SLFN11 captures cancer-immunity interactions associated with platinum sensitivity in high-grade serous ovarian cancer

The role of SLFN11 in DNA replication stress response and its implications for the Fanconi anemia pathway

Fanconi anemia (FA) is a hereditary disorder characterized by a deficiency in the repair of DNA interstrand crosslinks and the response to replication stress. Endogenous DNA damage, most likely caused by aldehydes, severely affects hematopoietic stem cells in FA, resulting in progressive bone marrow failure and the development of leukemia. Recent studies revealed that expression levels of SLFN11 affect the replication stress response and are a strong determinant in cell killing by DNA-damaging cancer chemotherapy. Because SLFN11 is highly expressed in the hematopoietic system, we speculated that SLFN11 may have a significant role in FA pathophysiology. Indeed, we found that DNA damage sensitivity in FA cells is significantly mitigated by the loss of SLFN11 expression. Mechanistically, we demonstrated that SLFN11 destabilizes the nascent DNA strands upon replication fork stalling. In this review, we summarize our work regarding an interplay between SLFN11 and the FA pathway, and the role of SLFN11 in the response to replication stress.

Research into overcoming drug resistance in lung cancer treatment using CRISPR-Cas9 technology: a narrative review

Background and Objective

Lung cancer remains a leading cause of cancer-related mortality globally, with drug resistance posing a significant challenge to effective treatment. The advent of clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated protein 9 (CRISPR-Cas9) technology offers a novel and precise gene-editing technology for targeting and negating drug resistance mechanisms in lung cancer. This review summarizes the research progress in the use of CRISPR-Cas9 technology for investigating and managing drug resistance in lung cancer treatment.

Methods

A literature search was conducted using the Web of Science and PubMed databases, with the following keywords: [CRISPR-Cas9], [lung cancer], [drug resistance], [gene editing], and [gene therapy]. The search was limited to articles published in English from 2002 to September 2023. From the search results, studies that utilized CRISPR-Cas9 technology in the context of lung cancer drug resistance were selected for further analysis and summarize.

Key Content and Findings

CRISPR-Cas9 technology enables precise DNA-sequence editing, allowing for the targeted addition, deletion, or modification of genes. It has been applied to investigate drug resistance in lung cancer by focusing on key genes such as epidermal growth factor receptor (EGFR), Kirsten rat sarcoma viral oncogene homolog (KRAS), tumor protein 53 (TP53), and B-cell lymphoma/leukemia-2 (BCL2), among others. The technology has shown potential in inhibiting tumor growth, repairing mutations, and enhancing the sensitivity of cancer cells to chemotherapy. Additionally, CRISPR-Cas9 has been used to identify novel key genes and molecular mechanisms contributing to drug resistance, offering new avenues for therapeutic intervention. The review also highlights the use of CRISPR-Cas9 in targeting immune escape mechanisms and the development of strategies to improve drug sensitivity.

Conclusions

The CRISPR-Cas9 technology holds great promise for advancing lung cancer treatment, particularly in addressing drug resistance. The ability to precisely target and edit genes involved in resistance pathways offers a powerful tool for developing more effective and personalized therapies. While challenges remain in terms of delivery, safety, and ethical considerations, ongoing research and technological refinements are expected to further enhance the role of CRISPR-Cas9 in improving patient outcomes in lung cancer treatment.

