Therapeutic peptides for CNS indications: Progress and challenges.

Attacking neurodegeneration and promoting neuroprotection have been the holy grail in neurology for almost 20years and represent an area of high unmet medical need. However, indications like Alzheimer's disease and stroke are areas in drug development fraught with failure. This review will highlight three CNS peptide programs which are tackling targets and indications in which traditional small molecule approaches have been difficult and challenging. The targets for these potential peptide therapeutics include the NMDA receptor, γ-secretase, and cyclin-dependent kinase in which direct inhibition has resulted in on-target (not compound related) problems. For example, direct inhibition of γ-secretase has resulted in gastrointestinal abnormalities and inhibition of the NMDA receptor can result in hallucinations, dizziness, out-of-body sensations, and nightmares. When confronted with show-stopping side effects, the CNS peptide programs profiled in this review strike the problem with intervention and disruption of selective protein-protein interactions. The goal of these peptide programs is to produce selective therapeutics with a better safety profile.

Safety Pharmacology in Drug Discovery and Development.

Safety pharmacology is essential throughout the spectrum of drug discovery and development. Prior to first-in-human studies, safety pharmacology assays, tests, and models predict the clinical risk profile of a potential new drug. During clinical development, safety pharmacology can be used to explore--and potentially explain--both predicted and unpredicted side effects (e.g., adverse events, changes in vital signs, abnormal laboratory values) in order to refine the original clinical risk profile. This chapter will introduce the reader to safety pharmacology's role in translational medicine: the science of translating potential drugs' on- and off-target nonclinical properties to clinical consequences in order to select the best drug candidates to move into early clinical testing. Case studies will be used to illustrate the importance of safety pharmacology testing throughout all phases of drug development.

A double-blind, placebo-controlled, ascending-dose, randomized study to evaluate the safety, tolerability and effects on cognition of AL-108 after 12 weeks of intranasal administration in subjects with mild cognitive impairment.

BACKGROUND/AIMS: AL-108-211 was a placebo-controlled, ascending-dose study that explored the safety, tolerability and efficacy of 12 weeks of treatment with AL-108 in subjects with amnestic mild cognitive impairment. METHODS: A total of 144 subjects were randomized in a 2:1 drug:placebo ratio. Subjects were enrolled into the low-dose group or placebo and then to the high-dose group or placebo. Pooling of the placebo groups yielded 3 groups (approx. 48/group) whose baseline demographics and disease characteristics were well matched. RESULTS: AL-108 was generally safe and well tolerated. Analyses of efficacy data failed to detect a statistically significant difference between the treatment groups on the composite cognitive memory score. Analyses of the individual cognitive tasks identified signals of potential efficacy in 2 tests of memory and attention. CONCLUSION: These data suggest that AL-108 was generally safe, well tolerated and merits additional investigation as a treatment for Alzheimer's disease.

Revision of the criteria for Alzheimer's disease: A symposium.

The current criteria for classification of Alzheimer's disease (AD) have deficiencies that limit drug development, research, and practice. The current standard for the clinical diagnosis of AD, the National Institute of Neurological and Communicative Disorders and Stroke (now known as the National Institute of Neurological Disorders and Stroke), and the Alzheimer's Disease and Related Disorders Association (now known as the Alzheimer's Association) criteria, are nearly 25 years old and have not been revised to incorporate advances in the epidemiology and genetics of AD, studies of clinicopathologic correlations and recent studies of potential diagnostic biomarkers. In a very real sense our ability to diagnose AD with a very high level of certainty has outpaced our current diagnostic criteria. The Alzheimer's Association Research Roundtable convened a meeting in April 2009 to discuss new data and technologies that could, with further development, enable improvements in the clinical diagnosis of AD, especially in its earliest and mildest stages. This meeting reviewed the current standards for detecting and defining the clinical presentation of AD and discussed areas that could contribute to earlier and more accurate definitive clinical diagnosis. These included clinical, neuropsychological, and other performance-based assessments, genetic contributions, and biochemical and neuroimaging biomarkers that could reflect AD pathology and lead to better ascertainment of AD, mild cognitive impairment, and presymptomatic AD.

A Placebo-Controlled, Parallel-Group, Randomized Clinical Trial of AC-1204 in Mild-to-Moderate Alzheimer's Disease.

