Early phase studies of JAK1 selective inhibitors in rheumatoid arthritis

Revisiting Structure-activity Relationships: Unleashing the potential of selective Janus kinase 1 inhibitors

Janus kinases (JAKs), a kind of non-receptor tyrosine kinases, the function has been implicated in the regulation of cell proliferation, differentiation and apoptosis, immune, inflammatory response and malignancies. Among them, JAK1 represents an essential target for modulating cytokines involved in inflammation and immune function. Rheumatoid arthritis, atopic dermatitis, ulcerative colitis and psoriatic arthritis are areas where approved JAK1 drugs have been applied for the treatment. In the review, we provided a brief introduction to JAK1 inhibitors in market and clinical trials. The structures of high active JAK1 compounds (IC50 ≤ 0.1 nM) were highlighted, with primary focus on structure-activity relationship and selectivity. Moreover, the druggability processes of approved drugs and high active compounds were analyzed. In addition, the issues involved in JAK1 compounds clinical application as well as strategies to surmount these challenges, were discussed.

PERFECTRA: a pragmatic, multicentre, real-life study comparing treat-to-target strategies with baricitinib versus TNF inhibitors in patients with active rheumatoid arthritis after failure on csDMARDs

OBJECTIVE

To compare the effectiveness of a strategy administering baricitinib versus one using TNF-inhibitors (TNFi) in patients with rheumatoid arthritis (RA) after conventional synthetic disease-modifying antirheumatic drugs (csDMARDs) failure in a real-life treat-to-target (T2T) setting.

METHODS

Patients with biological and targeted synthetic DMARD (b/tsDMARD) naïve RA with disease duration ≤5 years without contraindications to b/tsDMARD were randomised to either TNFi or baricitinib when csDMARD failed to achieve disease control in a T2T setting. Changes in clinical and patient-reported outcome measures (PROMs) were assessed at 12-week intervals for 48 weeks. The primary endpoint was non-inferiority, with testing for superiority if non-inferiority is demonstrated, of baricitinib strategy in the number of patients achieving American College of Rheumatology 50 (ACR50) response at 12 weeks. Secondary endpoints included 28-joint count Disease Activity Score with C reactive protein (DAS28-CRP) <2.6, changes in PROMs and radiographic progression.

RESULTS

A total of 199 patients (TNFi, n=102; baricitinib, n=97) were studied. Both study groups were similar. Baricitinib was both non-inferior and superior in achieving ACR50 response at week 12 (42% vs 20%). Moreover, 75% of baricitinib patients achieved DAS28-CRP <2.6 at week 12 compared with 46% of TNFi patients. On secondary outcomes throughout the duration of the study, the baricitinib strategy demonstrated comparable or better outcomes than TNFi strategy. Although not powered for safety, no unexpected safety signals were seen in this relatively small group of patients.

CONCLUSION

Up to present, in a T2T setting, patients with RA failing csDMARDs have two main strategies to consider, Janus Kinases inhibitor versus bDMARDs (in clinical practice, predominantly TNFi). The PERFECTRA study suggested that starting with baricitinib was superior over TNFi in achieving response at 12 weeks and resulted in improved outcomes across all studied clinical measures and PROMs throughout the study duration in these patients.

Population pharmacokinetic/pharmacodynamic modeling of H018, a selective JAK1 inhibitor, in healthy Chinese volunteers

