CD74 supports accumulation and function of regulatory T cells in tumors.

Regulatory T cells (Tregs) are plastic cells playing a pivotal role in the maintenance of immune homeostasis. Tregs actively adapt to the microenvironment where they reside; as a consequence, their molecular and functional profiles differ among tissues and pathologies. In tumors, the features acquired by Tregs remains poorly characterized. Here, we observe that human tumor-infiltrating Tregs selectively overexpress CD74, the MHC class II invariant chain. CD74 has been previously described as a regulator of antigen-presenting cell biology, however its function in Tregs remains unknown. CD74 genetic deletion in human primary Tregs reveals that CD74KO Tregs exhibit major defects in the organization of their actin cytoskeleton and intracellular organelles. Additionally, intratumoral CD74KO Tregs show a decreased activation, a drop in Foxp3 expression, a low accumulation in the tumor, and consistently, they are associated with accelerated tumor rejection in preclinical models in female mice. These observations are unique to tumor conditions as, at steady state, CD74KO-Treg phenotype, survival, and suppressive capacity are unaffected in vitro and in vivo. CD74 therefore emerges as a specific regulator of tumor-infiltrating Tregs and as a target to interfere with Treg anti-tumor activity.

Recommendations for Post-Operative RadioTherapy After Complete Resection of Thymoma-a French DELPHI Consensus Initiative.

INTRODUCTION: Thymomas are rare intrathoracic malignancies that can relapse after surgery. Whether or not Post-Operative RadioTherapy (PORT) should be delivered after surgery remains a major issue. RADIORYTHMIC is an ongoing, multicenter, randomized phase 3 trial addressing this question in patients with completely R0 resected Masaoka-Koga stage IIb/III thymoma. Experts in the field met to develop recommendations for PORT. METHODS: A scientific committee from the RYTHMIC network identified key issues regarding the modalities of PORT in completely resected thymoma. A DELPHI method was used to question 24 national experts, with 115 questions regarding the following: (1) imaging techniques, (2) clinical target volume (CTV) and margins, (3) dose constraints to organs at risk, (4) dose and fractionation, and (5) follow-up and records. Consensus was defined when opinions reached more than or equal to 80% agreement. RESULTS: We established the following recommendations: preoperative contrast-enhanced computed tomography (CT) scan is recommended (94% agreement); optimization of radiation delivery includes either a four-dimensional CT-based planning (82% agreement), a breath-holding inspiration breath-hold-based planning, or daily control CT imaging (81% agreement); imaging fusion based on cardiovascular structures of preoperative and planning CT scan is recommended (82% agreement); right coronary and left anterior descending coronary arteries should be delineated as cardiac substructures (88% agreement); rotational RCMI/volumetric modulated arc therapy is recommended (88% agreement); total dose is 50 Gy (81% agreement) with 1.8 to 2 Gy per fraction (94% agreement); cardiac evaluation and follow-up for patients with history of cardiovascular disease are recommended (88% agreement) with electrocardiogram and evaluation of left ventricular ejection fraction at 5 years and 10 years. CONCLUSION: This is the first consensus for PORT in thymoma. Implementation will help to harmonize practices.

Management of sotorasib-related adverse events and hepatotoxicities following anti-PD-(L)1 therapy: Experience with sotorasib in two French anti-cancer centers and practical guidance proposal.

