What if a Drug that Was Developed to Treat HIV Infection Could Actually Help to Cure It? Mark A Wainberg McGill University AIDS Centre Jewish General Hospital Montreal, Quebec, Canada

InI Dissociation from WT IN-DNA Complex at 37°C DTG RAL EVG 1.0 INI koff (s-1) t1/2 (h) DTG 2.7 x 10-6 71 RAL 22 x 10-6 8.8 EVG 71 x 10-6 2.7 0.8 0.6 Relative binding 0.4 0.2 0.0 Key point DTG dissociated more slowly from the WT-IN-DNA complex at 37oC with a dissociation rate of 2.7x10–6 s–1 and a dissociative half life (t1/2) of 71 hours, significantly longer than t1/2 for RAL (8.8 hours) and EVG (2.7 hours; p<0.0001). Additional notes Both RAL and EVG dissociated more quickly than DTG (p<0.0001) with Koff values of 22 x 10-6 s-1 for RAL and 71 x 10-6 s-1 for EVG. Slow dissociation occurs as the molecular architecture of INI-DNA complex is resistant to substitutions due to stronger co-ordination bonds holding the complex together. This may lead to improvements in efficacy, or reduced probability of resistance emergence. Reference Hightower, KE, et al. Antimicrob Agents Chemother 2011; 55(10): 4552–59 10 20 30 40 50 60 Time (h) DTG dissociated more slowly from a WT IN-DNA complex at 37°C compared with RAL and EVG DTG dissociation was eight times longer than RAL and 26 times slower than EVG Koff , dissociation rate; t1/2h, half-life in hours Adapted from Hightower KE, et al. Antimicrob Agents Chemother 2011;5:4552–9

The R263K mutation decreases integrase activity in cell-free assays Quashie, Mesplède et al., Journal of Virology, 2012

The addition of H51Y to R263K further decreases IN strand transfer activity B

The combination of H51Y and R263K negatively impacts viral fitness

Virus Weeks 8-15   WT M184V H51Y M184I R263K H51Y/R263K None G118R H51Y/G118R

Replication Capacity of HIV Containing Various Combinations of INSTI Resistance Mutations % fitness E92Q ≈ 75% Y143 ≈ 72% Q148 N155 R263K ≈ 70% G140/Q148 ≈ 95% R263K/H51Y ≈ 25% R263K/E138K R263K/Q148R R263K/Y143C R263K/E92Q

Selection of HIV-1 containing R263K with RAL and EVG Time (weeks) Initial Mutation Acquired Mutations EVG 30 R263K M50I, T66I RAL --- 38 T97A/T, Y143H/Y, Q148K/Q 41 T97A, Y143R

No compensatory mutations in regard to DTG resistance and viral fitness have developed over more than three years in culture.

Hypotheses Viruses resistant to DTG via the R263K pathway should not be transmissible because of low viral fitness A series of judicious treatment interruptions followed by the use of DTG could conceivably convert viruses that are archived into attenuated forms. This subject should first be addressed in suitable animal models.

Acknowledgements Bluma Brenner Hongtao Xu Dimitri Coutsinos Jerry Zaharatos Maureen Oliveira Thibault Mesplède Peter Quashie

Thanks to CIHR and CANFAR