Post-neoadjuvant Chemotherapy Research Articles

Contrast-enhanced ultrasound features as potential biomarker for prediction of breast cancer recurrence.

Purpose To investigate the associations between contrast-enhanced ultrasound imaging features and disease recurrence among patients with locally advanced breast cancer treated with neoadjuvant chemotherapy. Materials and Methods In the study, pre- and post-neoadjuvant chemotherapy contrast-enhanced ultrasound images of 43 patients with breast cancer were retrospectively analysed. Post-acquisition image processing involved the placement of freehand-drawn regions of interest, followed by the generation of blood flow kinetics representing blood volume and velocity for these regions of interest. Qualitative and quantitative contrast-enhanced ultrasound parameters were compared to predict recurrence, and receiver operating characteristic analysis was used to evaluate predictive ability. Results Among the 43 patients, 10 (23%) exhibited disease recurrence (median [range]: 27 [4-68] months). Post-neoadjuvant chemotherapy peak enhancement, wash-in area under the curve, wash-out area under the curve, and wash-in and wash-out area under the curve (p=0.003, p=0.004, p=0.026, and p=0.014, respectively) differed between the no-recurrence and recurrence groups. The area under the receiver operating characteristic curve (0.88; 95% confidence interval: 0.75-1.00) for post-neoadjuvant chemotherapy peak enhancement was the highest among the contrast-enhanced ultrasound parameters, with a cut-off of 13.33 arbitrary units. Conclusion Higher peak enhancement on post-neoadjuvant chemotherapy contrast-enhanced ultrasound images were associated with recurrence in women with locally advanced breast cancer and is a potential biomarker of tumour recurrence.

Immunohistochemical profile of triple negative breast cancers: SOX10 and AR dual negative tumors have worse outcomes.

Triple negative breast cancer (TNBC) refers to an estrogen receptor negative, progesterone receptor negative, and HER2-negative breast cancer. Although accepted as a clinically valid category, TNBCs are heterogeneous at the histologic, immunohistochemical, and molecular levels. Gene expression profiling studies have molecularly classified TNBCs into multiple groups, but the prognostic significance is unclear except for a relatively good prognosis for the luminal androgen receptor (LAR) subtype. Immunohistochemistry (IHC) has been used as a surrogate for basal and luminal subtypes within TNBC, but prognostication of TNBC using IHC is not routinely performed. We aimed to study immunophenotypic correlations in a well-annotated cohort of consecutive TNBCs, excluding post-neoadjuvant chemotherapy cases. Tissue microarrays were constructed from a total of 245 TNBC cases. IHC stains were performed and consisted of luminal (AR, INPP4B), basal (SOX10, Nestin, CK5, EGFR), and diagnostic (GCDFP15, mammaglobin, GATA3, TRPS1) markers. Survival analysis was performed to assess the significance of clinical pathologic variables including age, histology, grade, lymphovascular invasion [LVI], Nottingham prognostic index [NPI] category, AJCC stage, stromal tumor-infiltrating lymphocytes at 10% increment, CD8+ T-cell count, Ki-67 index, PD-L1 status, and chemotherapy along with the results of IHC markers. Apocrine tumors show prominent reactivity for luminal markers and GCDFP15 while no special type carcinomas are often positive for basal markers. TRPS1 is a sensitive marker of breast carcinoma but shows low or no expression in apocrine tumors. High AJCC stage, lack of chemotherapy, and dual SOX10/AR negativity are associated with worse outcomes on univariable as well as multivariable analysis. LVI and higher NPI category were associated with worse outcomes on univariable but not multivariable analysis. The staining for IHC markers varies based on tumor histology which may be considered in determining breast origin. Notably, we report that SOX10/AR dual negative status in TNBC is associated with a worse prognosis along with AJCC stage, and chemotherapy status.

Longitudinal ultrasound-based AI model predicts axillary lymph node response to neoadjuvant chemotherapy in breast cancer: a multicenter study.

