Radiomics Assessment of the Tumor Immune Microenvironment to Predict Outcomes in Breast Cancer

BackgroundThe immune microenvironment of tumors provides information on prognosis and prediction. A prior validation of the immunoscore for breast cancer (ISBC) was made on the basis of a systematic assessment of immune landscapes extrapolated from a large number of neoplastic transcripts. Our goal was to develop a non-invasive radiomics-based ISBC predictive factor.MethodsImmunocell fractions of 22 different categories were evaluated using CIBERSORT on the basis of a large, open breast cancer cohort derived from comprehensive information on gene expression. The ISBC was constructed using the LASSO Cox regression model derived from the Immunocell type scores, with 479 quantified features in the intratumoral and peritumoral regions as observed from DCE-MRI. A radiomics signature [radiomics ImmunoScore (RIS)] was developed for the prediction of ISBC using a random forest machine-learning algorithm, and we further evaluated its relationship with prognosis.ResultsAn ISBC consisting of seven different immune cells was established through the use of a LASSO model. Multivariate analyses showed that the ISBC was an independent risk factor in prognosis (HR=2.42, with a 95% CI of 1.49–3.93; P<0.01). A radiomic signature of 21 features of the ISBC was then exploited and validated (the areas under the curve [AUC] were 0.899 and 0.815). We uncovered statistical associations between the RIS signature with recurrence-free and overall survival rates (both P<0.05).ConclusionsThe RIS is a valuable instrument with which to assess the immunoscore, and offers important implications for the prognosis of breast cancer.

Variable Expression of the Disialoganglioside GD2 in Breast Cancer Molecular Subtypes

The disialoganglioside GD2 is a tumor-associated antigen that may allow for the application of targeted immunotherapies (anti-GD2 antibodies, GD2 CAR T cells) in patients with neuroblastoma and other solid tumors. We retrospectively investigated GD2 expression in a breast cancer cohort, using immunohistochemistry (IHC) and immunofluorescence (IF) on tissue microarrays (TMAs), and its impact on survival. GD2 expression on IHC (n = 568) and IF (n = 503) was investigated in relation to subtypes and patient outcome. Overall, 50.2% of the 568 IHC-assessed samples and 69.8% of the 503 IF-assessed samples were GD2-positive. The highest proportion of GD2-positive tumors was observed in luminal tumors. Significantly fewer GD2-positive cases were detected in triple-negative breast cancer (TNBC) compared with other subtypes. The proportion of GD2-expressing tumors were significantly lower in HER2-positive breast cancer in comparison with luminal tumors on IF staining (but not IHC). GD2 expression of IHC or IF was not significantly associated with disease-free or overall survival, in either the overall cohort or in individual subtypes. However, GD2 expression can be seen in more than 50% of breast cancer cases, with the highest frequency in hormone receptor-positive tumors. With this high expression frequency, patients with GD2-positive advanced breast cancer of all subtypes may benefit from GD2-targeting immunotherapies, which are currently subject to clinical testing.

P06.04 Transcriptome-wide network analysis predicts the role of lactate dehydrogenase C in breast cancer cell survival and immune dysfunction

