GSDME and its role in cancer: From behind the scenes to the front of the stage.

Gasdermin E (GSDME), a gene originally involved in hereditary hearing loss, has been associated with several types of cancer in the last two decades. Recently, GSDME was identified as a pore-forming molecule, which is activated following caspase-3-mediated cleavage resulting in so-called secondary necrosis following apoptotic cell death, or in primary necrotic cell death without an apoptotic phase, so-called pyroptosis-like. This implication in cell death execution suggests its potential role as a tumor suppressor. GSDME also exhibited a cancer type-specific differential methylation pattern between tumor tissues and normal cells, implying GSDME gene methylation as both a pan-cancer and cancer type-specific detection biomarker. A bit paradoxically, GSDME protein expression is considered to be less suited as biomarker, and although its ablation does not protect the cell against eventual cell death, its protein expression might still operate in tumor immunogenicity due to its capacity to induce (secondary) necrotic cell death, which has enhanced immunogenic properties. Additionally, GSDME gene expression has been shown to be associated with favorable prognosis following chemotherapy, and it could therefore be a potential predictive biomarker. We provide an overview of the different associations between GSDME gene methylation, gene expression and tumorigenesis, and explore their potential use in the clinic. Our review only focuses on GSDME and summarizes the current knowledge and most recent advances on GSDME's role in cancer formation, its potential as a biomarker in cancer and on its promising role in immunotherapies and antitumor immune response.

First Evidence of Activity of Enfortumab Vedotin on Brain Metastases in Urothelial Cancer Patients.

Enfortumab vedotin (EV), an antibody-drug conjugate directed against Nectin-4, significantly prolonged survival compared to standard chemotherapy in patients with locally advanced or metastatic urothelial carcinoma who previously received platinum-based chemotherapy and a PD-1 or PD-L1 inhibitor. The overall response rate in the phase 3 EV301 trial leading to approval was 40.6%. However, no data have been published yet regarding the effect of EV on brain metastases. Here, we present three patients from different centers with brain metastases receiving EV. A 58-year-old white male patient, who had been heavily pretreated for urothelial carcinoma with visceral metastases and a solitary clinically active brain metastasis, started on EV 1.25 mg/kg on days 1, 8, and 15 of a 28-day cycle. After three cycles, the first evaluation showed a partial remission by RECIST v1.1, with a near complete response on the brain metastasis and disappearance of neurological symptoms. The patient is currently still receiving EV. A second, 74-year-old male patient started on the same regimen, after previous progression on platinum-based chemotherapy and avelumab in maintenance. The patient achieved a complete response and received therapy for five months. Nevertheless, therapy was discontinued at the patient's request. Shortly after, he developed new leptomeningeal metastases. Upon rechallenge with EV, there was a significant reduction in the diffuse meningeal infiltration. A third, 50-year-old white male patient also received EV after previous progression on cisplatin-gemcitabine and atezolizumab maintenance, followed by palliative whole-brain radiotherapy and two cycles of vinflunine. After three cycles of EV, there was a significant reduction in the brain metastases. The patient is currently still receiving EV. These are the first reports on the efficacy of EV in patients with urothelial carcinoma and active brain metastases.

Extensive CArdioVAscular Characterization and Follow-Up of Patients Receiving Immune Checkpoint Inhibitors: A Prospective Multicenter Study.

BACKGROUND: The increasing use of immune checkpoint inhibitors (ICIs) in the treatment of both advanced and early stages of various malignancies has resulted in a substantial increase in the incidence of cardiovascular (CV) immune-related adverse events (irAEs). The current follow-up guidelines are based on anecdotal evidence and expert opinions, due to a lack of solid data and prospective studies. As many questions remain unanswered, cardiac monitoring, in patients receiving ICIs, is not always implemented by oncologists. Hence, an urgent need to investigate the possible short- and long-term CV effects of ICIs, as ICI approval is continuing to expand to the (neo)adjuvant setting. METHODS: We have initiated a prospective, multicenter study, i.e., the CAVACI trial, in which a minimum of 276 patients with a solid tumor, eligible for ICI treatment, will be enrolled. The study consists of routine investigations of blood parameters (troponin and N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels, in particular) and a thorough CV follow-up (electrocardiograms, transthoracic echocardiograms, and coronary calcium scoring) at fixed time points for a total period of two years. The primary endpoint is the cumulative incidence of troponin elevation in the first three months of ICI treatment, compared to baseline levels. Furthermore, secondary endpoints include incidence above the upper limit of normal of both troponin and NT-proBNP levels, evolution in troponin and NT-proBNP levels, the incidence of CV abnormalities/major adverse cardiac events, evaluation of associations between patient characteristics/biochemical parameters and CV events, transthoracic echocardiography parameters, electrocardiography parameters, and progression of coronary atherosclerosis. Recruitment of patients started in January 2022. Enrolment is ongoing in AZ Maria Middelares, Antwerp University Hospital, AZ Sint-Vincentius Deinze, and AZ Sint-Elisabeth Zottegem. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT05699915, registered 26 January 2023.

