After 25 years of drug development, do we know JAK?

Janus kinase inhibitors in atopic dermatitis: an umbrella review of meta-analyses

Background

Clinicians and healthcare policymakers have been drenched with a deluge of overlapping meta-analyses (MAs), and the necessity for comprehensive and clearly defined evidence of Janus kinase inhibitors (JKIs) in atopic dermatitis (AD) is urgent.

Methods

Six databases were searched for MAs published until October 2023. Qualitative description of MAs was mainly used, and Investigator's Global Assessment response (IGA response), the 75% improvement in Eczema Area and Severity Index (the EASI75), peak pruritus Numerical rating score (PP-NRS), and adverse effects were cited to describe the efficacy and safety of JKIs. The methodological quality of the included MAs was assessed by A Measurement Tool to Assess Systematic Reviews II (AMSTAR II), and the quality of evidence was evaluated by the grading of recommendations, assessment, development, and evaluation (GRADE).

Results

Sixteen MAs were pooled in this review, of which five studies appraised JKIs, five appraised systemic JKIs, five papers assessed abrocitinib only, and one assessed baricitinib. Two studies were of "high" methodological quality and 14 MAs were of "moderate" quality. Eleven MAs integrated the results of JKIs and reported that JKIs provide faster onset of IGA response (RR=2.83, 95% CI [2.25, 3.56], high-quality evidence). Similarly, 10 MAs showed that JAK inhibitors were more effective in improving the EASI75 (RR=2.84, 95% CI [2.2, 3.67], high-quality evidence). Results from 12 MAs showed JKIs were active in reducing the PP-NRS (SMD=-0.49, 95% CI [-0.67, -0.32]). All MAs affirmed JKIs added no adverse effects leading to discontinuation and serious adverse events (P<0.05). However, 200mg of abrocitinib had a higher risk of acne (RR=4.34, 95% CI [1.61, 11.71), herpes zoster (RR=1.64, 95% CI [0.42, 6.39]), headache (RR=1.76, 95% CI [1.03, 3]), and nausea (RR=7.81, 95% CI [3.84, 15.87]). Upadacitinib was known to increase acne (RR=6.23, 95% CI [4.08, 9.49]), nasopharyngitis (RR=1.36, 95% CI [1.03, 1.8]) and blood creatine phosphokinase (blood CPK) (RR=2.41, 95% CI [1.47, 3.95]). Baricitinib at 2mg was associated with increased blood CPK (RR=2.25, 95% CI [1.1, 2.97]).

Conclusion

Compared to placebo or dupilumab, the administration of JKIs can ameliorate IGA response more effectively, improve the EASI75, and relieve pruritus without severe adverse effect, while accompanied by more acne, nasopharyngitis, headache, and digestive disturbances. The curative effect of 200 mg of abrocitinib is significant and more caution should be given in patients with gastrointestinal dysfunction, herpes zoster, and those who are acne-prone. Baricitinib and upadacitinib should be avoided in populations at high risk for cardiovascular events.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=369369, PROSPERO (CRD42022369369).

Persistence of Janus-kinase (JAK) inhibitors in rheumatoid arthritis: Australia wide study

BACKGROUND

To compare persistence of disease-modifying antirheumatic (DMARDs), with a focus on Janus kinase (JAK) inhibitors in Australian rheumatoid arthritis (RA) patients.

METHODS

A retrospective observational study was conducted among 4,521 RA patients (females n=3,181 [70.4%]), using data from the Services Australia 10% Pharmaceuticals Benefits Scheme (PBS) dataset, aged ≥18 years and initiating a DMARD between 2011 to 2021. Kaplan-Meier analysis was used to estimate persistence rates, defined as occurrence of 6 months gap after the end of a drug dispensing.

RESULTS

Twelve-month persistence rates were 72% for upadacitinib, 61% for baricitinib, 58% for subcutaneous tumor necrosis factor-alpha inhibitors (TNFi), 55% for tocilizumab, 53% for tofacitinib, and 49% for abatacept. Median treatment persistence was not reached for upadacitinib (n=574) and baricitinib (n=553); and was 15.0 months for tofacitinib (95% CI 13.5-19.5), 20.5 months for TNFi (95% CI 19.0-22.4), 19.1 months for tocilizumab (95% CI 17.9-23.6), and 12.5 months for abatacept (95% CI 10.4-14.9). Persistence rates on first-line JAK inhibitors were 68% for upadacitinib and baricitinib and 55% for tofacitinib, and 49% for TNFi, 55% for abatacept, and 57% for tocilizumab; rates were sustained for upadacitinib, TNFi, and tocilizumab but dropped to 59% for baricitinib and 47% for abatacept in the second-line treatment. For each b/tsDMARD, persistence rates were higher when combined with methotrexate or other conventional synthetic DMARDs. The median oral glucocorticoid dose decreased from 4.3 mg/day (range:0-40) to 2.3 mg/day (range:0-22) over 2 years. Changes were significant for all RA DMARDs, tofacitinib and baricitinib combined (1-2 years post initiation only), TNFi, abatacept, and tocilizumab.

