Andrew Hill, Liverpool University, UK

1. Is monitoring for CD4 counts still needed for the management of patients with long-term HIV RNA suppression? Andrew Hill, Liverpool University, UK

2. Background • CD4 counts show which asymptomatic patients should be started on antiretroviral treatment (<350 or <500 cells/µL in different guidelines) • People with low CD4 counts on ARV treatment need prophylaxis for opportunistic infections – higher risk of AIDS • HIV RNA is much more sensitive than CD4 count, as a measure of treatment failure. • HIV RNA also provides information on the risk of HIV transmission, drug resistance and poor adherence • If a patient has CD4 counts above 200 cells/µL and HIV RNA <50 copies/mL, what is the use of continued CD4 testing? • Can we monitor with HIV RNA alone during long-term antiretroviral treatment?

3. Will the CD4 counts always stay above 200 cells/uL, while the HIV RNA is suppressed? HIV RNA <50 copies/mL

4. Immuno-Virological discordance – Do we still need CD4 testing? HIV RNA <50 copies/mL

5. Methods • In the ARTEMIS trial, 689 antiretroviral treatment-naïve patients were randomised to tenofovir/emtricitabine plus either darunavir/ritonavir (DRV/r) 800/100 mg once daily (n=343) or lopinavir/ritonavir (LPV/r) (n=346). • HIV RNA was evaluated using the Roche Amplicor Ultrasensitive assay. • CD4 counts were measured at baseline and every 12-16 weeks to Week 192. • The number of patients with CD4 counts above 200 copies/mL and HIV RNA <50 copies/mL at Week 48 was assessed. • For these patients, we assessed whether CD4 counts fell below 200 cells/uL from Week 48 to Week 192 on two consecutive visits, while HIV RNA suppression was maintained.

6. ARTEMIS study design Screening phase (2–4 weeks) Treatment phase (192 weeks) DRV/r 800/100mg qd + TDF 300mg and FTC 200mg (n=343) • 689 ARV-naïve patients • Viral load >5,000 • No CD4 cell count entry LPV/r 400/100mg bid or 800/200mg qd* + TDF 300mg and FTC 200mg (n=346) • TDF = tenofovir; FTC = emtricitabine • *Dosing and switch dependent on local regulatory approval and patient/investigator preference

7. Baseline demographics and disease characteristics SD = standard deviation; HBV = hepatitis B virus; HCV = hepatitis C virus

8. ARTEMIS: responders and non-responders There were 520 / 689 patients with HIV RNA <50 copies/mL and CD4 counts above 200 cells/uL at Week 48 At Week 48 the response rate was 262/343 (76%) in the DRV/r arm and 258/346 (75%) in the LPV/r arm. 482/520 patients (93%) had follow up data on CD4 counts and HIV RNA for Weeks 49-192.

9. ARTEMIS: responders and non-responders ____________________________________________________________________________________ Baseline characteristic Responders Non-responders n=520 n=169 ____________________________________________________________________________________ Age, years (median, IQR) 34 (28-42) 34 (28-40) Sex (% male) 70% 68% Race (% Caucasian) 43% 41% Baseline CD4 count (median, IQR)247 (171-341) 135 (55-248) Log10 BL HIV RNA (median, IQR) 4.8 (4.4–5.2) 4.9 (4.6–5.4) Progression to AIDS before Week 48 5 (1.0%) 19 (11.2%) * ____________________________________________________________________________________ * p=0.001, Fisher’s exact test.

10. ARTEMIS: lowest CD4 counts from Week 49-192, for patients with HIV RNA <50 copies/mL at Week 48 (no HIV RNA elevations >400 during follow up) _________________________________________________________________________ CD4 count Lowest CD4 count on two consecutive visits, Week 49-192 At Week 48 <200 200<349 350-499 >=500 _________________________________________________________________________ 200-349 (n=137) 4 (3%) 95 (69%) 35 (26%) 3 (2%) 350-499 (n=174) 1 (0.6%) 15 (9%) 109 (62%) 49 (28%) >=500 (n=138) 0 0 21 (15%) 117 (85%) _________________________________________________________________________

