A virtual memory CD8+ T cell-originated subset causes alopecia areata through innate-like cytotoxicity.

Virtual memory T (TVM) cells are a T cell subtype with a memory phenotype but no prior exposure to foreign antigen. Although TVM cells have antiviral and antibacterial functions, whether these cells can be pathogenic effectors of inflammatory disease is unclear. Here we identified a TVM cell-originated CD44super-high(s-hi)CD49dlo CD8+ T cell subset with features of tissue residency. These cells are transcriptionally, phenotypically and functionally distinct from conventional CD8+ TVM cells and can cause alopecia areata. Mechanistically, CD44s-hiCD49dlo CD8+ T cells could be induced from conventional TVM cells by interleukin (IL)-12, IL-15 and IL-18 stimulation. Pathogenic activity of CD44s-hiCD49dlo CD8+ T cells was mediated by NKG2D-dependent innate-like cytotoxicity, which was further augmented by IL-15 stimulation and triggered disease onset. Collectively, these data suggest an immunological mechanism through which TVM cells can cause chronic inflammatory disease by innate-like cytotoxicity.

PD-1-Expressing SARS-CoV-2-Specific CD8+ T Cells Are Not Exhausted, but Functional in Patients with COVID-19.

Memory T cell responses have been demonstrated in COVID-19 convalescents, but ex vivo phenotypes of SARS-CoV-2-specific T cells have been unclear. We detected SARS-CoV-2-specific CD8+ T cells by MHC class I multimer staining and examined their phenotypes and functions in acute and convalescent COVID-19. Multimer+ cells exhibited early differentiated effector-memory phenotypes in the early convalescent phase. The frequency of stem-like memory cells was increased among multimer+ cells in the late convalescent phase. Cytokine secretion assays combined with MHC class I multimer staining revealed that the proportion of interferon-γ (IFN-γ)-producing cells was significantly lower among SARS-CoV-2-specific CD8+ T cells than those specific to influenza A virus. Importantly, the proportion of IFN-γ-producing cells was higher in PD-1+ cells than PD-1- cells among multimer+ cells, indicating that PD-1-expressing, SARS-CoV-2-specific CD8+ T cells are not exhausted, but functional. Our current findings provide information for understanding of SARS-CoV-2-specific CD8+ T cells elicited by infection or vaccination.

Innate-like Cytotoxic Function of Bystander-Activated CD8+ T Cells Is Associated with Liver Injury in Acute Hepatitis A.

Acute hepatitis A (AHA) involves severe CD8+ T cell-mediated liver injury. Here we showed during AHA, CD8+ T cells specific to unrelated viruses became activated. Hepatitis A virus (HAV)-infected cells produced IL-15 that induced T cell receptor (TCR)-independent activation of memory CD8+ T cells. TCR-independent activation of non-HAV-specific CD8+ T cells were detected in patients, as indicated by NKG2D upregulation, a marker of TCR-independent T cell activation by IL-15. CD8+ T cells derived from AHA patients exerted innate-like cytotoxicity triggered by activating receptors NKG2D and NKp30 without TCR engagement. We demonstrated that the severity of liver injury in AHA patients correlated with the activation of HAV-unrelated virus-specific CD8+ T cells and the innate-like cytolytic activity of CD8+ T cells, but not the activation of HAV-specific T cells. Thus, host injury in AHA is associated with innate-like cytotoxicity of bystander-activated CD8+ T cells, a result with implications for acute viral diseases.

Next-generation MRI scanner designed for ultra-high-resolution human brain imaging at 7 Tesla.

To increase granularity in human neuroimaging science, we designed and built a next-generation 7 Tesla magnetic resonance imaging scanner to reach ultra-high resolution by implementing several advances in hardware. To improve spatial encoding and increase the image signal-to-noise ratio, we developed a head-only asymmetric gradient coil (200 mT m-1, 900 T m-1s-1) with an additional third layer of windings. We integrated a 128-channel receiver system with 64- and 96-channel receiver coil arrays to boost signal in the cerebral cortex while reducing g-factor noise to enable higher accelerations. A 16-channel transmit system reduced power deposition and improved image uniformity. The scanner routinely performs functional imaging studies at 0.35-0.45 mm isotropic spatial resolution to reveal cortical layer functional activity, achieves high angular resolution in diffusion imaging and reduces acquisition time for both functional and structural imaging.

