Breast Cancer Cohort Research Articles

The expression patterns of different cell types and their interactions in the tumor microenvironment are predictive of breast cancer patient response to neoadjuvant chemotherapy.

The tumor microenvironment (TME) is a complex ecosystem of diverse cell types whose interactions govern tumor growth and clinical outcome. While the TME's impact on immunotherapy has been extensively studied, its role in chemotherapy response remains less explored. To address this, we developed DECODEM (DEcoupling Cell-type-specific Outcomes using DEconvolution and Machine learning), a generic computational framework leveraging cellular deconvolution of bulk transcriptomics to associate the gene expression of individual cell types in the TME with clinical response. Employing DECODEM to analyze the gene expression of breast cancer (BC) patients treated with neoadjuvant chemotherapy, we find that the gene expression of specific immune cells (myeloid, plasmablasts, B-cells) and stromal cells (endothelial, normal epithelial, CAFs) are highly predictive of chemotherapy response, going beyond that of the malignant cells. These findings are further tested and validated in a single-cell cohort of triple negative breast cancer. To investigate the possible role of immune cell-cell interactions (CCIs) in mediating chemotherapy response, we extended DECODEM to DECODEMi to identify such CCIs, validated in single-cell data. Our findings highlight the importance of active pre-treatment immune infiltration for chemotherapy success. The tools developed here are made publicly available and are applicable for studying the role of the TME in mediating response from readily available bulk tumor expression in a wide range of cancer treatments and indications.

Deep learning for automated scoring of immunohistochemically stained tumour tissue sections – Validation across tumour types based on patient outcomes

We aimed to develop deep learning (DL) models to detect protein expression in immunohistochemically (IHC) stained tissue-sections, and to compare their accuracy and performance with manually scored clinically relevant proteins in common cancer types.Five cancer patient cohorts (colon, two prostate, breast, and endometrial) were included. We developed separate DL models for scoring IHC-stained tissue-sections with nuclear, cytoplasmic, and membranous staining patterns. For training, we used images with annotations of cells with positive and negative staining from the colon cohort stained for Ki-67 and PMS2 (nuclear model), the prostate cohort 1 stained for PTEN (cytoplasmic model) and β-catenin (membranous model). The nuclear DL model was validated for MSH6 in the colon, MSH6 and PMS2 in the endometrium, Ki-67 and CyclinB1 in prostate, and oestrogen and progesterone receptors in the breast cancer cohorts. The cytoplasmic DL model was validated for PTEN and Mapre2, and the membranous DL model for CD44 and Flotillin1, all in prostate cohorts. When comparing the results of manual and DL scores in the validation sets, using manual scores as the ground truth, we observed an average correct classification rate of 91.5 % (76.9–98.5 %) for the nuclear model, 85.6 % (73.3–96.6 %) for the cytoplasmic model, and 78.4 % (75.5–84.3 %) for the membranous model. In survival analyses, manual and DL scores showed similar prognostic impact, with similar hazard ratios and p-values for all DL models. Our findings demonstrate that DL models offer a promising alternative to manual IHC scoring, providing efficiency and reproducibility across various data sources and markers.

Enfortumab vedotin (EV) in triple-negative breast cancer (TNBC) and HR+/HER2- breast cancer (BC) cohorts of EV-202.

1005 Background: EV, a Nectin-4–directed antibody–drug conjugate, is approved for use in urothelial cancer. Nectin-4 is expressed in several solid tumors, including BC. EV monotherapy was evaluated in TNBC and HR+/HER2- BC in EV-202 (NCT04225117). Methods: In this open-label, multicohort, phase 2 trial, eligible adults had locally advanced or metastatic (la/m) solid tumors, measurable disease, and ECOG PS 0–1. In BC cohorts, patients (pts) had prior taxanes or anthracyclines, ≥1 standard-of-care cytotoxic regimen and ≤2 lines (L) of cytotoxic therapy for la/mBC, and prior PD-1/L1 inhibitor (TNBC) or endocrine treatment (tx) with a CDK4/6 inhibitor (HR+/HER2- BC). Nectin-4 expression was not required but was assessed retrospectively. Pts received EV 1.25 mg/kg intravenously days 1, 8, and 15 of each 28-d cycle until discontinuation criteria (eg, disease progression, unacceptable toxicity) were met. Primary endpoint was confirmed objective response rate (ORR); ≥10 (TNBC) or ≥12 (HR+/HER2- BC) responders out of 40 evaluable pts were needed to claim promising antitumor activity. Secondary endpoints were duration of response (DOR), disease control rate (DCR), progression-free survival (PFS), overall survival (OS), and safety/tolerability. Antitumor activity was investigator-assessed per RECIST v1.1. Results: In the TNBC cohort, 42 female pts received EV as of Mar 3, 2023 (median follow-up, 11.8 mo). Median age was 53 y, 64% had ≥2L systemic tx for metastatic BC, and 33% had prior sacituzumab govitecan. ORR was 19.0%. Grade ≥3 tx-related adverse events (TRAEs) in >1 pt were decreased neutrophil count (n=3, 7%), decreased white blood cell count (n=2, 5%), and increased aspartate aminotransferase (n=2, 5%). Selected TRAEs of special interest were skin reactions (n=25, 60%), peripheral neuropathy (n=11, 26%), and hyperglycemia (n=2, 5%). In the HR+/HER2- BC cohort (median age, 57.0 y), 45 female pts received EV as of Dec 3, 2022 (median follow-up, 11.2 mo). Most (73%) had ≥3L systemic tx for metastatic BC. ORR was 15.6%. Grade ≥3 TRAEs in >1 pt were maculopapular rash (n=7, 16%), pruritus and increased aspartate aminotransferase (both n=3, 7%), and abdominal pain and erythema (both n=2, 4%). Selected TRAEs of special interest were skin reactions (n=28, 62%), peripheral neuropathy (n=12, 27%), and hyperglycemia (n=5, 11%). Additional efficacy data for both cohorts are in the table. Conclusions: EV showed antitumor activity in heavily pretreated TNBC. Safety in both cohorts was manageable and consistent with previous reports. Clinical trial information: NCT04225117 . [Table: see text]

Time-to-diagnosis and peri-diagnostic healthcare utilization between screen- and non-screen detected cancers: Evidence from SEER-Medicare.

