This randomized, observer-blinded, placebo-controlled study will assess the safety, tolerability, pharmacokinetics and pharmacodynamics of RO5469754 in healthy volunteers. Subjects will be randomized in cohorts to receive single ascending intravenous or subcutaneous doses of RO5469754 or placebo. In-clinic period will be from Day -1 to Day 4, with a safety follow-up of 15 weeks after dosing.

Inclusion Criteria:

• Healthy male or female volunteers, 18 to 64 years of age, inclusive
• Body mass index (BMI) 18 to 32 kg/m2
• Women of child-bearing potential and their partners must be willing to use two highly effective forms of contraception, one of which must be a barrier method, for the entire duration of the study (through study discharge) or for up to five half-lives after the last dose
• Male subjects with female partners of child-bearing potential must be willing to use a condom during sexual activity for the duration of the study (through study discharge) or for up to five half-lives after the last dose

Exclusion Criteria:

• Pregnant or lactating women
• Positive test for drugs of abuse (including ethanol) as per local standards
• Willing to comply with a non-smoking policy during the in-clinic part of the study (Day -1 until discharge on Day 4)
• Positive for hepatitis B, hepatitis C or HIV infection
• History or presence of clinically significant disease or condition
• Participation in an investigational drug or device study within 60 days prior to dosing
• Current (or previous history of) exposure to therapeutic or investigational monoclonal antibody or chimeric biomolecule
• Any confirmed clinically significant previous allergic drug reaction, or history of anaphylaxis