Immunohistochemical Evaluation of Schlafen 11 (SLFN11) Expression in Cancer in the Search of Biomarker-Informed Treatment Targets: A Study of 127 Entities Represented by 6658 Tumors

Schlafen 11 (SLFN11), a DNA/RNA helicase, acts as a regulator of cellular response to replicative stress and irreversibly triggers replication block and cell death. Several preclinical in vitro studies and clinical trials established that SLFN11 expression predicts outcomes in patients with advanced cancer treated with DNA-damaging chemotherapeutics and more recently with poly(ADP-ribose) polymerase inhibitors. SLFN11 expression status remains unknown in many cancer types, especially in mesenchymal tumors. This study evaluated a cohort of well characterized 3808 epithelial and 2850 mesenchymal and neuroectodermal tumors for SLFN11 expression using immunohistochemistry. Nuclear SLFN11 expression was rare in some of the most common carcinomas, for example, hepatocellular (1%), prostatic (2%), colorectal (5%), or breast (16%) cancers. In contrast, other epithelial tumors including mesotheliomas (92%), clear cell renal cell carcinomas (79%), small cell lung cancers (76%), squamous cell carcinomas of the tonsil (89%) and larynx (71%), or ovarian serous carcinomas (69%) were mostly SLFN11-positive. Compared with epithelial malignancies, SLFN11 expression was overall higher in neuroectodermal and mesenchymal tumors. Most positive entities included desmoplastic small round cell tumor (100%), Ewing sarcoma (92%), undifferentiated sarcoma (92%), solitary fibrous tumor (91%), dedifferentiated liposarcoma (89%), synovial sarcoma (86%), and malignant peripheral nerve sheath tumor (85%). Also, this study identifies tumors with potentially worse response to DNA-damaging drugs including antibody drug conjugates due to the absence of SLFN11 expression. Such entities may benefit from alternative treatments or strategies to overcome SLFN11 deficiency-related drug resistance. Our approach and results should serve as a foundation for future biomarker-associated clinical trials.

The emerging role of Schlafen-11 (SLFN11) in predicting response to anticancer treatments: Focus on small cell lung cancer

Small cell lung cancer (SCLC) is characterized by a dismal prognosis. Many efforts have been made so far for identifying novel biomarkers for a personalized treatment for SCLC patients. Schlafen 11 (SLFN11) is a protein differently expressed in many cancers and recently emerged as a new potential biomarker. Lower expression of SLFN11 correlates with a worse prognosis in SCLC and other tumors. SLFN11 has a role in tumorigenesis, inducing replication arrest in the presence of DNA damage through the block of the replication fork. SLFN11 interacts also with chromatin accessibility, proteotoxic stress and mammalian target of rapamycin signalling pathway. The expression of SLFN11 is regulated by epigenetic mechanisms, including promoter methylation, histone deacetylation, and the histone methylation. The downregulation of SLFN11 correlates with a worse response to topoisomerase I and II inhibitors, alkylating agents, and poly ADP-ribose polymerase inhibitors in different cancer types. Some studies exploring strategies for overcoming drug resistance in tumors with low levels of SLFN11 showed promising results. One of these strategies includes the interaction with the Ataxia Telangiectasia and Rad3-related pathway, constitutively activated and leading to cell survival and tumor growth in the presence of low levels of SLFN11. Furthermore, the expression of SLFN11 is dynamic through time and different anticancer therapy and liquid biopsy seems to be an attractive tool for catching SLFN11 different expressions. Despite this, further investigations exploring SLFN11 as a predictive biomarker, its longitudinal changes, and new strategies to overcome drug resistances are needed.

DNA damage induces p53-independent apoptosis through ribosome stalling

In response to excessive DNA damage, human cells can activate p53 to induce apoptosis. Cells lacking p53 can still undergo apoptosis upon DNA damage, yet the responsible pathways are unknown. We observed that p53-independent apoptosis in response to DNA damage coincided with translation inhibition, which was characterized by ribosome stalling on rare leucine-encoding UUA codons and globally curtailed translation initiation. A genetic screen identified the transfer RNAse SLFN11 and the kinase GCN2 as factors required for UUA stalling and global translation inhibition, respectively. Stalled ribosomes activated a ribotoxic stress signal conveyed by the ribosome sensor ZAKα to the apoptosis machinery. These results provide an explanation for the frequent inactivation of SLFN11 in chemotherapy-unresponsive tumors and highlight ribosome stalling as a signaling event affecting cell fate in response to DNA damage.

