Negative Breast Cancer Patients Research Articles

Is Axillary Lymphadenectomy Necessary in Triple Negative Breast Cancer Patients Treated with Subcutaneous Mastectomy with The Immediate Reconstruction?

Is Axillary Lymphadenectomy Necessary in Triple Negative Breast Cancer Patients Treated with Subcutaneous Mastectomy with The Immediate Reconstruction?

Abstract PO5-14-02: Diagnostic leukapheresis to increase CTC detection rate in breast cancer patients after 5 years of adjuvant endocrine treatment

Abstract Purpose: Patients with early hormone receptor positive, HER2 negative breast cancer have a risk of recurrence for up to 20 years after the initial diagnosis and is therefore treated with adjuvant endocrine treatment (ET) for 5 to 10 years. As a result there is a large proportion of patients that overtreated, hence, an urgent need for better biomarkers to guide treatment decisions. In previous research, it was shown that circulating tumor cells (CTCs) are detected in 5% of patient after 5 years of adjuvant treatment and that this indicated a 13-fold higher risk of recurrence, with a median lead time of 2.8 years. However, the sensitivity and specificity of the test were moderate. This could be caused by stochastic variation, given the low numbers of CTCs detected in 7.5 ml peripheral blood. We hypothesized that increasing the screening volume, increases the test statistics. Methods: In this study, we investigated whether increasing the screening volume by diagnostic leukapheresis (DLA) can increase the detection rate of CTCs (CellSearch platform). With DLA, 5 liters of peripheral blood was screened, which in previous studies had shown to increase the CTC-yield per ml by 25-fold. To this end, we included early hormone receptor positive, HER2 negative breast cancer patients that were treated with ET for 4.5-5.5 years with no signs of disease recurrence. We compared the number of detected CTCs in the standard fraction of 7,5 mL peripheral blood (PB), to buffy coat (30 ml), to DLA sample (200 × 109 white blood cells (WBC), equal to 25-50 mL PB) and to DLA after WBC depletion. Results: Thirty two hormone receptor positive/HER2 negative breast cancer patients were included in this study after a median duration of ET of 60 months, of which 3 (9%) patients completed ET according to clinical guidelines and the remaining patients were still on treatment. Twenty eight patients (88%) had 1-3 positive lymph nodes at diagnosis, and 3 patients had 4-9 positive lymph nodes. The Clinical Treatment Score at 5 years (CTS5 score) was intermediate or high in 75%, and unknown in 19%, indicating a recurrence risk of >5% at years 5-10 after diagnosis. In none of the included patients, CTCs were detected in 7,5 ml PB, nor in any of the other tested blood volumes. To date, 2 patients have been diagnosed with overt metastatic disease during follow-up. DLA was well tolerated and did not cause adverse events. Conclusions: We conclude that DLA was unable to increase the detection rate of CTCs in hormone receptor positive, HER2 negative patients with early breast cancer being on treatment for a median duration of 5 years. Additional circulating tumor DNA analyses are planned. Citation Format: Noortje Verschoor, Jaco Kraan, Johanna Zuetenhorst, Mijntje Vastbinder, Jan Drooger, Stefan Sleijfer, Saskia M Wilting, John WM Martens, Agnes Jager. Diagnostic leukapheresis to increase CTC detection rate in breast cancer patients after 5 years of adjuvant endocrine treatment [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 PO5-14-02.

Abstract PO4-19-10: Selective Avoidance of Sentinel Lymph Node Biopsy After Neoadjuvant Chemotherapy In HER-2 Positive/Triple Negative Breast Cancer Patients With Excellent Radiologic Response to the Breast and Axilla

Abstract Background Neoadjuvant chemotherapy (NACT) for breast cancer (BC) is downstaging inoperable tumors into operable tumors and de-escalating breast/axillary surgery. According to advanced NACT, dual human epidermal growth factor-2 (HER2) blockage in HER2-positive BC, carboplatin, and immunotherapy in triple-negative breast cancer (TNBC) revealed pathologic complete response (ypCR) rates of up to 68% and 80%, the indications for NACT have expanded to early BC and the expected ypCR rate has increased. Therefore, it may be reasonable to consider omitting surgery in cases with excellent responses to NACT. Although sentinel lymph node biopsy (SLNB) is minimally invasive, some patients still experience complications such as lymphedema, pain, sensory loss, and axillary web syndrome. Several recent retrospective studies and pilot prospective studies have reported axillary pathologic complete response (ApCR) is highly correlated with breast pathologic complete response (BpCR). In cN0 with HER2+ BC and TNBC, the ApCR rate in BpCR after NACT was reported up to 100%, and in cN1 with HER2+ BC and TNBC, the ApCR rate in BpCR after NACT was reported about 85%. There are many studies predicting BpCR using radiologic imaging such as breast mammography (MMG), ultrasonography (USG), and magnetic resonance imaging (MRI). However, the combination of tri-modality (MMG, USG, MRI) could not confirm BpCR. The current study is screened in cT1-3N0-1M0, HER2+ or TNBC, and planned breast-conserving surgery (BCS) patients after NACT with excellent response at the combination of tri-modality imaging (breast MMG, breast USG, breast MRI) and with expected BpCR at physical examination. Methods Trial design The ASLAN trial is a prospective, multicenter, single-arm, clinical study. The five tertiary care hospitals in South Korea are participating which are members of the Korean Breast Cancer Study Group (KBCSG). Eligibility Inclusion criteria: women aged 20-69; cT1-3N0-1M0; HER2+ or TNBC (defined by ER-negative (< 10% positive cells in IHC) and PR-negative (< 10% positive cells in IHC)); expected complete remission at physical examination and radiological expected Tumor size ≤ 2cm or non-mass enhancement ≤ 4cm at breast MRI after standard NACT; planned breast-conserving surgery (BCS) with whole-breast irradiation; ECOG performance status 0-1. Exclusion criteria: SLNB before NACT; previous axillary surgery; bilateral BC; pregnancy. Intervention In eligible patients, BCS was performed. After BCS, patients who showed BpCR are enrolled with the omission of SLNB. Patients with no BpCR proceed with routine axillary surgery. Sample size calculation The assumption for an acceptable 5-year RFS ≥84% is based on previous study findings. The calculated total case number for per-protocol analysis is N=178. By Jun 2023, 153 patients had been enrolled and the target accrual of 178 patients is expected to be complete by Dec 2023. Study outcomes Primary endpoint: 5-year recurrence-free survival. Secondary endpoint: local recurrence-free survival, breast cancer-specific survival, overall survival, ipsilateral axillary recurrence interval, distant metastasis-free survival, contralateral breast-free survival, re-operation rate according to breast biopsy after NACT, adverse event, and quality of life. Accrual Plans The first patient was enrolled on Sep 2021. Among 223 patients who were screened, 153 patients have been enrolled in Jun 2023. We plan to complete the target accrual by Dec 2023. Conclusion The primary aim of the ASLAN trial is to demonstrate the oncologic safety of omitting axillary surgery for the excellent response after NACT in HER2+ or TNBC, early breast cancer patients undergoing BCS and adjuvant RT ASLAN trial, altogether with the EUBREAST-01 and ASCIS trials, will answer the very important question that may alter the axillary surgery in highly selected patients after NACT Citation Format: Jai Min Ryu, Wonshik Han, Han-Byoel Lee, Sung Gwe Ahn, Hee Jeong Kim, Hyung Seok Park, Ji Soo Choi, Hyunjun Lee, Hae Young Kim, Jeong Eon Lee. Selective Avoidance of Sentinel Lymph Node Biopsy After Neoadjuvant Chemotherapy In HER-2 Positive/Triple Negative Breast Cancer Patients With Excellent Radiologic Response to the Breast and Axilla [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 PO4-19-10.