Humoral and Cellular Immune Responses against SARS-CoV-2 after Third Dose BNT162b2 following Double-Dose Vaccination with BNT162b2 versus ChAdOx1 in Patients with Cancer.

PURPOSE: Patients with cancer display reduced humoral responses after double-dose COVID-19 vaccination, whereas their cellular response is more comparable with that in healthy individuals. Recent studies demonstrated that a third vaccination dose boosts these immune responses, both in healthy people and patients with cancer. Because of the availability of many different COVID-19 vaccines, many people have been boosted with a different vaccine from the one used for double-dose vaccination. Data on such alternative vaccination schedules are scarce. This prospective study compares a third dose of BNT162b2 after double-dose BNT162b2 (homologous) versus ChAdOx1 (heterologous) vaccination in patients with cancer. EXPERIMENTAL DESIGN: A total of 442 subjects (315 patients and 127 healthy) received a third dose of BNT162b2 (230 homologous vs. 212 heterologous). Vaccine-induced adverse events (AE) were captured up to 7 days after vaccination. Humoral immunity was assessed by SARS-CoV-2 anti-S1 IgG antibody levels and SARS-CoV-2 50% neutralization titers (NT50) against Wuhan and BA.1 Omicron strains. Cellular immunity was examined by analyzing CD4+ and CD8+ T-cell responses against SARS-CoV-2-specific S1 and S2 peptides. RESULTS: Local AEs were more common after heterologous boosting. SARS-CoV-2 anti-S1 IgG antibody levels did not differ significantly between homologous and heterologous boosted subjects [GMT 1,755.90 BAU/mL (95% CI, 1,276.95-2,414.48) vs. 1,495.82 BAU/mL (95% CI, 1,131.48-1,977.46)]. However, homologous-boosted subjects show significantly higher NT50 values against BA.1 Omicron. Subjects receiving heterologous boosting demonstrated increased spike-specific CD8+ T cells, including higher IFNγ and TNFα levels. CONCLUSIONS: In patients with cancer who received double-dose ChAdOx1, a third heterologous dose of BNT162b2 was able to close the gap in antibody response.

Intermediate molecular phenotypes to identify genetic markers of anthracycline-induced cardiotoxicity risk.

Cardiotoxicity due to anthracyclines (CDA) affects cancer patients, but we cannot predict who may suffer from this complication. CDA is a complex disease whose polygenic component is mainly unidentified. We propose that levels of intermediate molecular phenotypes in the myocardium associated with histopathological damage could explain CDA susceptibility; so that variants of genes encoding these intermediate molecular phenotypes could identify patients susceptible to this complication. A genetically heterogeneous cohort of mice generated by backcrossing (N = 165) was treated with doxorubicin and docetaxel. Cardiac histopathological damage was measured by fibrosis and cardiomyocyte size by an Ariol slide scanner. We determine intramyocardial levels of intermediate molecular phenotypes of CDA associated with histopathological damage and quantitative trait loci (ipQTLs) linked to them. These ipQTLs seem to contribute to the missing heritability of CDA because they improve the heritability explained by QTL directly linked to CDA (cda-QTLs) through genetic models. Genes encoding these molecular subphenotypes were evaluated as genetic markers of CDA in three cancer patient cohorts (N = 517) whose cardiac damage was quantified by echocardiography or Cardiac Magnetic Resonance. Many SNPs associated with CDA were found using genetic models. LASSO multivariate regression identified two risk score models, one for pediatric cancer patients and the other for women with breast cancer. Molecular intermediate phenotypes associated with heart damage can identify genetic markers of CDA risk, thereby allowing a more personalized patient management. A similar strategy could be applied to identify genetic markers of other complex trait diseases.