Schlafens: Emerging Therapeutic Targets

The interferon (IFN) family of immunomodulatory cytokines has been a focus of cancer research for over 50 years with direct and indirect implications in cancer therapy due to their properties to inhibit malignant cell proliferation and modulate immune responses. Among the transcriptional targets of the IFNs is a family of genes referred to as Schlafens. The products of these genes, Schlafen proteins, exert important roles in modulating cellular proliferation, differentiation, immune responses, viral replication, and chemosensitivity of malignant cells. Studies have demonstrated that abnormal expression of various Schlafens contributes to the pathophysiology of various cancers. Schlafens are now emerging as promising biomarkers and potentially attractive targets for drug development in cancer research. Here, we highlight research suggesting the use of Schlafens as cancer biomarkers and the rationale for the development of specific drugs targeting Schlafen proteins.

SLFN11 is a BRCA Independent Biomarker for the Response to Platinum-Based Chemotherapy in High-Grade Serous Ovarian Cancer and Clear Cell Ovarian Carcinoma

BRCA1/2 mutations are robust biomarkers for platinum-based chemotherapy in epithelial ovarian cancers. However, BRCA1/2 mutations in clear cell ovarian carcinoma (CCC) are less frequent compared with high-grade serous ovarian cancer (HGSC). The discovery of biomarkers that can be applied to CCC is an unmet need in chemotherapy. Schlafen 11 (SLFN11) has attracted attention as a novel sensitizer for DNA-damaging agents including platinum. In this study, we investigated the utility of SLFN11 in HGSC and CCC for platinum-based chemotherapy. SLFN11 expression was analyzed retrospectively by IHC across 326 ovarian cancer samples. The clinicopathologic significance of SLFN11 expression was analyzed across 57 advanced HGSC as a discovery set, 96 advanced HGSC as a validation set, and 57 advanced CCC cases, all of whom received platinum-based chemotherapy. BRCA1/2 mutation was analyzed using targeted-gene sequencing. In the HGSC cohort, the SLFN11-positive and BRCA mutation group showed significantly longer whereas the SLFN11-negative and BRCA wild-type group showed significantly shorter progression-free survival and overall survival. Moreover, SLFN11-positive HGSC shrunk significantly better than SLFN11-negative HGSC after neoadjuvant chemotherapy. Comparable results were obtained with CCC but without consideration of BRCA1/2 mutation due to a small population. Multivariate analysis identified SLFN11 as an independent factor for better survival in HGSC and CCC. The SLFN11-dependent sensitivity to platinum and PARP inhibitors were validated with genetically modified non-HGSC ovarian cancer cell lines. Our study reveals that SLFN11 predicts platinum sensitivity in HGSC and CCC independently of BRCA1/2 mutation status, indicating that SLFN11 assessment can guide treatment selection in HGSC and CCC.

Prediction of Chemoresistance-How Preclinical Data Could Help to Modify Therapeutic Strategy in High-Grade Serous Ovarian Cancer

High-grade serous ovarian cancer (HGSOC) is one of the most lethal tumors generally and the most fatal cancer of the female genital tract. The approved standard therapy consists of surgical cytoreduction and platinum/taxane-based chemotherapy, and of targeted therapy in selected patients. The main therapeutic problem is chemoresistance of recurrent and metastatic HGSOC tumors which results in low survival in the group of FIGO III/IV. Therefore, the prediction and monitoring of chemoresistance seems to be of utmost importance for the improvement of HGSOC management. This type of cancer has genetic heterogeneity with several subtypes being characterized by diverse gene signatures and disturbed peculiar epigenetic regulation. HGSOC develops and metastasizes preferentially in the specific intraperitoneal environment composed mainly of fibroblasts, adipocytes, and immune cells. Different HGSOC subtypes could be sensitive to distinct sets of drugs. Moreover, primary, metastatic, and recurrent tumors are characterized by an individual biology, and thus diverse drug responsibility. Without a precise identification of the tumor and its microenvironment, effective treatment seems to be elusive. This paper reviews tumor-derived genomic, mutational, cellular, and epigenetic biomarkers of HGSOC drug resistance, as well as tumor microenvironment-derived biomarkers of chemoresistance, and discusses their possible use in the novel complex approach to ovarian cancer therapy and monitoring.