Developing a deep learning radiomics model from longitudinal breast ultrasound and sonographer's axillary ultrasound diagnosis for predicting axillary lymph node (ALN) response to neoadjuvant chemotherapy (NAC) in breast cancer. Breast cancer patients undergoing NAC followed by surgery were recruited from three centers between November 2016 and December 2022. We collected ultrasound images for extracting tumor-derived radiomics and deep learning features, selecting quantitative features through various methods. Two machine learning models based on random forest were developed using pre-NAC and post-NAC features. A support vector machine integrated these data into a fusion model, evaluated via the area under the curve (AUC), decision curve analysis, and calibration curves. We compared the fusion model's performance against sonographer's diagnosis from pre-NAC and post-NAC axillary ultrasonography, referencing histological outcomes from sentinel lymph node biopsy or axillary lymph node dissection. In the validation cohort, the fusion model outperformed both pre-NAC (AUC: 0.899 vs. 0.786, p < 0.001) and post-NAC models (AUC: 0.899 vs. 0.853, p = 0.014), as well as the sonographer's diagnosis of ALN status on pre-NAC and post-NAC axillary ultrasonography (AUC: 0.899 vs. 0.719, p < 0.001). Decision curve analysis revealed patient benefits from the fusion model across threshold probabilities from 0.02 to 0.98. The model also enhanced sonographer's diagnostic ability, increasing accuracy from 71.9% to 79.2%. The deep learning radiomics model accurately predicted the ALN response to NAC in breast cancer. Furthermore, the model will assist sonographers to improve their diagnostic ability on ALN status before surgery. Our AI model based on pre- and post-neoadjuvant chemotherapy ultrasound can accurately predict axillary lymph node metastasis and assist sonographer's axillary diagnosis. Axillary lymph node metastasis status affects the choice of surgical treatment, and currently relies on subjective ultrasound. Our AI model outperformed sonographer's visual diagnosis on axillary ultrasound. Our deep learning radiomics model can improve sonographers' diagnosis and might assist in surgical decision-making.

Breast Conserving Surgery Post Neo-Adjuvant Chemotherapy for Locally Advanced Breast Carcinoma in a Developing Country: Is It Safe?

Breast conserving surgery (BCS) is the standard treatment for early breast cancer and has similar survival with mastectomy. The role of BCS in locally advanced breast cancer (LABC), post neoadjuvant chemotherapy (NACT), is controversial. Surgeons, especially in developing countries, fear higher margin involvement and local recurrence (LR) in BCS. The aim of this study was to determine the LR in BCS compared to mastectomy in LABC post NACT and to ascertain the percentage of involved surgical margins following both methods of surgery. This was a retrospective study of breast cancer patients seen in Universiti Kebangsaan Malaysia Medical Centre (UKMMC). All patients had NACT followed by either mastectomy or BCS. The patients with Her2 enriched carcinomas did not have access to targeted therapy (Trastuzumab or Pertuzumab). The patients with ill-defined tumours underwent ultrasound assessment in the surgical clinics. All had post-operative radiotherapy. All with ER or PR positive cancers were given Tamoxifen for a minimum of 5 years. This study demonstrated that BCS post NACT was safe to be performed in selected patients with LABC in a developing country.

Abstract PO4-20-05: An open label phase III randomized trial to evaluate the efficacy of Post-chemotherapy Axillary Conservation Surgery in breast cancer (PACS)

Abstract Background- Axillary lymph nodes (ALN) status is the most important prognostic factor in breast cancer. Traditionally, a complete axillary lymph node dissection (ALND) has been standard of care for those patients who have a positive node pre-chemotherapy. However, lately axillary conservation is paving its way in the post-chemotherapy setting as well to avoid significant morbidity of ALND. Most sentinel node biopsy studies have failed to achieve the desired false negative rate(FNR). (Boughey JC et al, JAMA. 2013 Oct; Kuehn T et al, Lancet Oncol. 2013; Boileau JF et al, J Clin Oncol. 2015 Jan).We previously reported a low FNR of low axillary sampling (LAS) in the post-chemotherapy setting. (Parmar et al, JCO-GO, 2021) We are conducting a phase III, randomised controlled trial of LAS versus complete ALND in post-chemotherapy negative (ypN0) axilla. Aims and objectives- The primary objective is to assess the non-inferiority of LAS in patients who are rendered ypN0 by pre-operative chemotherapy with disease-free survival as primary end point. The secondary objectives are comparing the morbidity of ALND (lymphedema, paraesthesia, and shoulder dysfunction) in the LAS and ALND arms, and to evaluate the impact on overall survival, local, regional, and distant recurrence free survival and quality of life. Trial design- This is a prospective, open label, randomised, phase III trial where histologically proven, non-metastatic, cT1-4,N0-2 breast cancer patients who are rendered ycN0 after pre-operative systemic chemotherapy are being accrued. Patients with prechemo N3 disease, inflammatory breast cancer, recurrent disease, pregnancy associated breast cancer are being excluded from the study. The chemotherapy regimens and surgical assessment is as per standard institutional protocols. After obtaining informed consent, patients undergo LAS during surgery and lymph nodes(LN) are sent for frozen section analysis. If any LN is found to be involved, a complete ALND is carried out. If the staging procedure is negative, then patients are randomised into 2 groups- observation v/s complete ALND. Stratification factors are T stage, N stage, Hormone receptor status, Her2 receptor status and number of chemotherapy cycles taken. Morbidity assessment is done with- Constans shoulder score, arm volumetry, paraesthesia assessment, and a QOL questionnaire- Self-reported Breast cancer Lymphedema Symptom Experience Index (BCLSEI). A baseline assessment pre-surgery is followed by 6 monthly morbidity assessments and regular oncologically relevant follow-up up to 5 years. A two-sided log-rank test with an overall sample size of 2316 with a 10% dropout rate (1158 in ALND and 1158 in LAS group) achieves 80% power at a 0.05 significance level to detect a hazard ratio of 1.16 (upper limit of non-inferiority) when the proportion surviving in the control group is 0.71. An interim analysis will be carried out at 25% events and conditional power will be calculated. If the conditional power is below 20%, then the study will be discontinued for futility. The study has been approved by Institutional Ethics Committee (CTRI/2022/07/044461) Expected Study and Results- We started accrual in February 2023 and have screened 63 and randomized 45 patients until now. Ours is a first large randomised prospective study in the post-chemotherapy axillary management setting which will help us understand the efficacy of axillary conservation surgery in patients who are node negative post neoadjuvant chemotherapy. In future, lesser morbid procedures than LAS like targeted axillary dissection can be tested in the same trial. However, LAS as a technique of axillary conservation suits resource constraints and high volume setting such as ours. Citation Format: Shalaka Joshi, Jessicka Shah, Pallavi Daphale, Rohini Hawaldar, Anuradha Daptardar, Ayushi Sahay, Tanuja Shet, Palak Popat, Tabassum Wadasadawala, Nita Nair, Vani Parmar, Bipin Bandre, Shabina Siddique, Vaibhav Vanmali, Sudeep Gupta, Rajendra Badwe. An open label phase III randomized trial to evaluate the efficacy of Post-chemotherapy Axillary Conservation Surgery in breast cancer (PACS) [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 PO4-20-05.

