Long-Term Efficacy and Safety Study of SCH 900237/MK-8237 in Children and Adults With House Dust Mite-Induced Allergic Rhinitis/Rhinoconjunctivitis (P05607)

Inclusion Criteria:

- History of AR/ARC to house dust of 1 year duration or more (with or without asthma)

- If female of childbearing potential, has a negative urine pregnancy test at Screening
and agrees to remain abstinent or use (or have their partner use) an acceptable
method of birth control within the projected duration of the study

- Able to read, understand and complete questionnaires and diaries

Exclusion Criteria:

- Clinically relevant history of symptomatic ARC caused by animal dander, molds and/or
cockroach (e.g. present in the home, job, daycare, etc.) or other perennial allergen

- History of symptomatic seasonal ARC and/or asthma due to an allergen to which the
participant is sensitized and regularly exposed

- Nasal condition that could confound the efficacy or safety assessments (e.g., nasal
polyposis)

- Received an immunosuppressive treatment within 3 months prior to screening

- Unstable or severe asthma, or has experienced a life-threatening asthma attack or an
occurrence of any clinical deterioration of asthma that resulted in emergency
treatment, hospitalization due to asthma, or treatment with systemic corticosteroids
(but allowing short-acting beta agonists [SABAs]) at any time within 3 months prior
to screening

- Asthma requiring high-dose inhaled corticosteroids (ICS) within 6 months prior to
screening

- History of anaphylaxis with cardiorespiratory symptoms with prior immunotherapy,
unknown cause or inhalant allergen

- History of chronic urticaria and/or angioedema within 2 years prior to screening

- History of chronic sinusitis during 2 years prior to screening

- Pregnant, breastfeeding, or expecting to conceive within the projected duration of
the study

- Previous immunotherapy treatment with any HDM allergen for more than 1 month within 5
years prior to screening

- Previous exposure to MK-8237

- Receiving ongoing treatment with any specific immunotherapy at screening

- Known history of allergy, hypersensitivity or intolerance to investigational
medicinal products (except for D. pteronyssinus and/or D. farinae), rescue
medications or self-injectable epinephrine

- Unable to meet medication washout requirements prior to screening

- Unable or unwilling to comply with the use of self-injectable epinephrine

- Business or personal relationship with investigational site personnel or Sponsor who
is directly involved with the conduct of the study

- Likely to travel for extended periods of time during the efficacy assessment period

- Participating in a different investigational study at any site during this study