Outcome In Breast Cancer Patients Research Articles

Measuring cfDNA integrity as a biomarker for predicting neoadjuvant chemotherapy response in breast cancer patients: a pilot study.

Circulating cell-free DNA (cfDNA) is a promising biomarker for predicting treatment response and disease outcomes in Breast Cancer (BC) patients undergoing neoadjuvant chemotherapy (NAC). To determine if cfDNA originates from tumors, matching tumor and cfDNA gene mutations are necessary, often requiring tumor DNA sequencing. We assessed plasma cfDNA integrity by measuring concentrations and ratios of larger-to-smaller Alu DNA fractions as a potential biomarker, eliminating the need for prior tumor sequencing. We included patients with localized and/or locally advanced BC receiving standard NAC alone or in combination with immunotherapy and/or anti-HER2 targeted therapy. Blood samples were collected before treatment, every 2 weeks during treatment, and before surgery. Of the 38 evaluated patients, only 28 completed the protocol and underwent surgery after NAC. Seven patients (25%) achieved a pathologic complete response (pCR). We found that cfDNA integrity (cfDNAI) levels at 15days after starting NAC were significantly higher in patients who achieved pCR (p = 0.045) and correlated significantly with Disease-Free Survival (DFS) in univariate analysis (p = 0.0371). Evaluation of cfDNAI 2 weeks after NAC initiation appears to be an early biomarker for tumor pCR and DFS. Measuring Alu fragments of different lengths may replace techniques requiring prior tumor sequencing to measure ctDNA, reducing costs and complexity of cfDNA serial measurements in BC patients undergoing NAC.

Functional hemodynamic imaging markers for the prediction of pathological outcomes in breast cancer patients treated with neoadjuvant chemotherapy.

Achieving pathologic complete response (pCR) after neoadjuvant chemotherapy (NACT) is a significant predictor of increased likelihood of survival in breast cancer patients. Early prediction of pCR is of high clinical value as it could allow personalized adjustment of treatment regimens in non-responding patients for improved outcomes. We aim to assess the association between hemoglobin-based functional imaging biomarkers derived from diffuse optical tomography (DOT) and the pathological outcome represented by pCR at different timepoints along the course of NACT. Twenty-two breast cancer patients undergoing NACT were enrolled in a multimodal DOT and X-ray digital breast tomosynthesis (DBT) imaging study in which their breasts were imaged at different compression levels. Logistic regressions were used to study the associations between DOT-derived imaging markers evaluated after the first and second cycles of chemotherapy, respectively, with pCR status determined after the conclusion of NACT at the time of surgery. Receiver operating characteristic curve analysis was also used to explore the predictive performance of selected DOT-derived markers. Normalized tumor HbT under half compression was significantly lower in the pCR group compared to the non-pCR group after two chemotherapy cycles (). In addition, the change in normalized tumor upon reducing compression from full to half mammographic force was identified as another potential indicator of pCR at an earlier time point, i.e., after the first chemo cycle (). Exploratory predictive assessments showed that AUCs using DOT-derived functional imaging markers as predictors reach as high as 0.75 and 0.71, respectively, after the first and second chemo cycle, compared to AUCs of 0.50 and 0.53 using changes in tumor size measured on DBT and MRI. These findings suggest that breast DOT could be used to assist response assessment in women undergoing NACT, a critical but unmet clinical need, and potentially enable personalized adjustments of treatment regimens.

Simultaneous integrated boost intensity-modulated radiotherapy post breast-conserving surgery: clinical efficacy, adverse effects, and cosmetic outcomes in breast cancer patients.

Simultaneous integrated boost intensity-modulated radiotherapy (SIB-IMRT) is an innovative technique delivering a higher dose to the tumor bed while irradiating the entire breast. This study aims to assess the clinical outcomes, adverse effects, and cosmetic results of SIB-IMRT following breast-conserving surgery in breast cancer patients. We conducted a retrospective analysis of 308 patients with stage 0-III breast cancer who underwent breast-conserving surgery and SIB-IMRT from January 2016 to December 2020. The prescribed doses included 1.85 Gy/27 fractions to the whole breast and 2.22 Gy/27 fractions or 2.20 Gy/27 fractions to the tumor bed. Primary endpoints included overall survival (OS), local-regional control (LRC), distant metastasis-free survival (DMFS), acute and late toxicities, and cosmetic outcomes. The median follow-up time was 36 months. The 3-year OS, LRC, and DMFS rates were 100%, 99.6%, and 99.2%, respectively. Five patients (1.8%) experienced local recurrence or distant metastasis, and one patient succumbed to distant metastasis. The most common acute toxicity was grade 1-2 skin reactions (91.6%). The most common late toxicity was grade 0-1 skin and subcutaneous tissue reactions (96.7%). Five patients (1.8%) developed grade 1-2 upper limb lymphedema, and three patients (1.1%) had grade 1 radiation pneumonitis. Among the 262 patients evaluated for cosmetic outcomes at least 2 years post-radiotherapy, 96.9% achieved excellent or good results, while 3.1% had fair or poor outcomes. SIB-IMRT after breast-conserving surgery in breast cancer patients demonstrated excellent clinical efficacy, mild acute and late toxicities, and satisfactory cosmetic outcomes in our study. SIB-IMRT appears to be a feasible and effective option for breast cancer patients suitable for breast-conserving surgery.

Impact of the COVID-19 pandemic on breast cancer patient pathways and outcomes in the United Kingdom and the Republic of Ireland - a scoping review.

The COVID-19 pandemic brought unplanned service disruption for breast cancer diagnostic, treatment and support services. This scoping review describes these changes and their impact in the UK and the Republic of Ireland based on studies published between January 2020 and August 2023. Thirty-four of 569 papers were included. Data were extracted and results thematically organized. Findings include fewer new cases; stage shift (fewer early- and more late-stage disease); and changes to healthcare organization, breast screening and treatment. Examples are accepting fewer referrals, applying stricter referral criteria and relying more on virtual consultations and multi-disciplinary meetings. Screening service programs paused during the pandemic before enacting risk-based phased restarts with longer appointment times to accommodate reduced staffing numbers and enhanced infection-control regimes. Treatments shifted from predominantly conventional to hypofractionated radiotherapy, fewer surgical procedures and increased use of bridging endocrine therapy. The long-term impact of such changes are unknown so definitive guidelines for future emergencies are not yet available. Cancer registries, with their large sample sizes and population coverage, are well placed to monitor changes to stage and survival despite difficulties obtaining definitive staging during diagnosis because surgery and pathological assessments are delayed. Multisite longitudinal studies can also provide guidance for future disaster preparedness.

