Stage Triple Negative Breast Cancer Research Articles

The increased antioxidant action of HDL is independent of HDL cholesterol plasma levels in triple-negative breast cancer.

The association between high-density lipoprotein cholesterol (HDLc) with the incidence and progression of breast cancer (BC) is controversial. HDL removes excess cholesterol from cells and acts as an antioxidant and anti-inflammatory. BC is a heterogeneous disease, and its molecular classification is important in the prediction of clinical and therapeutic evolution. Triple-negative breast cancer (TNBC) presents higher malignancy, lower therapeutic response, and survival rate. In the present investigation, the composition and antioxidant activity of isolated HDL was assessed in women with TNBC compared to controls. Twenty-seven women with a recent diagnosis of TNBC, without prior treatment, and 27 healthy women (control group) paired by age and body mass index (BMI) were included in the study. HDL and low-density lipoprotein (LDL) were isolated from plasma by discontinuous density gradient ultracentrifugation. Plasma lipid profile and HDL composition (total cholesterol, TC; triglycerides, TG; HDLc; phospholipids, PL) were determined by enzymatic colorimetric methods. ApoB and apo A-I were quantified by immunoturbidimetry. The antioxidant activity of HDL was determined by measuring the lag time phase for LDL oxidation and the maximal rate of conjugated dienes formation in LDL incubated with copper sulfate solution. The absorbance (234 nm) was monitored at 37°C, for 4 h, at 3 min intervals. The control group was similar to the TNBC concerning menopausal status, concentrations, and ratios of plasma lipids. The composition of the HDL particle in TC, TG, PL, and apo A-I was also similar between the groups. The ability of HDL to retard LDL oxidation was 22% greater in the TNBC group as compared to the control and positively correlated with apoA-I in HDL. Moreover, the antioxidant activity of HDL was greater in the advanced stages of TNBC (stages III and IV) compared to the control group. The maximum rate of formation of conjugated dienes was similar between groups and the clinical stages of the disease. The results highlight the role of HDL as an antioxidant defense in TNBC independently of HDLc plasma levels. The improved antioxidant activity of HDL, reflected by retardation in LDL oxidation, could contribute to limiting oxidative and inflammatory stress in advanced stages of TNBC.

Abstract P3-03-19: Real-world data of clinical characteristics, risk factors and outcomes of Chilean triple-negative breast cancer patients

Abstract Background: triple-negative breast cancer (TNBC) is associated with hereditary and environmental risk factors plus an overall worse prognosis compared to other Breast Cancer (BC) subtypes. While TNBC risk factors, prevalence, clinical characteristics and prognosis may vary throughout different populations, limited data on Latin American patients forces clinical decisions to be based predominantly on data coming from non-Hispanic women. To obtain local epidemiological information, regarding risk factors and clinical outcomes, we analysed the largest Chilean BC registry. Methods: we conducted a retrospective population-cohort study involving females with any stage TNBC, treated at a community hospital (mid-low income) and at an academic private hospital (high income), between the years 2010 and 2021. Risk factors, reason for consultation, clinical and pathological characteristics and prognosis were separately analysed for both TNBC and non-TNBC subgroups. Univariate and multivariate analyses were performed to identify prognostic factors for survival on TNBC patients. Results: From 5,806 patients, 647 (11.2%) were identified as TNBC. Compared to non-TNBC patients, women were younger (median age 55.2 vs. 57.2, p=0.0001), with 15.8% of TNBC patients having been diagnosed before the age of 40 compared to 9.6% in non-TNBC (p= 0.0001). TNBC had a significantly lower screen-detected cancer rate (14.5% vs. 31.6% p= 0.0001) and worse stage at diagnosis. No differences were seen between patients seen at a community hospital and private centre, for both TNBC rate and stage. Other risk factors such as parity, age at first gestation, menarche, hormone therapy replacement and obesity showed no significant differences between TNBC and no-TNBC patients (table 1). With a median follow up of 57 months, 5-year overall survival (OS) and BC specific death were significantly shorter for TNBC compared to non-TNBC (76.4% vs 88.1% and 78.9% vs 91.2%, respectively; p=0.0001) (table 2). In the multivariate analysis, TN subtype (HR=2.3, p=0.0001), stage (HR=2.05 for stage II vs stage I, HR=7.04 for stage III vs. stage I, p=0.0001), lower income (HR= 1.64, p=0.0001), and non-screened detected BC (HR=1.32, p=0.03) were all associated with worse overall survival (table 3). Conclusion: This is the first study focusing on TNBC characteristics in Chilean BC patients and to our knowledge, the largest performed in a Latin American population. We identified a lower proportion of TNBC patients when compared with data reported from other LA groups and worldwide, a very low screen detected cancer rate and as expected significantly lower TNBC survival rate compared to non-TNBC women. While TNBC patients were younger compared to the non-TNBC group, this age difference was marginal compared to other reported studies. Community hospital patients (with mid-low income) were associated with lower survival rates for both all-cause mortality and BC specific survival, regardless of a similar stage distribution at diagnosis. Reflecting an underlying interaction between social and biological factors that needs to be addressed. Table 1. Patient characteristics: Triple-negative versus noN-triple negative breast cancer BMI: Body mass index; FH: Family history * Difference is statistically significant. Table 2. Survival comparison in triple-negative versus non-triple negative breast cancer * Difference is statistically significant. Table 3. Cox Regression Multivariate analysis * Difference is statistically significant. Citation Format: Benjamin Walbaum, FRANCISCO ACEVEDO, Catherine Bauerle, Mauricio Camus, Manuel Manzor, Raul Martinez, Paulina Veglia, Marisel Navarro, Constanza Guerra, Francisco Dominguez, Tomas Merino, Lidia Medina, CÉSAR SÁNCHEZ. Real-world data of clinical characteristics, risk factors and outcomes of Chilean triple-negative breast cancer patients [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P3-03-19.

