Estimating the benefit of an HIV-1 vaccine which reduces viral load set point

1. Estimating the benefit of an HIV-1 vaccine which reduces viral load set point Swati Gupta, DrPH, MPH Merck Research Laboratories Epidemiology Department DIMACS Workshop on Facing the Challenge of Infectious Disease in Africa September 25-27th, 2006

2. Adults and children estimated to be living with HIV, 2005 Eastern Europe & Central Asia 1.5 million [1.0 – 2.3 million] Western & Central Europe 720 000 [550 000 – 950 000] North America 1.3 million [770 000 – 2.1 million] East Asia 680,000 [420 000 – 1.1 million] North Africa & Middle East 440 000 [250 000 – 720 000] Caribbean 330 000 [240 000 – 420 000] South & South-East Asia 7.6 million [5.1 – 11.7 million] Sub-Saharan Africa 24.5 million [21.6 – 27.4 million] Latin America 1.6 million [1.2 – 2.4 million] Oceania 78 000 [48 000 – 170 000] Total: 38.6 (33.4 – 46.0) million

3. Global estimates for adults and children, 2005 • People living with HIV • New HIV infections in 2005 • Deaths due to AIDS in 2005 38.6 million [33.4 – 46.0 million] 4.1 million [3.4 – 6.2 million] 2.8 million [2.4 – 3.3 million] Source: UNAIDS, 2006 Report on the Global AIDS Epidemic

4. Over 11,000 new HIV infections a day in 2005 • More than 95% are in low and middle income countries • About 1,500 are in children under 15 years of age • About 10,000 are in adults aged 15 years and older of whom: • Almost 50% are among women • Over 40% are among young people (15-24) Source: UNAIDS, 2006 Report on the Global AIDS Epidemic

5. 50 40 30 20 10 0 1985 1990 1995 2000 2005 Year Estimated number of people living with HIV globally, 1985–2005 Estimated number of people living with HIV, millions Source: UNAIDS, 2006 Report on the Global AIDS Epidemic

6. Estimated number of people living with HIV in sub-Saharan Africa, 1985–2005 30 25 20 15 10 5 0 1985 1990 1995 2000 2005 Year Source: UNAIDS, 2006 Report on the Global AIDS Epidemic

7. Estimated number of adults and children living with HIV by region, 1985–2005 45 40 35 30 25 20 15 10 5 0 1985 1990 1995 2000 2005 Year Oceania North Africa & Middle East Eastern Europe & Central Asia Latin America and Caribbean North America and Western Europe Asia Sub-Saharan Africa Estimated number of people living with HIV by region, millions Source: UNAIDS, 2006 Report on the Global AIDS Epidemic

8. A global view of HIV infection 38.6 million people [33.4‒46.0 million] living with HIV, 2005 Source: UNAIDS, 2006 Report on the Global AIDS Epidemic

9. HIV prevalence in adults in Asia, 1990−2005 Source: UNAIDS, 2006 Report on the Global AIDS Epidemic

10. HIV prevalence in adults in Latin America and the Caribbean, 1990−2005 Source: UNAIDS, 2006 Report on the Global AIDS Epidemic

11. HIV prevalence in adults in sub-Saharan Africa, 1990−2005 Source: UNAIDS, 2006 Report on the Global AIDS Epidemic

12. Comparison of 2003 and 2005 data 25 25 25 20.0 20 20 20 15 15 15 9.2 9.0 10 10 10 7.6 7.0 5 5 5 3.3 0 0 0 2003 2005 2003 2005 2003 2005 Access to mother-to-child prevention services (all pregnant women) Coverage of HIV-infected mothers who received antiretroviral prophylaxis Coverage of antiretroviral therapy Percent Percent Percent Sources: WHO/UNAIDS (2006). Progress on global access to HIV antiretroviral therapy: a report on “3 by 5” and beyond; USAID et al. (2006). Coverage of selected services for HIV/AIDS prevention, care and support in low and middle income countries in 2003 and 2005.

13. Comparison of 2003 and 2005 data (cont.) 60 60 56.0 50 50 40 40 35.0 30 30 25.0 19.7 20 20 12.0 9.3 7.0 10 10 6.3 4.6 3.0 1.0 0.0 0 0 Kenya Namibia Uganda Kenya Namibia Uganda Coverage of HIV-infected mothers who received antiretroviral prophylaxis Coverage of antiretroviral therapy 2003 2005 Sources: Individual country reports (2005).

