Selective Sphingosine Research Articles

The Two Sides of Siponimod: Evidence for Brain and Immune Mechanisms in Multiple Sclerosis.

Siponimod is a selective sphingosine 1-phosphate receptor subtype 1 (S1P1) and 5 (S1P5) modulator approved in the United States and the European Union as an oral treatment for adults with relapsing forms of multiple sclerosis (RMS), including active secondary progressive multiple sclerosis (SPMS). Preclinical and clinical studies provide support for a dual mechanism of action of siponimod, targeting peripherally mediated inflammation and exerting direct central effects. As an S1P1 receptor modulator, siponimod reduces lymphocyte egress from lymph nodes, thus inhibiting their migration from the periphery to the central nervous system. As a result of its peripheral immunomodulatory effects, siponimod reduces both magnetic resonance imaging (MRI) lesion (gadolinium-enhancing and new/enlarging T2 hyperintense) and relapse activity compared with placebo. Independent of these effects, siponimod can penetrate the blood–brain barrier and, by binding to S1P1 and S1P5 receptors on a variety of brain cells, including astrocytes, oligodendrocytes, neurons, and microglia, exert effects to modulate neural inflammation and neurodegeneration. Clinical data in patients with SPMS have shown that, compared with placebo, siponimod treatment is associated with reductions in levels of neurofilament light chain (a marker of neuroaxonal damage) and thalamic and cortical gray matter atrophy, with smaller reductions in MRI magnetization transfer ratio and reduced confirmed disability progression. This review examines the preclinical and clinical data supporting the dual mechanism of action of siponimod in RMS.

043 Efficacy of siponimod in secondary progressive multiple sclerosis with active disease: EXPAND study subgroup analysis

BackgroundSiponimod, a selective sphingosine 1-phosphate receptor modulator, demonstrated clini- cally relevant effects in a typical secondary progressive multiple sclerosis (SPMS) population in the Phase 3 EXPAND study, with 21% and 26% reductions in 3- and 6-month confirmed disability progression (CDP) versus placebo.MethodsPost hoc subgroup analysis was performed in patients with active disease (defined as the presence of relapses in 2 years before screening and/or ≥1 T1 gadolinium-enhancing [Gd ] lesion at baseline) to assess the efficacy of siponimod 2mg versus placebo in this population.ResultsThis analysis included 779 SPMS patients with active disease (siponimod [n=516], placebo [n=263]). The proportion of patients with relapse in the 2 years prior to study was 76% and with Gd lesions at baseline 45%. Siponimod significantly reduced 3-month CDP risk by 31% (HR [95% CI]: 0.69 [0.53, 0.91]; p=0.0094) and 6-month CDP risk by 37% (HR [95% CI]: 0.63 [0.47, 0.86], p=0.0040) versus placebo. Reductions in risk of 6 month SDMT worsening, ARR, and MRI endpoints were also seen.ConclusionsIn this subgroup of active SPMS patients from EXPAND, benefits on disability progression were more pronounced with clinically relevant effects across disability progression, cognitive processing speed, and MRI inflammatory disease activity.g.giovannoni@qmul.ac.uk

In Vitro Characterization of Sphingosine 1-Phosphate Receptor 1 (S1P1) Expression and Mediated Migration of Primary Human T and B Cells in the Context of Cenerimod, a Novel, Selective S1P1 Receptor Modulator.

Cenerimod is a potent, selective sphingosine 1-phosphate receptor 1 (S1P1) modulator currently investigated in a Phase IIb study in patients with systemic lupus erythematosus (SLE) (NCT03742037). S1P1 receptor modulators sequester circulating lymphocytes within lymph nodes, thereby reducing pathogenic autoimmune cells (including T and B lymphocytes) in the bloodstream and inflamed tissues, making them an effective therapeutic concept for autoimmune disorders. Although the effect of S1P receptor modulators in reducing circulating lymphocytes is well documented, the precise molecular role of the S1P1 receptor on these cell types is not fully understood. In this study, the mode of action of cenerimod on human primary lymphocytes in different activation states was investigated focusing on their chemotactic behavior towards S1P in real-time, concomitant to S1P1 receptor expression and internalization dynamics. Here, we show that cenerimod effectively prevents T and B cell migration in a concentration-dependent manner. Interestingly, while T cell activation led to strong S1P1 re-expression and enhanced migration; in B cells, an enhanced migration capacity and S1P1 receptor surface expression was observed in an unstimulated state. Importantly, concomitant treatment with glucocorticoids (GCs), a frequently used treatment for autoimmune disorders, had no impact on the inhibitory activity of cenerimod on lymphocytes.

