Expression Of LAG-3 Research Articles

IMMU-12. TRANSLATING COMBINED PD1 AND LAG3 INHIBITION FROM PRECLINICAL MODELS TO PATIENTS WITH REFRACTORY, DNA REPLICATION REPAIR DEFICIENT (RRD) GLIOBLASTOMA: AN IRRDC STUDY

Abstract BACKGROUND AND AIMS RRD-glioblastoma harbour high tumor mutation burden (TMB) and respond to anti-PD1 immune-checkpoint inhibition (ICI). However, not all respond, and the majority progress, highlighting the need for combinatorial therapies for sustained immune-surveillance. METHODS We performed transcriptomic analyses of human RRD-glioblastoma specimens for immune checkpoint expression, and accordingly, tested combined ICI in immunocompetent murine models. Based on these preclinical data, we treated refractory patients using a combination of anti-PD1+anti-LAG3 through single-patient trial/compassionate access. Complimentary immuno-genomic biomarker analyses including circulating tumor DNA (ctDNA) were performed to investigate mechanisms and track responses. RESULTS Human RRD-glioblastoma (n=80) demonstrated high LAG3 expression, providing a strong rationale for therapeutic targeting. We tested combined anti-PD1+anti-LAG3 inhibition in three immunocompetent RRD-glioblastoma murine models. In the anti-PD1-responsive (Nestin-CreMSH2LoxP/LoxP-POLES459F/+) model, anti-PD1+anti-LAG3 resulted in universal tumor response and superior survival to ICI-monotherapy. In the anti-PD1 resistant models (Mlh1-/-/NestinCre+/Trp53LoxP/LoxP and therapy-induced hypermutant ENU/Trp53-/- gliomas), anti-PD1+antiLAG3 improved survival, overcoming the lack of response to ICI-monotherapy. Biologically, high LAG3 expression and immune-exhaustion observed in CD8 T-cells after treatment with anti-PD1 was ablated following the addition of anti-LAG3. Serially transplanted, post-anti-PD1 treated tumors showed response, confirming, in-vivo, that resistance to anti-PD1 could be abrogated by anti-PD1+anti-LAG3. Seven children with refractory RRD-glioblastoma who had progressed after anti-PD1 treatment were treated using anti-PD1+anti-LAG3, resulting in objective radiological responses and prolonged ongoing survival. Tolerability was better than a previous study of combined CTLA4 and PD1 inhibition for similar patients. Paired immuno-genomic tumor analyses, serial blood flow-cytometry, T-cell receptor clonotype, and CSF ctDNA analyses provided novel insights into the mechanisms of immunological invigoration and first-in-human, radiological responses. CONCLUSIONS LAG3 is an effective target in refractory RRD-glioblastoma. Combined inhibition with anti-PD1 inhibition demonstrated radiological response, prolonged survival and manageable toxicities in patients, and unearthered mechanisms of immune-responses. The combination will now be tested in biomarker-driven clinical trials in RRD-glioblastoma and other immune-inflamed solid tumors.

Apolipoprotein A1-encoding recombinant adenovirus remodels cholesterol metabolism in tumors and the tumor microenvironment to inhibit hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a prevalent malignant tumor requiring effective treatments. Oncolytic viruses induce anti-tumor responses but have limited efficacy. Apolipoprotein A1 (ApoA1) inhibits inflammation, modulates immunity, and promotes anti-oxidation. This study aims to construct an oncolytic adenovirus (Ad5)-ApoA1 for superior anti-tumor effects.We analyzed ApoA1 expression in tumors and its prognostic significance using public databases. Subsequently, we engineered a recombinant oncolytic adenovirus Ad5-ApoA1 and assessed its replication and oncolytic efficacy in vitro and in nude mice. The impact of Ad5-ApoA1 on the tumor microenvironment of HCC was evaluated through flow cytometry, transcriptome sequencing, single-cell sequencing, and other methodologies. Additionally, mechanisms of immune microenvironment modulation by Ad5-ApoA1 were explored. ApoA1 expression was down-regulated with HCC progression and significantly positively correlated with the prognosis of HCC patients. Ad5-ApoA1 exhibited robust oncolytic activity but showed no therapeutic effect on nude mice. However, it significantly inhibited HCC growth and prolonged the survival period of both healthy-immune and humanized immune-reconstituted NCG mice. Furthermore, Ad5-ApoA1 significantly promoted the expression of IFN-γ and GzmB in CD8+ T cells while inhibiting the expression of PD-1 and LAG-3. Notably, the cholesterol content in the CD8+ T cells studied was significantly correlated with the expression of PD-1 and LAG-3, with ApoA1 promoting cholesterol efflux and reducing cholesterol levels. Ad5-ApoA1 activates CD8+ T cells by promoting large-scale viral replication. High levels of ApoA1 protein expression promote cholesterol efflux, inhibit CD8+ T cell depletion, and reduce inflammatory factors, ultimately leading to superior therapeutic effects on hepatocellular carcinoma.