Abstract PO4-13-11: Epigenetically defined sub-clonal heterogeneity drives therapy resistance in triple-negative breast cancer

Abstract Background Triple-negative breast cancer (TNBC) is a highly aggressive and heterogeneous disease with an average survival of less than 50%. Although immunotherapy is showing promising results in early TNBC, many patients do not respond, and chemotherapy remains the main treatment. High recurrence rates in TNBC are in part due to its inherent molecular heterogeneity and sub-clonal diversity, whereby cells present in minority sub-populations escape therapeutic pressure. Recurrent genomic alterations are not selected for upon therapy resistance in neoadjuvant chemotherapy (NAC) resistant TNBC, however sub-clonal transcriptionally defined cells are “primed” to drive resistance and are pre-existing, suggesting phenotypic heterogeneity is governed by inheritable activation of epigenetically defined regulatory regions. Here, we sought to characterise the sub-clonal and spatial diversity of chemotherapy resistant TNBC to identify the epigenetic hallmarks of lethal sub-populations of cells that may induce cell state transition, therapy resistance and ultimately metastatic progression. Methods Sixteen primary untreated triple-negative breast tumours (eight chemotherapy sensitive (ChemoS) and eight chemotherapy resistant (ChemoR, who died of their disease within three years)) were subjected to cell-matched high-depth multiome single nuclei RNA- and ATAC-sequencing. Driver DNA mutations and copy number alterations (CNA’s) were identified using a clinically validated targeted capture panel. Four tumours were subject to spatial RNA and ATAC profiling. Fourteen TNBC PDX models generated from patients with residual disease post NAC were subjected to single nuclei sequencing and used for validation. Meta-clustering of epithelial cells from the RNA profiles was used to identify sub-populations of cells harbouring distinct epigenetic and transcriptomic features enriched in ChemoR patients. Findings were validated in the BrighTNess TNBC NAC clinical trial and in chemotherapy treated TNBC patients from the SCAN-B study. Results Unsupervised meta-clustering (MC) of epithelial cells in G1 phase of the cell cycle identified nine meta-clusters across the dataset. A distinct immune-like MC was contributed by epithelial G1 cells, suggesting a cross-talk of epithelial cells with spatially proximal immune cells. Two MCs were dominated by cells from ChemoR patients and were defined by pathways related to hypoxia, EMT, and extra-cellular matrix signalling. Using scATAC profiles, we identified that the sub-populations of cells in the ChemoR dominant MCs were underpinned by both promoter and distal differential chromatin accessibility, that mapped to H3K27ac enhancer sites, suggesting a role of distal enhancer chromatin modification in regulating MC transcription. None of the meta-clusters were dominated by tumours with specific genetic mutations or CNA’s. Spatial ATAC and RNA profiling of a subset of tumours identified spatial epigenetically defined regions that showed distinct chromatin profiles, suggesting that the epigenetic regulation of genes that define the MCs are spatially distinct. ChemoR clusters were independently reproduced in a cohort of fourteen residual disease TNBC PDXs. Genes pertaining to the immune-like MC were associated with a good prognosis in independent cohorts of contemporary treated TNBC (SCAN-B) and associated with response to NAC in the BrighTNess trial. Marker genes from ChemoR dominant MCs were associated with poor prognosis and significant levels of residual disease following NAC. Conclusions Our multi-modal integrative analysis reveals unprecedented insight into the role of epigenetically defined spatially distinct, sub-clonal populations that pre-exist in treatment naïve TNBC and predict therapy response. This suggests pre-existing populations of cells have already acquired the epigenetic footprints and hence transcriptomic features to allow them to evade therapy. Citation Format: Fatemeh Ahmadimoghari, Yu Zhang, Ioanna Mavrommati, Shefali Thakur, Chris Starling, Ioannis Roxanis, Syed Haider, Rachael Natrajan. Epigenetically defined sub-clonal heterogeneity drives therapy resistance in triple-negative breast cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO4-13-11.

