August 5, 2013
GSK744, an investigational integrase inhibitor, and TMC278 LA (a long-acting, injectable form of the NNRTI rilpivirine [Edurant]) both showed safety and efficacy when administered in once-monthly or once-quarterly doses, according to a study presented at IAS 2013. There were no drug-related serious adverse events and all adverse events were either mild or moderate.
The phase 1 study, conducted by GlaxoSmithKline and Janssen, assessed the safety, tolerability, and pharmacokinetics of GSK744 (when given intramuscularly or subcutaneously) in conjunction with TMC278 LA (injected intramuscularly). The researchers enrolled 47 HIV-uninfected individuals (17 female and 30 male) with a median age of 39.5. Thirty-five were white, 10 black, and two of another race.
All patients were given an oral lead-in of GSK744 (also known as S/GSK1265744) at 30 mg/day for 14 days, followed by a week-long break, to assess safety and tolerability. Seven of the 47 patients discontinued the oral GSK744 because of non-drug-related adverse events or dizziness. The remaining 40 were given an 800-mg "loading dose" of GSK744 through intramuscular injection, and then randomized into four cohorts.
All four cohorts showed relevant plasma concentrations of the drugs within three days, meaning concentration levels were high enough to be considered effective. Between doses, concentration levels remained well above 90% inhibitory concentration (IC90) for both GSK744 and TMC278. The plasma concentration levels of TMC278 LA were comparable to taking oral rilpivirine at 25 mg/day.
Three people withdrew during the injection phase, two for non-drug-related adverse events and one for self-limited rash. The most common event not related to injection site reaction (ISR) was headache, but there were no serious adverse events (grade 4 or higher). Local ISRs were common, but generally well tolerated and self-limited.
The researchers concluded that injections of GSK744 with TMC278 LA were safe and generally well tolerated in healthy adults, with monthly or quarterly doses showing long-lasting and effective levels of plasma concentrations. Further study and clinical evaluation will be needed.
While these drugs are still in early stages of study, the hope is that they can act as long-lasting PrEP (pre-exposure prophylaxis) or effective treatment for HIV-infected patients that could replace daily pills.
Warren Tong is the research editor for TheBody.com and TheBodyPRO.com.
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