Intermediate Molecular Phenotypes to Identify Genetic Markers of Anthracycline-Induced Cardiotoxicity Risk.

Cardiotoxicity due to anthracyclines (CDA) affects cancer patients, but we cannot predict who may suffer from this complication. CDA is a complex trait with a polygenic component that is mainly unidentified. We propose that levels of intermediate molecular phenotypes (IMPs) in the myocardium associated with histopathological damage could explain CDA susceptibility, so variants of genes encoding these IMPs could identify patients susceptible to this complication. Thus, a genetically heterogeneous cohort of mice (n = 165) generated by backcrossing were treated with doxorubicin and docetaxel. We quantified heart fibrosis using an Ariol slide scanner and intramyocardial levels of IMPs using multiplex bead arrays and QPCR. We identified quantitative trait loci linked to IMPs (ipQTLs) and cdaQTLs via linkage analysis. In three cancer patient cohorts, CDA was quantified using echocardiography or Cardiac Magnetic Resonance. CDA behaves as a complex trait in the mouse cohort. IMP levels in the myocardium were associated with CDA. ipQTLs integrated into genetic models with cdaQTLs account for more CDA phenotypic variation than that explained by cda-QTLs alone. Allelic forms of genes encoding IMPs associated with CDA in mice, including AKT1, MAPK14, MAPK8, STAT3, CAS3, and TP53, are genetic determinants of CDA in patients. Two genetic risk scores for pediatric patients (n = 71) and women with breast cancer (n = 420) were generated using machine-learning Least Absolute Shrinkage and Selection Operator (LASSO) regression. Thus, IMPs associated with heart damage identify genetic markers of CDA risk, thereby allowing more personalized patient management.

Ipilimumab- and nivolumab-induced myocarditis in a patient with metastatic cholangiocarcinoma: a case report.

BACKGROUND: Myocarditis in patients treated with immune checkpoint inhibitors has previously been reported to be rare, though it has most likely been underreported owing to misdiagnosis in the absence of overt clinical presentation. Early detection and characterization of this potentially life-threatening immune-related adverse event is of major importance. Herein we report a case of early-onset myocarditis in an asymptomatic patient treated with dual checkpoint inhibition for metastatic cholangiocarcinoma. CASE PRESENTATION: A 69-year-old male Caucasian patient with metastatic cholangiocarcinoma presented with mild epigastric pain and troponinemia prior to the third dose of dual checkpoint inhibition (ipilimumab 1 mg/kg body weight and nivolumab 3 mg/kg body weight). Initial workup showed no significant abnormalities (physical/neurological examination, electrocardiogram, 72-hour Holter monitoring, and a transthoracic echocardiogram). However, cardiac magnetic resonance imaging revealed a zone of contrast enhancement in the inferior segment of the left ventricular wall indicating a recent episode of myocarditis. Despite steroid initiation (0.5 mg/kg oral prednisolone per day), troponin levels kept increasing, in the absence of coronary disease, for which steroids were increased to 1.5 mg/kg/day. Fluorodeoxyglucose positron emission tomography/computed tomography, 28 days after detecting elevated troponin levels, depicted multiple zones of active myocardial inflammation (basal septal, mid-anterior, and apical inferior). The patient is currently stable, and troponinemia is slowly decreasing while steroids are steadily being tapered. CONCLUSION: As the number of cancers treated with immune checkpoint inhibitors is expanding, the incidence of immune checkpoint inhibitor-induced myocarditis is likely to increase. Moreover, the emerging combination of immune checkpoint inhibitors with non-immune checkpoint inhibitor therapies with potential synergistic cardiotoxic side effects (for example, tyrosine kinase inhibitors) will further complicate the diagnosis of immune-related cardiotoxicity. This case highlights the urgent need for predictive biomarkers to stratify patients at risk and to develop a standardized and multidisciplinary management approach for early diagnosis and treatment of this severe immune-related adverse event.

Immunoglobin G/total antibody testing for SARS-CoV-2: A prospective cohort study of ambulatory patients and health care workers in two Belgian oncology units comparing three commercial tests.