11135 Background: Cancer screening programs can improve outcomes and may reduce treatment cost and utilization by shifting cancers to earlier, more curable stages at diagnosis (Dx). Few studies have evaluated the impact of screening on outcomes prior to diagnosis. Such information is needed to better understand the potential impact of newer blood-based multicancer early detection technologies. Methods: We conducted a retrospective cohort study using SEER cancer registry data linked with Medicare claims. Patients with a breast cancer (BC) or colorectal cancer (CRC) Dx between 2010-2019 were included if they were 65-74 years old at Dx, continuously enrolled in Medicare Parts A&B, had a Charlson Comorbidity Index of ≤2, and no cancer for ≥12 months prior to Dx. Those enrolled in an HMO or with high genetic risk for BC (in BC cohort) were excluded. Patients were assigned to screening groups prior to Dx; screening was defined as ≥1 screening procedure in the 6 months prior to Dx using CPT/HCPCS codes. Screening included FIT/FOBT, sigmoidoscopy, colonoscopy, CT colonography, mt-sDNA (CRC), and mammography (BC). Screened and not screened groups were compared for statistical significance using chi-squared for categorical variables, Wilcoxon rank-sum test for continuous variables. Results: Screening procedures were more prevalent in the BC cohort (68%) than the CRC cohort (44%) (table). Both screened subgroups (vs non-screened subgroups) had significantly lower proportions of patients diagnosed at stage 4 (2% vs 10% BC, 16% vs 27% CRC) and shorter times from first screening or imaging procedure to confirmed diagnosis (BC: 33 vs 227 days, CRC: 14 vs 29 days). Screened patients in both cancer cohorts had a similar number of average procedures prior to treatment initiation as non-screened (BC: 4.8 vs 4.2, CRC: 3.3 vs 3.3 respectively, including screening procedures). Conclusions: Individuals diagnosed with BC and CRC through screening exhibit earlier stage diagnoses and shorter intervals to diagnosis. Novel screening technologies such as MCED tests can potentially improve peri-diagnostic outcomes in cancers lacking existing or widely adopted screening methods. [Table: see text]

Large cohort analysis of incidental CDH1 PVs among patients undergoing MGPT.

10618 Background: Hereditary diffuse gastric cancer (HDGC) is an autosomal dominant condition caused by a heterozygous pathogenic variant (PV) in CDH1.HDGC is associated with an increased risk for DGC (33-70%) and invasive lobular breast cancer (LBC) (~64%) [1]. The National Cancer Center Network (NCCN) and International Gastric Cancer Linkage Consortium (IGCLC) recommend consideration of CDH1 germline testing based on personal and family history of DGC and LBC. However, with the advent of next generation sequencing and the inclusion of CDH1 in multigene panels (MGP), several cohort studies have identified CDH1+ patients who do not meet criteria [2,3,4,5]. Our group previously analyzed a cohort of patients with a personal or family history of BC who had CDH1 testing through MGPT and did not observe a significant association between CDH1 PVs and suspicion for HDGC (p-value=0.2066) [6]. In this expanded study, we aim to evaluate a larger cohort of patients of all cancer histories to gain a more comprehensive picture of the prevalence of incidental CDH1 PV among patients undergoing MGPT. Methods: 14,891 individuals who underwent CDH1 testing within MGPT were seen at MD Anderson’s Clinical Cancer Genetics (CCG) program between August 2013 and January 2024. This cohort was obtained from a prospectively maintained patient database within MD Anderson’s CCG program. Individuals were stratified based on CDH1 germline status (PV vs. negative or variant of uncertain significance) and meeting modified criteria for HDGC. Results: Within our expanded cohort, 1,716 individuals (11.5%) met criteria for suspicion for HDGC, while 13,715 did not meet criteria. Of the 70 individuals who tested positive for CDH1 (0.47%), 39 (0.28%) met criteria while 31 (0.23%) did not. We observed a statistically significant relationship between meeting our modified criteria for suspicion for HDGC and testing positive for a pathogenic variant in CDH1 (p-value <0.0001). Conclusions: Among patients who underwent CDH1 testing within MGPT, we observed a correlationbetween having a CDH1PV and meeting criteria for suspicion for HDGC. This contrasts with prior findings from our breast cancer cohort, potentially due to the limited number of CDH1 positive patients (n=3). These results suggest that while perhaps not robustly capturing HDGC families within a sub-population of patients undergoing MGPT, overall, NCCN and IGCLC guidelines closely reflect the clinical picture of a significant number of HDGC families. Meanwhile, the presence of incidental CDH1 PVs in this cohort portrays the variable expressivity and incomplete penetrance among patients with HDGC, including the detection of occult signet ring cell carcinomas during endoscopies or total gastrectomies [7]. We seek to expand this analysis by comparing these findings to rates of incidental CDH1 PVs in a subset of patients who meet NCCN guidelines for CDH1 testing based on suspicion for hereditary breast cancer syndromes.

Efficacy and genomic analysis of HER2-mutant, metastatic triple-negative breast cancer treated with neratinib alone or in combination with trastuzumab in the phase 2 SUMMIT basket trial.