P562 A Phase 1 Study Evaluating the Effect of Coadministration of Etrasimod on the Pharmacokinetics and Pharmacodynamics of a Monophasic Oral Contraceptive in Healthy Female Volunteers

Abstract Background Etrasimod (ETR) is a once-daily (QD), oral, selective sphingosine 1-phosphate receptor modulator in clinical development for immune-mediated inflammatory disorders including inflammatory bowel disease (IBD) and atopic dermatitis. At diagnosis, ~50% of patients with IBD are <35 years old. Oral contraceptives (OC) are the most common birth control among women in the US. It’s important to ensure an IBD therapy does not impact the pharmacokinetic (PK)/pharmacodynamic (PD) performance of the OC. This study evaluated the effect of coadministration of ETR on the PK/PD performance of a monophasic OC. Methods This open-label Phase 1 study enrolled 21 premenopausal healthy female adults (18–40 years). On Days 1–21 of Period 1 (Days 1–28), participants received OC containing 30mcg ethinylestradiol (EE) and 50mcg levonorgestrel (LVG). On Day 23, participants initiated ETR 2mg QD such that steady-state concentrations were achieved by Day 28 and thereafter. On Days 29–49 of Period 2 (Days 29–50), the OC was coadministered with ETR 2mg QD. Samples for measuring the pharmacologically active components of the OC (EE and LVG) were collected over 24 hours on Days 21 and 49. Log-transformed primary PK parameters were calculated and compared using analysis of variance with treatment as fixed effect and participant as random effect. PD markers (follicle-stimulating hormone [FSH], luteinizing hormone [LH], estradiol, progesterone) were measured at baseline (Days 1 and 29) and throughout Periods 1 and 2. Largest ovarian follicle size measured by transvaginal ultrasound (TVUS), sex hormone–binding globulin (SHBG) levels, and Hoogland score were measured on Days 1 (before OC dosing), 11, 29 (before OC+ETR dosing), and 39. Safety and tolerability were also evaluated. Results Only minor-to-mild increases in EE and LVG Cmax,ss and AUCtau,ss exposure measures were observed when the OC was coadministered with ETR vs when the OC was administered alone (Table). These changes were not considered clinically relevant. Markers of ovarian activity (FSH, LH, estradiol, progesterone, SHBG, TVUS/Hoogland score) demonstrated no clinically relevant impact of coadministration of ETR on the PD performance of the OC. All treatments were generally well tolerated. Most treatment-emergent adverse events (AEs) were mild or moderate; 2 participants had severe AEs. No abnormalities in laboratory parameters, vital signs, or 12-lead electrocardiogram assessments were noted. Conclusion The PK/PD performance of the monophasic OC was not altered to a clinically relevant extent; thus contraceptive efficacy was maintained during coadministration with ETR. ETR and the monophasic OC, administered alone or in combination, were generally well tolerated.

OP27 A Phase 1 Study Evaluating the Bioequivalence of the Proposed Commercial and Clinical Formulations of Etrasimod 2mg, and the Effect of Food on the Pharmacokinetics of the Proposed Commercial Formulation in Healthy Volunteers