BACKGROUND: Coronavirus disease (COVID-19) is interfering heavily with the screening, diagnosis and treatment of cancer patients. Better knowledge of the seroprevalence and immune response after Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection in this population is important to manage them safely during the pandemic. METHODS: 922 cancer patients, 100 non-cancer patients and 94 health care workers (HCW) attending the Multidisciplinary Oncology Unit of Antwerp University Hospital from 24th of March 2020 till 31st of May 2020, and the Oncology Unit of AZ Maria Middelares Hospital, Ghent, from 13th of April 2020 till 31st of May 2020 participated in the study. The Alinity® (A; Abbott) and Liaison® (D; DiaSorin) commercially available assays were used to measure SARS-CoV-2 IgG, while total SARS-CoV-2 Ig was measured by Elecsys® (R; Roche). RESULTS: In the overall study population IgG/total SARS-CoV-2 antibodies were found in respectively 32/998 (3.2%), 68/1020 (6.7%), 37/1010 (3.7%) and of individuals using the A, D or R test. Forty-six out of 618 (7.4%) persons had a positive SARS-CoV-2 polymerase chain reaction (RT-PCR) test. Seroprevalence in cancer patients (A:2.2%, D:6.2%, R:3.0%), did not significantly differ from that in non-cancer patients (A:1.1%, D:5.6%, R:0.0%), but was lower than the HCW (A:13%, D:12%, R:12%; respectively Fisher's exact test p = 0.00001, p = 0.046, p = 0.0004). A positive SARS-CoV-2 RT-PCR was found in 6.8% of the cancer patients, 2.3% of the non-cancer patients and 28.1% of the HCW (Fisher's exact test p = 0.0004). Correlation between absolute values of the different Ig tests was poor in the cancer population. Dichotomising a positive versus negative test result, the A and R test correlated well (kappa 0.82 p McNemar test = 0.344), while A and D and R and D did not (respectively kappa 0.49 and 0.57; result significantly different p McNemar test = <0.0001 for both). The rate of seroconversion (>75%) and median absolute antibody levels (A: 7.0 versus 4.7; D 74.0 versus 26.6, R: 16.34 versus 7.32; all >P Mann Whitney U test = 0.28) in cancer patients and HCW with a positive RT-PCR at least 7 days earlier did not show any differences. However, none (N = 0/4) of the patients with hematological tumours had seroconversion and absolute antibody levels remained much lower compared to patients with solid tumours (R: 0.1 versus 37.6, p 0.003; D 4.1 versus 158, p 0.008) or HCW (all p < 0.0001). CONCLUSION: HCW were at high risk of being infected by SARS-CoV-2 during the first wave of the pandemic. Seroprevalence in cancer patients was low in the study period. Although Ig immune response in cancer patients with solid tumours does not differ from healthy volunteers, patients with hematological tumours have a very poor humoral immune response. This has to be taken into account in future vaccination programmes in this population. SARS-CoV-2 antibody tests have divergent results and seem to have little added value in the management of cancer patients.

Blood Cytokine Analysis Suggests That SARS-CoV-2 Infection Results in a Sustained Tumour Promoting Environment in Cancer Patients.

Cytokines, chemokines, and (angiogenic) growth factors (CCGs) have been shown to play an intricate role in the progression of both solid and haematological malignancies. Recent studies have shown that SARS-CoV-2 infection leads to a worse outcome in cancer patients, especially in haematological malignancy patients. Here, we investigated how SARS-CoV-2 infection impacts the already altered CCG levels in solid or haematological malignancies, specifically, whether there is a protective effect or rather a potentially higher risk for major COVID-19 complications in cancer patients due to elevated CCGs linked to cancer progression. Serially analysing immune responses with 55 CCGs in cancer patients under active treatment with or without SARS-CoV-2 infection, we first showed that cancer patients without SARS-CoV-2 infection (n = 54) demonstrate elevated levels of 35 CCGs compared to the non-cancer, non-infected control group of health care workers (n = 42). Of the 35 CCGs, 19 were common to both the solid and haematological malignancy groups and comprised previously described cytokines such as IL-6, TNF-α, IL-1Ra, IL-17A, and VEGF, but also several less well described cytokines/chemokines such as Fractalkine, Tie-2, and T cell chemokine CTACK. Importantly, we show here that 7 CCGs are significantly altered in SARS-CoV-2 exposed cancer patients (n = 52). Of these, TNF-α, IFN-ß, TSLP, and sVCAM-1, identified to be elevated in haematological cancers, are also known tumour-promoting factors. Longitudinal analysis conducted over 3 months showed persistence of several tumour-promoting CCGs in SARS-CoV-2 exposed cancer patients. These data demonstrate a need for increased vigilance for haematological malignancy patients as a part of long COVID follow-up.