LAG-3 Expression, γδ-T cell/MHC-I Interactions and Prognosis in Merkel Cell Carcinoma

Merkel Cell Carcinoma (MCC) is an aggressive cutaneous malignancy with a poor prognosis. One of the major mechanisms of immune evasion in MCC involves downregulation of MHC-I. Anti-PD-1/PD-L1 checkpoint inhibitors (CKIs) have revolutionized treatment for MCC, producing objective responses in ∼50% of patients, and are now standard of care; however, a substantial proportion of patients either fail to respond or develop resistance to CKIs. Given these recent successes, identification of other targetable immune checkpoints in the MCC tumor microenvironment (TME) is of great interest. Additionally, γ-delta (γδ) T cells may play critical roles in the response to MHC-I deficient cancers; therefore, evaluating γδ-T cells as a prognostic biomarker is warranted. We characterized the expression of PD-L1, PD-1, CD3, CD8, LAG-3, MHC-I, and γδ-T cells by IHC in a pre-immunotherapy retrospective cohort of 54 cases of MCC, and quantified expression levels and marker density via HALO. The increased density of LAG-3 and γδ-T cells correlated with other markers of an inflamed TME, with significant positive associations across all six markers (p<.002). Reflective of their putative role in the response to MHC-I suppressed cancers, cases with low HLA-I density showed a trend towards a higher ratio of γδ-T cells:CD3+ T cells (Spearman's r=-0.1582, p=0.21). Importantly, high CD3 density (HR=0.23, p=0.002), LAG-3 density (HR=0.47, p=0.037), γδ-T cell density (HR=0.26, p=0.02), and CD8 density (HR=0.27, p=0.03) showed associations with improved progression-free survival. Conditional tree analysis demonstrated that high CD8 and TCRδ expression were non-significant predictors of improved PFS and OS. Overall, LAG-3 is expressed in MCC infiltrates and is prognostic in pre-immunotherapy MCC, suggesting a potential role for LAG-3 inhibition in MCC. Additionally, CD8 and γδ-T cells may play a critical role in the response to MCC, and γδ-T cell density may represent a novel biomarker in MCC.

Combined Autophagy Inhibition and Dendritic Cell Recruitment Induces Antitumor Immunity and Enhances Immune Checkpoint Blockade Sensitivity in Pancreatic Cancer.

The effect of immune checkpoint inhibitors is extremely limited in patients with pancreatic ductal adenocarcinoma (PDAC) due to the suppressive tumor immune microenvironment (TIME). Autophagy, which has been shown to play a role in anti-tumor immunity, has been proposed as a therapeutic target for PDAC. Here, single-cell RNA-sequencing of autophagy-deficient murine PDAC tumors revealed that autophagy inhibition in cancer cells induced dendritic cell (DC) activation. Analysis of human PDAC tumors substantiated a negative correlation between autophagy and DC activation signatures. Mechanistically, autophagy inhibition increased intracellular accumulation of tumor antigens, which could activate DCs. Administration of chloroquine (CQ), an autophagy inhibitor, in combination with Flt3 ligand (Flt3L)-induced DC infiltration inhibited tumor growth and increased tumor-infiltrating T lymphocytes. However, autophagy inhibition in cancer cells also induced CD8+ T cell exhaustion with high expression of immune checkpoint LAG3. A triple therapy comprising CQ, Flt3L, and an anti-LAG3 antibody markedly reduced tumor growth in orthotopic syngeneic PDAC mouse models. Thus, targeting autophagy in cancer cells and activating DCs sensitizes PDAC tumors to immune checkpoint inhibitor therapy, warranting further development of this treatment approach to overcome immunosuppression in pancreatic cancer.

