A Phase 3 Trial of Seladelpar in Primary Biliary Cholangitis.

BACKGROUND: Effective treatments for patients with primary biliary cholangitis are limited. Seladelpar, a peroxisome proliferator-activated receptor delta agonist, has potential benefits. METHODS: In this phase 3, 12-month, double-blind, placebo-controlled trial, we randomly assigned (in a 2:1 ratio) patients who had had an inadequate response to or who had a history of unacceptable side effects with ursodeoxycholic acid to receive oral seladelpar at a dose of 10 mg daily or placebo. The primary end point was a biochemical response, which was defined as an alkaline phosphatase level less than 1.67 times the upper limit of the normal range, with a decrease of 15% or more from baseline, and a normal total bilirubin level at month 12. Key secondary end points were normalization of the alkaline phosphatase level at month 12 and a change in the score on the pruritus numerical rating scale (range, 0 [no itch] to 10 [worst itch imaginable]) from baseline to month 6 among patients with a baseline score of at least 4 (indicating moderate-to-severe pruritus). RESULTS: Of the 193 patients who underwent randomization and treatment, 93.8% received ursodeoxycholic acid as standard-of-care background therapy. A greater percentage of the patients in the seladelpar group than in the placebo group had a biochemical response (61.7% vs. 20.0%; difference, 41.7 percentage points; 95% confidence interval [CI], 27.7 to 53.4, P<0.001). Normalization of the alkaline phosphatase level also occurred in a greater percentage of patients who received seladelpar than of those who received placebo (25.0% vs. 0%; difference, 25.0 percentage points; 95% CI, 18.3 to 33.2, P<0.001). Seladelpar resulted in a greater reduction in the score on the pruritus numerical rating scale than placebo (least-squares mean change from baseline, -3.2 vs. -1.7; least-squares mean difference, -1.5; 95% CI, -2.5 to -0.5, P = 0.005). Adverse events were reported in 86.7% of the patients in the seladelpar group and in 84.6% in the placebo group, and serious adverse events in 7.0% and 6.2%, respectively. CONCLUSIONS: In this trial involving patients with primary biliary cholangitis, the percentage of patients who had a biochemical response and alkaline phosphatase normalization was significantly greater with seladelpar than with placebo. Seladelpar also significantly reduced pruritus among patients who had moderate-to-severe pruritus at baseline. The incidence and severity of adverse events were similar in the two groups. (Funded by CymaBay Therapeutics; RESPONSE ClinicalTrials.gov number, NCT04620733; EudraCT number, 2020-004348-27.).

Open-label, clinical trial extension: Two-year safety and efficacy results of seladelpar in patients with primary biliary cholangitis.

BACKGROUND: Seladelpar is a potent and selective peroxisome proliferator-activated receptor-δ agonist that targets multiple cell types involved in primary biliary cholangitis (PBC), leading to anti-cholestatic, anti-inflammatory and anti-pruritic effects. AIMS: To evaluate the long-term safety and efficacy of seladelpar in patients with PBC. METHODS: In an open-label, international, long-term extension study, patients with PBC completing seladelpar lead-in studies continued treatment. Seladelpar was taken orally once daily at doses of 5 or 10 mg with dose adjustment permitted for safety or tolerability. The primary analysis was for safety and the secondary efficacy analysis examined biochemical markers of cholestasis and liver injury. The study was terminated early due to the unexpected histological findings in a concurrent study for non-alcoholic steatohepatitis, which were subsequently found to predate treatment. Safety and efficacy data were analysed through 2 years. RESULTS: There were no serious treatment-related adverse events observed among 106 patients treated with seladelpar for up to 2 years. There were four discontinuations for safety, one possibly related to seladelpar. Among 53 patients who completed 2 years of seladelpar, response rates increased from years 1 to 2 for the composite endpoint (alkaline phosphatase [ALP] <1.67 × ULN, ≥15% decrease in ALP, and total bilirubin ≤ULN) and ALP normalisation from 66% to 79% and from 26% to 42%, respectively. In those with elevated bilirubin at baseline, 43% achieved normalisation at year 2. CONCLUSIONS: Seladelpar was safe, and markedly improved biochemical markers of cholestasis and liver injury in patients with PBC. These effects were maintained or improved throughout the second year. CLINICALTRIALS: gov: NCT03301506; Clinicaltrialsregister.eu: 2017-003910-16.

