258. Phase I/IIa Study of TT-034, a DNA-Directed RNA Interference (ddRNAi) Agent Delivered as a Single Administration for the Treatment of Subjects with Chronic Hepatitis C Virus (HCV)
Authors: Keyur Patel, Georgina Kilfoil, David L. Wyles, Susanna Naggie, Eric Lawitz, Stephen Bradley, Per Lindell, David Suhy
Journal: Molecular Therapy (2016)

Background: TT-034, a RNAi-based gene therapy product for the treatment of HCV infection, is comprised of a self-complementary recombinant DNA packaged in an adeno-associated virus capsid (AAV8) for transduction of hepatocytes. TT-034 directs the continuous expression of three independent short hairpin RNAs (shRNAs) that simultaneously target three well-conserved sequences located in the 5' UTR and NS5B regions of the HCV genome. At clinically relevant doses in non-human primates (NHP), a single intravenous infusion of TT-034 resulted in almost complete transduction of hepatocytes and long-term shRNA expression for 180 days (the duration of the experiment). Intended as a one-time treatment, the dosing with TT-034 is the first time that a non-withdrawable DNA-directed RNAi-based gene therapy has been used in man. Methods: The ongoing phase I/IIa open label dose-escalating trial is enrolling chronic HCV genotype 1 patients without cirrhosis. Patients receive a single intravenous infusion of TT-034 at one of five dose levels. 21 days after dosing, a liver biopsy is collected to assess TT-034 DNA levels and shRNA expression by Quantitative PCR (QPCR). Results: Eight subjects have received a single dose of TT-034 at 4.00E10, 1.25E11, 4.00E11 or 1.25E12 vg/kg. Additional subjects may be enrolled in dose cohorts of 1.25E12 or at doses as high as 4.00E12 vg/kg. To date there have been no treatment-related serious adverse events in the study. Once administered, TT-034 clears from serum within the first week post dosing. No long term TT-034 shedding has been detected in the urine, stool, semen, or sputum. QPCR measurement of TT-034 DNA levels from the liver biopsies are similar to those reported in NHP models. Specifically, two patients administered a dose of 4.00E10 vg/kg resulted in either 0.01 or 0.02 copies of TT-034 DNA per cell, the equivalent of 1-2% hepatocyte transduction. At a dose of 1.25E11 vg/kg, substantially higher levels of TT-034 were detected in the three subjects, yielding 0.48, 3.65 and 10.44 copies per cell respectively. Some variability in transduction was noted at a dose of 4.00E11 vg/kg, with the two subjects yielding 17.74 and 1.01 copies per cell. We continue to explore the factors influencing this variability, however these data suggest that a significant portion of the hepatocytes may have been transduced in one cohort 3 subject. QPCR analysis of the three anti-HCV shRNAs performed on RNA isolated from the biopsies confirms concomitant, dose dependent expression. From the subject with the highest TT-034 DNA copies per cell quantities of shRNA6, shRNA19 and shRNA22 were measured at 66, 2032, and 99 copies per cell respectively. Conclusion: These data suggest that TT-034 is well tolerated and safe in human subjects infected with HCV. Furthermore, the vector can effectively transduce hepatocytes and concurrently express three anti-HCV shRNAs.