11. ARTEMIS: lowest CD4 counts from Week 49-192, for patients with HIV RNA <50 copies/mL at Week 48 (with HIV RNA elevations >400 during follow up) _________________________________________________________________________ CD4 count Lowest CD4 count on two consecutive visits, Week 49-192 At Week 48 <200 200<349 350-499 >=500 _________________________________________________________________________ 200-349 (n=17) 2 (12%) 13 (77%) 1 (6%) 1 (6%) 350-499 (n=10) 0 1 (10%) 8 (80%) 1 (10%) >=500 (n=6) 0 2 (33%) 2 (33%) 2 (33%) _________________________________________________________________________

12. ARTEMIS: AIDS defining events during follow-up Among the 482 responder patients with data to Week 192, 6 (1.2%) progressed to AIDS between Weeks 49-192. Only 1 of these patients had a confirmed reduction in CD4 count below 200 cells/uL at the time of AIDS diagnosis (lymphoma). This patient had CD4 counts above 200 cells/uL in the visit before lymphoma was diagnosed. The other 5 patients had CD4 counts above 200 cells/uL at the time of diagnosis of new AIDS events (Pulmonary TB and oesophageal candidiasis).

13. HIV RNA <50 copies/mL

14. Limitations of the ARTEMIS trial analysis Patients can take longer than 48 weeks to show rises in CD4 count above 200 cells/uL by Week 48 There is limited statistical power to evaluate progression to AIDS Patients could discontinue the trial after virological failure – limited follow up on second-line treatments

15. US Veteran Affairs Study 1820 patients in the Washington Veteran Affairs cohort study, on antiretroviral treatment (1998-2011) Patients with HIV RNA <200 copies/mL and CD4 counts >=300 cells/uL had a 97.1% probability of maintaining durable CD4 >=200 cells/uL for four years. When non-HIV causes of lymphopenia were excluded, the probability rose to 99.2%. The results supported less frequent monitoring of CD4 during viral suppression Gale et al. CID 2013 online

16. MONET trial - lowest CD4 counts during 144 week follow-up, in the MONET Trial (HIV RNA <50 c/mL at baseline) Stephan et al. JAIDS 2012, 61: e73-e75

17. MONET: Patient with short-term CD4 decline <200 From baseline to Week 144, HIV RNA was <50 copies/mL. No change in treatment. CD4 percentage was in the range of 22-27% throughout the trial, except for a single result of 17% when the absolute CD4 count was also low. CD4 count cells/uL Weeks on treatment (HIV RNA <50 copies/mL) Stephan et al. JAIDS 2012, 61: e73-e75

18. Royal Free cohort, London Follow-up of 166 patients on antiretroviral therapy with HIV RNA <50 copies/mL and CD4 counts above 500 cells/µL Only five of the 166 patients (3%) showed a decline in CD4 count <350 cells/µL during 47 weeks of follow up. All were isolated reductions: _________________________________________________________________________ Patient Baseline Low visit Follow up visit _________________________________________________________________________ 1 532 262 374 2 740 330 705 3 650 331 792 4 560 347 392 5 642 349 404 _________________________________________________________________________ Phillips et al. AIDS 2002, 16: 1073-1075

19. German ClinServ Cohort Risk of AIDS measured for patients with HIV RNA <50 copies/mL but CD4 count still below 200 cells/µL while on antiretroviral treatment. 5038 patient-years of follow up. The risk of AIDS events was very low for patients with at least two years of HIV RNA suppression, even if the CD4 count was below 200 cells/µL Zoufaly et al. J Infect Dis 2011, 203: 364-371

20. Before ART Antiretroviral Treatment CD4 CD4 + RNA HIV RNA only? HIV RNA CD4 COUNT

21. Before ART Antiretroviral Treatment CD4 CD4 + RNA HIV RNA only HIV RNA CD4 COUNT

22. Conclusions In the ARTEMIS and MONET trials, there was no added benefit to testing for CD4 counts for patients whose CD4 counts were above 200 cells/µL and who had full HIV RNA suppression after 48 weeks of first-line treatment. Continued full HIV RNA suppression could therefore be used as an alternative surrogate marker for sustained elevations in CD4 count.

23. Questions still to be answered: If HIV RNA rebounds on treatment, when should we re-start CD4 counting? HIV RNA >10,000? (PLATO cohort). Does this strategy of stopping CD4 testing need to be evaluated in larger cohort studies?