BACKGROUND: Alzheimer's disease (AD) is characterized by amyloid-ß plaques, neurofibrillary tangles, and regional cerebral glucose hypometabolism. Providing an alternative metabolic substrate, such as ketone bodies, may be a viable therapeutic option. OBJECTIVE: The objective was to determine the efficacy and safety of the AC-1204 formulation of caprylic triglyceride administered daily for 26 weeks in APOE4 non-carrier participants with mild-to-moderate AD. METHODS: In a double-blind, placebo-controlled, randomized study (AC-12-010, NOURISH AD, NCT01741194), 413 patients with mild-to-moderate probable AD were stratified by APOE genotype and randomized (1 : 1) to receive either placebo or AC-1204 for 26 weeks. The primary outcome was the change from baseline to week 26 on the 11-item Alzheimer's Disease Assessment Scale - Cognitive subscale (ADAS-Cog11) among APOE4 non-carriers. The key secondary outcome was the change from baseline to week 26 in the Alzheimer's Disease Cooperative Study - Clinician's Global Impression of Change scale. RESULTS: Administration of AC-1204 was safe and well-tolerated. Mean changes from baseline in the primary outcome at 26 weeks in ADAS-Cog11 for placebo (n = 138) was 0.0 and for AC-1204 (n = 137) was 0.6 (LS differences of mean - 0.761, p = 0.2458) and secondary outcome measures failed to detect any drug effects. CONCLUSION: The AC-1204 formulation of caprylic triglyceride failed to improve cognition or functional ability in subjects with mild-to-moderate AD. The lack of efficacy observed in this study may have several contributing factors including a lower ketone body formation from AC-1204 than expected and a lack of decline in the patients receiving placebo.

Translatability of the S7A core battery respiratory safety pharmacology studies: Preclinical respiratory and related clinical adverse events.

INTRODUCTION: Before entering into first-in-human studies, most new chemical entities must undergo a series of preclinical evaluations. ICH S7A safety pharmacology (SP) guidelines, adopted in 2001, include respiratory assessments as part of the core battery. Despite these safety measures being in place for nearly two decades, studies examining the relationship between preclinical findings captured in respiratory SP studies and clinical respiratory adverse events (AEs) are sparse. Therefore, the aim of this study is to evaluate the predictive value of preclinical respiratory observations to identify clinical respiratory AEs for both investigational products in early drug development and approved drugs. METHOD: Three independent databases were interrogated to evaluate the concordance between preclinical and clinical respiratory AEs. Two databases stem from early clinical phase studies, evaluating 52 and 128 investigational products respectively. The third database was derived from a large repository of nearly 4000 FDA and EMA drug approval documents. RESULTS: Analysis of early phase clinical studies revealed little to no predictive risk for clinical respiratory adverse events when respiratory findings were observed in preclinical studies, with a positive predictive value (PPV) of 27% and 36% for each dataset respectively. In addition, the likelihood ratio, which reflects the shift in predictability of human risk, was 1.02 and 0.76 respectively, indicating no change in liability. Evaluation of approved drugs revealed a small shift in predictability for preclinical respiratory findings to translate into respiratory clinical AE, with likelihood ratios ranging from 2.5-3.4 and PPV of 18-29% for severe AEs such as lung disorder, respiratory depression and respiratory failure. DISCUSSION: Altogether the translatability of preclinical respiratory findings into clinical AEs is low. Mandating dedicated respiratory SP studies as part of the core battery should be reconsidered in light of the low translatability of respiratory risk clinically and can be effectively incorporated into toxicology investigations.

Evaluating cardiac risk: exposure response analysis in early clinical drug development.

The assessment of a drug's cardiac liability has undergone considerable metamorphosis by regulators since International Council for Harmonization of Technical Requirement for Pharmaceuticals for Human Use E14 guideline was introduced in 2005. Drug developers now have a choice in how proarrhythmia risk can be evaluated; the options include a dedicated thorough QT (TQT) study or exposure response (ER) modeling of intensive electrocardiogram (ECG) captured in early clinical development. The alternative approach of ER modeling was incorporated into a guidance document in 2015 as a primary analysis tool which could be utilized in early phase dose escalation studies as an option to perform a dedicated TQT trial. This review will describe the current state of ER modeling of intensive ECG data collected during early clinical drug development; the requirements with regard to the use of a positive control; and address the challenges and opportunities of this alternative approach to assessing QT liability.

Tracking the Sugar Rush: Incorporating Continuous Glucose Monitoring Into Multisite Early Clinical Research With Type 2 Diabetes Subjects.