Abstract P6-01-13: Identification of Protein Biomarkers for Early Detection and Stratification of Triple Negative Breast Cancer

Abstract Breast cancer (BC) is the most frequent malignancy in women worldwide. Breast cancer affects roughly 3,000,000 people worldwide, with triple negative breast cancer (TNBC) accounting for 10-15% of all cases. In comparison to other types of breast cancer, TNBC stands out for its heterogenies disease, poor prognosis and aggressive behaviour. In the early stages of TNBC, neoadjuvant chemotherapy (NAC), which is given to the patient before surgery, has been considered a viable treatment strategy. Pathological complete response (pCR), which has been shown to increase estimates of disease-free (the amount of time following treatment during which there are no signs of malignancy), distant recurrence-free (the cancer has spread to far-off regions of the body) and overall survival, has been linked to NAC in 30% of patients. The objective of this study was to apply mass-spectrometry-based proteomics to serum samples from TNBC patients who have received NAC to identify i) biomarkers that might predict response to NAC, ii) biomarkers that might correlate with the extent of residual disease. These biomarkers will potentially inform treatment decisions such as the escalation/de-escalation of chemotherapy dosage for early TNBC patients. In this study, two proteomic approaches have been used to identify and measure protein candidate biomarkers: un-biased LC-MS/MS and targeted proteomics respectively. The discovery approach led to the identification of 17 unique proteins and 118 unique peptides that were differently expressed. The developing of a multiple reaction monitoring (MRM) assay for biomarker evaluation will be based on the prioritization of the potential signature proteins and other proteins obtained from public resources. Subject to successful evaluation and subsequent validation the candidate biomarkers may be beneficial for identifying TNBC patients who will achieve residual disease after NAC. Citation Format: Essraa metwali, Stephen Pennington. Identification of Protein Biomarkers for Early Detection and Stratification of Triple Negative Breast Cancer [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P6-01-13.

Abstract P4-06-11: Pathologic Complete Response in Triple Negative Breast Cancer of Black vs White Patients in the Post-Keynote 522 Era

Abstract Pathologic Complete Response in Triple Negative Breast Cancer of Black vs White Patients in the Post-Keynote 522 Era Melanie Sheen MD, Victoria Chung DO, Ruby Maini MD, Michael Duggan BS, Julia Levy BS Background Triple-negative breast cancer (TNBC) is an aggressive form of breast cancer that lacks estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER-2) gene amplification. Women with TNBC have worse survival outcomes and increased rates of relapse and distant metastasis as compared to women with non-TNBC. Treatment of TNBC has recently been focused on neoadjuvant chemotherapy (NACT) with a goal of achieving a pathologic complete response (pCR) which is associated with longer event-free survival and overall survival. The KEYNOTE-522 trial was presented at the San Antonio Breast Cancer Symposium in December 2019 and found that patients who received pembrolizumab, an anti–programmed death 1 (PD-1) monoclonal antibody, plus NACT were more likely to achieve pCR than women who received placebo plus NACT. On July 26, 2021, the FDA approved the use of pembrolizumab in combination with NACT for high risk, early stage TNBC. KEYNOTE-522 did not collect race as a baseline demographic characteristic, and since TNBC disproportionately affects younger women and Black women, confirming the efficacy of achieving pCR in these groups is essential. Further investigation of the factors that may contribute to achieving pCR in women treated with pembrolizumab for TNBC is warranted. We set out to perform a retrospective analysis examining the rates of pCR in Black versus White patients with TNBC since the initial revelation of the KEYNOTE-522 data. Methods This retrospective chart review of a regional health care network included patients who had been diagnosed with Stage II/III TNBC, documented race as Black/African-American or White, and received treatment with pembrolizumab in the NACT setting. Exclusion criteria included ER-positivity, PR-positivity, HER2-positivity, or unknown receptor status, no pembrolizumab in the neoadjuvant setting, absence of documented race, and age < 18 years-old. Data was collected using Epic SlicerDicer program. Results 118 patients met inclusion criteria. 59 (50.0%) were Black/African American, 59 (50.0%) were white. There were 57 (48.3%) patients who had pCR status identified through pathology reports while the remaining 61 (51.7%) are still undergoing NACT awaiting surgery. 34 Black women and 17 white women have not had surgery yet. Of women who underwent surgery, 12 Black women achieved pCR compared to 15 White women. 13 Black women and 16 White women did not have pCR Discussion Analysis of the data demonstrates an equal number of Black and White women receiving NACT with pembrolizumab. Of those women, there was relatively equal number of pCR between Black and White women. This data shows no appreciable difference in outcomes of Black and White women in terms of response to therapy. Conclusion Given the known association of pCR with increased survival, pembrolizumab should be considered in the treatment regimen for both Black and White women with stage II/III TNBC. This retrospective study is limited by a small patient population. Continued data collection is underway and will be updated. Citation Format: Melanie Sheen, Victoria Chung, Ruby Maini, Michael Duggan, Julia Levy. Pathologic Complete Response in Triple Negative Breast Cancer of Black vs White Patients in the Post-Keynote 522 Era [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P4-06-11.

Abstract HER2-01: HER2-01 Clinical and Molecular Characteristics of HER2-low/zero Early Stage Triple-Negative Breast Cancer