BackgroundCancer testis antigens (CTAs) are lucrative anti-cancer targets given their restricted expression patterns and known roles as mediators of cancer hallmarks, including cancer metabolism, proliferation, survival, and cell motility. Lactate dehydrogenase C (LDHC) is a CTA with upregulated expression in poor prognosis subtypes of breast cancer, however its tumorigenic role is less understood. We recently reported that silencing LDHC reduces breast cancer cell survival through a dysregulated DNA damage response, thus highlighting its potential as an anti-cancer target with limited off-target effects. This study aimed to explore the changes in the transcriptome of breast cancer cells and immune-related mediators upon in vitro LDHC targeting.Materials and MethodsWe silenced LDHC expression in breast cancer cell lines and investigated the downstream effects on the tumor cell transcriptome. Differentially expressed genes were subjected to regulatory network analyses. We further assessed the secretory profile of cytokines and immune checkpoint expression in LDHC-silenced cells and used the Tumor Immune Dysfunction and Exclusion (TIDE) algorithm to determine the effect of the interaction between LDHC expression and cytotoxic T lymphocyte (CTL) infiltration in the METABRIC breast cancer cohort.ResultsNetwork analysis to investigate the effects of silencing LDHC on the tumor cell transcriptome identified 47 up- and 55 down-regulated transcripts (2.0-fold change, adj p<0.05). Differentially expressed genes in the LDHC-silenced cells were particularly enriched in canonical pathways regulating cell cycle checkpoint control, BRCA1-mediated DNA damage response and NF-kb signaling in response to infection. Upstream regulator analyses revealed the altered expression profile was associated with mTOR (p=1.27e-5, z=2.242) and CASP3 (p=3.2e-4, z=2.250) pathways, which in the presence of LDHC are predicted to activate TP53, Myc, NF-KB complex, STAT1/3, PRKC, CDK2, FOXO3 and HIF-1a while inhibiting SMAD3, PTEN, ATM, IL18 and BCL2. Consequentially, the observed network-wide changes on LDHC silencing are predicted to negatively influence cellular growth and proliferation, cell migration and cell infiltration. The LDHC-associated network indicated a higher-level regulation by miR378a-3p (p=1.4e-7, z=-3.117), affecting the downstream mechanistic in LDHC-expressing cells. Interestingly, the miR378a causal network also indicated inhibition of the immune response in LDHC-positive cells. TIDE analysis indicated that high expression of LDHC in the METABRIC Her2 breast cancer cohort (TIDE score=1.97, p=0.049), and to a lesser extent in triple negative breast cancer (TIDE score=0.466, p=0.642), decreases the beneficial effect between CTLs and overall survival observed in LDHC Low tumors. Concurrently, LDHC-silenced cells displayed a pro-inflammatory gene expression and cytokine profile and down-regulated the expression of PD-L1 and Gal-9 immune checkpoints.ConclusionsOur findings provide an indication of potential CTL dysfunction in breast tumors with high LDHC expression and suggests that therapeutic targeting of LDHC may inhibit tumor growth while releasing the anti-tumor immune response in breast cancer.Disclosure InformationA. Naik: None. J. Decock: None.

Radiogenomics Analysis Reveals Tumor Heterogeneity of Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is a subset of breast cancer with adverse prognosis and significant tumor heterogeneity. Here, we used MRI images from a breast cancer cohort consisting of 860 patients to construct a radiomic signature that could identify TNBC with an AUC of 0.92 (95% CI: 0.887 to 0.953) and validated in another cohort. Moreover, we developed radiomic signatures to distinguish TNBC subtypes with moderate efficacy. Furthermore, we identified peritumoral dependence nonuniformity of the gray level dependence matrix, which captures the intratumor heterogeneity in the tumor boundary, as the most significant prognostic factor (P = 0.04 for recurrence-free survival and P = 0.02 for overall survival). The integration of transcriptomic and metabolomic data indicated that high peritumor heterogeneity was related to immune suppression and enhanced metabolism. Our findings suggest that radiomics data can serve as a noninvasive predictor for molecular subtyping and clinical outcome in patients with TNBC.

SEC61G promotes breast cancer development and metastasis via modulating glycolysis and is transcriptionally regulated by E2F1

