely active rheumatoid arthritis (RA). A fast, reproducible and sensitive method of liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the quantification of baricitinib in rat plasma has been developed. Irbersartan was used as the internal standard (IS). Baracitinib and IS were extracted from plasma by liquid-liquid extraction using a mixture of n-hexane and dichloromethane (1:1) as extracting agent. Chromatographic separation was performed using Acquity UPLC HILIC BEH 1.7 µm 2.1 × 50 mm column with the mobile phase consisting of 0.1% formic acid in acetonitrile and 20 mM ammonium acetate (pH 3) (97:3). The electrospray ionization in the positive-mode was used for sample ionization in the multiple reaction monitoring mode. Baricitinib and the IS were quantified using precursor-to-production transitions of m/z 372.15 > 251.24 and 429.69 > 207.35 for baricitinib and IS, respectively. The method was validated according to the recent FDA and EMA guidelines for bioanalytical method validation. The lower limit of quantification was 0.2 ng/mL, whereas the intra-day and inter-day accuracies of quality control (QCs) samples were ranged between 85.31% to 89.97% and 87.50% to 88.33%, respectively. Linearity, recovery, precision, and stability parameters were found to be within the acceptable range. The method was applied successfully applied in pilot pharmacokinetic studies.

The oral Janus kinase/spleen tyrosine kinase inhibitor ASN002 demonstrates efficacy and improves associated systemic inflammation in patients with moderate-to-severe atopic dermatitis: results from a randomized double-blind placebo-controlled study

BACKGROUND

ASN002 is an oral dual inhibitor of Janus kinase and spleen tyrosine kinase, which are involved in the pathogenesis of atopic dermatitis (AD) through their regulatory role on T helper (Th)1, Th2 and Th17/Th22 pathways.

OBJECTIVES

The objectives of this study were to evaluate the efficacy, safety, pharmacokinetics and effects on systemic biomarkers of ASN002 in patients with moderate-to-severe AD. Methods A total of 36 patients with moderate-to-severe AD were randomized (3 : 1) to ASN002 or placebo in the phase Ib study. Three dosage cohorts were studied over a 28-day period (20 mg, 40 mg and 80 mg once daily).

RESULTS

ASN002 was superior to placebo for the proportion of patients achieving Eczema Area and Severity Index (EASI) 50 (20 mg 20%, P = 0·93; 40 mg 100%, P = 0·003; 80 mg 83%, P = 0·03; placebo 22%), EASI 75 (20 mg 0%, P = 0·27; 40 mg 71%, P = 0·06; 80 mg 33%, P = 0·65; placebo 22%) and in change from baseline in pruritus (20 mg -1·3 ± 2·1, P = 0·81; 40 mg -3·1 ± 2·7, P = 0·27; 80 mg -4·7 ± 2·1, P = 0·01; placebo -1·6 ± 1·8). Adverse events were generally mild and similar across all groups. ASN002 showed dose-dependent plasma exposure with low interpatient variability, significantly downregulated several serum biomarkers involved in Th1, Th2 and Th17/Th22 immunity, and decreased the atherosclerosis-associated biomarker E selectin/SELE.

CONCLUSIONS

In patients with moderate-to-severe AD, ASN002 showed strong efficacy with rapid onset of action and associated improvements in systemic inflammation.

The new entries in the therapeutic armamentarium: The small molecule JAK inhibitors

The past decade has witnessed an explosion in trial data on JAK inhibitors (JAKi). These small molecules target the Janus kinase - signal transducer and activator of transcription (JAK-STAT) pathway, blocking crucial cytokines across a septum of rheumatic diseases. As a class, JAKi are beginning to demonstrate efficacy on par, if not superior to biologics. Two first generation JAKi are licensed for use in inflammatory arthritis; tofacitinib and baricitinib. Next-generation JAKi have been designed with selective affinity for one JAK enzymes, the aim to reduce unwanted adverse effects without declining clinical efficacy. Emerging data with selective JAK1 inhibitors upadacitinib and filgotinib looks very promising. Despite differences in selectivity between JAKi, an overlap exists in their safety profiles. Across the class, a characteristic safety signal is emerging with viral opportunistic infections, particularly herpes zoster. Post marketing drug surveillance will be essential in evaluating the long-term risk with these agents.

