RICTOR amplification is associated with Rictor membrane staining and does not correlate with PD-L1 expression in lung squamous cell carcinoma.

RICTOR gene, which encodes the scaffold protein of mTORC2, can be amplified in various tumor types, including squamous cell carcinoma (SCC) of the lung. RICTOR amplification can lead to hyperactivation of mTORC2 and may serve as a targetable genetic alteration, including in lung SCC patients with no PD-L1 expression who are not expected to benefit from immune checkpoint inhibitor therapy. This study aimed to compare RICTOR amplification detected by fluorescence in situ hybridization (FISH) with Rictor and PD-L1 protein expression detected by immunohistochemistry (IHC) in SCC of the lung. The study was complemented by analysis of the publicly available Lung Squamous Cell Carcinoma (TCGA, Firehose legacy) dataset. RICTOR amplification was observed in 20% of our cases and 16% of the lung SCC cases of the TCGA dataset. Rictor and PD-L1 expression was seen in 74% and 44% of the cases, respectively. Rictor IHC showed two staining patterns: membrane staining (16% of the cases) and cytoplasmic staining (58% of the cases). Rictor membrane staining predicted RICTOR amplification as detected by FISH with high specificity (95%) and sensitivity (70%). We did not find any correlation between RICTOR amplification and PD-L1 expression; RICTOR amplification was detected in 18% and 26% of PD-L1 positive and negative cases, respectively. The TCGA dataset analysis showed similar results; RICTOR copy number correlated with Rictor mRNA and protein expression but showed no association with PD-L1 mRNA and protein expression. In conclusion, the correlation between RICTOR amplification and Rictor membrane staining suggests that the latter can potentially be used as a surrogate marker to identify lung SCC cases with RICTOR amplification. Since a significant proportion of PD-L1 negative SCC cases harbor RICTOR amplification, analyzing PD-L1 negative tumors by RICTOR FISH or Rictor IHC can help select patients who may benefit from mTORC2 inhibitor therapy.

Cyclodextrin encapsulation enabling the anticancer repositioning of disulfiram: Preparation, analytical and in vitro biological characterization of the inclusion complexes.

Drug repositioning is a high-priority and feasible strategy in the field of oncology research, where the unmet medical needs are continuously unbalanced. Disulfiram is a potential non-chemotherapeutic, adjuvant anticancer agent. However, the clinical translation is limited by the drug's poor bioavailability. Therefore, the molecular encapsulation of disulfiram with cyclodextrins is evaluated to enhance the solubility and stability of the drug. The present work describes for the first time the complexation of disulfiram with randomly methylated-ß-cyclodextrin. A parallel analytical andin vitrobiological comparison of disulfiram inclusion complexes with hydroxypropyl-ß-cyclodextrin, randomly methylated-ß-cyclodextrin and sulfobutylether-ß-cyclodextrin is conducted. A significant drug solubility enhancement by about 1000-folds and fast dissolution in 1 min is demonstrated. Thein vitrodissolution-permeation studies and proliferation assays demonstrate the solubility-dependent efficacy of the drug. Throughout the different cancer cell lines' characteristics and disulfiram unspecific antitumoral activity, the inhibitory efficacy of the cyclodextrin encapsulated drug on melanoma (IC50 about 100 nM) and on glioblastoma (IC50 about 7000 nM) cell lines differ by a magnitude. This pre-formulation screening experiment serves as a proof of concept of using cyclodextrin encapsulation as a platform tool for further drug delivery development in repositioning areas.

mTOR hyperactivity and RICTOR amplification as targets for personalized treatments in malignancies.

The increasing knowledge of molecular alterations in malignancies, including mutations and regulatory failures in the mTOR (mechanistic target of rapamycin) signaling pathway, highlights the importance of mTOR hyperactivity as a validated target in common and rare malignancies. This review summarises recent findings on the characterization and prognostic role of mTOR kinase complexes (mTORC1 and mTORC2) activity regarding differences in their function, structure, regulatory mechanisms, and inhibitor sensitivity. We have recently identified new tumor types with RICTOR (rapamycin-insensitive companion of mTOR) amplification and associated mTORC2 hyperactivity as useful potential targets for developing targeted therapies in lung cancer and other newly described malignancies. The activity of mTOR complexes is recommended to be assessed and considered in cancers before mTOR inhibitor therapy, as current first-generation mTOR inhibitors (rapamycin and analogs) can be ineffective in the presence of mTORC2 hyperactivity. We have introduced and proposed a marker panel to determine tissue characteristics of mTOR activity in biopsy specimens, patient materials, and cell lines. Ongoing phase trials of new inhibitors and combination therapies are promising in advanced-stage patients selected by genetic alterations, molecular markers, and/or protein expression changes in the mTOR signaling pathway. Hopefully, the summarized results, our findings, and the suggested characterization of mTOR activity will support therapeutic decisions.