Abstract Background: In the metastatic setting, low HER2 expression is associated with clinical benefit from trastuzumab deruxtecan, a HER2-targeting antibody drug conjugates. However, little is known about the biological significance of low HER2 expression in patients with early stage triple-negative breast cancer (TNBC) receiving neoadjuvant therapy (NAT). Methods: Out of 595 patients with stage I-III TNBC enrolled on the prospective ARTEMIS trial (NCT02276443) from 2015-2021, we identified 367 patients with available HER2 immunohistochemistry (IHC) results on pre-NAT tumor tissue (HER2-zero: n=218; HER2-low [IHC 1+, 2+]: n=149). All patients were treated with anthracycline-based NAT. In cases where sufficient pre-NAT tumor tissue were available, additional IHC and/or RNAseq were performed. Differential gene expression (DGE) and pathway analysis were performed using DEseq2. Gene set enrichment analysis (GSEA) was performed using the Hallmark gene sets. Deconvolution analyses were performed using CIBERSORT. We controlled for multiple hypothesis using a false discovery rate (FDR) threshold with the Benjamini-Hochberg method, accepting as significant genes with at least a 2-fold change and < 5% FDR. Results: Table 1 summarizes baseline clinicopathological features of the 367 patients. Compared to HER2-zero tumors, HER2-low tumors were less likely of metaplastic histology (p=0.001), associated with lower Ki67 (p=0.017) and were more likely to be androgen receptor (AR)-positive (p=0.01). There were no significant differences in tumor-infiltrating lymphocytes (TILs) infiltration and PD-L1 expression between HER2-zero and HER2-low tumors. Among the 226 patients with sufficient pre-NAT tissue for RNAseq, DGE analyses demonstrated upregulation of genes involved in fatty acid metabolism (ACSM1) and steroid hormone metabolism (DHRS2, UGT2B28) in HER2-low tumors compared with HER2-zero tumors. Deconvolution analyses revealed no significant differences between predicted proportions of immune cell subpopulations between HER2-low and HER2-zero tumors. Although rates of pCR were not significantly different between patients with HER2-zero (46%) and HER2-low tumors (40%) (p=0.34), non-pCR in patients with HER2-low tumors was associated with increased expression of EREG, which encodes an EGFR ligand, while non-pCR in patients with HER2-zero tumors was associated with downregulation in genes involved in immune response pathways. GSEA further identified the Hallmark allograft rejection (FDR q=0.001), interferon gamma response (FDR q=0.002), and interferon alpha response pathways (FDR q=0.007) as the 3 most significantly downregulated pathways in HER2-zero tumors from patients experiencing a non-pCR relative to HER2-zero tumors from patients experiencing a pCR. Conclusion: In early stage TNBC, low HER2 expression is associated with increased AR expression and upregulation of genes associated with fatty acid and steroid hormone metabolism. Gene expression analyses suggest that drivers of resistance to NAT differ between HER2-low and HER2-zero tumors. Biological differences between HER2-zero and HER2-low tumors exist and may influence future personalized treatment for patients with early stage TNBC. Citation Format: Clinton Yam, Ziyi Li, Anil Korkut, Wencai Ma, Elisabeth Kong, Holly A. Hill, Hussein Abbas, Sausan Abouharb, Beatriz Adrada, Banu K. Arun, Carlos H. Barcenas, Ajit Bisen, Daniel Booser, Aman Buzdar, Rosalind Candelaria, Junjie Chen, Alyson Clayborn, Senthil Damodaran, Qingqing Ding, Haven Garber, Gabriel N. Hortobagyi, Kelly K. Hunt, Nuhad K. Ibrahim, Adaeze Iheme, Meghan S. Karuturi, Kimberly Koenig, Rachel M. Layman, Jangsoon Lee, Jennifer K. Litton, Melissa Mitchell, Giancarlo Moscol, Jason Mouabbi, Rashmi K. Murthy, Oluchi Oke, Paula Pohlmann, David Ramirez, Elizabeth Ravenberg, Sadia Saleem, Mediget Teshome, Vicente Valero, Jason White, Madison Williams, Wendy Woodward, Chasity Yajima, Naoto T. Ueno, Ken Chen, Gaiane Rauch, Lei Huo, Debu Tripathy. HER2-01 Clinical and Molecular Characteristics of HER2-low/zero Early Stage Triple-Negative Breast Cancer [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr HER2-01.

Abstract OT2-10-02: Phase I trial of an alpha-lactalbumin vaccine in patients with operable triple-negative breast cancer (TNBC)

Abstract Background: Triple-negative breast cancer (TNBC) is the subtype of breast cancer with the worst prognosis and is the subtype most often associated with germline mutations of BRCA1 as well as other genes. Alpha-lactalbumin (aLA) is a milk protein expressed in lactating breasts but not at other times or in other normal tissues. Expression of aLA is found in approximately 70% of TNBC (Cancers PMID: 27322324) so is an attractive immunologic target for TNBC based on the “retired protein hypothesis” (Semin Immunol PMID: 31926646). Pre-clinical studies have shown that vaccination with aLA inhibits the growth of established breast tumors and provides potent protection from development of autochthonous tumors in transgenic murine models of breast cancer and against 4T1 transplantable breast cancer in BALB/c mice (Nat Med PMID: 20512124). Specific Aims: We are conducting a Phase I trial of vaccination with an aLA vaccine in patients with early stage TNBC to demonstrate the safety of this approach and to document the ability to produce a relevant immunologic response to aLA. Trial Design: Patients are being entered into a Phase I trial of alpha-lactalbumin with GMP-grade zymosan adjuvant in Montanide ISA 51 VG vehicle. Subjects receive a total of 3 vaccinations administered once every 2 weeks. Toxic events of Common Terminology Criteria for Adverse Events (CTCAE) grade 2 or greater are considered dose-limiting. Dose levels being tested in the current protocol are alpha-lactalbumin/zymosan 0.01/0.01, 0.1/0.01, 0.5/0.01, 0.5/0.03, and 0.5 mg/0.06 mg. Patients are being monitored for toxicity until 84 days after the first vaccination or resolution of toxicity, whichever is later. Blood is being drawn prior to therapy and 14, 28, and 56 days after the first vaccination to assess cellular response using enzyme-linked immunosorbent spot (ELISpot) assays of interferon-gamma and interleukin-17 production in response to aLA. Humoral response to aLA vaccination is being assessed by enzyme-linked immunosorbent assay (ELISA). Eligibility Criteria: Patients with ER-negative, PR-negative, HER2-negative breast cancer of pathologic stage II-III or who had residual disease after standard pre-operative systemic therapy. Participants must be within 3 years of initiation of treatment and have no evidence of recurrence. Dose Selection: Doses are being escalated using a 3+3 trial design to determine the maximum tolerated dose, the lowest immunologic dose and the optimal immunologic dose Present Accrual and Target Accrual: Dependent on toxicity, 18-30 patients will be treated. Future Plans and Contact Information: After identification of the maximum tolerated dose and expansion of the dose levels associated with effective tumor immunity we plan to enroll 2 additional cohorts of patients: 1) patients who have completed pre-operative chemo-immunotherapy and are receiving pembrolizumab as standard of care therapy, and 2) patients without cancer planning to undergo prophylactic bilateral mastectomy. Interested parties may contact Dr. Budd at buddg@ccf.org. Funding Source: Department of Defense (W81XWH-17-1-0592 and W81XWH-17-1-0593) Citation Format: George Budd, Justin M. Johnson, Emily Rhoades, Halle Moore, Megan L. Kruse, Erin Roesch, Jame Abraham, Brenna Elliott, Elena Haury, Vincent K. Tuohy. Phase I trial of an alpha-lactalbumin vaccine in patients with operable triple-negative breast cancer (TNBC) [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr OT2-10-02.