1094 Background: Genomic analyses of the SUMMIT metastatic breast cancer (mBC) cohorts suggested that resistance to neratinib (N) occurred primarily via acquisition of additional HER2alterations [Smyth et al. Cancer Discovery 2020]; this finding was independently confirmed in the MutHER clinical trial [Ma et al. Clin Cancer Res 2022]. Addition of trastuzumab (T) to N + fulvestrant (F) in HR+, HER2-negative, HER2-mutant mBC revealed increased efficacy compared to N+F [Jhaveri et al. Ann Oncol 2023]. Here, we report final data from SUMMIT evaluating whether the addition of T to N could improve outcomes in patients (pts) with HER2-mutant, triple-negative mBC (representing up to 3% of triple-negative mBCs) and performed next-generation sequencing (NGS) of serial biopsies to evaluate mechanisms of sensitivity and resistance. Methods: Pts with HER2-mutant triple-negative mBC received N (original SUMMIT cohort) or N+T (in the subsequent cohort): oral N 240 mg/d, i.v. T 8 mg/kg initially followed by 6 mg/kg q3w. Loperamide prophylaxis was mandatory during the first two cycles. Efficacy endpoints: confirmed objective response rate and clinical benefit rate (RECIST v1.1 or modified PERCIST); duration of response; progression-free survival. Retrospective central NGS was performed by MSK-IMPACT (tissue) or MSK-ACCESS (plasma). Results: 10 and 17 pts with triple-negative mBC were enrolled in the N and the N+T cohorts, respectively. Median no. of prior systemic regimens for metastatic disease was 2.5 (range 0–6) for the N and 2 (range 0–7) for the N+T cohort. Efficacy findings are summarized (Table). Diarrhea was the most commonly reported adverse event (N 80% any grade; 20% grade 3; N+T 100% any grade; 18% grade 3; no grade 4/5 or permanent discontinuations in either cohort). Correlation of efficacy to central NGS analysis is ongoing and will be reported. Conclusions: Treatment with either N and/or N+T yielded promising clinical efficacy and has been included in recent NCCN guidelines for HER2-mutant, triple-negative mBC. Molecular mechanisms of intrinsic or acquired sensitivity/resistance per genomic analysis will be reported. Clinical trial information: NCT01953926 . [Table: see text]

The characteristics and prognostic significance of histone H1 expression in breast cancer

Histone H1 (H.H1) is involved in chromatin organisation and gene regulation and is overexpressed in many malignant tumours, including breast cancer (BC). This study proposed and evaluated the prognostic role of H.H1 expression in BC. H.H1 mRNA expression was evaluated in publicly available BC dataset bc-GenExMiner database (n=4421). H.H1 protein expression was assessed immunohistochemically in a well-characterised early-stage BC cohort (n=1311), and associations with clinicopathological data and survival outcomes were evaluated. At the mRNA level, there was a significant association between high H.H1 mRNA and basal-like BC subtype and with poor outcome. The association with shorter survival was observed in the whole cohort and in the basal-like class. H.H1 protein expression was detected in both tumour cells and surrounding stroma. Total expression was detected in 72% of the cases, including 28% in tumour cell nuclei and 44% in the stroma. There was strong association between high tumour H.H1 expression and triple-negative BC (TNBC) subtype (p=0.007) and with shorter survival (p=0.019), independent of other variables including tumour size, histologic tumour grade, and lymph node status. H.H1 expression is associated with poor prognosis in BC. Given poor prognostic role of H.H1 in TNBC, it may represent a potential therapeutic target for patients with this aggressive disease.

Multiomic analysis in ovarian clear cell carcinoma to gain insight into biology and therapeutic opportunities.

e17540 Background: Ovarian clear cell carcinoma (OCCC) is a rare subtype with distinct histologic and molecular features. The prognosis of advanced/recurrent OCCC treated with standard of care surgery and platinum-based chemotherapy remains poor due to inherent chemoresistance. Therefore, there is an urgent need to identify novel biological insights and personalized treatment approaches to improve outcomes. Methods: Participants were referred to the SMMART Program at the OHSU Knight Cancer Institute. Archival or fresh tissue was obtained from metastatic sites and processed through a multiomics platform that included immunohistochemistry (Ki67, HER2, CD4, CD8, PD-L1), fluorescent in-situ hybridization, targeted next-generation sequencing panel (225 genes), whole transcriptomic sequencing, chromosomal microarray, and multiplexed analysis of 67 key cancer proteins and phosphoproteins on the Nanostring GeoMx Digital Spatial Profiler. Results: 5 participants were enrolled with an average age of 62 years (range 52-72). Therapeutically relevant findings included detectable HER2 expression by IHC (2+, N=2; 3+, N=2), HER2 amplification by FISH (N=2), and high HER2 and phospho-HER2 protein expression compared to a breast cancer cohort (phospho-HER2 supports active HER2 signaling in the tumor cells). Additional findings include TMB <10 muts/Mb (N=5), microsatellite stable (N=5), Ki67 40-60% (N=4), mild to moderate CD4 and/or CD8 infiltration (N=4), PD-L1 >1% (N=3), low homologous recombination deficiency score (N=4), chromosomal losses including ATM, SMAD4, RB1, and TP53, and single nucleotide variations in ARID1A (N=4). Two participants with HER2 expression were treated with off-label trastuzumab deruxtecan for 6 or 7 cycles yielding significant clinical benefit. Participant A (HER2 = 3+, FISH negative) had an exceptional response while Participant B (HER2 = 2+, FISH amplified) had stable disease. The toxicity profile was consistent with literature. Conclusions: Our OCCC cohort revealed elevated HER2 expression with or without genomic amplification in 4/5 cases. Two participants experienced clinical benefit when treated with trastuzumab deruxtecan, supporting further exploration of HER2 antibody drug conjugates in this aggressive disease. More study is needed to determine the frequency of HER2 overexpression and amplification in OCCC, the importance of HER2 on OCCC pathophysiology, and the therapeutic benefit of targeting HER2 in this population.