Abstract PO4-16-06: From Real-World Data to Improved Outcomes: Examining the Impact of Trastuzumab Disparities on Pathological Complete Response and Long-Term Survival in HER-2 Positive Breast Cancer Patients within the Brazilian Public Health System

Abstract Introduction: Equitable access to healthcare is a fundamental principle of public health, aiming to ensure that all individuals have the opportunity to receive effective treatments. However, disparities in access to healthcare still persist in many countries, including Brazil. These disparities can have significant impacts on the health and well-being of patients, particularly in the case of breast cancer treatment. Neoadjuvant chemotherapy (NAC) has been increasingly used for the treatment of breast cancer, encompassing conditions ranging from locally advanced tumors to early-stage triple-negative and HER-2 positive tumors. Objectives: The aim of this study is to evaluate the impact of disparities in the use of trastuzumab (Herceptin) within the Brazilian public health system on pathological complete response (pCR), overall survival (OS), and disease-free survival (DFS). We aim to investigate whether variations in access to trastuzumab treatment influence the achievement of pCR and impact long-term survival outcomes in breast cancer patients. Methods: This retrospective, multicenter cohort study included female patients over 18 years of age with a diagnosis of non-metastatic breast cancer undergoing NAC. pCR was defined as the absence of residual invasive or in situ tumor in the breast and axilla. As an exploratory real-world data study, no confirmatory hypothesis was established, thus no corrections for multiple comparisons were necessary. Overall survival (OS) and disease-free survival (DFS) were estimated using the Kaplan-Meier method, calculated at five years. The study was approved by the Research Ethics Committee with registration number CAAE 64633422.4.0000.5463. Results: Between 2011 and 2020, a total of 1,891 patients were included in the study, of whom 454 (22.9%) were HER-2 positive. The pCR rate was 25.7%. Trastuzumab was accessed by 291 (64.1%) patients (p < 0.001). Among those who received trastuzumab, pCR was observed in 105 (36.1%) patients, compared to 12 (7.6%) in those who did not have access to trastuzumab (p < 0.001). OS in HER-2 positive patients was 90.1% with pCR and 64.5% without pCR (log-rank p < 0.001), while DFS was 89.2% with pCR and 68.2% without pCR (log-rank p = 0.003). Evaluating OS and DFS in patients who received trastuzumab versus those who did not, OS with trastuzumab and pCR was 94.3% and without pCR was 89.5% (log-rank p < 0.001); OS without trastuzumab and pCR was 83.3% and without pCR was 58.2% (log-rank p < 0.001). DFS in patients who received trastuzumab and achieved pCR was 94.5% and without pCR was 90.5% (log-rank p = 0.05), whereas without trastuzumab and pCR was 79.9% and without pCR was 62.1% (log-rank p = 0.001). Conclusion: These findings underscore the significant impact of disparities in trastuzumab utilization within the Brazilian public health system on pCR rates and long-term survival outcomes in HER-2 positive breast cancer patients. Access to trastuzumab was associated with higher pCR rates and improved overall and disease-free survival rates. Ensuring equitable access to targeted therapies is crucial for improving treatment response and long-term outcomes in breast cancer patients. Table 1 Clinicopathological characteristics of patients Legend: AJCC, American Joint Committee on Cancer; IDC, invasive ductal carcinoma; ILC, invasive lobular carcinoma; HR hormonal receptor. Table 2 - NAC schemas and correlation with pCR. AC-T, doxorubicin + cyclophosphamide – taxane; AC-TH, doxorubicin + cyclophosphamide – taxane+herceptin. Citation Format: Marcelo Antonini, Andre Mattar, Gabriel Pannain, Fernanda Grace Bauk Richter, Andressa Amorim, Marina Diogenes, Odair Ferraro, Luiz Gebrim, Reginaldo Coelho Lopes, Juliana Real. From Real-World Data to Improved Outcomes: Examining the Impact of Trastuzumab Disparities on Pathological Complete Response and Long-Term Survival in HER-2 Positive Breast Cancer Patients within the Brazilian Public Health System [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 PO4-16-06.

Abstract PO2-15-09: Immune related cell fraction in peripheral blood and outcomes of advanced breast cancer patients treated with Eribulin

Abstract Background: Eribulin prolongs overall survival (OS) of patients with advanced breast cancer, and an ad-hoc analysis of the EMBRACE trial showed that baseline absolute lymphocyte count (ALC) was a predictor of OS prolongation. It has been suggested that eribulin improves the immune response to the tumor by improving the hypoxic environment through remodeling of local tumor vessels and reducing hypoxic stress, leading to OS prolongation. However, the details of the immune response mediated by eribulin remain to be fully elucidated. CD8+ cells attack cancer cells as cytotoxic T cells, while regulatory T cells (Tregs) and myeloid-derived suppressor cells (MDSCs) suppress activated T cells that attack cancer cells. In this study, we focused on CD8+ cytotoxic T cells, Tregs, MDSCs, and CD4-CD25-FoxP3+ cells in peripheral blood, analyzed the changes of those immune cells before and after eribulin treatment, and examined the effects on the outcomes of breast cancer patients. Methods: Nineteen patients with advanced or recurrent breast cancer treated with eribulin from April 2021 to May 2023 at our hospital were included. Peripheral blood was collected before drug administration as the first treatment (pre-treatment) and before drug administration in the second course (post-treatment), and the cell fractions, including CD4+ cells, CD8+ cells, CD4+CD25+FoxP3+ Tregs, CD11b+CD14+CD33+ MDSCs, and CD4-CD25-FoxP3+ cells, were analyzed by flow cytometry. The cutoff value for ALC was set at 1000 and NLR at 3.0, and each cell fraction was set to its respective median. Kaplan-Meier plots and logrank tests for progression-free survival (PFS) or OS were applied. Results: CD4+ cells were significantly lower post-treatment compared to pre-treatment (p=0.0140). Further, Tregs were significantly lower post-treatment compared to pre-treatment (p=0.0258). There were no significant changes in the levels of CD8+ cells, MDSCs, and CD4-CD25-FoxP3+ cells between pre- and post-treatment. We examined the association between each cell fraction and ALC or NLR, and found that CD4-CD25-FoxP3+ cells were significantly higher in cases with high NLR (p=0.0110). Analysis of the association between each cell fraction and prognosis at pre-treatment revealed that the high CD8+ cell group had significantly better PFS and OS than the low CD8+ cell group (p=0.0129 and p=0.0077, respectively). Interestingly, the high CD4-CD25-FoxP3+ cell group had significantly worse PFS than the low CD4-CD25-FoxP3+ cell group (p=0.0026). Conclusion: In the current study, Tregs in the peripheral blood of breast cancer patients significantly decreased after eribulin treatment, suggesting that eribulin may improve the immune microenvironment by suppressing immunosuppressive cells in cancer, including Tregs. In addition, the CD4-CD25-FoxP3+ cell fraction may serve as a biomarker for eribulin therapy, and further studies are needed to elucidate the details, including analysis of the constituent cells within the fraction. Citation Format: Masayuki Nagahashi, Ayako Bun, Mamiko Kuroiwa, Miki Komatsu, Sayaka Urano, Yukie Fujimoto, Aoi Oshiro, Ayumu Mitsuyoshi, Haruka Kanaoka, Akira Hattori, Reiko Fukui, Tomoko Higuchi, Arisa Nishimukai, Keiko Murase, Yuichi Takatsuka, Yasuo Miyoshi. Immune related cell fraction in peripheral blood and outcomes of advanced breast cancer patients treated with Eribulin [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 PO2-15-09.