Determination of the Potential Tumor-Suppressive Effects of Gsdme in a Chemically Induced and in a Genetically Modified Intestinal Cancer Mouse Model.

Gasdermin E (GSDME), also known as deafness autosomal dominant 5 (DFNA5) and previously identified to be an inducer of regulated cell death, is frequently epigenetically inactivated in different cancer types, suggesting that GSDME is a tumor suppressor gene. In this study, we aimed to evaluate the tumor-suppressive effects of GSDME in two intestinal cancer mouse models. To mimic the silencing of GSDME by methylation as observed in human cancers, a Gsdme knockout (KO) mouse was developed. The effect of GSDME on tumorigenesis was studied both in a chemically induced and in a genetic intestinal cancer mouse model, as strong evidence shows that GSDME plays a role in human colorectal cancer and representative mouse models for intestinal cancer are available. Azoxymethane (AOM) was used to induce colorectal tumors in the chemically induced intestinal cancer model (n = 100). For the genetic intestinal cancer model, Apc1638N/+ mice were used (n = 37). In both experiments, the number of mice bearing microscopic proliferative lesions, the number and type of lesions per mouse and the histopathological features of the adenocarcinomas were compared between Gsdme KO and wild type (WT) mice. Unfortunately, we found no major differences between Gsdme KO and WT mice, neither for the number of affected mice nor for the multiplicity of proliferative lesions in the mice. However, recent breakthroughs on gasdermin function indicate that GSDME is an executioner of necrotic cell death. Therefore, it is possible that GSDME may be important for creating an inflammatory microenvironment around the tumor. This is in line with the trend towards more severe inflammation in WT compared to Gsdme KO mice, that we observed in our study. We conclude that the effect of GSDME in tumor biology is probably more subtle than previously thought.

Methylation analysis of Gasdermin E shows great promise as a biomarker for colorectal cancer.

In addition to its implication in hereditary hearing loss, the Gasdermin E (GSDME) gene is also a tumor suppressor involved in cancer progression through programmed cell death. GSDME epigenetic silencing through methylation has been shown in some cancer types, but studies are yet to fully explore its diagnostic/prognostic potential in colorectal cancer on a large-scale. We used public data from The Cancer Genome Atlas (TCGA) to investigate differences in GSDME methylation and expression between colorectal cancer and normal colorectal tissue, and between left- and right-sided colorectal cancers in 432 samples. We also explored GSDME's diagnostic capacity as a biomarker for colorectal cancer. We observed differential methylation in all 22 GSDME CpGs between tumor and normal tissues, and in 18 CpGs between the left- and right-sided groups. In the cancer tissue, putative promoter probes were hypermethylated and gene body probes were hypomethylated, while this pattern was inversed in normal tissues. Both putative promoter and gene body CpGs correlated well together but formed distinct methylation patterns with the putative promoter exhibiting the most pronounced methylation differences between tumor and normal tissues. Clinicopathological parameters, excluding age, did not show any effect on CpG methylation. Although the methylation of 5 distinct probes was a good predictor of gene expression, we could not identify an association between GSDME methylation and expression in general. Survival analysis showed no association between GSDME methylation and expression on 5-year patient survival. Through logistic regression, we identified a combination of 2 CpGs, that can discriminate between cancer and normal tissue with high accuracy (AUC = 0.95) irrespective of age and tumor stage. We also validated our model in 3 external methylation datasets, from the Gene Expression Omnibus database, and similar results were reached. Our results suggest that GSDME is a promising biomarker for the detection of colorectal cancer.

Large-scale analysis of DFNA5 methylation reveals its potential as biomarker for breast cancer.