14. Benin 2001 Botswana 2001 Burkina Faso 2003 Cameroon 2004 Chad 2004 Ghana 2003 Guinea 2005 Kenya 2003 Lesotho 2004 Madagascar 2003 Malawi 2004 Mali 2001 Mozambique 2003 Nigeria 2003 Rwanda 2004 Senegal 2005 United Republic of Tanzania 2003 Uganda 2004 Zambia 2003 Female Male 15–24 year olds reporting condom use during sexual intercourse with a non-regular partner, Sub-Saharan Africa, 2001–2005 Countries with date of survey indicated, percent 0 10 20 30 40 50 60 70 80 90 100 Sources: Demographic Health Surveys; HIV/AIDS Indicator Surveys (2001-2005).

15. Injecting drug users Median percentage of most-at-risk populations reached with prevention programs and those who received HIV testing in the last 12 months and who knew their results 50 42% (n=13) 40 38% (n=9) 30 28% (n=10) % 23% (n=10) 19% (n=10) 20 17% (n=10) 10 0 Percentage who received HIV testing and who knew their results Percentage reached with prevention programs Sex workers Men who have sex with men Source: UNAIDS, 2006 Report on the Global AIDS Epidemic

16. 25 years of AIDS 12 13 10 7 15 14 1 16 8 6 5 2 4 3 9 People living with HIV 1 First cases of unusual immune deficiency are identified among gay men in USA, and a new deadly disease noticed 50 9 In 1991-1993, HIV prevalence in young pregnant women in Uganda and in young men in Thailand begins to decrease, the first major downturns in the epidemic in developing countries 45 2 Acquired Immune Deficiency Syndrome (AIDS) is defined for the first time 40 3 The Human Immune Deficiency Virus (HIV) is identified as the cause of AIDS 10 Highly Active Antiretroviral Treatment launched 35 4 In Africa, a heterosexual AIDS epidemic is revealed 11 Scientists develop the first treatment regimen to reduce mother-to-child transmission of HIV 5 The first HIV antibody test becomes available 30 11 6 Global Network of People living with HIV/AIDS (GNP+) (then International Steering Committee of People Living with HIV/AIDS) founded Children orphaned by AIDS in sub-Saharan Africa 12 UNAIDS is created 25 13 Brazil becomes the first developing country to provide antiretroviral therapy through its public health system Million 20 7 The World Health Organisation launches the Global Programme on AIDS 14 The UN General Assembly Special Session on HIV/AIDS. Global Fund to fight AIDS, Tuberculosis and Malaria launched 15 8 The first therapy for AIDS – zidovudine, or AZT -- is approved for use in the USA 10 15 WHO and UNAIDS launch the "3 x 5" initiative with the goal of reaching 3 million people in developing world with ART by 2005 5 16 Global Coalition on Women and AIDS launched 0 2005 1980 1985 1990 1995 2000 Source: UNAIDS, 2006 Report on the Global AIDS Epidemic

17. Background • The continued rapid spread of HIV-1 globally highlights the need for urgent new preventive measures • A safe and effective prophylactic vaccine for human immunodeficiency virus (HIV) is now widely thought to be critical in controlling the pandemic, especially in developing countries • To understand why there is still no effective HIV vaccine 25 years after the first case of AIDS was diagnosed requires understanding a bit of background about the virus and how our immune systems interact with the virus

18. Background (continued) • Innate immunity • “non-specific” or “non-adaptive” responses • Acquired immunity • Humoral immunity • Coordinated by B cell/antibody responses which have receptors on their surface that allow them to connect with and capture pathogens as they circulate freely in the blood • Examples of vaccines which lead to the production of neutralizing antibodies: measles, polio, and hepatitis B vaccines • Unfortunately, the induction of neutralizing antibodies against HIV is a difficult task • Results of first large scale Phase III efficacy trial

19. Background(continued)

20. Background (continued) • Acquired immunity • Humoral immunity • Cellular immunity • Coordinated by CD4+ T cells and CD8+ “killer” T cells that identify and kill pathogen infected cells • Vast majority of AIDS vaccines in clinical trials have been designed to induce cellular immune responses • Implications of cell mediated immunity (CMI)-based responses to HIV infection in the context of vaccine development

