PF-02545920

The UHDRS was a clinical rating scale which has been developed by the Huntington Disease Study Group (HSG) to provide a uniform assessment of the clinical features and course of Huntington's Disease (HD). The components of the full UHDRS assess motor function, cognition, behavior and functional abilities. The total motor score (TMS) assessed motor features of HD with standardized ratings of oculomotor function, dysarthria, chorea, dystonia, gait, and postural stability. Some items (such as chorea and dystonia) required grading each extremity (face, bucco-oral-lingual, and trunk) separately. Eye movements require both horizontal and vertical grades. The total motor impairment scores was the sum of all the individual 31 motor sub-items (each rated from 0 to 4), with higher scores indicating more severe motor impairment than lower scores. The range of TMS is 0-124.

An AE was any untoward medical occurrence without regard to causality in a participant who received study drug. An SAE was an AE resulting in any of the following outcomes or deemed significant for any other reason: death; initial or prolonged inpatient hospitalization; life-threatening experience (immediate risk of dying); persistent or significant disability/incapacity; congenital anomaly. Treatment-emergent are events between first dose of treatment and up to the follow-up period that were absent before treatment or that worsened relative to pretreatment state. AEs included both SAEs and non-serious AEs.

The following laboratory parameters were analyzed: hematology (hemoglobin, hematocrit, red blood cell \[RBC\] count, platelet count, white blood cell \[WBC\] count, total neutrophils, eosinophils, monocytes, basophils, lymphocytes); blood chemistry (blood urea nitrogen \[BUN\], creatinine, glucose, calcium, sodium, potassium, chloride, total bicarbonate, aspartate aminotransferase \[AST\], alanine aminotransferase \[ALT\], total and direct bilirubin, alkaline phosphatase, uric acid, albumin, and total protein; urinalysis (pH, glucose, protein/albumin, hemoglobin/blood, ketones/acetone, nitrites, leukocyte esterase, microscopy \[if urine dipstick was positive for blood, protein, nitrites or leukocyte esterase\]); others (urine/serum pregnancy test, glycosylated hemoglobin \[HbA1c, if diabetic\]).

Vital signs assessment included pulse rate and blood pressure. Criteria for vital sign values meeting potential clinical concern included: supine/sitting pulse rate less than (\<)40 or greater than (\>)120 beats per minute (bpm), standing pulse rate \<40 or \>140 bpm; systolic blood pressure (SBP) of greater than or equal to (\>=)30 millimeters of mercury (mmHg) change from baseline or SBP \<90 mmHg, diastolic blood pressure (DBP) \>=20 mmHg change from baseline or DBP \<50 mmHg.

ECG parameters included PR interval, QRS complex, and corrected QT interval using Fridericia's formula (QTcF). Criteria for ECG changes meeting potential clinical concern included: PR interval ≥200 milliseconds (msec) or ≥25% increase when baseline is \>100 msec; QRS interval ≥50% increase from baseline when baseline is less than or equal to (\<=)200 msec; and QTcF ≥450 msec or ≥30 msec increase from baseline.

Weight assessment was performed by a study physician or a trained study nurse and was included in the physical examination.

Absolute neutrophil count (ANC) and WBC were monitored for safety. Participants with WBC \<3000 but \>=2000 cells/mm\^3 or ANC \<1500 but \>=1000 cells/mm\^3 were to have study treatment suspended. Participants with WBC \<2000 or ANC \<1000 cells/mm\^3 were to be discontinued from study participation.

The UHDRS is a clinical rating scale to provide a uniform assessment of the clinical features and course of Huntington Disease. The Total Motor Score (TMS) is 1 of the 6 components of UHDRS, includes 31 items, and ranges from a scale of 0 to 124 (higher scores indicate more severe disease).

C-SSRS is a participant rated questionnaire to assess suicidal ideation, suicidal behavior, actual attempts (yes or no responses), and intensity of ideation (rated 1=low severity to 5=high severity). Yes/No responses are mapped to Columbia Classification Algorithm of Suicide Assessment (C-CASA) categories: completed suicide, suicide attempt, preparatory acts towards imminent suicidal behavior, suicidal ideation, and self-injurious behavior, or no suicidal intent. A participant could have a yes or no response in more than 1 category.

