Immune Discordance on Highly Active Antiretroviral Therapy Can Still be Regarded as a Therapeutic Success Nur F. Önen MD, MRCP 1, Rachel Presti MD PhD 1, E. Turner Overton MD 1, Cecilia Blair 1 and Kristin Mondy MD 1. Washington University School of Medicine, St. Louis, Missouri, USA 1. Background Risk factors for immune discordance on highly active antiretroviral therapy (HAART), and long-term clinical and immunologic outcomes remain poorly characterized. Methods Retrospective analysis of 298 HIV+ patients with baseline CD4+ T cell count <350 cells/mm 3, who initiated HAART between January 1996 and July 2006 and had viral suppression (HIV RNA <400 copies/mL pre-1999, <50 copies/mL thereafter) for ≥ 52 weeks. Discordant and concordant immune responders were defined by CD4+ T cell gains of <150 or ≥ 150 cells/mm 3 from HAART initiation through 52 weeks of viral suppression. Risk factors for poor CD4+ T cell gains were analyzed by multiple regression and long-term clinical outcome assessed. Additionally, markers of immune maturation and activation were prospectively determined for immune discordant and concordant responders (total n=45) with sustained viral suppression from the entire cohort. Results 106 (36%) patients had immune discordance. In multivariable analyses, male gender, greater number of HAART side-effects, use ever of unboosted indinavir and lower pre-HAART HIV-RNA viral load were independent predictors of immune discordance (p<0.05). Outcomes were similar between groups with regard to mean time on suppressive HAART (4.5 years), new opportunistic infections (1%) and mortality (5%). Higher levels of memory (p=0.04) and activated (p=0.08) CD4+ T cells were found among those with immune discordance, up to a mean of 6.3 years after viral suppression. Conclusions HIV+ patients with long-term immune discordance can still achieve very low morbidity and mortality, suggesting immune benefits of HAART may go beyond gains in CD4+ T cells alone. In addition, T- cell activation may blunt long-term CD4+ T cell gains. Interventions to reduce T cell activation may facilitate further CD4+ T cell recovery in this patient group. ABSTRACT Suboptimal immune reconstitution on fully suppressive highly active antiretroviral therapy (HAART) is frequently observed in clinical trials and cohort studies. Recent studies suggest that markers of immune maturation and activation may predict CD4+ T cell recovery in patients on suppressive HAART. The long-term outcomes of immune discordance on HAART in terms of overall morbidity and mortality remains poorly studied. BACKGROUND Retrospective cohort study of patients initiated on HAART between January 1996 and July Inclusion criteria HIV-1 infection, age ≥ 18 years, baseline CD4+ T cells <350 cells/mm 3 and viral suppression for ≥ 52 weeks. Definitions Discordant and concordant responders defined by CD4+ T cell gains of <150 or ≥ 150 cells/mm 3 from HAART initiation through 52 weeks of viral suppression and followed to death, virologic failure (lack of re-suppression of viremia) or study termination. Data collection Socio-demographics, clinical, medication and laboratory data. Sample collection and analysis Blood samples from immune discordant and concordant responders (total n=45) with sustained viral suppression, were obtained to determine the percentage of CD4+ and CD8+ T lymphocytes that were memory (CD45RO+) or activated (CD38+,HLADR+), using three-color flow-cytometric analysis on cryopreserved peripheral mononuclear cells. Statistics Data analyzed using SPSS version Continuous variables compared using the Student’s t-test or Mann-Whitney U test. Chi square or Fisher’s exact tests used for categorical variables. All p values were two-tailed and significant at <0.05 and potential predictive factors for immune discordance were evaluated using multivariate logistic regression analyses. RESULTS In this cohort with long-term viral suppression, immune discordance was high but morbidity and mortality remained very low. Our findings suggest immune benefits of HAART may go beyond CD4+ T cell gains. T cell-activation may blunt