Autologous T-cell therapy based on a lentiviral vector expressing long antisense RNA targeted against HIV-1 env gene influences HIV replication and evolution in vivo 1 Laboratory of Experimental Virology, Department of Medical Microbiology, Center for Infection and Immunity Amsterdam, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands, and 2 VIRxSYS Corporation, Gaithersburg, MD, USA Abstract no. WEPDA0205 Alexander O. Pasternak 1, Nik Korokhov 2, Ben Berkhout 1, Vladimir V. Lukashov 1, and Laurent Humeau 2 “Delivering the Promise of Genetic Medicine” TM

VRX496: a lentiviral vector encoding a 937-nt antisense RNA against a part of env gene (gp120) This vector retains the full LTRs of HIV, and, therefore, expression of the antisense is conditional upon wild type HIV infection of the cell Preclinical studies demonstrated complete inhibition of replication of heterologous HIV-1 strains in SupT1 cells and in primary CD4+ T lymphocytes from healthy donors, as well as in primary CD4+ T lymphocytes from HIV-1 infected patients

Strategy: autologous CD4+ T lymphocytes from HIV-infected subjects are transduced ex vivo with the vector, expanded, and reinfused into patients Phase I clinical trial (the first ever clinical trial with a lentiviral vector approved by FDA) demonstrated safety and tolerability of this approach (no evidence of insertional mutagenesis by deep sequencing) – Levine et al. (2006), PNAS 103(46):17372

Phase II trial: 43 HIV-infected patients who failed >1 cART regimens billion vector-modified cells were reinfused into patients Longitudinal effects of the therapy on HIV-1 env evolution were analyzed in 17 subjects sampled both pre-infusion and monthly post-infusion for 6 to 12 months Plasma-derived viral RNA from 144 samples was amplified, cloned, and the full- length gp120 coding region was sequenced in 8-10 clones for each sample

Viral Loads: Bolus 1 Dose HIV RNA per mL Days Post Infusion Transient decrease in plasma viral load was observed in some patients

Persistence: Bolus 1 Dose Days Post Infusion VRX496 Proviral Copies per 10 6 PBMCs Vector-modified cells were persisting for up to 1 year

Two AS-related factors: (a)sequence SIMilarity of the AS RNA with the targeted HIV transcripts at baseline, (b) PERsistence of the infused vector-modified cells during the follow-up period, independently and cooperatively influenced HIV replication and evolution: P<0.001P=0.003 PER low SIM low PER high SIM low PER low SIM high PER high SIM high PER low SIM low PER high SIM low PER low SIM high PER high SIM high Plasma viral load, change from baselineDegree of virus evolution from the pre-infusion to the post-infusion quasispecies (relative MRCA distances)

The degree of virus evolution from the pre-infusion to the post-infusion quasispecies negatively correlated with virus replicative fitness, assessed ex vivo by growth competition assay Low replicative fitness High replicative fitness P=0.032

Conclusion: Same AS-related factors were associated with enhanced viral evolution and with the relative decrease in plasma viral load, suggesting that selective pressure exerted by the AS causes directional viral evolution, presumably towards escape, which is associated with the fitness loss