Foundation-Directed Therapeutic Development in Huntington’s Disease

Huntington’s disease (HD) is an autosomal dominant neurodegenerative disease that devastates patients and their families. It is caused by expansion of the CAG repeat in the huntingtin gene (<i>HTT</i>) and characterized pathologically by the loss of pyramidal neurons in several cortical areas, striatal medium spiny neurons, and hypothalamic neurons. Clinically, a distinguishing feature of the disease is uncontrolled involuntary movements (chorea) accompanied by progressive cognitive and psychiatric impairment. Currently there are no effective disease-modifying treatments for HD, although antidepressant and antipsychotic medications are typically utilized to manage HD symptoms, in addition to the only approved drug for the treatment of chorea in HD, tetrabenazine (TBZ). CHDI is a not-for-profit organization focused solely on HD. Herein we describe our foundation-directed therapeutic development efforts highlighting our collaborations and internal programs that are in various stages of development

Inter- and Intramolecular Annulation Strategies to a Cyclopentanone Building Block Containing an All-Carbon Quaternary Stereogenic Center

Synthesis of (<i>S</i>)<i>-</i>2-methyl-3-fluorophenyl cyclopentanone methyl ester (1<i>S</i>)-<b>1</b> has been achieved by both inter- and intramolecular alkylation reactions on multigram scale, using chiral pool reagents. The intramolecular variant is a novel example of a chiral <i>bis</i>-electrophile reacting with a carbon nucleophile to form an enantiomerically pure all-carbon quaternary center

Influence of D159797 on OR trial performance.

<p>Effects of D159797 on easy (open bars) versus difficult tasks (black bars). Dose-dependent improvement in (A) mean percent correct first reach on difficult task performance. Individual animal performance plot in easy trials (B) and in difficult trials (C). (D–E) Dose-dependent reduction in the total number of reaches (D) and barrier reaches (E) on difficult tasks. (A, D, E) Values are listed as mean ± SEM (n = 8 for vehicle and low dose, and n = 7 for mid and high dose group). Asterisks denote significant differences from vehicle treatment (* p<0.05, **p<0.01 and ***p<0.001) following repeat measures one-way ANOVA and Dunnett's post-hoc analysis (n = 7, due to non-completer 7A5D).</p

Object retrieval task schematic and baseline characterization.

<p>(A) Order of object retrieval task sessions for easy and difficult trials. Drawings illustrate the position of the reward in the boxes. (*) Left position will become right and right position will become left and so on in weekly rotation throughout the study. (#) The <b>bold</b> side of the cube represents the open side of the cube. (**) Trial 17 was for reward purposes and was not included in the data analysis; (B) Box (line indicates median, * indicates mean, box represents upper and lower 25 percentiles) and whisker (maximum to minimum) plots of all animal performance during the 4 training sessions and to vehicle administration during the testing phase on both easy (grey) and difficult (black) trials. Dashed lines indicate targeted performance – performance in easy trials >50% correct first reach, and performance in difficult trials <40% correct first reach. (C) Same data as in (B) but with high performer animal 3939 excluded. Criteria are largely met by exclusion of this animal. The outlier value during the rolipram vehicle trial is due to animal 7A5D.</p

Summary of plasma pharmacokinetic parameters of D159797 following single intravenous administration at 1.0/kg, and on day 1 and day 7 after repeated daily oral administration at 5.0 mg/kg.

<p>Data presented as mean ± SD of 3 animals.</p

Influence of D159687 on OR trial performance.

<p>Effects of D159687 on easy (open bars) versus difficult task (black bars). Dose-dependent improvement in (A) mean percent correct first reach on difficult task performance, with modest improvement on easy trial performance. Individual animal performance plot in easy trials (B) and in difficult trials (C). (D–E) Dose-dependent reduction in the total number of reaches (D) and barrier reaches (E) on difficult taks. (A, D, E) Values are listed as mean ± SEM (n = 8 for vehicle, low and mid-dose groups, n = 7 for high dose group). Asterisks denote significant differences from vehicle treatment (* p<0.05, **p<0.01 and ***p<0.001) following repeat measures one-way ANOVA and Dunnett's post-hoc analysis (n = 7, due to non-completer 7A5D).</p

Pharmacokinetic analysis of PDE4D NAMs in female Cynomolgous monkeys.