Liver biopsy for assessment of suspected drug-induced liver injury in metabolic dysfunction-associated steatohepatitis clinical trials: Expert consensus from the Liver Forum.

BACKGROUND: Causality assessment of suspected drug-induced liver injury (DILI) during metabolic dysfunction-associated steatohepatitis (MASH) clinical trials can be challenging, and liver biopsies are not routinely performed as part of this evaluation. While the field is moving away from liver biopsy as a diagnostic and prognostic tool, information not identified by non-invasive testing may be provided on histology. AIM: To address the appropriate utilisation of liver biopsy as part of DILI causality assessment in this setting. METHODS: From 2020 to 2022, the Liver Forum convened a series of webinars on issues pertaining to liver biopsy during MASH trials. The Histology Working Group was formed to generate a series of consensus documents addressing these challenges. This manuscript focuses on liver biopsy as part of DILI causality assessment. RESULTS: Expert opinion, guidance and recommendations on the role of liver biopsy as part of causality assessment of suspected DILI occurring during clinical trials for a drug(s) being developed for MASH are provided. Lessons learned from prior MASH programs are reviewed and gaps identified. CONCLUSIONS: Although there are no pathognomonic features, histologic evaluation of suspected DILI during MASH clinical trials may alter patient management, define the pattern and severity of injury, detect findings that favour a diagnosis of DILI versus MASH progression, identify prognostic features, characterise the clinicopathological phenotype of DILI, and/or define lesions that influence decisions about trial discontinuation and further development of the drug.

Seladelpar combined with complementary therapies improves fibrosis, inflammation, and liver injury in a mouse model of nonalcoholic steatohepatitis.

Seladelpar, a selective peroxisome proliferator-activated receptor δ (PPARδ) agonist, improves markers of hepatic injury in human liver diseases, but histological improvement of nonalcoholic steatohepatitis (NASH) and liver fibrosis has been challenging with any single agent. To discover how complementary agents could work with seladelpar to achieve optimal outcomes, this study evaluated a variety of therapeutics (alone and in combination) in a mouse model of NASH. Mice on a high-fat amylin liver NASH (AMLN) diet were treated for 12 wk with seladelpar, GLP-1-R (glucagon-like peptide-1 receptor) agonist liraglutide, apoptosis signal-regulating kinase 1 (ASK1) inhibitor selonsertib, farnesoid X receptor (FXR) agonist obeticholic acid, and with seladelpar in combination with liraglutide or selonsertib. Seladelpar treatment markedly improved plasma markers of liver function. Seladelpar alone or in combination resulted in stark reductions in liver fibrosis (hydroxyproline, new collagen synthesis rate, mRNA indices of fibrosis, and fibrosis staining) compared with vehicle and the other single agents. Robust reductions in liver steatosis were also observed. Seladelpar produced a reorganization of metabolic gene expression, particularly for those genes promoting peroxisomal and mitochondrial lipid oxidation. In summary, substantial improvements in NASH and NASH-induced fibrosis were observed with seladelpar alone and in combination with liraglutide in this model. Broad gene expression analysis suggests seladelpar should be effective in concert with diverse mechanisms of action.NEW & NOTEWORTHY NASH is a chronic, progressive, and increasingly problematic liver disease that has been resistant to treatment with individual therapeutics. In this study using a diet-induced mouse model of NASH, we found that the PPARδ agonist seladelpar reduced fibrosis and NASH pathology alone and in combinations with a GLP-1-R agonist (liraglutide) or an ASK1 inhibitor (selonsertib). Liver transcriptome analysis comparing each agent and coadministration suggests seladelpar should be effective in combination with a variety of therapeutics.

Seladelpar treatment reduces IL-31 and pruritus in patients with primary biliary cholangitis.