Tumorigenic role of tacrolimus through mTORC1/C2 activation in post-transplant renal cell carcinomas.

BACKGROUND: Kidney transplant recipients (KTRs) face an increased risk of renal cell carcinoma (RCC), in which the immunosuppressive regimen plays an important role. This study aimed to identify intracellular signalling alterations associated with post-transplant (post-tx) tumour formation. METHODS: Expression of mTOR-related proteins were analysed in kidneys obtained from end-stage renal disease (ESRD) patients and RCCs developed in KTRs or non-transplant patients. The effects of tacrolimus (TAC) and rapamycin (RAPA) on mTOR activity, proliferation, and tumour growth were investigated through different in vitro and in vivo experiments. RESULTS: Elevated mTORC1/C2 activity was observed in post-tx RCCs and in kidneys of TAC-treated ESRD patients. In vitro experiments demonstrated that TAC increases mTOR activity in a normal tubular epithelial cell line and in the investigated RCC cell lines, moreover, promotes the proliferation of some RCC cell line. In vivo, TAC elevated mTORC1/C2 activity in ischaemic kidneys of mice and enhanced tumour growth in xenograft model. CONCLUSIONS: We observed significantly increased mTOR activity in ischaemic kidneys and post-tx RCCs, which highlights involvement of mTOR pathway both in the healing or fibrotic processes of kidney and in tumorigenesis. TAC-treatment further augmented the already elevated mTOR activity of injured kidney, potentially contributing to tumorigenesis during immunosuppression.

Rictor-A Mediator of Progression and Metastasis in Lung Cancer.

Lung carcinoma is one of the most common cancer types for both men and women. Despite recent breakthroughs in targeted therapy and immunotherapy, it is characterized by a high metastatic rate, which can significantly affect quality of life and prognosis. Rictor (encoded by the RICTOR gene) is known as a scaffold protein for the multiprotein complex mTORC2. Among its diverse roles in regulating essential cellular functions, mTORC2 also facilitates epithelial-mesenchymal transition and metastasis formation. Amplification of the RICTOR gene and subsequent overexpression of the Rictor protein can result in the activation of mTORC2, which promotes cell survival and migration. Based on recent studies, RICTOR amplification or Rictor overexpression can serve as a marker for mTORC2 activation, which in turn provides a promising druggable target. Although selective inhibitors of Rictor and the Rictor-mTOR association are only in a preclinical phase, they seem to be potent novel approaches to reduce tumor cell migration and metastasis formation. Here, we summarize recent advances that support an important role for Rictor and mTORC2 as potential therapeutic targets in the treatment of lung cancer. This is a traditional (narrative) review based on Pubmed and Google Scholar searches for the following keywords: Rictor, RICTOR amplification, mTORC2, Rictor complexes, lung cancer, metastasis, progression, mTOR inhibitors.

Cell-free ascites from ovarian cancer patients induces Warburg metabolism and cell proliferation through TGFß-ERK signaling.

Ascites plays a key role in supporting the metastatic potential of ovarian cancer cells. Shear stress and carry-over of cancer cells by ascites flow support carcinogenesis and metastasis formation. In addition, soluble factors may participate in the procarcinogenic effects of ascites in ovarian cancer. This study aimed to determine the biological effects of cell-free ascites on carcinogenesis in ovarian cancer cells. Cell-free ascites from ovarian cancer patients (ASC) non-selectively induced cell proliferation in multiple models of ovarian cancer and untransformed primary human dermal fibroblasts. Furthermore, ASC induced a Warburg-type rearrangement of cellular metabolism in A2780 ovarian cancer cells characterized by increases in cellular oxygen consumption and glycolytic flux; increases in glycolytic flux were dominant. ASC induced mitochondrial uncoupling and fundamentally reduced fatty acid oxidation. Ascites-elicited effects were uniform among ascites specimens. ASC-elicited transcriptomic changes in A2780 ovarian cancer cells included induction of the TGFß-ERK/MEK pathway, which plays a key role in inducing cell proliferation and oncometabolism. ASC-induced gene expression changes, as well as the overexpression of members of the TGFß signaling system, were associated with poor survival in ovarian cancer patients. We provided evidence that the activation of the autocrine/paracrine of TGFß signaling system may be present in bladder urothelial carcinoma and stomach adenocarcinoma. Database analysis suggests that the TGFß system may feed forward bladder urothelial carcinoma and stomach adenocarcinoma. Soluble components of ASC support the progression of ovarian cancer. These results suggest that reducing ascites production may play an essential role in the treatment of ovarian cancer by inhibiting the progression and reducing the severity of the disease.

