T-cell receptor architecture and clonal tiding provide insight into the transformation trajectory of peripheral T-cell lymphomas.

While T cell lymphomas are classified as mature neoplasms, emerging evidence indicates that malignant transformation may occur at an earlier stage of T cell maturation. In this study, we determined clonal architectures in a broad range of T cell lymphomas. Our multidimensional profiling indicates that a large part of these lymphomas in fact emerge from an immature lymphoid T cell precursor at a maturation stage prior to V(D)J rearrangement that undergoes branching evolution. Consequently, at single cell resolution we observed considerable clonal tiding under selective therapeutic pressure. T cell receptor next-generation sequencing suggested a highly biased usage of TRBV20-1 gene segments as part of multiple antigen receptor rearrangements per patient. The predominance of TRBV20-1 was found across all major T cell lymphoma subtypes analyzed. This suggested that this particular V gene - independently of complementarity-determining region 3 (CDR3) configuration - may represent a driver of malignant transformation. Together, our data indicate that T cell lymphomas derive from immature lymphoid precursors and display considerable intratumoral heterogeneity that may provide the basis for relapse and resistance in these hard-to-treat cancers.

A20 haploinsufficiency disturbs immune homeostasis and drives the transformation of lymphocytes with permissive antigen receptors.

Genetic TNFAIP3 (A20) inactivation is a classical somatic lymphoma lesion and the genomic trait in haploinsufficiency of A20 (HA20). In a cohort of 34 patients with HA20, we show that heterozygous TNFAIP3 loss skews immune repertoires toward lymphocytes with classical self-reactive antigen receptors typically found in B and T cell lymphomas. This skewing was mediated by a feed-forward tumor necrosis factor (TNF)/A20/nuclear factor κB (NF-κB) loop that shaped pre-lymphoma transcriptome signatures in clonally expanded B (CD81, BACH2, and NEAT1) or T (GATA3, TOX, and PDCD1) cells. The skewing was reversed by anti-TNF treatment but could also progress to overt lymphoma. Analysis of conditional TNFAIP3 knock-out mice reproduced the wiring of the TNF/A20/NF-κB signaling axis with permissive antigen receptors and suggested a distinct regulation in B and T cells. Together, patients with the genetic disorder HA20 provide an exceptional window into A20/TNF/NF-κB-mediated control of immune homeostasis and early steps of lymphomagenesis that remain clinically unrecognized.

B cells expressing mutated IGHV1-69-encoded antigen receptors related to virus neutralization show lymphoma-like transcriptomes in patients with chronic HCV infection.

BACKGROUND: Chronic HCV infection leads to a complex interplay with adaptive immune cells that may result in B cell dyscrasias like cryoglobulinemia or lymphoma. While direct-acting antiviral therapy has decreased the incidence of severe liver damage, its effect on extrahepatic HCV manifestations such as B cell dyscrasias is still unclear. METHODS: We sequenced B cell receptor (BCR) repertoires in patients with chronic HCV mono-infection and patients with HCV with a sustained virological response (SVR) after direct-acting antiviral therapy. This data set was mined for highly neutralizing HCV antibodies and compared to a diffuse large B cell lymphoma data set. The TKO model was used to test the signaling strength of selected B-BCRs in vitro. Single-cell RNA sequencing of chronic HCV and HCV SVR samples was performed to analyze the transcriptome of B cells with HCV-neutralizing antigen receptors. RESULTS: We identified a B cell fingerprint with high richness and somatic hypermutation in patients with chronic HCV and SVR. Convergence to specific immunoglobulin genes produced high-connectivity complementarity-determining region 3 networks. In addition, we observed that IGHV1-69 CDR1 and FR3 mutations characterizing highly neutralizing HCV antibodies corresponded to recurrent point mutations found in clonotypic BCRs of high-grade lymphomas. These BCRs did not show autonomous signaling but a lower activation threshold in an in vitro cell model for the assessment of BCR signaling strength. Single-cell RNA sequencing revealed that B cells carrying these point mutations showed a persisting oncogenic transcriptome signature with dysregulation in signaling nodes such as CARD11, MALT1, RelB, MAPK, and NFAT. CONCLUSIONS: We provide evidence that lymphoma-like cells derive from the anti-HCV immune response. In many patients, these cells persist for years after SVR and can be interpreted as a mechanistic basis for HCV-related B cell dyscrasias and increased lymphoma risk even beyond viral elimination.

