Background SOF 400 mg and LDV/SOF 90/400 mg are approved HCV treatment in adults and adolescents. Pharmacokinetic (PK) data indicates that SOF 200 mg and LDV/SOF 45/200 mg are appropriate doses in children 6 to Methods HCV-infected children (3 to Results All but 1subject completed IPK assessments. At baseline, median age and weight for subjects was 5 y and 17 kg in SOF+RBV PK lead-in (N=11) and 5 y and 20 kg in LDV/SOF subjects (N=14). The predefined PK criteria were met as GS-331007 and LDV AUCtau were within the 50–200% boundaries as compared with the adult Phase 2/3 population (table 1). The GS-331007 Cmax (SOF+RBV) was modestly higher; these increases are not considered clinically relevant based on established exposure-safety analyses. SOF concentrations were within the range of those observed in the SOF and LDV/SOF adult Phase 2/3 population (data not shown). Conclusions SOF 200 or 150 mg or LDV/SOF 45/200 or 33.75/150 mg, for subjects ≥17 kg or