C-SSRS is a participant rated questionnaire to assess suicidal ideation, suicidal behavior, actual attempts (yes or no responses), and intensity of ideation (rated 1=low severity to 5=high severity). Yes/No responses are mapped to Columbia Classification Algorithm of Suicide Assessment (C-CASA) categories: completed suicide, suicide attempt, preparatory acts toward imminent suicidal behavior, suicidal ideation, and self-injurious behavior, or no suicidal intent. A participant could have a yes or no response in more than 1 category.

C-SSRS is a participant rated questionnaire to assess suicidal ideation, suicidal behavior, actual attempts (yes or no responses), and intensity of ideation (rated 1=low severity to 5=high severity). Yes/No responses are mapped to Columbia Classification Algorithm of Suicide Assessment (C-CASA) categories: completed suicide, suicide attempt, preparatory acts toward imminent suicidal behavior, suicidal ideation, and self-injurious behavior, or no suicidal intent. A participant could have a yes or no response in more than 1 category.

PANSS assesses the positive symptoms, negative symptoms, and general psychopathology specifically associated with schizophrenia. The scale consists of 30 items. Each item is rated on a scale from 1 (symptom not present) to 7 (symptoms extremely severe). The sum of the 30 items is defined as the PANSS total score and ranges from 30 to 210; higher score indicates greater severity.

Participants were assessed for presence of symptoms for any one of the following: dystonia, oromandibular dystonia, and oculogyric crisis.

Using Positron Emission Tomography and a radiotracer (MNI-659) for PF-02545920, the central PDE10A enzyme occupancy values will be measured in the striatum at different single oral doses of PF-02545920.

ESRS-A is a clinician rated scale consisting of 24 items to assess severity of extrapyramidal symptoms for following parameters: parkinsonism (10 items), dystonia (6 items), dyskinesia (6 items) and akathisia (2 items). Each item was scored on a 6-point scale (0=absent, 1=minimal, 2=mild, 3=moderate, 4=severe, 5=extreme). Additionally, 4 Clinical Global Impression of Severity (CGI-S) items were assessed on a 7-point scale (1=normal, not ill at all; 2=borderline mentally ill; 3=mildly ill; 4=moderately ill; 5=markedly ill; 6=severely ill; 7=extremely ill): CGI-S parkinsonism; CGI-S dystonia; CGI-S dyskinesia; CGI-S akathisia.

ESRS-A is a clinician rated scale consisting of 24 items to assess severity of extrapyramidal symptoms for following parameters: parkinsonism (10 items), dystonia (6 items), dyskinesia (6 items) and akathisia (2 items). Each item is scored on a 6-point Likert scale (0=absent, 1=minimal, 2=mild, 3=moderate, 4=severe, 5=extreme). Additionally, 4 CGI-S items were assessed on a 7-point scale (1=normal, not ill at all; 2=borderline mentally ill; 3=mildly ill; 4=moderately ill; 5=markedly ill; 6=severely ill; 7=extremely ill): CGI-S parkinsonism; CGI-S dystonia; CGI-S dyskinesia; CGI-S akathisia.

Data relevant to the assessment of suicidality was mapped to the Columbia-Classification Algorithm of Suicide Assessment (C-CASA) event codes. C-SSRS assessed whether participant experienced following: completed suicide (Event code 1), suicide attempt (Event code 2) (Response of "Yes" on "actual attempt"), preparatory acts toward imminent suicidal behavior (Event code 3) ("Yes" on "aborted attempt", "interrupted attempt", "preparatory acts or behavior"), suicidal ideation (Event code 4) ("Yes" on "wish to be dead", "non-specific active suicidal thoughts", "active suicidal ideation with methods without intent to act/some intent to act without specific plan or with specific plan and intent), self-injurious behavior, no suicidal intent (Event code 7) ("Yes" on "Has participant engaged in non-suicidal self-injurious behavior"). Number of participants with "Yes" response for above mentioned categories were assessed.

