Investigation of pharmacokinetic drug interaction between clesacostat and DGAT2 inhibitor ervogastat in healthy adult participants.

Co-administration of clesacostat (acetyl-CoA carboxylase inhibitor, PF-05221304) and ervogastat (diacylglycerol O-acyltransferase inhibitor, PF-06865571) in laboratory models improved non-alcoholic fatty liver disease (NAFLD)/non-alcoholic steatohepatitis (NASH) end points and mitigated clesacostat-induced elevations in circulating triglycerides. Clesacostat is cleared via organic anion-transporting polypeptide-mediated hepatic uptake and cytochrome P450 family 3A (CYP3A); in vitro clesacostat is identified as a potential CYP3A time-dependent inactivator. In vitro ervogastat is identified as a substrate and potential inducer of CYP3A. Prior to longer-term efficacy trials in participants with NAFLD, safety and pharmacokinetics (PK) were evaluated in a phase I, non-randomized, open-label, fixed-sequence trial in healthy participants. In Cohort 1, participants (n = 7) received clesacostat 15 mg twice daily (b.i.d.) alone (Days 1-7) and co-administered with ervogastat 300 mg b.i.d. (Days 8-14). Mean systemic clesacostat exposures, when co-administered with ervogastat, decreased by 12% and 19%, based on maximum plasma drug concentration and area under the plasma drug concentration-time curve during the dosing interval, respectively. In Cohort 2, participants (n = 9) received ervogastat 300 mg b.i.d. alone (Days 1-7) and co-administered with clesacostat 15 mg b.i.d. (Days 8-14). There were no meaningful differences in systemic ervogastat exposures when administered alone or with clesacostat. Clesacostat 15 mg b.i.d. and ervogastat 300 mg b.i.d. co-administration was overall safe and well tolerated in healthy participants. Cumulative safety and no clinically meaningful PK drug interactions observed in this study supported co-administration of these two novel agents in additional studies exploring efficacy and safety in the management of NAFLD.

Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of PF-06817024 in Healthy Participants, Participants with Chronic Rhinosinusitis with Nasal Polyps, and Participants with Atopic Dermatitis: A Phase 1, Randomized, Double-Blind, Placebo-Controlled Study.

PF-06817024 is a high affinity, humanized antibody that binds interleukin-33, a proinflammatory type 2 cytokine, and thereby has the potential to inhibit downstream type 2 inflammation. This Phase 1, randomized, placebo-controlled study was conducted in 3 parts to evaluate the safety, tolerability, pharmacokinetics (PK), immunogenicity, and pharmacodynamics of escalating single and limited repeat PF-06817024 doses in healthy participants (Part 1), a single dose of PF-06817024 in participants with chronic rhinosinusitis with nasal polyps (Part 2), and repeat doses of PF-06817024 in participants with moderate to severe atopic dermatitis (atoptic dermatitis; Part 3). PF-06817024 was generally well tolerated in all participant populations. Most participants experienced a treatment-emergent adverse event (healthy participants, 78.4% and 100%; participants with chronic rhinosinusitis with nasal polyps, 90.9% and 88.9%; and participants with atoptic dermatitis, 60.0% and 62.5% in the PF-06817024 and placebo groups, respectively). No substantial deviations from dose proportionality were observed for single intravenous doses of 10-1000 mg, indicating linear PK in healthy participants. Mean terminal half-life ranged from 83 to 94 days after single intravenous administration in healthy participants and was similar to that observed after administration in the studied patient populations. Incidences of antidrug antibodies in the studied populations were 10.8%, 9.1%, and 5.0% for healthy participants, participants with chronic rhinosinusitis with nasal polyps, and participants with atoptic dermatitis, respectively. In addition, dose-dependent increases were observed in total serum interleukin-33 levels of treated participants, indicating target engagement. Overall, the PK and safety profile of PF-06817024 supports further investigation of the drug as a potential treatment for allergic diseases.

Investigating CNS distribution of PF-05212377, a P-glycoprotein substrate, by translation of 5-HT6 receptor occupancy from non-human primates to humans.