Novel RICTOR amplification harbouring entities: FISH validation of RICTOR amplification in tumour tissue after next-generation sequencing.

Alterations in mTOR signalling molecules, including RICTOR amplification, have been previously described in many cancers, particularly associated with poor prognosis. In this study, RICTOR copy number variation (CNV) results of diagnostic next-generation sequencing (NGS) were analysed in 420 various human malignant tissues. RICTOR amplification was tested by Droplet Digital PCR (ddPCR) and validated using the "gold standard" fluorescence in situ hybridisation (FISH). Additionally, the consequences of Rictor protein expression were also studied by immunohistochemistry. RICTOR amplification was presumed in 37 cases with CNV ≥ 3 by NGS, among these, 16 cases (16/420; 3.8%) could be validated by FISH, however, ddPCR confirmed only 11 RICTOR-amplified cases with lower sensitivity. Based on these, neither NGS nor ddPCR could replace traditional FISH in proof of RICTOR amplification. However, NGS could be beneficial to highlight potential RICTOR-amplified cases. The obtained results of the 14 different tumour types with FISH-validated RICTOR amplification demonstrate the importance of RICTOR amplification in a broad spectrum of tumours. The newly described RICTOR-amplified entities could initiate further collaborative studies with larger cohorts to analyse the prevalence of RICTOR amplification in rare diseases. Finally, our and further work could help to improve and expand future therapeutic opportunities for mTOR-targeted therapies.

Novel Metabolic Approaches Targeting Cancer Cells.

Metabolic reprogramming is one of the main hallmarks of cancer [...].

Dynamic Interplay in Tumor Ecosystems: Communication between Hepatoma Cells and Fibroblasts.

Tumors are intricate ecosystems where cancer cells and non-malignant stromal cells, including cancer-associated fibroblasts (CAFs), engage in complex communication. In this study, we investigated the interaction between poorly (HLE) and well-differentiated (HuH7) hepatoma cells and LX2 fibroblasts. We explored various communication channels, including soluble factors, metabolites, extracellular vesicles (EVs), and miRNAs. Co-culture with HLE cells induced LX2 to produce higher levels of laminin ß1, type IV collagen, and CD44, with pronounced syndecan-1 shedding. Conversely, in HuH7/LX2 co-culture, fibronectin, thrombospondin-1, type IV collagen, and cell surface syndecan-1 were dominant matrix components. Integrins α6ß4 and α6ß1 were upregulated in HLE, while α5ß1 and αVß1 were increased in HuH7. HLE-stimulated LX2 produced excess MMP-2 and 9, whereas HuH7-stimulated LX2 produced excess MMP-1. LX2 activated MAPK and Wnt signaling in hepatoma cells, and conversely, hepatoma-derived EVs upregulated MAPK and Wnt in LX2 cells. LX2-derived EVs induced over tenfold upregulation of SPOCK1/testican-1 in hepatoma EV cargo. We also identified liver cancer-specific miRNAs in hepatoma EVs, with potential implications for early diagnosis. In summary, our study reveals tumor type-dependent communication between hepatoma cells and fibroblasts, shedding light on potential implications for tumor progression. However, the clinical relevance of liver cancer-specific miRNAs requires further investigation.

Antimicrobial Peptides (AMP) in the Cell-Free Culture Media of Xenorhabdus budapestensis and X. szentirmaii Exert Anti-Protist Activity against Eukaryotic Vertebrate Pathogens including Histomonas meleagridis and Leishmania donovani Species.