Comparative analysis of LAG3 antibodies shows differential binding patterns by flow cytometry

BackgroundLAG3 is an immune checkpoint molecule with emerging therapeutic use. Expression of LAG3 is well studied on T cells, but the proportion of LAG3-expressing cells varies greatly by study and its comparative expression between non-T cells is lacking. Methods/objectivesThis study uses flow cytometry to compare surface LAG3 expression between T cells, NK cells, B cells, pDCs and monocytes of healthy donors. This study also compares three monoclonal LAG3 antibodies to a commonly used polyclonal LAG3 antibody on ex vivo and PHA-blasts from healthy donors and LAG3+ and LAG3- cell lines. ResultsLAG3 was most highly expressed on classical and intermediate monocytes (25 % and 32 %, respectively), while LAG3 expression on B cells, NK cells and iNKT cells was negligible. Notably, the polyclonal antibody stained a higher proportion of all cell types than the monoclonal antibodies, which had similar staining patterns to one another. Further study using LAG3+ and LAG3- cell lines showed greater specificity and similar sensitivity of the monoclonal antibody T47–530 than the polyclonal antibody. ConclusionMonocytes may represent an unappreciated source of LAG3 and target of LAG3 checkpoint inhibitors. Furthermore, the discrepancies between monoclonal and polyclonal LAG3 antibodies warrants consideration when designing future studies and interpreting past studies, and may explain discrepancies in the literature.

Abnormal Cellular Populations Shape Thymic Epithelial Tumor Heterogeneity and Anti-Tumor by Blocking Metabolic Interactions in Organoids.

A variety of abnormal epithelial cells and immature and mature immune cells in thymic epithelial tumors (TETs) affect histopathological features, the degree of malignancy, and the response to treatment. Here, gene expression, trajectory inference, and T cell antigen receptor (TCR)-based lineage tracking are profiled in TETs at single-cell resolution. An original subpopulation of KRT14+ progenitor cells with a spindle cell phenotype is shown. An abnormal infiltration of immature T cells with a TCR hyper-rearrangement state is revealed, due to the lack of CCL21+ medullary epithelial cells. For thymic carcinoma, the novel biomarkers of MSLN, CCL20, and SLC1A5 are identified and observed an elevated expression of LAG3 and HAVCR2 in malignant tumorn-infiltrating mature T cells. These common features based on the single-cell populations may inform pathological reclassification of TETs. Meanwhile, it is found that macrophages (MACs) attract thymic tumor cells through the LGALS9-SLC1A5 axis, providing them with glutamine to elicit metabolic reprogramming. This MAC-based metabolic pattern can promote malignancy progression. Additionally, an interactive immune environment in TETs is identified that correlates with the infiltration of abnormal FOXI1+ CFTR- ionocytes. Collectively, the data broaden the knowledge of TET cellular ecosystems, providing a basis for tackling histopathological diagnosis and related treatment.

Single-cell RNA sequencing of pediatric Hodgkin lymphoma to study the inhibition of T cell subtypes.

Pediatric classic Hodgkin lymphoma (cHL) patients have a high survival rate but suffer from severe long-term side effects induced by chemo- and radiotherapy. cHL tumors are characterized by the low fraction (0.1%-10%) of malignant Hodgkin andReed-Sternberg (HRS) cells in the tumor. The HRS cells depend on the surrounding immune cells for survival and growth. This dependence is leveraged by current treatments that target the PD-1/PD-L1 axis in cHL tumors. The development of more targeted therapies that are specific for the tumor and are therefore less toxic for healthy tissue compared with conventional chemotherapy could improve the quality of life of pediatric cHL survivors. Here, we applied single-cell RNA sequencing (scRNA-seq) on isolated HRS cells and the immune cells from the same cHL tumors. Besides TNFRSF8 (CD30), we identified other genes of cell surface proteins that are consistently overexpressed in HRS cells, such as NRXN3 and LRP8, which can potentially be used as alternative targets for antibody-drug conjugates or CAR T cells. Finally, we identified potential interactions by which HRS cells inhibit T cells, among which are the galectin-1/CD69 and HLA-II/LAG3 interactions. RNAscope was used to validate the enrichment of CD69 and LAG3 expression on T cells near HRS cells and indicated large variability of the interaction strength with the corresponding ligands between patients and between tumor tissue regions. In conclusion, this study identifies new potential therapeutic targets for cHL and highlights the importance of studying heterogeneity when identifying therapy targets, specifically those that target tumor-immune cell interactions.

Parkin activates innate immunity and promotes anti-tumor immune responses.

