The primary objective of the chronic toxicology studies is to assess the safety of R7128 when given for six months. Roche triggered a $7.5 million milestone payment to Pharmasset by initiating these studies.
R7128 is a polymerase inhibitor being developed for the treatment of chronic hepatitis C. R7128 is a prodrug of PSI-6130, which demonstrated potency in preclinical studies, according to Pharmasset. PSI-6130 is a pyrimidine nucleoside analog inhibitor of HCV RNA polymerase, an enzyme that is necessary for hepatitis C viral replication.
Results from an oral single ascending dose study in 24 healthy male volunteers showed that PSI-6130 was generally well tolerated with no serious adverse events in doses up to 3000 mg.
The Phase I clinical trial is a multiple center, observer-blinded, randomized and placebo-controlled study to investigate the pharmacokinetics, pharmacodynamics, safety, tolerability and food effect of R7128 in healthy volunteers and in patients chronically infected with HCV genotype I.