Distinctive Dynamics and Functions of the CD4+CD25+FOXP3+ Regulatory T Cell Population in Patients with Severe and Mild COVID-19.

Although CD4+CD25+FOXP3+ regulatory T (TREG) cells have been studied in patients with COVID-19, changes in the TREG cell population have not been longitudinally examined during the course of COVID-19. In this study, we longitudinally investigated the quantitative and qualitative changes in the TREG cell population in patients with COVID-19. We found that the frequencies of total TREG cells and CD45RA-FOXP3hi activated TREG cells were significantly increased 15-28 d postsymptom onset in severe patients, but not in mild patients. TREG cells from severe patients exhibited not only increased proliferation but also enhanced apoptosis, suggesting functional derangement of the TREG cell population during severe COVID-19. The suppressive functions of the TREG cell population did not differ between patients with severe versus mild COVID-19. The frequency of TREG cells inversely correlated with SARS-CoV-2-specific cytokine production by CD4+ T cells and their polyfunctionality in patients with mild disease, suggesting that TREG cells are major regulators of virus-specific CD4+ T cell responses during mild COVID-19. However, such correlations were not observed in patients with severe disease. Thus, in this study, we describe distinctive changes in the TREG cell population in patients with severe and mild COVID-19. Our study provides a deep understanding of host immune responses upon SARS-CoV-2 infection in regard to TREG cells.

Epigenetic scars in regulatory T cells are retained after successful treatment of chronic hepatitis C with direct-acting antivirals.

BACKGROUND & AIMS: Chronic hepatitis C virus (HCV) infection results in abnormal immunological alterations, which are not fully normalized after viral elimination by direct-acting antiviral (DAA) treatment. Here we longitudinally examined phenotypic, transcriptomic, and epigenetic alterations in peripheral blood regulatory T (TREG) cells from patients with chronic HCV infection according to DAA treatment. METHODS: Patients with chronic genotype 1b HCV infection who achieved sustained virologic response (SVR) by DAA treatment and age-matched healthy donors were recruited. Phenotypic characteristics of TREG cells were investigated through flow cytometry analysis. Moreover, transcriptomic and epigenetic landscape of TREG cells were analyzed using RNA-seq and ATAC-seq analysis. RESULTS: The TREG cell population-especially the activated TREG cell subpopulation-was expanded in peripheral blood during chronic HCV infection, and this expansion was sustained even after viral clearance. RNA-seq analysis revealed that viral clearance did not abrogate the inflammatory features of these TREG cells, such as TREG activation and TNF signal. Moreover, ATAC-seq analysis showed inflammatory imprinting in the epigenetic landscape of TREG cells from patients, which remained after treatment. These findings were further confirmed by intracellular cytokine staining, demonstrating that TREG cells exhibited inflammatory features and TNF production in chronic HCV infection that were maintained after viral clearance. CONCLUSIONS: Overall, our results showed that during chronic HCV infection, the expanded TREG cell population acquired inflammatory features at phenotypic, transcriptomic, and epigenetic levels, which were maintained even after successful viral elimination by DAA treatment. Further studies are warranted to examine the clinical significance of sustained inflammatory features in the TREG cell population after recovery from chronic HCV infection. IMPACT AND IMPLICATIONS: During chronic HCV infection, several immune components are altered both quantitatively and qualitatively. The recent introduction of DAAs led to a high cure rate of chronic HCV infection. Nevertheless, we have demonstrated that inflammatory features of TREG cells are maintained at phenotypic, transcriptomic, and epigenetic levels even after successful DAA treatment. Further in-depth studies are required to investigate the long-term clinical outcomes of patients who have recovered from chronic HCV infection.

IFITM3 Is Upregulated Characteristically in IL-15-Mediated Bystander-Activated CD8+ T Cells during Influenza Infection.

