Comparison of Entropy vs. Bispectral Index Anesthetic Depth Monitoring during Isoflurane Anesthesia in Living Donor Liver Transplantation: Observational Study

Liver transplantation (LT) recipients are known to require less anesthetic agents. Providing minimally required anesthetics while avoiding awareness is especially important in LT recipients because it would help manage perioperative hemodynamic instability with less vasopressor and fast track recovery. This study aims to compare state entropy (SE) against bispectral index (BIS) during isoflurane anesthesia in LT. We adjusted anesthesia to BIS values 40 - 60, and compared it with concomitant SE values. BIS, SE values, and anesthetic requirements according to liver failure severity, etiology and LT stages were analyzed. For BIS-SE differences, SE value that is different from the concomitant BIS by more than 15 was defined as a significant disagreement. Mann Whitney, Kruskal Wallis test and a Poisson exact test were used for analysis. The BIS-SE pair sets of 2895 from 38 patients were analyzed. BIS, SE values and anesthetic requirements were significantly lower in MELD ≥ 20 (p < 0.001 in all) and in alcoholic etiology (p < 0.001 in all). For BIS-SE differences, 320 disagreement data pairs were seen at a rate of 1.33 times/hr (95% CI = [1.19, 1.48], p < 0.001). A significant disagreement was delineated in MELD score ≥ 20 (3.04 times/hr, CI = [2.64, 3.49], p < 0.001), alcoholic etiology (3.19 times/hr, [2.67, 3.78], p < 0.001) and postreperfusion stage (1.63 times/hr, [1.43, 1.85], p < 0.001). In these significant BIS-SE differences, 95.9% (307/320 disagreement data pairs) showed higher BIS than SE. In conclusion, in high MELD and alcoholic etiology, anesthetic requirements were significantly less, and BIS and SE showed great discrepancy with lower SE values. Therefore, when SE monitoring is used during LT, anesthesiologists may need to consider that in high MELD and alcoholic etiology, SE tends to show lower values than the concomitant BIS values that are within optimal anesthetic depth ranges.

PD-1 blockade-unresponsive human tumor-infiltrating CD8^(+)T cells are marked by loss of CD28 expression and rescued by IL-15

Blockade of programmed death-1(PD-1)reinvigorates exhausted CD8^(+)T cells,resulting in tumor regression in cancer patients.Recently,reinvigoration of exhausted CD8^(+)T cells following PD-1 blockade was shown to be CD28-dependent in mouse models.Herein,we examined the role of CD28 in anti-PD-1 antibody-induced human T cell reinvigoration using tumor-infiltrating CD8^(+)T cells(CD8^(+)TILs)obtained from non-small-cell lung cancer patients.Single-cell analysis demonstrated a distinct expression pattern of CD28 between mouse and human CD8^(+)TILs.Furthermore,we found that human CD28^(+)CD8^(+)but not CD28^(–)CD8^(+)TILs responded to PD-1 blockade irrespective of B7/CD28 blockade,indicating that CD28 costimulation in human CD8^(+)TILs is dispensable for PD-1 blockade-induced reinvigoration and that loss of CD28 expression serves as a marker of anti-PD-1 antibody-unresponsive CD8^(+)TILs.Transcriptionally and phenotypically,PD-1 blockade-unresponsive human CD28^(–)PD-1^(+)CD8^(+)TILs exhibited characteristics of terminally exhausted CD8^(+)T cells with low TCF1 expression.Notably,CD28^(–)PD-1^(+)CD8^(+)TILs had preserved machinery to respond to IL-15,and IL-15 treatment enhanced the proliferation of CD28^(–)PD-1^(+)CD8^(+)TILs as well as CD28^(+)PD-1^(+)CD8^(+)TILs.Taken together,these results show that loss of CD28 expression is a marker of PD-1 blockade-unresponsive human CD8^(+)TILs with a TCF1–signature and provide mechanistic insights into combining IL-15 with anti-PD-1 antibodies.