Extended Data Fig. 4: T cell subsets during ATI.

Immunophenotyping at baseline and during a viremic time point indicating changes in A) T follicular helper-like (TFH) cells, B) peripheral CXCR5 + CD8 + T cells, and C) CCR6 + CD4 + T cells. Crosses indicate the 5 of the 6 participants in the stage II budigalimab 10-mg Q2W×4 arm who experienced a delayed viral rebound with a low viral load and/or viral load resuppression after rebound. P-values were assessed using Wilcoxon matched-pairs signed rank test. Viral load in the post-baseline samples ranged between undetectable and 81,950 copies/mL in the 10-mg Q4W×2 arm, between 405 and 54,400 copies/mL in the PBO arm, and between 22 and 96,400 copies/mL in the 10-mg Q2W×4 arm. Nearly complete PD-1 receptor saturation with budigalimab ( > 95 %) was observed on CD4+ and CD8 + T cells at the post-baseline sample in both 10-mg treatment arms (data not shown). Non-naive CD4+ and CD8 + T cell populations were identified using markers CD45RO, CD28, and CCR7, wherein naive cells were identified as CD28 + CD45RO − CCR7+ cells and a Boolean filter was utilized to distinguish non-naive cells. Although, Th1 is defined as CCR4 − CCR6 − CXCR3+ cells, Th2 as CCR4 + CCR6 − CXCR3− cells, Th17 as CCR6 + CD161+ or CCR6+ cells, and TFH-like as CXCR5+ cells, CXCR3+ cells could not be gated appropriately. Hence, within CD4 + T cell non-naive cells, cells were gated with CCR4 and CCR6 markers. At baseline, 71% ± 14% of the CD8 + /non-naive/CXCR5+ cells expressed PD-1 and 42% ± 8% of TFH-like cells expressed PD-1 (data not shown). No changes in CD4 + /non-naive/CCR4+ cells were apparent at post-baseline time points (data not shown). ATI; analytical treatment interruption; PBO, placebo; Q4W, every 4 weeks.