Abstract Background Etrasimod (ETR) is a once-daily, oral, selective sphingosine 1-phosphate receptor modulator in clinical development for immune-mediated inflammatory disorders including ulcerative colitis, Crohn’s disease, eosinophilic esophagitis, and atopic dermatitis. This study evaluated the single-dose bioequivalence of the proposed commercial and clinical formulations of ETR 2mg in the fasted state, and the effect of food on the pharmacokinetics of the proposed commercial formulation. Methods This 3-treatment, 3-period crossover Phase 1 study enrolled 18 healthy adults (18–55 years: 10 males/8 females). Participants were randomized to 6 treatment sequences (3 participants/sequence: ABC, BCA, CAB, ACB, BAC, CBA) consisting of Treatment A (single-dose ETR 2mg clinical formulation, fasted), Treatment B (single-dose ETR 2mg proposed commercial formulation, fasted), and Treatment C (single-dose ETR 2mg proposed commercial formulation, fed). Treatments were administered on Days 1, 10, and 19 to allow 8-day washout periods between treatments. In the fed state (Treatment C), all participants received an FDA-standard high-fat, high-calorie meal. Blood samples for determination of ETR concentration were collected at prespecified timepoints to 168 hours post dose. Analysis of variance was performed on log-transformed Cmax, AUC0-last, and AUC0-∞ values to determine geometric least squares mean ratios (GLSMR) of Test/Reference and associated 90% confidence intervals (CI) to assess bioequivalence and food effects. Safety and tolerability of ETR were also evaluated. Results Bioequivalence: The 90% CI for the GLSMR of ETR Cmax and AUC plasma exposure measures, comparing the proposed commercial vs clinical formulations, were within the accepted 80%–125% range (GLSMR and 90% CI) for establishing bioequivalence (Table 1). Median Tmax for Treatments A and B were both 4 hours. Food Effect: The 90% CI for the GLSMR of ETR Cmax and AUC plasma exposure measures, comparing the proposed commercial formulation under fed vs fasted conditions, were within the accepted 80%–125% range for establishing no food effect (Table 2). Median Tmax for Treatment C was 6 hours. Safety and Tolerability: All treatment-emergent adverse events (AEs) were mild (except 1 moderate AE [headache]). One participant had an AE leading to study drug discontinuation. There were no serious AEs or deaths. Conclusion Based on results from this study, the proposed commercial and clinical formulations of ETR 2mg were bioequivalent in terms of rate and extent of absorption. No significant differences were demonstrated in ETR exposure for the proposed commercial formulation under fed and fasted conditions. All treatments were generally safe and well tolerated.

The first russian experience of use of siponimod in real clinical practice

Despite significant success in the treatment of multiple sclerosis achieved in the recent years, the issues of therapy for progressive forms of the disease are far from being resolved. The first medication with proven efficiency at SPMS is the oral selective sphingosine 1 phosphate (S1P) receptor modulator siponimod. Before the registration of siponimod in Russia, Novartis company organized a «Managed access program to enable siponimod in patients with secondary progressive multiple sclerosis without satisfactory alternative therapy». For the period from September 2020 to May 2021, 10 patients with SPMS with exacerbations were included in the programme by RAS. The results of the treatment of the patients under the programme were similar to the results of previously controlled studies. The medication was well tolerated and the expected side effects (mainly lymphopenia and Elevated transaminases) were not more severe than moderate and were stopped by temporary cancel of the current treatment or concomitant therapy. During 1 year of therapy, the stabilization of condition of all patients and positive dynamics was noticed, including a decrease in the EDSS score in 44% of patients. Despite the limited number of patients and time of observation, the safety and efficacy of siponimod in patients with SPMS are quite high. The use of the medication in routine clinical practice does not require extraordinary methods of observation and control, but nevertheless includes genetic examination before the prescription of therapy, regular monitoring of clinical blood and biochemical parameters.

Review article: the sphingosine 1 phosphate/sphingosine 1 phosphate receptor axis - a unique therapeutic target in inflammatory bowel disease.

Ozanimod, a high selective sphingosine 1 phosphate (S1P) receptor (S1PR) 1/5 modulator was approved by the Food and Drug Administration for the treatment of adult patients with moderately to severely active ulcerative colitis. Additional S1PR modulators are being tested in clinical development programmes for both ulcerative colitis and Crohn's disease. To provide an overview of advances in understanding S1PRs biology and summarise preclinical and clinical investigations of S1P receptor modulators in chronic inflammatory disease with special emphasis on inflammatory bowel diseases (IBD). We performed a narrative review using PubMed and ClinicalTrials.gov. Through S1PRs, S1P regulates multiple cellular processes, including proliferation, migration, survival, and vascular barrier integrity. The S1PRs function of regulating lymphocyte trafficking is well known, but new functions of S1PRs expand our knowledge of S1PRs biology. Several S1PR modulators are in clinical development for both ulcerative colitis and Crohn's disease and have shown promise in phase II and III studies with ozanimod now being approved for ulcerative colitis. S1P receptor modulators constitute a novel, promising, safe, and convenient strategy for the treatment of IBD.