<p>(A–B) Plasma exposure of D159687 (A), or D159797 (B) in female Cynomolgus monkey plasma following a single intravenous administration at 1.0 mg/kg, and on day 1 and day 7 after repeated daily oral administration at 5.0 mg/kg.</p

Summary of plasma pharmacokinetic parameters of D159687 following single intravenous administration at 1.0/kg, and on day 1 and day 7 after repeated daily oral administration at 5.0 mg/kg.

<p>Data presented as mean ± SD of 3 animals.</p><p>*Calculated from n = 2, as due to patency issues in catheter of one animal following IV dosing, one animal was replaced for po dosing, thus, it was not a cross over design.</p

Quantifying autophagy using novel LC3B and p62 TR-FRET assays

<div><p>Autophagy is a cellular mechanism that can generate energy for cells or clear misfolded or aggregated proteins, and upregulating this process has been proposed as a therapeutic approach for neurodegenerative diseases. Here we describe a novel set of LC3B-II and p62 time-resolved fluorescence resonance energy transfer (TR-FRET) assays that can detect changes in autophagy in the absence of exogenous labels. Lipidated LC3 is a marker of autophagosomes, while p62 is a substrate of autophagy. These assays can be employed in high-throughput screens to identify novel autophagy upregulators, and can measure autophagy changes in cultured cells or tissues after genetic or pharmacological interventions. We also demonstrate that different cells exhibit varying autophagic responses to pharmacological interventions. Overall, it is clear that a battery of readouts is required to make conclusions about changes in autophagy.</p></div

Table_4_Noninvasive Relative Quantification of [11C]ABP688 PET Imaging in Mice Versus an Input Function Measured Over an Arteriovenous Shunt.DOCX

<p>Impairment of the metabotropic glutamate receptor 5 (mGluR5) has been implicated with various neurologic disorders. Although mGluR5 density can be quantified with the PET radiotracer [¹¹C]ABP688, the methods for reproducible quantification of [¹¹C]ABP688 PET imaging in mice have not been thoroughly investigated yet. Thus, this study aimed to assess and validate cerebellum as reference region for simplified reference tissue model (SRTM), investigate the feasibility of a noninvasive cardiac image-derived input function (IDIF) for relative quantification, to validate the use of a PET template instead of an MRI template for spatial normalization, and to determine the reproducibility and within-subject variability of [¹¹C]ABP688 PET imaging in mice. Blocking with the mGluR5 antagonist MPEP resulted in a reduction of [¹¹C]ABP688 binding of 41% in striatum (p < 0.0001), while no significant effect could be found in cerebellum (−4.8%, p > 0.99) indicating cerebellum as suitable reference region for mice. DVR-1 calculated using a noninvasive IDIF and an arteriovenous input function correlated significantly when considering the cerebellum as the reference region (striatum: DVR-1, r = 0.978, p < 0.0001). Additionally, strong correlations between binding potential calculated from SRTM (BP_ND) with DVR-1 based on IDIF (striatum: r = 0.980, p < 0.0001) and AV shunt (striatum: r = 0.987, p < 0.0001). BP_ND displayed higher discrimination power than V_T values in determining differences between wild-types and heterozygous Q175 mice, an animal model of Huntington's disease. Furthermore, we showed high agreement between PET- and MRI-based spatial normalization approaches (striatum: r = 0.989, p < 0.0001). Finally, both spatial normalization approaches did not reveal any significant bias between test-retest scans, with a relative difference below 5%. This study indicates that noninvasive quantification of [¹¹C]ABP688 PET imaging is reproducible and cerebellum can be used as reference region in mice.</p