Trifluridine/Tipiracil Based Chemoradiation in locally Advanced Rectal Cancer: The Phase I/II TARC Trial.

BACKGROUND: Optimizing functional outcomes and securing long-term remissions are key goals in managing patients with locally advanced rectal cancer. In this proof-of-concept study, we set out to further optimize neoadjuvant therapy by integrating the radiosensitizer trifluridine/tipiracil and explore the potential of cell free tumor DNA (ctDNA) to monitor residual disease. METHODS: About 10 patients were enrolled in the phase I dose finding part which followed a 3 + 3 dose escalation design. Tipiracil/trifluridine was administered concomitantly to radiotherapy. ctDNA monitoring was performed before and after chemoradiation with patient-individualized digital droplet PCRs. RESULTS: No dose-limiting toxicities were observed at the maximum tolerated dose level of 2 × 35 mg/m² trifluridine/tipiracil. There were 9 grade 3 adverse events, of which 8 were hematologic with anemia and leukopenia. Chemoradiation yielded a pathological complete response in 1 out of 8 assessable patients, downstaging in nearly all patients, and 1 clinical complete response referred for watchful waiting. Three of 4 assessable patients with residual tumor cells at pathological assessment remained liquid biopsy positive after chemoradiation, but 1 turned negative. CONCLUSION: In this exploratory phase I trial, the novel combination of neoadjuvant trifluridine/tipiracil and radiotherapy proved to be feasible, tolerable, and effective. However, the application of liquid biopsy as a potential marker for therapeutic de-escalation in the neoadjuvant setting requires additional research and prospective validation. The trial was registered at ClinicalTrials.gov: NCT04177602.

Higher-Order Least Squares: Assessing Partial Goodness of Fit of Linear Causal Models.

We introduce a simple diagnostic test for assessing the overall or partial goodness of fit of a linear causal model with errors being independent of the covariates. In particular, we consider situations where hidden confounding is potentially present. We develop a method and discuss its capability to distinguish between covariates that are confounded with the response by latent variables and those that are not. Thus, we provide a test and methodology for partial goodness of fit. The test is based on comparing a novel higher-order least squares principle with ordinary least squares. In spite of its simplicity, the proposed method is extremely general and is also proven to be valid for high-dimensional settings. Supplementary materials for this article are available online.

Detection of disease-specific signatures in B cell repertoires of lymphomas using machine learning.

The classification of B cell lymphomas-mainly based on light microscopy evaluation by a pathologist-requires many years of training. Since the B cell receptor (BCR) of the lymphoma clonotype and the microenvironmental immune architecture are important features discriminating different lymphoma subsets, we asked whether BCR repertoire next-generation sequencing (NGS) of lymphoma-infiltrated tissues in conjunction with machine learning algorithms could have diagnostic utility in the subclassification of these cancers. We trained a random forest and a linear classifier via logistic regression based on patterns of clonal distribution, VDJ gene usage and physico-chemical properties of the top-n most frequently represented clonotypes in the BCR repertoires of 620 paradigmatic lymphoma samples-nodular lymphocyte predominant B cell lymphoma (NLPBL), diffuse large B cell lymphoma (DLBCL) and chronic lymphocytic leukemia (CLL)-alongside with 291 control samples. With regard to DLBCL and CLL, the models demonstrated optimal performance when utilizing only the most prevalent clonotype for classification, while in NLPBL-that has a dominant background of non-malignant bystander cells-a broader array of clonotypes enhanced model accuracy. Surprisingly, the straightforward logistic regression model performed best in this seemingly complex classification problem, suggesting linear separability in our chosen dimensions. It achieved a weighted F1-score of 0.84 on a test cohort including 125 samples from all three lymphoma entities and 58 samples from healthy individuals. Together, we provide proof-of-concept that at least the 3 studied lymphoma entities can be differentiated from each other using BCR repertoire NGS on lymphoma-infiltrated tissues by a trained machine learning model.

NKp44/HLA-DP-dependent regulation of CD8 effector T cells by NK cells.

