Study of Mometasone Furoate/Formoterol Combination and Fluticasone/Salmeterol in Persistent Asthmatics Previously Treated With Inhaled Glucocorticosteroids (P04139)

Inclusion Criteria: * Subjects of either sex and any race, at least 12 years of age, with a diagnosis of asthma of at least 12 months. * Use of medium or high daily dose of ICS (alone or in combination with long-acting beta-agonist \[LABA\]) for at least 12 weeks prior to Screening and have been on a stable regimen for at least 2 weeks prior to Screening. * Medium daily doses of ICS: * \> 500 to 1000 mcg beclomethasone chlorofluorocarbon (CFC) * \> 250 to 500 mcg beclomethasone hydrofluoroalkane (HFA) * \> 600 to 1000 mcg budesonide dry powder inhaler (DPI) * \> 1000 to 2000 mcg flunisolide * \> 250 to 500 mcg fluticasone * 400 mcg MF * \> 1000 to 2000 mcg triamcinolone acetonide * High daily doses of ICS: * \> 1000 mcg beclomethasone CFC * \> 500 mcg beclomethasone HFA * \> 1000 mcg budesonide DPI * \> 2000 mcg flunisolide * \> 500 mcg fluticasone * \> 400 mcg MF * \> 2000 mcg triamcinolone acetonide * If there is no inherent harm in changing the subject's current asthma therapy, the subject must discontinue prescribed ICS or ICS/LABA combination at Baseline. * Must show evidence of reversibility within the last 12 months or during the Screening Period. Historical reversibility defined as an increase in absolute forced expiratory volume in 1 second (FEV1) of \>= 12% and \>= 200 mL will qualify if performed within 12 months of Screening. If no historical reversibility, subject must demonstrate an absolute FEV1 of \>= 12% and \>= 200 mL within 10 to 15 minutes after four puffs of salbutamol at Visit 1 or anytime prior to Baseline. * At Screening and Baseline, FEV1 must be \>= 50% predicted, when restricted medications are withheld for the appropriate intervals. * Complete blood count, blood chemistries, urinalysis, and electrocardiogram (ECG) conducted at Screening must be within normal limits or clinically acceptable to the investigator/sponsor. A chest x-ray performed at Screening or within 12 months prior must be clinically acceptable. * A female of childbearing potential must be using a medically acceptable, adequate form of birth control: * prescribed hormonal contraceptives; * medically prescribed intrauterine device (IUD); * medically prescribed transdermal contraceptive; * condom in combination with spermicide; * monogamous relationship with a male partner who has had a vasectomy. Birth control must have started at least 3 months prior to Screening. Subject must agree to continue its use for the duration of the study. A subject of childbearing potential who is not currently sexually active must agree to use a medically acceptable method should she become sexually active during the study. Women who have been surgically sterilized or are at least 1 year postmenopausal are not considered to be of childbearing potential. A subject of childbearing potential must have a negative serum pregnancy test at Screening. Key Exclusion Criteria: * A change (increase or decrease) in absolute FEV1 of \> 20% at any time from the Screening Visit up to, and including, the Baseline Visit. * A subject who requires the use of \> 12 inhalations per day of short-acting beta-agonist (SABA) MDI or \> 2 nebulized treatments per day of 2.5 mg salbutamol, on any 2 consecutive days from the Screening Visit up to, and including, the Baseline Visit. * A subject who experiences a clinical asthma exacerbation (defined as a deterioration of asthma that results in emergency treatment, hospitalization due to asthma, or treatment with additional, excluded asthma medication \[other than SABA\]) at any time from the Screening Visit up to, and including, the Baseline Visit. * A subject who has ever required ventilator support for respiratory failure secondary to asthma. * A subject who is a smoker or ex-smoker and has smoked within the previous year or has had a cumulative smoking history \> 10 pack-years.