Abstract PO5-06-02: Phase II Trial of Combination of Atezolizumab, Cobimetinib and Eribulin (ACE) or Atezolizumab and Eribulin (AE) in patients with metastatic inflammatory breast cancer (IBC): Clinical data of both cohorts

Abstract Background: Metastatic IBC is an unmet clinical need due to the aggressiveness of this breast cancer subtype. Gene expression analysis of IBC samples post-neoadjuvant chemotherapy has revealed that dysregulation of immune pathways is common in tumors that do not have a complete pathologic response (pCR) to chemotherapy. The immune checkpoint PD-L1 is expressed in a third of IBC cases, and the MEK inhibitor, cobimetinib, has been shown to enhance the expression of PD-L1, the target of atezolizumab. Taken together, dual targeted therapy with atezolizumab and cobimetinib is hypothesized to be synergistic. Eribulin is a standard of care chemotherapy used in patients who have progressed on anthracycline-taxane based regimens. Materials and Methods: Patients received triple or double combination therapy depending on the timing of their enrollment. Patients with metastatic IBC who had measurable disease after at least 1 standard regimen were eligible. Any receptor subtype was allowed, and PD-L1 positivity was not required. The study began with a single cohort (n=17 patients) receiving all 3 agents with a lead-in phase to determine the MTD of cobimetinib in this setting. The study was later amended to include only atezolizumab and eribulin (cohort 2). Ten patients were treated in cohort 2. The study closed early due to lack of efficacy in cohort 2 and the changing landscape of metastatic breast cancer therapies. In cohort 1, atezolizumab was given every 2 weeks (840 mg), cobimetinib was given at 60/40/20 mg once daily, and eribulin was given at 1.4mg/m2 on day 1 and day 8 of 21-day cycles. In cohort 2, atezolizumab was given every 3 weeks (1200 mg) during the PD window and cycles 1-4, and then every 4 weeks (1680 mg) during maintenance, and eribulin was given at 1.4mg/m2 on day 1 and day 8 of 21-day cycles. Results: The MTD of cobimetinib was 40mg. In cohort 1, 17 patients were treated, 14 had at least 1 restaging evaluation. Seven patients had a partial response (50%) and 3 stable disease. The cohort was predominantly triple receptor-negative (n=13/17), with a median age of 51 yrs. The median PFS for patients in cohort 1 was 6.2 months (0-54.1). There were 2 exceptional responders, both with triple negative subtype, one of whom remains on therapy for &amp;gt;4.5 years without evidence of disease. The median overall survival was 29.6 months (2.9-133). The AE profile was largely expected, with 3 irAEs (1 grade 5 colitis, and 2 grade 2 pneumonitis), and one other patient with cardiac dysfunction requiring discontinuation of cobimetinib and atezolizumab. The MTD of cobimetinib was 40 mg. Cobimetinib-related toxicities were mild and largely gastrointestinal tract related. In cohort 2, only 1 patient experienced PR, and the median PFS was 3 months (1.2-6.2) and overall survival 8.3 months (1.8-19.9). One patient experienced autoimmune related hepatitis requiring discontinuation of protocol therapy. Due to excesive myelosuppression, dose of erublin was reduced to 1.1 mg per meter squared on day 1 and 8 and pegfilgastrim was added on day 9&amp;lt; Conclusions: The response profile of the triple combination demonstrated promise, and suggests that MEK inhibition may warrant further investigation as a strategy in metastatic IBC in a larger sample size. However, there does not appear to be synergy between atezolizumab and eribulin without the addition of targeted therapy. Citation Format: Angela Alexander, Hope Murphy, James Reuben, H. T. Carisa Le-Petross, Deanna Lane, Monica Huang, Savitri Krishnamurthy, Yun Gong, Dan Gombos, Nimisha Patel, Richard Allen, Suyu Liu, Anisha Patel, Andrew Futreal, Ignacio Wistuba, Rachel Layman, Naoto Ueno, Debu Tripathy, Bora Lim, Vicente Valero. Phase II Trial of Combination of Atezolizumab, Cobimetinib and Eribulin (ACE) or Atezolizumab and Eribulin (AE) in patients with metastatic inflammatory breast cancer (IBC): Clinical data of both cohorts [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO5-06-02.