In bystander activation, pre-existing memory CD8+ T cells unrelated to the infecting microbes are activated by cytokines without cognate Ags. The detailed mechanisms and unique gene signature of bystander activation remain to be elucidated. In this study, we investigated bystander activation of OT-1 memory cells in a mouse model of influenza infection. We found that OT-1 memory cells are activated with upregulation of granzyme B and IFN-γ, during PR8 (A/Puerto Rico/8/1934) infection, and IL-15 is a critical cytokine for bystander activation. In transcriptomic analysis, the IFN-induced gene signature was upregulated in bystander-activated OT-1 memory cells during PR8 infection but not in the presence of TCR stimulation. Among the IFN-induced genes, upregulation of IFN-induced transmembrane protein 3 (IFITM3) distinguished bystander-activated OT-1 memory cells from TCR-activated OT-1 memory cells. Therefore, we reveal that bystander-activated memory CD8+ T cells have a unique transcriptomic feature compared with TCR-activated memory CD8+ T cells. In particular, IFITM3 upregulation can be used as a marker of bystander-activated memory CD8+ T cells at early infection.

CD5 Suppresses IL-15-Induced Proliferation of Human Memory CD8+ T Cells by Inhibiting mTOR Pathways.

IL-15 induces the proliferation of memory CD8+ T cells as well as NK cells. The expression of CD5 inversely correlates with the IL-15 responsiveness of human memory CD8+ T cells. However, whether CD5 directly regulates IL-15-induced proliferation of human memory CD8+ T cells is unknown. In the current study, we demonstrate that human memory CD8+ T cells in advanced stages of differentiation respond to IL-15 better than human memory CD8+ T cells in stages of less differentiation. We also found that the expression level of CD5 is the best correlate for IL-15 hyporesponsiveness among human memory CD8+ T cells. Importantly, we found that IL-15-induced proliferation of human memory CD8+ T cells is significantly enhanced by blocking CD5 with Abs or knocking down CD5 expression using small interfering RNA, indicating that CD5 directly suppresses the IL-15-induced proliferation of human memory CD8+ T cells. We also found that CD5 inhibits activation of the mTOR pathway, which is required for IL-15-induced proliferation of human memory CD8+ T cells. Taken together, the results indicate that CD5 is not just a correlative marker for IL-15 hyporesponsiveness, but it also directly suppresses IL-15-induced proliferation of human memory CD8+ T cells by inhibiting mTOR pathways.

Frequency of peripheral PD-1+regulatory T cells is associated with treatment responses to PARP inhibitor maintenance in patients with epithelial ovarian cancer.

BACKGROUND: Poly (adenosine diphosphate [ADP]-ribose) polymerase inhibitors (PARPis) are becoming the standard of care for epithelial ovarian cancer (EOC). Recently, clinical trials of triple maintenance therapy (PARPi+anti-angiogenic agent+anti-PD-1/L1) are actively ongoing. Here, we investigated the immunological effects of PARPi or triple maintenance therapy on T cells and their impact on clinical responses. METHODS: We collected serial blood from EOC patients receiving PARPi therapy (cohort 1: PARPi, n = 49; cohort 2: olaparib+bevacizumab+pembrolizumab, n = 31). Peripheral T cells were analyzed using flow cytometry and compared according to the PARPi response. Progression-free survival (PFS) was assessed according to prognostic biomarkers identified in a comparative analysis. RESULTS: Regulatory T cells (Tregs) were suppressed by PARPi therapy, whereas PD-1 was not significantly changed. Short PFS group exhibited a higher percentage of baseline PD-1+Tregs than long PFS group, and the patients with high percentage of PD-1+Tregs before treatment showed poor PFS in cohort 1. However, the expression of PD-1 on Tregs significantly decreased after receiving triple maintenance therapy, and the reduction in PD-1+Tregs was associated with superior PFS in cohort 2 (P = 0.0078). CONCLUSION: PARPi suppresses Tregs, but does not affect PD-1 expression. Adding anti-PD-1 to PARPi decreases PD-1+Tregs, which have negative prognostic value for PARPi monotherapy.