21. Background(continued) • Cell mediated immunity (CMI)-based HIV vaccines • Current CMI-based vaccines are expected to either prevent infection or contain post-infection viral load set-point in people who become infected despite vaccination

22. Viral load set point after infection

23. Background(continued) • Natural history of HIV Infection in the context of CMI-based HIV vaccines Lyles et al.; JID 2000;181:872-880

24. Background(continued) • Natural history of HIV Infection in the context of CMI-based HIV vaccines • Current cell mediated immunity (CMI)-based vaccines are expected to either prevent infection or contain post-infection viral load set-point in people who become infected despite vaccination • The time to events in the course of HIV disease progression could be extended • Magnitude of the potential clinical benefit of a vaccine which reduces viral load setpoint is largely unknown

25. Background(continued) • Candidate vaccines designed to induce cell-mediated immune responses against human immunodeficiency virus-1 (HIV-1) are currently being developed • These vaccines are expected to provide either “complete” or “partial protection” from HIV-1 infection. • “Complete protection” refers to preventing establishment of HIV-1 infection • “Partial protection” refers to an attenuation of the course of HIV-1 infection due to suppression of viral replication • Vaccines which provide “partial protection” are likely to be associated with reduced viral set points after infection

26. Background(continued) • Plasma viral load measured up to 18 months after seroconversion strongly predicts the risk of disease progression • Therefore, a vaccine capable of reducing viral load set point could provide important clinical benefit such as delaying the onset of AIDS or the need for antiretroviral therapy • Using data collected from a cohort study on the natural history of HIV-1 infection, we modeled the potential impact of a vaccine which would reduce viral set point after infection.

27. Methods • Study Population • Multicenter AIDS Cohort Study (MACS) • On-going (initiated in 1983), prospective cohort study of HIV infection in men who have sex with men • 5622 participants enrolled before 2001 • 4 sites in Baltimore/Washington, Chicago, Los Angeles and Pittsburgh • Participants were either HIV-1 seronegative or HIV-1 seropositive but without a clinical AIDS diagnosis at enrollment • Participants seen every 6 months • Study visits include the following: • Behavioral and medical history • Physical Exam • Blood collection

28. Methods(continued) • Role of MACS in describing the epidemiology of HIV infection • Incidence and risk factors of HIV infection • Natural history of HIV infection • Time to AIDS and death (survival times) • Prognostic value viral load characterized • Efficacy of combination/HAART therapies on individual and population levels • Adverse events / toxicities of therapies • Role of genetic markers on infection and disease progression Source: UNAIDS, 2006 Report on the Global AIDS Epidemic

29. Methods (continued) • Inclusion Criteria for analyses • HIV-1 seronegative at enrollment into the MACS and seroconverted during the follow-up period • One year or less between their last HIV-1 seronegative (LN) and first HIV-1 seropositive (FP) visits (seroconversion dates were calculated as the midpoint between the LN and FP visits) • HIV-1 RNA measurement available at 3, 9 or 15 months post-seroconversion • Early HIV-1 RNA measurement was required to precede the initiation of any antiretroviral therapy

30. Methods (continued) • Data Analysis • Early HIV-1 RNA measurements were examined to determine if there were in any trends in viral load soon after seroconversion. • Lognormal parametric regression models were used to investigate the relationship between viral load set point and time to the following outcome variables: • Clinical AIDS (defined as an opportunistic illness) • CD4 cell count level (<350 cells/mm3, <200 cells/mm3) • Loss of virological control ( HIV-1 RNA >=55,000 copies/mL) • Clinical indication for initiation of antiretroviral therapy (HIV-1 RNA >=55,000 copies/mL or CD4+ T-cell count <350 cells/mm3 or diagnosis of an OI) • Relative times to events of interest were estimated for those with viral load set points of 30,000 copies/mL (reference group) vs. those with lower viral set points.