long-term CD4+ T cell gains and interventions to reduce T-cell activation may facilitate further CD4+ T cell recovery in patients with sub-optimal immune reconstitution. Low pre-HAART viral load was associated with immune discordance and may have implications for the use of viral load in future treatment guidelines. METHODS Contact: Nur F. Önen. Washington Univ. School of Med. Campus Box 8051, 660 S. Euclid Ave. St. Louis, MO Phone: Fax: Abstract # 952 Characteristics Discordant (n=106) Concordant (n=192) OR (95% CI)P value Male gender Age, (years) a Caucasian African American 89 (84%) 41.2 ± (55%) 38 (36%) 134 (70%) 38.2 ± (39%) 108 (56%) 2.27( ) ( ) Mode of transmission Men who have sex with men Heterosexual 56 (53%) 30 (28%) 79 (41%) 96 (50%) 1.78( ) Years since HIV diagnosis a Previous OI Prior ARV experience 9.8 ± (57%) 34 (32%) 8.3 ± (54%) 62 (32%) ( ) 1.01( ) CD4+ T cell nadir b Highest HIV RNA viral load a 85 (21-180) 4.90 ± (12-189) 5.11 ± Chronic Hepatitis C Chronic Hepatitis B 17 (11%) 9 (6%) 16 (8%) 21 (11%) 1.97( ) 0.72( ) At suppressive HAART initiation CD4+ T cell count b HIV RNA level a HAART regimen type NNRTI/ ≥ 2 NRTI All PI/ ≥ 2 NRTI Unboosted indinavir 126 (37-231) 4.68 ± (42%) 58 (55%) 27 (26%) 88 (19-222) 4.81 ± (48%) 87 (45%) 24 (13%) ( ) ( ) No. (%) with HAART-related side-effects 36 (34%)35 (18%)1.80( )<0.001 Weeks to viral suppression b 12 (6-23)16 (8-28)-0.04 One year CD4+ T cell gain b 99 (50-133)269 ( )-<0.001 Table 1. Characteristics of immune discordant vs. concordant responders. a Mean ±standard error of mean, b median (interquartile range), ARV = antiretroviral, NNRTI = non-nucleoside reverse transcriptase inhibitor, NRTI = nucleoside reverse transcriptase inhibitor, PI = protease inhibitor. RESULTS Independent factors associated with immune discordance on multivariable analyses: Male gender. Lower pre-HAART HIV-RNA viral load. Any use of unboosted indinavir. Greater number of HAART-related side effects per person. Figure 1. Absolute CD4 + T cell counts after HAART initiation. Clinical OutcomesDiscordant (106)Concordant (192)OR (95% CI)P value Years of viral suppression on HAART a Highest CD4+ T cell count attained b 4.56 ± ( ) 4.51 ± ( ) <0.001 Death Remains in clinical care Lost to follow up 5 (5%) 75 (71%) 26 (25%) 9 (5%) 150 (78%) 33 (17%) 1.00( ) New opportunistic illness Type of opportunistic illness Years after viral suppression OI prophylaxis at 1 yr viral suppression at highest CD4+ T cell count 1 NHL 2 and 5 61 (58%) 37 (35%) 1 Kaposi’s sarcoma 8 73 (38%) 30 (16%) ( ) 2.90( ) - <0.001 Recurrent genital warts Recurrent shingles Recurrent genital herpes 5 (5%) 10 (9%) 0 1 (1%) 7 (4%) 6 (3%) 9.46( ) 2.75( ) 1.57( ) Table 2. Clinical outcomes during long-term follow up. a Mean ± standard error of mean, b Median and interquartile range. NHL = non-Hodgkin’s lymphoma, OI = opportunistic infection. Data at the time of FACS analysis (mean ± S.E.M.) Discordant (n=20) Concordant (n=25) P value Age Gender: Male Female Race: Caucasian/Hispanic African American 48.7 ± (85%) 3 (15%) 15 (75%) 5 (25%) 48.7 ± (76%) 6 (24%) 10 (40%) 15 (60%) CD4+ T cell count (cells/mm 3 ) % <200 cells/mm 3 % cells/mm 3 % ≥ 350 cells/mm ± ± <0.001 Years of viral suppression5.6 ± ± CD4+ T cells a CD45RO+ Naïve:memory CD38+HLADR ± ± ± ± ± ± CD8+ T cells a CD45RO+ Naïve:memory CD38+HLADR ± ± ± ± ± ± Table 3. Comparison of activation and memory T-cells between discordant vs. concordant immune responders. a Percentage of total events. CD38+HLADR+ = marker of activation, CD45RO+ = marker of memory cell. CONCLUSION We would like to acknowledge Bristol-Myers Squibb for the Virology Fellows Research Grant which enabled this study to be done. In patients with viral suppression for a mean of 6.3 years, discordant responders had significantly higher levels of memory CD4+ T cells (CD45RO+) with a reduced naïve:memory CD4+ ratio (p<0.05 for all). Levels of activated CD4+ T cells (CD38+HLADR+) were higher among those with immune discordance, although this did not reach statistical significance. Levels of memory and activated CD8+ T cells were similar between groups.