Abstract PO1-14-02: Real world application of a 21-gene recurrence score in a Swiss single center breast cancer population. A comparative analysis of treatment administration before and after TAILORx

Abstract TAILORx was published in July 2018 and showed benefit of chemotherapy (CHT) in premenopausal, HER2 negative breast cancer (BC) patients with a 21-gene intermediate recurrence score (RS). The aim of this study was to determine treatment patterns before and after publication of TAILORx at our Swiss BC center. This is a retrospective analysis of 326 estrogen receptor positive (ER+)/HER2 negative BC patients, treated at Basel University Hospital and Cantonal Hospital Baselland from 2010-2021. Primary endpoint was to assess change in therapy before (cohort A) and after the publication of TAILORx (cohort B) when adjusted for RS category thresholds as defined by the manufacturer and as modified in the TAILORx study protocol. Secondary endpoint was to determine main therapy decision factors. There were no significant differences in the two populations. A included 165 and B 161 patients with a mean RS of 17.72 and 17.89 (p=0.87) respectively. No differences were noted in terms of demographics or tumor characteristics between the two groups. Mean age in A was 58.8 and in B 57.7 years old. There was a tendency for higher ASA scores in B (p=0.262) and higher BMIs in A (p=0.612). There were no differences in RS distribution between A and B when adjusted to manufacturer’s thresholds (p=0.15 for low RS, 0.833 for intermediate and 0.15 for high RS), and subsequently to TAILORx thresholds for RS categories (p=0.817 for low RS, 0.199 for intermediate and 0.795 for high RS). There was no difference in the 2 populations with regards to number of positive nodes (p=0.366) and pN status (p=0.903). In the intermediate node negative population, there were 67 patients in A and 55 in B. No significant differences were noted in demographics (median age 58.9 years in A and 57.2 years in B, p=0.414, menopausal status, p=0.806, relevant comorbidities in 28 patients in A and 21 in B, p=0.864). A relevant tendency for higher ASA scores in B was maintained in this subgroup, with a median score of 3 in B vs 2 in A, p=0.001). Mean tumor size was 20.73 mm in A and 21.17 mm in B (p=0.857) with a mean Ki67 of 20% in both A and B and more cases of higher Ki67 in B (40%) vs A (22%) but not significant (p=0.624). Mean RS was 17.43 in A and 17.75 in B (p=0.674). In the intermediate nodal negative subgroup, the majority had conservative breast surgery (64% in A and B), with less reconstruction in A vs B (46% vs 52%, p=0.031). Radiotherapy (RT) was administered in 66% of women in A and 69% in B (p=0.307) with a mean dose of 53.41 Gy in A and 50.75 Gy in B (p=0.153). Only 4 patients had CHT in A and one patient in B (p=0.775) with one case of severe CHT associated complications in A. Seven patients refuse CHT. In A 31% of patients and in B 44% had osteo-oncologic treatment (p=0.005). There are 7 cases of relapse in A and 3 in B (p=0.492) with one BC related death in A. Tumor board seems to weight more post TAILORx (82% of decision implementation in B vs 63% in A, p=0.38). In the whole population, RS influences decision in the low category, with 91% alignment of RS recommended treatment in A. In B there seem to be a tendency toward more hormonal therapy (138%) but no reduction in CHT application, while in A more patients were administered CHT than recommended by RS guidelines (181%, p< 0.001). Therapy decision is not influenced by demographic nor tumor characteristics in A nor B, and there are no differences in surgery (68.4% in A and 64% in B, p=0.352), endocrine therapy (65.4% in A vs. 52% in p=0.113), RT (78% in A and 76% in B, p=0.223). At a median follow up of 62.9 months in A and 19.5 in B, relapse was higher in A (19) vs B (5) (p< 0.001) with 5 deaths in A vs none in B. However due to study design which implies different dates of inclusion in the analysis, as well as limited number of events, this data has no power. Before TAILORx decision was mainly dependent on tumor features. After TAILORx other factors, which are particular to every case weight more. This data shows that therapy decisions are not particularly shifted after TAILORx, confirming the emergence of personalised medicine. Demographics, Tumor Characteristics, Therapy and Outcome, RS Categories Thresholds in two Cohorts before and after Publication of TAILORx. What changed? Citation Format: Elena D Chiru, Cvetka Grasic Kuhar, Christian Kurzeder, Marcus Vetter. Real world application of a 21-gene recurrence score in a Swiss single center breast cancer population. A comparative analysis of treatment administration before and after TAILORx [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 PO1-14-02.

Abstract PO4-20-03: HIPEx: Adjuvant palbociclib plus endocrine therapy in ER-positive HER2-negative early breast cancer with high recurrence score according to GenesWellTM BCT; a multi-center single arm phase II clinical trial (KCSG BR 19-13)

Abstract Background: In estrogen receptor (ER)-positive human epidermal growth factor receptor2 (HER2)-negative early breast cancer (EBC) patients, NCCN treatment guideline recommend 21-gene tests for decision of adjuvant chemotherapy if tumor size is over 0.5cm or node positive disease. In addition, GenesWellTM BCT is a prognostic assay that predict the risk of recurrence in patients with ER-positive HER2-negative and nodal stage 0-1 EBC. According to gene tests, EBC patients with high recurrence risk would have help from adjuvant chemotherapy to increase the rate of disease free survival but toxicities of chemotherapy are not negligible. Therefore, the effort for escaping adjuvant chemotherapy has been performed and currently CDK4/6 inhibitor would be considered as the substitute for cytotoxic chemotherapy in ER-positive HER2-negative EBC patients. Methods: HIPEx trial is a multi-center, phase II clinical trial to determine the efficacy of adjuvant palbociclib plus endocrine therapy in ER-positive HER2-negative EBC with high recurrence score according to GenesWellTM BCT (NCT04247633). Eligible patients are women who received curative surgery and diagnosed as ER-positive, HER2-negative and pathologic stage T1b-T2 and/or N0-1. Clinical recurrence risk is high according to the modified Adjuvant! Online guideline and GenesWellTM BCT score is 4 or more which being genomic high risk. Other criteria include ECOG performance status ≤1, adequate organ functions and availability of an archival surgical specimens. Patients receive palbociclib 125mg once daily for 21 days of 28-day cycle plus tamoxifen or aromatase inhibitor (anastrozole, letrozole or exemestane) once daily for every day. Palbociclib would be taken for two years and endocrine therapy for five years or more. If adjuvant radiotherapy is required, palbociclib should be taken two weeks after the end date of radiotherapy. If patients are premenopausal status, GnRH agonist is allowed. Primary endpoint is 3-year event free survival (EFS) rate of high clinical and genetic risk ER-positive EBC. Secondary endpoints include 3-year overall survival, quality of life, safety and tolerability of palbociclib with endocrine therapy as an adjuvant setting, exploratory analysis of predictive and prognostic biomarkers and the performance of GenesWellTM BCT for 3-year EFS rate. In total, 578 patients would be enrolled in this trial. Based on the previous results of GenesWell™ BCT in Korea, the 3-year EFS rate for the past control group (chemotherapy followed by endocrine therapy) is 87.0% and the treatment group in this clinical trial is assumed to be 90.5%.(hazard ratio for EFS = 0.717). Null hypothesis is the 3year-EFS rate in patients received adjuvant palbociclib and endocrine therapy is not less than that of the past control group. Alternative hypothesis is the 3year-EFS rate of this trial is less than that of the past control group (one-sided). Significance level is 0.025, power is 0.80. Considering 10% drop out rate, 4-years of accrual patient enrollment and 3-years of follow up period, 578 patients were required in this clinical trial. Citation Format: Ji-Yeon Kim, Sung Hoon Sim, Jieun Lee, In Hae Park, Kyong Hwa Park, Seock-Ah Im, Jee Hung Kim, Kyoung Eun Lee, Jeong Eon Lee, Jai Min Ryu, Young Kee Shin, Yeon Hee Park. HIPEx: Adjuvant palbociclib plus endocrine therapy in ER-positive HER2-negative early breast cancer with high recurrence score according to GenesWellTM BCT; a multi-center single arm phase II clinical trial (KCSG BR 19-13) [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 PO4-20-03.