Continuous glucose monitoring (CGM) systems allow patients with diabetes mellitus to closely track glucose concentrations over several days, identify trends in glucose levels, and avoid glucose excursions. This technology has not only advanced diabetes mellitus management but has increased patient safety through greater glycemic awareness. Due to these attributes, CGM is now being applied in therapeutic research as a pharmacodynamic tool to support early clinical drug development programs. However, to date only a handful of studies have utilized CGM in type 2 diabetes mellitus (T2DM) drug development. A potential barrier from fostering greater use of CGM in clinical development may be related to concerns over subject variability. Therefore, we investigated a key consideration when implementing CGM into early clinical research studies: daily variation within patients with T2DM from multiple clinical research units. From 24 patients with T2DM, we observed strong daily reproducibility (Pearson R = 0.86, P < .0001) in CGM results and found that this technique is practical for multisite studies. Altogether, with low daily variability, CGM is a powerful pharmacodynamic tool for drug efficacy and safety monitoring.

Pharmacokinetics in Rat of P8, a Peptide Drug Candidate for the Treatment of Alzheimer's Disease: Stability and Delivery to the Brain.

Strategies to achieve a therapy for Alzheimer's disease (AD) aimed at reducing the effects of amyloid-ß (Aß) have largely involved inhibiting or modifying the activities of the ß- or γ-secretases or by the use of monoclonal antibodies (MAb). We previously offered the potential for a new, early and effective approach for the treatment of AD by a strategy that does not target the secretases. We showed that a family of peptides containing the DEEEDEEL sequence and another independent peptide, all derived from the amino terminus of PS-1, are each capable of markedly reducing the production of Aß in vitro and in mThy1-hAPP transgenic mice. These peptides gave a strong and specific binding with the ectodomain of amyloid-ß protein precursor (AßPP) and did not affect the catalytic activities of ß- or γ-secretase, or the level of AßPP. Critical to the development of any therapeutic for AD is the requirement that it is stable and can be delivered to the brain. We report here data on the metabolic stability and delivery to the rat brain of our lead candidate P8 by intravenous (IV), intranasal (IN), and subcutaneous (SC) administration. Pharmacokinetics (PK) of P8 in rat plasma and CSF following a single dose of P8 demonstrate that SC administration gives better absorption compared to IN and is the delivery method of choice for the further development of P8 as a clinical candidate.

Update and trends on pharmacokinetic studies in patients with impaired renal function: practical insight into application of the FDA and EMA guidelines.

INTRODUCTION: The incidence of kidney dysfunction increases with age and is highly prevalent among patients with hypertension. Since many therapeutic compounds are primarily eliminated through the kidneys, impaired renal function can have negative consequences on drug disposition, efficacy and safety. Therefore, regulatory agencies such as the Food and Drug Administration (FDA) and European Medicines Agency (EMA) have issued detailed guidelines for new drug applications to determine posology requirements for patients with renal impairment. Areas covered: The current review highlights and contrasts agency requirements for pharmacokinetic renal impairment clinical studies. While many of the guidelines are similar among the two agencies, glomerular filtration rate (GFR) determination and reporting differ. Design considerations for a reduced, full or dialysis renal impairment study, as well as modifications to the FDA's draft guidance are discussed. Furthermore, scenarios where pharmacokinetic modelling analysis can benefit a drug development program are also reviewed. Moreover, practical solutions for patient recruitment challenges are addressed. Expert commentary: We summarize how 'one size does not fit all' for GFR assessment, and recommend when to use certain modalities. Finally, we highlight the need for the pharmaceutical industry to engage therapeutic experts to assist in protocol development for renal impairment studies, as these experts understand the nuances of this special population and recommended guidelines.

Predicting disease progression in progressive supranuclear palsy in multicenter clinical trials.

INTRODUCTION: Clinical and MRI measurements can track disease progression in PSP, but many have not been extensively evaluated in multicenter clinical trials. We identified optimal measures to capture clinical decline and predict disease progression in multicenter PSP trials. METHODS: Longitudinal clinical rating scales, neuropsychological test scores, and volumetric MRI data from an international, phase 2/3 clinical trial of davunetide for PSP (intent to treat population, n = 303) were used to identify measurements with largest effect size, strongest correlation with clinical change, and best ability to predict dropout or clinical decline over one year as measured by PSP Rating Scale (PSPRS). RESULTS: Baseline cognition as measured by Repeatable Battery for Assessing Neuropsychological Status (RBANS) was associated with attrition, but had only a small effect. PSPRS and Clinical Global Impression (CGI) had the largest effect size for measuring change. Annual change in CGI, RBANS, color trails, and MRI midbrain and ventricular volumes were most strongly correlated with annual PSPRS and had the largest effect sizes for detecting annual change. At baseline, shorter disease duration, more severe depression, and lower performance on RBANS and executive function tests were associated with faster worsening of the PSPRS in completers. With dropouts included, SEADL, RBANS, and executive function tests had significant effect on PSPRS trajectory of change. CONCLUSION: Baseline cognitive status and mood influence the rate of disease progression in PSP. Multiple clinical, neuropsychological, and volumetric MRI measurements are sensitive to change over one year in PSP and appropriate for use in multicenter clinical trials.