Pfizer to acquire biotech firm Arena for $6.7 billion

Seeking to add firepower to its efforts to develop autoimmune disease drugs, Pfizer will acquire Arena Pharmaceuticals for about $6.7 billion. Arena’s portfolio includes several development-stage drug candidates, including lead candidate etrasimod, an oral, selective sphingosine 1-phosphate receptor modulator currently in Phase 3 clinical trials for ulcerative colitis and a Phase 2/3 trial for Crohn’s disease. Analysts say the deal will boost Pfizer’s pipeline in inflammation and immunology drugs and diversify the firm beyond Janus kinase inhibitors, inflammation drugs that have come under increasing scrutiny. The US Food and Drug Administration requires new heart safety and cancer warnings for several drugs in the category, including one from Pfizer. Pfizer’s agreement to pay $100 per share for Arena, double its previous closing price, is reasonable, especially given prospects for etrasimod, according to a note from stock analysts at Mizuho Securities. The price premium is mitigated by Pfizer’s profits from the COVID-19

P029 Pharmacokinetic/Pharmacodynamic Analysis of Amiselimod, a Selective Sphingosine 1-Phosphate Receptor Modulator, in Healthy Subjects: Results From a Phase 1 Study.

Amiselimod is a selective sphingosine 1-phosphate receptor modulator in development for inflammatory bowel disease. It is converted to its active metabolite, amiselimod phosphate (amiselimod-P), and has a long half-life and slow accumulation to steady state. We evaluated a multiple-dose titration regimen to determine the plasma pharmacokinetic (PK) profile of amiselimod and amiselimod-P at steady state for the 0.4 mg QD therapeutic dose on day 13 and for the 0.8 mg QD supratherapeutic dose on day 26. We also investigated the pharmacodynamic (PD) effect of amiselimod on absolute lymphocyte counts (ALCs). A randomized, double-blind, multiple-dose, placebo-controlled, parallel study with a nested crossover design assessed amiselimod and amiselimod-P. Healthy adults received a single dose of placebo followed by oral amiselimod, which was upwardly titrated in doses ranging from 0.4 to 1.6 mg QD to rapidly achieve steady-state concentrations for the 0.4 mg QD and 0.8 mg QD doses within a 28-day treatment period. The PK parameters of amiselimod and amiselimod-P (on days 1, 13 and 26) included the geometric mean (geometric coefficient of variation percentage [CV%]) maximum plasma concentration (Cmax), median (minimum, maximum) time to Cmax (Tmax), geometric mean (geometric CV%) area under the concentration-time curve (AUC) from time 0 to the last measurable concentration, and geometric mean (geometric CV%) AUC from time 0 to 23.5 hours post dose (AUC0-23.5). Multidose PD were evaluated by changes in ALCs. The PK population included 95 amiselimod-treated participants and the PD population included 190 participants who received amiselimod or placebo. On day 13, the steady-state AUC and Cmax for amiselimod 0.4 mg QD increased by 10-fold for amiselimod and by 4-fold for amiselimod-P compared with day 1. On day 26, the steady-state AUC0-23.5 and Cmax for amiselimod 0.8 mg QD increased by 1.9-fold for amiselimod and by 1.8-fold for amiselimod-P compared with day 13. The median Tmax of plasma amiselimod and amiselimod-P were similar on all 3 days and were reached at 11 to 12 hours post dose for amiselimod and at 10 hours post dose for amiselimod-P. The mean ALCs for amiselimod exhibited a gradual decrease from pre-dose (1.681 × 103/uL) to a nadir of 0.424 × 103/uL on day 27. The abbreviated amiselimod dosing titration regimen reached steady state within 14 days for the therapeutic 0.4 mg QD regimen and within 26 days for the supratherapeutic 0.8 mg QD regimen; expected decreases in ALCs were observed following amiselimod.

Tumor progress intercept by intervening in Caveolin-1 related intercellular communication via ROS-sensitive c-Myc targeting therapy

Tumor-associated macrophages (TAMs) in the tumor microenvironment (TME) play an important role in the development of tumors by secreting a variety of cytokines or directly communicating with tumor cells, making TAMs-targeted therapeutic strategies very attractive. It has been reported that oncogene c-Myc is related to every aspect of the oncogenic process of tumor cells and the alternative activation of macrophages. Hence, we constructed a glycolipid nanocarrier containing ROS-responsive peroxalate linkages (CSOPOSA) for ROS-triggered release of drugs and further modified it with Ex 26 (Ex 26-CSOPOSA), a selective sphingosine 1-phosphate receptor 1 (S1PR1) antagonist, to achieve the dual-targeted delivery of the c-Myc inhibitor JQ1 via S1PR1, which is overexpressed on both tumor cells and TAMs, thereby inducing apoptosis of tumor cells, and blocking M2 polarization of macrophages. More strikingly, our studies found that JQ1 could effectively inhibit the migration of tumor cells induced by M2 macrophages-derived exosomes via blocking Caveolin-1 related intercellular exosome exchange through lncRNA H19 and miR-107. The in vivo results revealed that this dual-targeted delivery strategy effectively inhibited tumor growth and metastasis with less systemic toxicity, providing a potential method for effective tumor treatment.