The crucial role of single-stranded DNA binding in enhancing sensitivity to DNA-damaging agents for Schlafen 11 and Schlafen 13

Schlafen (SLFN) 11 enhances cellular sensitivity to various DNA-damaging anticancer agents. Among the human SLFNs (SLFN5/11/12/13/14), SLFN11 is unique in its drug sensitivity and ability to block replication under DNA damage. In biochemical analysis, SLFN11 binds single-stranded DNA (ssDNA), and this binding is enhanced by the dephosphorylation of SLFN11. In this study, human cell-based assays demonstrated that a point mutation at the ssDNA-binding site of SLFN11 or a constitutive phosphorylation mutant abolished SLFN11-dependent drug sensitivity. Additionally, we discovered that nuclear SLFN13 with a point mutation mimicking the DNA-binding site of SLFN11 was recruited to chromatin, blocked replication, and enhanced drug sensitivity. Through generating multiple mutants and structure analyses of SLFN11 and SLFN13, we identified protein phosphatase 2A as a binding partner of SLFN11 and the putative binding motif in SLFN11. These findings provide crucial insights into the unique characteristics of SLFN11, contributing to a better understanding of its mechanisms.

Modulation of SLFN11 induces changes in DNA Damage response in breast cancer

BACKGROUND

Lack of Schlafen family member 11 (SLFN11) expression has been recently identified as a dominant genomic determinant of response to DNA damaging agents in numerous cancer types. Thus, several strategies aimed at increasing SLFN11 are explored to restore chemosensitivity of refractory cancers. In this study, we examined various approaches to elevate SLFN11 expression in breast cancer cellular models and confirmed a corresponding increase in chemosensitivity with using the most successful efficient one. As oncogenic transcriptomic downregulation is often driven by methylation of the promotor region, we explore the demethylation effect of 5-aza-2'-deoxycytidine (decitabine), on the SLFN11 gene. Since SLFN11 has been reported as an interferon inducible gene, and interferon is secreted during an active anti-tumor immune response, we investigated the in vitro effect of IFN-γ on SLFN11 expression in breast cancer cell lines. As a secondary approach to pick up cross talk between immune cells and SLFN11 expression we used indirect co-culture of breast cancer cells with activated PBMCs and evaluated if this can drive SLFN11 upregulation. Finally, as a definitive and specific way to modulate SLFN11 expression we implemented SLFN11 dCas9 (dead CRISPR associated protein 9) systems to specifically increase or decrease SLFN11 expression.

RESULTS

After confirming the previously reported correlation between methylation of SLFN11 promoter and its expression across multiple cell lines, we showed in-vitro that decitabine and IFN-γ could increase moderately the expression of SLFN11 in both BT-549 and T47D cell lines. The use of a CRISPR-dCas9 UNISAM and KRAB system could increase or decrease SLFN11 expression significantly (up to fivefold), stably and specifically in BT-549 and T47D cancer cell lines. We then used the modified cell lines to quantify the alteration in chemo sensitivity of those cells to treatment with DNA Damaging Agents (DDAs) such as Cisplatin and Epirubicin or DNA Damage Response (DDRs) drugs like Olaparib. RNAseq was used to elucidate the mechanisms of action affected by the alteration in SLFN11 expression. In cell lines with robust SLFN11 promoter methylation such as MDA-MB-231, no SLFN11 expression could be induced by any approach.

