Discovery of Clinical Candidate GLPG3970: A Potent and Selective Dual SIK2/SIK3 Inhibitor for the Treatment of Autoimmune and Inflammatory Diseases

Discovery of Novel SIK2/3 Inhibitors for the Potential Treatment of MEF2C+ Acute Myeloid Leukemia (AML)

The dual inhibition of SIK2/3 has been considered as a potential treatment approach for MEF2C-high acute myeloid leukemia (AML). Although diverse scaffolds of pan-SIK or SIK2/3 inhibitors have been reported, few of them showed sufficient in vitro or in vivo antitumor activity. Based on the proposed binding mode of the hit molecule (7), chemical space in the solvent/P-loop region was explored via fragment growing/replacement, supported by the generative chemistry platform. Further SAR exploration and ADME optimization led to the discovery of 7s, which exhibited excellent potency and strong selectivity in MEF2C high-expression cell lines over MEF2C-low cell lines. Moreover, oral administration of 7s was found to demonstrate significant tumor growth inhibition in a MV4-11 AML mice CDX model without any body weight loss. This work highlights the potential of targeting MEF2C-dependent AML by selective oral SIK2/3 inhibitors, which was supported by the generative models.

Inhibition of SIK1 Alleviates the Pathologies of Psoriasis by Disrupting IL-17 Signaling

Psoriasis is an inflammatory skin disease mediated by multiple immune cells, including T cells, macrophages, and dendritic cells, which exhibit complex pathologies and limited clinical treatment. Here, we found that salt-inducible kinase 1 (SIK1) was upregulated in the imiquimod (IMQ)-induced psoriasis mouse model. This increment may be due to a higher level of interleukin-17, which promoted the expression of SIK1 in keratinocytes. Inhibition of SIK1 kinase activity using a small molecular inhibitor (HG-9-91-01 or YKL-06-062) dramatically alleviated IMQ-induced psoriasis, showing reduced epidermal thickness, inflammation, and hyperproliferative epidermal keratinocytes. Our data demonstrated that SIK1 inhibitors HG-9-91-01 or YKL-06-062 blocked the expression of IL-17-induced proinflammatory cytokines and chemokines, including Il6, Kc, and Ccl20. Mechanistically, we found that SIK1 inhibitor HG-9-91-01 or YKL-06-062 suppressed the phosphorylation of Iκbα and P38. Consistently, SIK1 overexpression in keratinocytes promoted the activation of Iκbα and P38. Collectively, our results reveal that SIK1 participates to promote IL17-induced signaling through enhancing activation of NF-κB and MAPKs and exacerbates psoriasis-like skin inflammation. Thus, inhibition of SIK1 presents a potential new therapeutic target for psoriasis.

Central and Peripheral Roles of Salt-inducible Kinases in Metabolic Regulation

Salt-inducible kinases (SIKs), a member of the serine/threonine protein kinase family, have recently garnered considerable research interest as one of the emerging key regulators of metabolism. The 3 SIK isoforms-SIK1, SIK2, and SIK3-exhibit diverse roles both in central and peripheral physiological processes. While early studies focused on their role in inflammation, spurring the development of SIK inhibitors for chronic inflammatory diseases currently in clinical trials, emerging evidence highlights their broader functions in metabolism. In this review, we will summarize the current state of research on the central roles of SIKs in the brain, particularly in regulating energy balance and glucose homeostasis, alongside their peripheral functions in critical metabolic tissues such as the liver, adipose tissue, and pancreas. By integrating insights into their central and peripheral roles, this review underscores the importance of SIKs in maintaining metabolic homeostasis and highlights their therapeutic potential as novel targets for metabolic disease.

Effects of GLPG3970 on Sulfasalazine and Methotrexate Pharmacokinetics in Healthy Adults: Two Open-Label, Phase I, Drug-Drug Interaction Studies

