Long-term Safety and Efficacy of Etrasimod for Ulcerative Colitis: Results from the Open-label Extension of the OASIS Study.

BACKGROUND AND AIMS: Etrasimod is an oral, selective, sphingosine 1-phosphate receptor modulator. In a phase 2, randomised, double-blind, placebo-controlled trial in adults with moderately-to-severely active ulcerative colitis [OASIS], etrasimod 2 mg provided significant benefit versus placebo and was generally well tolerated. This open-label extension [OLE] evaluated safety and efficacy of etrasimod for up to 52 weeks. METHODS: In OASIS, 156 patients received etrasimod 1 mg, etrasimod 2 mg, or placebo, once daily for 12 weeks. After completing OASIS, patients could enrol in the OLE and receive etrasimod 2 mg for an additional 34-40 weeks. RESULTS: In all, 118 patients enrolled in the OLE; 112 patients received etrasimod 2 mg at any point and were evaluated for safety and efficacy. A total of 92 [82%] patients who received etrasimod 2 mg in the OLE completed the study. Treatment-emergent adverse events occurred in 60% [67/112] of patients receiving etrasimod 2 mg at any time, most commonly worsening ulcerative colitis and anaemia; 94% of adverse events were mild/moderate. At end of treatment, 64% of patients met the criteria for clinical response, 33% for clinical remission, and 43% for endoscopic improvement. Week 12 clinical response, clinical remission, or endoscopic improvement was maintained to end of treatment in 85%, 60%, or 69% of patients, respectively. Steroid-free clinical remission occurred in 22% of overall patients. CONCLUSIONS: In this long-term extension study, etrasimod 2 mg demonstrated a favourable safety profile. Most patients with clinical response, clinical remission, or endoscopic improvement at Week 12 maintained that status to end of treatment.

Efficacy and Safety of Etrasimod in a Phase 2 Randomized Trial of Patients With Ulcerative Colitis.

BACKGROUND & AIMS: Etrasimod (APD334) is an oral, selective sphingosine 1-phosphate receptor modulator in development for immune-mediated inflammatory disorders. We assessed the efficacy and safety of etrasimod in patients with moderately to severely active ulcerative colitis (UC). METHODS: In a phase 2, proof-of-concept, double-blind, parallel-group study, adult outpatients with modified Mayo Clinic scores (MCSs) (stool frequency, rectal bleeding, and endoscopy findings) of 4-9, endoscopic subscores of 2 or more, and rectal bleeding subscores of 1 or more were randomly assigned to groups given once-daily etrasimod 1 mg (n = 52), etrasimod 2 mg (n = 50), or placebo (n = 54) for 12 weeks. The study was performed from October 15, 2015, through February 14, 2018, at 87 centers in 17 countries. The primary endpoint was an increase in the mean improvement in modified MCS from baseline to week 12. Secondary endpoints included the proportion of patients with endoscopic improvement (subscores of 1 or less) from baseline to week 12. Exploratory endpoints, including clinical remission, are reported in the article, although the study was statistically powered to draw conclusions only on the primary endpoint. RESULTS: At week 12, the etrasimod 2 mg group met the primary and all secondary endpoints. Etrasimod 2 mg led to a significantly greater increase in mean improvement in modified MCS from baseline than placebo (difference from placebo, 0.99 points; 90% confidence interval, 0.30-1.68; P = .009), and etrasimod 1 mg led to an increase in mean improvement from baseline in modified MCS of 0.43 points more than placebo (90% confidence interval, reduction of 0.24 to increase of 1.11; nominal P = .15). Endoscopic improvement occurred in 41.8% of patients receiving etrasimod 2 mg vs 17.8% receiving placebo (P = .003). Most adverse events were mild to moderate. Three patients had a transient, asymptomatic, low-grade atrioventricular block that resolved spontaneously all patients had evidence of atrioventricular block before etrasimod exposure. CONCLUSIONS: In patients with moderately to severely active ulcerative colitis, etrasimod 2 mg was more effective than placebo in producing clinical and endoscopic improvements. Further clinical development is warranted. Clinicaltrials.gov, Number: NCT02447302.

Peroxisome proliferator-activated receptor-α activation promotes macrophage reverse cholesterol transport through a liver X receptor-dependent pathway.

OBJECTIVE: Peroxisome proliferator-activated receptor-α (PPARα) activation has been shown in vitro to increase macrophage cholesterol efflux, the initial step in reverse cholesterol transport (RCT). However, it remains unclear whether PPARα activation promotes macrophage RCT in vivo. METHODS AND RESULTS: We demonstrated that a specific potent PPARα agonist GW7647 inhibited atherosclerosis and promoted macrophage RCT in hypercholesterolemic mice expressing the human apolipoprotein A-I (apoA-I) gene. We compared the effect of GW7647 on RCT in human apoA-I transgenic (hA-ITg) mice with wild-type mice and showed that the PPARα agonist promoted RCT in hA-ITg mice to a much greater extent than in wild-type mice, indicating that human apoA-I expression is important for PPARα-induced RCT. We further investigated the dependence of the macrophage PPARα-liver X receptor (LXR) pathway on the promotion of RCT by GW7647. Primary murine macrophages lacking PPARα or LXR abolished the ability of GW7647 to promote RCT in hA-ITg mice. In concert, the PPARα agonist promoted cholesterol efflux and ATP binding cassette transporter A1/G1 expression in primary macrophages, and this was also by the PPARα-LXR pathway. CONCLUSION: Our observations demonstrate that a potent PPARα agonist promotes macrophage RCT in vivo in a manner that is enhanced by human apoA-I expression and dependent on both macrophage PPARα and LXR expression.