PF-05212377 (SAM760) is a potent and selective 5-HT6 antagonist, previously under development for the treatment of Alzheimer's disease. In vitro, PF-05212377 was determined to be a P-gp/non-BCRP human transporter substrate. Species differences were observed in the in vivo brain penetration of PF-05212377 with a ratio of the unbound concentration in brain/unbound concentration in plasma (Cbu /Cpu ) of 0.05 in rat and 0.64 in non-human primates (NHP). Based on pre-clinical evidence, brain penetration and target engagement of PF-05212377 was confirmed in NHP using positron emission tomography (PET) measured 5-HT6 receptor occupancy (%RO). The NHP Cpu EC50 of PF-05212377 was 0.31 nM (consistent with the in vitro human 5HT6 Ki : 0.32 nM). P-gp has been reported to be expressed in higher abundance at the rat BBB and in similar abundance at the BBB of non-human primates and human; brain penetration of PF-05212377 in humans was postulated to be similar to that in non-human primates. In humans, PF-05212377 demonstrated dose and concentration dependent increases in 5-HT6 RO; maximal 5-HT6 RO of ∼80% was measured in humans at doses of ≥15 mg with an estimated unbound plasma EC50 of 0.37 nM (which was similar to the in vitro human 5HT6 binding Ki 0.32 nM). In conclusion, cumulative evidence from NHP and human PET RO assessments confirmed that NHP is more appropriate than the rat for the prediction of human brain penetration of PF-05212377, a P-gp/non-BCRP substrate. Clinical trial number: NCT01258751.

ACC inhibitor alone or co-administered with a DGAT2 inhibitor in patients with non-alcoholic fatty liver disease: two parallel, placebo-controlled, randomized phase 2a trials.

Alterations in lipid metabolism might contribute to the pathogenesis of non-alcoholic fatty liver disease (NAFLD). However, no pharmacological agents are currently approved in the United States or the European Union for the treatment of NAFLD. Two parallel phase 2a studies investigated the effects of liver-directed ACC1/2 inhibition in adults with NAFLD. The first study ( NCT03248882 ) examined the effects of monotherapy with a novel ACC1/2 inhibitor, PF-05221304 (2, 10, 25 and 50 mg once daily (QD)), versus placebo at 16 weeks of treatment; the second study ( NCT03776175 ) investigated the effects of PF-05221304 (15 mg twice daily (BID)) co-administered with a DGAT2 inhibitor, PF-06865571 (300 mg BID), versus placebo after 6 weeks of treatment. The primary endpoint in both studies was percent change from baseline in liver fat assessed by magnetic resonance imaging-proton density fat fraction. Dose-dependent reductions in liver fat reached 50-65% with PF-05221304 monotherapy doses ≥10 mg QD; least squares mean (LSM) 80% confidence interval (CI) was -7.2 (-13.9, 0.0), -17.1 (-22.7, -11.1), -49.9 (-53.3, -46.2), -55.9 (-59.0, -52.4) and -64.8 (-67.5, -62.0) with 16 weeks placebo and PF-05221304 2, 10, 25 and 50 mg QD, respectively. The overall incidence of adverse events (AEs) did not increase with increasing PF-05221304 dose, except for a dose-dependent elevation in serum triglycerides (a known consequence of hepatic acetyl-coenzyme A carboxylase (ACC) inhibition) in 23/305 (8%) patients, leading to withdrawal in 13/305 (4%), and a dose-dependent elevation in other serum lipids. Co-administration of PF-05221304 and PF-06865571 lowered liver fat compared to placebo (placebo-adjusted LSM (90% CI) -44.6% (-54.8, -32.2)). Placebo-adjusted LSM (90% CI) reduction in liver fat was -44.5% (-55.0, -31.7) and -35.4% (-47.4, -20.7) after 6 weeks with PF-05221304 or PF-06865571 alone. AEs were reported for 10/28 (36%) patients after co-administered PF-05221304 and PF-06865571, with no discontinuations due to AEs, and the ACC inhibitor-mediated effect on serum triglycerides was mitigated, suggesting that PF-05221304 and PF-06865571 co-administration has the potential to address some of the limitations of ACC inhibition alone.

Efficacy and Safety of PF-06651600 (Ritlecitinib), a Novel JAK3/TEC Inhibitor, in Patients With Moderate-to-Severe Rheumatoid Arthritis and an Inadequate Response to Methotrexate.