Associations of predictive biomarkers, MHC-I and MHC-II, with clinical and molecular features in a diverse breast cancer cohort.

517 Background: The addition of immunotherapy (IO) to chemotherapy in triple negative breast cancer (TNBC) has improved survival outcomes and recent studies have also shown improvements in pCR rates in early high-risk HR+/HER2- breast cancer. However, these improvements are not without toxicities and thus there is a critical need for biomarkers to select patients that are most likely to benefit from immunotherapy. MHC-I and tumor-specific MHC-II (tsMHC-II) expression are candidate biomarkers for predicting PD-(L)1 checkpoint inhibition benefit and have previously shown potential for predicting treatment response in multiple tumor types, including breast cancer. However, the existing data were generated from clinical trials with limited racial/ethnic diversity. Here we report associations between MHC-I and MHC-II expression and clinicopathological features in a large, racially and ethnically diverse breast cancer cohort. Methods: We performed multiplexed immunofluorescent tissue-based analysis of participants in the Carolina Breast Cancer Study (CBCS). Intrinsic subtype and P53 mutant-like status were identified using RNA-based multigene assays. To evaluate MHC-I we ranked all participants based on tumoral MHC-I intensity, with the top 33% categorized as "MHC-IHigh"; MHC-II+ expression on tumor cells was defined as ≥5% of tumor cells. Association between MHC-I/II and clinicopathological features by race was tested using Chi-square test or fisher-exact test and relative frequency difference (RFD) was calculated. Results: This study included 1630 participants (48% Black and 52% non-Black) with Stage I-III breast cancer. Black participants had a higher incidence of TNBC (25% vs. 12.5%, p=<0.001) and Basal-like (29% vs. 14%, p=<0.001) tumors. Basal-like and TP53 mutant tumors were more frequently observed among Black participants with HR+/HER2- tumors (11% vs. 5.5%, p=0.006 for Basal-like; 26% vs. 17%, p=0.003 for p53 mutant-like). While there was a similar distribution of tsMHC-II+ tumors between Black and non-Black participants, the relative frequency of tsMHC-II+ tumors was significantly more common in Black participants with HR+/HER2- breast cancer compared to non-Black participants (7.9% vs. 5%, p=0.04). Moreover, Black participants also were significantly more likely to have MHC-Ihigh tumors (38.9% vs. 28.4%, p=0.01), which, after IHC subtype stratification, was only significant among participants with HR+/HER2- breast cancer (28.2% vs. 22.3%, p=0.02). Conclusions: In this diverse breast cancer cohort, MHC-I and MHC-II expression, candidate predictive biomarkers of IO benefit, were more prevalent in tumors from Black women with HR+/HER2- breast cancer. These results underscore the importance of diverse and equitable clinical trial enrollment in future IO trials, especially in HR+/HER2- breast cancer.

LC3AB protein-based gene (PbG) signatures as an indicator of relapse even after achieving pathological complete response.

e12552 Background: The application of tissue-based quantitative protein and morphological profiling of breast cancer tissues combined with RNA sequencing provides a flexible and generally applicable and scalable method to develop Protein-based Gene (PbG) signatures with significant prognostic value. Methods: A racially and subtype diverse breast cancer cohort (N=555) with available subset of RNA-seq data was used to develop gene expression-based signatures by stratifying patients according to protein expression (IHC) based on survival information and tumor lymphocyte infiltration (TILs) using survival-derived cutoff values. The predictive value of these signatures was then compared with other popular biomarkers scoring systems such as ROR.score, and OncotypeDx (Gene 21). Here we describe the predictive value of these signatures is evaluated by logistic regression modeling of publicly available gene expression data (N=996) from patients receiving neoadjuvant chemotherapy (anthracycline +/- taxane) with a final validation in an independent cohort (N=443) receiving similar therapy. Results: A model of PbG-derived signature from Kaiso, LC3A/B IHC and quantitative TIL-measurements together with ROR score, MAPK, PTEN, Immune and Gene21 signatures show significant prediction of distant metastasis-free survival in all patients: (DMFS, AUC= 0.737, 95% CI: 0.665- 0.819); and in non-pCR patients DMSF (AUC= 0.71, 95% CI: 0.633-0.773). When examining the role of all those markers among the patients who achieved the pCR and had relapse, the LC3A/B PbG-derived score was found to be highly predictive of those patients who would not achieve pCR and ultimately have recurrent disease. Conclusions: PbG-based signatures utilizing on LC3A/B protein values offer a novel and clinically relevant predictive biomarker of response to therapy and relapse in breast cancer patients.

Novel HLA-Ilo/HLA-IIhi phenotype and immune evasion in triple-negative breast cancer.