INTRODUCTION: Sotorasib is a first-in-class KRASG12C inhibitor that showed significant clinical activity in KRASG12C-mutated non-small cell lung cancer (NSCLC). The most frequent grade 3 or 4 sotorasib-related adverse events (AEs) were diarrhea (4-12 %) and hepatotoxicity (10.1-15.1 %). Data is lacking about the management of these AEs, especially in patients receiving sequential anti-PD-(L)1 and sotorasib therapy. Our aim was to report the management of grade ≥ 2 sotorasib-related AEs in real-world setting and to propose practical guidance for the management of grade ≥ 2 sotorasib-related AEs and more generally KRASG12C inhibitors-related AEs. MATERIALS AND METHODS: Records from all consecutive patients who initiated sotorasib through expanded access program in two French anti-cancer centers from January 1st 2021 to April 1st 2023 were reviewed to identify and grade sotorasib-related AEs, according to NCI-CTCAE v5.0., and to collect AEs management data. Patients were included in the analysis if they presented a grade ≥ 2 sotorasib-related AE. RESULTS: From 57 patients identified, 21 met inclusion criteria including eighteen (86 %) who received sequential anti-PD-(L)1 and sotorasib therapy. Hepatotoxicity (76 %) and diarrhea (24 %) were the most common grade ≥ 2 sotorasib-related AEs. Among the 16 patients with a grade ≥ 2 hepatotoxicity, 12 (75 %) definitely discontinued sotorasib, among which 9 (56 %) after dose reductions and rechallenge, and five (32 %) received corticosteroids, allowing only one patient to resume sotorasib. Diarrhea and nausea were usually manageable and not associated with sotorasib discontinuation. We propose a step-by-step management practical guidance for sotorasib-related hepatotoxicity based on dose-reduction and careful monitoring. Liver biopsy is strongly encouraged for grade 3 and 4 hepatotoxicity to assess candidates for corticosteroids. DISCUSSION: The experience with sotorasib might help better prevent, screen and manage sotorasib-related and other KRASG12C inhibitors-related AEs, particularly hepatotoxicity.

Repeated peripheral infusions of anti-EGFRvIII CAR T cells in combination with pembrolizumab show no efficacy in glioblastoma: a phase 1 trial.

We previously showed that chimeric antigen receptor (CAR) T-cell therapy targeting epidermal growth factor receptor variant III (EGFRvIII) produces upregulation of programmed death-ligand 1 (PD-L1) in the tumor microenvironment (TME). Here we conducted a phase 1 trial (NCT03726515) of CAR T-EGFRvIII cells administered concomitantly with the anti-PD1 (aPD1) monoclonal antibody pembrolizumab in patients with newly diagnosed, EGFRvIII+ glioblastoma (GBM) (n = 7). The primary outcome was safety, and no dose-limiting toxicity was observed. Secondary outcomes included median progression-free survival (5.2 months; 90% confidence interval (CI), 2.9-6.0 months) and median overall survival (11.8 months; 90% CI, 9.2-14.2 months). In exploratory analyses, comparison of the TME in tumors harvested before versus after CAR + aPD1 administration demonstrated substantial evolution of the infiltrating myeloid and T cells, with more exhausted, regulatory, and interferon (IFN)-stimulated T cells at relapse. Our study suggests that the combination of CAR T cells and PD-1 inhibition in GBM is safe and biologically active but, given the lack of efficacy, also indicates a need to consider alternative strategies.

SUV39H1 Ablation Enhances Long-term CAR T Function in Solid Tumors.

Failure of adoptive T-cell therapies in patients with cancer is linked to limited T-cell expansion and persistence, even in memory-prone 41BB-(BBz)-based chimeric antigen receptor (CAR) T cells. We show here that BBz-CAR T-cell stem/memory differentiation and persistence can be enhanced through epigenetic manipulation of the histone 3 lysine 9 trimethylation (H3K9me3) pathway. Inactivation of the H3K9 trimethyltransferase SUV39H1 enhances BBz-CAR T cell long-term persistence, protecting mice against tumor relapses and rechallenges in lung and disseminated solid tumor models up to several months after CAR T-cell infusion. Single-cell transcriptomic (single-cell RNA sequencing) and chromatin opening (single-cell assay for transposase accessible chromatin) analyses of tumor-infiltrating CAR T cells show early reprogramming into self-renewing, stemlike populations with decreased expression of dysfunction genes in all T-cell subpopulations. Therefore, epigenetic manipulation of H3K9 methylation by SUV39H1 optimizes the long-term functional persistence of BBz-CAR T cells, limiting relapses, and providing protection against tumor rechallenges. SIGNIFICANCE: Limited CAR T-cell expansion and persistence hinders therapeutic responses in solid cancer patients. We show that targeting SUV39H1 histone methyltransferase enhances 41BB-based CAR T-cell long-term protection against tumor relapses and rechallenges by increasing stemness/memory differentiation. This opens a safe path to enhancing adoptive cell therapies for solid tumors. See related article by Jain et al., p. 142. This article is featured in Selected Articles from This Issue, p. 5.