OBJECTIVE: To evaluate the efficacy and safety of PF-06651600 (ritlecitinib), an irreversible inhibitor of JAK3 and the tyrosine kinase expressed in hepatocellular carcinoma (TEC) kinase family, in comparison with placebo in patients with rheumatoid arthritis (RA). METHODS: An 8-week, phase II, double-blind, parallel-group study was conducted. Seventy patients who were seropositive for anti-citrullinated protein antibodies and/or rheumatoid factor were randomized 3:2 to receive oral PF-06651600 (200 mg once daily) or placebo for 8 weeks. Eligible patients had an inadequate response to methotrexate, and the study design allowed up to 50% of patients to have previously received 1 tumor necrosis factor inhibitor that was inadequately effective and/or not tolerated. The primary end point was change from baseline in the Simplified Disease Activity Index (SDAI) score at week 8, assessed by Bayesian analysis using an informative prior distribution for placebo response. RESULTS: Mean change from baseline in the SDAI score at week 8 was greater in the PF-06651600 group (-26.1 [95% credible interval -29.7, -22.4]) than in the placebo group (-16.8 [95% credible interval -20.9, -12.7]; P < 0.001). Most adverse events (AEs) were mild in severity, and no treatment-related serious AEs, severe AEs, or deaths were reported. The most common classes of AE were infections and infestations as well as skin and subcutaneous tissue disorders; there was 1 mild case of herpes simplex in the PF-06651600 group that was considered to be treatment related, which resolved within 3 days without study treatment discontinuation or antiviral therapy. CONCLUSION: Treatment with the oral JAK3/TEC inhibitor PF-06651600 (200 mg once daily) was associated with significant improvements in RA disease activity and was generally well-tolerated in this small 8-week study.

Cancer Immunoprevention: A Case Report Raising the Possibility of "Immuno-interception".

Immune checkpoint blockade therapy provides substantial benefits for subsets of patients with advanced cancer, but its utility for cancer prevention is unknown. Lynch syndrome (MIM 120435) is characterized by defective DNA mismatch repair and predisposition to multiple cancers. A variant of Lynch syndrome, Muir-Torre syndrome (MIM 158320), is characterized by frequent gastrointestinal tumors and hyperplastic or neoplastic skin tumors. We report the case of a man with Muir-Torre syndrome who had 136 cutaneous or visceral hyperplastic or neoplastic lesions over a period of 19 years (mean 7.5 neoplasms/year, range 2-26) prior to receiving pembrolizumab immunotherapy as part of multi-modality treatment for invasive bladder cancer. He not only had a complete response of the bladder cancer, but also was noted to have an absence of new cancers during a 22-month follow-up period. This case adds to the rationale for exploring the utility of immune checkpoint blockade for cancer prevention, particularly for patients with DNA repair deficits.

Pharmacokinetic and Pharmacodynamic Effects of a γ-Secretase Modulator, PF-06648671, on CSF Amyloid-ß Peptides in Randomized Phase I Studies.

γ-Secretase modulators (GSMs) represent a promising therapy for Alzheimer's disease by reducing pathogenic amyloid-ß (Aß) peptide production. Three phase I studies (NCT02316756, NCT02407353, and NCT02440100) investigated the safety/tolerability, pharmacokinetics (PKs), and pharmacodynamics (PDs) of the oral GSM, PF-06648671. A PK/PD indirect-response model was developed (using biomarker data) to simultaneously characterize differential effects of PF-06648671 on multiple Aß species in cerebrospinal fluid (CSF). Healthy subjects (n = 120) received single doses or multiple-ascending doses of PF-06648671/placebo for 14 days. No serious adverse events occurred; severe adverse eventswere deemed not drug related. PF-06648671 decreased Aß42 and Aß40 concentrations in CSF, with greater effects on Aß42, and increased Aß37 and Aß38 levels, particularly Aß37. No significant change in total Aß was observed. The PK/PD model well described the tendency of observed CSF Aß data and the steady-state effects of PF-06648671, supporting its use for predicting central Aß effects and optimal dose selection for GSMs in future trials.

Safety, Tolerability, Pharmacokinetics, and Pharmacodynamic Effects of PF-06751979, a Potent and Selective Oral BACE1 Inhibitor: Results from Phase I Studies in Healthy Adults and Healthy Older Subjects.