1095 Background: Immune checkpoint inhibitors (ICIs) are a therapeutic option for patients with triple-negative breast cancer (TNBC), however resistance and non-response remain an unmet clinical need. Human leukocyte antigens (HLAs) play an important role in induction and regulation of host immune responses. Downregulation of HLA class I expression is one mechanism by which cancer cells evade the immune control. HLA typing and understanding the role of HLAs can provide valuable insight into optimizing immunotherapy efficacy in TNBC. In this study, we evaluate the association of HLA I/II phenotypes with biomarkers of tumor immune interaction and overall survival (OS) in a real-world breast cancer cohort. Methods: A targeted RNA-seq assay was performed on 142 breast cancer samples. HLA I and HLA II expressions were estimated as average expression of HLA-A, HLA-B, HLA-C and HLA-DP, HLA-DQ, HLA-DR genes, respectively, by a percentile rank values [0-100]. Cohen D index was used to estimate ratio of HLA-I and II in each specimen. We particularly focused on the HLA-Ilow(lo)/HLA-IIhigh(hi) ratio given a proposed mechanism of immune escape by tumor cells (low expression of HLA-I) in response to a highly immune infiltrated state where there is increased expression of HLA-II by the immune cells. We studied the co-expression of HLA-Ilo/HLA-IIhi with other checkpoint targets using Spearman correlation(rs). The impact of HLA phenotypes on OS were analyzed using Kaplan-Meier analysis and Chi-squared assessed associations. Results: The cohort consisted of 106 non-TNBC (ER+/HER2- or HER2+) and 36 TNBC tumors. Most samples originated from metastatic visceral sites (96, 68%) followed by primary breast (33, 23%), and lymph nodes (13, 9%). Among TNBC, HLA-Ilo/HLA-IIhi phenotype displayed a significantly higher co-expression of immune checkpoint targets such as PD-1, PD-L1, TIM3 and LAG-3 than HLA-Ihi/HLA-IIlo phenotype (p<0.001). However, this difference was not observed between HLA-Ilo/HLA-IIhi and HLA-Ihi/HLA-IIlo phenotypes in non-TNBC tumors. In TNBC, there was no significant difference in OS between HLA-Ilo/HLA-IIhi when compared to HLA-Ihi/HLA-IIlo (43 vs. 37 months, p=0.21). Similarly, in non-TNBC, there were no significant differences in OS between HLA-Ilo/HLA-IIhi when compared to HLA-Ihi/HLA-IIlo (107 vs. 66 months, p=0.5). Conclusions: Concurrent loss of HLA I with increased HLA II expression was associated with co-expression of immune checkpoint molecules indicative of immune escape mechanism but not survival outcomes in TNBC. This same effect was not seen in non-TNBC with a more immunologically silent environment. Characterization of HLA phenotypes by immune profiling provides insight into the complex interplay of tumor immune microenvironment and offers an opportunity for developing novel approaches to overcome the immune evasion with cancer vaccines and adoptive cell therapies in TNBC.

Predictors of Endocrine Resistance in a Cohort of Mexican Breast Cancer Patients.

This study aimed to determine the prevalence of endocrine resistance in a cohort of Hispanic Mexican breast cancer (BC) patients receiving care at Instituto Nacional de Cancerología (INCan). Additionally, the clinical-pathological factors associated with endocrine resistance were identified, and their impact on patient survival was explored. A retrospective analysis of 200 BC patients who attended INCan between 2012 and 2016 with estrogen receptor (ER) and progesterone receptor (PR) positive tumors was made. Endocrine resistance was defined according to the International Consensus Guidelines for Advance Breast Cancer 2 definition. Their clinicopathological characteristics were analyzed to determine the association with endocrine resistance presence. We used sensitivity analyses and multivariate-adjusted logistic regressions, Kaplan-Meier curves, and multivariate-adjusted Cox regressions. P-value < 0.05 was considered as statistically significant. Endocrine resistance was observed in 32.5% of patients included in this study. The distinction between hormone resistance and sensitivity was influenced by tumor size and node status. It had a mean diameter of 7.15 cm in endocrine resistance cases compared to 5.71 cm in non-endocrine, with N3 status present in 20% of endocrine resistance cases versus only 2.2% in non-endocrine (p-value < 0.001). The clinical stage exhibited a strong association with endocrine resistance (Risk Ratio [RR] 4.39, 95% confidence interval [95%CI] 1.50, 11.43). Furthermore, endocrine resistance significantly impacted mortality during the follow-up, with a Hazard Ratio [HR] of 23.7 (95%CI 5.20, 108.42) in multivariable-adjusted models. However, a complete pathological response reduced the endocrine resistance risk, as demonstrated by a Risk Ratio (RR) of 0.15 (95% CI 0.03, 0.75). Advanced clinical stage at diagnosis predicted endocrine resistance in Hispanic Mexican BC patients. Complete pathologic response in locally advanced disease patients was also a key predictor of endocrine resistance. These results indicated that endocrine resistance was a critical factor in BC during follow-up.

Age-Related Clusters and Favorable Immune Phenotypes in Young Breast Cancer Patients

Breast cancer (BC) patients aged <40 years at diagnosis experience aggressive disease and poorer survival compared with women diagnosed with BC at 40 to 49 years, but the age-related biology is described to little extent. Here, we explored transcriptional alterations in BC to gain better understanding of age-related tumor biology. We studied a subset of the Bergen in-house cohort (n = 127; age range, 26-49 years) and used the NanoString Breast Cancer 360 expression panel on formalin-fixed paraffin-embedded BC tissue, and publicly available global BC messenger RNA expression data (n = 204; age range, 22-49 years), to explore differentially expressed genes between the young (age <40 years) and older (age 40-49 years) patients. Unsupervised hierarchical clustering was applied to identify gene expression–based patient clusters. We applied established computational approaches to define the PAM50 subtypes, risk of recurrence scores (ROR), and risk groups and to infer the proportions of 22 immune cell types from bulk gene expression profiles of patients aged <50 years at BC diagnosis. Differentially expressed genes and gene sets were investigated using OncoEnrichR and g:Profiler to describe functional profiles and pathway enrichment. We identified 4 age-related patient clusters presenting distinct characteristics of PAM50 subtypes and ROR profiles, which demonstrated independent prognostic value when adjusted for traditional clinicopathologic variables and the known molecular subtypes. Our findings showed better survival than expected in the basal-enriched cluster 2 and in triple-negative and basal-like BC. Deconvolution analyses of immunophenotypes indicated higher levels of M0 and M1 macrophages than M2 macrophages in subsets of young BC. Our approach identifies age-based patient clusters with distinct clinicopathologic profiles, to a large extent overlapping with the PAM50 subtypes, although with independent prognostic values in multivariate survival analyses. The patient clusters provided new insight in the immune cell distribution across tumor subtypes, potentially contributing to survival differences between the clusters and the molecular subtypes and indicating age-related mechanisms improving outcome. Our study confirms the applicability of ROR as a valid prognosticator also in a young BC cohort.