31. Results TABLE 1. Viral RNA and CD4+ T-cell count measurements following seroconversion HIV-1 RNA (copies/mL) CD4+ T-cell count (cells/mm3) Months post seroconversion (PSC) n Median (IQR) Geometric mean (SD)* n Median (IQR) Mean (SD) ~3 months PSC 340 28,832 (7,887, 90,441) 22,387 (6.8) 324 738 (548, 944) 780 (332.6) ~9 months PSC 311 27,986 (7,903, 63,861) 19,815 (5.9) 298 639 (460, 847) 681 (291.1) ~15 months PSC 275 25,495 (9,238, 58,478) 20,797 (4.9) 271 587 (450, 792) 643 (289.4) * The standard deviation of the geometric mean represents 10 to the x, where x is the standard deviation of the log10 HIV RNA

32. Results (continued) TABLE 2. Demographic statistics for 311 seroconverters with HIV RNA available at 9 months post- seroconversion * IQR = Interquartile range

33. Event 0.50-log reduction: HIV-1 RNA = 9,487 0.75-log reduction: HIV-1 RNA = 5,335 1-log reduction: HIV-1 RNA = 3,000 1.25-log reduction: HIV-1 RNA = 1,687 Median time to event (years) Reference group HIV-1 RNA=30,000 Median Time to event (years) Relative time (95% CI) Median Time to event (years) Relative time (95% CI) Median Time to event (years) Relative time (95% CI) Median Time to event (years) Relative time (95% CI) No. free of event at set point, No. of, events AIDS (defined as diagnosis of an OI) (310, 93) 8.4 11.9 1.4 (1.3, 1.6) 1.7 (1.5, 2.0) 16.9 2.0 (1.6, 2.5) 20.2 2.4 (1.9, 3.2) 14.2 CD4+ T-cell count < 200 cells/mm3 (298, 95) 6.1 8.1 1.3 (1.2, 1.5) 9.2 9.2 10.6 1.7 (1.4, 2.1) 12.1 2.0 (1.5, 2.6) 1.5 (1.3, 1.8) CD4+ T-cell count < 350 cells/mm3 (263, 133) 3.4 4.5 1.3 (1.2, 1.5) 5.2 1.5 (1.3, 1.8) 5.9 1.7 (1.4, 2.1) 6.8 2.0 (1.6, 2.6) 2.4 (1.6, 3.4) HIV-1 RNA > 55,000 copies/mL (149, 59) 2.4 4.3 1.8 (1.4, 2.2) 5.7 7.6 3.1 (1.9, 5.0) 10.1 4.1 (2.3, 7.5) Clinical indication for initiation of anti-retroviral therapy** (137, 76) 1.9 2.7 1.4 (1.2, 1.7) 3.3 1.7 (1.3, 2.2) 3.9 2.0 (1.5, 2.9) 4.7 2.4 (1.6, 3.7) TABLE 3. Median and relative time (RT)* to clinical events for cohort participants with HIV-1 RNA of 30,000 copies/mL compared with a 0.50, 0.75, 1.00 and 1.25 log reduction in HIV-1 RNA at 9 months post-seroconversion, using Log-Normal Models (n=311) • Relative time is a calculated as the ratio of time to each event for the comparison HIV-1 RNA categories (9487, 5335, 3000, 1687 copies/mL) and • reference group category of 30,000 copies/mL. • ** Clinical indication for initiation of antiretroviral therapy defined as HIV-1 RNA > 55,000 copies/mL or CD4+ T-cell count < 350 cells/mm3 or OI

34. Conclusions • The time to key clinical events in the course of HIV-1 disease progression was significantly extended for those with initial HIV-1 RNA 0.5-1.25 log10 copies/mL lower than the reference group • For those with an initial viral load measurement of 3,000 vs. 30,000 copies/mL, the relative time to study endpoints was approximately double or higher • This applies to those events which occur earlier in HIV disease progression, such as a CD4 cell count below 350 cells/mm3 • A viral set point of no more than approximately 10,000 copies/mL is still associated with at least a 30% extension in the time to clinical events in HIV disease progression compared to the reference group

35. Conclusions(continued) • This analysis, based upon natural history data, provides a context for understanding the expected long term clinical value of a reduction in viral set point • These findings may be useful in predicting the clinical benefit of HIV-1 vaccines that are currently in clinical trials

36. Limitations • The MACS does not include women. • Additional analyses should be conducted to determine if relative times to events of interest are similar in men and women • The MACS participants are predominantly infected with clade B HIV-1. • Since the natural history of HIV-1 infection may differ by infecting clade, it will be important to conduct similar analyses in populations infected with non-clade B subtypes. • A number of studies have shown the association between specific HLA alleles and disease resistance or progression. • Future analyses of the effect of viral load set point on time to events in HIV disease progression could account for individual HLA types.