H018 is an orally administered, selective, small-molecule inhibitor of Janus kinase 1 (JAK1) made for the treatment of rheumatoid arthritis. A population pharmacokinetic/pharmacodynamic analysis was conducted to characterize the pharmacokinetic and pharmacodynamic profile of H018 and its active metabolite using data from 48 healthy Chinese volunteers who received a single dose of 10-160 mg of H018 in a phase I clinical study. A two-compartment model with delayed absorption and linear elimination adequately described the pharmacokinetic data of H018. The apparent clearance of H018 was estimated to be 39.0 L/h, and triglyceride was identified as a covariate on it. Pharmacokinetic data of the active metabolite could be well described by a two-compartment model with linear elimination. The exposure-effect relationships in terms of pSTAT1 inhibition were well described by a direct response model, with exposure captured by an active moiety that consisted of H018 and its metabolite, weighted by the ratio of in vitro JAK1 inhibitory activity (1.13). The estimated EC50 value for the active moiety is 601 nM. In the simulation using the final model, the inhibitory effect appeared to have reached a plateau in the high-dose groups, with max inhibition rates of 81.42 %, 88.42 %, and 91.89 % for 80, 120, and 160 mg dose groups, respectively. Taken together, this study will provide an instructive reference of dose selection for subsequent clinical trials.

Complete remission of two canine cases with precursor-targeted immune-mediated anemia after combination therapy with prednisolone, cyclosporine, and oclacitinib

Background

Precursor-targeted immune-mediated anemia (PIMA) has been described in dogs presenting with nonregenerative anemia and evidence of ineffective erythropoiesis. Although it has been suggested that its occurrence may be related to the immune targeting of erythroid precursors, this pathogenesis has not been established. PIMA is mainly treated with glucocorticoids, and in cases where glucocorticoids alone are not effective, immunosuppressants are also used as combination therapy. However, not all cases of PIMA go into remission after these treatments.

Case Description

Two dogs with severe nonregenerative anemia diagnosed as PIMA based on the results of clinical pathological examinations, including bone marrow examination, were treated with whole-blood transfusion and immunosuppressive doses of prednisolone, mycophenolate mofetil, and cyclosporine. However, these treatments failed to achieve remission of PIMA. Therefore, concomitant administration of oclacitinib, which is a Janus kinase-1 inhibitor that has been applied recently to the treatment of immune-mediated diseases, was performed; this combined regimen improved the anemia and achieved complete remission of PIMA.

Conclusion

Oclacitinib may be an option for the treatment of PIMA in dogs failing to achieve remission with conventional immunosuppressive therapy.

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.

Januskinase-Inhibitoren: Next-Generation-Therapie der Uveitis

Viele PatientInnen mit visusgefährdender nicht infektiöser Uveitis bedürfen, um eine Remission ihrer Uveitis zu erreichen, einer Behandlung mit DMARDs. Obwohl herkömmliche DMARD-Therapien in einem großen Teil dieser PatientInnen eine hochpotente Therapie darstellen, ist in einzelnen Fällen aufgrund eines unzureichenden Ansprechens oder unerwünschter Wirkungen ein Therapiewechsel erforderlich. Januskinase-Inhibitoren (JAKI) sind in der Rheumatologie, Gastroenterologie und Dermatologie bereits für mehrere autoimmune Erkrankungen zugelassen. Nun steht ein Zulassungsprozess für ausgewählte Uveitisentitäten an. Wirkmechanismus: JAKI üben ihre Wirkung über die Hemmung der Phosphorylierung von Transmembranproteinen, den Januskinasen aus. Dies führt zu einer fehlenden Aktivierung von Transkriptionsfaktoren und damit zur verminderten Zytokinexpression und Entzündungshemmung. JAKI stellen in der Rheumatologie, Gastroenterologie und Dermatologie einen äußerst effektiven neuen therapeutischen Ansatz dar. Sie sind zur Behandlung bei rheumatoider Arthritis, Psoriasis-Arthritis, ankylosierender Spondylitis, Colitis ulcerosa und dem atopischen Ekzem bereits zugelassen. In bisherigen Vergleichsstudien zu etablierten Biologika konnte teilweise ein besseres therapeutisches Ansprechen beschrieben werden. Aus publizierten Fallberichten wurde auch bei Uveitispatienten, die auf klassische und biologische DMARDs unzureichend ansprachen, eine Kortisoneinsparung und Reizfreiheit erzielt. Zulassungsstudien bei JIA-assoziierter und ANA-positiver anteriorer Uveitis sind im Prozess. Zusammenfassend stellen JAKI eine innovative Therapieoption bei Patienten mit nicht infektiöser Uveitis dar, bei denen Kontraindikationen gegen die Verwendung oder ein unzureichender Effekt von DMARDs bestehen.