CONCLUSION

To our knowledge this is the first report of the stable non-lethal increase of SLFN11 expression in a cancer cell line. Our results show that induction of SLFN11 expression can enhance DDA and DDR sensitivity in breast cancer cells and dCas9 systems may represent a novel approach to increase SLFN11 and achieve higher sensitivity to chemotherapeutic agents, improving outcome or decreasing required drug concentrations. SLFN11-targeting therapies might be explored pre-clinically to develop personalized approaches.

Epigenetic upregulation of Schlafen11 renders WNT- and SHH-activated medulloblastomas sensitive to cisplatin

BACKGROUND

Intensive chemotherapeutic regimens with craniospinal irradiation have greatly improved survival in medulloblastoma patients. However, survival markedly differs among molecular subgroups and their biomarkers are unknown. Through unbiased screening, we found Schlafen family member 11 (SLFN11), which is known to improve response to DNA damaging agents in various cancers, to be one of the top prognostic markers in medulloblastomas. Hence, we explored the expression and functions of SLFN11 in medulloblastoma.

METHODS

SLFN11 expression for each subgroup was assessed by immunohistochemistry in 98 medulloblastoma patient samples and by analyzing transcriptomic databases. We genetically or epigenetically modulated SLFN11 expression in medulloblastoma cell lines and determined cytotoxic response to the DNA damaging agents cisplatin and topoisomerase I inhibitor SN-38 in vitro and in vivo.

RESULTS

High SLFN11 expressing cases exhibited significantly longer survival than low expressing cases. SLFN11 was highly expressed in the WNT-activated subgroup and in a proportion of the SHH-activated subgroup. While WNT activation was not a direct cause of the high expression of SLFN11, a specific hypomethylation locus on the SLFN11 promoter was significantly correlated with high SLFN11 expression. Overexpression or deletion of SLFN11 made medulloblastoma cells sensitive and resistant to cisplatin and SN-38, respectively. Pharmacological upregulation of SLFN11 by the brain-penetrant histone deacetylase-inhibitor RG2833 markedly increased sensitivity to cisplatin and SN-38 in SLFN11-negative medulloblastoma cells. Intracranial xenograft studies also showed marked sensitivity to cisplatin by SLFN11-overexpression in medulloblastoma cells.

CONCLUSIONS

High SLFN11 expression is one factor which renders favorable outcomes in WNT-activated and a subset of SHH-activated medulloblastoma possibly through enhancing response to cisplatin.

Disruption of SLFN11 Deficiency-Induced CCL2 Signaling and Macrophage M2 Polarization Potentiates Anti-PD-1 Therapy Efficacy in Hepatocellular Carcinoma

BACKGROUND & AIMS

The therapeutic effect of immune checkpoint inhibitors (ICIs) is poor in hepatocellular carcinoma (HCC) and varies greatly among individuals. Schlafen (SLFN) family members have important functions in immunity and oncology, but their roles in cancer immunobiology remain unclear. We aimed to investigate the role of the SLFN family in immune responses against HCC.

METHODS

Transcriptome analysis was performed in human HCC tissues with or without response to ICIs. A humanized orthotopic HCC mouse model and a co-culture system were constructed, and cytometry by time-of-flight technology was used to explore the function and mechanism of SLFN11 in the immune context of HCC.

RESULTS

SLFN11 was significantly up-regulated in tumors that responded to ICIs. Tumor-specific SLFN11 deficiency increased the infiltration of immunosuppressive macrophages and aggravated HCC progression. HCC cells with SLFN11 knockdown promoted macrophage migration and M2-like polarization in a C-C motif chemokine ligand 2-dependent manner, which in turn elevated their own PD-L1 expression by activating the nuclear factor-κB pathway. Mechanistically, SLFN11 suppressed the Notch pathway and C-C motif chemokine ligand 2 transcription by binding competitively with tripartite motif containing 21 to the RNA recognition motif 2 domain of RBM10, thereby inhibiting tripartite motif containing 21-mediated RBM10 degradation to stabilize RBM10 and promote NUMB exon 9 skipping. Pharmacologic antagonism of C-C motif chemokine receptor 2 potentiated the antitumor effect of anti-PD-1 in humanized mice bearing SLFN11 knockdown tumors. ICIs were more effective in patients with HCC with high serum SLFN11 levels.

