Immune recovery markers in a double blind clinical trial comparing dolutegravir and raltegravir based regimens as initial therapy (SPRING-2).

Background: Multiple T-cell marker recovery (MTMR: CD4+ T-cells >500 cel/mm3 plus CD4+% >29% plus CD4+/CD8+ ratio >1) has been proposed as the most complete level of immune reconstitution. In this study we quantified differences in the CD4+/CD8+ ratio, CD4+% recovery and MTMR after starting HIV-1 treatment with dolutegravir (DTG) vs. raltegravir (RAL) plus a NRTI backbone.

Methods: Exploratory post-hoc analysis of the SPRING-2 study, a randomized double-blind clinical trial comparing DTG and RAL as third agents in naive HIV-infected patients at 100 sites in Canada, USA, Australia, and Europe. Percentage differences and corresponding precision based on 95% confidence intervals (CI) and p-values were calculated for i) CD4+/CD8+ ratio normalization, ii) CD4+% normalization, and iii) the achievement of MTMR.

Results: A total of 822 participants were analyzed (411 in each group). No statistically significant differences in the proportion of patients who reached a CD4+/CD8+ ratio ≥0.5 & ≥1 at w48 & w96 were observed. At w96, the proportion of patients with a CD4+/CD8+ ratio ≥1 was similar (30.43% DTG vs. 29.57% RAL). No differences were observed in the mean increase in CD4+/CD8+ ratio from baseline at both w48 & w96. Similarly, no significant differences in the CD4+/CD8+>29% were observed at w96 (72.95% DTG vs 69.28% RAL). The proportion of patients attaining MTMR criteria was also similar in the DTG group and the RAL group at w48 (20.33% vs. 18.26%; difference 2.07 (95%CI (-3.67;7.81) P = 0.481 and w96 (28.70% vs. 27.13; difference 1.56 (95%CI -5.22;8.34) P = 0.652).

Conclusion: After comparing DTG and RAL, no differences on immune recovery markers were observed.