PF-06751979 is a selective inhibitor of the beta-site amyloid precursor protein cleaving enzyme-1, which is a key aspartyl protease in the generation of amyloid-ß (Aß) peptides, thought to be critical for the cerebral degeneration observed in Alzheimer's disease. Two Phase I studies (NCT02509117, NCT02793232) investigated the safety/tolerability, pharmacokinetics (PK), and pharmacodynamics (PD) of PF-06751979. Single-ascending doses up to 540 mg and multiple-ascending doses up to 275 mg once daily (QD) in healthy adults, and multiple doses of 50 mg or 125 mg QD in healthy older subjects were assessed. PF-06751979 was well tolerated at all doses given, and all treatment-related adverse events (AEs) were mild to moderate. PK parameters remained consistent across the PF-06751979 QD dosing regimens, and no notable food effects were observed. PD analysis showed that PF-06751979 reduced the cerebrospinal fluid (CSF) and plasma levels of Aß peptides in a dose-dependent manner, with the greatest reductions observed in subjects treated with 275 mg QD (approximately 92% and 93% reduction in CSF Aß1-40 and Aß1-42 observed at 24 h after Day 14 dose, respectively). A drug interaction study (NCT03126721) using midazolam indicated that there was no clinically meaningful effect of multiple doses of PF-06751979 100 mg QD on the PK of single-dose midazolam in healthy adults. Overall, these data suggest that PF-06751979 with daily dosing is favorable for further clinical development.

Metabolism of a 5HT6 Antagonist, 2-Methyl-1-(Phenylsulfonyl)-4-(Piperazin-1-yl)-1H-Benzo[d]imidazole (SAM-760): Impact of Sulfonamide Metabolism on Diminution of a Ketoconazole-Mediated Clinical Drug-Drug Interaction.

SAM-760 [(2-methyl-1-(phenylsulfonyl)-4-(piperazin-1-yl)-1H-benzo[d]imidazole)], a 5HT6 antagonist, was investigated in humans for the treatment of Alzheimer's disease. In liver microsomes and recombinant cytochrome P450 (P450) isozymes, SAM-760 was predominantly metabolized by CYP3A (∼85%). Based on these observations and an expectation of a 5-fold magnitude of interaction with moderate to strong CYP3A inhibitors, a clinical DDI study was performed. In the presence of ketoconazole, the mean Cmax and area under the plasma concentration-time curve from time zero extrapolated to infinite time values of SAM-760 showed only a modest increase by 30% and 38%, respectively. In vitro investigation of this unexpectedly low interaction was undertaken using [14C]SAM-760. Radiometric profiling in human hepatocytes confirmed all oxidative metabolites previously observed with unlabeled SAM-760; however, the predominant radiometric peak was an unexpected polar metabolite that was insensitive to the pan-P450 inhibitor 1-aminobenzotriazole. In human hepatocytes, radiometric integration attributed 43% of the total metabolism of SAM-760 to this non-P450 pathway. Using an authentic standard, this predominant metabolite was confirmed as benzenesulfinic acid. Additional investigation revealed that the benzenesulfinic acid metabolite may be a novel, nonenzymatic, thiol-mediated reductive cleavage of an aryl sulfonamide group of SAM-760. We also determined the relative contribution of P450 to the metabolism of SAM-760 in human hepatocytes by following the rate of formation of oxidative metabolites in the presence and absence of P450 isoform-specific inhibitors. The P450-mediated oxidative metabolism of SAM-760 was still primarily attributed to CYP3A (33%), with minor contributions from P450 isoforms CYP2C19 and CYP2D6. Thus, the disposition of [14C]SAM-760 in human hepatocytes via novel sulfonamide metabolism and CYP3A verified the lower than expected clinical DDI when SAM-760 was coadministered with ketoconazole.

A Phase 2 clinical trial of PF-05212377 (SAM-760) in subjects with mild to moderate Alzheimer's disease with existing neuropsychiatric symptoms on a stable daily dose of donepezil.