Abstract PD15-06: PD15-06 Pathologic complete response and breast-conserving surgery are associated with improved prognosis in patients with early-stage triple-negative breast cancer treated with neoadjuvant chemotherapy

Abstract Background: Neoadjuvant chemotherapy (NACT) is standard of care for patients with triple-negative breast cancer (TNBC). Treatment response, especially pathologic complete response (pCR), is a strong predictive factor for treatment outcome. In the setting of up-front surgery, retrospective data have suggested improved outcome in patients with early TNBC that received breast-conserving surgery with adjuvant radiotherapy (BCT) as compared to mastectomy. Methods: We identified 2632 patients with early TNBC from the German Breast Group meta-database. Patients with cT1-2 cN0 and ypN0, available surgery and follow-up data were eligible for this project. A total of 1074 patients from 8 prospective NACT trials were analyzed. Endpoints of interest were locoregional recurrence as first site of relapse (LRR, other sites of recurrence were considered competing events), disease-free survival (DFS) and overall survival (OS); analyses were performed using univariate and multivariate Fine-Gray (for LRR) and Cox models including study, age, cT, surgery type and pCR. For the analyses including pCR as covariable, only patients at risk at the landmark time were evaluated. Results: Median age was 48 years, 69.6% of patients had cT2 tumors and 85.3% underwent BCS. Of the 1074 analyzed patients, 48.8% achieved pCR. After a median follow-up of 64 months, there were 94 (8.8%) locoregional events as first site of relapse. Upon univariate analysis, absence of pCR (hazard ratio [HR]=2.28; 95%CI 1.44-3.61; p< 0.001) and ypT-stage (ypT0/is vs. ypT1-3, HR=0.61; 95%CI 0.40-0.95; p=0.028) were significantly associated with LRR, while type of surgery, age and cT-stage were not. Upon multivariate analysis, absence of pCR was the only factor associated with increased risk of LRR (HR=2.22; 95%CI 1.38-3.58; p=0.001). Patients that underwent mastectomy (N=158) were significantly younger (age ≤ 50 years 72.8% vs. 59.9% for BCT [N=916]; p=0.002) DFS and OS was significantly better in patients who underwent BCT compared to mastectomy (DFS: HR=0.47; 95%CI 0.34-0.66; p< 0.001 and OS: HR=0.40; 95%CI 0.26-0.63; p< 0.001). In multivariate analysis, BCT was associated with a significantly better DFS and OS as compared to mastectomy (DFS: HR=0.51; 95%CI 0.36-0.72; p< 0.001; and OS HR=0.43; 95%CI 0.27-0.68; p< 0.001), whereas absence of pCR was associated with significantly worse DFS and OS (DFS: HR=2.43; 95%CI 1.78-3.31; p< 0.001; and OS: HR=3.15; 95%CI 1.94-5.10; p< 0.001). Conclusions: In this retrospective analysis from the GBG meta-database, treatment response, e.g. pCR, was the main determinant of locoregional recurrence in patients with early stage TNBC treated with NACT. BCT was associated with improved DFS and OS compared to mastectomy, which may at least in part reflect favorable patient selection. Citation Format: David Krug, Valentina Vladimirova, Michael Untch, Thorsten Kühn, Andreas Schneeweiss, Carsten Denkert, Beyhan Ataseven, Christine Solbach, Bernd Gerber, Hans Tesch, Michael Golatta, Sabine Seiler, Jörg Heil, Valentina Nekljudova, Sibylle Loibl. PD15-06 Pathologic complete response and breast-conserving surgery are associated with improved prognosis in patients with early-stage triple-negative breast cancer treated with neoadjuvant chemotherapy [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr PD15-06.

Abstract P2-11-25: A 10-gene signature to predict the prognosis of early-stage triple-negative breast cancer

Abstract Background: Triple-negative breast cancer (TNBC) is highly heterogeneous cancer and the most challenging subtype of breast cancer. And its prognosis is poor compared to the other subtypes. Unlike luminal type cancers, there is no valid biomarker to predict the prognosis of patients with early TNBC. To establish an elaborate therapeutic strategy for TNBC, biomarkers that accurately predict the prognosis and response to treatment are needed. Method: 184 patients with early stage TNBC (training cohort, n = 76; validation cohort, n = 108) were enrolled. Median Follow-up period was 51.5 months (range: 4.6-230.8) for training cohort and 58.3 months (range: 6.6-99.8) for validation cohort. Of the patients in training cohort, 13 patients had recurrence or metastasis. Of the patients in validation cohort, 23 patients had recurrence or metastasis. Using a HiSeq sequencer, RNA sequencing was conducted to analyze the gene expression profiles of tumor samples from TNBC patients. Gene signature was analyzed by combination of DEGs which found in gene expression profiles. Cross validation and meta-analysis were conducted as pre-validation. Meta-analysis was conducted using CBS probePINGS. To compare gene signature and other methods, PAM 50 call and TCR diversity analysis were investigated. Statistical analyses were conducted using R language (v.3.4.3). Result: To predict prognosis of recurrence or metastasis for TNBC patients, we identified the 10-gene signature (DGKH, GADD45B, KLF7, LYST, NR6A1, PYCARD, ROBO1, SLC22A20P, SLC24A3 and SLC45A4) that stratified patients with TNBC by risk score (sensitivity = 92.31%; specificity = 92.06%; accuracy = 92.11%) and validated in a cohort of separate institutions. Meta-analysis supported the biological relevance of the 10-gene signature to well-known driving pathways in TNBC. When compared with other potential biomarkers like PAM 50 call and T-cell receptor β diversity, the 10-gene signature was the only independent factor that can predict prognosis for invasive disease-free survival in multivariate analysis. Conclusion: Our novel findings can contribute to solving the diagnostic challenges in TNBC and the 10-gene signature may serve as a novel biomarker for risk-based patient care. Citation Format: Chang Min Kim, Kyong Hwa Park, Yun Suk Yu, Ju Won Kim, Jin Young Park, Jeong Eon Lee, Sung Hoon Sim, Bo Kyoung Seo, Jin Kyeoung Kim, Eun Sook Lee, Yeon Hee Park, Sun-Young Kong. A 10-gene signature to predict the prognosis of early-stage triple-negative breast cancer [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P2-11-25.