Background: Breast cancer is the most frequent cancer among women worldwide. Biomarkers for early detection and prognosis of these patients are needed. We hypothesized that deafness, autosomal dominant 5 (DFNA5) may be a valuable biomarker, based upon strong indications for its role as tumor suppressor gene and its function in regulated cell death. In this study, we aimed to analyze DFNA5 methylation and expression in the largest breast cancer cohort to date using publicly available data from TCGA, in order to further unravel the role of DFNA5 as detection and/or prognostic marker in breast cancer. We analyzed Infinium HumanMethylation450k data, covering 22 different CpGs in the DFNA5 gene (668 breast adenocarcinomas and 85 normal breast samples) and DFNA5 expression (Agilent 244K Custom Gene Expression: 476 breast adenocarcinomas and 56 normal breast samples; RNA-sequencing: 666 breast adenocarcinomas and 71 normal breast samples). Results: DFNA5 methylation and expression were significantly different between breast cancer and normal breast samples. Overall, breast cancer samples showed higher DFNA5 methylation in the putative gene promoter compared to normal breast samples, whereas in the gene body and upstream of the putative gene promoter, the opposite is true. Furthermore, DFNA5 methylation, in 10 out of 22 CpGs, and expression were significantly higher in lobular compared to ductal breast cancers. An important result of this study was the identification of a combination of one CpG in the gene promoter (CpG07504598) and one CpG in the gene body (CpG12922093) of DFNA5, which was able to discriminate between breast cancer and normal breast samples (AUC = 0.93). This model was externally validated in three independent datasets. Moreover, we showed that estrogen receptor state is associated with DFNA5 methylation and expression. Finally, we were able to find a significant effect of DFNA5 gene body methylation on a 5-year overall survival time. Conclusions: We conclude that DFNA5 methylation shows strong potential as detection and prognostic biomarker for breast cancer.

DFNA5 promoter methylation a marker for breast tumorigenesis.

BACKGROUND: Identification of methylation markers that are sensitive and specific for breast cancer may improve early detection. We hypothesize that DFNA5 promoter methylation can be a valuable epigenetic biomarker, based upon strong indications for its role as tumor suppressor gene and its function in regulated cell death. RESULTS: Statistically different levels of methylation were seen, with always very low levels in healthy breast reduction samples, very high levels in part of the adenocarcinoma samples and slightly increased levels in part of the normal tissue samples adjacent the tumor. One of the CpGs (CpG4) showed the best differentiation. A ROC curve for DFNA5 CpG4 methylation showed a sensitivity of 61.8% for the detection of breast cancer with a specificity of 100%. MATERIALS AND METHODS: We performed methylation analysis on four CpGs in the DFNA5 promoter region by bisulfite pyrosequencing on 123 primary breast adenocarcinomas and 24 healthy breast reductions. For 16 primary tumors, corresponding histological normal tissue adjacent to the tumor was available. CONCLUSIONS: We conclude that DFNA5 methylation shows strong potential as a biomarker for detection of breast cancer. Slightly increased methylation in histologically normal breast tissue surrounding the tumor suggests that it may be a good early detection marker.

Expression profiling of migrated and invaded breast cancer cells predicts early metastatic relapse and reveals Krüppel-like factor 9 as a potential suppressor of invasive growth in breast cancer.

Cell motility and invasion initiate metastasis. However, only a subpopulation of cancer cells within a tumor will ultimately become invasive. Due to this stochastic and transient nature, in an experimental setting, migrating and invading cells need to be isolated from the general population in order to study the gene expression profiles linked to these processes. This report describes microarray analysis on RNA derived from migrated or invaded subpopulations of triple negative breast cancer cells in a Transwell set-up, at two different time points during motility and invasion, pre-determined as "early" and "late" in real-time kinetic assessments. Invasion- and migration-related gene expression signatures were generated through comparison with non-invasive cells, remaining at the upper side of the Transwell membranes. Late-phase signatures of both invasion and migration indicated poor prognosis in a series of breast cancer data sets. Furthermore, evaluation of the genes constituting the prognostic invasion-related gene signature revealed Krüppel-like factor 9 (KLF9) as a putative suppressor of invasive growth in breast cancer. Next to loss in invasive vs non-invasive cell lines, KLF9 also showed significantly lower expression levels in the "early" invasive cell population, in several public expression data sets and in clinical breast cancer samples when compared to normal tissue. Overexpression of EGFP-KLF9 fusion protein significantly altered morphology and blocked invasion and growth of MDA-MB-231 cells in vitro. In addition, KLF9 expression correlated inversely with mitotic activity in clinical samples, indicating anti-proliferative effects.