Early Combination Antiretroviral Therapy in Infants

1. Impact of Early Initiation of Combination Antiretroviral Therapy on Measures of Virus in Peripheral Blood of Vertically HIV-1-Infected Children Jason Brophy1, Tae-WookChun2, Lindy Samson1, Fatima Kakkar3, Hugo Soudeyns3, Mario Ostrowski4, S. Mujib5, John Kim6, Paul Sandstrom6, Richard Harrigan7, Stanley E. Read8, Ari Bitnun8 1. Children’s Hospital of Eastern Ontario, University of Ottawa; 2. National Institute of Allergy & Infectious Diseases, National Institutes of Health, U.S.A.; 3. CHU Sainte-Justine, Université de Montréal; 4. Department of Immunology and Medicine, University of Toronto, 5. University of Toronto, Institute of Medical Sciences, Department of Medicine; 6. National HIV & Retrovirology Laboratories, Public Health Agency of Canada; 7. University of British Columbia, British Columbia Centre for Excellence in HIV/AIDS; 8. Hospital for Sick Children, University of Toronto

2. Early Combination Antiretroviral Therapy in Infants • The “Mississippi baby” received early cART – experienced a 2-year “viral remission” after stopping treatment until a recent viral rebound • raises the possibility of this as an intervention to limit reservoir establishment and enable “viral remission” • Triple cARTas HIV-post exposure prophylaxis has been routinely administered to newborns at high risk for HIV infection in our centres for many years • SickKids (Toronto), CHEO (Ottawa), and CHU Ste-Justine (Montreal)

3. Objectives • To investigate HIV-1 reservoirs in peripheral blood of HIV-1-infected children with SVS following initiation of cART within 72 hours of birth • SVS: defined as absence of detectable virus in standard viral load (VL) assay subsequent to having achieved an undetectable VL (< 50 copies/mL)

4. Methods • Retrospective review at our 3 centres of all children born to HIV-infected mothers who received triple cART within 72 hours of birth • Evaluation of HIV reservoir, immune responses, and genetic characteristics in those infected children with SVS after cART

5. Results – Retrospective Review • 136 infants received triple cART • HIV infection in 12 (8.8%) • In utero infection probable in at least 50% (n=6; HIV PCR positive within 48 hours of birth) • Timing uncertain in 50% (n=6) as testing done after 48 hrs • Four HIV-infected children achieved SVS (Cases 1-4) • Eight HIV-infected children did not achieve SVS • 6 of 8 did not achieve virologicsuppression due to poor adherence • 2 of 8 initially suppressed for 2-3 years, then experienced viral rebound after poor adherence (one during the course of our study – Case 5)

6. Reservoir Evaluation of 4 Early-Treated, HIV-Infected Children • Cases 1 to 4 had SVS from 2-7 years • All 4 remained on their original cART regimen of zidovudine, lamivudine, and nevirapine

7. Maternal Characteristics and Infant Diagnostic Testing * Non-identical twins; ** mother died soon after delivery from OI

8. Case 1 • Now 7.5 years old • Remains on same ART combination •  Has maintained an undetectable • viral load CD4 count 3940 (55%) cART initiated (day 1) HIV DNA PCR positive (day 1)

9. Case 2 • Now 7.5 years old • Remains on same ART combination •  Undetectable viral load CD4 count 1447 cells/L (28.9%; day 20) cART initiated (day 1) HIV DNA PCR positive (day 2)

10. Cases 3 & 4 CD4 count 1997 cells/L (41%, day 17) CD4 count 2663 cells/L (63%, day 15) 795 c/mL (day 12) cART initiated (day 1) HIV DNA PCR positive (day 1) cART initiated (day 1) HIV DNA PCR positive (day 1) • Now 3 years old • Remain on same ART combination and have sustained virologicsuppresSion

11. ‡ Limit of detection: 1.5 copies/mL; each assay performed on 6 mL of whole blood; § Limit of detection: 1.5 g RNA; performed in duplicate; ¶ Limit of detection; 20 copies/ml; ¥ HLA-B variation at positions associated with better virologic control (lower set-point) and specific protective amino acid substitutions are indicated in bold

12. Case 5 – Prior to Treatment Interruption

13. Case 5 CD4 2568 (46.2%) CD4 2299 (37.3%) CD4 2145 (40.0%) CD4 2584 (39.3%) CD4 1995 (38.3%) HIV DNA PCR positive (Day 4) cARTchanged (day 21) - AZT/3TC/LPV cART started (day 1) - AZT/3TC/NVP

15. Discussion • Absence of detectable HIV DNA and absent/very low levels of replication-competent virus in peripheral blood and lack of HIV-specific immune responses demonstrated in a subgroup of children initiated on cART<72 hours of birth • Suggests early cART initiation can greatly reduce HIV reservoir size • Genetic factors may also play an important role - protective HLA genotypes were found in 3 of 4 children • HLA B*58 • Sequence variation at HLA-B positions 67, 70 and 97 (associated with superior control of HIV replication) • The child with replication competent virus did not have these protective genotypic features International HIV Controllers Study, Science 2010 Lazaryan, J Virology 2006; Lazaryan, J Virology 2010

16. Discussion • Our 5th case with rapid viral rebound after interruption of therapy despite limited reservoir size demonstrates that early cART will not be effective in all patients • Multiple factors may have influenced this patient’s outcome • Baseline NNRTI resistance, sub-optimal initial regimen • Low-level detectable VL after initial suppression • This, along with late relapse of viral replication in Mississippi baby, underscore the need for better understanding of contributing factors to reservoir & viral control • Host and viral genetics • Timing and completeness of initial viral suppression • Selection of components of cART regimen in infants

17. Conclusions • Based on our study findings and other reports, early cART for HIV-infected infants clearly limits size of viral reservoir • Additional non-blood reservoir sites require investigation • The clinical significance and benefit of this remain to be seen • Accurate estimation of size of HIV viral reservoir in children is significantly impacted by limitations in collection of adequate blood volumes in children compared with adults • A prospective multi-centreobservational study (EPIC4) is underway in Canada to determine the impact of early versus later treatment on reservoir size and HIV control in children

18. Acknowledgments • The children and parents who agreed to participate in this study • The Canadian Institutes for Health Research, Canadian Association for AIDS Research, and the International AIDS Society for funding to carry out EPIC4 study

19. QUESTIONS?

20. Reservoir, Immunologic Responses and Genetics • Level of cell-associated HIV-1 DNA in CD4+ Tcells • real-time PCR • Levelofcell-associated HIV RNA • CobasAmpliprep/CobasTaqman HIV‐1 assay • Residual plasma viremia • modified CobasAmpliprep/CobasTaqman HIV‐1 assay • Presenceofreplicationcompetentvirus • levelofvirion-associated HIV RNA in culturesupernatantaftermitogenicstimulation • co-cultureassay • HIV serology; HIV-specific cell-mediated immune responses; HLA typing and CCR5 delta 32 genotyping

21. ‡ Limit of detection: 1.5 copies/mL; each assay performed on 6 mL of whole blood; § Limit of detection: 1.5 g RNA; performed in duplicate; ¶ Limit of detection; 20 copies/ml; ¥ HLA-B variation at positions associated with better virologic control (lower set-point) and specific protective amino acid substitutions are indicated in bold