BACKGROUND AND AIMS: Pruritus is a debilitating symptom for many people living with primary biliary cholangitis (PBC). In studies with seladelpar, a selective peroxisome proliferator-activated receptor-delta agonist, patients with PBC experienced significant improvement in pruritus and reduction of serum bile acids. Interleukin-31 (IL-31) is a cytokine known to mediate pruritus, and blocking IL-31 signaling provides relief in pruritic skin diseases. This study examined the connection between seladelpar's antipruritic effects and IL-31 and bile acid levels in patients with PBC. APPROACH AND RESULTS: IL-31 levels were quantified in serum samples from the ENHANCE study of patients with PBC receiving daily oral doses of placebo (n = 55), seladelpar 5 mg (n = 53) or 10 mg (n = 53) for 3 months, and for healthy volunteers (n = 55). IL-31 levels were compared with pruritus using a numerical rating scale (NRS, 0-10) and with bile acid levels. Baseline IL-31 levels closely correlated with pruritus NRS ( r = 0.54, p < 0.0001), and total ( r = 0.54, p < 0.0001) and conjugated bile acids (up to 0.64, p < 0.0001). Decreases in IL-31 were observed with seladelpar 5 mg (-30%, p = 0.0003) and 10 mg (-52%, p < 0.0001) versus placebo (+31%). Patients with clinically meaningful improvement in pruritus (NRS ≥ 2 decrease) demonstrated greater dose-dependent reductions in IL-31 compared to those without pruritus improvement (NRS < 2 decrease). Strong correlations were observed for the changes between levels of IL-31 and total bile acids ( r = 0.63, p < 0.0001) in the seladelpar 10 mg group. CONCLUSIONS: Seladelpar decreased serum IL-31 and bile acids in patients with PBC. The reductions of IL-31 and bile acids correlated closely with each other and pruritus improvement, suggesting a mechanism to explain seladelpar's antipruritic effects.

Seladelpar efficacy and safety at 3 months in patients with primary biliary cholangitis: ENHANCE, a phase 3, randomized, placebo-controlled study.

BACKGROUND AND AIMS: ENHANCE was a phase 3 study that evaluated efficacy and safety of seladelpar, a selective peroxisome proliferator-activated receptor-δ (PPAR) agonist, versus placebo in patients with primary biliary cholangitis with inadequate response or intolerance to ursodeoxycholic acid (UDCA). APPROACH AND RESULTS: Patients were randomized 1:1:1 to oral seladelpar 5 mg (n=89), 10 mg (n=89), placebo (n=87) daily (with UDCA, as appropriate). Primary end point was a composite biochemical response [alkaline phosphatase (ALP) < 1.67×upper limit of normal (ULN), ≥15% ALP decrease from baseline, and total bilirubin ≤ ULN] at month 12. Key secondary end points were ALP normalization at month 12 and change in pruritus numerical rating scale (NRS) at month 6 in patients with baseline score ≥4. Aminotransferases were assessed. ENHANCE was terminated early following an erroneous safety signal in a concurrent, NASH trial. While blinded, primary and secondary efficacy end points were amended to month 3. Significantly more patients receiving seladelpar met the primary end point (seladelpar 5 mg: 57.1%, 10 mg: 78.2%) versus placebo (12.5%) ( p < 0.0001). ALP normalization occurred in 5.4% ( p =0.08) and 27.3% ( p < 0.0001) of patients receiving 5 and 10 mg seladelpar, respectively, versus 0% receiving placebo. Seladelpar 10 mg significantly reduced mean pruritus NRS versus placebo [10 mg: -3.14 ( p =0.02); placebo: -1.55]. Alanine aminotransferase decreased significantly with seladelpar versus placebo [5 mg: 23.4% ( p =0.0008); 10 mg: 16.7% ( p =0.03); placebo: 4%]. There were no serious treatment-related adverse events. CONCLUSIONS: Patients with primary biliary cholangitis (PBC) with inadequate response or intolerance to UDCA who were treated with seladelpar 10 mg had significant improvements in liver biochemistry and pruritus. Seladelpar appeared safe and well tolerated.

A phase II, randomized, open-label, 52-week study of seladelpar in patients with primary biliary cholangitis.