Dynamic changes in peripheral blood monocytes early after anti-PD-1 therapy predict clinical outcomes in hepatocellular carcinoma.

Immune checkpoint inhibitors are effective for advanced hepatocellular carcinoma (HCC), but there remains a need for peripheral blood biomarkers to predict the clinical response. Here, we analyzed the peripheral blood of 45 patients with advanced HCC who underwent nivolumab. During treatment, frequency of classical monocytes (CD14+CD16-) was increased on day 7, and the fold increase in the frequency on day 7 over day 0 (cMonocyteD7/D0) was significantly higher in patients with durable clinical benefit (DCB) than in patients with non-DCB (NDB). When we analyzed transcriptomes of classical monocytes, CD274, gene encoding PD-L1, was upregulated in NDB patients compared to DCB patients at day 7. Notably, gene signature of suppressive tumor-associated macrophages, or IL4l1+PD-L1+IDO1+ macrophages, was enriched after treatment in NDB patients, but not in DCB patients. Accordingly, the fold increase in the frequency of PD-L1+ classical monocytes at day 7 over day 0 (cMonocyte-PDL1D7/D0) was higher in NDB patients than DCB patients. The combined biomarker cMonocyteD7/D0/cMonocyte-PDL1D7/D0 was termed the "monocyte index", which was significantly higher in DCB patients than NDB patients. Moreover, the monocyte index was an independent prognostic factor for survival. Overall, our results suggest that early changes of circulating classical monocytes, represented as a monocyte index, could predict clinical outcomes of advanced HCC patients undergoing anti-PD-1 therapy.

3D CEST MRI with an unevenly segmented RF irradiation scheme: A feasibility study in brain tumor imaging.

PURPOSE: To integrate 3D CEST EPI with an unevenly segmented RF irradiation module and preliminarily demonstrate it in the clinical setting. METHODS: A CEST MRI with unevenly segmented RF saturation was implemented, including a long primary RF saturation to induce the steady-state CEST effect, maintained with repetitive short secondary RF irradiation between readouts. This configuration reduces relaxation-induced blur artifacts during acquisition, allowing fast 3D spatial coverage. Numerical simulations were performed to select parameters such as flip angle (FA), short RF saturation duration (Ts2), and the number of readout segments. The sequence was validated experimentally with data from a phantom, healthy volunteers, and a brain tumor patient. RESULTS: Based on the numerical simulation and l-carnosine gel phantom experiment, FA, Ts2, and the number of segments were set to 20°, 0.3 s, and the range from 4 to 8, respectively. The proposed method minimized signal modulation in the human brain images in the kz direction during the acquisition and provided the blur artifacts-free CEST contrast over the whole volume. Additionally, the CEST contrast in the tumor tissue region is higher than in the contralateral normal tissue region. CONCLUSIONS: It is feasible to implement a highly accelerated 3D EPI CEST imaging with unevenly segmented RF irradiation.

Immune responses to HCV and other hepatitis viruses.

Five human hepatitis viruses cause most of the acute and chronic liver disease worldwide. Over the past 25 years, hepatitis C virus (HCV) in particular has received much interest because of its ability to persist in most immunocompetent adults and because of the lack of a protective vaccine. Here we examine innate and adaptive immune responses to HCV infection. Although HCV activates an innate immune response, it employs an elaborate set of mechanisms to evade interferon (IFN)-based antiviral immunity. By comparing innate and adaptive immune responses to HCV with those to hepatitis A and B viruses, we suggest that prolonged innate immune activation by HCV impairs the development of successful adaptive immune responses. Comparative immunology provides insights into the maintenance of immune protection. We conclude by discussing prospects for an HCV vaccine and future research needs for the hepatitis viruses.

IL-17A-producing sinonasal MAIT cells in patients with chronic rhinosinusitis with nasal polyps.

