The Effects of Omalizumab (Anti-IgE) on the Late-phase Response to Nasal Allergen Challenge

This is a randomized, placebo-controlled, double-blind, parallel group design study that
includes 3.5 months of treatment with omalizumab or placebo and a 3 month follow-up. All
subjects will be cat allergic.

Twenty four subjects (1:1 randomization) will undergo a cat allergen nasal challenge prior
to treatment and another challenge after 2 months of treatment or when their blood basophils
become hyporesponsive to cat allergen in vitro. A second group of 10 subjects (1:1
active:placebo), will not undergo nasal challenges. This group will participate in an
ancillary study in which the effects of omalizumab on gene expression profiles in peripheral
blood cells will be studied.

Inclusion:

1. Male or female, ages 18-50

2. Females must be surgically sterile or postmenopausal or using a specified acceptable
form of birth control throughout the duration of the study. Females in certain
categories (not sexually active, vasectomized partner) will be admitted at the
discretion of the investigator on a case-by-case basis.

3. Females must have a negative urine pregnancy test at Visit A and other visits
specified in this protocol.

4. Clinical history of perennial allergic rhinitis for at least two years, with or
without seasonal allergic rhinitis, and with or without mild persistent asthma as
define by the 2007 NAEPP guidelines.

5. Allergic cat sensitization defined by a positive puncture skin test (mean wheal
diameter 3 mm or more greater than diluent control), and a positive CAP-RAST to cat >
0.35 kU/L.

6. Positive intranasal cat allergen challenge defined by the induction of a total of ≥ 5
sneezes at screening(criterion not applicable in the ancillary study).

7. Baseline in vitro histamine release of peripheral blood basophils to cat allergen
≥7%.

8. Peripheral blood basophils > two million per 100 ml of blood (criterion only
applicable in the ancillary study)

Exclusion Criteria:

1. Asthma with baseline FEV1 < 80% predicted, and/or moderate to severe asthma
classification per the 2007 NAEPP guidelines.

2. Individuals with total serum IgE levels less than 30 IU/mL or greater than 700 IU/mL
at the time of enrollment.

3. Individuals with reduced hematocrit (< 32%), WBC count (2400/microliter), platelet
count (< 75000/microliter), and increased creatinine (> 141.4 micromolar/L), or AST
(> 100 IU/L).

4. Individuals with body weight less than 30 kg or greater than 150 kg.

5. Pregnant females or females with plans to become pregnant or breastfeed during the
duration of the study.

6. Individuals with perforated nasal septum, structural nasal defects, large nasal
polyps causing obstruction, evidence of acute or chronic sinusitis.

7. History of malignancy, anaphylaxis or bleeding disorder.

8. Mental illness or history of drug or alcohol abuse that, in the opinion of the
investigator, would interfere with the participant's ability to comply with study
requirements.

9. Inability or unwillingness of a participant to give written informed consent or
comply with study protocol.

10. Use of any investigational drugs within 8 weeks of participation.

11. Contraindications to omalizumab including patients with a previous hypersensitivity
to omalizumab.

12. Recent recipient of any licensed or investigational live attenuated vaccine(s) within
two months of study initiation such as flu mist.

13. Any prior use of omalizumab.

14. Frequent episodes of acute sinusitis (>2 documented episodes per year) or active
sinusitis within 2 weeks prior to enrollment

15. Use of aeroallergen immunotherapy within 5 years prior to enrollment

16. Current or within 4 weeks prior to enrollment use of nasal steroids, nasal cromolyn
or oral steroids

17. Past or current medical problems or findings from physical examination or laboratory
testing that are not listed above, which, in the opinion of the investigator, may
pose additional risks from participation in the study, may interfere with the
participant's ability to comply with study requirements or may compromise the quality