A Study to Investigate the Safety, Tolerability and Pharmacokinetics of RO6889678 and the Combination of RO6889678 With Ritonavir in Healthy Participants

This study is a single-center, double-blind, randomized, placebo-controlled, single-ascending dose (SAD) and multiple-ascending dose (MAD) study that will evaluate the safety, tolerability and pharmacokinetics (PK) of RO6889678 and the combination of RO6889678 with Ritonavir (RTV) following oral administration in healthy volunteers. The effect of food on the PK of RO6889678 and the effect of multiple dosing of RO6889678 and the combination of RO6889678 with RTV on the PK of a single oral microdose of midazolam will be evaluated. Healthy participants will be screened up to 28 days before randomization and sequentially enrolled into SAD and MAD unboosted and RTV-boosted cohorts, then randomly assigned to RO6889678 or matching placebo. In RTV-boosted cohorts participants will take RO6889678 in combination with RTV. To explore the effect of food on RO6889678 PK, a cohort of volunteers will participate in a two-period food effect sub-study. Participants enrolled in the MAD cohorts will be given an oral microdose of midazolam before and after the repeat treatment with RO6889678 to evaluate the drug-drug interaction potential of RO6889678.