BACKGROUND & AIMS: We examined the efficacy and safety of seladelpar, a selective peroxisome proliferator-activated receptor-delta agonist, in adults with primary biliary cholangitis (PBC) at risk of disease progression (alkaline phosphatase [ALP] ≥1.67xupper limit of normal [ULN]) who were receiving or intolerant to ursodeoxycholic acid. METHODS: In this 52-week, phase II, dose-ranging, open-label study, patients were randomized (1:1) to seladelpar 5 mg/day (n = 53) or 10 mg/day (n = 55) or assigned to 2 mg/day (n = 11; United Kingdom sites after interim analysis) for 12 weeks. Doses could then be uptitrated to 10 mg/day. The primary efficacy endpoint was ALP change from baseline to Week 8. RESULTS: Mean baseline ALP was 300, 345, and 295 U/L in the 2 mg, 5 mg, and 10 mg cohorts, respectively. Twenty-one percent of patients had cirrhosis, 71% had pruritus. At Week 8, mean ± standard error ALP reductions from baseline were 26 ± 2.8%, 33 ± 2.6%, and 41 ± 1.8% in the 2 mg (n = 11), 5 mg (n = 49), and 10 mg (n = 52) cohorts (all p ≤0.005), respectively. Responses were maintained or improved at Week 52, after dose escalation in 91% and 80% of the 2 mg and 5 mg cohorts, respectively. At Week 52, composite response (ALP <1.67xULN, ≥15% ALP decrease, and normal total bilirubin) rates were 64%, 53%, and 67%, and ALP normalization rates were 9%, 13%, and 33% in the 2 mg, 5 mg, and 10 mg cohorts, respectively. Pruritus visual analog scale score was decreased in the 5 mg and 10 mg cohorts. There were no treatment-related serious adverse events, and 4 patients discontinued due to adverse events. CONCLUSIONS: Seladelpar demonstrated robust, dose-dependent, clinically significant, and durable improvements in biochemical markers of cholestasis and inflammation in patients with PBC at risk of disease progression. Seladelpar appeared safe and well tolerated and was not associated with any increase in pruritus. GOV NUMBER: NCT02955602 CLINICALTRIALSREGISTER. EU NUMBER: 2016-002996-91 LAY SUMMARY: Current treatment options for patients living with primary biliary cholangitis (PBC) are not optimal due to inadequate effectiveness or undesirable side effects. Patients with PBC who took seladelpar, a new treatment being developed for PBC, at increasing doses (2, 5, or 10 mg/day) for 1 year had clinically significant, dose-dependent improvements in key liver tests. Treatment appeared safe and was not associated with any worsening in patient self-reported itch scores.

Seladelpar improved measures of pruritus, sleep, and fatigue and decreased serum bile acids in patients with primary biliary cholangitis.

BACKGROUND & AIMS: Primary biliary cholangitis (PBC) can result in life-altering cholestatic pruritus and fatigue, but treatment options are limited. Seladelpar, a peroxisome proliferator-activated receptor-delta (PPARδ) agonist, has demonstrated potent anti-cholestatic effects in clinical studies. This open-label, uncontrolled phase 2 study in PBC patients evaluated the effects of 1-year of seladelpar treatment on measures of pruritus and quality of life. METHODS: Self-reported experiences of 101 PBC patients were collected at baseline and after 1 year of seladelpar treatment using the pruritus visual analog scale (VAS), 5D-itch scale, and PBC-40 questionnaires along with bile acid profiles. RESULTS: In patients with moderate-to-severe pruritus, substantial improvement in pruritus was seen in 58% and 93% of patients in 5/10 mg and 10 mg treatment groups, respectively. After 1 year, patients reporting improvement substantially outnumbered those who worsened in the total 5-D itch (including individual domains) and PBC-40 (itch and fatigue domains) questionnaires. Improvement in sleep disturbance at 1-year was reported in 81% (5/10 mg) and 78% (10 mg) of the patients with baseline itch-related sleep disturbance by 5-D itch score with similar results using the PBC-40 sleep questionnaire. Seladelpar-treated patients had significant reductions of 46% (5/10 mg) and 31% (10 mg) in the serum bile acid precursor C4 and reductions of up to 38% in serum bile acids. CONCLUSIONS: Seladelpar treatment for 1 year led to consistent improvement in both symptom burden and biochemical response, suggesting its potential as a single agent to address two key unmet needs in PBC patients.

Seladelpar (MBX-8025), a selective PPAR-δ agonist, in patients with primary biliary cholangitis with an inadequate response to ursodeoxycholic acid: a double-blind, randomised, placebo-controlled, phase 2, proof-of-concept study.