Data relevant to the assessment of suicidality was mapped to the C-CASA event codes. C-SSRS assessed whether participant experienced following: completed suicide (Event code 1), Suicide attempt (Event code 2) (Response of "Yes" on "actual attempt"), preparatory acts toward imminent suicidal behavior (Event code 3) ("Yes" on "aborted attempt", "interrupted attempt", "preparatory acts or behavior"), suicidal ideation (Event code 4) ("Yes" on "wish to be dead", "non-specific active suicidal thoughts", "active suicidal ideation with methods without intent to act/some intent to act without specific plan or with specific plan and intent), self-injurious behavior, no suicidal intent (Event code 7) ("Yes" on "Has participant engaged in non-suicidal self-injurious behavior"). Number of participants with "Yes" response for above mentioned categories were assessed.

Data relevant to the assessment of suicidality was mapped to the C-CASA event codes. C-SSRS assessed whether participant experienced following: completed suicide (Event code 1), Suicide attempt (Event code 2) (Response of "Yes" on "actual attempt"), preparatory acts toward imminent suicidal behavior (Event code 3) ("Yes" on "aborted attempt", "interrupted attempt", "preparatory acts or behavior"), suicidal ideation (Event code 4) ("Yes" on "wish to be dead", "non-specific active suicidal thoughts", "active suicidal ideation with methods without intent to act/some intent to act without specific plan or with specific plan and intent), self-injurious behavior, no suicidal intent (Event code 7) ("Yes" on "Has participant engaged in non-suicidal self-injurious behavior"). Number of participants with "Yes" response for above mentioned categories were assessed.

Data relevant to the assessment of suicidality was mapped to the C-CASA event codes. C-SSRS assessed whether participant experienced following: Completed suicide (Event code 1), Suicide attempt (Event code 2) (Response of "Yes" on "actual attempt"), preparatory acts toward imminent suicidal behavior (Event code 3) ("Yes" on "aborted attempt", "interrupted attempt", "preparatory acts or behavior"), suicidal ideation (Event code 4) ("Yes" on "wish to be dead", "non-specific active suicidal thoughts", "active suicidal ideation with methods without intent to act/some intent to act without specific plan or with specific plan and intent), self-injurious behavior, no suicidal intent (Event code 7) ("Yes" on "Has participant engaged in non-suicidal self-injurious behavior"). Number of participants with "Yes" response for above mentioned categories were assessed.

Data relevant to the assessment of suicidality was mapped to the C-CASA event codes. C-SSRS assessed whether participant experienced following: Completed suicide (Event code 1), Suicide attempt (Event code 2) (Response of "Yes" on "actual attempt"), preparatory acts toward imminent suicidal behavior (Event code 3) ("Yes" on "aborted attempt", "interrupted attempt", "preparatory acts or behavior"), suicidal ideation (Event code 4) ("Yes" on "wish to be dead", "non-specific active suicidal thoughts", "active suicidal ideation with methods without intent to act/some intent to act without specific plan or with specific plan and intent), self-injurious behavior, no suicidal intent (Event code 7) ("Yes" on "Has participant engaged in non-suicidal self-injurious behavior"). Number of participants with "Yes" response for above mentioned categories were assessed.

Data relevant to the assessment of suicidality was mapped to the C-CASA event codes. C-SSRS assessed whether participant experienced following: Completed suicide (Event code 1), Suicide attempt (Event code 2) (Response of "Yes" on "actual attempt"), preparatory acts toward imminent suicidal behavior (Event code 3) ("Yes" on "aborted attempt", "interrupted attempt", "preparatory acts or behavior"), suicidal ideation (Event code 4) ("Yes" on "wish to be dead", "non-specific active suicidal thoughts", "active suicidal ideation with methods without intent to act/some intent to act without specific plan or with specific plan and intent), self-injurious behavior, no suicidal intent (Event code 7) ("Yes" on "Has participant engaged in non-suicidal self-injurious behavior"). Number of participants with "Yes" response for above mentioned categories were assessed.