BACKGROUND: Symptomatic benefits have been reported for 5-HT6 receptor antagonists in Alzheimer's disease (AD) trials. SAM-760 is a potent and selective 5-HT6 receptor antagonist that has demonstrated central 5-HT6 receptor saturation in humans at a dose of 30 mg. METHODS: This was a randomized, double-blind, placebo-controlled, parallel-group, multicenter trial evaluating the efficacy and safety of SAM-760 30 mg once daily (QD) for 12 weeks in subjects with AD on a stable regimen of donepezil 5 to 10 mg QD. The study included an interim analysis with stopping rules for futility or efficacy after 180 subjects completed the week 12 visit. Up to 342 subjects with AD (Mini-Mental State Examination (MMSE) score 10-24) and neuropsychiatric symptoms (Neuropsychiatric Inventory (NPI) total score ≥ 10) were to be enrolled if the study continued after the interim analysis. After a 4-week, single-blind, placebo run-in period, subjects entered the 12-week double-blind period and were randomized to either SAM-760 or placebo. The primary and key secondary efficacy endpoints were the change from baseline in Alzheimer's Disease Assessment Scale-cognitive subscale (ADAS-cog13) and NPI total scores. Mixed models for repeated measures were used to analyze the data. RESULTS: At the interim analysis, when 186 subjects had been randomized and 163 had completed the week 12 visit, the study met futility criteria and was stopped. The mean week 12 treatment difference was 0.70 points (P = 0.43) for ADAS-cog13 and 2.19 points (P = 0.20) for NPI score, both of which were numerically in favor of placebo. Other secondary endpoints did not demonstrate any significant benefit for SAM-760. In total, 46.2% of SAM-760 subjects reported adverse events (AE) versus 44.7% for placebo, and there were 5 (5.5%) serious AEs in the SAM-760 group versus 3 (3.2%) for placebo. There were two deaths, one prior to randomization and one in the SAM-760 group (due to a traffic accident during washout of active treatment). CONCLUSIONS: SAM-760 was safe and well tolerated, but there was no benefit of SAM-760 on measures of cognition, neuropsychiatric symptoms, or daily function. Differences in trial design, study population, region, or pharmacological profile may explain differences in outcome compared with other 5-HT6 receptor antagonists. TRIAL REGISTRATION: Clinicaltrials.gov, NCT01712074 . Registered 19 October 2012.

Prediction of Human Brain Penetration of P-glycoprotein and Breast Cancer Resistance Protein Substrates Using In Vitro Transporter Studies and Animal Models.

Four P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) substrates with human cerebrospinal fluid (CSF) concentrations and preclinical neuropharmacokinetics were used to assess in vitro-in vivo extrapolation of brain penetration in preclinical species and the ability to predict human brain penetration. Unbound brain (Cb,u), unbound plasma (Cp,u), and CSF compound concentrations (CCSF) were measured in rats and nonhuman primates (NHPs), and the unbound partition coefficients (Cb,u/Cp,u and CCSF/Cp,u) were used to assess brain penetration. The results indicated that for P-gp and BCRP dual substrates, brain penetration was severally impaired in all species. In comparison, for P-gp substrates that are weak or non-BCRP substrates, improved brain penetration was observed in NHPs and humans than in rats. Overall, NHP appears to be more predictive of human brain penetration for P-gp substrates with weak or no interaction with BCRP than rat. Although CCSF does not quantitatively correspond to Cb,u for efflux transporter substrates, it is mostly within 3-fold higher of Cb,u in rat and NHP, suggesting that CCSF can be used as a surrogate for Cb,u. Taken together, a holistic approach including both in vitro transporter and in vivo neuropharmacokinetics data enables a better estimation of human brain penetration of P-gp/BCRP substrates.

Discovery and Characterization of (R)-6-Neopentyl-2-(pyridin-2-ylmethoxy)-6,7-dihydropyrimido[2,1-c][1,4]oxazin-4(9H)-one (PF-06462894), an Alkyne-Lacking Metabotropic Glutamate Receptor 5 Negative Allosteric Modulator Profiled in both Rat and Nonhuman Primates.

We previously observed a cutaneous type IV immune response in nonhuman primates (NHP) with the mGlu5 negative allosteric modulator (NAM) 7. To determine if this adverse event was chemotype- or mechanism-based, we evaluated a distinct series of mGlu5 NAMs. Increasing the sp3 character of high-throughput screening hit 40 afforded a novel morpholinopyrimidone mGlu5 NAM series. Its prototype, (R)-6-neopentyl-2-(pyridin-2-ylmethoxy)-6,7-dihydropyrimido[2,1-c][1,4]oxazin-4(9H)-one (PF-06462894, 8), possessed favorable properties and a predicted low clinical dose (2 mg twice daily). Compound 8 did not show any evidence of immune activation in a mouse drug allergy model. Additionally, plasma samples from toxicology studies confirmed that 8 did not form any reactive metabolites. However, 8 caused the identical microscopic skin lesions in NHPs found with 7, albeit with lower severity. Holistically, this work supports the hypothesis that this unique toxicity may be mechanism-based although additional work is required to confirm this and determine clinical relevance.