Abstract PO1-22-03: Radiation Toxicity and Treatment Outcomes in Breast Cancer Patients with ATM Pathogenic and VUS Mutations: Implications for Personalized Therapy

Abstract Introduction: Previous studies have shown that ATM (ataxia-telangiectasia mutated) mutations may be associated with increased radiation sensitivity and altered treatment response. However, there is a limited understanding of the clinical implications and optimal management strategies for breast cancer patients with ATM mutations receiving radiotherapy (RT). The aim of our study is to assess the impact of ATM mutations on radiation response and treatment outcomes in breast cancer patients undergoing RT. Material and Methods: A total of 79 female patients diagnosed with breast cancer were included in the study, with 31 (39.3%) having pathogenic (P) and likely pathogenic (LP) variants (all of the variants were heterozygous) and 48 (60.8%) having VUS variants detected through whole ATM gene sequencing screening for patients in accordance with NCCN clinical practice guideline. Statistical analysis, including descriptive, graphical, and inferential methods, such as the Kolmogorov-Smirnov test, Mann-Whitney U Test, and Chi-square tests, was conducted using SPSS version 25.0 to evaluate the normal distribution of continuous variable scores and perform quantitative and qualitative comparisons between groups at a 95% confidence level (p < 0.05). Results: The median age of the patients was 44 years (range: 24-74), with 75% of them being 50 years old or younger .The rate of breast cancer in patients with VUS variants was significantly higher in those aged 50 and below compared to those with P/LP variants (83% vs. 61%, p=0.028). There was no statistically significant difference in clinical stage, tumour histological type, and molecular subtype classification based on ATM gene variant type (P/LP vs. VUS) among the patients (p>0.05), but the rate of high tumour grade was significantly higher in the VUS variant group (65% vs. 40%, p=0.034). The rate of patients who received RT was 87%, with 26 patients receiving radiation to the breast or chest wall and 43 patients receiving additional regional lymph node irradiation. There were no statistically significant differences in surgical and systemic treatment types and RT dose based on ATM gene variant type (P/LP vs. VUS) (p>0.05). Among the patients who received RT, 33 (48%) experienced early-stage skin reactions, and 15 (22%) experienced late-stage skin reactions according to Common Terminology Criteria for Adverse Events (CTCAE) v5. No Grade 3, 4 and 5 early and late toxicity were observed . The rate of early (83% vs. 23%; p< 0.001) and late (35% vs. 13%; p=0.029) skin reactions was significantly higher in the P/LP variant group compared to the VUS variant group. Grade I lymphedema was observed in 2 (2.5%) patients, 1 (3.2%) in the P/LP group and 1 (2.1%) in the VUS group (p>0.05). Among the 23 patients who underwent breast reconstruction, 1 (4%) had implant revision and 1 (4%) experienced implant loss, both of which were observed in the pathogenic variant group (p>0.05). Conclusion: Limited clinical data exists on RT toxicity in breast cancer patients with ATM gene mutations, and clear guidelines for decision-making are lacking. Our study revealed higher rates of acute and chronic skin reactions in the P/LP variant group, highlighting the need for further investigation into the impact of these variants on treatment outcomes and patient management. However, it is crucial to manage these reactions effectively and not allow them to hinder treatment. Additional research and interventions are warranted to better understand and address these reactions, aiming to enhance the overall treatment experience and outcomes for patients with ATM gene mutations. Citation Format: Evrim Tezcanli, Seda Eroz, Ugur Ozbek, Ahmet Yesilyurt, CIHAN URAS, Nuran Bese. Radiation Toxicity and Treatment Outcomes in Breast Cancer Patients with ATM Pathogenic and VUS Mutations: Implications for Personalized Therapy [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 PO1-22-03.

Abstract PO2-12-10: Age-specific outcomes in breast cancer patients treated with aromatase inhibitors - A national inpatient sample database analysis

Abstract Background: This study aims to investigate the age-specific outcomes of breast cancer patients undergoing aromatase inhibitors therapy. Currently, no research exists on the age-specific differences in outcomes for this patient population. This study seeks to fill this knowledge gap and provide valuable insights into the various outcomes of these patients. Methods: This retrospective study analyzed hospitalization data from the National Inpatient Sample (NIS) between January 2016 and December 2019 using STATA/BE 17.0 for statistical analysis. It focused on breast cancer patients treated with aromatase inhibitors, evaluating outcomes like mortality, length of stay, charges, and clinical outcomes. We used univariate regression and logistic analysis, with ICD-10 codes utilized for data classification. Results: A total of 5,994 weighted hospitalizations were identified, consisting of breast cancer patients being treated with aromatase inhibitors. For patients aged below 65 (n=1,919), the inpatient mortality rate was 1.8% (n=35), while for patients aged 65 and above (n=4,075), it was slightly higher at 2.3% (n=94). However, there was no statistically significant difference in inpatient mortality between the two age groups (adjusted odds ratio [aOR] = 1.21 [0.82-1.78], p=0.339). The average length of stay (LOS) was similar for both age groups, with patients below 65 having a mean LOS of 4.75 days and those aged 65 and above having a mean LOS of 4.71 days. Total charges ($) in the younger population ( < 65) were incurred at a mean of $60,782.73 (56,764.18-64,801.27), compared to lesser charges in the elderly at a mean of $54,734.38 (52,339.83-57,128.94). The occurrence of pathological fractures was higher in patients below 65, with a rate of 1.6% (n=31), compared to 0.8% (n=33) in patients aged 65 and above (aOR = 0.47 [0.28-0.78], p=0.004). Regarding venous thromboembolism (VTE), the occurrence was 5.5% (n=105) in patients below 65 and 4.8% (n=195) in patients aged 65 and above. There was no significant difference between the two age groups (aOR = 0.86 [0.68-1.10], p=0.237). The occurrence of acute cerebrovascular accidents (CVA) was 0.6% (n=11) in patients below 65 and 1.6% (n=65) in patients aged 65 and above, with an aOR of 2.58 (1.38-4.80), indicating a significantly higher likelihood of CVA in the older age group (p=0.003). Patients aged 65 and above had a higher occurrence of myocardial infarction (MI) compared to patients below 65, with rates of 2.1% (n=85) and 0.1% (n=2), respectively. The aOR for MI was 2.35 (1.39-3.98), indicating a significantly higher likelihood of MI in the older age group (p=0.001). There was no statistically significant difference in the occurrence of hypertensive crisis (HTN crisis) between the two age groups (aOR=1.47 [0.93-2.34], p=0.09). Conclusion: Among breast cancer patients receiving aromatase inhibitors, there was no significant difference in in-patient mortality between those aged below 65 and those aged 65 and above. Both age groups had similar lengths of stay and charges incurred. There was no statistically significant difference in VTE and HTN crisis odds. However, patients below 65 had a higher occurrence of pathological fractures, while patients aged 65 and above had a higher likelihood of acute cerebrovascular accidents and myocardial infarction. Further guidelines must be established to improve inpatient morbidity and mortality in this patient population. Breast cancer patients on aromatase inhibitors therapy Citation Format: Rushin Patel, Akshit Chitkara, Zalak Patel, Mrunal Patel, Darshil Patel, Himanshu Kavani, FNU Anamika, Femina Patel. Age-specific outcomes in breast cancer patients treated with aromatase inhibitors - A national inpatient sample database analysis [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 PO2-12-10.

Abstract PO2-06-03: Meta-Analysis of Clinical Characteristics and Outcomes in Breast Cancer Patients with Visceral Crisis