The activation of innate immunity and associated interferon (IFN) signaling have been implicated in cancer, but the regulators are elusive and a link to tumor suppression undetermined. Here, we found that Parkin, an E3 ubiquitin ligase altered in Parkinson's Disease was epigenetically silenced in cancer and its re-expression by clinically approved demethylating therapy stimulated transcription of a potent IFN response in tumor cells. This pathway required Parkin E3 ubiquitin ligase activity, involved the subcellular trafficking and release of the alarmin High Mobility Group Box 1 (HMGB1) and was associated with inhibition of NFκB gene expression. In turn, Parkin-expressing cells released an IFN secretome that upregulated effector and cytotoxic CD8 T cell markers, lowered the expression of immune inhibitory receptors, TIM3 and LAG3, and stimulated high content of the self-renewal/stem cell factor, TCF1. Parkin-induced CD8 T cells selectively accumulated in the microenvironment and inhibited transgenic and syngeneic tumor growth, in vivo. Therefore, Parkin is an epigenetically regulated activator of innate immunity and dual mode tumor suppressor, inhibiting intrinsic tumor traits of metabolism and cell invasion, while simultaneously reinvigorating CD8 T cell functions in the microenvironment.

ImmunoPET imaging of LAG-3 expression in tumor microenvironment with 68Ga-labelled cyclic peptides tracers: from bench to bedside

BackgroundLymphocyte activation gene 3 (LAG-3) has been considered as the next generation of immune checkpoint and a promising prognostic biomarker of immunotherapy. As with programmed cell death protein-1/programmed death-ligand 1...

Exhausted Lag-3+ CD4+ T cells are increased in pediatric Inflammatory Bowel Disease.

T cells are one of the main drivers of inflammatory bowel diseases (IBD). Infliximab (IFX) is used in the treatment of IBD as an anti-inflammatory drug to induce remission by neutralizing TNFα. We determined the individual chemokine/homing receptor and cytokine profile in pediatric IBD patients before and during IFX therapy to identify predictive biomarkers for therapy success. Peripheral blood CD4+ cells from pediatric patients with IBD were immunomagnetically isolated and either directly analyzed by FACS for cell distribution and chemokine/homing receptor expression or evaluated for cytokine production after in-vitro-stimulation. 21 responders (RS) and 21 non-responders (NRS) were recruited. Before IFX therapy, flow cytometry revealed decreased percentages of naïve conventional T cells in pediatric IBD patients. The proportions of CD62-L+ T cells were decreased in both CD and UC therapy responders. The cytokine profile of T cells was highly altered in IBD patients compared to healthy controls (HC). During IFX therapy, the frequencies of conventional memory and regulatory memory T cells expanded in both cohorts. IFX response was marked by a decrease of α4β7+ and IFNγ+ memory T cells in both CD and UC. In contrast, frequencies of Lag-3+ T cells proved to be significantly increased in NRS. These observations were irrespective of the underlying disease. T cells of pediatric IBD patients display an activated and rather Th1/Th17 shifted phenotype The increased expression of the checkpoint molecule Lag-3 on T cells of NRS resembles a more exhausted phenotype than in RS and HC which appeared to be a relevant predictive marker for therapy failure.

Peptide-based PET tracer targeting LAG-3 for evaluating the efficacy of immunotherapy in melanoma

BackgroundLymphocyte activation gene 3 (LAG-3) is expressed on activated immune cells and has emerged as a promising target for immune checkpoints blockade. However, conflicting findings have been reported regarding the...

Start codon variant in LAG3 is associated with decreased LAG-3 expression and increased risk of autoimmune thyroid disease

Autoimmune thyroid disease (AITD) is a common autoimmune disease. In a GWAS meta-analysis of 110,945 cases and 1,084,290 controls, 290 sequence variants at 225 loci are associated with AITD. Of these variants, 115 are previously unreported. Multiomics analysis yields 235 candidate genes outside the MHC-region and the findings highlight the importance of genes involved in T-cell regulation. A rare 5’-UTR variant (rs781745126-T, MAF = 0.13% in Iceland) in LAG3 has the largest effect (OR = 3.42, P = 2.2 × 10−16) and generates a novel start codon for an open reading frame upstream of the canonical protein translation initiation site. rs781745126-T reduces mRNA and surface expression of the inhibitory immune checkpoint LAG-3 co-receptor on activated lymphocyte subsets and halves LAG-3 levels in plasma among heterozygotes. All three homozygous carriers of rs781745126-T have AITD, of whom one also has two other T-cell mediated diseases, that is vitiligo and type 1 diabetes. rs781745126-T associates nominally with vitiligo (OR = 5.1, P = 6.5 × 10−3) but not with type 1 diabetes. Thus, the effect of rs781745126-T is akin to drugs that inhibit LAG-3, which unleash immune responses and can have thyroid dysfunction and vitiligo as adverse events. This illustrates how a multiomics approach can reveal potential drug targets and safety concerns.