Although natural killer (NK) cells are recognized for their modulation of immune responses, the mechanisms by which human NK cells mediate immune regulation are unclear. Here, we report that expression of human leukocyte antigen (HLA)-DP, a ligand for the activating NK cell receptor NKp44, is significantly upregulated on CD8+ effector T cells, in particular in human cytomegalovirus (HCMV)+ individuals. HLA-DP+ CD8+ T cells expressing NKp44-binding HLA-DP antigens activate NKp44+ NK cells, while HLA-DP+ CD8+ T cells not expressing NKp44-binding HLA-DP antigens do not. In line with this, frequencies of HLA-DP+ CD8+ T cells are increased in individuals not encoding for NKp44-binding HLA-DP haplotypes, and contain hyper-expanded CD8+ T cell clones, compared to individuals expressing NKp44-binding HLA-DP molecules. These findings identify a molecular interaction facilitating the HLA-DP haplotype-specific editing of HLA-DP+ CD8+ T cell effector populations by NKp44+ NK cells and preventing the generation of hyper-expanded T cell clones, which have been suggested to have increased potential for autoimmunity.

SARS-CoV-2-associated T-cell infiltration in the central nervous system.

Objectives: Infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes coronavirus disease 2019 (COVID-19). Although an acute SARS-CoV-2 infection mainly presents with respiratory illness, neurologic symptoms and sequelae are increasingly recognised in the long-term treatment of COVID-19 patients. The pathophysiology and the neuropathogenesis behind neurologic complications of COVID-19 remain poorly understood, but mounting evidence points to endothelial dysfunction either directly caused by viral infection or indirectly by inflammatory cytokines, followed by a local immune response that may include virus-specific T cells. However, the type and role of central nervous system-infiltrating T cells in COVID-19 are complex and not fully understood. Methods: We analysed distinct anatomical brain regions of patients who had deceased as a result of COVID-19-associated pneumonia or complications thereof and performed T cell receptor Vß repertoire sequencing. Clonotypes were analysed for SARS-CoV-2 association using public TCR repertoire data. Results: Our descriptive study demonstrates that SARS-CoV-2-associated T cells are found in almost all brain areas of patients with fatal COVID-19 courses. The olfactory bulb, medulla and cerebellum were brain regions showing the most SARS-CoV-2 specific sequence patterns. Neuropathological workup demonstrated primary CD8+ T-cell infiltration with a perivascular infiltration pattern. Conclusion: Future research is needed to better define the relationship between T-cell infiltration and neurological symptoms and its long-term impact on patients' cognitive and mental health.

Mutation-specific CAR T cells as precision therapy for IGLV3-21R110 expressing high-risk chronic lymphocytic leukemia.

The concept of precision cell therapy targeting tumor-specific mutations is appealing but requires surface-exposed neoepitopes, which is a rarity in cancer. B cell receptors (BCR) of mature lymphoid malignancies are exceptional in that they harbor tumor-specific-stereotyped sequences in the form of point mutations that drive self-engagement of the BCR and autologous signaling. Here, we use a BCR light chain neoepitope defined by a characteristic point mutation (IGLV3-21R110) for selective targeting of a poor-risk subset of chronic lymphocytic leukemia (CLL) with chimeric antigen receptor (CAR) T cells. We develop murine and humanized CAR constructs expressed in T cells from healthy donors and CLL patients that eradicate IGLV3-21R110 expressing cell lines and primary CLL cells, but neither cells expressing the non-pathogenic IGLV3-21G110 light chain nor polyclonal healthy B cells. In vivo experiments confirm epitope-selective cytolysis in xenograft models in female mice using engrafted IGLV3-21R110 expressing cell lines or primary CLL cells. We further demonstrate in two humanized mouse models lack of cytotoxicity towards human B cells. These data provide the basis for advanced approaches of resistance-preventive and biomarker-guided cellular targeting of functionally relevant lymphoma driver mutations sparing normal B cells.

SARS-CoV-2 vaccination may mitigate dysregulation of IL-1/IL-18 and gastrointestinal symptoms of the post-COVID-19 condition.