BACKGROUND: Many patients with primary biliary cholangitis have an inadequate response to first-line therapy with ursodeoxycholic acid. Seladelpar is a potent, selective agonist for the peroxisome proliferator-activated receptor-delta (PPAR-δ), which is implicated in bile acid homoeostasis. This first-in-class study evaluated the anti-cholestatic effects and safety of seladelpar in patients with an inadequate response to ursodeoxycholic acid. METHODS: The study was a 12-week, double-blind, placebo-controlled, phase 2 trial of patients with alkaline phosphatase of at least 1·67 times the upper limit of normal (ULN) despite treatment with ursodeoxycholic acid. Patients, recruited at 29 sites in North America and Europe, were randomly assigned to placebo, seladelpar 50 mg/day, or seladelpar 200 mg/day while ursodeoxycholic acid was continued. Randomisation was done centrally (1:1:1) by a computerised system using an interactive voice-web response system with a block size of three. Randomisation was stratified by region (North America and Europe). The primary outcome was the percentage change from baseline in alkaline phosphatase over 12 weeks, analysed in the modified intention-to-treat (ITT) population (any randomised patient who received at least one dose of medication and had at least one post-baseline alkaline phosphatase evaluation). This study is registered with ClinicalTrials.gov (NCT02609048) and the EU Clinical Trials Registry (EudraCT2015-002698-39). FINDINGS: Between Nov 4, 2015, and May 26, 2016, 70 patients were screened at 29 sites in North America and Europe. During recruitment, three patients treated with seladelpar developed fully reversible, asymptomatic grade 3 alanine aminotransferase increases (one on 50 mg, two on 200 mg), ranging from just over five to 20 times the ULN; as a result, the study was terminated after 41 patients were randomly assigned. The modified ITT population consisted of 12 patients in the placebo group, 13 in the seladelpar 50 mg group, and 10 in the seladelpar 200 mg group. Mean changes from baseline in alkaline phosphatase were -2% (SD 16) in the placebo group, -53% (14) in the seladelpar 50 mg group, and -63% (8) in the seladelpar 200 mg group. Changes in both seladelpar groups versus placebo were significant (p<0·0001 for both groups vs placebo), with no significant difference between the two seladelpar groups (p=0·1729). All five patients who received seladelpar for 12 weeks had normal alkaline phosphatase values at the end of treatment, based on a central laboratory ULN for alkaline phosphatase of 116 U/L. The most frequently reported adverse events were pruritus (16%; one patient on placebo, four on seladelpar 50 mg, and one on seladelpar 200 mg), nausea (13%; one patient on placebo, three on seladelpar 50 mg, and one on seladelpar 200 mg), diarrhoea (10%; two patients on placebo, one on seladelpar 50 mg, and one on seladelpar 200 mg), dyspepsia (8%; two patients on seladelpar 50 mg and one on seladelpar 200 mg), muscle spasms (8%; three patients on seladelpar 200 mg), myalgia (8%; one patient on placebo and two on seladelpar 200 mg), and dizziness (8%; one patient on placebo and two on seladelpar 50 mg). INTERPRETATION: Seladelpar normalised alkaline phosphatase levels in patients who completed 12 weeks of treatment. However, treatment was associated with grade 3 increases in aminotransferases and the study was stopped early. The effects of seladelpar should be explored at lower doses. FUNDING: CymaBay Therapeutics.

The Pharmacodynamics, Pharmacokinetics, and Safety of Arhalofenate in Combination with Febuxostat When Treating Hyperuricemia Associated with Gout.