Assessment of Cognitive and Neurologic Recovery in Ischemic Stroke Drug Trials: Results from a Randomized, Double-blind, Placebo-controlled Study.

Objective. Ischemic stroke is a serious medical condition with limited therapeutic options. The evaluation of the therapeutic potential of novel pharmacological interventions is carried-out in Phase II trials. The study design, primarily intended to evaluate efficacy and safety, is a balance between utilizing as few patients as possible to minimize safety risk and enrolling sufficient patients to detect unambiguous efficacy signals. We sought to determine whether post-stroke recovery outcomes based on behavioral measures of cognitive and motor impairment yielded additional information beyond that of clinician-based methods. Design. This was a multicenter, multinational, randomized, parallel group, controlled versus placebo, efficacy, and safety study of PF-03049423 for treatment of acute ischemic stroke. Settings and participants. Our study subjects were acute ischemic stroke inpatients. Measurements. Outcome measures were derived from rating scales (Modified Rankin Scale, Barthel Index, and National Institutes of Health Stroke Scale) and behavioral tests (Box and Blocks Test, Hand Grip Strength Test, 10-Meter Walk Test, Repeatable Battery Assessment of Neuropsychological Status Naming and Coding Subtests, Line Cancellation Test, and Recognition Memory Test). Assessments were performed at Days 7, 14, 30, 60, and 90. Post-hoc analyses of correlations among the outcome measures at each measurement time point on a cohort of 137 subjects were conducted. Results. Results support the validity of measures from Box and Blocks Test, Hand Grip Strength Test, 10-Meter Walk Test, and Repeatable Battery Assessment of Neuropsychological Status Coding Subtests to monitor post-stroke recovery in clinical trial settings. Notably, the Recognition Memory Test did not show a correlation with the Modified Rankin Scale, and, in fact, did not show improvement over time. Conclusion. The behavioral measures of cognitive and motor functions included in this study may extend the evaluation of the therapeutic potential of new treatments for stroke recovery. The lack of correlation between Recognition Memory Test and the traditional efficacy endpoints, at least in part due to absence of any improvement in recognition memory, suggests that there may be cognitive elements not detected by the Modified Rankin Scale. This is clinically relevant and memory improvement has potential as an endpoint in future trials aiming to improve certain aspects of cognition.

Phosphodiesterase-5 Inhibitor PF-03049423 Effect on Stroke Recovery: A Double-Blind, Placebo-Controlled Randomized Clinical Trial.

BACKGROUND: The therapeutic potential of phosphodiesterase-5 inhibitor PF-03049423 was evaluated in a phase 2, multicenter, randomized, double-blind, placebo-controlled study of subjects with acute ischemic stroke ( CLINICAL TRIAL REGISTRATION INFORMATION: http://www.clinicaltrials.gov, unique identifier: NCT01208233; http://www.clinicaltrialsregister.eu, EudraCT number: 2010-021414-32). MATERIALS AND METHODS: Subjects (N = 70) received PF-03049423 6 mg (or placebo, N = 67) once daily, orally, commencing between 24 and 78 hours of stroke onset, and continuing for 90 days. Postbaseline efficacy assessments were performed on Days 7, 14, 30, 60, and 90. Modified Rankin Scale (mRS), Barthel Index, National Institutes of Health Stroke Scale, Box and Blocks Test, Hand-Grip Strength Test, 10-Meter Walk Test, Repeatable Battery Assessment of Neuropsychological Status Naming and Coding Subtests, Line Cancellation Test, and Recognition Memory Test were administered to evaluate poststroke recovery. The primary endpoint was the mRS responder rate (score 0-2 at Day 90). The study included a planned interim analysis of efficacy data. RESULTS: The primary efficacy analysis using logistic regression showed no statistically significant difference between PF-03049423 6 mg and placebo (responder rate of 42.6% and 46.2%, respectively). Although PF-03049423 showed a satisfactory safety and tolerability profile, no signal of efficacy emerged from any of the outcome measures. CONCLUSIONS: PF-03049423 showed no therapeutic potential for acute ischemic stroke.