The rapid development of safe and effective vaccines helped to prevent severe disease courses after SARS-CoV-2 infection and to mitigate the progression of the COVID-19 pandemic. While there is evidence that vaccination may reduce the risk of developing post-COVID-19 conditions (PCC), this effect may depend on the viral variant. Therapeutic effects of post-infection vaccination have been discussed but the data for individuals with PCC remains inconclusive. In addition, extremely rare side effects after SARS-CoV-2 vaccination may resemble the heterogeneous PCC phenotype. Here, we analyze the plasma levels of 25 cytokines and SARS-CoV-2 directed antibodies in 540 individuals with or without PCC relative to one or two mRNA-based COVID-19 vaccinations as well as in 20 uninfected individuals one month after their initial mRNA-based COVID-19 vaccination. While none of the SARS-CoV-2 naïve individuals reported any persisting sequelae or exhibited PCC-like dysregulation of plasma cytokines, we detected lower levels of IL-1ß and IL-18 in patients with ongoing PCC who received one or two vaccinations at a median of six months after infection as compared to unvaccinated PCC patients. This reduction correlated with less frequent reporting of persisting gastrointestinal symptoms. These data suggest that post-infection vaccination in patients with PCC might be beneficial in a subgroup of individuals displaying gastrointestinal symptoms.

Tolerability and efficacy of the cancer vaccine UV1 in patients with recurrent or metastatic PD-L1 positive head and neck squamous cell carcinoma planned for first-line treatment with pembrolizumab - the randomized phase 2 FOCUS trial.

Background: Globally, head and neck squamous cell carcinoma (HNSCC) is the seventh most common malignancy. Despite aggressive multimodal treatment approaches, recurrent and/or metastatic (R/M) disease develops in >50% of patients. In this setting, pembrolizumab was approved for patients with PD-L1 expression. However, response rates with checkpoint inhibitor monotherapy remain limited and strategies to strengthen tumor-directed immune responses are needed. Objective: The FOCUS trial is designed to estimate the effectiveness of UV1 vaccination in combination with pembrolizumab versus pembrolizumab as a single agent in patients with R/M HNSCC. Methods and analysis: The FOCUS trial is a two-armed, randomized, multicenter phase II study which was designed to evaluate the efficacy and feasibility of the hTERT-targeted cancer vaccine UV1 as add-on to pembrolizumab in the 1st line treatment of patients with R/M PD-L1 positive (combined positive score ≥1) HNSCC. Secondary objectives are the exploration of patient subgroups most likely deriving benefit from this novel combination and the establishment of liquid biopsy tumor monitoring in HNSCC. Ethics and dissemination: This clinical study was designed and will be conducted in compliance with Good Clinical Practice and in accordance with the Declaration of Helsinki. It is intended to publish the results of this study in peer-reviewed scientific journals and to present its content at academic conferences. Conclusions: A significant number of patients with R/M HNSCC are frail and may not tolerate chemotherapy, these patients may only be suitable for pembrolizumab monotherapy. However, long term disease stabilizations remain the exception and there is a need for the development of efficacious combination regimens for this patient population. The FOCUS study aims to optimize treatment of R/M HNSCC patients with this promising new treatment approach. Clinical Trial Registration: https://clinicaltrials.gov/study/NCT05075122, identifier NCT05075122.

Ramucirumab, Avelumab, and Paclitaxel as Second-Line Treatment in Esophagogastric Adenocarcinoma: The Phase 2 RAP (AIO-STO-0218) Nonrandomized Controlled Trial.