Prognostic Role of OX40, LAG-3, TIM-3 and PD-L1 Expression in Bone and Soft Tissue Sarcomas.

Introduction: The current study aims to evaluate the OX40, TIM-3, LAG-3, and PD-L1 targeted pathways in the regulation of T-cell activity in sarcoma patients to determine their relationship with overall survival (OS). Method: This study included one hundred and eleven patients with bone and soft tissue sarcoma diagnosed in two centers between 2010 and 2020. OX40, LAG-3, TIM-3 and PD-L1 expression levels were evaluated immunohistochemically from pathology preparations. Results: PD-L1 staining was detected in tumor cells, OX40, LAG-3, TIM-3 staining was detected in inflammatory cells in tumor tissue. In univariate analysis, no significant relationship was found between OX40, TIM-3, LAG-3, and PD-L1 staining and overall survival (respectively: p = 0.12, p = 0.49, p = 0.31, p = 0.95). When grade and stage at diagnosis, which were found to be significant in univariate analysis, along with OX-40, TIM-3, LAG-3, and PD-L1, were evaluated in multivariate analysis, a positive effect of OX-40 staining on overall survival was determined (p = 0.009). Considering the correlation between PDL-1 and OX40, TIM-3, and LAG-3 staining, a significant positive correlation was found between PDL-1 and TIM-3 and LAG-3 staining (respectively; p = 0.002, p = 0.001). Conclusions: There was no significant relationship between the PDL-1 staining percentage of tumor cells and OX40, TIM-3, and LAG-3 staining in inflammatory cells with the OS of sarcoma patients. However, detecting a significant positive correlation between PDL-1 staining and TIM-3 and LAG-3 staining also holds promise for finding effective targetable combination therapies that can prolong survival in sarcoma patients in the future.

Overexpression of LAG-3: a potential indicator of low immune function in tuberculosis.

Tuberculosis (TB) persists as a global health challenge, with its treatment hampered by the side effects of long-term combination drug therapies and the growing issue of drug resistance. Therefore, the development of novel therapeutic strategies is critical. This study focuses on the role of immune checkpoint molecules (ICs) and functions of CD8+ T cells in the search for new potential targets against TB. We conducted differential expression genes analysis and CD8+ T cell functional gene analysis on 92 TB samples and 61 healthy individual (HI) samples from TB database GSE83456, which contains data on 34,603 genes. The GSE54992 dataset was used to validated the findings. Additionally, a cluster analysis on single-cell data from primates infected with mycobacterium tuberculosis and those vaccinated with BCG was performed. The overexpression of LAG-3 gene was found as a potentially important characteristic of both pulmonary TB (PTB) and extrapulmonary TB (EPTB). Further correlation analysis showed that LAG-3 gene was correlated with GZMB, perforin, IL-2 and IL-12. A significant temporal and spatial variation in LAG-3 expression was observed in T cells and macrophages during TB infection and after BCG vaccination. LAG-3 was overexpressed in TB samples. Targeting LAG-3 may represent a potential therapeutic target for tuberculosis.

Stringent monitoring can decrease mortality of immune checkpoint inhibitor induced cardiotoxicity.