Abstract Background: Recent advancements in novel therapeutics have resulted in improved survival over the last decade for patients with metastatic breast cancer, but there remain subsets of patients who experience disproportionately poor outcomes. Patients with visceral crisis (VC), defined by the 5th ESO ESMO as the presence of visceral metastasis with severe organ compromise and/or rapid progression, are often excluded from clinical trials of novel therapeutics. This is despite patients with VC having poorer clinical outcomes and a lack of guidelines consensus on best therapeutic practices. Thus, we sought to better characterize this patient cohort via a meta-analysis to elucidate clinical characteristics and treatment options. Methods: We searched MEDLINE, Embase, Cochrane, Scopus and other sources, from each database's inception to March 2023. The search strategy was designed and conducted by an experienced librarian with input from the study's principal investigator. Controlled vocabulary supplemented with keywords was used to search for patients with breast cancer in visceral crisis. Outcomes of interest included mortality and progression at different time points. Meta-analysis was conducted using the random-effects model. Results: The studies matching our initial inquiry was 154. After evaluation for patient number, and VC related outcomes, 16 studies (12 abstract only) met initial criteria. After data extraction, 12 studies were excluded due to insufficient outcomes delineated by VC. The treatment period was 01/2008 until 01/2022. The mean age at diagnosis of VC was 53.9 with a total of 6404 patients, 6259 were hormone positive, 41 Her2 positive and 87 triple negative. The type of VC included 212 liver dysfunction, 84 respiratory dysfunction, 40 with bone marrow dysfunction, 4 with SVC syndrome, and 43 with meningeal disease (VC type is not reported in every study). The treatments were varied and included multiple platinum doublets, CDK4/6 with endocrine therapy, platinum with bevacizumab, endocrine monotherapy and Her-2 targeted agents. Unfortunately, the number of patients per treatment group or VC type is not enough for targeted outcome analysis. The proportion of patients who progressed at 1, 6, 12 and 18 months were 0.17, 0.64, 0.95 and 0.91 respectively (2 studies Yang et al and Funasaka et al). Mortality assessed as proportion who expired at 1, 6, 12 and 18 months at 0.07, 0.44, 0.64 and 0.77 respectively (3 studies Yang et al, Funasaka et al and Franzoi et al) and at 24 months 0.89 in 4 studies (Yang et al, Funasaka et al, Dawood et al and Franzoi et al) (Table 1). Conclusions In this systematic review, we clearly demonstrate a lack of clinical trial data available to demonstrate specific outcomes based on chemotherapy, visceral crisis type or targeted treatment. The prognosis, however, is consistently poor with mortality at 64 percent by 12 months. Thus, further studies are needed to guide best treatment strategies that address both the poor clinical outcomes and therapeutic toxicities for patients with VC. Clinical trial groups and regulatory bodies overseeing new drug development for breast cancer should consider specific arms for patients with VC, instead of targeted exclusion from trials, as this strategy has proven effective in expansion of therapeutics for other challenging breast cancer subtypes. Table 1 Table 1: Proportion of progression and mortality. Progression studies include Yang et al 2022, Funasaka et al 2021. Mortality studies at 1, 6 and 12 months Yang et al 2022, Funasaka et al 2021 and Franzoi et al 2021. Mortality studies at 24 months Yang et al 2022, Funasaka et al 2021, Franzoi et al 2021, Dawood et al 2021. Citation Format: Michael Auster, Raed Benkhadra, Sophia Lee, Tamarah Aldawoodi, Larry Prokop, Tarek Nayfeh, Paromita Datta, Kate Lathrop. Meta-Analysis of Clinical Characteristics and Outcomes in Breast Cancer Patients with Visceral Crisis [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 PO2-06-03.

Abstract PO4-27-01: COVID-19 Vaccination Behavior and Outcomes in Breast Cancer Patients in comparison with other Cancer types

Abstract Background: Cancer(ca) is a known risk factor for severe COVID-19 (C19) disease, related morbidity, and mortality. Ca patients (pts) were largely excluded from clinical trials evaluating the safety and efficacy of the 3 FDA-approved C19 vaccines (vax). Breast cancer (Bca) is the most commonly diagnosed non-skin ca, and accounts for ~ 30% of all new female cancers each year. The pandemic has led to disruptions in Bca care including screening, diagnosis, treatment, and follow-up which will likely have an impact on Bca mortality. We aim to study behavior and outcomes regarding C19 vax in Bca pts comparison to non-Bca pts. Methods: In our prospective and observational single center study; adult ca pts (18-89 years) seen in clinics from Nov 2021-Sept 2022 were randomly interviewed using telephone surveys after a verbal consent. Type of ca and therapy data were collected from medical records. The survey included C19 disease status, vax status positive (+) or negative (-), reason for vax status, side effects (s.e), and their perspective on impact on ca Rx or ca progression. The primary objective was to identify the rate of vaccination in adult ca pts. Secondary objectives were to quantify C19 vax acceptance vs. hesitance, identify s.e of C19 vax and effect of C19 vax on outcomes in Bca and non-Bca pts. Results: N=170 [Bca 45 (26.5%) and non-Bca 125 (73.5%)]. Among Bca pts: 40 (88.9%) were ER+, 34 (75.5%) PR+, and 9 (20%) HER2+. Of them, 20 (44.4%) pts received cytotoxic chemotherapy and 39 (86.7%) pts received hormonal therapy alone. Refer to Table 1 for key outcomes data. Top 3 risk factors for serious C19+ in Bca pts were age >65yr (42.2%), BMI >30 (42.2%) and smoking (24.4%); and in non Bca pts: age >65yr (52%), BMI >30 (34.4%) and immunocompromised state (23.2%). Top 3 reasons for C19 vax (+) in Bca pts: protection against C19+ for self (82.2%), for others (37.8%) and provider recommendation (46.7%). The main reasons for vax hesitancy in C19 vax (-) Bca pts: fear of side effects (4.4%), prior C19 infection (4.4%) and don’t trust the research behind it (2.2%). The common s.e of C19 vax in Bca pts were fatigue (40%), injection site inflammation (35.6%) and body aches (31.1%). Also, 13.3% of Bca pts developed lymphadenopathy. A total of 71.1% Bca pts developed ‘minor s.e’ from C19 vax, compared to 33.1% in non-Bca pts (p=0.0001). However, none of Bca pts reported progression of the disease or delay in cancer Rx or outcome due to C-19 vax. Conclusion: Majority of the Bca pts were vaccinated against C19 and tolerated it well. Even though significantly higher number of Bca pts had side effects, they were minor and did not impact Bca outcomes. Oncologists should discuss the importance of C19 vax in the context of ca. Table. Citation Format: Hyma Polimera, Emma Guare, Lauren Pomerantz, Monali Vasekar, Junjia Zhu, Monika Joshi. COVID-19 Vaccination Behavior and Outcomes in Breast Cancer Patients in comparison with other Cancer types [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 PO4-27-01.

Abstract PO1-22-10: Long term outcomes of breast cancer patients with local recurrence after mastectomy undergoing immediate breast reconstruction: A retrospective multi-institutional study of 4153 cases

Abstract Background: The number of breast cancer patients in Japan undergoing immediate breast reconstruction (IBR) has increased and the postoperative follow-up period has been extended. This study was conducted to clarify the clinical aspects of and factors associated with local recurrence (LR) after IBR. Methods: This was a multicenter study which included 4153 early breast cancer patients who underwent IBR. Clinicopathological characteristics were examined and factors potentially contributing to LR were analyzed. Risk factors for LR were examined separately for non-invasive and invasive breast cancers. Results: The median follow-up period was 75 months. The 7-year LR rates were 2.1% and 4.3% for non-invasive and invasive cancers, respectively (p < 0.001). The proportions of LR detected by palpation, subjective symptoms, and ultrasonography were 40.0%, 27.3%, and 25.9%, respectively. Overall, 75.7% of LR were solitary, and 92.7% of these cases had no further recurrences during the observational period. Multivariate analysis of LR for invasive cancer showed that skin-sparing mastectomy (SSM) or nipple-sparing mastectomy (NSM), the presence of lymphovascular invasion, cancer at the surgical margin, and not receiving radiation therapy were factors related to LR. The 7-year overall survival rates of the patients with LR and non-LR of invasive cancers were 92.5% and 97.3%, respectively, (p=0.002). Conclusions: The rate of LR after IBR was acceptably low and IBR can thus be performed safely for early breast cancer patients. Invasive cancer, SSM/NSM, lymphovascular invasion, and/or cancer at the surgical margin should prompt awareness of the possibility of LR. Citation Format: Akiko Ogiya, Naomi Nagura, Ayaka Shimo, Hiroko Nogi, Kazutaka Narui, Hirohito Seki, Hiroki Mori, Shinsuke Sasada, Makoto Ishitobi, Naoto Kondo, Chikako Yamauchi, Kohei Akazawa, Tadahiko Shien. Long term outcomes of breast cancer patients with local recurrence after mastectomy undergoing immediate breast reconstruction: A retrospective multi-institutional study of 4153 cases [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 PO1-22-10.