OBJECTIVE: Arhalofenate (ARH), in development for gout, has uricosuric and anti-flare activities. ARH plus febuxostat (FBX) were evaluated in subjects with gout for serum uric acid (SUA) lowering, drug interaction, and safety. METHODS: Open phase II trial in gout volunteers (NCT02252835). Cohort 1 received ARH 600 mg for 2 weeks, followed by sequential 1-week co-administration of FBX 80 mg followed by 40 mg. FBX 40 mg was continued alone for 2 weeks. Cohort 2 received ARH 800 mg for 2 weeks, followed by sequential 1-week co-administration of FBX 40 mg followed by 80 mg. FBX 80 mg was continued alone for 2 weeks. SUA, its fractional excretion (FEUA), and plasma oxypurines were assessed. Pharmacokinetics of FBX and ARH were determined alone and in combination for cohort 2. RESULTS: Baseline mean SUA was 9.4 mg/dl for cohort 1 (n = 16) and 9.2 mg/dl for cohort 2 (n = 16). The largest SUA decrease (63%) was observed with ARH 800 mg + FBX 80 mg, with all subjects reaching SUA < 6 mg/dl and 93% < 5 mg/dl. The area under the curve (AUC)(0-t) of ARH acid + FBX/ARH acid was 108%. The AUC(0-t) of FBX + ARH acid/FBX was 87%. As expected, FBX increased oxypurines and increases were unaffected by ARH co-administration. Baseline FEUA were low (3.5%-4.6%) and ARH increased them toward normal without overexcretion of UA. ARH was well tolerated and appeared safe. CONCLUSION: ARH and FBX lowered SUA by complementary mechanisms. The combination provided greater decreases than each drug alone. The combination was well tolerated and appeared safe. TRIAL REGISTRATION: NCT02252835.

The selective peroxisome proliferator-activated receptor-delta agonist seladelpar reverses nonalcoholic steatohepatitis pathology by abrogating lipotoxicity in diabetic obese mice.

Lipotoxicity associated with insulin resistance is central to nonalcoholic steatohepatitis (NASH) pathogenesis. To date, only weight loss fully reverses NASH pathology, but mixed peroxisome proliferator-activated receptor-alpha/delta (PPAR-α/δ) agonists show some efficacy. Seladelpar (MBX-8025), a selective PPAR-δ agonist, improves atherogenic dyslipidemia. We therefore used this agent to test whether selective PPAR-δ activation can reverse hepatic lipotoxicity and NASH in an obese, dyslipidemic, and diabetic mouse model. From weaning, female Alms1 mutant (foz/foz) mice and wild-type littermates were fed an atherogenic diet for 16 weeks; groups (n = 8-12) were then randomized to receive MBX-8025 (10 mg/kg) or vehicle (1% methylcellulose) by gavage for 8 weeks. Despite minimally altering body weight, MBX-8025 normalized hyperglycemia, hyperinsulinemia, and glucose disposal in foz/foz mice. Serum alanine aminotransferase ranged 300-600 U/L in vehicle-treated foz/foz mice; MBX-8025 reduced alanine aminotransferase by 50%. In addition, MBX-8025 normalized serum lipids and hepatic levels of free cholesterol and other lipotoxic lipids that were increased in vehicle-treated foz/foz versus wild-type mice. This abolished hepatocyte ballooning and apoptosis, substantially reduced steatosis and liver inflammation, and improved liver fibrosis. In vehicle-treated foz/foz mice, the mean nonalcoholic fatty liver disease activity score was 6.9, indicating NASH; MBX-8025 reversed NASH in all foz/foz mice (nonalcoholic fatty liver disease activity score 3.13). Conclusion: Seladelpar improves insulin sensitivity and reverses dyslipidemia and hepatic storage of lipotoxic lipids to improve NASH pathology in atherogenic diet-fed obese diabetic mice. Selective PPAR-δ agonists act independently of weight reduction, but counter lipotoxicity related to insulin resistance, thereby providing a novel therapy for NASH. (Hepatology Communications 2017;1:663-674).

A Randomized, Double-Blind, Active- and Placebo-Controlled Efficacy and Safety Study of Arhalofenate for Reducing Flare in Patients With Gout.