P291 Pharmacokinetics, safety, and tolerability of etrasimod (APD334) in subjects with mild, moderate, or severe hepatic impairment: a single-dose, open-label, parallel-group study

Abstract Background Etrasimod is an oral, selective sphingosine 1-phosphate receptor modulator in clinical development for immune-mediated inflammatory disorders, including ulcerative colitis, Crohn’s disease, and eosinophilic esophagitis. The objective of this study was to evaluate the effect of hepatic impairment on the pharmacokinetics (PK), safety, and tolerability of etrasimod. Methods This single-dose, open-label, parallel-group study included 36 adult subjects (aged 18-80 years; body mass index ≥18 kg/m2) with hepatic impairment, based on Child-Pugh score at screening (mild=5 to 6 [n=8], moderate=7 to 9 [n=8], severe=10 to 14 [n=6]), and their demographically matched control subjects with normal hepatic function (n=14 total). The first subject with severe hepatic impairment was enrolled after ≥2 subjects with mild and ≥2 subjects with moderate hepatic impairment had been enrolled and followed for ≥48 hours after dosing to ensure no observed significant safety signals. On Day 1, subjects received a single oral dose of etrasimod 2 mg after a ≥10 hour fast. PK and safety data were collected over a 21-day follow-up period. Results Thirty-six subjects were enrolled and dosed; 35 subjects completed the study. When compared with their respective demographically matched normal control groups, single dose etrasimod peak exposure (Cmax) was comparable for all hepatic impairment groups, whereas etrasimod total exposure (AUC) measures were progressively higher (up to 57.3% higher) in the mild, moderate, and severe hepatic impairment groups (Table 1). Unbound etrasimod Cmax values were progressively lower (up to 42.0% lower) in the mild, moderate, and severe hepatic impairment groups, whereas unbound etrasimod AUC values were typically comparable for all hepatic impairment groups, when compared with their respective demographically matched normal control groups (Table 2). Etrasimod t1/2 only moderately increased as hepatic function decreased, with mean values ranging from 43.9 to 59.5 hours in the demographically matched normal control groups and mean values of 55.7, 69.7, and 76.5 hours in the mild, moderate, and severe hepatic impairment groups, respectively. A single oral dose of etrasimod 2 mg was well tolerated; there were no clinically significant safety findings when administered to subjects with normal hepatic function or subjects with mild, moderate, or severe hepatic impairment. Conclusion A single oral dose of etrasimod 2 mg was well tolerated, with relatively modest changes in etrasimod exposure observed in subjects with mild, moderate, or severe hepatic impairment. These results suggest that etrasimod dose adjustment may not be warranted in subjects with hepatic impairment.

SAFETY OF AMISELIMOD IN HEALTHY SUBJECTS: RESULTS FROM A PHASE 1 RANDOMIZED, DOUBLE-BLIND, PLACEBO-CONTROLLED STUDY

To evaluate the safety profile of amiselimod, a selective sphingosine 1-phosphate receptor modulator which has been shown to regulate lymphocyte trafficking and is in development for the treatment of inflammatory bowel disease.