Immune checkpoint inhibitor (ICI)-induced myocarditis is a rare immune-related adverse event (irAE) with a fatality rate of 40%-46%. However, irMyocarditis can be asymptomatic. Thus, improved monitoring, detection and therapy are needed. This study aims to generate knowledge on pathogenesis and assess outcomes in cancer centers with intensified patient management. Patients with cardiac irAEs from the SERIO registry (www.serio-registry.org) were analyzed for demographics, ICI-related information (type of ICI, therapy line, combination with other drugs, onset of irAE, and tumor response), examination results, irAE treatment and outcome, as well as oncological endpoints. Cardiac biopsies of irMyocarditis cases (n = 12) were analyzed by Nanostring and compared to healthy heart muscle (n = 5) and longitudinal blood sampling was performed for immunophenotyping of irMyocarditis-patients (n = 4 baseline and n = 8 during irAE) in comparison to patients without toxicity under ICI-therapy (n = 4 baseline and n = 7 during ICI-therapy) using flow cytometry. A total of 51 patients with 53 cardiac irAEs induced by 4 different ICIs (anti-PD1, anti-PD-L1, anti-CTLA4) were included from 12 centers in 3 countries. Altogether, 83.0% of cardiac irAEs were graded as severe or life-threatening, and 11.3% were fatal (6/53). Thus, in centers with established consequent troponin monitoring, work-up upon the rise in troponin and consequent treatment of irMyocarditis with corticosteroids and -if required-second-line therapy mortality rate is much lower than previously reported. The median time to irMyocarditis was 36 days (range 4-1,074 days) after ICI initiation, whereas other cardiotoxicities, e.g. asystolia or myocardiopathy, occurred much later. The cytokine-mediated signaling pathway was differentially regulated in myocardial biopsies as compared to healthy heart based on enrichment Gene Ontology analysis. Additionally, longitudinal peripheral blood mononuclear cell (PBMC) samples from irMyocarditis-patients indicated ICI-driven enhanced CD4+ Treg cells and reduced CD4+ T cells. Immunophenotypes, particularly effector memory T cells of irMyocarditis-patients differed from those of ICI-treated patients without side effects. LAG3 expression on T cells and PD-L1 expression on dendritic cells could serve as predictive indicators for the development of irMyocarditis. Interestingly, our cohort shows a very low mortality rate of irMyocarditis-patients. Our data indicate so far unknown local and systemic immunological patterns in cardiotoxicity.

Expression and Prognostic Significance of LAG-3, TIGIT, VISTA, and IDO1 in Endometrial Serous Carcinoma

Endometrial serous carcinoma (ESC) is an uncommon, aggressive type of endometrial cancer. While immune checkpoint blockade has emerged as a promising treatment option for endometrial carcinomas, research on the expression of immune checkpoints that could serve as prospective immunotherapy targets in ESC is limited. We examined the prevalence and prognostic value of LAG-3, TIGIT, VISTA, and IDO1 in 94 cases of ESC and correlated their expression with CD8+ and FOXP3+ tumor infiltrating lymphocytes (TIL). We observed a positive correlation between LAG-3, TIGIT and VISTA expressed on immune cells, and between these markers and CD8+ and FOXP3+ TIL density. In Kaplan-Meier survival analysis, tumors with high levels of LAG-3 and TIGIT expression had better progression free survival (PFS) and overall survival (OS) than those with lower levels of expression (LAG-3: PFS, p=0.03, OS, p=0.04; TIGIT: PFS, p=0.01, OS, p=0.009). In multivariate analysis, only high TIGIT expression was of independent prognostic value for better overall survival. VISTA expression in immune or tumor cells, and IDO1 expression in tumor cells, did not show a significant association with survival. Our data indicate that LAG-3, TIGIT, and VISTA immune checkpoints have roles in the microenvironment of ESC, and their expression patterns highlight the complex interactions among the different components of this system. High levels of these markers, together with high CD8+ TIL, suggests the potential immunogenicity of a subset of these tumors. Further studies are needed to elucidate the roles of various immune components in the ESC microenvironment and their association with intrinsic tumor properties.

Regulatory and memory T lymphocytes infiltrating prostate tumors predict long term clinical outcomes.