BACKGROUND: Diverse immune cells contribute to the pathogenesis of chronic rhinosinusitis (CRS), an inflammatory disease of the nasal cavity and paranasal sinuses. However, whether mucosal-associated invariant T (MAIT) cells are present in human sinonasal tissues remains unclear. Furthermore, the characteristics of sinonasal MAIT cells have not been studied in patients with CRS. OBJECTIVE: We investigated the phenotype, function, and clinical implications of MAIT cells in patients with CRS. METHODS: Peripheral blood and sinonasal tissue were obtained from patients with CRS with (CRSwNP) or without nasal polyps (CRSsNP) and healthy controls. MAIT cells were analyzed by flow cytometry. RESULTS: We found that MAIT cells are present in human sinonasal tissues from healthy controls and patients with CRS. The sinonasal MAIT cell population, but not peripheral blood MAIT cells, from patients with CRSsNP, noneosinophilic CRSwNP (NE-NP), or eosinophilic CRSwNP (E-NP) had a significantly higher frequency of activated cells marked by CD38 expression. In functional analysis, the sinonasal MAIT cell population from NE-NP and E-NP had a significantly higher frequency of IL-17A+ cells but lower frequency of IFN-γ+ or TNF+ cells than control sinonasal tissues. Furthermore, CD38 expression and IL-17A production by sinonasal MAIT cells significantly correlated with disease extent evaluated by the Lund-Mackay computed tomography score in patients with E-NP. CONCLUSIONS: Sinonasal MAIT cells exhibit an activated phenotype and produce higher levels of IL-17A in patients with CRSwNP. These alterations are associated with the extent of disease in patients with E-NP.

Impaired antibacterial response of liver sinusoidal Vγ9+Vδ2+ T cells in patients with chronic liver disease.

OBJECTIVE: The liver acts as a frontline barrier against diverse gut-derived pathogens, and the sinusoid is the primary site of liver immune surveillance. However, little is known about liver sinusoidal immune cells in the context of chronic liver disease (CLD). Here, we investigated the antibacterial capacity of liver sinusoidal γδ T cells in patients with various CLDs. DESIGN: We analysed the frequency, phenotype and functions of human liver sinusoidal γδ T cells from healthy donors and recipients with CLD, including HBV-related CLD (liver cirrhosis (LC) and/or hepatocellular carcinoma (HCC)), alcoholic LC and LC or HCC of other aetiologies, by flow cytometry and RNA-sequencing using liver perfusates obtained during living donor liver transplantation. We also measured the plasma levels of D-lactate and bacterial endotoxin to evaluate bacterial translocation. RESULTS: The frequency of liver sinusoidal Vγ9+Vδ2+ T cells was reduced in patients with CLD. Immunophenotypic and transcriptomic analyses revealed that liver sinusoidal Vγ9+Vδ2+ T cells from patients with CLD were persistently activated and pro-apoptotic. In addition, liver sinusoidal Vγ9+Vδ2+ T cells from patients with CLD showed significantly decreased interferon (IFN)-γ production following stimulation with bacterial metabolites and Escherichia coli. The antibacterial IFN-γ response of liver sinusoidal Vγ9+Vδ2+ T cells significantly correlated with liver function, and inversely correlated with the plasma level of D-lactate in patients with CLD. Repetitive in vitro stimulation with E. coli induced activation, apoptosis and functional impairment of liver sinusoidal Vγ9+Vδ2+ T cells. CONCLUSION: Liver sinusoidal Vγ9+Vδ2+ T cells are functionally impaired in patients with CLD. Bacterial translocation and decreasing liver functions are associated with functional impairment of liver sinusoidal Vγ9+Vδ2+ T cells.

Identification of a distinct NK-like hepatic T-cell population activated by NKG2C in a TCR-independent manner.

