SUSCEPTIBILITY OF HUMAN CYTOMEGALOVIRUS TO CIDOFOVIR IS UNCHANGED AFTER LIMITED IN-VIVO EXPOSURE TO VARIOUS CLINICAL REGIMENS OF DRUG

Cidofovir (S)-3-hydroxy-2-(phosphonomethoxy)propyl]cytosine] susceptib ility among 29 paired pre- and post-cidofovir exposure isolates from 2 2 patients enrolled in a phase I/II clinical trial, GS-92-101, was det ermined, This trial was designed to evaluate the safety and antiviral effects of cidofovir in patients with AIDS and asymptomatic shedding o f human cytomegalovirus (HCMV) in semen with no evidence of end-organ HCMV disease and no prior anti-HCMV therapy, These patients received a median cumulative dose of 30 mg/kg (range, 3-67) administered over a median of 8 weeks (range, 2-38), The IC50 values for preexposure isola tes ranged from <0.5 to 1.85 and for postexposure isolates from <0.5 t o 2 mu M. Thus, no significant changes in cidofovir susceptibilities h ave been noted for HCMV during the various regimens of cidofovir admin istrated in this clinical trial.