A PET-Surrogate Signature for the Interrogation of the Metabolic Status of Breast Cancers.

Metabolic alterations in cancers can be exploited for diagnostic, prognostic, and therapeutic purposes. This is exemplified by 18F-fluorodeoxyglucose (FDG)-positron emission tomography (FDG-PET), an imaging tool that relies on enhanced glucose uptake by tumors for diagnosis and staging. By performing transcriptomic analysis of breast cancer (BC) samples from patients stratified by FDG-PET, a 54-gene signature (PETsign) is identified that recapitulates FDG uptake. PETsign is independently prognostic of clinical outcome in luminal BCs, the most common and heterogeneous BC molecular subtype, which requires improved stratification criteria to guide therapeutic decision-making. The prognostic power of PETsign is stable across independent BC cohorts and disease stages including the earliest BC stage, arguing that PETsign is an ab initio metabolic signature. Transcriptomic and metabolomic analysis of BC cells reveals that PETsign predicts enhanced glycolytic dependence and reduced reliance on fatty acid oxidation. Moreover, coamplification of PETsign genes occurs frequently in BC arguing for their causal role in pathogenesis. CXCL8 and EGFR signaling pathways feature strongly in PETsign, and their activation in BC cells causes a shift toward a glycolytic phenotype. Thus, PETsign serves as a molecular surrogate for FDG-PET that could inform clinical management strategies for BC patients.

Unveiling Hidden Battles: Exploring the Link Between Breast Cancer Survival and Heart Failure Vulnerability.

This study explores the link between a history of breast cancer and the vulnerability to heart failure. Analyzing data from the National Inpatient Sample (NIS) for women diagnosed with breast cancer between 2016 and 2019 in the US, our research utilized logistic regression, adjusting for demographics, comorbidities, and lifestyle factors, and employed propensity score matching. With 2,276,639 weighted cases, our findings reveal a slight but significant elevation in heart failure risk among the breast cancer cohort, specifically in acute, chronic, and isolated systolic heart failure types. Racial differences were pronounced; Black women with breast cancer showed higher risks for all heart failure types, particularly chronic and systolic, while Asian or Pacific Islander patients had a lower incidence of certain heart failure types. This research underscores a modest increase in heart failure risk post-breast cancer, highlighting the critical need for integrated cardio-oncology care and personalized healthcare approaches to address and mitigate this risk effectively.

Deciphering the Clinical Behaviour of Invasive Lobular Carcinoma of the Breast Defines an Aggressive Subtype.

Invasive lobular carcinoma (ILC), the most common special type of breast cancer (BC), has unique clinical behaviour and is different from invasive ductal carcinoma of no special type (IDC-NST). However, ILC further comprises a diverse group of tumours with distinct features. This study aims to examine the clinicopathological and prognostic features of different variants of ILC, with a particular focus on characterising aggressive subtypes. A large (n = 7140) well-characterised and histologically reviewed BC cohort with treatment and long-term follow-up data was investigated. The cohort was classified based on the WHO classification of tumours into main histological subtypes, including ILC and IDC-NST. ILCs were further classified into variants. Clinicopathological parameters and patient outcomes in terms of BC-specific survival (BCSS) and disease-free survival (DFS) were evaluated. ILC constituted 11% of the cohort. The most common non-classic ILC variants were pleomorphic (pILC) and solid (sILC), constituting 19% of ILC. Compared to classic and related variants (alveolar, trabecular, papillary, and tubulolobular; cILC), pILC and sILC variants were associated with aggressive tumour characteristics. The histologic grade of ILC was an important prognostic variable. The survival patterns identified an aggressive ILC subtype encompassing pILC and high-grade sILC. These tumours, which comprised 14% of the cases, were associated with clinicopathological characteristics of poor prognosis and had high BC-specific death and recurrence rates compared not only to cILC (p < 0.001) but also to IDC-NST (p = 0.02) patients. Contrasting this, cILC patients had significantly longer BCSS and DFS than IDC-NST patients in the first 10 to 15 years of follow-up. Adjuvant chemotherapy did not improve the outcome of patients with aggressive ILC subtypes. pILC and high-grade sILC variants comprise an aggressive ILC subtype associated with poor prognostic characteristics and a poor response to chemotherapy. These results warrant confirmation in randomised clinical trials.

Racial differences in familiarity, interest, and use of integrative medicine among patients with breast cancer

PurposeIntegrative medicine (IM) has received the American Society of Clinical Oncology’s endorsement for managing cancer treatment-related side effects. Little is known about racial differences in familiarity, interest, and use of IM among patients with breast cancer.MethodsPatients with breast cancer enrolled in the Chicago Multiethnic Epidemiologic Breast Cancer Cohort were surveyed regarding familiarity, interest, and use of acupuncture, massage, meditation, music therapy, and yoga. Familiarity and interest, measured by a 5-point Likert scale, was modeled using proportional odds. Use was self-reported, and modeled using binary logistic regression.ResultsOf 1,300 respondents (71.4% White and 21.9% Black), Black patients were less likely than White patients to be familiar with acupuncture (aOR 0.60, 95% CI 0.41–0.87); there were no racial differences in familiarity with massage, meditation, music therapy, and yoga. While there were no differences in interest in acupuncture between Black and White patients (aOR 1.12, 95% CI 0.76–1.65), Black patients were more interested in massage (aOR 1.86, 95% CI 1.25–2.77), meditation (aOR 2.03, 95% CI 1.37–3.00), music therapy (aOR 2.68, 95% CI 1.80–3.99), and yoga (aOR 2.10, 95% CI 1.41–3.12). Black patients were less likely than White patients to have used acupuncture (aOR 0.49, 95% CI 0.29–0.84); but there were no racial differences in use of massage, meditation, music therapy, and yoga.ConclusionBlack patients expressed more interest in IM than their White counterparts; there were no racial differences in IM use, except lower acupuncture use among Black patients. A breast program focused on equity should provide access to these services for patients with breast cancer.