BACKGROUND & AIMS: The liver provides a unique niche of lymphocytes enriched with a large proportion of innate-like T cells. However, the heterogeneity and functional characteristics of the hepatic T-cell population remain to be fully elucidated. METHODS: We obtained liver sinusoidal mononuclear cells from the liver perfusate of healthy donors and recipients with HBV-associated chronic liver disease (CLD) during liver transplantation. We performed a CITE-seq analysis of liver sinusoidal CD45+ cells in combination with T cell receptor (TCR)-seq and flow cytometry to examine the phenotypes and functions of liver sinusoidal CD8+ T cells. RESULTS: We identified a distinct CD56hiCD161-CD8+ T-cell population characterized by natural killer (NK)-related gene expression and a uniquely restricted TCR repertoire. The frequency of these cells among the liver sinusoidal CD8+ T-cell population was significantly increased in patients with HBV-associated CLD. Although CD56hiCD161-CD8+ T cells exhibit weak responsiveness to TCR stimulation, CD56hiCD161-CD8+ T cells highly expressed various NK receptors, including CD94, killer immunoglobulin-like receptors, and NKG2C, and exerted NKG2C-mediated NK-like effector functions even in the absence of TCR stimulation. In addition, CD56hiCD161-CD8+ T cells highly respond to innate cytokines, such as IL-12/18 and IL-15, in the absence of TCR stimulation. We validated the results from liver sinusoidal CD8+ T cells using intrahepatic CD8+ T cells obtained from liver tissues. CONCLUSIONS: In summary, the current study found a distinct CD56hiCD161-CD8+ T-cell population characterized by NK-like activation via TCR-independent NKG2C ligation. Further studies are required to elucidate the roles of liver sinusoidal CD56hiCD161-CD8+ T cells in immune responses to microbial pathogens or liver immunopathology. LAY SUMMARY: The role of different immune cell populations in the liver is becoming an area of increasing interest. Herein, we identified a distinct T-cell population that had features similar to those of natural killer (NK) cells - a type of innate immune cell. This distinct population was expanded in the livers of patients with chronic liver disease and could thus have pathogenic relevance.

Tumour-infiltrating bystander CD8+ T cells activated by IL-15 contribute to tumour control in non-small cell lung cancer.

BACKGROUND: Tumour-unrelated, virus-specific bystander CD8+ T cells were recently shown to be abundant among tumour-infiltrating lymphocytes (TILs). However, their roles in tumour immunity have not been elucidated yet. METHODS: We studied the characteristics of bystander CD8+ TILs from non-small cell lung cancer (NSCLC) tissues (N=66) and their activation by interleukin (IL)-15 to repurpose them for tumour immunotherapy. RESULTS: We show that bystander CD8+ TILs specific to various viruses are present in human NSCLC tissues. We stimulated CD8+ TILs ex vivo using IL-15 without cognate antigens and found that IL-15 treatment upregulated NKG2D expression on CD8+ TILs, resulting in NKG2D-dependent production of interferon (IFN)-γ (p=0.0006). Finally, we tested whether IL-15 treatment can control tumour growth in a murine NSCLC model with or without a history of murine cytomegalovirus (MCMV) infection. IL-15 treatment reduced the number of tumour nodules in the lung only in mice with MCMV infection (p=0.0037). We confirmed that MCMV-specific bystander CD8+ TILs produced interferon (IFN)-γ after IL-15 treatment, and that IL-15 treatment in MCMV-infected mice upregulated tumour necrosis factor-α and IFN-γ responsive genes in tumour microenvironment. CONCLUSION: Thus, the study demonstrates that bystander CD8+ TILs can be repurposed by IL-15 for tumour immunotherapy.

Abnormality in the NK-cell population is prolonged in severe COVID-19 patients.

BACKGROUND: Our understanding of adaptive immune responses in patients with coronavirus disease 2019 (COVID-19) is rapidly evolving, but information on the innate immune responses by natural killer (NK) cells is still insufficient. OBJECTIVE: We aimed to examine the phenotypic and functional status of NK cells and their changes during the course of mild and severe COVID-19. METHODS: We performed RNA sequencing and flow cytometric analysis of NK cells from patients with mild and severe COVID-19 at multiple time points in the course of the disease using cryopreserved PBMCs. RESULTS: In RNA-sequencing analysis, the NK cells exhibited distinctive features compared with healthy donors, with significant enrichment of proinflammatory cytokine-mediated signaling pathways. Intriguingly, we found that the unconventional CD56dimCD16neg NK-cell population expanded in cryopreserved PBMCs from patients with COVID-19 regardless of disease severity, accompanied by decreased NK-cell cytotoxicity. The NK-cell population was rapidly normalized alongside the disappearance of unconventional CD56dimCD16neg NK cells and the recovery of NK-cell cytotoxicity in patients with mild COVID-19, but this occurred slowly in patients with severe COVID-19. CONCLUSIONS: The current longitudinal study provides a deep understanding of the NK-cell biology in COVID-19.

