Discovery of diaminopyrimidine-carboxamide derivatives as JAK3 inhibitors

Structural optimizations on the 7H-pyrrolo[2,3-d]pyrimidine scaffold to develop highly selective, safe and potent JAK3 inhibitors for the treatment of Rheumatoid arthritis

Janus Kinase 3 (JAK3) is important for the signaling transduction of cytokines in immune cells and is identified as potential target for treatment of rheumatoid arthritis (RA). Recently, we designed and synthesized two JAK3 inhibitors J1b and J1f, which featured with high selectivity but mild bioactivity. Therefore, in present study the structure was optimized to increase the potency. As shown in the results, most of the compounds synthesized showed stronger inhibitory activities against JAK3 in contrast to the lead compounds, among which 9a was the most promising candidate because it had the most potent effect in ameliorating carrageenan-induced inflammation of mice and exhibited low acute in vivo toxicity (MTD > 2 g/kg). Further analysis revealed that 9a was highly selective to JAK3 (IC50 = 0.29 nM) with only minimal effect on other JAK members (>3300-fold) and those kinases bearing a thiol in a position analogous to that of Cys909 in JAK3 (>150-fold). Meanwhile, the selectivity of JAK3 was also confirmed by PBMC stimulation assay, in which 9a irreversibly bound to JAK3 and robustly inhibited the signaling transduction with mild suppression on other JAKs. Moreover, it was showed that 9a could remarkably inhibited the proliferation of lymphocytes in response to concanavalin A and significantly mitigate disease severity in collagen induced arthritis. Therefore, present data indicate that compound 9a is a selective JAK3 inhibitor and could be a promising candidate for clinical treatment of RA.

ERBB1/EGFR and JAK3 Tyrosine Kinases as Potential Therapeutic Targets in High-Risk Multiple Myeloma

Our main objective was to identify abundantly expressed tyrosine kinases in multiple myeloma (MM) as potential therapeutic targets. We first compared the transcriptomes of malignant plasma cells from newly diagnosed MM patients who were risk-categorized based on the patient-specific EMC-92/SKY-92 gene expression signature values vs. normal plasma cells from healthy volunteers using archived datasets from the HOVON65/GMMG-HD4 randomized Phase 3 study evaluating the clinical efficacy of bortezomib induction/maintenance versus classic cytotoxic drugs and thalidomide maintenance. In particular, ERBB1/EGFR was significantly overexpressed in MM cells in comparison to normal control plasma cells, and it was differentially overexpressed in MM cells from high-risk patients. Amplified expression of EGFR/ERBB1 mRNA in MM cells was positively correlated with increased expression levels of mRNAs for several DNA binding proteins and transcription factors with known upregulating activity on EGFR/ERBB1 gene expression. MM patients with the highest ERBB1/EGFR expression level had significantly shorter PFS and OS times than patients with the lowest ERBB1/EGFR expression level. High expression levels of EGFR/ERBB1 were associated with significantly increased hazard ratios for unfavorable PFS and OS outcomes in both univariate and multivariate Cox proportional hazards models. The impact of high EGFR/ERBB1 expression on the PFS and OS outcomes remained significant even after accounting for the prognostic effects of other covariates. These results regarding the prognostic effect of EGFR/ERBB1 expression were validated using the MMRF-CoMMpass RNAseq dataset generated in patients treated with more recently applied drug combinations included in contemporary induction regimens. Our findings provide new insights regarding the molecular mechanism and potential clinical significance of upregulated EGFR/ERBB1 expression in MM.

Optimisation of momelotinib with improved potency and efficacy as pan-JAK inhibitor

Dysregulated JAK-STAT signaling has been proven to be involved in several immune-mediated diseases. Several janus kinase (JAK) inhibitors have been approved for the treatment of various inflammatory and autoimmune diseases such as rheumatoid arthritis (RA), plaque psoriasis, psoriatic arthritis, inflammatory bowel disease (IBD). Here, we report the design, optimisation, synthesis and biological evaluation of momelotinib analogues (a pyrimidine based JAK inhibitor), to get pan-JAK inhibitors. Systematic structure activity relationship studies led to the discovery of compound 32, which potently inhibited JAK1, JAK2 and JAK3. The in vivo investigation indicated that compound 32 possessed favourable pharmacokinetic properties and displayed superior anti-inflammatory efficacy than momelotinib 1. Accordingly, compound 32 was advanced into preclinical development.

Design, synthesis and antiproliferative activity of novel 2,4-diamino-5-methyleneaminopyrimidine derivatives as potential anticancer agents

In order to discover new anticancer agents, 25 novel 2,4-diamino-5-methyleneaminopyrimidine derivatives were designed and synthesized based on our previous work via a ring-opening strategy. Among them, compared with 5-FU, compound 7i exhibited 4.9-, 2.9-, 2.1-, and 3.0-fold improvement in inhibiting HCT116, HT-29, MCF-7, and HeLa cells proliferation with IC₅₀ values of 4.93, 5.57, 8.84, and 14.16 μM, respectively. Moreover, further mechanistic studies indicated that compound 7i could concentration-dependently induce cell cycle arrest and apoptosis in HCT116 cells. These findings revealed that 2,4-diamino-5-methyleneaminopyrimidine scaffold has potential for further investigation to explore novel anticancer agents.