The localization, density but mostly the phenotype of tumor infiltrating lymphocytes (TIL) provide important information on the initial interaction between the host immune system and the tumor. Our objective was to assess the prognostic significance of T (CD3+), T regulatory (Treg) (FoxP3+) and T memory (Tmem) (CD45RO+) infiltrating lymphocytes and of genes associated with TIL in prostate cancer (PCa). Immunohistochemistry (IHC) was used to assess the infiltration of CD3+, FoxP3+ and CD45RO+ cells in the tumor area, tumor margin and adjacent normal-like epithelium of a series of 98 PCa samples with long clinical follow-up. Expression of a panel of 31 TIL-associated genes was analyzed by Taqman Low-Density Array (TLDA) technology in another series of 50 tumors with long clinical follow-up. Kaplan-Meier and Cox proportional hazards regression analyses were performed to determine association of these markers with biochemical recurrence (BCR), need for definitive androgen deprivation therapy (ADT) or lethal PCa. TIL subtypes were present at different densities in the tumor, tumor margin and adjacent normal-like epithelium, but their density and phenotype in the tumor area were the most predictive of clinical outcomes. In multivariate analyses, a high density of Treg (high FoxP3+/CD3+ cell ratio) predicted a higher risk for need of definitive ADT (HR=7.69, p=0.001) and lethal PCa (HR=4.37, p=0.04). Conversely, a high density of Tmem (high CD45RO+/CD3+ cell ratio) predicted a reduced risk of lethal PCa (HR=0.06, p=0.04). TLDA analyses showed that a high expression of FoxP3 was associated with a higher risk of lethal PCa (HR=5.26, p=0.02). Expression of CTLA-4, PD-1, TIM-3 and LAG-3 were correlated with that of FoxP3. Amongst these, only a high expression of TIM-3 was associated with a significant higher risk for definitive ADT in univariate Cox regression analysis (HR=3.11, p=0.01). These results show that the proportion of Treg and Tmem found within the tumor area is a strong and independent predictor of late systemic progression of PCa. Our results also suggest that inhibition of TIM-3 might be a potential approach to counter the immunosuppressive functions of Treg in order to improve the anti-tumor immune response against PCa.

TRICK-MCC: A proof-of-concept, investigator-initiated study of combination therapy with anti–PD-1, anti–LAG-3, and anti–TIM-3 in participants with advanced or metastatic PD-(L)1 refractory Merkel cell carcinoma.

TPS9618 Background: Merkel cell carcinoma (MCC) is an aggressive and highly immunogenic skin cancer often associated with the Merkel cell polyomavirus (MCPyV). Immune checkpoint inhibition (ICI) via PD-(L)1 blockade can promote durable responses among patients with metastatic MCC, yet &gt;50% of MCC patients experience disease progression. There is an unmet need for effective treatment options for these patients. One possible strategy to overcome primary and secondary resistance in PD-(L)1 refractory MCC is concurrent targeting of multiple immune checkpoints to facilitate reversal of chronic T cell exhaustion. Based on our preliminary data revealing high expression of PD-1, LAG-3 and TIM-3 on MCC-specific CD8 T cells, which appear to increase upon clinical disease progression in the context of treatment with PD-(L)1 blockade, we hypothesize that concurrent blockade of PD-1, LAG-3 and TIM-3 will overcome immune evasion in patients with PD-(L) refractory MCC. Methods: TRICK-MCC (Triple Immune Checkpoint Inhibition in MCC) is an investigator initiated, Phase 2 clinical trial investigating concurrent treatment with anti-PD-1 (retifanlimab), anti-LAG3 (INCAGN02385) and anti-TIM-3 (INCAGN02390) in patients with advanced/metastatic MCC that has progressed after treatment with anti-PD-(L)1. Target enrollment is 20 patients total, with 5 patients enrolled as of Jan 2024. Patients will receive anti-PD-1 q4w and anti-TIM-3 and LAG-3 q2w for up to 24 weeks (Induction Phase) followed by all drugs q6w (Maintenance Phase). Treatment will end 2 years after starting the study drugs, or upon disease progression, unacceptable toxicity, or study withdrawal. Primary objective is objective response rate (ORR). Secondary objectives are duration of response, progression free survival, overall survival, and incidence and severity of adverse events. Interim analysis will be done after 10 patients have been enrolled and followed sufficiently long to assess ORR. An observed ORR of 25%will be considered as clinically meaningful in this population with no reliable standard treatments. Serial tumor biopsies and blood samples will be obtained in all patients, unless deemed unsafe or not feasible. Planned correlative studies aim to better characterize the prevalence and significance of cancer-specific T cell exhaustion (through rigorous study of MCPyV-specific T cells), the immunologic effects of triple ICI, and alternative mechanisms of PD-(L)1 resistance beyond T cell exhaustion in PD-(L)1 resistant tumors. We hope to gain insights that are broadly applicable to solid tumor immunotherapy. Clinical trial information: NCT06056895 .

Uncovering actionable genetic alterations and immune predictive biomarkers for anal squamous cell carcinomas in the era of immunotherapy: PD-L1 and beyond.