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 PO3-23-01: Triple-tracer Technique for Sentinel Lymph Node Biopsy of Breast Cancer after neoadjuvant Chemotherapy using Blue-dye, Radioisotope combined with Real-time Indocyanine green(ICG) Fluorescence Imaging Procrdures

Abstract Background: For post-neoadjuvant chemotherapy (NAC) patients (pts) with BC, sentinel lymph node biopsy (SNB) was recommended using the dual-tracer mapping technique (radioisotope plus blue dye) or placing a biopsy clip into the positive node at diagnosis and identifying it at the time of surgery due to SN identification rates (IR) were lower and false negative rates (FNR) were greater for pts with local advanced breast cancer (BC) than those of pts with early stage BC in the absence of NAC. Our previous clinical trial has indicated that the real-time ICG fluorescence (RT-ICG) imaging technique could improve the diagnostic sensitivity and detection accuracy for SNB. Methods: Between April 2019 and May 2022, post-NAC SNB were successfully identified in 45 of 52 patients with stage ⅡA to ⅢB (T1-T3, N0-2, M0) who had histologically confirmed breast cancer selected to receive NAC and the standard surgeries were performed after finishing NAC. The SNs was detected by conventional procedures of blue-dye (Indigo carmine) plus 99mTc radioisotope (dual-tracer) and combined with concurrent RT-ICG technique. Clinical node positive (cN+) was diagnosed by the radiologists using axillary ultrasound, MRI and/or CT scan or assessed by fine needle aspiration cytology (FNAC). The positivity of each single SN by each single tracer (blue dye, ICG, or isotope alone) was counted and identified, respectively. All patients are required to undergo SNB followed by completion axillary lymph node dissection (CND). Then the IR and FNR of each single tracer and their summation (triple tracer) were calculated by comparing the results of the SNB and the histopathology of the resection specimens of CND. Results: Among 45 post-NAC pts, the IR and FNR of each single procedure for SNB was 45.7% and 55.6% when used Indigo Carmine blue, 70.3% and 11.1% when used RI, 82.6% and 0 when used ICG fluorescence, respectively. In contrast, the total calculation of triple tracer showed that IR reached to 100% and FNR was 0, respectively. The IR of triple tracer were 83.9% and 100% for ypN0 and ypN(+) pts after NAC, both FNR were 0%. Conclusion: Our results suggested that the triple tracer technique combining blue dye, ICG, and isotope is effective method for detection of SNs in post-neoadjuvant cN+ BC pts. The IR and FNR of SNB might be improved by this multiple tracer mapping technique, particularly for pts with ypN(+) after NAC. It is considered that the multi-tracer can complement each other for what was not able to be traced and detected by the single tracer with one mapping material, and that result in totally the improvement of identification rate of SNB. Citation Format: Hidetaka Watanabe, Yuko Takao, Yuriko Katagiri, Rie Sugihara, Uhi Toh. Triple-tracer Technique for Sentinel Lymph Node Biopsy of Breast Cancer after neoadjuvant Chemotherapy using Blue-dye, Radioisotope combined with Real-time Indocyanine green(ICG) Fluorescence Imaging Procrdures [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 PO3-23-01.

Abstract PO4-05-06: Hormone receptor-positive HER2-low metastatic breast cancer (mBC): evolution of HER2 status after CDK4/6 inhibitor treatment