GLPG3970 is a selective salt-inducible kinase 2/3 inhibitor intended for the treatment of inflammatory diseases. In vitro studies suggest GLPG3970 strongly inhibits breast cancer resistance protein (BCRP), indicating a possible interaction with BCRP substrates such as sulfasalazine (SSZ; a probe substrate for intestinal BCRP inhibition) and methotrexate (MTX), both inflammatory disease medications. Two open-label, nonrandomized, phase I, drug-drug interaction (DDI) studies assessed the pharmacokinetics of SSZ 1,000 mg (NCT04720183) and MTX 7.5 mg (EudraCT: 2020-000391-37) with and without GLPG3970 350 mg. Healthy participants aged 18-55 years with wild-type homozygous BCRP genotype (c421C/C) received: SSZ on day (D)1, GLPG3970 + SSZ on D5, and GLPG3970 2 hours after SSZ on D9 (N = 8; SSZ/GLPG3970 DDI study); MTX on D1, GLPG3970 + MTX on D5, and GLPG3970 on D6-8 (N = 15; MTX/GLPG3970 DDI study). Primary end points were AUC and Cmax ("exposure") of SSZ and its metabolite (sulfapyridine [SPD]), SPD:SSZ AUC ratio (SSZ/GLPG3970 study), and AUC and Cmax ("exposure") of MTX (MTX/GLPG3970 study). DDIs were evaluated using the geometric mean ratio of each end point; a > 2-fold increase in SSZ or MTX exposure was deemed clinically relevant. GLPG3970 demonstrated mild inhibition of intestinal BCRP in vivo: GLPG3970 + SSZ increased SSZ exposure ~1.7-1.8-fold and decreased SPD:SSZ ratio ~ 2-fold vs. SSZ alone. GLPG3970 administered 2 hours after SSZ did not change the magnitude of the interaction. GLPG3970 + MTX had no relevant effect on MTX pharmacokinetics vs. MTX alone. Therefore, the strong in vitro BCRP inhibition was not confirmed in vivo. No safety concerns were observed when GLPG3970 was coadministered with SSZ or MTX.

Manual Therapy Improves Fibromyalgia Symptoms by Downregulating SIK1

Fibromyalgia (FM), classified by ICD-11 with code MG30.0, is a chronic debilitating disease characterized by widespread pain, fatigue, cognitive impairment, sleep, and intestinal alterations, among others. FM affects a large proportion of the worldwide population, with increased prevalence among women. The lack of understanding of its etiology and pathophysiology hampers the development of effective treatments. Our group had developed a manual therapy (MT) pressure-controlled custom manual protocol on FM showing hyperalgesia/allodynia, fatigue, and patient's quality of life benefits in a cohort of 38 FM cases (NCT04174300). With the aim of understanding the therapeutic molecular mechanisms triggered by MT, this study interrogated Peripheral Blood Mononuclear Cell (PBMC) transcriptomes from FM participants in this clinical trial using whole RNA sequencing (RNAseq) and reverse transcription followed by quantitative Polymerase Chain Reaction (RT-qPCR) technologies. The results show that the salt-induced kinase SIK1 gene was consistently downregulated by MT in FM, correlating with improvement of patient symptoms. In addition, this study compared the findings in a non-FM control cohort subjected to the same MT protocol, evidencing that those changes in SIK1 expression with MT only occurred in individuals with FM. This positions SIK1 as a potential biomarker to monitor response to MT and as a therapeutic target of FM, which will be further explored by continuation studies.

Understanding the roles of salt-inducible kinases in cardiometabolic disease

Salt-inducible kinases (SIKs) are serine/threonine kinases of the adenosine monophosphate-activated protein kinase family. Acting as mediators of a broad array of neuronal and hormonal signaling pathways, SIKs play diverse roles in many physiological and pathological processes. Phosphorylation by the upstream kinase liver kinase B1 is required for SIK activation, while phosphorylation by protein kinase A induces the binding of 14-3-3 protein and leads to SIK inhibition. SIKs are subjected to auto-phosphorylation regulation and their activity can also be modulated by Ca2+/calmodulin-dependent protein kinase in response to cellular calcium influx. SIKs regulate the physiological processes through direct phosphorylation on various substrates, which include class IIa histone deacetylases, cAMP-regulated transcriptional coactivators, phosphatase methylesterase-1, among others. Accumulative body of studies have demonstrated that SIKs are important regulators of the cardiovascular system, including early works establishing their roles in sodium sensing and vascular homeostasis and recent progress in pulmonary arterial hypertension and pathological cardiac remodeling. SIKs also regulate inflammation, fibrosis, and metabolic homeostasis, which are essential pathological underpinnings of cardiovascular disease. The development of small molecule SIK inhibitors provides the translational opportunity to explore their potential as therapeutic targets for treating cardiometabolic disease in the future.