Clusterin protects mature dendritic cells from reactive oxygen species mediated cell death.

Dendritic cells (DCs) play a key role in the induction of the adaptive immune response. They capture antigens in peripheral tissues and prime naïve T lymphocytes, triggering the adaptive immune response. In the course of inflammatory processes DCs face stressful conditions including hypoxia, low pH and high concentrations of reactive oxygen species (ROS), among others. How DCs survive under these adverse conditions remain poorly understood. Clusterin is a protein highly expressed by tumors and usually associated with bad prognosis. It promotes cancer cell survival by different mechanisms such as apoptosis inhibition and promotion of autophagy. Here, we show that, upon maturation, human monocyte-derived DCs (MoDCs) up-regulate clusterin expression. Clusterin protects MoDCs from ROS-mediated toxicity, enhancing DC survival and promoting their ability to induce T cell activation. In line with these results, we found that clusterin is expressed by a population of mature LAMP3+ DCs, called mregDCs, but not by immature DCs in human cancer. The expression of clusterin by intratumoral DCs was shown to be associated with a transcriptomic profile indicative of cellular response to stress. These results uncover an important role for clusterin in DC physiology.

Selective control of transposable element expression during T cell exhaustion and anti-PD-1 treatment.

In chronic infections and cancer, T cells are exposed to prolonged antigen stimulation, resulting in loss of function (or exhaustion) and impairment of effective immunological protection. Exhausted T cells are heterogeneous and include early progenitors (Tpex) and terminally exhausted cells (Tex). Here, we used bulk and single-cell transcriptomics to analyze expression of transposable elements (TEs) in subpopulations of mouse and human CD8+ tumor-infiltrating T lymphocytes (TILs). We show that in mice, members of the virus-like murine VL30 TE family (mostly intact, evolutionary young ERV1s) are strongly repressed in terminally exhausted CD8+ T cells in both tumor and viral models of exhaustion. Tpex expression of these VL30s, which are mainly intergenic and transcribed independently of their closest gene neighbors, was driven by Fli1, a transcription factor involved in progression from Tpex to Tex. Immune checkpoint blockade (ICB) in both mice and patients with cancer increased TE expression (including VL30 in mice), demonstrating that TEs may be applicable as ICB response biomarkers. We conclude that expression of TEs is tightly regulated in TILs during establishment of exhaustion and reprogramming by ICB. Analyses of TE expression on single cells and bulk populations open opportunities for understanding immune cell identity and heterogeneity, as well as for defining cellular gene expression signatures and disease biomarkers.

Accelerated subsequent lung cancer after post-operative radiotherapy for breast cancer.

BACKGROUND: Post-operative whole breast radiotherapy for breast cancer (BC) may increase the risk of subsequent lung cancer (LC). The impact of radiotherapy intensification (boost) has not been specifically explored in this context. We investigated the role of radiation modalities on the development of subsequent LC among our patients treated by radiotherapy for localized BC. METHODS: All patients with a diagnosis of LC between 2000 and 2020 with a history of prior localized BC treated by surgery and post-operative radiotherapy were retrospectively reviewed. Primary endpoint was time to first diagnosis of LC after BC treatment with radiotherapy (RT). RESULTS: From 98 patients who developed subsequent LC after primary BC treated with post-operative RT, 38% of patients (n = 37) received an additional RT boost, and 46% (n = 45) received hormonal treatment post radiation. A total of 61% (n = 60) were smokers. With regards to LC characteristics, adenocarcinoma was the most frequent histology (68%, n = 66); 36% (n = 35) harbored at least 1 molecular alteration, 57% (n = 20) of them being amenable to targeted therapy. Median time to first diagnosis of LC was 6 years [1.7-28.4 yrs] in the whole cohort. In the subgroup of patients treated with boost this time was reduced to 4 years [1.8-20.8 years] compared to 8 years for patients without boost [1.7-28.4 yrs] (p = 0.007). Boost, smoking usage, endocrine therapy, and age <50 yrs old at BC radiation remained independent factors associated with shorter time to first diagnosis of LC after BC treatment. DISCUSSION: We report for the first time the potential impact of boost -part of BC radiation treatment- for BC on the risk of subsequent LC. The impact of low dose radiation on lung parenchyma could explain this phenomenon, but the underlying physiopathology is still under investigation. This work highlights the need for clinicians to identify patients at risk of developing faster subsequent thoracic malignancy after BC radiation, for implementing personalized surveillance.

