The Selective JAK1/3-Inhibitor R507 Mitigates Obliterative Airway Disease Both With Systemic Administration and Aerosol Inhalation

JAK inhibitor selectivity: new opportunities, better drugs?

Cytokines function as communication tools of the immune system, serving critical functions in many biological responses and shaping the immune response. When cytokine production or their biological activity goes awry, the homeostatic balance of the immune response is altered, leading to the development of several pathologies such as autoimmune and inflammatory disorders. Cytokines bind to specific receptors on cells, triggering the activation of intracellular enzymes known as Janus kinases (JAKs). The JAK family comprises four members, JAK1, JAK2, JAK3 and tyrosine kinase 2, which are critical for intracellular cytokine signalling. Since the mid-2010s multiple JAK inhibitors have been approved for inflammatory and haematological indications. Currently, approved JAK inhibitors have demonstrated clinical efficacy; however, improved selectivity for specific JAKs is likely to enhance safety profiles, and different strategies have been used to accomplish enhanced JAK selectivity. In this update, we discuss the background of JAK inhibitors, current approved indications and adverse effects, along with new developments in this field. We address the issue of JAK selectivity and its relevance in terms of efficacy, and describe new modalities of JAK targeting, as well as new aspects of JAK inhibitor action.

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.

Clinical efficacy of montelukast sodium combined with budesonide or combined with loratadine in treating children with cough variant asthma and influence on inflammatory factors in the serum

Clinical efficacy of montelukast sodium combined with budesonide or combined with loratadine in children with cough variant asthma was investigated. A retrospective analysis of the medical records of 72 children with cough variant asthma who were treated in Xuzhou Children's Hospital, Xuzhou Medical University from April 2015 to August 2017 was performed and the 72 child patients were divided into two groups: 35 children were treated with montelukast sodium combined with budesonide in Group A, and 37 children were treated with montelukast sodium combined with loratadine in Group B. The clinical efficacy of the two groups was evaluated according to the lung function indexes [forced expiratory volume in the first second (FEV1), ratio of the forced expiratory volume in the first second to the forced vital capacity (FEV1/FVC), the peak expiratory flow (PEF)], the inflammation biomarkers [tumor necrosis factor-α (TNF-α) and interleukin-4 (IL-4)], the level of eosinophil granulocyte, and the level of IgE at three time-points: before treatment, the 4th week after treatment, and the 12th week after treatment as well as adverse reactions, recurrence of symptoms, and treatment compliance were recorded. After treatment, the levels of FEV1, FEV1/FVC, PEF, TNF-α and IL-4, eosinophil granulocyte and IgE in the two groups were significantly improved (P<0.05). The treatment compliance of Group A was significantly lower than that of Group B (P<0.05). In conclusion, the method of montelukast sodium combined with budesonide or loratadine are both worthy of clinical promotion because they have equivalent efficacy in the treatment of cough variant asthma to effectively improve the lung function and inflammatory response in patients and both bring less adverse reactions and lower recurrence rate.

Tofacitinib Halts Progression of Graft Dysfunction in a Rat Model of Mixed Cellular and Humoral Rejection

BACKGROUND

The progression from acute to chronic antibody-mediated rejection in kidney transplant recipients is usually not prevented by current therapeutic options. Here, we investigated whether the use of tofacitinib (TOFA), a Janus kinase 3 inhibitor, was capable of preventing the progression of allograft dysfunction in a Fisher-to-Lewis rat model of kidney transplantation.

METHODS

Rats were treated from the third week after transplantation to allow the development of rejection. Treatment was based on cyclosporin A, rapamycin or TOFA. Renal function was assessed at 1, 4, 8, and 12 weeks after transplantation, whereas rat survival, histological lesions, and infiltrating lymphocytes were analyzed at 12 weeks.

RESULTS

Tofacitinib prolonged graft survival, preserved tubular and glomerular structures and reduced humoral damage characterized by C4d deposition. Tofacitinib was able to reduce donor-specific antibodies. In addition, T and natural killer cell graft infiltration was reduced in TOFA-treated rats. Although rapamycin-treated rats also showed prolonged graft survival, glomerular structures were more affected. Moreover, only TOFA treatment reduced the presence of T, B and natural killer cells in splenic parenchyma.

CONCLUSIONS

Tofacitinib is able to reduce the immune response generated in a rat model of kidney graft rejection, providing prolonged graft and recipient survival, better graft function, and less histological lesions.