Characterization of the Effect of Hepatic Impairment on Upadacitinib Pharmacokinetics

Upadacitinib is a selective Janus kinase 1 inhibitor being developed for the treatment of several inflammatory autoimmune diseases, including rheumatoid arthritis. Upadacitinib is a nonsensitive substrate for metabolism by cytochrome P450 3A enzymes. This open-label, single-dose, multicenter study assessed the pharmacokinetics of upadacitinib following oral administration of a single 15-mg dose of the upadacitinib extended-release formulation in subjects with mild (n = 6) and moderate (n = 6) hepatic impairment relative to demographically matched healthy subjects (n = 6). Subjects were assigned to 1 of the 3 groups according to the Child-Pugh classification. Relative to subjects with normal hepatic function, the ratios (90% confidence intervals) of upadacitinib area under the plasma concentration-versus-time profile from time 0 to infinity (AUCinf ) for subjects with mild and moderate hepatic impairment were 1.28 (0.91-1.79) and 1.24 (0.87-1.76), respectively. The central ratios of upadacitinib maximum observed concentration (Cmax ) were 1.04 (0.77-1.39) and 1.43 (1.05-1.95) in subjects with mild and moderate hepatic impairment, respectively, compared with subjects with normal hepatic function. No clinically significant changes in vital signs or hematology measurements were observed, and no new safety events were identified in this study. These results indicate that mild and moderate hepatic impairment has no clinically relevant effect on upadacitinib pharmacokinetics.

Exposure-Response Analyses of Upadacitinib Efficacy in Phase II Trials in Rheumatoid Arthritis and Basis for Phase III Dose Selection

The relationships between upadacitinib, an oral selective Janus kinase 1 inhibitor, plasma exposures, and its efficacy (assessed by the American College of Rheumatology 20%/50%/70% responses over time) in moderate‐to‐severe active rheumatoid arthritis (RA) were characterized using data from 574 patients, on background methotrexate and inadequate response to methotrexate or anti‐TNF therapy, from two phase II trials conducted with twice‐daily dosing of an immediate‐release formulation. The developed time‐continuous Markov models were used to simulate efficacy of once‐daily (q.d.). regimens of upadacitinib extended‐release incorporating sources of uncertainty. Upadacitinib plasma concentrations associated with 15 and 30 mg extended‐release q.d. doses were predicted to achieve that plateau of response across RA subpopulations. Results from these analyses provided the rationale that supported selection and de‐risked evaluation of upadacitinib extended‐release doses for the first time in >4,000 patients in five large phase III trials.

Population Pharmacokinetics of Upadacitinib Using the Immediate-Release and Extended-Release Formulations in Healthy Subjects and Subjects with Rheumatoid Arthritis: Analyses of Phase I-III Clinical Trials

BACKGROUND AND OBJECTIVES

Upadacitinib is a selective Janus kinase (JAK) 1 inhibitor being developed as an orally administered treatment for patients with moderate to severe rheumatoid arthritis (RA) and other autoimmune disorders. These analyses characterized the population pharmacokinetics of upadacitinib across phase I-III clinical trials using data for immediate-release (IR) and extended-release (ER) formulations.

METHODS

Pharmacokinetic data from 4170 subjects taking IR doses of 1-48 mg and ER doses of 7.5-30 mg across 12 studies spanning phase I-III clinical trials, with a total of 29,372 upadacitinib plasma concentrations, were analyzed using non-linear mixed-effects modeling. The model was evaluated using bootstrap analyses and visual predictive checks.