Abstract PO2-02-03: Clinical and pathological factors associated with Oncotype DX® 21-Gene recurrence score in patients diagnosed with early stage breast cancer in a low-middle income country

Abstract INTRODUCTION: Oncotype DX® recurrence score (ODX RS) is a 21-gene assay warranted to determine the the prognosis in patients with hormone receptor positive, HER-2 negative early stage breast cancer. In this context, the test is also predictive of benefit of adjuvant chemotherapy.1,2,3 OBJECTIVES: We aimed to correlate the clinical and pathological factors associated with Oncotype DX® 21-Gene in patients diagnosed with early stage Breast Cancer. Additionally, description of adjuvant treatment patterns and survival outcomes were described according to the Oncotype DX® 21-Gene result. METHODS: Data from medical records from a single center in Brazil were collected retrospectively from women over 18 years diagnosed with early breast cancer between 2012 and 2022. Included patients were diagnosed with stage T1-T2 breast cancer, hormone receptor positive, HER-2 negative, with up to three positive lymph nodes. All included patients had an Oncotype DX® test performed after definitive breast surgery. The ODX RS has been categorized into two levels according to menopausal status. Correlation between breast cancer recurrence and clinicopathological characteristics was done. The software SPSS was used for statistical analyzes with the significance of 0.05. RESULTS: From 197 patients, 20 have had breast cancer recurrence (10.15%) whom 10 were premenopausal and 10 were postmenopausal. The median ODX RS in these 20 patients was 15 (ranged from 9 to 31). The most common site of recurrence was breast and regional recurrence in 18 patients (90%). Adjuvant chemotherapy was omitted in 16 patients (80%) who have had breast cancer recurrence. Among premenopausal patients whose ODX RS was >20, 33 patients (91.66%) received adjuvant chemotherapy. Among postmenopausal patients whose ODX RS was >25, 19 (86.36%) received adjuvant chemotherapy. The probability of recurrence free survival was worse in premenopausal patients > 44-years-old compared to those with < =44 years-old (p = 0.036) and also worse in histological grade 3 tumors compared to grade 1 (p=0.0048). Tumor size >14 millimeters (mm) was correlated to worse recurrence free survival in premenopausal patients (p=0.017). Low estrogen and progesterone receptor was associated with a higher ODX RS (p=0.0035 and p< 0.0001, respectively) in premenopausal patients, but not associated with recurrence free survival. Clinicopathological characteristics and recurrence free survival correlation in postmenopausal patients were not significant. CONCLUSION: This retrospective analysis suggests that factors other than the Oncotype DX® score, such as age and grade contributed to worse survival outcomes among our patients population. Of note, age older than 44 years-old, histological grade 3 and tumor size >14 mm were associated with a higher probability of recurrence in premenopausal patients, despite the Oncotype DX® score. REFERENCES: 1. Paik S, Shak S, Tang G, Kim C, Baker J, Cronin M, et al. A multigene assay to predict recurrence of tamoxifen-treated, node-negative breast cancer. N Engl J Med [Internet]. 2004;351(27):2817–26. Available from: http://dx.doi.org/10.1056/NEJMoa041588. 2. Sparano JA, Gray RJ, Makower DF, Pritchard KI, Albain KS, Hayes DF, et al. Adjuvant chemotherapy guided by a 21-gene expression assay in breast cancer. N Engl J Med [Internet]. 2018;379(2):111–21. Available from: http://dx.doi.org/10.1056/NEJMoa1804710. 3. Kalinsky K, Barlow WE, Gralow JR, Meric-Bernstam F, Albain KS, Hayes DF, et al. 21-gene assay to inform chemotherapy benefit in node-positive breast cancer. N Engl J Med [Internet]. 2021;385(25):2336–47. Available from: http://dx.doi.org/10.1056/NEJMoa2108873. Table 1 – Clinical and pathological characteristics of 197 hormone receptor positive, HER-2 negative early breast cancer patients who did the Oncotype DX® 21-Gene Recurrence Score assay. Data from medical records collected retrospectively of women diagnosed with early breast cancer between 2012 and 2022 from a single center in Brazil. Figure 1 – Probability of recurrence free survival in premenopausal patients according to age <=44 (blue line) or > 44-years-old (pink line). Data from medical records collected retrospectively of women with hormone receptor positive, HER-2 negative early breast cancer who did the Oncotype DX® 21-gene assay diagnosed between 2012 and 2022 from a single center in Brazil. Figure 2 – Probability of recurrence free survival in premenopausal patients according to histological grade. Tumor with histological grade 1 (blue line) or histological grade 3 (pink line). Data from medical records collected retrospectively of women with hormone receptor positive, HER-2 negative early breast cancer who did the Oncotype DX® 21-gene assay diagnosed between 2012 and 2022 from a single center in Brazil. Citation Format: Carolina Cavalcanti Gonçalves Ferreira, Julio Araujo, Shermann Brandão Rodrigues Moreira, Antônio Buzaid, Débora Gagliato. Clinical and pathological factors associated with Oncotype DX® 21-Gene recurrence score in patients diagnosed with early stage breast cancer in a low-middle income country [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 PO2-02-03.

Abstract PO2-03-05: Neoadjuvant anthracycline followed by Toripalimab combined with nab-paclitaxel in patients with stage IIA-IIIC triple negative breast cancer (NeoTENNIS): efficacy and safety results of a phase II study

Abstract Background: Immune checkpoint inhibitors(ICIs)have shown promising antitumor activity in triple negative breast cancer (TNBC) patients. Toripalimab, a novel PD-1 antibody, has been approved for the treatment in multiple solid tumors. However, the neoadjuvant use of toripalimab with chemotherapy has not been evaluated in TNBC patients. In addition, whether chemotherapy could sensitize the ICI treatment has not drawn conclusion yet. In this phase II trial, a sequential use of chemotherapy and anti-PD1 therapy was given in a neoadjuvant setting. The efficacy and safety of toripalimab were evaluated. Patients and methods: Female patients with histologically confirmed stage IIA to IIIC TNBC were included. Eligible patients received neoadjuvant therapy with four cycles of epirubicin-cyclophosphamide every 2 weeks followed by toripalimab (240 mg) every 3 weeks plus nab-paclitaxel weekly for 12 weeks. The primary endpoint was pathologic complete response (tpCR; ypT0/is ypN0) rate. Key secondary endpoints were breast pCR (bpCR; ypT0/is) rate, biomarker analysis, and safety. Results: Among 70 enrolled patients (median age, 51 years; 62.9% stage III), 66 patients completed study treatment without progression and received surgery after study treatment. Overall, the percentages of patients with a tpCR and bpCR were 55.7% (39 of 70 patients) and 58.6 % (41 of 70 patients), respectively. For women with CD8–positive and negative tumors, the tpCR rates were 66.0% and 30.0% (P = 0.006), respectively. Significant upregulation of CD8 positive cells after 4 cycles of epirubicin-cyclophosphamide induction chemotherapy (P = 0.011) were shown in sequential biopsy samples. Grade 3 or 4 treatment-related adverse events (TRAEs) occurred in 30 patients (42.9%), the most common of which were neutropenia (15.7%), leukopenia (14.3%) and alanine aminotransferase increase (4.3%). Most common immune-related AEs were hepatobiliary disorders (Grade 3, 7.2%), creatinine increase (all Grade 1-2, 2.8%) and hypothyroidism (all Grade 1-2, 2.8%). Conclusions: The addition of toripalimab to neoadjuvant chemotherapy is efficacious and safe in patients with locally advanced TNBC. Anthracycline-based chemotherapy could sensitize the ICI treatment with upregulated tumor immune response. The event-free survival results are expected with further follow up. Mechanisms of chemotherapy sensitization are still under investigation (ClinicalTrials.gov number: NCT04418154). Citation Format: Min He, Linxiaoxi Ma, Shuang Hao, Benlong Yang, Bingqiu Xiu, Ya-Yun Chi, Ruo-Hong Shui, Zhong-Hua Wang, Zhi-Ming Shao, Jiong Wu. Neoadjuvant anthracycline followed by Toripalimab combined with nab-paclitaxel in patients with stage IIA-IIIC triple negative breast cancer (NeoTENNIS): efficacy and safety results of a phase II 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 PO2-03-05.

Abstract PO2-02-07: Clinicopathological Features and Prognostic Role of HER2 Low in Early Breast Cancer: A real world study