Abstract Background Trastuzumab deruxtecan (T-DXd) is approved for HER2-low but not HER2-0 mBC. Therefore, identifying HER2-low status is of great clinical importance. Prior studies have shown HER2-low status is dynamic between primary tumor and metastatic relapse and between primary tumor and post-neoadjuvant chemotherapy residual tumor, and expert recommendations are to reiterate biopsies throughout the course of the disease. However, there is no data on when to repeat these biopsies. We provide here the first data on the evolution of HER2-low status in hormone receptor-positive (HR+) mBC before and after endocrine therapy (ET) in association with CDK4/6 inhibitor (CDK4/6i). Methods: Patients with pre-CDK4/6i+ET tumor biopsy were identified from a single large academic center database. Patients with unknown HER2 status were excluded. Pathological, clinical, and demographic data were extracted from clinical files. HER2-low was defined as HER2 IHC 1+, or 2+ with non-amplified HER2 by ISH, and HER2-0 by IHC score of 0+. Pathology central review for all paired pre- and post-treatment biopsies was performed by three expert breast cancer pathologists. Results: 304 consecutive patients with HR+/HER2- mBC treated with CDK4/6i+ET and who had immediate pre-treatment biopsy were included. Of these, 117 (38%) were HER2-0, and 187 (62%) were HER2-low. Clinical and demographic data did not differ between both groups. Patients received CDK4/6i+ET as first-line treatment in 48% of cases. Among this cohort, 49 patients had paired biopsies immediately after CDK4/6i+ET treatment. The discordance rate between pre- and post-CDK4/6i+ET HER2-status was 51% with 64% of HER2-0 patients becoming HER2-low and 38% of HER2-low switching to HER2-0. Among the 49 patients with paired biopsies, 43 had available material to perform a central pathology review. Of these, 22 (51%) were HER2-0, and 21 (49%) were HER2-low. Central pathology review showed a concordance level of 82% with pathology records, resulting in a modification of HER2 status in 7 HER2-0 patients as HER2-low, leading to a total of 65% of patient’s eligibility to T-DXd. Post-CDK4/6i+ET biopsy identified a switch to HER2-low in 10 additional HER2-0 patients resulting in a total of 38/43 (88%) candidates to T-DXd. No case became HER2 3+ after treatment. Neither baseline HER2 status, nor change in HER2 status after treatment affected the clinical outcome on CDK4/6i+ET (objective response, progression-free survival, overall survival). Conclusion: HER2-low status is dynamic, and 64% of mBC HER2-0 patients switched to HER2-low after a line of CDK4/6i+ET treatment. Since such a switch would guide post-progression treatment with T-DXd in patients initially not candidate, these results suggest that biopsy should be repeated early in the course of mBC to assess eligibility for T-DXd therapy. Our central pathology review of pre-treatment biopsies reclassified 24% of HER-0 patients as HER2-low, suggesting that pathology review is a legitimate first step before repeating biopsy or in the case of difficulty to re-biopsy. In our series, 88% of patients had a biopsy sample classified as HER2-low after pathological review of pre-treatment slides, followed by post-CDK4/6i+ET rebiopsy of HER2-0 cases. Citation Format: Alexandre de Nonneville, Pascal Finetti, Laurys Boudin, Lucas Usclade, Lenaïg Mescam, Emeline Durieux, Agathe Boucraut, Frederic Viret, Emilie Mamessier, Anthony Gonçalves, François Bertucci. Hormone receptor-positive HER2-low metastatic breast cancer (mBC): evolution of HER2 status after CDK4/6 inhibitor 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 PO4-05-06.

Sentinel Lymph Node Biopsy after Neoadjuvant Chemotherapy in Breast Cancer Patients with Positive Nodes Using Low-Cost Dual Dye Technique: Identifying Factors Associated with Adequate False Negative Rate Threshold

&lt;b&gt;&lt;i&gt;Background:&lt;/i&gt;&lt;/b&gt; In this study, we evaluated the feasibility of the sentinel lymph node (SLN) identification rate (SLN-IR) of fluorescein-guided sentinel lymph node biopsy (SLNB) in combination with methylene blue dye (MBD) and factors which can lead to a false negative rate (FNR) threshold of 10%. &lt;b&gt;&lt;i&gt;Methods:&lt;/i&gt;&lt;/b&gt; This was a prospective cross-sectional non-randomized validation study in patients with post-neoadjuvant chemotherapy (NACT) clinically node negative axilla who were node positive prior to start of NACT. Patients underwent validation of SLNB using fluorescein (and blue LED light) and MBD. Axillary dissection was performed irrespective of SLNB histology. SLIN-IR and FNR were assessed and compared with various molecular subtypes. &lt;b&gt;&lt;i&gt;Results:&lt;/i&gt;&lt;/b&gt; The SLNs were identified in 102 out of 120 (85%) post-NACT patients. The median number of sentinel lymph nodes identified was 2 (range 1–3). The SLN-IR using MBD was 85%, FD was 82.5%, and combined MBD FD was 85%. Two or more SLNs were removed in 72 patients and 11 patients had tumor in the rest of the axilla, resulting in an FNR of 17.4%. An FNR was 25% in case only one SLN was found, and it was 11.42% if two or more than two SLNs were excised. &lt;b&gt;&lt;i&gt;Conclusions:&lt;/i&gt;&lt;/b&gt; This cohort study found that use of low-cost dual dyes in patients with positive axillary disease, rendered cN0 with NACT, with 2 or more negative SLNs with SLNB alone, results in an FNR of 11.4%. Her 2 positive and TNBC with 2 or more negative SLNs are associated with an FNR of &amp;lt;10%. However, the number of such patients was small and further studies with larger sample size are warranted to confirm these findings.