Abstract PO4-18-11: Phase 1 study of the tissue factor-targeting antibody-drug conjugate XB002 in patients with advanced solid tumors (JEWEL-101): Design of the triple-negative and hormone receptor-positive breast cancer expansion cohorts

Abstract Background: Tissue factor (TF) is a transmembrane protein that functions as a factor VIIa receptor, initiating the extrinsic coagulation cascade. TF is aberrantly expressed in multiple solid tumors, including breast cancer (BC), and its expression is associated with disease progression and poor prognosis (van den Berg et al. Blood 2012). Microtubule-targeting agents are a cornerstone of treatment for metastatic BC. XB002 is a novel antibody-drug conjugate (ADC) composed of a high-affinity TF-directed human monoclonal antibody conjugated to the zovodotin linker-payload. Zovodotin consists of an auristatin-based payload and a protease-cleavable linker and is designed to lower off-target deconjugation and improve tolerability compared with other microtubule inhibitor linker-payloads. In preclinical studies, XB002 did not interfere with coagulation and demonstrated antitumor activity with an encouraging safety profile. XB002 is being evaluated in JEWEL-101, an ongoing trial in patients (pts) with advanced solid tumors, including BC. Preliminary results from the dose-escalation stage of JEWEL-101 showed XB002 was well tolerated at multiple dose levels with no bleeding events or treatment-related peripheral neuropathy (PN) and low-grade ocular toxicity (Ulahannan et al. ENA 2022). Presented here is the study design of the tumor-specific expansion stage, including triple-negative BC (TNBC) and hormone receptor-positive BC (HR+ BC) cohorts. Trial design and statistical methods: JEWEL-101 (NCT04925284) is a multicenter, open-label, phase 1 trial evaluating the safety, tolerability, pharmacokinetics (PK), and antitumor activity of XB002 in advanced solid tumors. Single-agent XB002 at the recommended dose will be assessed in the BC expansion cohorts utilizing Simon’s Two-Stage design. Eligibility criteria: The trial will enroll adult pts with TNBC (ER-/PR-/HER-2-negative or low) and HR+ BC (ER+ and/or PR+ and HER-2-negative or low) into 2 separate cohorts. HER-2 negativity is defined as either HER-2 negative or low by local ISH or IHC assessment. For both cohorts, pts must have received 1–3 lines of prior systemic anticancer therapies for locally advanced or metastatic disease. Pts in the HR+ BC cohort must have received prior endocrine therapy and CDK4/6 inhibitor. All pts must have cytologically or histologically and radiologically confirmed BC that is inoperable, locally advanced, metastatic, or recurrent. Documented radiographic progression during or following their last systemic anticancer therapy is required. All pts must also have measurable disease per RECIST 1.1 by investigator assessment, archival (&amp;lt; 2 years) or fresh tumor tissue, ECOG PS 0 or 1, and adequate organ and marrow function. Pts with grade 1 PN are allowed. Concomitant anticoagulation therapy while receiving XB002 is permitted if clinically indicated. Key exclusions are prior use of TF-targeting or auristatin derivate-based ADC; uncontrolled, significant intercurrent or recent illness, including acute or chronic significant ocular disorders; major surgery within 4 weeks; and corrected QT interval calculated by the Fridericia formula &amp;gt;480 ms per ECG. Specific aims: The primary objective of the expansion stage is to evaluate the preliminary efficacy of XB002 by estimating the objective response rate per RECIST 1.1 as assessed by the investigator. Secondary objectives include safety and tolerability, PK, immunogenicity, progression-free survival, duration of response, and overall survival. Accrual: Up to 28 pts will be enrolled into each BC cohort. Enrollment is planned across sites in the US, Europe, and Asia-Pacific. Contact information: Exelixis Clinical Trials, druginfo@exelixis.com, 1-888-393-5494 Citation Format: Susanna Ulahannan, Melissa Johnson, Mia Weiss, Andrae Vandross, Sofia Vidal-Cardenas, Mustafa Syed, Anthony Tolcher. Phase 1 study of the tissue factor-targeting antibody-drug conjugate XB002 in patients with advanced solid tumors (JEWEL-101): Design of the triple-negative and hormone receptor-positive breast cancer expansion cohorts [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO4-18-11.

Abstract PO3-13-11: Quantitative Multiplex Immunofluorescence Assay for TROP2 and HER2 Expression in Breast Cancer: Towards Guiding Patient Selection for Antibody Drug Conjugate Therapies