Abstract PO3-06-04: Clinical Features and Survival Outcomes of Oligometastatic Breast Cancer Patients: The Mayo Clinic Experience

Abstract Background The current definition, prognosis, and optimal treatment (tx) for oligometastatic breast cancer (OMBC) are not fully known. With advances in multimodality breast cancer (BC) tx and overall improvement in patient (pt) outcomes, it is important to identify baseline pt factors that confer better prognosis in OMBC and assess the impact of local/regional tx and metastasis (mets)-directed tx on survival outcomes. Methods We reviewed 105 Mayo Clinic pts with OMBC (up to 5 mets) from 2003 to 2021. Pts were excluded from analysis if they were misidentified as having OMBC (n=6), did not have a primary breast mass (n=1), developed de novo BC during tx (n=1), or were lost to follow up (n=2). Categorical variables were summarized as counts. Continuous variables were reported as medians. Kaplan-Meier method was used to estimate survival and the time from diagnosis to next tx at 1, 3, and 5 years. Log-rank test was used to compare survival rates between baseline factors. Univariate Cox proportional hazards models were performed on both baseline and time-dependent factors. All tests were two-sided with p-value < 0.05 considered statistically significant. Results Total pts included were 95. Median age was 49 (range, 26-86), most (93.6%) pts were White, and 46.8% were postmenopausal. Invasive ductal carcinoma (89.5%) was the most common BC type. Median survival was 10.8 years; 1-, 3-, and 5-year survival rates were 98.9%, 87.7%, and 81%, respectively. 58 pts (61.1%) required a change in tx due to disease progression. No significant survival difference was observed in pre- vs. postmenopausal pts (p=0.71) or in groups based on hormone receptor and/or human epidermal growth factor receptor 2 status. 47 pts (49.5%) received local/regional tx; no significant difference in survival (HR 0.57, 95% CI 0.23-1.40; p=0.217) or time to next tx (HR 0.67, 95% CI 0.39-1.15; p=0.144) was seen in this subgroup. Of these pts, 36 (76.6%) received neoadjuvant chemotherapy and/or immunotherapy, 5 of whom (10.6%) also started endocrine tx preoperatively. Overall, 11/47 pts (23.4%) received neoadjuvant endocrine tx. 20 pts received systemic tx without eventual surgery, and 5 pts got palliative radiation (RT). Biopsy-confirmed mets were noted in 76 pts (80%), with bone-only mets in 50%, 30 pts (31.6%) with viscera-only mets and 7 pts (7.4%) with both bone and visceral mets. 18 pts had suspected mets on imaging but did not undergo biopsy. The hazard of death was 6.34 times higher in pts with both bone and visceral mets than those with bone-only mets (p=0.008). Pts with viscera-only mets had higher survival at 2 and 3 years than pts with bone-only or both bone and visceral mets (p=0.093). Pts with 3 mets (7/76, 7.4%) had decreased survival at 1, 2, and 3 years compared to pts with 1-2 (65/76, 85.5%) mets (p=0.6). 67 pts (70.5%) received mets-directed tx; RT alone was the most common modality (52/67, 77.6%), followed by surgery (6/67, 9%), RT plus surgery (5/67, 7.5%), and ablation alone (3/67, 4.5%). There was no significant difference in survival (HR 1.27, 95% CI (0.53, 3.07), p=0.589) or time to next tx (HR 0.95, 95% CI (0.56, 1.63), p=0.856) in pts who received mets-directed tx. Multivariate analysis was not performed because most findings were not statistically significant in univariate analysis. Conclusions We did not find any significant differences in survival based on characteristics like menopausal status or site or number of mets in pts with OMBC. There was a trend toward improved survival in pts with viscera-only mets, but this finding requires validation. Local/regional and mets-directed tx did not improve survival; however, survival at 1, 3, and 5 years was excellent in this OMBC pt population. Our study was limited by low pt numbers and heterogeneity in the pt population. Findings need validation in larger studies. Citation Format: Tanmayi Pai, Raza Zarrar, Zhongwei Peng, Zhuo Li, Lauren Cornell, Kostandinos Sideras, Rohit Rao, Alvaro Moreno-Aspitia, Saranya Chumsri, Sarah McLaughlin, James Jakub, Emmanuel gabriel, Sanjay Bagaria, Laura Vallow, Santo Maimone, Pooja Advani. Clinical Features and Survival Outcomes of Oligometastatic Breast Cancer Patients: The Mayo Clinic Experience [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 PO3-06-04.

Abstract PO1-16-11: Real-world features and outcomes of young advanced breast cancer (ABC) patients (pts) from RegistEM (GEICAM/2014-03) study

Abstract Background: BC is the most incident cancer worldwide in < 40 years old (y) women. Increasing body mass index and changes in reproductive history contribute to the growing incidence of premenopausal BC. A higher proportion of luminal B-like and estrogen receptor negative (ER─) tumors, an increased risk of early relapse, and more unfavorable longer-term outcomes for young women with ER+ tumors when compared to older women, have been reported. In this analysis, we focus on age-specific BC characterization from a real-world population-based perspective. Methods: Pts were enrolled in the non-interventional and ambispective RegistEM study in ABC diagnosed between 2016 and 2019. We describe the features and outcomes of < 50 y pts at their initial BC diagnosis according to their BC subtype. BC subtypes were based on the most recent tumor tissue sample (distant metastasis, and in its absence, primary BC). Comparisons between < 40 and ≥ 50 y groups were performed. Results: Pts < 50 y represent 39% (n=685) of total pts with available data (n=1739, any age group) in the registry. By age, 12% (n=212) were < 40y, and 27% (n=473) 40-49y. At first BC diagnosis, 75% and 25% pts had early BC (EBC) and de novo metastatic BC (MBC), respectively. In EBC pts, stage II (50%) and III (28%) were the most frequent at diagnosis; invasive non-special type carcinoma was the predominant morphology, and grade 2 was the most common histological grade, but grade 3 was predominant in TN pts and HER2+ < 40y pts. The median time to recurrence was < 2y in TN pts, 3y in HER2+ pts, and 6y in luminal HER2─ pts. At ABC diagnosis, the median age was 47y, all pts were female but one, 98% white, and 60% premenopausal (94% were premenopausal at EBC diagnosis). A family history of BC and/or ovarian cancer was reported in 34% pts, and a hereditary-risk genetic test was performed in 39% (254 of 652) pts; 12% (n=30) had BRCA1/2 mutations, with a proportion higher in TN pts (9 of 33, 27%) vs. luminal HER2─ (21 of 183, 12%) and HER2+ (0 of 38) pts. Visceral disease was the most frequent in all subgroups, highlighting statistical differences (p=0.022) between age groups ( < 40y 55% vs. ≥50y 71%) only in TN pts. 60% had ≤ 2 locations involved, similarly in all subgroups. The presence of >2 metastatic locations was statistically higher in HER2+ pts ≥50y (54%) vs both < 40y (32%) and 40-49y (48%). Brain disease was more present at ABC diagnosis in TN (9%) and HER2+ (7%) than in luminal HER2─ (3%). Median no. of treatment lines (L) was 3 (range 0-11), and median follow-up 44 mo (95% CI: 41-44). 99% pts received 1L, the distribution of treatments by BC subtype within each age subgroup was similar; median duration of 1L was 21 months (mo) in luminal HER2─, 17 mo in HER2+, and 5 mo in TN pts. 68% of pts who received 1L, reached 2L. Duration of 2L dropped dramatically: 8 mo in luminal HER2─, 6 mo in HER2+, and 2 mo in TN pts. No differences between ≥50y and the rest of pts were observed in PFS for any treatment line. 49% pts had died at the database cut-off date (05-April-23), with no differences between age groups, but TN pts had the highest death rate (80%). Additional data according to BC subtypes and age groups are in the table. Conclusions: Luminal HER2─ was the predominant BC subtype in all age subgroups. Visceral disease was more prevalent in young TN pts compared to older pts. TNBC pts experienced a shorter median time to recurrence and the highest mortality rate regardless of age, compared to HER2+ and luminal HER2- pts, indicating the need for targeted interventions in this subgroup. Citation Format: Sara López-Tarruella, Angel Guerrero, Isabel Álvarez, Silvia Antolin Novoa, Ariadna Tibau, Josefina Cruz, César A Rodríguez, Purificación Martínez, J. Ignacio Chacón, María Hernández, Mireia Margelí, Encarna Adrover, Catalina Falo, Iria González, Álvaro Rodríguez-Lescure, María Marín, César Gómez, Juan de la Haba-Rodríguez, J. José Illaramendi, Raquel Andrés, Andrea Blasco, Mª José Escudero, Susana Bezares, Federico Rojo. Real-world features and outcomes of young advanced breast cancer (ABC) patients (pts) from RegistEM (GEICAM/2014-03) study [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 PO1-16-11.