Utility of CA-125 in interval surgery

Standard treatment for advanced-stage epithelial ovarian cancer (EOC) consists of debulking surgery and chemotherapy. Progression-free survival (PFS) and overall survival (OS) correlate with residual tumor burden after debulking surgery. There are situations in which it is not feasible to perform the aforementioned surgery, requiring neoadjuvant chemotherapy (NACT) with eventual interval surgery. The objective of the study was to retrospectively evaluate patients who were not plausible for primary cytoreduction, analyzing the value of CA-125 pre and post neoadjuvant chemotherapy and its suitability between these values and the surgical result.

Machine Learning-Based Prediction of Pathological Responses and Prognosis After Neoadjuvant Chemotherapy for Non–Small-Cell Lung Cancer: A Retrospective Study

BackgroundNeoadjuvant chemotherapy has variable efficacy in patients with non–small-cell lung cancer (NSCLC), yet reliable noninvasive predictive markers are lacking. This study aimed to develop a radiomics model predicting pathological complete response and postneoadjuvant chemotherapy survival in NSCLC. Materials and MethodsRetrospective data collection involved 130 patients with NSCLC who underwent neoadjuvant chemotherapy and surgery. Patients were randomly divided into training and independent testing sets. Nine radiomics features from prechemotherapy computed tomography (CT) images were extracted from intratumoral and peritumoral regions. An auto-encoder model was constructed, and its performance was evaluated. X-tile software classified patients into high and low-risk groups based on their predicted probabilities. survival of patients in different risk groups and the role of postoperative adjuvant chemotherapy were examined. ResultsThe model demonstrated area under the receiver operating characteristic (ROC) curve of 0.874 (training set) and 0.876 (testing set). The larger the area under curve (AUC), the better the model performance. Calibration curve and decision curve analysis indicated excellent model calibration (Hosmer–Lemeshow test, P = .763, the higher the P-value, the better the model fit) and potential clinical applicability. Survival analysis revealed significant differences in overall survival (P = .011) and disease-free survival (P = .017) between different risk groups. Adjuvant chemotherapy significantly improved survival in the low-risk group (P = .041) but not high-risk group (P = 0.56). ConclusionThis study represents the first successful prediction of pathological complete response achievement after neoadjuvant chemotherapy for NSCLC, as well as the patients’ survival, utilizing intratumoral and peritumoral radiomics features.

Evaluating persistent T1-weighted lesions without concurrent abnormal enhancement on breast MRI in neoadjuvant chemotherapy patients: implications for complete pathological response.

This study aims to determine whether persistent T1-weighted lesions signify a complete pathological response (pCR) in breast cancer patients treated with neoadjuvant chemotherapy and surgery, and to evaluate their correlation with imaging responses on MRI. A retrospective review was conducted on data from breast cancer patients treated between January 2011 and December 2018. Patients who underwent breast MRI and pre- and post-neoadjuvant chemotherapy followed by surgery were included. Those with distant metastasis, no planned surgery, pre-surgery radiation, ineligibility for neoadjuvant chemotherapy, or unavailable surgical pathology were excluded. Groups with and without persistent T1-weighted lesions were compared using the chi-square test for categorical variables and the Student t test or Wilcox rank sum test for continuous variables. Univariate logistic regression was used to evaluate the association of the final pathological response with the presence of T1-persistent lesion and other characteristics. Out of 319 patients, 294 met the inclusion criteria (breast cancer patients treated with neoadjuvant chemotherapy and subsequent surgery); 157 had persistent T1 lesions on post-chemotherapy MRI and 137 did not. A persistent T1 lesion indicated reduced likelihood of complete pathological response (14% vs. 39%, p < 0.001) and imaging response (69% vs. 93%, p < 0.001). Multivariable analysis confirmed these findings: OR 0.37 (95% CI 0.18-0.76), p = 0.007. No other characteristics correlated with T1 residual lesions. Persistent T1-weighted lesions without associated abnormal enhancement on post-treatment breast MRI correlate with lower complete pathological and imaging response rates. The study underscores the importance of persistent T1-weighted lesions on breast MRI as vital clinical markers, being inversely related to a complete pathological response following neoadjuvant chemotherapy; they should be a key factor in guiding post-neoadjuvant chemotherapy treatment decisions. • Persistent T1 lesions on post-chemotherapy breast MRI indicate a reduced likelihood of achieving a complete pathological response (14% vs. 39%, p < 0.001) and imaging response (69% vs. 93%, p < 0.001). • Through multivariable analysis, it was confirmed that the presence of a persistent T1 lesion on breast MRI post-chemotherapy is linked to a decreased likelihood of complete pathological response, with an odds ratio (OR) of 0.37 (95% CI 0.18-0.76; p = 0.007). • In addition to the convention of equating the absence of residual enhancement to complete imaging response, our results suggest that the presence or absence of residual T1 lesions should also be considered.