Construction and validation of a macrophage polarization-related prognostic index to predict the overall survival in patients with early-stage triple-negative breast cancer.

Triple-negative breast cancer (TNBC) is a highly heterogeneous disease and the current prognostic system cannot meet the clinical need. Interactions between immune responsiveness and tumor cells plays a key role in the progression of TNBC and macrophages are vital component of immune cells. A prognostic model based on macrophages may have great accuracy and clinical utility. For model development, we screened early stage (without metastasis) TNBC patients from The Cancer Genome Atlas (TCGA) database. We extracted messenger RNA (mRNA) expression data and clinical data including age, race, tumor size, lymph node status and tumor stage. The follow up time and vital status were also retrieved for overall survival calculation. Cell-type Identification by Estimating Relative Subsets of RNA Transcripts (CIBERSORT) was used to calculate the immune cell composition of each sample. Weighted gene co-expression network analysis (WGCNA) was used to identify M1-like macrophage-related genes. Combining least absolute shrinkage and selection operator (LASSO) with multivariate Cox regression, the M1-like macrophage polarization-related prognostic index (MRPI) was established. We obtained TNBC patients in Gene Expression Omnibus (GEO) database through PAM50 method and retrieved the mRNA expression data and survival data. The Harrell's concordance index (CI), the area under the receiver operating characteristic (ROC) curves (AUCs) and the calibration curve were used to evaluate the developed model. We obtained 166 early TNBC cases and 113 normal tissue cases for model building, along with 76 samples from GSE58812 cohort for model validation. CIBERSORT analysis suggested obvious infiltration of macrophages, especially M1-like macrophages in early TNBC. Four genes were eventually identified for the construction of MPRI in the training set. The AUCs at 2 years, 3 years, and 5 years in the training cohort were 0.855, 0.881 and 0.893, respectively; and the AUCs at 2 years, 3 years, and 5 years in the validation cohort were 0.887, 0.792 and 0.722, respectively. Calibration curves indicated good predictive ability and high consistency of our model. MRPI is a promising biomarker for predicting the prognosis of early-stage TNBC, which may indicate personalized treatment and follow-up strategies and thus may improve the prognosis.

THE EFFECT OF TOPOISOMERASE ІІ ALPHA ON THE RESPONSE TO NEOADJUVANT CHEMOTHERAPY OF TRIPLE-NEGATIVE BREAST CANCER

Summary. Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer associated with poor prognosis, lacks of standard biomarkers and tumor heterogeneity. So it is the lack of therapeutic biomarkers and tumor heterogeneity are the main causes of therapeutic resistance in the case of TNBC. Differences in tumor cell properties are provides by enzymes that are important potential therapeutic targets. This is makes the exploring of prognostic biomarkers and potential therapeutic targets of TNBC an important area of research. Aim: to improve treatment outcomes for patients with TNBC by evaluating topoisomerase 2 alpha as a potential predictive marker of treatment efficacy. Objects and methods: the study involved 45 patients with II-III stages of TNBC. In addition to standard biomarkers, the level of topoisomerase II alpha expression was determined by the immunohistochemistry. Instrumental methods of diagnosis, pathomorphological and immunohistochemistry, as well as statistical methods of evaluating the obtained data were used in the study. Results: the taxane-containing chemotherapy regimens in patients with TNBC increases the response to treatment. Topoisomerase II alpha overexpression is associated with better prognosis and response to treatment in patients with TNBC. Conclusions: the main results of study allow us to consider topoisomerase II alpha as a prognostically valuable marker for predicting the course of the disease and the response to chemotherapy, as well as the advantage of taxane-containing treatment regimens in patients with TNBC.

Antibody-drug conjugates targeting TROP-2: Clinical development in metastatic breast cancer

Antibody drug conjugates (ADCs) combine the potent cytotoxicity of chemotherapy with the antigen -specific targeted approach of antibodies into one single molecule. Trophoblast cell surface antigen 2 (TROP-2) is a transmembrane glycoprotein involved in calcium signal transduction and is expressed in multiple tumor types. TROP-2 expression is higher in HER2-negative breast tumors (HR+/HR-) and is associated with worse survival. Sacituzumab govitecan (SG) is a first-in-class TROP-2-directed ADC with an anti-TROP-2 antibody conjugated to SN-38, a topoisomerase inhibitor via a hydrolysable linker. This hydrolysable linker permits intracellular and extracellular release of the membrane permeable payload enabling the “bystander effect” contributing to the efficacy of this agent. There was significant improvement in progression free survival (PFS) and overall survival (OS) with SG versus chemotherapy in pretreated metastatic triple negative breast cancer (TNBC), resulting in regulatory approval. Common adverse events (AE) reported were neutropenia and diarrhea. SG also demonstrated clinical activity versus chemotherapy in a phase III trial of HR+/HER2-metastatic breast cancer (MBC) and is under evaluation in first-line metastatic and early stage TNBC as well. Datopotamab deruxtecan (Dato-DXd) is a TROP-2 ADC that differs from SG in that it has a cleavable tetrapeptide linker and a more potent topoisomerase inhibitor payload. This construct is highly stable in circulation with a longer half-life than SG, and undergoes cleavage in presence of intracellular lysosomal proteases. Dato-DXd demonstrated preliminary efficacy in unselected metastatic TNBC, with common AEs of low-grade nausea and stomatitis. Dato-DXd is being investigated in phase III studies in metastatic TNBC and HR+/HER2- MBC. These novel TROP-2 ADCs have the potential to deliver enhanced efficacy with reduced toxicity in MBC and possibly in early stage breast cancer (EBC).

Are we overtreating stage I triple-negative breast cancer in Ontario? A population-based retrospective epidemiological analysis using the ICES database.