Abstract Background: The definition of human epidermal growth factor receptor-2(HER2) low was proposed with the development of T-DXd, a novel antibody-drug conjugate (ADCs) targeting HER2 in the field of breast cancer (BC) treatments. However, whether HER2 low is a distinct subgroup is still an ongoing debate with mixed results. Current retrospective studies focused on HER2 low concentrated more on metastatic BC, less was known in early BC. The retrospective study was conducted based on HER2 low early BC to comprehensively analyze its clinicopathological features and prognostic roles compared with HER2 IHC0. Methods: This single institution retrospective study enrolled 999 early stage (stage I through III) HER2 negative invasive BC patients diagnosed at Chinese PLA General Hospital from January 2010 to December 2015. Tumors with HER2 immunohistochemical (IHC) score of 1+ or 2+ with negative in situ hybridization assay were defined as HER2 low. Clinicopathological characteristics s and survival outcomes including disease-free survival (DFS) and overall survival (OS) were compared between HER2 IHC0 and HER2 low groups. The correlations between HER2 expression and estrogen receptor (ER) status were determined by Mantel-Haenszel χ2 test. Cohen’s kappa coefficient (k) was adopted to evaluate the concordance between HER2 expression on primary tumors and matched biopsies. Results: 999 patients were eligible for inclusion criteria, among which the percentages of HER2 low in the whole cohort, HR positive group and HR negative group were 83.6%, 86.54%, 72.14% respectively. It was observed the presence of a significant higher proportion of ER level > 10% (p < 0.001), PgR positive (p < 0.001) and more patients who received endocrine therapy (p = 0.002). In HR positive group, clinicopathological features were balanced between HER2 IHC0 and HER2 low. In HR negative group, HER2 low manifested a higher proportion of invasive ductal type (p = 0.016) compared with HER2 IHC0. Survival analysis showed a significantly longer OS in HER2 low BC than HER2 IHC0. (HR: 0.458, 95%CI: 0.262-0.800, p = 0.0005). Nevertheless, the independent role was not reached in DFS. When stratified by HR status, patients with HER2 low in HR positive group demonstrated a longer OS than HER2 IHC0 (HR: 0.55, 95%CI: 0.273-1.105, p = 0.0385). The same trend was observed in HR negative group (HR: 0.385, 95%CI: 0.158-0.939, p = 0.0132). Neither the HR positive group nor the HR negative group achieved significant DFS. Besides, a positive correlation was observed between ER status and the rate of HER2 low (Mantel-Haenszel c2 test, p < 0.001, Pearson’s R = 0.159, P < 0.001). No regularity of survival differences between HER2 IHC0 and HER2 low was found in each ER level in the exploratory study. Finally, 119 patients who developed relapsed or metastatic disease were identified, with the most prevalent metastatic site being bone (31.1%), following by lung (16.80%) and lymph node (13.44%). Among 52 patients with matched biopsy samples, dynamic changes of HER2 IHC status were confirmed in both primary and relapsed statuses, with an discordance rate of 28.84% (K = 0.194, 95%CI: 0.168-0.219). conclusion: HER2 low expression breast cancer may not be regarded as a unique BC group in this real-world population due to similar clinicopathological features and prognostic roles especially in hormone-receptor positive cases. ER level was positively correlated with the rate of HER2 low population. Overall, whether HER2 low is a distinct subgroup remains to be supported and validated by more data both in clinical and molecular levels. Key words: HER2 low; Breast cancer; Clinicopathological Features; Prognosis; Molecular type Clinicopathological Features and Prognostic Role of HER2 Low in Early Breast Cancer: A real world study Citation Format: Ziqing Kong, Weihong Zhao. Clinicopathological Features and Prognostic Role of HER2 Low in Early Breast Cancer: A real world 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 PO2-02-07.

Abstract PO5-04-14: Quality of Life (QoL) among metastatic hormone receptor positive, HER2 negative breast cancer patients during first line systemic treatment

Abstract Background Current international guidelines recommend endocrine therapy combined with a CDK4/6 inhibitor as the preferred first line systemic treatment in patients diagnosed with metastatic hormone receptor positive (HR), HER2 negative breast cancer (BC). Randomized controlled trials that led to the approval of these agents in the first line disease setting are derived from controlled environments and selected patients. We aimed to assess real-world patients’ characteristics, safety and health related quality of life in a non-select cohort of patients being managed in a Brazilian private Cancer Center. Methods: We performed a cross sectional study at Beneficencia Portuguesa de Sao Paulo evaluating quality of life among patients with metastatic HR+/HER2 negative treated in the first line disease setting. Inclusion criteria included patients that received the combination of a CDK4/6i with any endocrine therapy (ET) between January 2018 and April 2023. Primary endpoint was quality of life assessed using the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire Core 30 (EORTC QLQ-C30) and EORTC QLQ-BR23, it is baseline, there is only one measurement for each patient. Results: We analyzed 72 patients who meet the inclusion criteria. Median age at diagnosis was 49 years old (ranging from 31 to 91). Approximately half of the population was premenopausal (51%). Palbociclib and abemaciclib were the most commonly used CDK4/6i, with 42 and 35% of patients, respectively. ECOG performance status was zero or one in almost the entire patient population analyzed (97%). 53% of the patients were diagnosed as de novo metastatic BC. Table 1 and 2 summarize the patients characteristics. Mean global health status was 75.4, with social and cognitive functioning scoring the highest (Mean 78.6 and 79.1, respectively). The most distressing symptom among the symptom scale was fatigue (Mean 27.2). Most symptoms and functioning scales did not meet the threshold for clinically meaningful differences between the different CDK4/6 inhibitors. Conclusion: Real-world data from our study is consistent with the historical expected health related quality of life among patients diagnosed with HR+/HER2 negative metastatic BC in the first line disease setting. Table. Citation Format: Débora Gagliato, Julio Antonio Araujo, Bianca Milena Verboski, Guilherme William Marcelino, Fabiana Nogueira Momberg, Gilmara Silveira da Silva, Rozana Mesquita Ciconelli, Antônio Buzaid. Quality of Life (QoL) among metastatic hormone receptor positive, HER2 negative breast cancer patients during first line systemic treatment [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 PO5-04-14.

Abstract PO1-13-03: Tumour infiltrating double negative (CD20+CD27- IgD-) B cells in high-risk early breast cancers. Friend or Foe??

Abstract Background: B cells exhibit diverse phenotypes and function and the complex interplay between different B cell subsets in the context of chemotherapy treated breast cancers remains unclear. Here, we investigate the dynamic changes in the B cell immune landscape before and after NACT treatment across different breast cancer subtypes. Methods: Treatment naïve, mid-treatment and post-NACT breast tumour, matched lymph node, blood and serum samples were profiled for B cell subsets and cytokines by flow cytometry, cytometry by time-of-flight (CyTOF) and Luminex technologies. Ex vivo autologous tumour organoid and immune cells cocultures to functionally assess the B-cell interactions across breast cancer subtypes were performed. Multiplex spatial analysis method was used to explore the dynamics of double negative B cell cellular crosstalk within the tumour and axillary lymph nodes. The results are being associated with treatment outcomes. Expression and activity of purinergic ectoenzymes within B cell subsets were also assessed by flow cytometry and high-performance liquid chromatography. Current work focusses on how these findings may relate to immunotherapy response, a new paradigm shift in the treatment of triple negative breast cancer patients. Results: We observed a significant expansion in the CD20+CD27−IgD− cells, also termed as double-negative (DN) B cells, within the TME of treatment naïve and post-neoadjuvant residual tumours compared to the periphery. Specifically, DN1 (CD20+ CD27−IgD− CD21+CXCR5+) cells represented the majority of DN B cells within the treatment naïve TME and in circulation. However, NACT promotes an expansion of the DN2 (CD20+CD27−IgD−CD21-CXCR5-) subset as well as a relatively uncharacterised DN3 (CD19+IgD−CD27−CXCR5−CD11c−) cell population. Preliminary analyses on how these changes (especially the enrichment of DN2 cells) relate to treatment response show significant expansion of DN2 cells in the periphery of poor responders to NACT, coupled with significantly reduced infiltration of DN2 into resistant residual tumours. Among circulating B, T and NK cells, B cells showed the highest CD73 and CD39 surface expression at baseline, but their expression significantly drops following NACT especially within the DN2 B cell subset. These ecto-5’-nucleotidases are known to play a critical role in B and T cell interactions. Spatial analyses between these cell types is ongoing. Conclusion: We report for the first time an enrichment of DN cells in breast cancer tumour tissue, specifically the expansion of DN2 cells following neoadjuvant chemotherapy. Functional analyses of tumour-infiltrated B-cells suggest that mechanistically, these B-cell subgroups may contribute to immunosurveillance and point to an important role of purinergic signalling in early breast cancers. Our study highlights the requirement for further investigation into the role of DN B cells in the context of chemo/immunotherapy resistance in breast cancers. Citation Format: Esme Carpenter, Paul Buckley, Thanussuyah Alaguthurai, Rosalind Graham, Helen Kakkassery, Gheed Alhity, Farhana Hossain, Sadiyah Mukhtar, Sheeba Irshad. Tumour infiltrating double negative (CD20+CD27- IgD-) B cells in high-risk early breast cancers. Friend or Foe?? [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 PO1-13-03.