OBJECTIVE: Arhalofenate is a novel antiinflammatory uricosuric agent. The objective of this study was to evaluate its antiflare activity in patients with gout. METHODS: This was a 12-week, randomized, double-blind, controlled phase IIb study. Eligible patients had had ≥3 flares of gout during the previous year, had discontinued urate-lowering therapy and colchicine, and had a serum uric acid (UA) level of 7.5-12 mg/dl. Patients were randomly assigned at a 2:2:2:2:1 ratio to receive 600 mg arhalofenate, 800 mg arhalofenate, 300 mg allopurinol, 300 mg allopurinol plus 0.6 mg colchicine, or placebo once a day. The primary outcome measure was the flare incidence (number of flares divided by time of exposure). The serum UA level was a secondary outcome measure. RESULTS: A total of 239 gout patients were randomized and took at least 1 dose of study medication. The primary outcome measure comparing flare incidence between 800 mg arhalofenate and 300 mg allopurinol was achieved, with a 46% decrease in the 800 mg arhalofenate group (0.66 versus 1.24; P = 0.0056). Treatment with 800 mg arhalofenate was also significantly better than placebo (P = 0.049) and not significantly different from treatment with 300 mg allopurinol plus 0.6 mg colchicine (P = 0.091). Mean changes in serum UA level were -12.5% with 600 mg arhalofenate and -16.5% with 800 mg arhalofenate (P = 0.001 and P = 0.0001, respectively, versus -0.9% with placebo). There were no meaningful differences in adverse events (AEs) between groups, and there were no serious AEs related to arhalofenate. Urinary calculus occurred in 1 patient receiving 300 mg allopurinol. No abnormal serum creatinine values >1.5-fold the baseline value were observed in the arhalofenate-treated groups. CONCLUSION: Arhalofenate at a dosage of 800 mg decreased gout flares significantly compared to allopurinol at a dosage of 300 mg. Arhalofenate was well tolerated and appeared safe. Arhalofenate is the first urate-lowering antiflare therapy.

N-myristoylation of Arf proteins in Candida albicans: an in vivo assay for evaluating antifungal inhibitors of myristoyl-CoA: protein N-myristoyltransferase.

Myristoyl-CoA: protein N-myristoyltransferase (Nmt) catalyses the covalent attachment of myristate to the N-terminal glycine of a small subset of cellular proteins produced during vegetative growth of Candida albicans. nmt447D is a mutant NMT allele encoding an enzyme with a Gly447-->ASP substitution and reduced affinity for myristoyl-CoA. Among isogenic NMT/NMT, NMT/ delta nmt and nmt delta/nmt447D strains, only nmt delta/nmt447D cells require myristate for growth on yeast/peptone/dextrose media (YPD) at 24 or 37 degrees C. When switched from YPD/myristate to YPD alone, 60% of the organisms die with 4 h. Antibodies raised against the C-terminal eight residues of Saccharomyces cerevisiae Arf1p were used to probe Western blots of total cellular proteins prepared from these isogenic Candida strains. N-Myristoylation of C. albicans ADP-ribosylation factor (Arf) produced a change in its electrophoretic mobility during SDS-PAGE: the myristoylated species migrated more rapidly than the nonmyristoylated species. In an NMT/nmt delta strain, 100% of the Arf is N-myristoylated based on this mobility shift assay. When exponentially growing nmt delta/nmt447D cells were incubated at 24 degrees C in YPD/myristate, < 25% cellular Arf was nonmyristoylated. In contrast, 2 or 4 h after withdrawal of myristate, > or = 50% of total cellular Arf was nonmyristoylated. This finding suggests that > or = 50% reduction in Arf N-myristoylation is a biochemical marker of a growth-arrested cell. A similar conclusion was made after assaying isogenic S. cerevisiae strains containing various combinations of NMT1, nmt1-451D, ARF1, arf1 delta, ARF2 and arf2 delta alleles and grown at 24-37 degrees C on YPD of YPD/myristate. Peptidomimetic inhibitors of C. albicans Nmt were synthesized based on the N-terminal sequence of an S. cerevisiae Aft. SC-59383 has an IC50 of 1.45 +/- 0.08 microM for purified C. albicans Nmt and is 560-fold selective for the fungal compared to human N-myristoyltransferase. It had an EC50 of 51 +/- 17 and 67 +/- 6 microM, 24 and 48 h after a single administration of the drug to cultures of C. albicans. The Arf gel mobility shift assay indicated that a single dose of 200 microM produced a < 50% reduction in Arf N-myristoylation after 4 h, which is consistent with the fungistatic, but not fungicidal, activity. The effect on Nmt was specific: an enantiomer, SC-59840, had no inhibitory effect on purified C. albicans Nmt (IC50 > 1,000 microM), and 200 microM of the compound produced no detectable reduction in Arf N-myristoylation in vivo. SC-58272, which is related to SC-59383, was a more potent inhibitor in vitro (IC50 0.056 +/- 0.01 microM), but had no growth inhibitory activity and did not produce any detectable reduction in Arf N-myristoylation. These findings highlight the utility of the Arf protein gel mobility shift assay for demonstrating the mechanism-based antifungal activity of SC-59383, a selective inhibitor of C. albicans Nmt.