SAFETY OF AMISELIMOD IN HEALTHY SUBJECTS: RESULTS FROM A PHASE 1 RANDOMIZED, DOUBLE-BLIND, PLACEBO-CONTROLLED STUDY

Abstract Objective To evaluate the safety profile of amiselimod, a selective sphingosine 1-phosphate receptor modulator which has been shown to regulate lymphocyte trafficking and is in development for the treatment of inflammatory bowel disease. Methods A randomized, double-blind, multiple-dose, placebo-controlled, parallel study with a nested crossover design evaluated the safety and tolerability profile of amiselimod. Healthy adults were randomized in a 2:1:1 ratio during a 28-day treatment period accordingly: a single dose of placebo followed by oral amiselimod (upwardly titrated in doses ranging from 0.4 to 1.6 mg to achieve 0.4 mg and 0.8 mg steady-state exposure; a single dose of oral moxifloxacin 400 mg followed by placebo; or placebo followed by a single dose of moxifloxacin 400 mg. The safety population included all subjects who received at least one dose of treatment. Adverse events (AE) and serious AEs were collected. Treatment-emergent AEs were defined as an AE that was starting or worsening at the time of or after study drug administration. Changes in clinical laboratory parameters (including lymphocyte counts), physical examinations, vital signs, and electrocardiogram parameters (including heart rate, PR, QRS, and QT intervals) were recorded. Subjects were permitted to withdraw if lymphocyte counts were ≤ 0.2 x 109/L. Results The safety population included 190 subjects of which 95 received amiselimod and 95 were in the combined moxifloxacin group. Subjects were 40% female, 83% white, and the mean (standard deviation) age was 39.0 (8.8) years. The discontinuation rate was 8% (n=8) in the amiselimod group and 4% (n=4) in the moxifloxacin group. Three subjects who received amiselimod discontinued because they met the stopping criteria for low lymphocyte counts. One subject experienced an amiselimod-related serious AE of atrial fibrillation on day 26 (after receiving amiselimod 1.6 mg for 3 of the preceding 4 days) that required hospitalization, cardioversion, and led to discontinuation. No deaths were reported. All other AEs were mild to moderate in severity. Decreased white blood counts were the most commonly reported TEAE, followed by headache and constipation (Table). Reductions in white blood counts returned to normal range after study discontinuation without sequelae. Decreased neutrophils, lymphocytes and hemoglobin, and increased creatine kinase, alanine aminotransferase, and aspartate aminotransferase were reported, all of which resolved without sequelae. The mean absolute lymphocyte count for amiselimod exhibited a gradual decrease from predose (1.681 thou/uL) to a nadir of 0.424 thou/uL on day 27 (Figure). Changes to vital signs, physical examinations, and ECG parameters were within normal limits. Conclusions Upwardly titrated doses of amiselimod ranging from 0.4 to 1.6 mg were generally well tolerated in healthy subjects.

Probing the substitution pattern of indole-based scaffold reveals potent and selective sphingosine kinase 2 inhibitors

Elevated levels of sphingosine 1-phosphate (S1P) and increased expression of sphingosine kinase isoforms (SphK1 and SphK2) have been implicated in a variety of disease states including cancer, inflammation, and autoimmunity. Consequently, the S1P signaling axis has become an attractive target for drug discovery. Selective inhibition of either SphK1 or SphK2 has been demonstrated to be effective in modulating S1P levels in animal models. While SphK1 inhibitors have received much attention, the development of potent and selective SphK2 inhibitors are emerging. Previously, our group reported a SphK2 naphthalene-based selective inhibitor, SLC5081308, which displays approximately 7-fold selectivity for hSphK2 over hSphK1 and has a SphK2 Ki value of 1.0μM. To improve SphK2 potency and selectivity, we designed, synthesized, and evaluated a series of indole-based compounds derived from SLC5081308. After investigating substitution patterns around the indole ring, we discovered that 1,5-disubstitution promoted optimal binding in the SphK2 substrate binding site and subsequent inhibition of enzymatic activity. Our studies led to the identification of SLC5101465 (6r, SphK2 Ki=90nM, >110 fold selective for SphK2 over SphK1). Molecular modeling studies revealed key nonpolar interactions with Val308, Phe548, His556, and Cys533 and hydrogen bonds with both Asp211 and Asp308 as responsible for the high SphK2 inhibition and selectivity.

Current and emerging disease-modulatory therapies and treatment targets for multiple sclerosis.

The treatment of multiple sclerosis (MS), the most common chronic inflammatory, demyelinating and neurodegenerative disease of the central nervous system (CNS), continues to transform. In recent years, a number of novel and increasingly effective disease‐modulatory therapies (DMTs) have been approved, including oral fumarates and selective sphingosine 1‐phosphate modulators, as well as cell‐depleting therapies such as cladribine, anti‐CD20 and anti‐CD52 monoclonals. Amongst DMTs in clinical development, inhibitors of Bruton's tyrosine kinase represent an entirely new emerging drug class in MS, with three different drugs entering phase III trials. However, important remaining fields of improvement comprise tracking of long‐term benefit‐risk with existing DMTs and exploration of novel treatment targets relating to brain inherent disease processes underlying the progressive neurodegenerative aspect of MS, which accumulating evidence suggests start already early in the disease process. The aim here is to review current therapeutic options in relation to an improved understanding of the immunopathogenesis of MS, also highlighting examples where controlled trials have not generated the desired results. An additional aim is to review emerging therapies undergoing clinical development, including agents that interfere with disease processes believed to be important for neurodegeneration or aiming to enhance reparative responses. Notably, early trials now have shown initial evidence of enhanced remyelination both with small molecule compounds and biologicals. Finally, accumulating evidence from clinical trials and post‐marketing real‐world patient populations, which underscore the importance of early high effective therapy whilst maintaining acceptable tolerability, is discussed.

