Antibodies against endogenous retroviruses promote lung cancer immunotherapy

B cells are frequently found in the margins of solid tumours as organized follicles in ectopic lymphoid organs called tertiary lymphoid structures (TLS). Although TLS have been found to correlate with improved patient survival and response to immune checkpoint blockade (ICB), the underlying mechanisms of this association remain elusive. Here we investigate lung-resident B cell responses in patients from the TRACERx 421 (Tracking Non-Small-Cell Lung Cancer Evolution Through Therapy) and other lung cancer cohorts, and in a recently established immunogenic mouse model for lung adenocarcinoma. We find that both human and mouse lung adenocarcinomas elicit local germinal centre responses and tumour-binding antibodies, and further identify endogenous retrovirus (ERV) envelope glycoproteins as a dominant anti-tumour antibody target. ERV-targeting B cell responses are amplified by ICB in both humans and mice, and by targeted inhibition of KRAS(G12C) in the mouse model. ERV-reactive antibodies exert anti-tumour activity that extends survival in the mouse model, and ERV expression predicts the outcome of ICB in human lung adenocarcinoma. Finally, we find that effective immunotherapy in the mouse model requires CXCL13-dependent TLS formation. Conversely, therapeutic CXCL13 treatment potentiates anti-tumour immunity and synergizes with ICB. Our findings provide a possible mechanistic basis for the association of TLS with immunotherapy response

Histiocytic sarcoma progressing from follicular lymphoma and mimicking acquired hemophagocytic lymphohistiocytosis

Isolated myeloid sarcoma (MS) is a rare malignancy in which myeloid blast forms tumors at various locations while the bone marrow (BM) remains cytomorphologically free from disease. We analyzed isolated MS from four patients and their BMs at initial diagnosis and follow-up, using a custom next-generation sequencing (NGS) panel. We observed possible clonal evolution and a clonal hematopoiesis of indeterminate potential (CHIP)-like finding in the BM of one of three cases with detectable mutations. Clinical presentation of one patient suggested extramedullary confined homing of blasts to distal sites in the relapse situation still sparing the BM. In summary, our findings shall motivate future work regarding signals of extramedullary blast trafficking and clonal evolution in MS

Optical Genome Mapping as a Diagnostic Tool in Pediatric Acute Myeloid Leukemia

Pediatric AML is characterized by numerous genetic aberrations (chromosomal translocations, deletions, insertions) impacting its classification for risk of treatment failure. Aberrations are described by classical cytogenetic procedures (karyotyping, FISH), which harbor limitations (low resolution, need for cell cultivation, cost-intensiveness, experienced staff required). Optical Genome Mapping (OGM) is an emerging chip-based DNA technique combining high resolution (~500 bp) with a relatively short turnaround time. Twenty-four pediatric patients with AML, bi-lineage leukemia, and mixed-phenotype acute leukemia were analyzed by OGM, and the results were compared with cytogenetics. Results were discrepant in 17/24 (70%) cases, including 32 previously unknown alterations called by OGM only. One newly detected deletion and two translocations were validated by primer walking, breakpoint-spanning PCR, and DNA sequencing. As an added benefit, in two cases, OGM identified a new minimal residual disease (MRD) marker. Comparing impact on risk stratification in de novo AML, 19/20 (95%) cases had concordant results while only OGM unraveled another high-risk aberration. Thus, OGM considerably expands the methodological spectrum to optimize the diagnosis of pediatric AML via the identification of new aberrations. Results will contribute to a better understanding of leukemogenesis in pediatric AML. In addition, aberrations identified by OGM may provide markers for MRD monitoring

Human CD8+ CD57- T_EMRA cells: Too young to be called "old"

<div><p>End-stage differentiation of antigen-specific T-cells may precede loss of immune responses against e.g. viral infections after allogeneic stem cell transplantation (SCT). Antigen-specific CD8+ T-cells detected by HLA/peptide multimers largely comprise CD45RA-/CCR7- effector memory (T_EM) and CD45RA+/CCR7- T_EMRA subsets. A majority of terminally differentiated T-cells is considered to be part of the heterogeneous T_EMRA subset. The senescence marker CD57 has been functionally described in memory T-cells mainly composed of central memory (T_CM) and T_EM cells. However, its role specifically in T_EMRA cells remained undefined. Here, we investigated the relevance of CD57 to separate human CD8+ T_EMRA cells into functionally distinct subsets. CD57- CD8+ T_EMRA cells isolated from healthy donors had considerably longer telomeres and showed significantly more BrdU uptake and IFN-γ release upon stimulation compared to the CD57+ counterpart. Cytomegalovirus (CMV) specific T-cells isolated from patients after allogeneic SCT were purified into CD57+ and CD57- T_EMRA subsets. CMV specific CD57- T_EMRA cells had longer telomeres and a considerably higher CMV peptide sensitivity in BrdU uptake and IFN-γ release assays compared to CD57+ T_EMRA cells. In contrast, CD57+ and CD57- T_EMRA cells showed comparable peptide specific cytotoxicity. Finally, CD57- CD8+ T_EMRA cells partially changed phenotypically into T_EM cells and gained CD57 expression, while CD57+ CD8+ T_EMRA cells hardly changed phenotypically and showed considerable cell death after in vitro stimulation. To the best of our knowledge, these data show for the first time that CD57 separates CD8+ T_EMRA cells into a terminally differentiated CD57+ population and a so far functionally undescribed “young” CD57- T_EMRA subset with high proliferative capacity and differentiation plasticity.</p></div

Distribution of CD57+ cells in CD8+ T cell subsets.

<p>(A-B) Gating strategy for the assessment of the CD57 distribution in subsets of (A) overall CD8+ T cells and (B) CMV specific CD8+ T cells. (A) Shown is one representative example of the CD57 distribution within CD8+ T_N, T_CM, T_EM and T_EMRA cells of 6 healthy individuals. (B) Shown is one representative example of the CD57 distribution within CD8+ CMV tetramer+ T_EM and T_EMRA cells of 10 patients after allogeneic SCT.</p

Phenotypic and functional characterization of CMV tetramer+ cells.

<p><b>(A)</b> CD8+ CMV tetramer+ T cells were FACS sorted from the peripheral blood of 3 patients after allogeneic SCT and in vitro expanded on autologous feeder cells. Depicted is the T_EM and T_EMRA subset distribution within CD8+ CMV HLA/tetramer+ T cells (left) and CD57+ distribution within CD8+ CMV HLA/tetramer+ T_EMRA cells (right) in the peripheral blood compared to after in vitro expansion of FACS sorted CD8+ CMV tetramer+ T cells. Y-axis: % subset distribution within CD8+ CMV HLA/tetramer+ T cells and CD8+ CMV HLA/tetramer+ T_EMRA cells. Error bars indicate standard deviation. (B) Sorting strategy for viable in vitro expanded CD8+ CMV HLA/tetramer+ CD8+ T cells for CD45RA and CD57 allowing functional analysis. (C) Absolute telomere length directly after sorting. (D) BrdU uptake 4 days after stimulation with CD14+ monocytes loaded with increasing concentrations of the relevant HLA/CMV peptide. (E) INF-γ release in the supernatant from the BrdU uptake assay. (F) Specific lysis of CFSE labelled PHA blasts loaded with increasing concentrations of the relevant HLA/CMV peptide. Significance was calculated using Mann-Whitney-U test. * indicates p<0.05, ** indicates p<0.01, ns indicates not significant.</p