Microbial peptides activate tumour-infiltrating lymphocytes in glioblastoma.

Microbial organisms have key roles in numerous physiological processes in the human body and have recently been shown to modify the response to immune checkpoint inhibitors1,2. Here we aim to address the role of microbial organisms and their potential role in immune reactivity against glioblastoma. We demonstrate that HLA molecules of both glioblastoma tissues and tumour cell lines present bacteria-specific peptides. This finding prompted us to examine whether tumour-infiltrating lymphocytes (TILs) recognize tumour-derived bacterial peptides. Bacterial peptides eluted from HLA class II molecules are recognized by TILs, albeit very weakly. Using an unbiased antigen discovery approach to probe the specificity of a TIL CD4+ T cell clone, we show that it recognizes a broad spectrum of peptides from pathogenic bacteria, commensal gut microbiota and also glioblastoma-related tumour antigens. These peptides were also strongly stimulatory for bulk TILs and peripheral blood memory cells, which then respond to tumour-derived target peptides. Our data hint at how bacterial pathogens and bacterial gut microbiota can be involved in specific immune recognition of tumour antigens. The unbiased identification of microbial target antigens for TILs holds promise for future personalized tumour vaccination approaches.

ETV3 and ETV6 enable monocyte differentiation into dendritic cells by repressing macrophage fate commitment.

In inflamed tissues, monocytes differentiate into macrophages (mo-Macs) or dendritic cells (mo-DCs). In chronic nonresolving inflammation, mo-DCs are major drivers of pathogenic events. Manipulating monocyte differentiation would therefore be an attractive therapeutic strategy. However, how the balance of mo-DC versus mo-Mac fate commitment is regulated is not clear. In the present study, we show that the transcriptional repressors ETV3 and ETV6 control human monocyte differentiation into mo-DCs. ETV3 and ETV6 inhibit interferon (IFN)-stimulated genes; however, their action on monocyte differentiation is independent of IFN signaling. Instead, we find that ETV3 and ETV6 directly repress mo-Mac development by controlling MAFB expression. Mice deficient for Etv6 in monocytes have spontaneous expression of IFN-stimulated genes, confirming that Etv6 regulates IFN responses in vivo. Furthermore, these mice have impaired mo-DC differentiation during inflammation and reduced pathology in an experimental autoimmune encephalomyelitis model. These findings provide information about the molecular control of monocyte fate decision and identify ETV6 as a therapeutic target to redirect monocyte differentiation in inflammatory disorders.

Management of cutaneous toxicities under amivantamab (anti MET and anti EGFR bispecific antibody) in patients with metastatic non-small cell lung cancer harboring EGFR Exon20ins: towards a proactive, multidisciplinary approach.