Anti-microbial peptides provide a powerful toolkit for combating multidrug resistance. Combating eukaryotic pathogens is complicated because the intracellular drug targets in the eukaryotic pathogen are frequently homologs of cellular structures of vital importance in the host organism. The entomopathogenic bacteria (EPB), symbionts of entomopathogenic-nematode species, release a series of non-ribosomal templated anti-microbial peptides. Some may be potential drug candidates. The ability of an entomopathogenic-nematode/entomopathogenic bacterium symbiotic complex to survive in a given polyxenic milieu is a coevolutionary product. This explains that those gene complexes that are responsible for the biosynthesis of different non-ribosomal templated anti-microbial protective peptides (including those that are potently capable of inactivating the protist mammalian pathogen Leishmania donovanii and the gallinaceous bird pathogen Histomonas meleagridis) are co-regulated. Our approach is based on comparative anti-microbial bioassays of the culture media of the wild-type and regulatory mutant strains. We concluded that Xenorhabdus budapestensis and X. szentirmaii are excellent sources of non-ribosomal templated anti-microbial peptides that are efficient antagonists of the mentioned pathogens. Data on selective cytotoxicity of different cell-free culture media encourage us to forecast that the recently discovered "easy-PACId" research strategy is suitable for constructing entomopathogenic-bacterium (EPB) strains producing and releasing single, harmless, non-ribosomal templated anti-microbial peptides with considerable drug, (probiotic)-candidate potential.

[he importance of mTOR hyperactivity and RICTOR amplification, and the associated targeted therapy possibilities in malignant tumours]. / Az mTOR-hiperaktivitás és a RICTORamplifikáció jelentosége, és az ezzel összefüggo célzott terápiás lehetoségek rosszindulatú daganatokban.

Failures of anti-tumour therapies and drug resistance initiate difficulties in cancer treatments often caused by alterations in signalling network activity, including PI3K/Akt/mTOR hyperactivity due to oncogenic mutations. In this review, we summarise the relevance of mTOR (mechanistic target of rapamycin) dysregulation identified decades ago, which is now known to be characteristic of many tumours. In this context, we present differences in activity, function and testability of mTOR kinase complexes (mTORC1 and mTORC2) differing in structure, regulatory mechanisms and inhibitor sensitivity. We highlight that genetic alterations, including RICTOR amplification and associated mTOR hyperactivity, are relevant in targeted therapy development. It is recommended to investigate mTOR profile activity in patients for whom mTOR inhibitor therapies are considered since the current first-generation mTOR inhibitors (rapamycin and analogues) may be ineffective in case of mTORC2 hyperactivity. Ongoing phase trials of new inhibitors and combination therapies are promising in advanced stage patients selected by molecular markers.

[Effects of 3D tissue structure on drug sensitivity - 3D bioprinted tissue mimetic structures in cancer research]. / 3D szöveti szerkezet hatása a gyógyszerérzékenységre ­ 3D bionyomtatott "szövetmodellek" a daganatkutatásban.

The issues surrounding the cost effectiveness of drug development and the ethical concerns associated with animal testing, emphasise the necessity for innovative in vitro models that allow enhanced pre-selection. Therefore, we aim to create 3D bioprinted tissue mimetic structures (TMS) utilizing various human cancer cell lines. We have generated TMSs from human tumour cell lines (breast, kidney, glioma), with detailed characterisation of the ZR75.1 cell line. In this study, the tissue heterogeneity, the growth rate, and the drug sensitivity of different in vitro and in vivo models were compared. Tissue formation occurs within the TMS after one week, with a tissue heterogeneity similar to in vivo growing tumours. Moreover, TMSs exhibit similar drug sensitivity to that observed in vivo. In summary, the established 3D bioprinted TMSs represent an advanced in vitro model, which can contribute to achieve a more effective and ethical drug development process in the field of oncology.

BMP-induced non-canonical signaling is upregulated during autophagy-mediated regeneration in inflamed mesothelial cells.

Previously, we showed that after Freund's adjuvant-induced peritonitis, rat mesothelial cells regain their epithelial phenotype through mesenchymal-epithelial transition (MET) accompanied by autophagy. Since bone morphogenetic proteins (BMPs) are well-known MET-inducers, we were interested in the potential expression of BMPs and BMP-induced pathways. Although mesothelial cells expressed lower amounts of BMP7, its level in the peritoneal cavity and mesothelial synthesis of BMP4 were significantly increased during inflammation. BMPR1A and BMPR2 were also significantly expressed. Expression of transforming growth factor beta-activated kinase (TAK1) and c-Jun NH2-terminal kinases (JNK1-JNK2) were more intense than that of phosphorylated Mothers Against Decapentaplegic homolog 1/5 (p-SMAD1/5), confirming that the non-canonical pathway of BMPs prevailed in our model. JNK signaling through B-cell lymphoma-2 (Bcl-2) can contribute to Beclin-1 activation. We demonstrated that TAK1-JNK-Bcl-2 signaling was upregulated simultaneously with the autophagy-mediated regeneration. A further goal of our study was to prove the regenerative role of autophagy after inflammation. We used a specific inhibitor, bafilomycin A1 (BafA1), and found that BafA1 treatment decreased the expression of microtubule-associated protein 1A/1B-light chain 3 (LC3B) and resulted in morphological signs of cell death in inflamed mesothelial cells indicating that if autophagy is arrested, regeneration turns into cell death and consequently, mesothelial cells die.