Breast cancer is the most common cancer in women and its incidence rates are rapidly increasing in China. Understanding the molecular mechanisms of breast cancer tumorigenesis enables the development of novel therapeutic strategies. SEC61G is a subunit of the endoplasmic reticulum translocon that plays critical roles in various tumors. We aimed to investigate the expression and function of SEC61G in breast cancer. By analyzing The Cancer Genome Atlas breast cancer cohort, we found that SEC61G was highly expressed in breast cancer and predicted poor prognosis of breast cancer patients. Overexpression of SEC61G and its prognostic role was also confirmed in the Nanjing Medical University (NMU) breast cancer cohort. Functionally, we demonstrated that knockdown of SEC61G suppressed breast cancer cell proliferation, migration, invasion, and promoted breast cancer cell apoptosis in vitro. Xenograft breast tumor model revealed that knockdown of SEC61G inhibited breast tumor development in vivo. Furthermore, we demonstrated that SEC61G positively regulated glycolysis in breast cancer cells. Mechanistically, we showed that transcription factor E2F1 directly bound to the promoter of SEC61G and regulated its expression in breast cancer cells. SEC61G overexpression antagonized the effect of E2F1 knockdown in regulating breast cancer cell proliferation, invasion, and apoptosis. Finally, we demonstrated that the E2F1/SEC61G axis regulated glycolysis and chemo-sensitivity of Herceptin in breast cancer cells. Taken together, these results of in vitro and in vivo studies demonstrate that SEC61G promotes breast cancer development and metastasis via modulating glycolysis and is transcriptionally regulated by E2F1, which might be utilized as a promising therapeutic target of breast cancer treatment.

Assessment of vitamin D deficiency and COVID-19 diagnosis in patients with breast or prostate cancer using electronic medical records.

6589 Background: While patients with cancer are known to be at increased risk of infection in part due to the immunocompromising nature of cancer treatments, recent data indicate a particularly high risk for COVID-19 infection and poor outcomes (Wang et al., 2020). A recent study (Meltzer et al., 2020) demonstrated Vitamin D deficiency may increase risk of COVID-19 infection, and a small randomized controlled trial in Spain reported significant improvement in mortality among hospitalized patients treated with calcifediol. Vitamin D deficiency has been reported in two leading causes of cancer deaths: breast and prostate. In this study, we performed a retrospective cohort analysis on nationally representative electronic medical records (EMR) to assess whether Vitamin D deficiency affects risk of COVID-19 among these patients. Methods: Patients with breast (female) or prostate (male) cancer were identified between 3/1/2018 and 3/1/2020 from EMR data provided pro-bono by the COVID-19 Research Database ( covid19researchdatabase.org ). Patients with an ICD-10 code for Vitamin D deficiency or < 20ng/mL 20(OH)D laboratory result within 12 months prior to 3/1/2020 were classified as Vitamin D deficient. COVID-19 diagnosis was defined using ICD-10 codes and laboratory results for COVID-19 at any time after 3/1/2020. Logistic regressions, adjusting for baseline demographic and clinical characteristics, were conducted to estimate the effect of Vitamin D deficiency on COVID-19 incidence in each cancer cohort. Results: A total of 16,287 breast cancer and 14,919 prostate cancer patients were included in the study. The average age was 68.9 years in the breast cancer cohort and 73.6 years in the prostate cancer cohort. The breast cancer cohort consisted of 85% Whites, 13% Black or African Americans, and less than 5% of other races. A similar race distribution was observed in the prostate cancer cohort. Unadjusted analysis showed the risk of COVID-19 was higher among Vitamin D deficient patients compared to non-deficient patients in both cohorts (breast: OR = 1.60 [95% C.I.: 1.15, 2.20]; prostate: OR = 1.59 [95% C.I.: 1.08, 2.33]). Similar findings were observed when assessed in subgroups of patients with newly diagnosed cancer in the dataset, as well as after adjusting for baseline characteristics. Conclusions: Our study suggests breast and prostate cancer patients may have an elevated risk of COVID-19 infection if Vitamin D deficient. These results support findings by Meltzer et al., 2020 demonstrating a relationship between Vitamin D deficiency and COVID-19 infection. While a randomized clinical trial is warranted to confirm the role for Vitamin D supplementation in preventing COVID-19, our study underscores the importance of monitoring Vitamin D levels across and within cancer populations, particularly in the midst of the global COVID-19 pandemic.