Abstract PO3-17-01: Brazilian Real-world data of HR+ HER2- early-stage Breast Cancer (BC) patients are poor when compared to control arms of recent adjuvant clinical trials

Abstract INTRODUCTION: In Brazil, BC is the most common neoplasm among women, with 73k new cases annually. Adjuvant hormone therapy (HT) options are evolving with personalized strategies based on risk stratification. Real-world data (RWD) plays a crucial role in understanding the outcomes in BC patients (pts) in low- and middle-income countries, where significant health disparities, access gaps, and barriers to the implementation of guidelines exist. This study aims to assess the epidemiologic profile, practice patterns, and real-world outcomes of pts with ER+ HER2- stage I-III BC treated in the largest network of private oncology services in Brazil and compare results with control arms of recent clinical trials evaluating CDK4/6 inhibitors in adjuvant setting. METHODS: Retrospective RWD study from Oncoclínicas Group with longitudinal EHR data from 2017 to 2022 merged in a platform where structured variables (demographics, tumor staging, pharmacy records) are integrated with unstructured data from physician notes and digitized pathology-molecular reports using technology-based abstraction performed by expert human curators that follow mCODE standards and predefined ontology. Treatment patterns and invasive disease-free survival (IDFS) outcomes were collected. Regarding risk stratification, pts were classified as high-risk (HR) if: (i) 4+ axillary lymph nodes (LN), or (ii) 1-3 LN and grade 3 and/or Ki620% and/or high-risk ODX/Mammaprint; intermediate-risk (IR) if: (iii) 1-3 LN with grade 1-2 and/or Ki67 < 20% and/or non-high-risk ODX/Mammaprint, or (iv) N0 with grade 2-3 and/or Ki67 >20% and/or high-risk ODX/Mammaprint; and low-risk (LR) if: (v) all other stages I and IIA not having the risk factors above. RESULTS: From over 30k BC pts in Oncoclínicas Database, 19k had HR+/HER2- early BC, 12k were treated in high-volume clinics, and 1,786 cases were selected for the study (diagnosis and first treatment in the last 6 years, complete histopathology and pharmacy registries). The median age was 57 years (27-96), 566 (32%) pts were premenopausal, 1052 (59%) had stage I disease, 372 (21%) stage IIA, 165 (9%) stage IIB and 197 (11%) stage III BC. Regarding risk stratification, 1,179 (66%) were LR, 351 (20%) IR, and 256 (14%) HR. In post-menopausal pts, aromatase inhibitor (AI) was used by 74% of pts with LR, 79% with IR and 83% with HR. In premenopausal pts, ovarian function suppression (OFS) – combined with tamoxifen or AI – was prescribed to 18% of LR pts, 15% of IR pts, and 48% of HR pts. Chemotherapy (CT) was offered to 32%, 38%, and 73% of postmenopausal pts in LR, IR, and HR groups. In premenopausal pts, 55%, 57%, and 78% received CT in LR, IR, and HR groups. The 3-year iDFS in the general population was 85%, reaching 80% in premenopausal and 86% in postmenopausal pts. The overall 3y iDFS was 87% in the LR, 86% in IR, and 72% in HR. Among premenopausal pts, the 3y iDFS was 81% in LR, 92% in IR, and 64% in the HR group. While the risk distribution of our cohort is similar to recent clinical trials, the 3y iDFS outcomes were numerically lower to those observed in the control groups of the pivotal trials evaluating adjuvant CDK4/6 inhibitors. In the HR group, the 3y iDFS was 72% (versus 84% 3y iDFS in the control arm of the MonarchE trial). Combining the IR/HR groups, the 3y iDFS was 80% (versus 87% in the control arm of NATALEE trial). CONCLUSION: In this large RWD cohort treated in a private setting in Brazil, most pts are diagnosed with stage I and LR BC. In this cohort, a significant proportion of premenopausal pts with IR/HR are not treated with OFS and do not receive CT. Real-world survival outcomes of Brazilian women with HR+ HER2- early BC treated in private clinic are inferior to those observed in recent clinical trials, especially in the premenopausal pts. In public healthcare system, where prevalence of HR disease is higher and access to essential treatments more limited, outcomes might even be worsened compared to the ones presented here. Citation Format: Aline Goncalves, Tomas Reinert, Max S. Mano, Heloisa Cruz, Cristiano Resende, Gustavo Bretas, Carlos Barrios, Matheus Costa e Silva, Rafael Paes, Guilherme Silva, Erika Martins, Fernanda Koyama, Bruno Ferrari, Carlos Gil Ferreira, Pedro Aguiar Junior, Rodrigo Dienstmann. Brazilian Real-world data of HR+ HER2- early-stage Breast Cancer (BC) patients are poor when compared to control arms of recent adjuvant clinical trials [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 PO3-17-01.

Deciphering the role of apoptosis signature on the immune dynamics and therapeutic prognosis in breast cancer: Implication for immunotherapy

Background: In breast cancer oncogenesis, the precise role of cell apoptosis holds untapped potential for prognostic and therapeutic insights. Thus, it is important to develop a model predicated for breast cancer patients’ prognosis and immunotherapy response based on apoptosis-related signature.Methods: Our approach involved leveraging a training dataset from The Cancer Genome Atlas (TCGA) to construct an apoptosis-related gene prognostic model. The model’s validity was then tested across several cohorts, including METABRIC, Sun Yat-sen Memorial Hospital Sun Yat-sen University (SYSMH), and IMvigor210, to ensure its applicability and robustness across different patient demographics and treatment scenarios. Furthermore, we utilized Quantitative Polymerase Chain Reaction (qPCR) analysis to explore the expression patterns of these model genes in breast cancer cell lines compared to immortalized mammary epithelial cell lines, aiming to confirm their differential expression and underline their significance in the context of breast cancer.Results: Through the development and validation of our prognostic model based on seven apoptosis-related genes, we have demonstrated its substantial predictive power for the survival outcomes of breast cancer patients. The model effectively stratified patients into high and low-risk categories, with high-risk patients showing significantly poorer overall survival in the training cohort and across all validation cohorts. Importantly, qPCR analysis confirmed that the genes constituting our model indeed exhibit differential expression in breast cancer cell lines when contrasted with immortalized mammary epithelial cell lines.Conclusion: Our study establishes a groundbreaking prognostic model using apoptosis-related genes to enhance the precision of breast cancer prognosis and treatment, particularly in predicting immunotherapy response.