Triple-negative breast cancer (TNBC) is associated with inferior outcomes. The use of adjuvant chemotherapy is the mainstay of treatment, and its efficacy was demonstrated to be correlated with tumor size. Different guidelines exist regarding chemotherapy in early-stage TNBC. This study uses ICES database to examine the outcomes of the use of adjuvant chemotherapy in stage I TNBC in Ontario stratified by tumor size. Records of TNBC patients diagnosed in 2012 to 2014 were collected from ICES database. Stage I patients were analyzed by tumor size: T1a (≤ 0.5cm), T1b (> 0.5cm and ≤ 1.0cm), and T1c (> 1.0cm and ≤ 2.0cm). Kaplan-Meier curves, log-rank test statistic, and Cox's proportional hazard regression were used to compare differences in overall survival (OS) between chemotherapy and no-chemotherapy groups. Of 610 patients, 183 had tumor sizes ≤ 1cm, representing stages T1aN0M0 and T1bN0M0, and 427 had tumors > 1cm to 2cm, representing stage T1cN0M0. Patients with tumors ≤ 1cm who received chemotherapy did not have a significant difference in OS compared to the no-chemotherapy group (p = 0.41, hazard ratio (HR) 0.40, 95% confidence interval (CI) 0.021-2.5). However, patients with tumor sizes > 1cm to 2cm who received chemotherapy demonstrated significantly better OS compared to those without (p = 0.023, HR = 0.40, 95% CI 0.16-0.86). Patients with TNBC stage T1cN0M0 should receive adjuvant chemotherapy. For TNBC tumors ≤ 1cm, avoidance of chemotherapy can be considered. Prospective research should further investigate the efficacy of chemotherapy in TNBC stages T1a-bN0M0.Trial Registration University of Windsor REB#16-119.

LBA13 Nivolumab and ipilimumab in early-stage triple negative breast cancer (TNBC) with tumor-infiltrating lymphocytes (TILs): First results from the BELLINI trial

Immune checkpoint blockade (ICB) added to neoadjuvant chemotherapy (CTx) improves outcome for early stage TNBC patients, but it is largely unknown which patients truly benefit from ICB and for whom CTx can be de-escalated. Moreover, the addition of anti-CTLA4 to anti-PD1 has not been explored in early TNBC. In the first two cohorts of the adaptive phase II BELLINI trial we test the hypothesis that 4 weeks of neoadjuvant nivolumab (nivo) ± low dose ipilimumab (ipi, 1mg/kg) can induce immune responses in TNBC harboring TILs (TILs≥5%).

Precision Breast Cancer Medicine: Early Stage Triple Negative Breast Cancer-A Review of Molecular Characterisation, Therapeutic Targets and Future Trends.

Personalised approaches to the management of all solid tumours are increasing rapidly, along with wider accessibility for clinicians. Advances in tumour characterisation and targeted therapies have placed triple-negative breast cancers (TNBC) at the forefront of this approach. TNBC is a highly heterogeneous disease with various histopathological features and is driven by distinct molecular alterations. The ability to tailor individualised and effective treatments for each patient is of particular importance in this group due to the high risk of distant recurrence and death. The mainstay of treatment across all subtypes of TNBC has historically been cytotoxic chemotherapy, which is often associated with off-target tissue toxicity and drug resistance. Neoadjuvant chemotherapy is commonly used as it allows close monitoring of early treatment response and provides valuable prognostic information. Patients who achieve a complete pathological response after neoadjuvant chemotherapy are known to have significantly improved long-term outcomes. Conversely, poor responders face a higher risk of relapse and death. The identification of those subgroups that are more likely to benefit from breakthroughs in the personalised approach is a challenge of the current era where several targeted therapies are available. This review presents an overview of contemporary practice, and promising future trends in the management of early TNBC. Platinum chemotherapy, DNA damage response (DDR) inhibitors, immune checkpoint inhibitors, inhibitors of the PI3K-AKT-mTOR, and androgen receptor (AR) pathways are some of the increasingly studied therapies which will be reviewed. We will also discuss the growing evidence for less-developed agents and predictive biomarkers that are likely to contribute to the forthcoming advances in this field. Finally, we will propose a framework for the personalised management of TNBC based upon the integration of clinico-pathological and molecular features to ensure that long-term outcomes are optimised.

Abstract 2525: Understanding triple-negative breast cancer immune microenvironment by disease stages, obesity, and race

Abstract Background: Triple-negative breast cancer (TNBC) is a molecularly heterogeneous group of clinically aggressive malignancies. There are well-recognized health disparities in TNBC outcomes, and the risk of TNBC is higher among African-Americans (AA). It is unclear whether immunological features of the tumor microenvironment (TME) associated with disease stage, socioeconomic factors, or comorbidities such as obesity may affect tumor immunity. The incidence of TNBC and obesity in Louisiana is among the highest in the nation, and we have documented disparities in incidence linked to race and disparities in mortality linked to social determinants of health. Recent studies described immunologic characteristics of the TNBC TME. However, the possible association of immunogenomic portraits of TNBCs with race, comorbidities or socioeconomic factors remains understudied. Methods: We studied the expression of immunity-associated genes in clinically annotated TNBCs from Louisiana AA and European-American (EA) patients with or without obesity. Primary invasive breast cancer cases with confirmed TNBC diagnosis were identified by the Louisiana Tumor Registry (LTR). Sections of FFPE tissue containing ≥ 50% tumor were identified and processed for RNA-Sequencing [(n = 256; White women:125 (Lean: 50 and Obese:75) and Black women:131 (Lean:28 and Obese: 103)] at Translational Genomic Core, LSUHSC. Categorical outcomes were compared via Chi-squared tests, and survival was compared via log-rank tests. Spearman correlation analysis was used to determine associations between CIBERSORT cell populations and stage of disease at diagnosis. Results: We found that race was associated with the stage of TNBC, and AA patients were more often diagnosed with a later stage of TNBC (p=0.0447). However, race was not associated with survival (p=0.4673). Obesity was not associated with stage at diagnosis (p=0.7256). Stage at diagnosis was the strongest determinant of survival (p<0.0001). We utilized CIBERSORT analysis to identify and quantify immune cell populations within the TME. Later stage at diagnosis was associated with increased T follicular helper cells (p=0.0038), M1 macrophages (p= 0.0032), and activated mast cells (p=0.0487). Conversely, later stage of disease was associated with decreased resting mast cells (p=0.0004) and monocytes (p=0.0455). Immunosuppressive Treg cells were positively associated with stage at diagnosis in AA patients (p=0.0273) but not in EA patients (p=0.9141). Conclusions: Stage at diagnosis was the strongest determinant of survival and was associated with significant differences in TME immune cell populations. Stage, race and obesity were associated with the presence of immunosuppressive Treg cells. If confirmed, these findings may help understand the variability in immunotherapy responses in TNBC. Citation Format: Fokhrul Hossain, Denise Danos, Jovanny Zabaleta, Jiande Wu, Mary Anne Lynch, Luis Del Valle, Xiao-Cheng Wu, Augusto Ochoa, Chindo Hicks, Lucio Miele. Understanding triple-negative breast cancer immune microenvironment by disease stages, obesity, and race [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2525.

