This first-in-human (FIH) study is a randomized, double-blinded, placebo-controlled, ascending dose study to investigate the safety, tolerability, and pharmacokinetics of XmAb7195 in adult healthy volunteers and in adult subjects with elevated IgE levels.

Inclusion Criteria:

• Adult males and females 18 to 50 years of age
• Parts 1 and 3: Healthy subjects with no clinically significant abnormality identified on medical or laboratory evaluation and no history of any clinically significant disorder, condition, or disease that would pose a risk to subject safety or interfere with the study evaluation, procedures, or completion;
• Part 2: Otherwise healthy male and female subjects with a history of allergic rhinitis and/or allergic conjunctivitis and/or atopic dermatitis with an elevated serum IgE
• Subjects who are able and willing to give written informed consent;
• Subjects who have the ability to complete all study assessments;
• Subjects who are willing to forego other forms of experimental treatment during the study.

Exclusion Criteria:

• Subjects who have a clinically relevant history or presence of respiratory, gastrointestinal, renal, hepatic, hematological, lymphatic, neurological, cardiovascular, psychiatric, musculoskeletal, genitourinary, immunological, dermatological, connective tissue diseases, or disorders (other than allergic rhinitis and/or conjunctivitis and/or atopic dermatitis in Part 2) that would pose a significant risk to subject safety or significantly interfere with the study evaluation, procedures, or completion
• Subjects who are positive for hepatitis B surface antigen (HBsAg), hepatitis C virus (HCV) antibody and/or human immunodeficiency virus (HIV) Type I or Type II tests at Screening;
• Subjects who do not agree to use medically acceptable methods of contraception (as defined in the protocol);
• Subject is pregnant or breast feeding, or planning to become pregnant within 3 months of administration of XmAb7195;
• Subjects who have used any investigational drug in any clinical trial within 8 weeks prior to admission (Day -1), or have used an experimental monoclonal antibody;
• Subjects with prior exposure to a monoclonal antibody;
• Subjects with a history of anaphylaxis;
• Subjects who have received live vaccines ≤ 3 months from Screening;