Concert Pharmaceuticals announced that it has initiated a Phase 1b clinical study with CTP-518, its investigational oral protease inhibitor for the treatment of HIV infection. Participants in this randomized, double-blind, placebo-controlled study will receive CTP-518 or placebo for 14 days. This study is intended to establish the pharmacokinetic enhancing effect of deuterium incorporation in CTP-518, and to determine whether CTP-518 dosed once-daily can maintain blood levels expected to be sufficient to suppress HIV replication when used as part of a standard three drug combination regimen. More specifically, this study will be used to assess the ability of CTP-518 to maintain acceptable therapeutic blood concentrations without a boosting agent such as ritonavir.

CTP-518 is a novel HIV protease inhibitor developed from Concert’s deuterium chemistry platform by replacing certain key hydrogen atoms of atazanavir with deuterium. In preclinical studies, the antiviral potency of atazanavir was fully retained but with markedly slower hepatic metabolism, providing an increase in half-life and plasma trough levels. The preclinical studies indicated that CTP-518 could potentially avoid the need for a protease inhibitor boosting agent such as ritonavir.

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