Abstract PO5-27-10: Next generation antibody drug conjugates: Multi-payload conjugates targeting multiple mechanisms of cell killing

Abstract Background: ADCs have had tremendous impact on patient outcomes in breast cancer and are rapidly moving towards second line use. However, many patients fail to respond or relapse after treatment with ADC therapies due to tumor heterogeneity and resistance to ADC payloads. Method: CatenaBio has developed a novel Multi-Payload-Conjugate (MPC) system capable of attaching distinct payloads at different sites to the same antibody, enabling the production of single-molecule targeted combination therapies with defined DAR. Results: We screened combinations of different payloads targeting several different mechanisms attached to trastuzumab at different drug-antibody ratios to optimize tumor cell killing. These targeted combination ADCs demonstrated robust killing in both HER2 high and low tumor cell lines. Conclusion: Antibody Drug Conjugates have revolutionized the treatment of high HER2 positive breast cancer. More recently advances have been made in the design of ADCs to expand indications to include HER2 low as well as HER2 negative patients. These constructs offer the next step in ADC design and allow for the combination of multiple mechanisms of action in a single MPC that are highly effective across multiple breast cancer cell lines. These molecules offer the potential to circumvent tumor resistance pathways and deliver deeper and more durable responses. Disclosures: Marco Lobba, Devin Trinter, Maxwell Nguyen, Daniel Gutierrez, Samantha Brady, Chanez Symister, Andrew Lau, Richard Kendall, and Saurabh Johri are employed by Catena Biosciences. Matthew Francis is a co-founder and advisor to Catena Biosciences. Citation Format: Marco Lobba, Devin Trinter, Maxwell Nguyen, Daniel Gutierrez, Samantha Brady, Chanez Symister, Andrew Lau, Richard Kendall, Saurabh Johri, Matthew Francis. Next generation antibody drug conjugates: Multi-payload conjugates targeting multiple mechanisms of cell killing [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 PO5-27-10.

Abstract PO1-25-03: Programmed Death-Ligand 1 and Receptor Tyrosine Kinases in Breast Cancer

Abstract Programmed death-ligand 1 (PD-L1) is an immune checkpoint expressed in a wide range of malignancies leading to immune tolerance and cancer cell immune evasion. Receptor tyrosine kinases (RTKs) are key regulators of cancer cell proliferation, survival, and invasion. The Hepatocyte Growth Factor (HGF) receptor, MET, and the Epidermal Growth Factor Receptor (EGFR) are RTKs known for their tumorigenic potential in a variety of human malignancies. This study aimed to evaluate the effect of the small-molecule tyrosine kinase inhibitors (TKIs) on the expression of PD-L1 in breast cancer cells and the effect of their combination with inflammatory cytokines. The study also assessed the association of the expression of the tumoral PD-L1 mRNA with each of MET and EGFR mRNA expression and the tumor features and treatment outcomes in breast cancer patients using the METABRIC dataset publicly available from cBioPortal for Cancer Genomics. The TKIs crizotinib [a MET inhibitor] and gefitinib [an EGFR inhibitor] were used as a single treatment and in combination with the cytokines; tumor necrosis factor-α (TNF-α) or interferon-γ (INF-γ) in MCF7 and MDA-MB-231 breast cancer cells in vitro. The cells were also treated with the mitogens HGF and EGF. The viability of cells after the different treatments was determined using the MTT viability assay. The effects of the combination treatments were analyzed using combination index (CI) analysis. The expression level of PD-L1 in cancer cells was assessed using Western blotting. The combination treatment of crizotinib with TNF-α and INF-γ produced a synergistic growth inhibition of MCF7 and MDA-MB-231 cells with CI values of 0.31 and 0.55, respectively. Alternatively, combined crizotinib and TNF-α produced an antagonist effect on the viability of MCF7 cells (CI=2.49). The combination of gefitinib with TNF-α produced a synergistic growth inhibition in both MCF7 and MDA-MB-231 cells with CI values of 0.39 and 0.78, respectively. Alternatively, gefitinib resulted in an additive effect when combined with INF-γ (CI=0.99) and an antagonistic effect when combined with TNF-α (CI=2.68) in MCF7 and MDA-MB-231 cells, respectively. Treatment with HGF (50 and 100 ng/ml) increased the protein levels of PD-L1 while EGF (50 and 100 ng/ml) reduced its levels in MDA-MB-231 cells. Treatment with the TKIs crizotinib (0.1-4 µM) and gefitinib (1-40 µM) significantly reduced PD-L1 levels in MDA-MB-231 cells compared to vehicle-treated cells. The analysis of the METABRIC dataset revealed that the mRNA expression of PD-L1 was positively correlated with the mRNA expression of the EGFR gene (r= 0.081, p< 0.001) but not the MET gene. A double-high PD-L1/MET expression was significantly associated with younger age at diagnosis, high-grade carcinoma, greater tumor size, hormone receptor-negative status, HER2-positivity, and non-luminal disease compared to patients with a double-low PD-L1/MET expression. Similar findings were reported for patients with a double-high PD-L1/EGFR expression compared to patients with a double-low PD-L1/EGFR expression. Nevertheless, the mRNA expression of the PD-L1, MET, and EGFR genes as well as the co-expression of PD-L1/MET or PD-L1/EGFR genes did not affect the overall survival of breast cancer patients. Collectively, MET and EGFR TKIs could modulate the effects of inflammatory cytokines differently based on the type of cytokine and the molecular subtype of breast cancer cells. The expression of PD-L1 in breast cancer cells was upregulated by HGF while TKIs reduced its expression. The co-expression of the PD-L1 gene with MET and EGFR genes in breast cancer was associated with advanced disease presentation and worse prognosticators in patients. Together, TKIs that target MET or EGFR could be an appealing therapeutic target in breast cancer, particularly in younger patients with the non-luminal disease. Citation Format: Nehad Ayoub, Muhsen Al-Diabat, Moath Al-Shorman, Laith Al-Eitan. Programmed Death-Ligand 1 and Receptor Tyrosine Kinases 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 PO1-25-03.

Survival After Contralateral Axillary Metastasis in Breast Cancer.

Despite stage IV categorization, survival outcomes for breast cancer patients who experience contralateral axillary lymph node metastasis (CAM) remain uncertain. This study aimed to investigate the clinical outcomes for patients with metachronous CAM to provide insights into its prognosis and treatment recommendations. This study retrospectively reviewed medical records of patients who underwent curative surgery for breast cancer and experienced CAM as the first site of distant metastasis (DM) during the follow-up period between January 2001 and April 2023. Survival outcomes of the CAM patients were compared with those of breast cancer patients with other DM via propensity score-matching (PSM). The study identified 40 breast cancer patients with metachronous CAM. The estimated 5-year overall survival (OS) was 39.6%, and the progression-free survival was 39.4%. The patients with CAM exhibited marginally better OS than the patients with DM (p = 0.071), but survival similar to that of the patients with isolated supraclavicular node recurrence (SCN) (p = 0.509). Moreover, matching of CAM with DM using two PSM models showed a consistently insignificant survival difference (hazard ratio [HR], 1.47; p = 0.124 vs. HR, 1.19; p = 0.542). Ipsilateral breast tumor recurrences (IBTRs) were experienced by 12 patients before or concurrently with the CAM. These patients exhibited significantly better survival than the remaining patients (HR, 0.28; p = 0.024). The breast cancer patients with CAM showed survival similar to that for the patients with DM, supporting the current stage IV classification of the CAM. However, CAM associated with IBTR exhibited superior survival outcomes, suggesting that this subset of CAM may benefit from treatments with curative intent.