Abstract PO3-16-05: Mitochondrial DNA mutation detection in tumors and circulating extracellular vesicles of triple negative breast cancer patients for biomarker development

Abstract Early detection of triple-negative breast cancer (TNBC) patients and their recurrence prediction are daunting tasks. We aim to develop mitochondrial DNA (mtDNA) based biomarkers to improve the management strategies of TNBC patients. We have undertaken mitochondrial genome (MG) enrichment and next-generation sequencing approaches to map the entire MG in 73 samples (64 tissues, 9 extracellular vesicle samples) from 32 highly-aggressive TNBC patients. Measurement of mtDNA and cardiolipin contents, in concert with NDUFB8 and SDHB proteins’ expression, was carried out in tumors and matched extracellular vesicles (EVs) of all the above TNBC patients. Overall, we identified 168 nonsynonymous mtDNA mutations, of which 73% (123/186) were coding and 27% (45/168) were non-coding. Twenty percent of mutations were nucleotide transversions. Respiratory complex I (RCI) appears to be the key target, which harbored 44% (74/168) of the overall mtDNA mutations. A panel of 11 hotspot mtDNA mutations was identified among 19-38% TNBCs, each of which was detectable in the matched EV samples with 82% specificity. Overall, 38% of the metastatic tumor-signature mtDNA mutations were detectable in matched EVs of the TNBC patients. An appreciable number of mtDNA mutations were homoplasmic (18%, 31/168), novel (14%, 23/168), and potentially pathogenic (9%, 15/168). The overall and RCI-specific mtDNA mutational load was recorded to be higher in African American (AA) compared to European American (EA) women with an exclusive abundance of respiratory complex (RC) protein NDUFB8 (RCI) and SDHB (RCII) therein. Increased mtDNA (p < 0.0001) content was measured in both tumors and matched EV samples along with an abundance of cardiolipin (p=0.0001) content in the EVs of the TNBC patients. Lethal tumor-signature mtDNA mutation detection and measurement of altered mtDNA and cardiolipin contents in the EVs at an early time point bear the potential to formulate noninvasive early detection and recurrence prediction strategies in TNBCs to improve the overall survival of the patients. Citation Format: Kunwar Vikramdeo, Shashi Anand, Sarabjeet Sudan, Paramahansa Pramanik, Seema Singh, Andrew Godwin, Ajay Singh, Santanu Dasgupta. Mitochondrial DNA mutation detection in tumors and circulating extracellular vesicles of triple negative breast cancer patients for biomarker development [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 PO3-16-05.

Abstract PO3-06-10: Real World Outcomes with Sacituzumab Govitecan in Metastatic Triple Negative Breast Cancer Patients: A Multi-Institution Study

Abstract Background Sacituzumab govitecan (SG) is approved for treatment of metastatic triple negative breast cancer (mTNBC) in the second line and beyond. Little is known about the real-world outcomes of SG. We aim to evaluate the real-world effectiveness and toxicity outcomes of SG in heterogenous heavily pretreated mTNBC patients (pts) to investigate the consistency of the outcomes in comparison to the clinical trial population. Methods A multi-center retrospective study of pts with mTNBC treated with SG in the US from January 2021 until May 2023 was conducted. Demographics and clinicopathological variables including site of metastases, prior lines of therapy, relative dose intensity (RDI), adverse events (AEs), HER2 immunohistochemistry (IHC) score at time of metastasis, clinical response, clinical benefit rate (CBR) defined as (complete response, partial response (PR) or stable disease (SD) > 6 months) and last follow-up were collected. For continuous variables, Mann-U Whitney and Kruskal Wallis tests were used to compare mean, median, standard deviation, and range. For categorical variables, Fisher's exact tests and Pearson Chi-square tests were used. Univariate and multivariate cox regression models examined RDI and survival outcomes. SAS v9.4 was used to perform statistical analysis at a significance level of 0.05. Results A total of 111 pts were analyzed. The median age was 58 years (range 29-84). The majority of pts were heavily pretreated: 59.1% received >3 prior lines of treatment (Tx) in the metastatic setting, 54.1% received prior immune checkpoint inhibitor (ICI), 8.1% received prior olaparib. 55% of pts had significant disease burden defined by >=3 organs involved by metastatic disease, with 22.5% having brain metastasis at the time of initiation of SG. Of note, 51% had primary refractory disease defined as relapse within 12 months of completion of adjuvant chemotherapy. 98.1% experienced any grade AEs, with the most common being anemia 63.1%. Grade 3 AEs occurred in 51.4% pts with neutropenia being the highest 32.4% followed by anemia 14.4%, diarrhea 7.2% and fatigue 7.2%. Tx interruptions and dose reductions due to AEs occurred in 52.3% of patients and Tx discontinuation rate due to AEs was 11.8%. Elderly pts (defined as >65 years) did not have higher rates of dose reductions due to AEs compared to young pts (< = 65 years) (37.8% vs 59.7 %), p=0.043). The median RDI is 92% (interquartile range (IQR) 33%-100%). The median RDI in elderly pts was 94% (IQR 50%-100%). Among pts in which response was assessed, objective response rate (ORR) was 26.6% (25 pts had PR), and 38.3% had SD. Interestingly, the rate of alopecia was higher in pts who had PR as the best response (28%), compared to 5.6% in pts who had SD, and 3% in progressive disease (PD) p=0.004. The median prior line of therapy in pts who had PR and SD as best response was 2 (IQR 1, 5) (IQR1, 12), respectively, compared to a median of 3 (IQR 1, 7) in pts with PD, p< 0.001. The CBR was 49% (46/94). The median duration of clinical benefit was 7 months IQR (2, 16) with median overall survival of 13 months IQR (2.5, 39) compared to 5.7 months IQR (0.03, 27) in pts without clinical benefit (p< 0.001). 56.9% (62/109) of pts had HER2 low disease and the clinical benefit rate in this subgroup was 14.3% (23/62). Conclusion: In a heavily pretreated cohort, SG retains clinical activity and tolerability in mTNBC. This is reassuring given pts on clinical trials tend to be healthier compared to real-world clinical practice. Citation Format: Sabah Alaklabi, Arya Mariam Roy, Paola Zagami, Nicole Held, Saba Shaikh, Lubna Chaudhary, Yara Abdou, Shipra Gandhi. Real World Outcomes with Sacituzumab Govitecan in Metastatic Triple Negative Breast Cancer Patients: A Multi-Institution 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 PO3-06-10.

Abstract PO3-25-11: Unprecedented responses to neoadjuvant sequential administration of Tocilizumab followed by cisplatin/docetaxel for locally advanced triple negative breast cancer patients

Abstract Background: Triple negative breast cancer (TNBC) remains a challenge for clinicians due to its aggressive behavior and scarcity of effective treatment. Interleukin 6 (IL-6) is well known to contribute to poor therapeutic gain, tumor relapse and aggressive tumor growth. Here we have explored targeting the IL-6 signaling pathway by Tocilizumab (Actemra) as a new potential therapeutic approach for the treatment of TNBC. Methods: The study population includes thirty (30) patients with (T2-T4, N0-3) stage (IIB-III) TNBC treated uniformly with Tocilizumab followed with cisplatin/docetaxel according to a traditional 3+3 design using a sentinel patient at each cohort. Eligible patients received Tocilizumab on day 1 followed by cisplatin/docetaxel on day 2 every 4 weeks for a total of six cycles. The primary end points were pathological complete response in breast and axilla (pCR) (ypT0/ypN0) and assessment for tolerability/toxicities profiles. Additionally, the status of the BRCA1 and BRCA2 genes was determined in all patients. Results: Eligible patients who were enrolled in this phase I/II trial had a median age of 42 years, with 63% premenopausal and 67% had nodal involvement at base line. The median tumor size was 45 mm (range 25-150 mm), stage III A/B 26% and stage IIIC 50%. Germline BRCA1/2 mutations represented 27%. The overall pCR and (RCB class 0+1) were 66% and 69%, respectively. Interestingly, pCR reached 81% in axilla, and 100% in patients with tumors bearing BRCA1/2 mutations. Interestingly, tocilizumab affected the blood level of several pro-carcinogenic cytokines. Conclusions: To our knowledge this novel therapeutic strategy is the first to report the inhibition of a cytokine signaling (a new class of biological therapy) in combination with chemotherapy for the intricate and hard-to-treat TNBC patients with unprecedented responses and acceptable tolerability/toxicities, which merits further investigation. Pending Patents: US Patent Application No. 18/122,839 European Patent Application No. 23 162 694.6 Citation Format: Taher Al-Tweigeri, Noura Alraouji, Asma Tulbah, Syed Akhtar, Meshari Alzahrani, Saleh Najjar, Dahish Ajarim, Kauser Suleman, Adher Al Sayed, Abdelilah Aboussekhra. Unprecedented responses to neoadjuvant sequential administration of Tocilizumab followed by cisplatin/docetaxel for locally advanced triple negative breast cancer patients [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 PO3-25-11.