Corrigendum: SPOCK1 promotes the development of hepatocellular carcinoma.

[This corrects the article DOI: 10.3389/fonc.2022.819883.].

Clinical, pharmacological, and formulation evaluation of disulfiram in the treatment of glioblastoma - a systematic literature review.

INTRODUCTION: Glioblastoma (GB) is one of the most challenging central nervous system (CNS) tumors in treatment options and response, urging the development of novel management strategies. The anti-alcoholism drug, disulfiram (DS), has a potential anticancer activity, and its complex mechanism of action is assumed to be well exploited against the heterogeneous GB. AREA COVERED: Through a systematic literature review about repositioning DS to GB treatment, an evaluation of the clinical, pharmacological, and formulation strategies is provided to specify the challenges of drug delivery and thus to advance its clinical translation. From six databases, 35 articles were selected, including case report (1); clinical trials (3); original articles mainly representing in vitro and preclinical pharmacological data, and 10 dealing with technological approaches. EXPERT OPINION: The repositioning of DS in GB treatment is facing drug and tumor-associated limitations due to the oral drug's low bioavailability, unwanted metabolism, and inefficient delivery to brain-tumor tissue. Development strategies using molecular encapsulation of DS and the parenteral dosage forms improve the anticancer pharmacology of the drug. The development of optimized drug delivery systems (DDS) shows promise for the clinical translation of DS into GB adjuvant therapy.

3D bioprinting and the revolution in experimental cancer model systems-A review of developing new models and experiences with in vitro 3D bioprinted breast cancer tissue-mimetic structures.

Growing evidence propagates those alternative technologies (relevant human cell-based-e.g., organ-on-chips or biofabricated models-or artificial intelligence-combined technologies) that could help in vitro test and predict human response and toxicity in medical research more accurately. In vitro disease model developments have great efforts to create and serve the need of reducing and replacing animal experiments and establishing human cell-based in vitro test systems for research use, innovations, and drug tests. We need human cell-based test systems for disease models and experimental cancer research; therefore, in vitro three-dimensional (3D) models have a renaissance, and the rediscovery and development of these technologies are growing ever faster. This recent paper summarises the early history of cell biology/cellular pathology, cell-, tissue culturing, and cancer research models. In addition, we highlight the results of the increasing use of 3D model systems and the 3D bioprinted/biofabricated model developments. Moreover, we present our newly established 3D bioprinted luminal B type breast cancer model system, and the advantages of in vitro 3D models, especially the bioprinted ones. Based on our results and the reviewed developments of in vitro breast cancer models, the heterogeneity and the real in vivo situation of cancer tissues can be represented better by using 3D bioprinted, biofabricated models. However, standardising the 3D bioprinting methods is necessary for future applications in different high-throughput drug tests and patient-derived tumour models. Applying these standardised new models can lead to the point that cancer drug developments will be more successful, efficient, and consequently cost-effective in the near future.

Metabolic Adaptation as Potential Target in Papillary Renal Cell Carcinomas Based on Their In Situ Metabolic Characteristics.