A complete physical examination included head, ears, eyes, nose, mouth, skin, heart and lung examinations, lymph nodes, gastrointestinal, musculoskeletal, and neurological systems was performed at Screening. The limited or abbreviated physical examination was focused on general appearance, the respiratory and cardiovascular systems, as well as towards assessment of subject reported symptoms and performed at other time points than Screening.

A complete physical examination included head, ears, eyes, nose, mouth, skin, heart and lung examinations, lymph nodes, gastrointestinal, musculoskeletal, and neurological systems was performed at Screening. The limited or abbreviated physical examination was focused on general appearance, the respiratory and cardiovascular systems, as well as towards assessment of subject reported symptoms and performed at other time points than Screening.

The neurological examination included observation for cerebellar (intention) tremor and for non-cerebellar tremors (eg, resting or positional), finger-nose, heel-shin, Romberg, tandem walking, positional and gaze-evoked nystagmus.

The neurological examination included observation for cerebellar (intention) tremor and for non-cerebellar tremors (eg, resting or positional), finger-nose, heel-shin, Romberg, tandem walking, positional and gaze-evoked nystagmus.

An AE was defined as any untoward medical occurrence in a participant who received study drug without regard to possibility of causal relationship. Treatment-emergent were events between first dose of study drug and up to last subject visit that were absent before treatment or that worsened relative to pretreatment state.

An AE was defined as any untoward medical occurrence in a participant who received study drug without regard to possibility of causal relationship. Treatment-emergent were events between first dose of study drug and up to last subject visit that were absent before treatment or that worsened relative to pretreatment state.

The total number of participants with laboratory test abnormalities without regard to baseline abnormality was assessed.

The total number of participants with laboratory test abnormalities without regard to baseline abnormality was assessed.

Vital signs included blood pressure (BP; supine and standing) and pulse rate. Vital signs criteria of potential clinical concern were 1), BP: systolic \>=30 millimeters of mercury (mm Hg) change from baseline in same posture, systolic \<90 mm Hg; diastolic \>=20 mm Hg change from baseline in same posture, diastolic \<50 mm Hg; 2), pulse rate (supine/sitting): \<40 or greater than (\>) 120 beats per minute (bpm); Standing: \<40 or \>140 bpm.

Vital signs included BP (supine and standing) and pulse rate. Vital signs criteria of potential clinical concern were 1), BP: systolic \>=30 mm Hg change from baseline in same posture, systolic \<90 mm Hg; diastolic \>=20 mm Hg change from baseline in same posture, diastolic \<50 mm Hg; 2), pulse rate (supine/sitting): \<40 or \>120 bpm; Standing: \<40 or \>140 bpm.

12-lead ECG (triplicate) was performed on Day 0 and 12-lead ECG (singlet) was performed at other time points as specified in timeframe. ECG criteria of potential clinical concern were 1), PR interval: \>=300 milliseconds (msec); \>=25% increase when baseline was greater than (\>) 200 msec; or increase \>=50% when baseline was less than or equal to (\<=) 200 msec; 2), QRS interval: \>=140 msec; \>=50% increase from baseline; 3), corrected QT interval (QTc interval): \>=500 msec, QTc interval using Fridericia's formula (QTcF interval): absolute value \>=450 - \<480 msec(borderline), \>=480 msec (prolonged); absolute change 30 - \<60 (borderline), \>=60 msec (prolonged).

12-lead ECG (triplicate)was performed on Day 0 and 12-lead ECG (singlet) was performed at other time points as specified in timeframe. ECG criteria of potential clinical concern were 1), PR interval: \>=300 msec; \>=25% increase when baseline \>200 msec; or increase \>=50% when baseline \<=200 msec; 2), QRS interval: \>=140 msec; \>=50% increase from baseline; 3), QTc interval: \>=500 msec, QTcF interval: absolute value \>=450 - \<480 msec (borderline), \>=480 msec (prolonged); absolute change 30 - \<60 (borderline), \>=60 msec (prolonged).