The purpose of the study is to assess the safety, tolerability, pharmacokinetics, and pharmacodynamic effects of single oral doses and multiple oral doses of JNJ-38877618 administered for 7 consecutive days in healthy adult male participants.

This is a randomized (individuals assigned to study treatment by chance), double-blind (individuals and study personnel will not know the identity of study treatments), placebo (an inactive substance that is compared with a drug to test whether the drug has a real effect in a clinical trial)-controlled study in healthy adult male participants aged 18 to 45 years (a single optional cohort in older healthy male participants aged 50 to 65 years may be included). If all optional cohorts are included, up to 144 participants may be enrolled. This study will consist of up to four parts. Part 1 contains up to 3 subparts: Part 1a is a double-blind, placebo-controlled, single ascending dose design (SAD) with a liquid formulation (Formulation A); Part 1b is an open-label (identity of assigned study drug will be known), single dose evaluation of a capsule formulation (Formulation B); and Part 1c is an optional open-label, single dose evaluation of a capsule formulation (Formulation C). Part 2 is the completion of the double-blind, placebo-controlled SAD after a formulation has been selected based on Parts 1a, 1b, and 1c (if applicable). Part 3 is a double-blind, placebo-controlled, multiple ascending dose design (MAD). Doses for Part 3 will be determined based on the safety, tolerability, and pharmacokinetics (study of what the body does to a drug) in Parts 1 and 2. Part 4 is an optional double-blind, placebo-controlled, single dose evaluation in older healthy male participants. Serial pharmacokinetic and pharmacodynamics (study of what a drug does to the body) samples will be collected and safety will be monitored throughout the study.

Inclusion Criteria:

• Deemed healthy on the basis of physical examination, medical history, laboratory tests, vital signs, and 12-lead electrocardiogram within protocol-defined parameters performed at screening and Day -1
• Must have good exercise tolerance
• Agrees to protocol-defined use of effective contraception
• Body Mass Index between 20 and 30 kg/m2 and body weight not less than 65 kg
• Non-nicotine user for 6 months prior to screening

Exclusion Criteria:

• Current history of clinically significant medical illness
• History of drug or alcohol abuse within 5 years
• Routine consumption of >450 mg of caffeine per day
• Recent vaccination or acute illness
• Blood donation or major blood loss within 3 months prior to study drug administration
• Use of any prescription or over-the-counter medication (not including paracetamol), or herbal medication within 2 weeks of dosing of the study drug or a proton pump inhibitor within 6 weeks prior to dosing of study drug
• Currently enrolled in an investigational study, or received an investigational drug or vaccine, or used an invasive investigational medical device within 3 months before the planned first dose of study drug
• Plans to father a child while enrolled in this study or within 3 months after the last dose of study drug
• Major surgery within 3 months before or after study participation or minor surgery within 6 weeks before screening, or 30 days after the last study drug administration
• Any condition for which, in the opinion of the investigator, participation would not be in the best interest of the participant or that could prevent, limit, or confound the protocol-specified assessments