Oral GW766944 (Oral CCR3 Antagonist)

GW766994 is a selective, competitive antagonist of the human CC chemokine receptor-3 (CCR3). It is proposed that the inhibition of the CCR3 receptor may provide a treatment for airway inflammation such as in asthma. This will be a double-blind, placebo controlled, parallel group study being conducted to evaluate the effects of GW766994 in subjects with mild-moderate asthma who have high sputum eosinophilia. The primary objective is to compare the effects of GW766994 to placebo on sputum eosinophils.

This will be a multi-centre study. This is a randomized, double-blind, placebo-controlled, parallel-group study, in patients with asthma and eosinophilic bronchitis. Subjects with asthma will be atopic and not on oral prednisone. Inhaled corticosteroids are allowed if on stable dose. All subjects will receive a 5 day course of 30mg daily of oral prednisone after one week stopping study drug.

All subjects will attend screening (Visit 1) at which their eligibility for inclusion will be assessed. Eligible subjects will be randomized to receive either 300 mg of GW766994 twice daily or matching placebo at Day 1 (Visit 2) and will be stratified according to the subject's sputum eosinophil count at Visit 1. Treatment will be 10 days of oral dosing, and subjects will participate in a Day 7 or 8 visit (Visit 3), Day 10 visit (Visit 4 - End of Treatment), followed by a 1 week wash out period (Visit 5 -Follow Up Visit). At Visit 5, all subjects will be given 30 mg oral daily prednisone for 5 days and subjects to return to clinic at a Post Oral Prednisone Visit (Visit 6) at Day 22.

Pharmacodynamic assessments will include both sputum and blood biomarkers and spirometry.

Safety will be assessed by vital sign measurement, electrocardiogram, clinical laboratory tests (hematology, chemistry \& urinalysis), clinical monitoring and adverse event reporting. Pharmacokinetic samples will be collected from each subject according to the sample schedule in the timing and events table.

Study will involved sputum biology (progenitors, cell counts). Study will be conducted in Canada only.

Eligibility Criteria:
Inclusion Criteria:

* Physician diagnosis of asthma (\>12% improvement in FEV1 with a bronchodilator or PC20 methacholine less than 8 mg/ml) documented within the past 2 years.
* Males and females aged ≥18-75 years inclusive.
* A female subject is eligible to participate if she is of:
* Non-childbearing potential defined as pre-menopausal females with a documented tubal ligation or hysterectomy; or postmenopausal defined as 12 months of spontaneous amenorrhea \[in questionable cases a blood sample with simultaneous follicle stimulating hormone (FSH) \> 40 MlU/ml and estradiol \< 40 pg/ml (\<140 pmol/L) is confirmatory\].
* Child-bearing potential and agrees to use one of the contraception methods listed in Section 9.1 for an appropriate period of time (as determined by the product label or investigator) prior to the start of dosing to sufficiently minimize the risk of pregnancy at that point. Female subjects must agree to use contraception until 2 days after the last dose of GW766994.
* Non smoker. Current smokers with a with a pack history of less than 10 years may be enrolled into the study. Subjects who only use chewing tobacco products may be enrolled at the discretion of the Investigator and after consultation with the GSK medical monitor.
* Sputum eosinophils \>4.9%.
* AST, ALT, alkaline phosphatase and bilirubin \>1.5xULN (isolated bilirubin \>1.5xULN is acceptable if bilirubin is fractionated and direct bilirubin \<35%).
* QTcB or QTcF \< 450 msec assessed within 6 months of the screening visit.
* To be eligible, female patients must have a negative urine pregnancy test.
* Capable of giving written informed consent, which includes compliance with the requirements and restrictions listed in the consent form.
* The subject is able to understand and comply with protocol requirements, instructions and protocol- stated restrictions.

Exclusion Criteria:

* Any clinically relevant abnormality identified on the screening medical assessment, laboratory examination, or ECG.
* Current smokers.
* Subjects unable to produce a technically acceptable sputum sample.
* Sputum TCC \>25 million cells/g.
* Clinically significant hepatic impairment or current or chronic history of liver disease or known hepatic or biliary abnormalities (with the exception of Gilbert's syndrome or asymptomatic gallstones)
* Positive HIV, Hepatitis B surface antigen or Hepatitis C antibody within 3 months of screening.
* The subject regularly drinks more than 28 units of alcohol in a week, if male or 21 units per week, if female. One unit of alcohol is defined as a medium (125ml) glass of wine, half a pint (250ml) of beer, or one measure (25ml) of spirits.
* Pregnant and lactating women.
* Asthma considered unstable within 2 months prioir to screening.
* Respiratory Infection: Culture-documented or suspected bacterial or viral infection of the upper or lower respiratory tract, sinus or middle ear that is not resolved within the 4 weeks before screening and led to a change in asthma management, or in the opinion of the Investigator is expected to affect the subjects asthma status or the subjects ability to participate in the study.
* Baseline post-bronchodilator FEV1 \<50% predicted (spirometry to be done at screening visit).
* Regular oral prednisone use.
* Subjects who have received therapy with monoclonal antibodies within the proceeding 3 months prior to screening visit.
* Co-morbidities that, in the investigator's opinion may interfere with study including systemic inflammatory conditions such as rheumatoid arthritis.
* Donation of blood in excess of 500 mL within a 56-day period prior to dosing
* Participation in a trial with any drug within 30 days or 5 half-lives (whichever is longer), or participation in a trial with a new chemical entity within 2 months prior to first dose of current study medication, unless in the opinion of the Investigator and sponsor the medication will not interfere with the study procedures or compromise subject safety.
* The subject has a positive pre-study drug/alcohol screen. A minimum list of drugs that will be screened but not limited to amphetamines, barbiturates, cocaine, opiates, and cannabinoids.

Subjects who use benzodiazepines or other anxiolytic on a regular basis can be included at the discretion of the investigator and in consultation with the GSK medical monitor.

* Cytochrome P450 3A4 inhibitors including but not limited to antiretrovirals (protease inhibitors) (e.g.indinavir, nelfinavir, ritonavir, saquinavir); imidazole and triazole anti-fungals (e.g.

ketaconazole, itraconazole); macrolide antibiotics (e.g. clarithromycin, erytrhomycin and; telithromycin); calcium channel blockers (diltiazem and verapamil) and nefazodone, 6 weeks before.

* Consumption of seville oranges, grapefruit or grapefruit juice and/or pummelos, exotic citrus fruits, grapefruit hybrids or fruit juices from 7 days prior to the first dose of study medication.
* Unwillingness or inability to follow the procedures outlined in the protocol.