Validation of highly selective sphingosine kinase 2 inhibitors SLM6031434 and HWG-35D as effective anti-fibrotic treatment options in a mouse model of tubulointerstitial fibrosis

Renal fibrosis is characterized by chronic inflammation and excessive accumulation of extracellular matrix and progressively leads to functional insufficiency and even total loss of kidney function. In this study we investigated the anti-fibrotic potential of two highly selective and potent SK2 inhibitors, SLM6031434 and HWG-35D, in unilateral ureter obstruction (UUO), a model for progressive renal fibrosis, in mice. In both cases, treatment with SLM6031434 or HWG-35D resulted in an attenuated fibrotic response to UUO in comparison to vehicle-treated mice as demonstrated by reduced collagen accumulation and a decreased expression of collagen-1 (Col1), fibronectin-1 (FN-1), connective tissue growth factor (CTGF), and α-smooth muscle actin (α-SMA). Similar to our previous study in Sphk2−/− mice, we found an increased protein expression of Smad7, a negative regulator of the pro-fibrotic TGFβ/Smad signalling cascade, accompanied by a strong accumulation of sphingosine in SK2 inhibitor-treated kidneys. Treatment of primary renal fibroblasts with SLM6031434 or HWG-35D dose-dependently increased Smad7 expression and ameliorated the expression of Col1, FN-1 and CTGF.In summary, these data prove the anti-fibrotic potential of SK2 inhibition in a mouse model of renal fibrosis, thereby validating SK2 as pharmacological target for the treatment of fibrosis in chronic kidney disease.

P045 Effect of Etrasimod on Circulating Lymphocyte Subsets: Data From a Randomized Phase 1 Study in Healthy Japanese and Caucasian Men.

BACKGROUND: Etrasimod, a selective sphingosine 1-phosphate (S1P) receptor 1,4,5 modulator that reduces peripheral lymphocytes and subsequently impedes their recruitment to sites of inflammation, is in development for chronic immune-mediated inflammatory diseases. Reduction in pro-inflammatory immune cells without causing broad immunosuppression is an important treatment goal in patients with these diseases. This study evaluated the effect of etrasimod on circulating lymphocyte subsets in healthy volunteers to improve understanding of its proposed mechanism of action. METHODS: In this phase 1, single-blind (subject only) pharmacokinetic (PK) and pharmacodynamic study, 49 healthy Japanese and Caucasian men were randomized to receive once daily oral etrasimod 1 mg (n = 20), 2 mg (n = 20), or matching placebo (n = 9) from Days 1 to 7, followed by a 7-day washout and a single dose on Day 15. Absolute lymphocyte counts (ALC) were determined by complete blood count with differential. Immune cell subsets were evaluated by flow cytometry from isolated peripheral blood mononuclear cells (PBMCs) collected pre-dose on Days 1, 3, 5, 7, and 15. Change from baseline on 24 different immune cell subtypes were evaluated using a mixed-effects model. Paired t-tests were computed to evaluate significant subtype modulations in etrasimod-treated groups vs placebo at Day 7. RESULTS: Compared with placebo, etrasimod 1 and 2 mg dosed daily for 7 days resulted in similar dose dependent reductions in ALC in both ethnic groups, with total lymphocytes returning to at least 84% of baseline at Day 15. Compared with placebo, etrasimod induced reductions in mean percent change from baseline to Day 7 in total T cells, total CD4+ and CD8+ T cells, naive CD4+ and CD8+ T cells, central memory CD4+ and CD8+ T cells, effector memory CD4+ and CD8+ T cells, Th2 and Th17 cells, and total B cells. Etrasimod resulted in greater decreases in naive and central memory T cells than in effector memory T cells. Decreased immune cell subsets recovered to at least 70% of baseline pre-dose on Day 15, after the 7-day washout period. No notable treatment effects were seen on monocytes, macrophages, or CD56dim NK cells. Changes in immune cell populations were similar between Japanese and Caucasian subjects. Etrasimod 1 and 2 mg once-daily dosing regimens were safe and generally well tolerated. No adverse events related to low lymphocyte values occurred. CONCLUSION: Etrasimod effects on ALC and immune cell subsets were consistent with its known mechanism of action and observations for other S1P receptor modulators. Little or no ethnic group differences in etrasimod effects on ALC and immune cell subsets were observed in this study. The effect of etrasimod on onset and offset of immune modulation is consistent with etrasimod PK, with a typical half-life of approximately 33 hours. The differential effects of etrasimod on immune cell subsets may allow for a reduction in inflammation while maintaining immune surveillance. The lymphocyte subset profile suggests that etrasimod reduces certain immune cells and behaves as a selective immunomodulator rather than as a broad immunosuppressive agent.