Intranasal NAP (davunetide) decreases tau hyperphosphorylation and moderately improves behavioral deficits in mice overexpressing α-synuclein.

Genome-wide association studies have identified strong associations between the risk of developing Parkinson's disease (PD) and polymorphisms in the genes encoding α-synuclein and the microtubule-associated protein tau. However, the contribution of tau and its phosphorylated form (p-tau) to α-synuclein-induced pathology and neuronal dysfunction remains controversial. We have assessed the effects of NAP (davunetide), an eight-amino acid peptide that decreases tau hyperphosphorylation, in mice overexpressing wild-type human α-synuclein (Thy1-aSyn mice), a model that recapitulates aspects of PD. We found that the p-tau/tau level increased in a subcortical tissue block that includes the striatum and brain stem, and in the cerebellum of the Thy1-aSyn mice compared to nontransgenic controls. Intermittent intranasal NAP administration at 2 µg/mouse per day, 5 days a week, for 24 weeks, starting at 4 weeks of age, significantly decreased the ratio of p-tau/tau levels in the subcortical region while a higher dose of 15 µg/mouse per day induced a decrease in p-tau/tau levels in the cerebellum. Both NAP doses reduced hyperactivity, improved habituation to a novel environment, and reduced olfactory deficits in the Thy1-aSyn mice, but neither dose improved the severe deficits of motor coordination observed on the challenging beam and pole, contrasting with previous data obtained with continuous daily administration of the drug. The data reveal novel effects of NAP on brain p-tau/tau and behavioral outcomes in this model of synucleinopathy and suggest that sustained exposure to NAP may be necessary for maximal benefits.

Davunetide in patients with progressive supranuclear palsy: a randomised, double-blind, placebo-controlled phase 2/3 trial.

BACKGROUND: In preclinical studies, davunetide promoted microtubule stability and reduced tau phosphorylation. Because progressive supranuclear palsy (PSP) is linked to tau pathology, davunetide could be a treatment for PSP. We assessed the safety and efficacy of davunetide in patients with PSP. METHODS: In a double-blind, parallel group, phase 2/3 trial, participants were randomly assigned with permuted blocks in a 1:1 ratio to davunetide (30 mg twice daily, intranasally) or placebo for 52 weeks at 48 centres in Australia, Canada, France, Germany, the UK, and the USA. Participants met the modified Neuroprotection and Natural History in Parkinson Plus Syndrome study criteria for PSP. Primary endpoints were the change from baseline in PSP Rating Scale (PSPRS) and Schwab and England Activities of Daily Living (SEADL) scale at up to 52 weeks. All participants and study personnel were masked to treatment assignment. Analysis was by intention to treat. The trial is registered with Clinicaltrials.gov, number NCT01110720. FINDINGS: 313 participants were randomly assigned to davunetide (n=157) or to placebo (n=156), and 241 (77%) completed the study (118 and 156 in the davunetide and placebo groups, respectively). There were no differences in the davunetide and placebo groups in the baseline PSPRS and SEADL. The davunetide and placebo groups did not differ in the change from baseline in PSPRS (median 11·8 [95% CI 10·5 to 13·0] vs 11·8 [10·5 to 13·0], respectively, p=0·41) or SEADL (-0·20 [-0·20 to -0·17] vs -0·20 [-0·22 to -0·17], respectively, p=0·92). 54 serious adverse events were reported in each of the treatment groups, including 11 deaths in the davunetide group and ten in the placebo group. The frequency of nasal adverse events was greater in the davunetide group than in the placebo group (epistaxis 18 [12%] of 156 vs 13 [8%] of 156, rhinorrhoea 15 [10%] vs eight [5%], and nasal discomfort 15 [10%] vs one [<1%]). INTERPRETATION: Davunetide is not an effective treatment for PSP. Clinical trials of disease-modifying treatment are feasible in patients with PSP and should be pursued with other promising tau-directed treatments. FUNDING: Allon Therapeutics.

Davunetide: a review of safety and efficacy data with a focus on neurodegenerative diseases.