37. Acknowledgments • Data in this poster were collected by the Multicenter AIDS Cohort Study (MACS) with centers (Principal Investigators) at The Johns Hopkins University Bloomberg School of Public Health (Joseph B. Margolick, Lisa Jacobson), Howard Brown Health Center and Northwestern University Medical School (John Phair), University of California, Los Angeles (Roger Detels), and University of Pittsburgh (Charles Rinaldo).   • The MACS is funded by the National Institute of Allergy and Infectious Diseases, with additional supplemental funding from the National Cancer Institute and the National Heart, Lung and Blood Institute.   UO1-AI-35042, 5-MO1-RR-00722 (GCRC), UO1-AI-35043, UO1-AI-37984, UO1-AI-35039, UO1-AI-35040, UO1-AI-37613, UO1-AI-35041.  

39. Discussion • HIV-1 RNA measurements were relatively similar at 3, 9, and 15 months after seroconversion (range of geometric means: 19,815-22,387). • Compared with a viral set point of 30,000 copies/mL, a viral set point of 3,000 copies/mL was associated with an additional 2.5 years before CD4 count fell to 350 cells/mm3 - a common threshold for initiating antiretroviral therapy. • The median time to HIV-1 RNA >= 55,000 copies/mL, commonly defined as the loss of virological control, was three times longer for those with viral load set points of 3,000 compared to those with viral load set points of 30,000 copies/mL.

40. Discussion (continued) • Compared to those with an HIV RNA of 30,000 copies/mL at set point, an HIV RNA of 10,471 (4.02 log10) would be required to significantly reduce the hazard of progressing to a clinical indication to initiate antiretroviral therapy within 3 years by 25%.

41. People in sub-Saharan Africa on antiretroviral treatment as percentage of those in need, 2002–2005 2002 2003 2004 2005 Source: WHO/UNAIDS (2005). Progress on global access to HIV antiretroviral therapy: An update on “3 by 5.”

42. Impact of AIDS on life expectancy in five African countries, 1970–2010 70 65 60 Botswana 55 South Africa Life expectancy at birth (years) 50 45 Swaziland 40 35 Zambia 30 Zimbabwe 25 20 1970–1975 1980–1985 1990–1995 2000–2005 1975–1980 1985–1990 1995–2000 2005–2010 Source: United Nations Population Division (2004). World Population Prospects: The 2004 Revision, database.

43. Impact of three scenarios on HIV infection in sub-Saharan Africa, 2003–2020 5.0 4.0 Number of new HIV infections (millions) 3.0 2.0 1.0 0.0 2003 2005 2010 2015 2020 Year Baseline Treatment-centered Prevention-centered Comprehensive response Source: Salomon JA et al. (2005). Integrating HIV prevention and treatment: from slogans to impact

44. 50 45 40 35 30 25 20 15 10 5 0 Figure 3. Percentage of Adenovirus 5 neutralizing antibody titers by country Negative 18 - 200 201-1000 > 1000 Brazil Cameroon Malawi S. Africa Thailand Dominican Republic International Sites US

45. Worldwide Distribution of HIV-1 Clades (Subtypes)* A, B, AB, Other B, Other G B A F B, Other B B, AE B, BC B, G, Other G, Other B, O C C B, Other O A, Other A AE, B, Other B, AE, Other AG All G, Other A,C,D B, F, Other Legend C B B B dominant + Another C, Other C B, F O B, AE A B, C All Other Note: *Dominant clades are bolded above; All regions have multiple clades in their populations

46. 100 90 80 70 60 50 40 30 20 10 0 Gag Nef Pol1 Pol2 Rev Tat Figure 4. Frequencies of subjects who were responders on ELISPOT assays in 340 HIV-positive subjects US (n=16) Brazil (n=50) Thailand (=77) South Africa (n=48) Malawi (n=40) Botswana n=43) Cameroon (n=51) Dominican Republic (n=15)