Importance: Adding immune checkpoint inhibitors to chemotherapy has been associated with improved outcomes in metastatic esophagogastric adenocarcinoma, but treatment combinations and optimal patient selection need to be established. Objective: To investigate the efficacy and tolerability of the programmed cell death ligand 1 (PDL-1) inhibitor avelumab with paclitaxel plus ramucirumab. Design, Setting, and Participants: This multicenter, single-group, phase 2 nonrandomized controlled trial was conducted among patients with second-line metastatic esophagogastric adenocarcinoma. Patients pretreated with platinum plus fluoropyrimidine between April 2019 and November 2020 across 10 German centers (median follow-up, 27.4 months [95% CI 22.0-32.9 months]) were included. Data analysis was performed from January to December 2022. Interventions: Patients received ramucirumab at 8 mg/kg on days 1 and 15, avelumab at 10 mg/kg on days 1 and 15, and paclitaxel at 80 mg/m2 on days 1, 8, and 15 every 4 weeks. Main Outcomes and Measures: The prespecified primary end point was overall survival (OS) rate at 6 months, with the experimental therapy considered insufficiently active with an OS rate of 50% or less and a promising candidate with an OS rate of 65% or greater. Results: Of 60 enrolled patients, 59 patients (median [range] age, 64 [18-81] years; 47 males [70.7%]) were evaluable, including 30 patients with metastatic adenocarcinoma of the stomach and 29 patients with gastroesophageal junction. All patients were pretreated with platinum plus fluoropyrimidine, and 40 patients (67.8%) had received prior taxanes; 24 of 56 evaluable patients (42.9%) had a PDL-1 combined positive score (CPS) of 5 or greater, centrally assessed. The OS rate at 6 months was 71.2% (95% CI, 61.5%-83.7%). The median OS in the intention-to-treat population (59 patients) was 10.6 months (95% CI, 8.4-12.8 months) overall. Among patients assessable by central pathology, median OS was 9.4 months (95% CI, 7.2-11.7 months) in 32 patients with a PDL-1 CPS less than 5 and 14.0 months (95% CI, 6.0-22.1 months) in 24 patients with a PDL-1 CPS of 5 or greater (P = .25). Treatment was generally well tolerated, without unexpected toxicities. Patients with higher vs lower than median T cell repertoire richness showed an increased median OS of 20.4 months (95% CI, 7.7-33.0 months) compared with 8.3 months (95% CI, 3.7-12.9 months; hazard ratio, 0.43; 95% CI, 0.23-0.81; P = .008). Patients with lower vs higher than median cell-free DNA burden had a median OS of 19.2 months (95% CI, 8.9-29.6 months) compared with 7.3 months (95% CI, 3.2-11.4 months; hazard ratio, 0.30; 95% CI, 0.16-0.59; P < .001). Conclusions and relevance: In this study, the combination of avelumab with paclitaxel plus ramucirumab showed favorable efficacy and tolerability in the second-line treatment for metastatic esophagogastric adenocarcinoma. A PDL-1 CPS score of 5 or greater, cell-free DNA level less than the median, and T cell repertoire richness greater than the median were associated with increased median OS. Trial Registration: ClinicalTrials.gov Identifier: NCT03966118.

Machine learning analysis of humoral and cellular responses to SARS-CoV-2 infection in young adults.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) induces B and T cell responses, contributing to virus neutralization. In a cohort of 2,911 young adults, we identified 65 individuals who had an asymptomatic or mildly symptomatic SARS-CoV-2 infection and characterized their humoral and T cell responses to the Spike (S), Nucleocapsid (N) and Membrane (M) proteins. We found that previous infection induced CD4 T cells that vigorously responded to pools of peptides derived from the S and N proteins. By using statistical and machine learning models, we observed that the T cell response highly correlated with a compound titer of antibodies against the Receptor Binding Domain (RBD), S and N. However, while serum antibodies decayed over time, the cellular phenotype of these individuals remained stable over four months. Our computational analysis demonstrates that in young adults, asymptomatic and paucisymptomatic SARS-CoV-2 infections can induce robust and long-lasting CD4 T cell responses that exhibit slower decays than antibody titers. These observations imply that next-generation COVID-19 vaccines should be designed to induce stronger cellular responses to sustain the generation of potent neutralizing antibodies.

First-line treatment of unresectable or metastatic HER2 positive esophagogastric adenocarcinoma: liquid biomarker analysis of the phase 2 INTEGA trial.

BACKGROUND: The addition of nivolumab to trastuzumab and chemotherapy in first-line unresectable or metastatic HER2 positive esophagogastric adenocarcinoma (HER2+ EGA) results in long progression-free and overall survival as shown by the INTEGA (ipilimumab or FOLFOX in combination with nivolumab and trastuzumab in HER2 positive esophagogastric adenocarcinoma) trial. This trial suggested that the chemotherapy backbone is needed in an unselected HER2+ patient population. Yet, it remains an open question if there are specific patient subsets that may benefit from an enhanced immunotherapeutic but chemotherapy-free approach. METHODS: We analyzed blood T cell repertoire metrics determined by next-generation sequencing, circulating tumor cell (CTC) counts detected by CellSearch and their expression of HER2 and PD-L1 as potential liquid biomarkers predicting outcomes on ipilimumab versus FOLFOX (folinic acid, FOL, fluorouracil, F, oxaliplatin, OX) chemotherapy added to a backbone of trastuzumab and nivolumab in patients with HER2+ EGA in the INTEGA trial population. RESULTS: Patients with two out of three baseline-determined liquid biomarkers-high T cell repertoire richness, absence of CTCs or HER2-expression on CTCs-made up approximately 44% of HER2+ EGA cases and did not show compromise in efficacy if treated with a chemotherapy-free regimen. Long-term responders showing a progression-free survival of >12 months were enriched in this biomarker triad, especially if treated on the chemotherapy-free arm. CONCLUSION: Prospective validation of this liquid biomarker triad is needed to molecularly define HER2+ EGA patient subsets with different needs in the first-line systemic treatment setting.