PPARγ activation redirects macrophage cholesterol from fecal excretion to adipose tissue uptake in mice via SR-BI.

PPARγ agonists, used in the treatment of Type 2 diabetes, can raise HDL-cholesterol, therefore could potentially stimulate macrophage-to-feces reverse cholesterol transport (RCT). We aimed to test whether PPARγ activation promotes macrophage RCT in vivo. Macrophage RCT was assessed in mice using cholesterol loaded/(3)H-cholesterol labeled macrophages. PPARγ agonist GW7845 (20 mg/kg/day) did not change (3)H-tracer plasma appearance, but surprisingly decreased fecal (3)H-free sterol excretion by 43% (P<0.01) over 48h. Total free cholesterol efflux from macrophages to serum (collected from control and GW7845 groups) was not different, although ABCA1-mediated efflux was significantly higher with GW7845. To determine the effect of PPARγ activation on HDL cholesterol uptake by different tissues, the metabolic fate of HDL labeled with (3)H-cholesteryl ether (CE) was also measured. We observed two-fold increase in HDL derived (3)H-CE uptake by adipose tissue (P<0.005) with concomitant 22% decrease in HDL derived (3)H-CE uptake by the liver (P<0.05) in GW7845 treated wild type mice. This was associated with a significant increase in SR-BI protein expression in adipose tissue, but not liver. The same experiment in SR-BI knockout mice, showed no difference in HDL derived (3)H-CE uptake by adipose tissue or liver. In conclusion, PPARγ activation decreases the fecal excretion of macrophage derived cholesterol in mice. This is not due to inhibition of cholesterol efflux from macrophages, but rather involves redirection of effluxed cholesterol from liver towards adipose tissue uptake via SR-BI. This represents a novel mechanism for regulation of RCT and may extend the therapeutic implications of these ligands.

Both the peroxisome proliferator-activated receptor delta agonist, GW0742, and ezetimibe promote reverse cholesterol transport in mice by reducing intestinal reabsorption of HDL-derived cholesterol.

Peroxisome proliferator-activated receptor delta (PPARdelta) agonism increases HDL cholesterol and has therefore the potential to stimulate macrophage-to-feces reverse cholesterol transport (RCT). To test whether PPARdelta activation promotes RCT in mice, in vivo macrophage RCT was assessed using cholesterol-loaded/3H-cholesterol-labeled macrophages injected intraperitoneally. PPARdelta agonist GW0742 (10 mg/kg per day) did not change 3H-tracer plasma appearance, but increased fecal 3H-free sterols excretion by 103% ( p < 0.005) over 48 hours. Total free cholesterol efflux from macrophages to serum (collected from both control and GW0742 groups) was not different, although ABCA1-mediated efflux was significantly higher with GW0742. The metabolic fate of HDL labeled with 3H- cholesteryl ether or 3H-cholesteryl oleate was also measured. While 3H-cholesteryl ether tissue uptake was unchanged, the 3H-tracer recovered in fecal free sterol fraction after 3H-cholesteryl oleate injection increased by 88% with GW0742 ( p < 0.0005). This was associated with a lower Niemann-Pick C1 like 1 (NPC1L1) mRNA expression in the small intestine ( p < 0.05). The same experiments in mice treated with ezetimibe, which blocks NPC1L1, showed a similar 2-fold increase in fecal free sterol excretion after labeled macrophages orHDL injection. In conclusion, PPARdelta activation enhances excretion of macrophage or HDL-derived cholesterol in feces through reduced NPC1L1 expression in mice, comparable to the effect of ezetimibe.

Pharmacological activation of liver X receptors promotes reverse cholesterol transport in vivo.

BACKGROUND: Liver X receptors (LXRs) are ligand-activated transcription factors involved in the control of lipid metabolism and inflammation. Synthetic LXR agonists have been shown to inhibit the progression of atherosclerosis in mice, but the mechanism is uncertain. LXR agonism upregulates the genes encoding ATP binding cassette transporters A1 (ABCA1) and G1 (ABCG1) in macrophages, thus promoting efflux of cholesterol; it also upregulates liver and intestinal ABCG5 and ABCG8, helping to promote biliary and fecal excretion of cholesterol. Thus, LXR agonism may inhibit atherosclerosis through promotion of reverse cholesterol transport (RCT) in vivo, but this has not been proven. We previously described an in vivo method to trace the movement of cholesterol from 3H-cholesterol-labeled J774 macrophages into plasma, into liver, and ultimately into the bile and feces as free cholesterol or bile acids. In the present study we used this approach to test the hypothesis that administration of the synthetic LXR agonist GW3965 would increase the rate of macrophage RCT in vivo. METHODS AND RESULTS: Three different mouse models-wild-type C57BL/6 mice, LDLR/apobec-1 double knockout mice, and human apolipoprotein (apo)B/cholesteryl ester transfer protein (CETP) double transgenic mice-were treated with either vehicle or GW3965. Mice were injected intraperitoneally with 3H-cholesterol-labeled and cholesterol-loaded macrophages and monitored for the appearance of 3H-tracer in plasma, liver, and feces. Administration of GW3965 significantly increased the levels of 3H-tracer in plasma and feces in all 3 mouse models. CONCLUSIONS: These results demonstrate that administration of the LXR agonist GW3965 increases the rate of RCT from macrophages to feces in vivo.