CONTEXTE: The Epidermal Growth Factor Receptor (EGFR) is mutated in 10-15% of patients with lung adenocarcinoma. At metastatic stage EGFR tyrosine kinase inhibitors (TKIs) are used front line for patients harboring targetable mutations. Novel anti-EGFR therapies are being developed. Amivantamab is a bispecific anti-EGFR and anti-MET antibody with expected skin toxicities. OBJECTIVE: We developed here guidelines for prevention and treatment of cutaneous toxicities under amivantamab according to our experience at Institut Curie. MATERIEL & METHOD: The first patients with metastatic lung cancer harboring EGFR Exon20ins mutation, included in the phase 1 CHRYSALIS trial and cured at Institute Curie from November 1st 2019 until December 31st 2021 were selected for this work. Retrospectively, all cutaneous adverse events were registered and classified according to the CTCAE 6.0 classification, and actions we implemented to minimize and treat these adverse events were collected. We then developed guidelines based on these datas. RESULTS: A total of seven patients started amivantamab as monotherapy. The two most frequent dermatological adverse events were: acneiform rash and paronychia (100 % of patients). Other adverse events presented by the patients were reported: modification of hair growth with hypertrichosis in 50 % of men (n = 1/2) and hirsutism in 80 % of women (n = 4/5); skin abrasion of the scalp in 71 % (n = 5/7); and skin fissure in 57 % (n = 4/7). We recommend first a rigorous inspection of the skin and teguments to determine the risk rate to have dryer skin under treatment; second a prevention of paronychia/acneiform rash/and skin fissures with prophylactic tetracycline, skin moisturizing, and hygienic measures starting at least 14 days before treatment initiation; third a particular attention to the psychological impact of skin toxicities with access to psychological support. CONCLUSION: We propose here guidelines for the management of dermatological toxicities under amivantamab with a multidisciplinary approach for the proactive management of cutaneous toxicities with a focus on preventive actions.

Single-cell RNA-seq-based proteogenomics identifies glioblastoma-specific transposable elements encoding HLA-I-presented peptides.

We analyze transposable elements (TEs) in glioblastoma (GBM) patients using a proteogenomic pipeline that combines single-cell transcriptomics, bulk RNA sequencing (RNA-seq) samples from tumors and healthy-tissue cohorts, and immunopeptidomic samples. We thus identify 370 human leukocyte antigen (HLA)-I-bound peptides encoded by TEs differentially expressed in GBM. Some of the peptides are encoded by repeat sequences from intact open reading frames (ORFs) present in up to several hundred TEs from recent long interspersed nuclear element (LINE)-1, long terminal repeat (LTR), and SVA subfamilies. Other HLA-I-bound peptides are encoded by single copies of TEs from old subfamilies that are expressed recurrently in GBM tumors and not expressed, or very infrequently and at low levels, in healthy tissues (including brain). These peptide-coding, GBM-specific, highly recurrent TEs represent potential tumor-specific targets for cancer immunotherapies.

Aberrant fucosylation enables breast cancer clusterin to interact with dendritic cell-specific ICAM-grabbing non-integrin (DC-SIGN).

Clusterin is a glycoprotein able to mediate different physiological functions such as control of complement activation, promotion of unfolded protein clearance and modulation of cell survival. Clusterin is overexpressed in many types of cancers and a large body of evidence suggests that it promotes carcinogenesis and tumor progression. We have previously described a novel clusterin glycoform present in human semen, but not in serum, highly enriched in terminal fucose motifs. Here we show that human luminal breast cancer (LBC) clusterin also bears terminal fucosylated glycans, conferring clusterin the ability to interact with DC-SIGN, a C-type lectin receptor expressed by myeloid cells. This clusterin glycosylation pattern was absent or diminished in non-involved juxtatumoral tissue, suggesting that fucosylated clusterin might represent a cancer associated glycoform. We also found that DC-SIGN is expressed by luminal breast cancer intratumoral macrophages. Moreover, experiments performed in vitro using semen fucosylated clusterin and monocyte derived macrophages showed that the interaction of semen clusterin with DC-SIGN promoted a proangiogenic profile, characterized by a high production of VEGF, IL-8 and TNF-α. Our results reveal an unexpected complexity on the structure and function of secretory clusterin produced by tumors and suggest that fucosylated clusterin produced by luminal breast cancer cells might play a role in tumor progression by promoting the release of pro-angiogenic factors by intratumoral macrophages.