Anti-TSLP (AMG 157) Plus Antigen-Specific Immunotherapy for Induction of Tolerance in Individuals With Cat Allergy

This study will implement the concept referred to as "allergen-plus," which aims to enhance
the disease-modifying mechanisms of allergen-specific immunotherapy by combining it with
other anti-inflammatory or immune-modulating agents. Thymic stromal lymphopoietin (TSLP) is a
cytokine which appears to be instrumental in both initiating and maintaining allergic
sensitivity to antigens, and Immune Tolerance Network (ITN) investigators hypothesize that
blocking TSLP during the administration of cat immunotherapy will induce durable immune
changes that lead to tolerance.

CATNIP will be conducted at multiple sites in the US and enroll cat‐allergic adults who will
be randomized to four possible treatment groups: immunotherapy plus MEDI9929/AMG 157,
immunotherapy plus placebo, placebo plus MEDI9929/AMG 157, or two corresponding placebos.
This study is specifically enrolling cat allergic individuals who do not live with cats in
order to limit exposure to the allergen outside of the study. Treatment will be given for
about one year, followed by one year off therapy.

Inclusion Criteria:

- History of moderate-severe allergic rhinitis caused by cat exposure for at least 2 yrs

- Skin prick test wheal >/=5 mm to standardized cat extract

- Immunoglobulin E (IgE) >/=0.7 kU/L (class 2) to cat extract

- Screening nasal allergen challenge in which:

*TNSS is
- TNSS increase is the 0 concentration (vehicle control only) dose,

- TNSS is >/=8 after the highest dose, and

- Between the first non-zero dose and 10 minutes after the highest dose,either:

- >/=3 sneezes are counted or

- >20% drop in PNIF is recorded

- Body mass index (BMI) between 1 and 32 kg/m^2, inclusive at screening

- Clinically acceptable physical examination and electrocardiogram (ECG) results
(12-lead reporting RR, PR, QRS, QT and QTcF) prior to Day 0 based on the opinion of
the investigator

- Adequate renal function (defined by creatinine clearance >80 mL/min using the
Cockcroft Gault equation)

- For women of childbearing age, a willingness to use a highly effective form of
contraception for five months after last dose of study medication. Highly effective
methods of birth control include abstinence, vasectomy by the male partner, or a
condom with spermicide in combination with either hormonal birth control, IUD or
barrier methods used by the woman.

- For men with female partners of childbearing potential, agreement not to donate sperm
and to inform their female partner of their participation in this clinical study and
use highly effective methods of birth control for five months after last dose of study
medication. Highly effective methods of birth control include abstinence, vasectomy,
or a condom with spermicide in combination with either hormonal birth control,
Intrauterine device (IUD) or barrier methods used by the woman.

- The ability to give informed consent and comply with study procedures

Exclusion Criteria:

- Prebronchodilator Forced Expiratory Volume at one second (FEV1) less than 0% of
predicted value at screening visit

- History of moderate or higher Allergic Rhinitis and its Impact on Asthma (ARIA)
severity classification for allergic rhinitis in the last year due to allergens other
than cat

- History of asthma meeting the National Asthma Education and Prevention Program (NAEPP)
Expert Panel Report 3 (EPR3) classification of mild-persistent or worse in the past
year, other than with cat exposure, requiring regular inhaled corticosteroids for >4
weeks per year

- History of serious chronic medical conditions which might interfere with treatment or
assessments

- History of emergency visit or hospital admission for asthma in the previous 12 months

- History of chronic obstructive pulmonary disease (COPD)

- History of significant recurrent acute sinusitis, defined as 2 episodes/yr for the
last 2 years, all of which required antibiotic treatment

- History of chronic sinusitis, defined as a sinus symptoms lasting >12 weeks that
includes >/=2 major factors or 1 major factor and 2 minor factors. Major factors are
defined as facial pain or pressure, nasal obstruction or blockage, purulent or
discolored postnasal discharge, purulence in nasal cavity, or impaired or loss of
smell. Minor factors are defined as headache, fever, halitosis, fatigue, dental pain,
cough, and ear pain, pressure, or fullness.

- History of systemic disease affecting the immune system such as autoimmune diseases,
immune complex disease, or immunodeficiency, where, in the opinion of the study
physician, participation in the trial would pose a risk or significant effect on the
immune system

- Diabetes (Type I or II)

- Evidence of any active or suspected bacterial, viral, fungal or parasitic infection(s)
within 30 days prior to randomization

- High risk of parasitic disease as judged by the investigator

- Positive QuantiFERON(R) tuberculin test UNLESS the potential subject has been treated
with appropriate chemoprophylaxis

- Exposure to an individual with active tuberculosis within six months from
randomization

- Subjects tested positive for HIV antibody, Hep B surface antigen, or Hep C antibody

- At randomization, current symptoms of, or treatment for, upper respiratory tract
infection, acute sinusitis, acute otitis media, or other relevant infectious process;
serous otitis media is not an exclusion criterion. Participants may be re-evaluated
for eligibility after symptoms resolve.

- History of malignancy of any type, including basal cell and squamous cell cancers of
the skin, within 5 years of enrollment

- Tobacco smoking (ANY) within the last year or a history of >/=10 pack years

- Previous immunotherapy treatment with cat allergen within the previous 10 yrs

- Any history of grade 4 anaphylaxis due to any cause as defined by the CTCAE grading
criteria for immunotherapy

- History of bleeding disorders or treatment with anticoagulation therapy

- Treatment with omalizumab within 6 months prior to randomization

- Currently taking any of the following medications: beta blockers; tricyclic
antidepressants; monoamine oxidase inhibitors; or anti-IgE monoclonal antibody
treatment

- Ongoing systemic immunosuppressive treatment

- History of intolerance to the study therapy, rescue medications, or their excipients

- For women of childbearing age a positive serum or urine pregnancy test with
sensitivity of <50 mIU/mL within 72 hours before the start of study therapy

- The use of any investigational drug within 6 months of randomization

- The presence of any medical condition that the investigator deems incompatible with
participation in the trial.