Abstract Emerging antibody drug conjugate (ADC) therapies targeting human trophoblast cell-surface antigen (TROP2) and human epidermal growth factor receptor 2 (HER2) are transforming the treatment landscape for breast cancer. Sacituzumab govitecan (SG) and trastuzumab deruxtecan (T-DXd) have gained approval for an overlapping set of "HER2-low" metastatic breast cancers, including hormone receptor (HR)-positive HER2 non-amplified and "triple-negative" subtypes. Nevertheless, the optimal selection of patients and treatment sequencing for these ADC therapies remains a clinical challenge. Clinical trial objective response rates to SG are approximately 30%, compared to 30-90% for T-DXd depending on HER2 expression levels. While both drugs are thought to be targeted therapies, the value of measuring the target and the best methods to do so are still not established. We believe that quantitative measurement of TROP2 and HER2 antigen expression levels could establish thresholds for responders, enabling more effective patient selection for ADC therapies. Here, we present a TROP2, high-sensitivity HER2, and cytokeratin (CK) quantitative immunofluorescence (QIF) multiplex assay. Using a ten-cell line standard array and proteomic mass spectrometry, we can convert tumor compartment QIF intensity to protein concentration in fmol/mm2 for tissue specimens. Anti-HER2, anti-TROP2 antibodies, and fluorescence detection systems were titrated and combined to maximize signal-to-noise ratio on our cell line standard array and breast cancer tissue microarrays (TMA). The multiplex assay was designed for automated slide stainers (Leica BOND Rx) and fluorescence slide scanning (Rarecyte CyteFinder II HT). We perform our analyses in QuPath using an image processing plugin developed for automated QIF/IHC analysis (Qymia). Reproducible TROP2 and HER2 QIF scoring (R² &amp;gt; 0.95) was achieved across multiple staining batches using serial sections of breast cancer TMAs and cell standard arrays. This assay has a TROP2 linear range between 0.63 - 9.17 fmol/mm2 (about 1 million TROP2 receptors/cell) and HER2 linear range between 0.09 - 0.565 fmol/mm2 (about 60,000 HER2 receptors/cell). We then applied this multiplex assay to two serial retrospective primary breast cancer cohorts from Yale University to quantitatively measure TROP2 and HER2 expression (338 clinical cases). We find a weak negative correlation between TROP2 and HER2 expression in our breast cancer cohorts (Pearson r = -0.14, p = 0.0097, n = 338). TROP2 expression levels were above the limit of detection (LOD) in 90.2% of cases, with 4.1% exceeding the limit of linearity (LOL), and a mean TROP2 expression of 4.05 fmol/mm2. For HER2, 67.2% of cases were above the LOD, with 7.1% exceeding the LOL, and a mean HER2 expression of 0.186 fmol/mm2. Both TROP2 and HER2 were below the LOD in 3.0% of cases, which we define as “negative”. We found 29.9% expressed TROP2 and were HER2-negative, and 6.8% expressed HER2 and were TROP2-negative. Our future studies will aim to quantitatively define expression thresholds for T-DXd and SG response with the goal to produce a clinical grade assay for ADC patient selection and determine the value of the assay to help select which ADC to give first. HER2 and TROP2 protein expression summary in Yale breast cancer cohort Table 1: Summary of HER2 and TROP2 protein expression levels in serial retrospective primary breast cancer cohort of 338 cases using our high-sensitivity HER2 and TROP2 multiplex immunofluorescent assay Citation Format: Charles Robbins, Mengni He, Revekka Khaimova, Katherine Bates, Nay Nwe Nyein Chan, Daniel Liebler, Regan Fulton, David Rimm. Quantitative Multiplex Immunofluorescence Assay for TROP2 and HER2 Expression in Breast Cancer: Towards Guiding Patient Selection for Antibody Drug Conjugate Therapies [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO3-13-11.

Abstract PO4-15-03: Quantitative Measurement of TROP2 via Chromogenic Immunohistochemistry in Breast Cancer

Abstract Sacituzumab govitecan (SG) is an antibody-drug conjugate that targets human trophoblast cell-surface antigen 2 (TROP2), which is expressed in over 90% of breast cancer cases (Zaman et al, 2019). By delivering the cytotoxic SN-38 (topoisomerase I inhibitor) to TROP2 expressing breast cancer cells, SG showed promising antitumor activities in clinical trials and is now an approved treatment for triple-negative breast cancer (TNBC) and hormone receptor (HR)-positive HER2-negative breast cancer in the metastatic setting. Despite the prevalent expression of TROP2 in breast cancer, the objective response rates reported from clinical trials were about 30%, indicating the need for a diagnostic test that can identify which patients are likely to benefit from therapy. Although the drug is approved without a companion diagnostic assay, recent data from the TROPiCS-02 trial has shown that TROP2-low (H-score &amp;lt; 100) showed a non-significant hazard ratio for benefit from SG. In the same study, patients treated with SG with H-score &amp;gt;100 showed a significant hazard ratio for benefit compared to physician’s choice (Tolaney et al, ASCO 2023). This suggests that TROP2 expression level is associated with SG response and that a threshold for TROP2 expression level may aid patient selection. Although over 90% of breast cancer patients were considered TROP2-positive by IHC, the expression level of TROP2 was never quantitatively assessed in large breast cancer cohorts. Here we describe a quantitative chromogenic immunohistochemistry (IHC) assay with a cell line standard. Mass spectrometry was used to measure TROP2 peptide concentrations in the six standard cell lines, and the correlation between the mass spectrometry and IHC data for each cell line was then used to convert chromogenic signals to concentrations of TROP2 protein (fmol/mm2). The antibody used in this assay was rigorously validated, and the antibody concentration was optimized for the best signal-to-noise ratio. The optical density (OD) of chromogenic staining was measured using QuPath 0.4.3 (Qymia extension) by identifying the tumor area via object classifiers and manual editing and then calculating the area-normalized sum of OD. Collectively, this assay can measure up to 29.1 fmol/mm2 of TROP2. By applying this assay to two serial retrospective primary breast cancer cohorts from Yale University, we quantitatively measured TROP2 expression levels in 332 clinical cases. Not surprisingly, over 90% of cases showed some chromogenic signal, with a median TROP2 concentration of 2.1 fmol/mm2 and a maximum of 10.5 fmol/mm2. TROP2 expression levels showed no significant association with clinicopathologic characteristics including race, stage, BRCA mutation status, molecular subtype, HER2 IHC levels, and outcome. Further work is underway to optimize the assay toward the goal of determination of whether there is a quantitatively definable threshold for TROP2 expression below which patients are unlikely to benefit from SG or other TROP2-targeted therapies. Citation Format: Mengni He, Matthew Liu, Thazin Aung, Sneha Burela, Katherine Bates, Charles Robbins, David Rimm. Quantitative Measurement of TROP2 via Chromogenic Immunohistochemistry in Breast Cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO4-15-03.