Clinical trial of an inhibitor of RAGE-Aß interactions in Alzheimer disease.

OBJECTIVE: To examine safety, tolerability, and efficacy of PF-04494700, an inhibitor of the receptor for advanced glycation end products (RAGE), in mild to moderate Alzheimer disease (AD). METHODS: Double-blind, placebo-controlled trial at 40 academic centers (United States). Subjects with AD and Mini-Mental State Examination score 14-26 were randomized to PF-04494700 60 mg/day × 6 days, then 20 mg daily (high dose); 15 mg/day × 6 days, then 5 mg daily (low dose); or placebo, for 18 months. Clinical and laboratory measures were used to evaluate safety and tolerability. The primary efficacy measure was the Alzheimer's Disease Assessment Scale-cognitive (ADAS-cog). Secondary measures assessed clinical stage, function, behavior, MRI, and CSF biomarkers. RESULTS: A total of 399 subjects were randomized. In a prespecified interim analysis, when 50% of subjects had completed the 6-month visit, the high dose was associated with confusion, falls, and greater ADAS-cog decline and was discontinued. A second prespecified analysis compared low-dose and placebo groups for futility and safety approximately 12 months after all subjects were randomized. This analysis met criteria for futility, and treatment was discontinued. There were no safety concerns in the low-dose group. Analyses including post-futility data showed decreased decline on the ADAS-cog in the low-dose group at month 18. Other clinical and biomarker measures showed no differences between low-dose treatment and placebo. CONCLUSIONS: PF-04494700 at 20 mg/d was associated with increased adverse events and cognitive decline. At 5 mg/d, PF-04494700 had a good safety profile. A potential benefit for this low dose on the ADAS-cog is not conclusive, because of high dropout and discontinuation rates subsequent to the interim analyses. CLASSIFICATION OF EVIDENCE: This study provides Class I evidence that in patients with AD high-dose PF-04494700 increased cognitive decline at 6 months and Class IV evidence that low-dose PF-04494700 slowed cognitive decline at 18 months.

Diphenhydramine has similar interspecies net active influx at the blood-brain barrier.

In rats, oxycodone, diphenhydramine, and [4-chloro-5-fluoro-2-(3-methoxy-2-methyl-phenoxy)-benzyl]-methylamine (CE-157119) undergo net active influx at the blood-brain barrier (BBB) based on significantly greater interstitial fluid compound concentrations (CISF ) than unbound plasma compound concentrations (Cp,u ). Oxycodone and diphenhydramine have CISF :Cp,u of 3.0 and 5.5, respectively, while CE-157119 has an unbound brain compound concentration (Cb,u ):Cp,u of 3.90; Cb,u is a high-confidence CISF surrogate. However, only CE-157119 has published dog and nonhuman primate (nhp) neuropharmacokinetics, which show similar Cb,u :Cp,u (4.61 and 2.04, respectively) as rats. Thus, diphenhydramine underwent identical interspecies neuropharmacokinetics studies to determine if its net active BBB influx in rats replicated in dogs and/or nhp. The single-dose-derived rat Cb,u :Cp,u (3.90) was consistent with prior steady-state-derived CISF :Cp,u and similar to those in dogs (4.88) and nhp (4.51-5.00). All large animal interneurocompartmental ratios were ≤1.8-fold different than their rat values, implying that diphenhydramine has constant and substantial Cb,u -favoring disequilibria in these mammals. Accordingly, the applied Cb,u -forecasting methodology accurately predicted [estimated mean (95% confidence interval) of 0.84 (0.68, 1.05)] Cb,u from each measured Cp,u in large animals. The collective datasets suggest these Cb,u -preferring asymmetries are mediated by a species-independent BBB active uptake system whose identification, full characterization, and structure-activity relationships should be prioritized for potential exploitation.

Discovery and preclinical characterization of 1-methyl-3-(4-methylpyridin-3-yl)-6-(pyridin-2-ylmethoxy)-1H-pyrazolo-[3,4-b]pyrazine (PF470): a highly potent, selective, and efficacious metabotropic glutamate receptor 5 (mGluR5) negative allosteric modulator.