Metabolic characteristics of kidney cancers have mainly been obtained from the most frequent clear cell renal cell carcinoma (CCRCC) studies. Moreover, the bioenergetic perturbances that affect metabolic adaptation possibilities of papillary renal cell carcinoma (PRCC) have not yet been detailed. Therefore, our study aimed to analyze the in situ metabolic features of PRCC vs. CCRCC tissues and compared the metabolic characteristics of PRCC, CCRCC, and normal tubular epithelial cell lines. The protein and mRNA expressions of the molecular elements in mammalian target of rapamycin (mTOR) and additional metabolic pathways were analyzed in human PRCC cases compared to CCRCC. The metabolic protein expression pattern, metabolite content, mTOR, and metabolic inhibitor sensitivity of renal carcinoma cell lines were also studied and compared with tubular epithelial cells, as "normal" control. We observed higher protein expressions of the "alternative bioenergetic pathway" elements, in correlation with the possible higher glutamine and acetate consumption in PRCC cells instead of higher glycolytic and mTOR activity in CCRCCs. Increased expression of certain metabolic pathway markers correlates with the detected differences in metabolite ratios, as well. The lower lactate/pyruvate, lactate/malate, and higher pyruvate/citrate intracellular metabolite ratios in PRCC compared to CCRCC cell lines suggest that ACHN (PRCC) have lower Warburg glycolytic capacity, less pronounced pyruvate to lactate producing activity and shifted OXPHOS phenotype. However, both studied renal carcinoma cell lines showed higher mTOR activity than tubular epithelial cells cultured in vitro, the metabolite ratio, the enzyme expression profiles, and the higher mitochondrial content also suggest increased importance of mitochondrial functions, including mitochondrial OXPHOS in PRCCs. Additionally, PRCC cells showed significant mTOR inhibitor sensitivity and the used metabolic inhibitors increased the effect of rapamycin in combined treatments. Our study revealed in situ metabolic differences in mTOR and metabolic protein expression patterns of human PRCC and CCRCC tissues as well as in cell lines. These underline the importance in the development of specific new treatment strategies, new mTOR inhibitors, and other anti-metabolic drug combinations in PRCC therapy.

Extracellular Vesicle-Mediated Metastasis Suppressors NME1 and NME2 Modify Lipid Metabolism in Fibroblasts.

Nowadays, extracellular vesicles (EVs) raise a great interest as they are implicated in intercellular communication between cancer and stromal cells. Our aim was to understand how vesicular NME1 and NME2 released by breast cancer cells influence the tumour microenvironment. As a model, we used human invasive breast carcinoma cells overexpressing NME1 or NME2, and first analysed in detail the presence of both isoforms in EV subtypes by capillary Western immunoassay (WES) and immunoelectron microscopy. Data obtained by both methods showed that NME1 was present in medium-sized EVs or microvesicles, whereas NME2 was abundant in both microvesicles and small-sized EVs or exosomes. Next, human skin-derived fibroblasts were treated with NME1 or NME2 containing EVs, and subsequently mRNA expression changes in fibroblasts were examined. RNAseq results showed that the expression of fatty acid and cholesterol metabolism-related genes was decreased significantly in response to NME1 or NME2 containing EV treatment. We found that FASN (fatty acid synthase) and ACSS2 (acyl-coenzyme A synthetase short-chain family member 2), related to fatty acid synthesis and oxidation, were underexpressed in NME1/2-EV-treated fibroblasts. Our data show an emerging link between NME-containing EVs and regulation of tumour metabolism.

Immunohistochemical Study of the PD-1/PD-L1 Pathway in Cutaneous Lupus Erythematosus.

The pathomechanism of various autoimmune diseases is known to be associated with the altered function of programmed cell death 1/programmed cell death ligand 1 (PD-1/PD-L1) axis. We aimed to investigate the role of this pathway and inflammatory cell markers in subtypes of cutaneous lupus erythematosus (CLE): discoid lupus erythematosus (DLE), subacute CLE (SCLE) and toxic epidermal necrolysis (TEN)-like lupus, a hyperacute form of acute CLE (ACLE). Ten skin biopsy samples from 9 patients were analyzed with immunohistochemistry regarding the following markers: CD3, CD4, CD8, Granzyme B, CD123, CD163, PD-1, PD-L1. Our group consisted of 4 SCLE (2 idiopathic (I-SCLE) and 2 PD-1 inhibitor-induced (DI-SCLE)), 4 DLE and 1 TEN-like lupus cases. From the latter patient two consecutive biopsies were obtained 1 week apart. Marker expression patterns were compared through descriptive analysis. Higher median keratinocyte (KC) PD-L1 expression was observed in the SCLE group compared to the DLE group (65% and 5%, respectively). Medians of dermal CD4, Granzyme B (GB), PD-1 positive cell numbers and GB+/CD8+ ratio were higher in the DLE group than in the SCLE group. The I-SCLE and DI-SCLE cases showed many similarities, however KC PD-L1 expression and dermal GB positive cell number was higher in the former. The consecutive samples of the TEN-like lupus patient showed an increase by time within the number of infiltrating GB+ cytotoxic T-cells and KC PD-L1 expression (from 22 to 43 and 30%-70%, respectively). Alterations of the PD-1/PD-L1 axis seems to play a role in the pathogenesis of CLE.