T cell repertoire breadth is associated with the number of acute respiratory infections in the LoewenKIDS birth cohort.

We set out to gain insight into peripheral blood B and T cell repertoires from 120 infants of the LoewenKIDS birth cohort to investigate potential determinants of early life respiratory infections. Low antigen-dependent somatic hypermutation of B cell repertoires, as well as low T and B cell repertoire clonality, high diversity, and high richness especially in public T cell clonotypes reflected the immunological naivety at 12 months of age when high thymic and bone marrow output are associated with relatively few prior antigen encounters. Infants with inadequately low T cell repertoire diversity or high clonality showed higher numbers of acute respiratory infections over the first 4 years of life. No correlation of T or B cell repertoire metrics with other parameters such as sex, birth mode, older siblings, pets, the onset of daycare, or duration of breast feeding was noted. Together, this study supports that-regardless of T cell functionality-the breadth of the T cell repertoire is associated with the number of acute respiratory infections in the first 4 years of life. Moreover, this study provides a valuable resource of millions of T and B cell receptor sequences from infants with available metadata for researchers in the field.

Autoantigen-selected B cells are bystanders in spontaneous T cell-driven experimental autoimmune hepatitis.

Autoreactive B cells are considered pathogenic drivers in many autoimmune diseases; however, it is not clear whether autoimmune B cells are invariably pathogenic or whether they can also arise as bystanders of T cell-driven autoimmune pathology. Here, we studied the B cell response in an autoantigen- and CD4+ T cell-driven model of autoimmune hepatitis (AIH), the Alb-iGP_Smarta mouse in which expression of a viral model antigen (GP) in hepatocytes and its recognition by GP-specific CD4+ T cells causes spontaneous AIH-like disease. T cell-driven AIH in Alb-iGP_Smarta mice was marked by autoantibodies and hepatic infiltration of plasma cells and B cells, particularly of isotype-switched memory B cells, indicating antigen-driven selection and activation. Immunosequencing of B cell receptor repertoires confirmed B cell expansion selectively in the liver, which was most likely driven by the hepatic GP model antigen, as indicated by branched networks of connected sequences and elevated levels of IgG antibodies to GP. However, intrahepatic B cells did not produce increased levels of cytokines and their depletion with anti-CD20 antibody did not alter the CD4+ T cell response in Alb-iGP_Smarta mice. Moreover, B cell depletion did not prevent spontaneous liver inflammation and AIH-like disease in Alb-iGP_Smarta mice. In conclusion, selection and isotype-switch of liver-infiltrating B cells was dependent on the presence of CD4+ T cells recognizing liver antigen. However, recognition of hepatic antigen by CD4+ T cells and CD4+ T cell-mediated hepatitis was not dependent on B cells. Thus, autoreactive B cells can be bystanders and need not be drivers of liver inflammation in AIH.

Immune signatures in variant syndromes of primary biliary cholangitis and autoimmune hepatitis.

BACKGROUND: Variant syndromes of autoimmune hepatitis (AIH) and primary biliary cholangitis (PBC) share diagnostic features of both entities, but their immunological underpinnings remain largely unexplored. METHODS: We performed blood profiling of 23 soluble immune markers and immunogenetics in a cohort of 88 patients with autoimmune liver diseases (29 typical AIH, 31 typical PBC and 28 with clinically PBC/AIH variant syndromes). The association with demographical, serological and clinical features was analyzed. RESULTS: While T and B cell receptor repertoires were highly skewed in variant syndromes compared to healthy controls, these biases were not sufficiently discriminated within the spectrum of autoimmune liver diseases. High circulating checkpoint molecules sCD25, sLAG-3, sCD86 and sTim-3 discriminated AIH from PBC on top of classical parameters such as transaminases and immunoglobulin levels. In addition, a second cluster of correlated soluble immune factors encompassing essentially TNF, IFNγ, IL12p70, sCTLA-4, sPD-1 and sPD-L1 appeared characteristic of AIH. Cases with complete biochemical responses to treatment generally showed a lower level of dysregulation. Unsupervised hierarchical clustering of classical and variant syndromes identified two pathological immunotypes consisting predominantly of either AIH or PBC cases. Variant syndromes did not form a separate group, but clustered together with either classical AIH or PBC. Clinically, patient with AIH-like variant syndromes were less likely to be able discontinue immunosuppressive treatment. CONCLUSIONS: Our analyses suggest that variants of immune mediated liver diseases may represent an immunological spectrum from PBC to AIH-like disease reflected by their pattern of soluble immune checkpoint molecules rather than separate entities.