A Novel Selective Sphingosine Kinase 2 Inhibitor, HWG-35D, Ameliorates the Severity of Imiquimod-Induced Psoriasis Model by Blocking Th17 Differentiation of Naïve CD4 T Lymphocytes.

Sphingosine kinases (SK) catalyze the phosphorylation of sphingosine to generate sphingosine-1-phosphate. Two isoforms of SK (SK1 and SK2) exist in mammals. Previously, we showed the beneficial effects of SK2 inhibition, using ABC294640, in a psoriasis mouse model. However, ABC294640 also induces the degradation of SK1 and dihydroceramide desaturase 1 (DES1). Considering these additional effects of ABC294640, we re-examined the efficacy of SK2 inhibition in an IMQ-induced psoriasis mouse model using a novel SK2 inhibitor, HWG-35D, which exhibits nM potency and 100-fold selectivity for SK2 over SK1. Topical application of HWG-35D ameliorated IMQ-induced skin lesions and normalized the serum interleukin-17A levels elevated by IMQ. Application of HWG-35D also decreased skin mRNA levels of interleukin-17A, K6 and K16 genes induced by IMQ. Consistent with the previous data using ABC294640, HWG-35D also blocked T helper type 17 differentiation of naïve CD4+ T cells with concomitant reduction of SOCS1. Importantly, HWG-35D did not affect SK1 or DES1 expression levels. These results reaffirm an important role of SK2 in the T helper type 17 response and suggest that highly selective and potent SK2 inhibitors such as HWG-35D might be of therapeutic use for the treatment of psoriasis.

Siponimod: A Review in Secondary Progressive Multiple Sclerosis.

Oral siponimod (Mayzent®), a next-generation, selective sphingosine 1-phosphate receptor (S1PR) 1 and 5 modulator, is approved in several countries for the treatment of secondary progressive multiple sclerosis (SPMS), with specific indications varying between individual countries. In the pivotal EXPAND trial (median duration double-blind treatment 18 months) in a broad spectrum of patients with SPMS, once-daily oral siponimod 2 mg (initial dose titration over 6 days) was significantly more effective than placebo in reducing clinical and MRI-defined outcomes of disease activity and disability progression, including 3-month confirmed disability progression on the Expanded Disability Status Scale (EDSS), and was generally well tolerated in the core phase of the study. These beneficial effects of siponimod appeared to be sustained during up to 5 years of treatment in the ongoing open-label extension phase of EXPAND. The safety profile of siponimod is similar to that of other agents in its class, including adverse events of special interest (i.e. those known to be associated with S1PR modulators). No new safety signals were identified during up to 5 years’ treatment in the open-label extension phase. Albeit further long-term efficacy and safety data from the real-world setting are required to fully define its role, given the paucity of current treatment options and its convenient dosage regimen, siponimod represents an important emerging option for the treatment of adult patients with SPMS with active disease evidenced by relapses or imaging-features of inflammatory activity.

Structure-activity relationship studies and bioactivity evaluation of 1,2,3-triazole containing analogues as a selective sphingosine kinase-2 inhibitors.

Sphingosine kinase (SphK) is primarily responsible for the production of Sphingosine-1-phosphate (S1P) that plays an important role in many biological and pathobiological processes including cancer, inflammation, neurological and cardiovascular disorders. Most research has focused on developing inhibitors of SphK1 rather than inhibitors of the other isoform SphK2 which has great importance in several pathophysiologic pathways. Exploration of new analogues for improving the potency and selectivity of SphK2 inhibitors is critical. We now have designed, synthesized, and evaluated eighteen new 1,2,3-triazole analogues for their SphK2 inhibitory activity using a ADP-Glo kinase assay, and explored their invivo anti-tumor bioactivity. Several compounds including 21c, 21e, 21g, 25e-h, 29a-c have high selectivity for SphK2 over SphK1; compound 21g displayed the highest potency with an IC50 value of 0.23μM. In addition, three compounds 21a, 21b, and 25b have high anti-tumor activity against U-251 MG human glioblastoma cells. Molecular modeling study was performed to elucidate the polar head group and 1,2,3-triazole pharmacophore impact on the SphK2 selectivity.