A novel series of pyrazolopyrazines is herein disclosed as mGluR5 negative allosteric modulators (NAMs). Starting from a high-throughput screen (HTS) hit (1), a systematic structure-activity relationship (SAR) study was conducted with a specific focus on balancing pharmacological potency with physicochemical and pharmacokinetic (PK) properties. This effort led to the discovery of 1-methyl-3-(4-methylpyridin-3-yl)-6-(pyridin-2-ylmethoxy)-1H-pyrazolo[3,4-b]pyrazine (PF470, 14) as a highly potent, selective, and orally bioavailable mGluR5 NAM. Compound 14 demonstrated robust efficacy in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-rendered Parkinsonian nonhuman primate model of l-DOPA-induced dyskinesia (PD-LID). However, the progression of 14 to the clinic was terminated because of a potentially mechanism-mediated finding consistent with a delayed-type immune-mediated type IV hypersensitivity in a 90-day NHP regulatory toxicology study.

An evaluation of using rat-derived single-dose neuropharmacokinetic parameters to project accurately large animal unbound brain drug concentrations.

Previous publications suggest that interstitial fluid compound concentrations (C(ISF)) best determine quantitative neurotherapeutic pharmacology relationships, although confirming large animal C(ISF) remains elusive. Therefore, this work primarily evaluated using respective acute dose, rat-derived unbound brain compound concentration-to-unbound plasma compound concentration ratios (C(b,u)/C(p,u)) to project accurately dog and nonhuman primate (nhp) C(b,u), a C(ISF) surrogate, from measured C(p,u) for the highly permeable non-P-glycoprotein substrates N-{(3R,4S)-3-[4-(5-cyano-2-thienyl)phenyl]tetrahydro-2H-pyran-4-yl}propane-2-sulfonamide (PF-4778574) and [4-chloro-5-fluoro-2-(3-methoxy-2-methyl-phenoxy)-benzyl]-methylamine (CE-157119) and the P-glycoprotein substrates risperidone and 9-hydroxyrisperidone. First, in rats, it was determined for eight of nine commercial compounds that their single-dose-derived C(b,u)/C(p,u) were ≤2.5-fold different from their steady-state values; for all nine drugs, their C(b,u)/C(p,u) were ≤2.5-fold different from their steady-state C(ISF)/C(p,u) (Drug Metab Dispos 37:787-793, 2009). Subsequently, PF-4778574, CE-157119 and risperidone underwent rat, dog, and nhp neuropharmacokinetics studies. In large animals at each measured C(p,u), the methodology adequately predicted [estimated mean (95% confidence interval) of 1.02 (0.80, 1.29)] the observed C(b,u) for PF-4778574 and CE-157119 but underpredicted [0.17 (0.12, 0.22)] C(b,u) for risperidone and 9-hydroxyrisperidone. The data imply that forecasting higher species C(b,u) from a measured C(p,u) and rat acute dose-determined C(b,u):C(p,u) is of high confidence for nonefflux transporter substrates that show net passive diffusion (PF-4778574) or net active influx (CE-157119) at the blood-brain barrier in rats. However, this methodology appears ineffective for correctly predicting large animal C(b,u) for P-glycoprotein substrates (risperidone and 9-hydroxyrisperidone) because of their apparently much greater C(p,u)-favoring C(b,u):C(p,u) asymmetry in rats versus dogs or nhp. Instead, for such P-glycoprotein substrates, large animal-specific cerebrospinal fluid compound concentrations (C(CSF)) seemingly best represent C(b,u).

Age-adjusted exact trend tests in the event of rare occurrences.

Preclinical animal carcinogenicity studies are usually concerned with testing the statistical significance of a dose-response relationship. When the response consists of a rare event such as the development of a certain type of tumor, exact statistical methods are often employed. The exact randomization trend test based on the multivariate hypergeometric distribution is less powerful in the presence of treatment-related risks other than the specified response. Particularly, the loss of power becomes more pronounced when competing risks cause progressively higher mortality rates with increasing dose, which is usual in practice. An age-adjusted form of the randomization test is proposed to adjust for this effect. Permutational distribution for Peto's cause-of-death (COD) test is also explored and compared with its asymptotic counterpart by simulation. The use of COD information has been a controversial issue due to the subjectivity in the pathologists' determinations as well as for economic reasons. The proposed age-adjusted exact test does not require COD, and it is shown to compare favorably to the COD tests via an extensive Monte Carlo simulation. Applications of the methods to two real data sets are included.