Circulating Tumor DNA in Head and Neck Squamous Cell Carcinoma.

Tumors shed cell-free DNA (cfDNA) into the plasma. "Liquid biopsies" are a diagnostic test to analyze cfDNA in order to detect minimal residual cancer, profile the genomic tumor landscape, and monitor cancers non-invasively over time. This technique may be useful in patients with head and neck squamous cell carcinoma (HNSCC) due to genetic tumor heterogeneity and limitations in imaging sensitivity. However, there are technical challenges that need to be overcome for the widespread use of liquid biopsy in the clinical management of these patients. In this review, we discuss our current understanding of HNSCC genetics and the role of cfDNA genomic analyses as an emerging precision diagnostic tool.

Liquid biomarkers of macrophage dysregulation and circulating spike protein illustrate the biological heterogeneity in patients with post-acute sequelae of COVID-19.

Post-acute sequelae of COVID-19 (PASC) are long-term consequences of SARS-CoV-2 infection that can substantially impair the quality of life. Underlying mechanisms ranging from persistent viruses to innate and adaptive immune dysregulation have been discussed. Here, we profiled the plasma of 181 individuals from the cohort study for digital health research in Germany (DigiHero), including individuals after mild to moderate COVID-19 with or without PASC and uninfected controls. We focused on soluble factors related to monocyte/macrophage biology and on circulating SARS-CoV-2 spike (S1) protein as a potential biomarker for persistent viral reservoirs. At a median time of 8 months after infection, we found pronounced dysregulation in almost all tested soluble factors, including both pro-inflammatory and pro-fibrotic cytokines. These immunological perturbations were remarkably independent of ongoing PASC symptoms per se, but further correlation and regression analyses suggested PASC-specific patterns involving CCL2/MCP-1 and IL-8 that either correlated with sCD162, sCD206/MMR, IFN-α2, IL-17A and IL-33, or IL-18 and IL-23. None of the analyzed factors correlated with the detectability or levels of circulating S1, indicating that this represents an independent subset of patients with PASC. These data confirm prior evidence of immune dysregulation and persistence of viral protein in PASC and illustrate its biological heterogeneity that still awaits correlation with clinically defined PASC subtypes.

PD-L1 Amino Acid Position 88 Represents a Hotspot for PD-L1 Stability With Relevance for PD-L1 Inhibition.

The two most common antibody targeting principles in oncology are the induction of direct antitumor effects and the release of antitumor T cell immunity by immune checkpoint blockade. These two principles, however, may be overlapping if the targeted checkpoint molecule is not located on the immune cell but on the tumor cell itself. Secondary resistance by epitope escape may therefore remain a challenge in both settings. We previously reported epitope escape through L88S and truncating programmed cell death ligand 1 (PD-L1) gene mutations in colorectal cancer patients on selective pressure with avelumab, a PD-L1-directed checkpoint blocker that-in addition to T cell disinhibition-allows direct tumor cell killing via its unmodified Fc portion. Here, we confirmed this principle by liquid biopsy monitoring in a colorectal cancer patient from an independent clinical trial. In this patient, both PD-L1 L88E and L88fs mutations emerged under selective pressure with avelumab. By ectopically expressing PD-L1 L88E, we show that this mutation leads to a reduction of full-length glycosylated PD-L1 and greatly reduced avelumab surface binding. Further experiments indicated that PD-L1 L88E represents a phosphomimetic variant of PD-L1 L88S leading to loss of protein stability and increased proteasomal degradation. The association of this PD-L1 mutation with the high-affinity FCGR3A single nucleotide polymorphism rs396991 confirms prior evidence that patients harboring this polymorphism experience the strongest selective pressure by avelumab. Together, position 88 of PD-L1 is a hotspot residue critically regulating PD-L1 cell surface expression with clinical significance in the context of immune checkpoint blockade.