Abstract 1845: Exploring the mode of action of a highly efficacious ruthenium-based chemotherapeutic agent in triple negative breast cancer

Abstract Purpose: Triple negative breast cancer (TNBC) is an aggressive subtype of breast cancer that is defined by the absence of expression of progesterone receptor, estrogen receptor, and human epidermal growth factor receptor 2. TNBC has a higher incidence in younger women and those of African descent. Due to the inability to target a receptor, treatment is mostly limited to anthracycline and taxane-based nonspecific chemotherapy. Within the past two years more therapies have become available for later stage TNBC, such as antibody-drug conjugate sacituzumab govitecan-hziy. A potential water-soluble ruthenium-based chemotherapeutic agent was developed in our lab, showing high cytotoxicity against different cancer types in a National Cancer Institute 60-cell line panel. A preliminary in vivo study of this complex showed a pronounced 56% reduction of tumor growth with a TNBC MDA-MB-231 cell line xenograft mouse model, with little system toxicity and preferential accumulation of the complex in tumor tissue. These studies prompted us to further evaluate it in TNBC cell lines MDA-MB-231 and HCC-1806, derived from Caucasian and African ancestry patients respectively. This investigation revealed significant anti-angiogenic, anti-invasive, and anti-migratory properties for the complex, along with subcellular accumulation in the mitochondria and an apoptotic mechanism of cell death in both cell lines. Preliminary proteomic analysis was completed to understand the molecular pathway involved, which was determined to be P53-independent. Macrophage colony stimulating factor (M-CSF) showed an inhibition of protein expression, implicating the ruthenium complex as a potential inhibitor of phosphoinositide 3-kinases/protein kinase B (PI3K/Akt) pathway which acts downstream of M-CSF, and is involved with enhanced cancerous proliferation. In light of these findings, we report here on in vitro studies focused on further investigating the involvement of the PI3K/Akt molecular pathway and mechanism of action of this ruthenium complex. Experimental Design: Western blot studies directed toward key markers in the PI3K/Akt pathway will be assessed, which include Akt, c-Raf, PI3K, PTEN, and PDK1. Furthermore, mitochondrial involvement was determined through reactive oxygen species (ROS) generation and changes to mitochondrial membrane potential (MMP). Results: A significant increase of ROS generation was seen with exposure to the compound, along with slight MMP depolarization. Western blot analysis may further implicate an inhibition of the PI3K/Akt pathway. Conclusions: Our results show that the mechanistic action of the tested ruthenium complex has mitochondrial involvement, with inhibitory effects in the PI3K/Akt pathway. The very significant anti-cancer properties outlined in the preclinical evaluation of this complex will be further investigated in PDX mice models. Citation Format: Nazia Nayeem, Karen Hubbard, Maria Contel. Exploring the mode of action of a highly efficacious ruthenium-based chemotherapeutic agent in triple negative breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1845.

Phase I trial of an alpha-lactalbumin vaccine in patients with moderate- to high-risk operable triple-negative breast cancer (TNBC).

TPS1125 Background: Triple-negative breast cancer (TNBC) is the subtype of breast cancer with the worst prognosis and is the subtype most often associated with germline mutations of BRCA1 and certain other genes. Alpha-lactalbumin (aLA) is a milk protein that is expressed in lactating breasts but not at other times or in other normal tissues. Expression of aLA is found in approximately 70% of TNBC (Cancers PMID: 27322324) so is an attractive immunologic target for TNBC based on the “retired protein hypothesis” (Semin Immunol PMID: 31926646). Pre-clinical studies have shown that vaccination with aLA provides treatment of established and, more potently, protection from development of autochthonous tumors in transgenic murine models of breast cancer and against 4T1 transplantable breast cancer in BALB/c mice (Nat Med PMID: 20512124). We are conducting a Phase I trial in patients with early stage TNBC to demonstrate the safety of this approach and to document the ability to produce a meaningful immunologic response to aLA. Methods: Patients with ER-negative, PR-negative, HER2-negative breast cancer of pathologic stage I-III or who had residual disease after standard pre-operative systemic therapy are being entered into a Phase I trial of alpha-lactalbumin with a GMP-grade zymosan adjuvant in Montanide ISA 51 VG vehicle. Participants must be within 3 years of initiation of treatment and have no evidence of recurrence. Patients receive a total of 3 vaccinations administered once every 2 weeks with doses escalated using a 3+3 trial design. Toxic events of Common Terminology Criteria for Adverse Events (CTCAE) grade 2 or greater are considered dose-limiting. Dose levels being tested are alpha-lactalbumin/zymosan 0.01 mg/0.01 mg, 0.1 mg/0.1 mg, and 1 mg/1 mg. Patients are being monitored for toxicity until 84 days after the first vaccination or resolution of toxicity, whichever is later. Blood is being drawn prior to therapy and 14, 28, and 56 days after the first vaccination to assess cellular response using enzyme-linked immunosorbent spot (ELISpot) assays of interferon-gamma and interleukin-17 production in response to aLA. Humoral response to aLA vaccination is being assessed by enzyme-linked immunosorbent assay (ELISA). After identification of the Maximum Tolerated Dose we will expand the dose levels associated with effective tumor immunity and enroll a cohort of patients without cancer planning to undergo prophylactic bilateral mastectomy. Funding Source: Department of Defense (W81XWH-17-1-0592 and W81XWH-17-1-0593). Clinical trial information: NCT04674306.