3518 Background: Squamous cell carcinoma of the anal canal (SCAC) is a rare cancer with limited treatments. Immune checkpoint inhibitors (ICIs) use is routine for recurrent/refractory disease, but predictive biomarkers remain elusive. We analyzed the largest dataset of SCAC to date, focusing on PD-L1 expression. Methods: Next-generation sequencing of DNA (592 genes or WES) and RNA (WTS) was tested at Caris Life Sciences (Phoenix, AZ). PD-L1 was tested by immunohistochemistry (IHC) (SP142) and grouped as high (2+ and ≥5%), low (1-2 and 1-5%), and negative (0) CPS. dMMR/MSI-H was tested by IHC/NGS and tumor mutation burden (TMB)-High was defined as &gt;10 mt/MB. RNA expression data was used to estimate the tumor microenvironment (TME) using QuantiSEQ. RNA signatures predictive of ICI response (interferon gamma [IFNγ]; T-cell inflamed signature [TIS]) were tested. X2/Fisher-Exact was used with significance shown as P-value adjusted for multiple comparisons (Q&lt;0.05). Real-world overall survival (rwOS) was from insurance claims and calculated from tissue collection to last contact; time-on-treatment (TOT) was from start to finish of ICI. Results: Of 1242 SCAC samples, 64.3% (798) expressed PD-L1, 41.7% (518) showed high PD-L1 expression, 1.2% were dMMR/MSI-H and 14.5% were TMB-high. TMB-H trended higher in PD-L1 low vs PD-L1 negative (16.3% vs 10.2%, p=0.036). No trend was seen for dMMR/MSI-H. Mutations in PIK3CA (38.3% vs 21.7%) and CASP8(5.3% vs 0.3%) were significantly higher in PD-L1 high vs negative. Similar trends were seen in NF1 (2.4% vs 0.4%) and ARID1A (2.7% vs 0.6%). The opposite was noted for JAK2 (0% vs 2.6%), BAP1 (1.1% vs 3.6%) mutations, and FGFR3 amplifications (0% vs 2.2%). For PD-L1 high vs negative, infiltration of Tregs, M1 macrophages, neutrophils, CD8+ cells, and cancer-associated fibroblasts decreased with PD-L1 expression (fold change [FC]: 0.67-0.80, Q&lt;0.05). Expression of immune-oncology (IO) markers IDO1, PDCD1, IFNG, CD274, HVACR2, CTLA4, LAG3, CD80, CD86 and PDCD1LG2 decreased with PD-L1 expression (FC:0.35-0.73, Q&lt;0.05). Similarly, TIS and IFNg scores decreased with PD-L1 IHC (Q&lt;0.05). In 316 SCAC patients treated with ICIs, PD-L1 high had longer TOT compared to PD-L1 negative (N=168 vs 80, 5.5m vs 2.9m, HR 0.758, 95% CI 0.579 to 0.992, p=0.044) while PD-L1 low (N=68) showed a TOT in between (3.2m) but not significantly different compared to high or negative. No differences in rwOS were observed. Conclusions: PD-L1 is expressed in over 50% of SCACs, while dMMR/MSI-H is rare. High PD-L1-expressing tumors have higher PIK3CAand CASP8 mutations and overexpress IO markers, are inflamed, and have prolonged treatment times with ICIs. This is the largest study to date reporting SCAC genomic profiles and identifies the utility of PD-L1 as a predictive biomarker of IO efficacy. This discovery needs to be confirmed in prospective trials.

Human leukocyte antigen (HLA) class I expression on Hodgkin-Reed-Sternberg cells is an EBV-independent major determinant of microenvironment composition in classic Hodgkin lymphoma.

Hodgkin-Reed-Sternberg cells (HRSCs) in classic Hodgkin Lymphoma (HL) frequently lack expression of human leukocyte antigen class I (HLA-I), considered to hamper activation of cytotoxic T cells in the tumor microenvironment (TME). Here, we demonstrate HLA-I expression on HRSCs to be a strong determinant of TME composition whereas expression of HLA-II was associated with only minor differential gene expression in the TME. In HLA-I-positive HL the HRSC content and expression of CCL17/TARC in HRSCs are low, independent of the presence of Epstein-Barr virus in HRSCs. Additionally, HLA-I-positive HL shows a high content of CD8+ cytotoxic T cells. However, an increased expression of the inhibitory immune checkpoint LAG3 on CD8+ T cells in close proximity to HRSCs is observed. Suggesting interference with cytotoxic activity, we observed an absence of clonally expanded T cells in the TME. While HLA-I-positive HL is not associated with an unfavorable clinical course in our cohorts, they share features with the recently described H2 subtype of HL. Given the major differences in TME composition, immune checkpoint inhibitors may differ in their mechanism of action in HLA-I-positive compared to HLA-I-negative HL.