RESULTS

A two-compartment model with first-order absorption with lag time for the IR formulation, mixed zero- and first-order absorption with lag time for the ER formulation, and linear elimination, adequately described upadacitinib plasma concentration-time profiles. Population estimates of upadacitinib apparent oral clearance and steady-state volume of distribution in healthy volunteers for the ER formulation were 53.7 L/h and 294 L, respectively. The relative bioavailability of the ER formulation compared with the IR formulation was estimated to be 76.2%. Statistically significant covariates were patient population (RA subjects vs. healthy subjects), creatinine clearance, and baseline bodyweight on apparent clearance (CL/F) and bodyweight on volume of distribution of the central compartment (Vc/F). The intersubject variability for upadacitinib CL/F and Vc/F were estimated to be 21% and 24%, respectively, in the phase I studies, and 37% and 53%, respectively, in the phase II/III studies. Upadacitinib area under the concentration-time curve (AUC) was estimated to be only 5% higher or lower for RA patients who were < 60 or > 100 kg, respectively, relative to subjects with a bodyweight of 60-100 kg. RA subjects with mild or moderate renal impairment had 13% and 26% higher AUC, respectively, compared with RA subjects with normal renal function. Sex, race, concomitant use of pH-modifying drugs, moderate cytochrome P450 3A inhibitors, or methotrexate use had no effect on upadacitinib exposure.

CONCLUSIONS

A robust population pharmacokinetic model was developed for upadacitinib using a large dataset from phase I-III clinical trials in healthy volunteers and subjects with RA. None of the identified covariates had a clinically meaningful effect on upadacitinib exposures. The model is appropriate to use for simulations and to evaluate the exposure-response relationship of upadacitinib.

[Inhibition of the Janus kinase-signal transducer and activator of transcription is a new treatment modality of rheumatoid arthritis]

Rheumatoid arthritis (RA) is a chronic inflammatory joint disease. The introduction of a new class of disease-modifying anti-rheumatic drugs, which work by inhibiting the Janus kinase-signal transducer and activator of transcription (JAK/STAT) pathway, has led to new possibilities for achieving remission of RA. Tofacitinib and baricitinib are both JAK/STAT inhibitors, which have shown efficacy in line with anti-tumour necrosis factor treatment. The side effects seem manageable, and up to now only increased risk of herpes zoster has raised consideration. JAK/STAT inhibitors create new possibilities for reaching low disease activity or remission for patients with RA.

ruxolitinib (JAKAVI°) and polycythaemia vera Inconclusive evaluation

Patients with polycythaemia vera, a myeloproliferative syndrome, are at increased risk of thrombotic events. Marrow fibrosis and transformation to acute leukaemia can also occur after several years. Treatment is based on phlebotomy and aspirin at low (antiplatelet) doses, sometimes combined with hydroxycarbamide, a cytotoxic drug. Various other drugs are available if hydroxycarbamide fails or is poorly tolerated, but there is no consensus treatment. Ruxolitinib inhibits Janus tyrosine kinases, which are involved, among other roles, in haematopoiesis. Ruxolitinib has been authorised in the European Union for patients with polycythaemia vera in whom hydroxycarbamide has failed or is poorly tolerated. Clinical evaluation of ruxolitinib in this setting is based on a randomised, unblinded trial versus treatment chosen by the investigators, in 222 patients treated for 32 weeks. Hydroxycarbamide was chosen in 59% of cases, even though the patients had unacceptable adverse effects or an inadequate response to the drug. The efficacy of the investigators' other treatment choices was uncertain. Phlebotomy was less frequent in the ruxofitinib group than in the control group. The adverse effects of ruxotitinib in this situation are poorly documented, due to inadequate long-term assessment. In the short term, ruxolitinib causes anaemia and thrombocytopenia, as well as bleeding, potentially severe infections, headache, sensory disturbances, and weight gain. It is also likely to share the serious adverse effects of other immunosuppressants. Ruxolitinib is mainly metabolised by cytochrome P450 isoenzymes CYP3A4 and CYP2C9, creating a risk of multiple drug interactions. Ruxolitinib showed embryofetal toxicity in animal studies. Virtually no data are available in pregnant women. In practice, available data on the harm-benefit balance of ruxolitinib fail to show that this drug represents a tangible advance for patients with polycythaemia vera, as compared with other drugs used when hydroxycarbamide is unsuitable.