Quantification of the janus kinase 1 inhibitor upadacitinib in human plasma by LC-MS/MS

Upadacitinib is a selective janus-kinase-1 inhibitor effective in the treatment of autoimmune related diseases like rheumatoid arthritis or psoriatic arthritis. Here, we described a LC-MS/MS method for the quantification of upadacitinib in human plasma applicable for therapeutic drug monitoring. Pexidartinib was used as internal standard. Plasma samples were prepared by acidic protein precipitation and the analytes were separated on a C-18 reversed phase column. Detection took place by tandem mass spectroscopy after ionization in the positive mode and collision induced fragmentation at m/z 381 → 256, 213 for upadacitinib and m/z 418 → 258, 165 for pexidartinib. The calibration function was linear in the range of 0.15 - 150 ng/mL. Precisions and accuracies were better than 10% in intra- as well as inter-day evaluations. The method was applied in therapeutic drug monitoring of patients undergoing treatment for rheumatoid arthritis with the standard dose of 15 mg upadacitinib extended release formulation once daily. At steady state, we found trough levels of 4.13 (3.51 - 11.0) ng/mL, which is comparable to values found in healthy volunteers receiving the same dose (2.8 ± 1.2 ng/mL).

The role of upadacitinib in the treatment of moderate-to-severe active rheumatoid arthritis

Despite recent promising developments in the treatment of rheumatoid arthritis (RA), a substantial proportion of patients still cannot achieve the treatment targets: low disease activity and remission. Janus kinase (JAK) inhibitors have the potential to fill this important gap with their high efficiency, rapid onset of action, and acceptable safety profile. The fact that the previously approved two JAK inhibitors, tofacitinib and baricitinib, inhibit more than one JAK molecule raised the question whether a safer profile can be possible by inhibiting fewer JAK molecules. Upadacitinib, a JAK 1 selective molecule developed in this context has been evaluated in the SELECT phase-III study program and demonstrated a high and rapid efficacy in monotherapy as well as in combination with csDMARDs both in csDMARD-naive RA patients and in patients refractory to csDMARD and bDMARD treatments. Upadacitinib 15 mg once daily displayed a similar safety profile except for increased creatine phosphokinase (CPK) levels and herpes zoster (HZ) risk compared to its active comparators methotrexate (MTX) and adalimumab. Most of the CPK elevations were asymptomatic, and most of the HZ cases were not serious. Along with the randomized-controlled studies and meta-analysis results, upadacitinib 15 mg once daily has a favorable efficacy/safety profile. Long-term extensions of current studies and real-world data will be important to fully appreciate its potential in the treatment of RA.

The role for JAK inhibitors in the treatment of immune-mediated rheumatic and related conditions

JAK inhibitors (JAKIs) are a new class of targeted therapy that have entered clinical practice for the treatment of immune-mediated rheumatic conditions. JAKIs can block the signaling activity of a variety of proinflammatory cytokines and therefore have the potential to mediate therapeutic benefits across a wide range of immune-mediated conditions. Several JAKIs are licensed, and many more are undergoing clinical trials. Here we provide a narrative review of the current and upcoming JAKIs for adult immune-mediated rheumatic and related conditions, with a specific focus on efficacy in rheumatoid arthritis, psoriatic arthritis, axial spondyloarthritis, psoriasis, and inflammatory bowel disease. The overall safety profile of JAKIs appears largely comparable to that of existing biologic cytokine-targeting agents, particularly, TNF inhibitors, apart from risk of herpes zoster, which is increased for JAKIs. Importantly however, unresolved safety concerns remain, particularly relating to increased venous thromboembolism.