CONCLUSIONS

In a real-world setting, we showed highest persistence rates on upadacitinib, followed by baricitinib and then TNFi therapy and was improved by co-therapy. All agents appeared to be corticosteroid sparing.

Managing Cardiovascular and Cancer Risk Associated with JAK Inhibitors

Janus kinase inhibitors (JAKi) have enormous appeal as immune-modulating therapies across many chronic inflammatory diseases, but recently this promise has been overshadowed by questions regarding associated cardiovascular and cancer risk emerging from the ORAL Surveillance phase 3b/4 post-marketing requirement randomized controlled trial. In that study of patients with rheumatoid arthritis with existing cardiovascular risk, tofacitinib, the first JAKi registered for chronic inflammatory disease, failed to meet non-inferiority thresholds when compared with tumor necrosis factor inhibitors for both incident major adverse cardiovascular events and incident cancer. While this result was unexpected by many, subsequently published observational data have also supported this finding. Notably, however, such a risk has largely not yet been demonstrated in patients outside the specific clinical situation examined in the trial, even in the face of many studies examining this. Nevertheless, this signal has practically re-aligned approaches to both tofacitinib and other JAKi to varying extents, in other patient populations and contexts: within rheumatoid arthritis, but also in psoriatic arthritis, axial spondyloarthritis, inflammatory bowel disease, atopic dermatitis, and beyond. Application to individual patients can be more challenging but remains important to harness the substantive potential of JAKi to the maximum extent safely possible. This review not only explores the evolution of the regulatory response to the signal, its informing data, biological plausibility, and its impact on guidelines, but also the many factors that clinicians must consider in navigating cardiovascular and cancer risk for their patients considering JAKi as immune-modulating therapy.

Therapeutic implications of current Janus kinase inhibitors as anti-COVID agents: A review

Severe cases of COVID-19 are characterized by hyperinflammation induced by cytokine storm, ARDS leading to multiorgan failure and death. JAK-STAT signaling has been implicated in immunopathogenesis of COVID-19 infection under different stages such as viral entry, escaping innate immunity, replication, and subsequent inflammatory processes. Prompted by this fact and prior utilization as an immunomodulatory agent for several autoimmune, allergic, and inflammatory conditions, Jakinibs have been recognized as validated small molecules targeting the rapid release of proinflammatory cytokines, primarily IL-6, and GM-CSF. Various clinical trials are under investigation to evaluate Jakinibs as potential candidates for treating COVID-19. Till date, there is only one small molecule Jakinib known as baricitinib has received FDA-approval as a standalone immunomodulatory agent in treating critical COVID-19 patients. Though various meta-analyses have confirmed and validated the safety and efficacy of Jakinibs, further studies are required to understand the elaborated pathogenesis of COVID-19, duration of Jakinib treatment, and assess the combination therapeutic strategies. In this review, we highlighted JAK-STAT signalling in the pathogenesis of COVID-19 and clinically approved Jakinibs. Moreover, this review described substantially the promising use of Jakinibs and discussed their limitations in the context of COVID-19 therapy. Hence, this review article provides a concise, yet significant insight into the therapeutic implications of Jakinibs as potential anti-COVID agents which opens up a new horizon in the treatment of COVID-19, effectively.

Optimization of Pyrimidine Compounds as Potent JAK1 Inhibitors and the Discovery of R507 as a Clinical Candidate

Janus kinases (JAK) play a critical role in JAK/signal transducer and activator of transcription (STAT) signaling pathways that mediate immune response and cell growth. From high-throughput screening (HTS) hit to lead optimization, a series of pyrimidine compounds has been discovered as potent JAK1 inhibitors with selectivity over JAK2. Cell-based assays were used as primary screening methods for evaluating potency and selectivity, the results were further assessed and confirmed by biochemical and additional cellular assays for lead molecules. Also discussed is the unique correlation between a trifluomethyl group and CYP3A4 inhibition in the presence of NADPH, the activity of which was successfully decreased with the reduction of fluoro-atoms, increasing IC50 from 0.5 μM to >10 μM. The development of novel and scalable synthetic routes for amino-phenyl intermediates was essential for the discovery of late-stage lead molecules, including clinical candidate R507 (33). In preclinical studies, 33 exhibited great efficacy in mouse studies by inhibiting IFNγ expression induced by IL-2 and in a rat collagen-induced arthritis disease model.