Abstract PO2-18-11: Short-term Pre-OPerative Durvalumab (MEDI 4736) in early small triple negative breast cancer patients (POP-Durva)

Abstract Background: Immune checkpoint inhibitors (ICIs) are one of the major therapeutic advancements in cancer treatment. Anti-programmed cell death protein 1 (Anti-PD1)/PD-L1 ICIs have improved progression-free survival in patients with metastatic triple negative breast cancer (TNBC) and pathologic complete response (pCR) and event-free survival in patients with early TNBC. Nevertheless, some patients treated with anti-PD(L)1 ICIs experience recurrence or do not achieve sustained clinical benefit. In addition, very interesting data show the existence of a subgroup of patients with exceptional tumour responses to monotherapy with anti-PD(L)1 ICIs. These exceptional responses are observed in various tumour types, such as colorectal or breast cancer. Although in colorectal cancer, the determinants for this extreme sensitivity to immunotherapy treatment are identified (existence of MSI) in breast cancer, this is not the case. There is still a lack of knowledge about predictive biomarkers and mechanisms of action for ICIs. Trial Design: POP-Durva (NCT05215106) is a prospective, one-arm-only study aiming at determining the pCR rate after two administrations of Durvalumab monotherapy in patients with stage I TNBC. This window-of-opportunity study will recruit 195 consecutive cases of stage I TNBC (ER < 1%, PR < 1%, HER2 negative) and TILs≥5%, eligible for short-term treatment with durvalumab. Study treatment consists of two administrations of intravenous Durvalumab monotherapy, 10mg/kg, at two weeks intervals. After study treatment, patients will receive a standard treatment strategy (surgery or neoadjuvant systemic treatment) as per physician choice. The primary endpoint is the pCR rate after treatment with Durvalumab, defined as the absence of invasive disease in the breast and negative axillary nodes (ypT0/yTis ypN0). Assessment of the primary endpoint will be performed at the surgery or at the biopsy at the end of treatment) for patients undergoing neoadjuvant treatment. For patients in whom neo-adjuvant therapy is the first standard treatment strategy (i.e. after study treatment) a breast ultrasound-guided biopsy is mandatory at the end of the treatment visit. If the biopsy-proven residual disease is demonstrated, patients can receive standard neoadjuvant therapy at the discretion of the treating investigator. Patients with biopsy-proven residual disease will be considered as having no pCR. Those with a complete response may proceed directly to surgery. The expected pCR rate with Durvalumab monotherapy is 20%. The sample size of 195 patients will allow us to estimate this expected pCR rate with a 95% confidence interval of a precision of 6.2%. Secondary objectives are objective response rate and safety. Exploratory objectives are to: a. describe immune cell dynamics associated with exceptional responses to ICI (using spectral cytometry analysis), b. describe somatic genetic contributions to the determination of immune responsiveness (using whole exome sequencing (WES) and in a subset of patient's single-cell RNA-seq), c. characterize tumour cells – immune cells' interaction/spatial distribution(using imaging mass cytometry), d. explore the association between gut microbiome composition/signatures predictive of response to ICI (using 16s rRNA sequencing) and e. identify predictive tissue/blood-based biomarkers of response and to anti-PD(L)1 ICIs therapy. A total of two dedicated FFPE samples and two fresh biopsies will be collected at the time of inclusion and at the end of treatment biopsy or on the surgical specimen. In addition, we will collect stool samples pre and at the completion of all Durvalumab treatments and blood samples at the time of inclusion, during treatment (before each Durvalumab administration) and at the end of treatment for serum and plasma extraction and whole blood to serve as a control for WES. Citation Format: Joana Mourato Ribeiro, Isabelle Pic, Quentin Blampey, Elie Rassy, Nusaibah Ibrahimi, Laura Salabert, Olivier Trédan, Monica Arnedos, Semih Dogan, Kamar Serhal Serhal, Clementine Mahaut, Alessandro Viansone, Salim Laghouati, Barbara Pistilli, Charles-Antoine Dutertre, Magali Lacroix-Triki, Jean-Yves Scoazec, Lisa Derosa, Laurence Zitvogel, Corinne Balleyguier, Nadege Bercovici, Paul-Henry Cournede, Stefan Michiels, Fabrice André. Short-term Pre-OPerative Durvalumab (MEDI 4736) in early small triple negative breast cancer patients (POP-Durva) [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 PO2-18-11.

Abstract PO3-23-07: Evaluation of the role of axillary ultrasound to estimate axillary nodal burden to guide de-escalation of upfront axillary surgery in node positive early breast cancer patients

Abstract Background: Axillary surgery is now routinely de-escalated in clinically node negative breast cancer patients with limited axillary nodal burden (up to 2 involved sentinel nodes) based on the results of ACOSOG-Z0011 and AMAROS trials. However, patients with proven axillary metastasis following on ultrasound (AUS) guided core needle biopsy (CNB), undergoing primary surgery are still subjected to an axillary lymph node dissection (ALND) irrespective of the magnitude of the axillary nodal burden. If we could predict axillary nodal burden with a low false negative rate (FNR) for the presence of extensive axillary nodal involvement, we can then hypothesize that axillary surgery could be safely de-escalated in this cohort of patients. We investigated whether pre-operative AUS suggesting limited axillary burden is sensitive enough to rule out gross axillary disease burden. Methods: A single institution retrospective study. We undertook an electronic chart review of all T1 to T3 patients undergoing upfront ALND with either mastectomy or breast conserving surgery between January 2019 and June 2023. Patients with palpable axillary nodes, locally advanced breast cancer or a completion ALND after positive sentinel lymph node biopsy (SLNB) were excluded from the study. Clinical and pathological characteristics associated with nodal burden of disease were evaluated. Limited axillary burden was defined as < 2 involved nodes with ≥3 taken as gross nodal burden for primary analyses. Sensitivity analyses were carried out with limited axillary burden defined as < 3 involved nodes (N1) and ≥4 (N2) taken as gross nodal burden. Subgroup analyses in T1 or T2 tumors were carried out as well. The probabilities of discordant events, defined as limited burden on AUS-CNB but gross burden on final histopathology evaluation (HPE), assuming 10% FNR, were estimated using inverse cumulative binomial distribution function. Results: Data on the exact number of suspicious nodes on AUS were missing for 2 patients, therefore, the final study cohort included 39 patients. The correlation between AUS nodal burden and that on HPE was moderate (Spearman’s rho = 0.48; p = 0.0018). The sensitivity and specificity of AUS in identifying gross nodal burden were 61% and 81% respectively. Observation of 9 discordant events in 22 patients with low burden on AUS ruled out an FNR of < 10% with 99.99% certainty. The sensitivity and specificity in T1/T2 subgroup were 60% and 75% respectively. The sensitivity analyses classifying N1 as limited and N2 as gross axillary burden showed the sensitivity and specificity of 35% and 82% respectively and an FNR of < 10% was ruled out with 99.996% certainty. Conclusion: Pre-operative AUS alone lacks the sensitivity and specificity to accurately predict the true axillary nodal burden to safely guide de-escalation of axillary surgery. AUS followed by targeted axillary dissection (TAD) in conjunction with a dual technique SLNB may provide the desired sensitivity and specificity to guide de-escalation of axillary surgery. A prospective evaluation of this approach is merited. Given the limited number of patients that could be enrolled in such prospective study from individual institutions, an international collaborative effort is needed to address this important research question. Citation Format: Nidhi Garg, Mangesh Thorat, Hisham Hamed, Ashutosh Kothari. Evaluation of the role of axillary ultrasound to estimate axillary nodal burden to guide de-escalation of upfront axillary surgery in node positive early breast cancer patients [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 PO3-23-07.

