Phase II study of the antiretroviral activity and safety of the glucocorticoid receptor antagonist mifepristone in HIV-1-infected patients

Preclinical studies have shown that the anti-glucocorticoid drug mifepristone effectively inhibits HIV replication both in vitro and in vivo. However, the drug did not demonstrate anti-HIV activity in a previous phase I/II study when administered at the daily dose of 75-225 mg. The aim of this study was to assess whether mifepristone may exert antiretroviral activity or influence immunological parameters when administered orally at daily doses of 150 or 300 mg in highly active antiretroviral therapy (HAART)-na?ve HIV-infected patients. We performed an open label non-randomized phase II study that included 26 patients who underwent 28 days of once daily oral administration of 150 (12 subjects) or 300 mg (14 subjects) of mifepristone. A total of 3 patients dropped out of the study, respectively 1 in the 150 mg dose group and 2 in the 300 mg dose group. The main hemato-chemical alterations reported were hypokalemia and increase in the blood levels of cortisol, especially in those patients that received mifepristone at the dose of 300 mg/day. Although we observed a trend of reduced viral load along the study in both groups, statistical significance was not achieved for either the primary nor the secondary endpoints. In summary, mifepristone treatment was well-tolerated but it failed to significantly influence viro-immunological parameters in HAART-na?ve HIV-infected patients.