Davunetide is the first neuroprotective peptide in its class, and has preclinical evidence for neuroprotective, neurotrophic and cognitive protective properties. Davunetide has also been shown to prevent apoptosis or programmed-cell death in a range of in vitro and in vivo models by promoting microtubule stabilization. Potential clinical uses of davunetide include neurodegenerative disorders such as Alzheimer's disease (AD), progressive supranuclear palsy (PSP), frontotemporal dementia (FTD) or cognitive impairment in other diseases such as schizophrenia where microtubule structure and function is known to be impaired. The nonclinical and clinical safety of davunetide is reviewed here in detail. Pre-clinical toxicology studies in rats and dogs using the maximum feasible dose of davunetide provide strong evidence that davunetide is well-tolerated. Similarly, data from 10 separate clinical trials of davunetide, investigating safety and efficacy provide evidence that davunetide is generally safe and well-tolerated, and has shown some signs of clinical efficacy.

Drug development of intranasally delivered peptides.

Intranasal drug delivery has attracted increasing attention as a noninvasive route of administration for therapeutic proteins and peptides. The delivery of therapeutic peptides through the nasal route provides an alternative to intravenous or subcutaneous injections. This review highlights the drug-development considerations unique to nasal therapeutics and discusses some of the factors and strategies that affect and can improve nasal absorption of peptides. The selectivity and good safety profile typical of peptide therapeutics, along with the dose limitation for intranasal administration, can provide challenges in drug development. Therefore, nasal peptide therapeutics often require special considerations in the nonclinical safety evaluations, such as determining drug exposure in the context of the maximum feasible dose in order to adequately prepare nasal products for clinical studies.

Critical appraisal of the role of davunetide in the treatment of progressive supranuclear palsy.

Progressive supranuclear palsy (PSP) is a rare neurodegenerative disease characterized by the accumulation of tau protein aggregates in the basal ganglia, brainstem and cerebral cortex leading to rapid disease progression and death. The neurofibrillary tangles that define the neuropathology of PSP are comprised of aggregated 4R tau and show a well-defined distribution. Classically, PSP is diagnosed by symptoms that include progressive gait disturbance, early falls, vertical ophthalmoparesis, akinetic-rigid features, prominent bulbar dysfunction and fronto-subcortical dementia. There are currently no effective therapies for the treatment of this rapidly degenerating and debilitating disease. Davunetide is a novel neuroprotective peptide that is thought to impact neuronal integrity and cell survival through the stabilization of microtubules. Preclinical activity in models of tauopathy has been translated to clinical studies, demonstrating pharmacologic activity that has supported further development. Davunetide's efficacy and tolerability are being tested in a placebo-controlled study in PSP patients, making it the most advanced drug candidate in this indication. This review examines the disease characteristics of PSP, the rationale for treating PSP with davunetide and assesses some of the challenges of clinical trials in this patient population.

Looking for novel ways to treat the hallmarks of Alzheimer's disease.

Alzheimer's disease (AD) represents an increasing public health issue as demographic changes and generally improved medical care result in a larger aged population. Although significant advances have been made in the diagnosis and treatment of AD, the unmet medical need remains and few treatment options are available. This review focuses on emerging therapies that aim to treat the underlying causes of the disease rather than the symptoms. Such disease-modifying treatments, focused on the two main hallmarks of the disease (plaques and tangles), include new and old targets which have significant potential in the field and are on the cusp of providing new treatment paradigms within the coming years.

NAP: research and development of a peptide derived from activity-dependent neuroprotective protein (ADNP).

Activity-dependent neuroprotective protein (ADNP) is essential for brain formation. Peptide activity scanning identified NAP (NAPVSIPQ) as a small active fragment of ADNP that provides neuroprotection at very low concentrations. In cell culture, NAP has demonstrated protection against toxicity associated with the beta-amyloid peptide, N-methyl-D-aspartate, electrical blockade, the envelope protein of the AIDS virus, dopamine, H2O2, nutrient starvation and zinc overload. NAP has also provided neuroprotection in animal models of apolipoprotein E deficiency, cholinergic toxicity, closed head injury, stroke, middle aged anxiety and cognitive dysfunction. NAP binds to tubulin and facilitates microtubule assembly leading to enhanced cellular survival that is associated with fundamental cytoskeletal elements. A liquid-chromatography, mass spectrometry assay demonstrated that NAP reaches the brain after either intravenous or intranasal administration. In a battery of toxicological tests including repeated dose toxicity in rats and dogs, cardiopulmonary tests in dogs, and functional behavioral assays in rats, no adverse side effects were observed with NAP concentrations that were approximately 500-fold higher than the biologically active dose. A Phase Ia clinical trial in the US assessed the tolerability and pharmacokinetics of intranasal administration of NAP in sequential ascending doses. The results supported the safety and tolerability of a single dose of NAP administered at up to 15 mg intranasally. Furthermore, dosing was recently completed for a second Phase I clinical trial in healthy adults and elderly volunteers with an intravenous formulation of NAP. NAP is poised for further clinical development targeting several indications, including Alzheimer's disease.