CONCLUSIONS

SLFN11 serves as a critical regulator of microenvironmental immune properties and an effective predictive biomarker of ICIs response in HCC. Blockade of C-C motif chemokine ligand 2/C-C motif chemokine receptor 2 signaling sensitized SLFN11^low HCC patients to ICI treatment.

Comprehensive analyses of a tumor-infiltrating lymphocytes-related gene signature regarding the prognosis and immunologic features for immunotherapy in bladder cancer on the basis of WGCNA

Tumor-infiltrating lymphocyte (TIL) is a class of cells with important immune functions and plays a crucial role in bladder cancer (BCa). Several studies have shown the clinical significance of TIL in predicting the prognosis and immunotherapy efficacy. TIL-related gene module was screened utilizing weighted gene coexpression network analysis. We screened eight TIL-related genes utilizing univariate Cox regression analysis, least absolute shrinkage and selection operator (LASSO) Cox regression analysis, and multivariate Cox regression analysis. Then, we established a TIL-related signature model containing the eight selected genes and subsequently classified all patients into two groups, that is, the high-risk as well as low-risk groups. Gene mutation status, prognosis, immune cell infiltration, immune subtypes, TME, clinical features, and immunotherapy response were assessed among different risk subgroups. The results affirmed that the TIL-related signature model was a reliable predictor of overall survival (OS) for BCa and was determined as an independent risk factor for BCa patients in two cohorts. Moreover, the risk score was substantially linked to age, tumor staging, TNM stage, and pathological grade. And there were different mutational profiles, biological pathways, immune scores, stromal scores, and immune cell infiltration in the tumor microenvironment (TME) between the two risk groups. In particular, immune checkpoint genes’ expression was remarkably different between the two risk groups, with patients belonging to the low-risk group responding better to immune checkpoint inhibition (ICI) therapy. In conclusion, our study demonstrates that the TIL-related model was a reliable signature in anticipating prognosis, immune status, and immunotherapy response, which can help in screening patients who respond to immunotherapy.

Reconsidering the mechanisms of action of PARP inhibitors based on clinical outcomes

PARP inhibitors (PARPis) were initially developed as DNA repair inhibitors that inhibit the catalytic activity of PARP1 and PARP2 and are expected to induce synthetic lethality in BRCA‐ or homologous recombination (HR)‐deficient tumors. However, the clinical indications for PARPis are not necessarily limited to BRCA mutations or HR deficiency; BRCA wild‐type and HR‐proficient cancers can also derive some benefit from PARPis. These facts are interpretable by an additional primary antitumor mechanism of PARPis named PARP trapping, resulting from the stabilization of PARP‐DNA complexes. Favorable response to platinum derivatives (cisplatin and carboplatin) in preceding treatment is used as a clinical biomarker for some PARPis, implying that sensitivity factors for platinum derivatives and PARPis are mainly common. Such common sensitivity factors include not only HR defects (HRD) but also additional factors. One of them is Schlafen 11 (SLFN11), a putative DNA/RNA helicase, that sensitizes cancer cells to a broad type of DNA‐damaging agents, including platinum and topoisomerase inhibitors. Mechanistically, SLFN11 induces a lethal replication block in response to replication stress (ie, DNA damage). As SLFN11 acts upon replication stress, trapping PARPis can activate SLFN11. Preclinical models show the importance of SLFN11 in PARPi sensitivity. However, the relevance of SLFN11 in PARPi response is less evident in clinical data compared with the significance of SLFN11 for platinum sensitivity. In this review, we consider the reasons for variable indications of PARPis resulting from clinical outcomes and review the mechanisms of action for PARPis as anticancer agents.