Phase I/II trial of RVU120 (SEL120), a CDK8/CDK19 inhibitor in patients with relapsed/refractory metastatic or advanced solid tumors.

e15091 Background: CDK 8 /CDK19 are kinases involved in transcriptional control of embryonic development and cellular homeostasis via the mediator complex. They are also described to maintain tumor dedifferentiation and stem cell properties. A variety of cancer cells hijack the mediator complex and targeting cancer-specific gene transcription via CDK8/19 inhibition has potential for treatment of solid tumors. RVU120 (SEL120) is a selective CDK8/19 inhibitor with preclinical efficacy in hematologic malignancies and a variety of solid tumor types (Rzymski et al. 2017). RVU120 showed strong anticancer activity in preclinical triple-negative breast cancer (TNBC) models, especially in the mesenchymal stem-like (MSL) molecular subtype (Rzymski et al SABCS 2021). Methods: A Phase I/II clinical trial of RVU120 in solid tumors is currently ongoing (NCT05052255). Patients with metastatic or advanced solid tumors without available treatments receive increasing doses of RVU120 as a single oral dose every other day (QOD) for a total of 7 doses on Days 1, 3, 5, 7, 9, 11 and 13, in a 3-week treatment cycle. Primary objectives of the study are safety / tolerability of RVU120 as single agent and determination of the recommended Phase II dose (RP2D) via a 3+3 dose escalation design. Secondary objectives include objective response rate (ORR) (RECIST criteria v1.1) and PK of RVU120. Results: As of 11FEB 2022, 5 pts have been enrolled into the trial: 3 into cohort 1, 75 mg dose, 2 into cohort 2, 100 mg. None of the pts experienced a DLT, SAEs or > Grade 3 AE. Treatment-related AEs were all G1 except for G2 diarrhea and weakness. Cohort 1 patients had at least 1 post-baseline tumor assessment. A 62 YO patient, stage IV esophago-gastric junction carcinoma, metastases to the liver, retroperitoneum, adrenal gland and portocaval lymph nodes, progressing after 4 lines of previous therapy, achieved a SD with a +4% change of target lesion size and progressed in cycle 6. A 65 YO patient, stage IV adenoid cystic carcinoma of the trachea, metastases to the lung and refractory to antiandrogens and radiotherapy, achieved a SD with -4% change of target lesion size after 3 cycles and is currently ongoing in cycle 5. A 43 YO pt stage IV thymic carcinoma, metastases to the lung, mediastinum, pleura and lymph nodes, progressing under cisplatin/etoposide, stopped study drug at the end of cycle 3 for PD in non-target lesions, target lesions increased by 11%. Cohort 2 patients, a 65 YO pt with pancreatic cancer stage IV, metastases to liver and lung, and a 55 YO pt with TNBC stage IV, metastases to the lung, will be evaluated end of cycle 3. Conclusions: In the first dose escalation level with single agent RVU120, no DLTs or ≥G3 AEs were observed in patients with previously progressive solid tumors. Initial assessments in 3 pts demonstrated stable disease in 2 patients. Collection of further data at higher doses is ongoing with 2 patients enrolled at 100 mg. Clinical trial information: NCT05052255.

Are we overtreating stage I triple negative breast cancer in Ontario? A population-based study using the ICES database.

e12511 Background: Triple-negative breast cancer (TNBC) has been associated with poorer long-term outcomes compared to other breast cancer subtypes. Due to the lack of targeted therapies, the use of adjuvant chemotherapy is the mainstay of treatment, and its efficacy has demonstrated to be correlated with tumor size. Currently, different national guidelines exist regarding chemotherapy in early stage I TNBC. This study aims to examine the outcomes of the use of adjuvant chemotherapy in stage I TNBC stratified by tumor size and treated in Ontario, using the ICES database. Methods: Records of stage I TNBC patients diagnosed in 2012 to 2014 were collected from the ICES database and analysed. Kaplan-Meier curves and log-rank tests were used to compared differences in overall survival (OS) between groups. Stage I TNBC cancer patients were analyzed by tumor size: T1a (< 0.5 cm), T1b (> 0.5 cm and < 1.0 cm) and T1c (>1.0 cm and < 2.0 cm). A Cox proportional hazard model was used to determine significance of variables. Results: Of the 610 stage I TNBC patients, 183 had tumor sizes ≤ 1cm, representing stages T1aN0M0 and T1bN0M0, and 427 had tumor sizes > 1cm to 2cm, representing stage T1cN0M0. Patients with tumor sizes ≤ 1cm who received adjuvant chemotherapy did not have a significant difference in OS compared to those who did not receive adjuvant chemotherapy (p = 0.41, hazard ratio (HR) = 0.40, 95% confidence interval (CI) 0.021-2.5). However, patients with tumor sizes > 1cm to 2cm who received adjuvant chemotherapy demonstrated a significantly better OS compared to those without (p = 0.023, HR = 0.40, 95% CI 0.16-0.86). Conclusions: Patients with TNBC stage T1cN0M0 should receive adjuvant chemotherapy for better OS. For stages T1aN0M0 and T1bN0M0, patients may be overtreated and avoidance of adjuvant chemotherapy can be considered at this time. Prospective studies should investigate the efficacy of adjuvant chemotherapy in TNBC patients with stage T1aN0M0 and T1bN0M0.

A positive feedback loop: RAD18-YAP-TGF-\u03b2 between triple-negative breast cancer and macrophages regulates cancer stemness and progression

As a key regulator of the DNA translesion synthesis (TLS) pathway, RAD18 is error-prone and contributes to the accumulation of DNA mutations. Our previous study showed that it plays an essential role in the progression of multiple tumors. However, the mechanism through which RAD18 influences triple-negative breast cancer (TNBC), especially the interaction between tumor cells and the tumor microenvironment, remains elusive. In this study, we showed that RAD18 expression is markedly higher in patients with high T stage TNBC and inversely correlated with prognosis. High expression of RAD18 facilitated a highly stem-cell phenotype through the Hippo/YAP pathway, which supports the proliferation of TNBC. In addition, the cytokine byproduct TGF-β activates macrophages to have an M2-like tumor-associated macrophage (TAM) phenotype. Reciprocally, TGF-β from TAMs activated RAD18 in TNBC to enhance tumor stemness, forming a positive feedback loop. Inhibition of YAP or TGF-β breaks this loop and suppresses cancer stemness and proliferation In nude mice, RAD18 promoted subcutaneous transplanted tumor growth and M2-type TAM recruitment. Collectively, the RAD18-YAP-TGF-β loop is essential for the promotion of the stemness phenotype by TNBC and could be a potential therapeutic target for TNBC.