Abstract PO4-22-03: Intensity Modulated Proton Therapy (IMPT) for the Definitive Adjuvant Management of Women with Breast Cancer: A Single Institutional Experience of 5-Year Oncologic Outcomes

Abstract Purpose: There is limited data reporting the oncologic outcomes of breast cancer patients treated definitively with adjuvant proton beam therapy. Here we report a single institutional experience of oncologic outcomes, treating a predominantly vulnerable breast cancer patient population and compare these to historical standards primarily utilizing photon therapy. Materials and Methods: Unver IRB approval, we retrospectively reviewed 453 definitively treated breast cancer patients from 2016 – 2023 using adjuvant IMPT as part of their cancer care. Patients with recurrent disease, receiving re-irradiation, and those with less than 1-year of follow up were excluded from this analysis. Patients were treated with surgery and systemic therapies as per standards of care. Radiation therapy was administered using pencil beam scanning IMPT with daily image guidance. χ2 and Mann-Whitney U tests were performed to determine differences between select variables. Kaplan-Meier analysis and Cox proportional hazard models were used to analyze overall survival (OS). Results: With a median follow up of 22 months for the entire cohort, 453 patients were treated at XXXX as part of definitive adjuvant management for their breast cancer. Nearly 30% of patients self-identified as black (n=135), average patient age was 54 and 56% (n=255) self-identified as being married with approximately 25% (n=109) of patients having Medicare/Medicaid insurance. 198 patients (43.8%) had an intact breast and the remainder mastectomy of which 37.4% had reconstruction at the time of their radiation. 229 patients (50.7%) received neoadjuvant chemotherapy while 55 patients (12%) received concurrent chemotherapy which was either her2+ directed or Xeloda. The number of patients (%) corresponding to the AJCC 8th edition anatomical staging is as follows: Stage 0: 12 (2.7%); Stage I: 91 (20.1%); Stage 2: 197 (43.6%); Stage 3: 152 (33.6%). Median RT dose delivered for patients receiving comprehensive treatment was 50.4 Gy with 81% of patients receiving a boost to either scar, lumpectomy cavity and/or LN regions. Median RT dose delivered for patients receiving whole breast radiation was 42.56 Gy with a 10 Gy lumpectomy cavity boost. 5-yr OS by stage was 0: 100%; stage I: 98.8%; stage 2: 93.5%; stage 3: 90.8%. Five-year OS for black, white and other race patients were 85.3%, 95.8% and 96%, respectively (White as Ref: HR 3.176, 95% CI: 1.313-7.681, p=0.010 for black patients). For the entire cohort, patients with triple negative disease had a 5-yr OS of 80.4% (HR: 4.33, 95% CI 1.87-10.04, p< 0.001) and there was no difference in OS when insurance status was considered (p=0.378). Conclusions: To the best of our knowledge this represents the largest series of definitively treated breast cancer patients utilizing adjuvant proton therapy and the 5-year OS rates in our analysis coincide with published standards1. Results from the on-going randomized RADCOMP study will provide further guidance as to which patients benefit the most from proton therapy and will further support equivalent oncological outcomes when compared to photon therapy. 1. Weiss A, Chavez-MacGregor M, Lichtensztajn DY, et al. Validation study of the American Joint Committee on Cancer eighth edition prognostic stage compared with the anatomic stage in breast cancer. JAMA Oncol. 4(2):203-209, 2018. Citation Format: Elizabeth Nichols, Gurbani Singh, Desiree Lejano, Sarah McAvoy, Mark Mishra, Melissa Vyfhuis. Intensity Modulated Proton Therapy (IMPT) for the Definitive Adjuvant Management of Women with Breast Cancer: A Single Institutional Experience of 5-Year Oncologic Outcomes [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 PO4-22-03.

Abstract PO3-15-10: Enhanced Cancer Cell Proliferation and Aggressive Phenotype Counterbalance in Breast Cancer with High BRCA1 Gene Expression

Abstract Introduction: It is estimated that 5–10% of all breast cancer cases have a hereditary component with BRCA1 mutation being one of the most frequently observed gene mutations in breast cancer patients. BRCA1 plays a crucial role in DNA repair, and its mutation has been extensively studied. However, the clinical significance of BRCA1 gene expression remains largely unexplored. Given that heightened DNA repair mechanisms can potentially increase cancer cell proliferation, we hypothesized that breast cancer with high BRCA1 gene expression might be associated with aggressive tumor biology and worse survival. Methods: The clinical, pathological and gene expression levels of a total of 6,245 breast cancer patients were analyzed from three large independent cohorts: METABRIC (n = 1,903), GSE96058 (n = 3,273), and The Cancer Genome Atlas (TCGA, n = 1,069). The data was retrieved through cBioPortal. The xCell algorithm was used to correlate the BRCA1 gene expression with the stromal and immune cell fractions infiltrating the tumor microenvironment (TME). Results: BRCA1 gene expression was higher in breast cancer patients without BRCA1 mutation, and it correlated with the DNA repair activity (p = 0.026 and p < 0.01 respectively), however, it did not correlate with BRCA2 gene expression (p = 0.38). Breast cancer with high BRCA1 gene expression was associated with cancer cell proliferation as evidenced by higher Nottingham histological grade (p < 0.001), Ki67 expression (p < 0.001), significant enrichment of cell proliferation-related gene sets such as E2F Targets, G2M Checkpoint, MYC Targets V1 and V2, Mitotic Spindle (all FDR < 0.25), and significantly less infiltration of stromal cells such as adipocytes, fibroblasts, microvascular and lymphatic endothelial cells, and pericytes (all p < 0.05). High BRCA1 gene expression was associated with higher homologous recombination deficiency, intratumor genomic heterogeneity, and fraction altered (all p < 0.001); however, there was no correlation observed with mutation rates or neoantigens. It was observed that breast cancer with high BRCA1 gene expression had less infiltration of CD8 T cells, dendritic cells, regulatory T cells, and B cells and had higher infiltration of Th1 cells (all p < 0.05). To our surprise, there was no significant difference in overall survival regardless of the subtypes (except for ER+/HER2- subtype in METABRIC cohort, p = 0.03). Breast cancer with low BRCA1 gene expression enriched cancer aggravating pathway gene sets such as Cancer Stem Cell-related signaling pathways (NOTCH and HEDGEHOG), Angiogenesis, Epithelial Mesenchymal Transition, Inflammatory Response, and TGF-beta signaling (all FDR < 0.25). Conclusion: Contrary to our initial hypothesis, we did not find any significant association between BRCA1 gene expression and survival outcomes in breast cancer patients. Based on the results of our study, we speculate that the interplay between enhanced cancer cell proliferation and aggressive tumor characteristics may counterbalance the effect of high BRCA1 expression in breast cancer. Citation Format: Kohei Chida, Masanori Oshi, Arya Mariam Roy, Itaru Endo, Kazuaki Takabe. Enhanced Cancer Cell Proliferation and Aggressive Phenotype Counterbalance in Breast Cancer with High BRCA1 Gene Expression [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 PO3-15-10.