Longitudinal Assessment of Antisevere Acute Respiratory Syndrome Coronavirus 2 Immune Responses for Six Months Based on the Clinical Severity of Coronavirus Disease 2019.

BACKGROUND: There is insufficient data on the longevity of immunity acquired after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. METHODS: We aimed to evaluate the duration of SARS-CoV-2-specific humoral and cellular immunity according to the clinical severity of coronavirus disease 2019 (COVID-19). The study population comprised asymptomatic (n = 14), symptomatic/nonpneumonic (n = 42), and pneumonic (n = 41) patients. RESULTS: The anti-SARS-CoV-2 immunoglobulin class G and neutralizing antibody (NAb) titers lasted until 6 months after diagnosis, with positivity rates of 66.7% and 86.9%, respectively. Older age, prolonged viral shedding, and accompanying pneumonia were more frequently found in patients with sustained humoral immunity. Severe acute respiratory syndrome coronavirus 2-specific T-cell response was strongly observed in pneumonic patients and prominent in individuals with sustained humoral immunity. CONCLUSIONS: In conclusion, most (>85%) patients carry NAb until 6 months after diagnosis of SARS-CoV-2 infection, providing insights for establishing vaccination strategies against COVID-19.

Hyperprogressive disease during PD-1 blockade in patients with advanced hepatocellular carcinoma.

BACKGROUND & AIMS: Programmed cell death-1 (PD-1) inhibitor treatment can cause hyperprogressive disease (HPD), but the incidence, outcome, and predictive factors of HPD are unknown in patients with hepatocellular carcinoma (HCC). Herein, we assessed the existence and factors predictive of HPD in patients with advanced HCC treated with nivolumab. METHODS: We enrolled 189 patients with advanced HCC treated with nivolumab. Occurrence of HPD was investigated using tumour growth dynamics based on tumour growth kinetics (TGK) and tumour growth rate (TGR) before and after treatment, or time to treatment failure. We additionally analysed patients treated with regorafenib (n = 95) or best supportive care (BSC)/placebo (n = 103) after progression on sorafenib to compare tumour growth dynamics. RESULTS: Flare-up of tumour growth was observed in a fraction of patients upon PD-1 blockade, indicating the occurrence of HPD. Based on distinct patterns of disease progression exclusively observed in the nivolumab-treated cohort, but not in the regorafenib- or BSC/placebo-treated cohorts, 4-fold increases in TGK and TGR ratios as well as a 40% increase in TGR were the cut-off values used to define HPD; 12.7% of the patients (24/189) treated with nivolumab met all these criteria. Patients with HPD had worse progression-free survival (hazard ratio [HR] 2.194; 95% CI 1.214-3.964) and overall survival (HR 2.238; 95% CI 1.233-4.062) compared to patients with progressive disease without HPD. More than 90% of patients with HPD missed the opportunity for subsequent treatment because of rapid clinical deterioration. An elevated neutrophil-to-lymphocyte ratio (>4.125) was associated with HPD and an inferior survival rate. CONCLUSIONS: HPD occurs in a fraction of patients with HCC who receive PD-1 inhibitor treatment. Analyses of the baseline immune profile and on-treatment tumour growth dynamics could enable optimal patient selection and earlier identification of HPD. LAY SUMMARY: Hyperprogressive disease is an unexpected response pattern observed in patients treated with an immune checkpoint inhibitor. This study revealed that hyperprogressive disease occurs in a fraction of patients with advanced hepatocellular carcinoma treated with an anti-PD-1 antibody, providing evidence to encourage careful monitoring of patients to prevent clinical deterioration induced by PD-1 blockade.