Abstract PO5-14-05: Circulating tumor DNA fraction correlates with residual cancer burden post-neoadjuvant chemotherapy in triple negative breast cancer patients

Abstract Background: Pathologic response after preoperative/neoadjuvant chemotherapy is a continuum that can range from no residual cancer to extensive disease. Viable cancers can shed tumor DNA into the blood and we hypothesized that plasma ctDNA levels can reflect pathologic response as continuum. Patients and methods: Post-neoadjuvant plasma samples were obtained after completion of chemotherapy but before surgery from patients with stage I to III TNBC who received treatment with durvalumab concurrent with weekly nab-paclitaxel followed by dose dense doxorubicin/cyclophosphamide in a single arm neoadjuvant clinical trial (NCT02489448). Up to 3 mL of blood was collected into EDTA- and heparin- containing vacutainer tubes, and plasma cfDNA was extracted and twice purified in the lab at Predicine Inc. Pathologic response was quantified on a continuous scale using the Residual Cancer Burden (RCB) score, and also categorized as RCB-0 (complete pathologic response, n=21), -I (minimal residual cancer, n=7), -II (moderate residual cancer, n=13), and -III (extensive residual cancer, n=3). Median follow-up was 35 months (range 25-70 months). Tumor whole exome sequencing (WES) data was previously generated using HiSeq 4000 at the Yale Center for Genome Analysis (dbGaP: PRJNA558949). A personalized MRD panel of up to 60 personalized variants per patient was designed based on the tumor WES data, and ultra-deep next-generation sequencing (100,000X) of plasma cfDNA was performed using the PredicineBEACON assay for MRD detection by Predicine. CtDNA positivity (MRD) was defined as a weighted score equivalent to 2 or more tumor variants detected in the plasma. cfDNA tumor fraction was measured based on mutant allele fraction of observed variants. Adjusted tumor fraction could be confidently measured for 37 out of 44 patients that had enough confidently called personalized ctDNA variants. We compared tumor fraction versus RCB score as continuous variables, and also compared tumor fraction between RCB categories as ordinal variables. Invasive disease-free survival was examined by Kaplan-Meier analysis. Bioinformatic data analysis was performed using Graphpad Prism and R. Results: 44 of 48 plasma samples yielded successful cfDNA generation and sequencing. Six patients (13.6%) were MRD positive. Among these 6 cases, 3 had RCB-0 response (14.3% of RCB 0 cases), 1 had RCB II response (7.7% of RCB II cases), and 2 had RCB III response (66.7% of RCB III cases). The median cfDNA tumor fraction of patients with pathological complete response to treatment (pCR) was significantly lower than patients with residual disease (RD) (0.06% vs. 0.3%, p=0.02). There was a positive correlation between RCB scores and tumor fraction (r= 0.45, Spearman). Tumor fraction was more strongly correlated with later recurrence than a binary ctDNA positivity call. Tumor fraction was significantly higher in patients that later experienced local or metastatic recurrence (n=8) compared to those with no evidence of disease (n=29) (Wilcoxon test, p=0.02). Both ctDNA positive RCB III cases had metastatic recurrence while the remaining 4 ctDNA positive cases currently remain recurrence-free. Mutational genomic landscape of both tumor WES and plasma ctDNA samples identified hotspot mutations in 19 cancer-associated genes. Novel hot-spot mutations were observed in the plasma of two patients following treatment. TP53 mutations were highly prevalent in tissue and plasma, however no significant association of mutation of any gene with treatment response was detected. Conclusions: PredicineBeacon MRD assay was successfully performed on 3 mL plasma samples collected using from EDTA and heparin-containing tubes. Tumor fraction correlated with residual disease, RCB score and disease recurrence. Citation Format: Naing Lin Shan, Billie Gould, Kim Blenman, Julia Foldi, Pan Du, Frank Zhang, Myles Walsh, Lajos Pusztai. Circulating tumor DNA fraction correlates with residual cancer burden post-neoadjuvant chemotherapy in triple negative breast cancer patients [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 PO5-14-05.

Abstract PO5-13-07: Prediction of recurrence in triple negative breast cancer patients after receiving neoadjuvanttreatment using plasma metabolomics

Abstract Background Early-stage triple-negative breast cancer (TNBC) is usually treated with neoadjuvant chemotherapy (NADC), but prognosis remains poor compared with other BC subtypes. Unfortunately, less than 30% of BC patients achieve pathological complete response (pCR) to NADC and the overall survival of TNBC when cancer spreads is estimated at 10-13 months. Complete response is associated with improved progression-free and overall survival rates, but more accurate prognostic markers are needed. In this study, we assessed the prognostic value of blood circulating metabolites by using targeted-based metabolomics. Methods Patients received standard neoadjuvant chemotherapy with epirubicin plus cyclophosphamide followed by paclitaxel. Blood samples were obtained upon completion of chemotherapy and before surgery. Pathological response to treatment was recorded according to the Miller & Payne system, and categorized as partial (MP 1, 2, & 3) or complete response (MP 4 & 5). Blood samples were collected in EDTA tubes, centrifuged and plasma was stored at -80°C. After QC standard addition and methanol extraction of proteins, four fractions of the resulting extract were analysed: two by reverse-phase/UPLC-MS/MS methods with positive ion mode electrospray ionization (ESI), one by reverse phase/UPLC-MS/MS with negative ion mode ESI, and one by hydrophilic interaction liquid chromatography/UPLC-MS/MS) by Metabolon using a Thermo Scientific Q-Exactive mass spectrometer with a heated electrospray ionization source and an Orbitrap mass analyser. Using Metabolon's hardware and software, raw data were extracted, identified, QC processed and quantified using the area under the curve (AUC). Identified compounds were compared with library entries of purified standards or recurrent unknown entities. The prognostic capacity of each metabolite was assessed using BRB ArrayTools. Selected metabolites were validated using a targeted approach using compound standards as follows. Plasma samples were re-analysed by UPLC/MS using a Vanquish LC coupled to an Orbitrap Exploris 240 MS (Thermo Fisher Scientific) with positive and negative ionization mode ESI under polarity switching. Identification of compounds were performed by comparison of retention times (against in-house authentic standards), accurate mass (with an accepted deviation of 3ppm), and MS/MS spectra. These analyses were carried out by MS-Omics (Denmark). Results Twenty patients treated in the Medical Oncology Unit of the University Hospital of Jaén were recruited. Median age was 50 (31-76). Twelve patients obtained a pathological complete response. Median follow-up after surgery was 25 months. Seven patients eventually had distant metastases (2 in the lungs, 1 in the brain, 1 in the bones and 3 multi-site). Metabolon untargeted analysis identified and quantified 985 metabolites, 789 after xenobiotics exclusion. Survival analysis identified 16 metabolites related with distant relapse (p< 0.05). The ten metabolites with lower p-value were selected for targeted validation. Ms-Omics pipeline allowed absolute quantification of 5 metabolites, 3 of them showing high correlation (R >0.7) between both measurements (targeted and untargeted). Validation of the prognostic value of the candidate metabolites is ongoing in a larger TNBC cohort. Conclusions Metabolomics is a useful tool for the detection of simply assessable and cost-effective prognostic biomarkers in TNBC. Easily monitoring the presence of minimal residual disease is worth to be settled up in the clinical practice for the most aggressive molecular subtype of breast cancer. In this work we have defined a set of metabolites that could predict distant relapse events in TNBC patients treated with neoadjuvant chemotherapy. Further analyses are being carried out to validate the prognostic value of the proposed candidate metabolites. Citation Format: Pedro Sánchez-Rovira, Rocio Urbano-Cubero, Angelo Gamez Pozo, Carmen González-Olmedo, Alicia Cano-Jimenez, Andrea Zapater- Moros, Leticia Díaz-Beltrán, Lucia Trilla-Fuertes, Mariana Díaz-Almirón, Enrique Espinosa, Pilar Zamora, Juan Angel Fresno Vara. Prediction of recurrence in triple negative breast cancer patients after receiving neoadjuvanttreatment using plasma metabolomics [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 PO5-13-07.

Abstract PO2-06-10: Prevalence of genomic alterations in Xerna tumor microenvironment subtypes in triple negative breast cancer patients