Can Schlafen 11 Help to Stratify Ovarian Cancer Patients Treated with DNA-Damaging Agents?

Platinum-based chemotherapy has been the cornerstone of systemic treatment in ovarian cancer. Since no validated molecular predictive markers have been identified yet, the response to platinum-based chemotherapy has been evaluated clinically, based on platinum-free interval. The new promising marker Schlafen 11 seems to correlate with sensitivity or resistance to DNA-damaging agents, including platinum compounds or PARP inhibitors in various types of cancer. We provide background information about the function of Schlafen 11, its evaluation in tumor tissue, and its prevalence in ovarian cancer. We discuss the current evidence of the correlation of Schlafen 11 expression in ovarian cancer with treatment outcomes and the potential use of Schlafen 11 as the key predictive and prognostic marker that could help to better stratify ovarian cancer patients treated with platinum-based chemotherapy or PARP inhibitors. We also provide perspectives on future directions in the research on this promising marker.

Dynamic expression of Schlafen 11 (SLFN11) in circulating tumour cells as a liquid biomarker in small cell lung cancer

INTRODUCTION

Small cell lung cancer (SCLC) is an aggressive malignancy with no established biomarkers. Schlafen 11(SLFN11), a DNA/RNA helicase that sensitises cancer cells to DNA-damaging agents, has emerged as a promising predictive biomarker for several drug classes including platinum and PARP inhibitors. Detection of SLFN11 in circulating tumour cells (CTCs) may provide a valuable alternative to tissue sampling.

METHODS

SLFN11 expression was evaluated in tumour samples and characterised in circulating tumour cells (CTC) longitudinally to determine its potential role as a biomarker of response.

RESULTS

Among 196 SCLC tumours, 51% expressed SLFN11 by IHC. In addition, 20/29 extra-thoracic high-grade neuroendocrine tumours expressed SLFN11 expression. In 64 blood samples from 42 SCLC patients, 83% (53/64) of samples had detectable CTCs, and SLFN11-positive CTCs were detected in 55% (29/53). Patients actively receiving platinum treatment had the lowest number of CTCs and a lower percentage of SLFN11-positive CTCs (p = 0.014). Analysis from patients with longitudinal samples suggest a decrease in CTC number and in SLFN11 expression that correlates with clinical response.

CONCLUSIONS

SLFN11 levels can be monitored in CTCs from SCLC patients using non-invasive liquid biopsies. The ability to detect SLFN11 in CTCs from SCLC patients adds a valuable tool for the detection and longitudinal monitoring of this promising biomarker.

Prognostic Significance of SLFN11 Methylation in Plasma Cell-Free DNA in Advanced High-Grade Serous Ovarian Cancer

Background: Epigenetic alterations in ctDNA are highly promising as a source of novel potential liquid biopsy biomarkers and comprise a very promising liquid biopsy approach in ovarian cancer, for early diagnosis, prognosis and response to treatment. Methods: In the present study, we examined the methylation status of six gene promoters (BRCA1, CST6, MGMT, RASSF10, SLFN11 and USP44) in high-grade serous ovarian cancer (HGSOC). We evaluated the prognostic significance of DNA methylation of these six gene promoters in primary tumors (FFPEs) and plasma cfDNA samples from patients with early, advanced and metastatic HGSOC. Results: We report for the first time that the DNA methylation of SLFN11 in plasma cfDNA was significantly correlated with worse PFS (p = 0.045) in advanced stage HGSOC. Conclusions: Our results strongly indicate that SLFN11 epigenetic inactivation could be a predictor of resistance to platinum drugs in ovarian cancer. Our results should be further validated in studies based on a larger cohort of patients, in order to further explore whether the DNA methylation of SLFN11 promoter could serve as a potential prognostic DNA methylation biomarker and a predictor of resistance to platinum-based chemotherapy in ovarian cancer.