Abstract Introduction: Immune checkpoint inhibitors (ICI) are an important therapeutic option for patients with triple negative breast cancer (TNBC). However, identification of patients most likely to respond is challenging. PD-L1 positivity by immunohistochemistry is the standard biomarker used for ICI therapy selection in TNBC. However, other biomarkers, such as analysis of the tumor microenvironment (TME) may be more accurate in predicting response. The XernaTM TME Panel uses RNA sequencing data and machine learning to analyze the TME, utilizing the angiogenic and immunogenic biology of the TME to classify tumors into four TME subtypes. In this study, the distribution of Xerna TME subtypes and associated genomic alterations in TNBC were investigated for their potential use in therapy selection. Methods: A total of 203 TNBC patient samples underwent tumor-normal whole-exome, whole-transcriptome sequencing testing with the OncoExTraTM assay. The whole-transcriptome expression data were analyzed using the Xerna TME Panel to assign each sample to one of four subtypes: Immune Active (IA), Immune Suppressed (IS), Immune Desert (ID) and Angiogenic (A). The IA and IS subtypes both have high immune scores that may be particularly sensitive to ICI therapy. Actionable alterations, defined as those with FDA-approved matched therapies in any cancer, with matched clinical trials, or with evidence in cancer guidelines or the literature for possible matched therapies, were also identified and associations across Xerna subtypes were explored. Results: Approximately half (100 of 203; 49.3%) of the patient samples had high (IA+IS) immune subtypes (Table 1). Targetable alterations associated with an FDA-approved therapy were present in 114 (56.2%) patients. No biomarkers were significantly associated (p < 0.05) with high (IA+IS) versus low (ID+A) immune scores. Biomarkers associated with ICI response, namely mismatch repair gene alterations (MSH2/3/6, MLH1/3, PMS1/2), high tumor mutational burden (TMB-high) and microsatellite instability were detected in only 6 (3.0%), 3 (1.5%) and 1 (0.5%) patient samples respectively, and all but 1, an MSH6 alteration, were in high immune subtype samples. Conclusions: The Xerna TME Panel classified 49.3% of TNBC patient tumors to IA or IS, suggesting they may respond to ICI therapy. Many (56.2%) patient tumors harbored alterations associated with FDA-approved therapies, providing the potential for novel combination therapies. These findings warrant further study and clinical validation in TNBC patients treated with ICI therapy. Table 1. Frequency of actionable biomarkers that were present in at least 10 (5%) TNBC patient samples. Citation Format: Gargi Basu, Janine Lobello, Snehal Thakkar, Jessica Aldrich, Matthew Halbert, Patrick Eimerman, Cynthia Flannery, Nishitha Therala, David Hall, Daniel Pointing, Lea Vohar, Roman Luštrik, Luka Ausec, Mark Uhlik, Seema Iyer, Laura Benjamin, Frederick Baehner. Prevalence of genomic alterations in Xerna tumor microenvironment subtypes in triple negative breast cancer patients [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 PO2-06-10.

Abstract PO2-06-13: Promising clinical performance of 89Zirconium-labelled Girentuximab PET-CT for imaging metastatic triple negative breast cancer patients (OPALESCENCE)

Abstract Aim: Triple Negative Breast Cancer (TNBC) is aggressive, often with a metastatic evolution and drug-resistant with limited therapeutic options. Evaluating new markers is an unmet need. Recently, the combination of anti-angiogenic and targeted hypoxia effectors agents proved to enhance therapy response. Indeed, anhydrase Carbonic-IX (CA-IX), a hypoxia-mediated breast tumor growth regulator, is important for the BC stem cells maintenance within hypoxic region and is highly overexpressed in TNBC. This pilot prospective study “OPALESCENCE” (NCT04758780) aimed at assessing PET/CT with 89Zr-labeled girentuximab (89Zr-TLX250) targeting CA-IX in 12 metastatic TNBC patients. Methods: Patients underwent FDG and 89Zr-TLX250 PET-CT and conventional imaging (CI) if needed (CT, US, mammography, brain MRI). Without any premedication or dietary preparation, patients received a single slow intravenous administration of 37±10% MBq 89Zr-TLX250 (10 mg). Day 3 or 5 post injection, a skull to mid-thigh PET/CT was acquired with 10 minutes acquisition time per bed position. The gold standard was determined by FDG PET/CT, CI and follow-up; lesion detected at least by 2 modalities was considered as true positive. Immunohistochemistry (IHC) was performed with Bond RX fully automated research stainer with CA-IX antibody (Leica, clone TH22). Staining was evaluated with semi-quantitative analysis (percentage and intensity of tumor cells expression). Human anti-chimeric antibody (HACA) were sampled but will be determined at study end. Results: Enrolment has been completed, a total of 273 lesions confirmed by gold standard as shown on table 1 were detected in 12 patients (231 by 89Zr-TLX250 and 264 by FDG PET/CT). Overall sensitivity of 89Zr-TLX250 PET/CT was 87.5%, with 100% sensitivity for breast, skin, adrenal gland and brain and 88.0%, 91.9% for nodes and bone respectively. Overall sensitivity for FDG-PET/CT was 96.7%. According to table 2, 6 patients had 100% of their lesions highlighted by 89Zr-TLX250 PET. In addition, for 2 other patients only one of the lesions was not detected by immunoPET. 89Zr-TLX250 PET therefore detected almost all of the metastatic lesions in 67% of the patients. For 8/12 patients, IHC was analysed and for 6 patients, CA-IX expression lesions was from 100% to 10% with an intensity from 3+ to 2+, whereas two patients presented no Ca-IX expression on tumour lesions. No 89Zr-TLX250 safety issue was reported. Conclusion: 89Zr-TLX250 PET/CT seems very promising because it allows the CA IX status lesions knowledge on whole body scale with a minimally invasive way, unlike the information provided by biopsies corresponding to only 1 or 2 lesions studied. Moreover, these results illustrated interest of 89Zr-TLX250 PET/CT as targeting agent for TNBC patients leading above all to a theranostic approach possibility. Study analysis (specially IHC, HACA and semi-quantitative PET/CT analysis) is ongoing and supplementary data will be presented during the congress. This is an investigator initiated trial. Investigational medicinal product was provided by Telix Pharmaceuticals. Table 1: Sensitivity of 89Zr-TLX250 PET, FDG PET, and conventional imaging (US, brain MRI and Mammography). Table 2: Number of confirmed lesions according to Gold Standard detected by 89Zr-TLX250 PET/CT (iPET), FDG PET/CT and CI for each patients. Citation Format: Caroline Rousseau, Marie Francoise Heymann, Jean Sebastien FRENEL, Elise Picot-Dilly, Maelle Le Thiec, Manon Taupin, Alexis Mouton, Emmanuelle Bourbouloux, Agnès Morel, Nadia Allam, Amélie Mallet, Mario Campone, Ludovic Ferrer, Françoise Kraeber-Bodéré. Promising clinical performance of 89Zirconium-labelled Girentuximab PET-CT for imaging metastatic triple negative breast cancer patients (OPALESCENCE) [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 PO2-06-13.

Abstract PO1-10-08: Building awareness of triple negative breast cancer: Results from the Canadian Breast Cancer Network national survey

Abstract Background: Assessing the education, information and support needs of Canadians diagnosed with breast cancer involves categorizing and tailoring topics and methods of delivery but, most importantly, it must be rooted in an understating of the patient. In 2022, the Canadian Breast Cancer Network (CBCN) initiated a project to identify the needs of the Canadian breast cancer population, determine differences between those diagnosed with triple negative breast cancer (TNBC) compared to non-TNBC patients and develop tailored, focused programs and materials as a result of the findings. Methods: CBCN conducted a series of 45-minute key informant interviews (7) with patients and oncologists to determine needs, gaps, programs, and materials for triple negative breast cancer patients in Canada. Five 90-minute patient focus groups (32 participants) were conducted to enhance the interviews. One group was specifically for metastatic patients. Findings from the interviews and focus groups were used to inform the questions for an online survey open to all Canadians diagnosed with breast cancer which was fielded May 1 to June 10, 2022. The data analysis began in September 2022 and is on-going. Results: While 47.9% of TNBC respondents (versus 51.3% of non-TNBC patients) said that they were aware of different types and subtypes of breast cancer, 70.6% of patients reported they were not aware of the term “triple-negative breast cancer” and only learned about at diagnosis. 69.9% of TNBC patients said that the person giving them their diagnosis used the term – triple-negative breast cancer. 54.5% reported being provided with specific details about their TNBC diagnosis. This included details about: the aggressive nature of TNBC (76.8%), treatments (67.6%), treatment goals (56.3%), and the urgency of beginning treatment (66.2%). TNBC patients reported that in retrospect, more information on clinical trials (41.7%), the long-term side effects of treatment (38.6%) and post-treatment follow-up (32.5%) should have been included in the discussion at diagnosis. Conclusions: Breast cancer is not a monolithic disease. TNBC impacts 10-20% of the breast cancer population. A majority of those diagnosed with TNBC in the survey were not even aware of this subtype. Building awareness of TNBC, its risk factors and different treatment needs in the public at large and among the breast cancer community could facilitate discussions with healthcare providers and assist researchers seeking new treatments and, most importantly, provide an informed voice for those with TNBC. Making the most current, evidence-based TNBC information and resources available to both patients and providers at diagnosis could build trust and understanding of the differences in treatment and follow up and instill confidence in the overall patient experience. Citation Format: Kathleen D. Swiger, Scott Richter, Bukun Adegbembo, Cathy Ammendolea. Building awareness of triple negative breast cancer: Results from the Canadian Breast Cancer Network national survey [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 PO1-10-08.