Oncological outcomes of post neo adjuvant chemotherapy breast conservation surgery in patients with locally advanced breast cancer

Abstract Introduction: Breast cancer in India is phenotypically different with locally advanced breast cancers (LABCs) forming 30–50% of all cases. Use of neoadjuvant chemotherapy (NACT), among other things has contributed to surgeons using breast conservation surgery (BCS) in very selected patients with good results. Herein, we describe the oncological outcomes of BCS in LABC patients undergoing surgery post NACT. Patients and Methods: This is an ambispective observational cohort study conducted between January 1996 and December 2019 after approval by Institute Ethics Committee, to study the ipsilateral breast tumor recurrence (IBTR) in patients with LABC undergoing BCS post NACT. The secondary objectives were to ascertain the disease-free survival (DFS) and overall survival (OS) and factors associated with IBTR in these patients. Patients were staged according to the anatomic American Joint Committee on Cancer (AJCC) VIII Tumor Node Metastasis (TNM) classification and clinic-demographic, pathologic, treatment, and follow-up details were noted. Results: Out of 822 patients with LABC, 71 patients undergoing BCS post NACT were included. Average tumor size at presentation was 6.43 cm. The most common T stage was T3 (57.7%) and N stage was N1 (53.5%). The most common stage group was IIIB in 40.8%. Around 75% received anthracycline-based NACT with 28.2% having a complete clinical response. A pathological complete response was seen in 16 patients (22.5%). The mean follow-up duration was 6.14 years. A total of 25 patients had recurrences: five patients had IBTR (7%) and four had a local with regional recurrence. Two, 5, and 10 years OS were 94.0, 83.8, and 61.9%, respectively, and DFS were 87.8, 67.1, and 50.6%, respectively. A higher clinical T stage was associated with poor DFS (p = 0.01). The risk of IBTR was not found to significantly correlate with any of the standard prognostic factors. Conclusion: BCS post NACT in suitably selected patients of LABC is a safe and viable option without adversely affecting oncological outcomes.

Abstract B060: Spatial landscape of cell cycle dynamics post-neoadjuvant chemotherapy in high-grade serous ovarian carcinoma

Abstract Introduction Neoadjuvant chemotherapy (NACT) has emerged as a well-established treatment modality for advanced-stage patients with high-grade serous carcinoma (HGSC). However, relapse and platinum resistance remain significant challenges, resulting in unfavorable long-term outcomes. The interplay between NACT and the tumor microenvironment (TME) is crucial for treatment response, yet its mechanisms are poorly understood. Methods We prospectively recruited &amp;gt;300 newly-diagnosed patients to the Oncosys-OVA study. We performed BRCA1/2 mutational profiling and genomic scarring (ovaHRDscar) to annotate the HGSCs to distinct genomic groups. Detailed surgical and clinical data were collected to assess NACT responses, while histological examination using H&amp;E staining annotated the morphological response patterns of HGSC. Tissue cyclic immunofluorescence (tCycIF) analysis was conducted on FFPE samples collected from the same cohort. We built and validated a tCycIF panel with antibodies targeting cell cycle-regulators and checkpoint inhibitors (Cyclin A, Cyclin D, p21, p27), proliferation (Ki-67, PCNA), and DNA damage markers (RAD51, γH2AX, p53), alongside other cell-type markers for tumor, stromal, lymphoid and myeloid populations. We used GeoMX spatial transcriptomics to capture spatially resolved and cell-population deconvoluted gene expression profiles within regions of interest from tCycIF spatial analyses. Results We employed tCycIF utilizing a validated custom-made antibody panel targeting up to 50 markers to characterize the cell populations in the TME, including their functional states, cell cycle profiles and DNA damage patterns. Via advanced image analysis, we revealed the spatial topographies of tumor-immune and stromal cells, cellular communities, and cell-cell interactions within the TME. Through the utilization of computational methods, we reconstructed the cell cycle dynamics and assessed the expression of markers in cells in pseudotime. Furthermore, by conducting a multivariate assessment of the proliferation markers, we were able to evaluate the spatial distribution of cells with distinct proliferative characteristics. To explore the transcriptome of these regions, we developed a pipeline that integrates tCycIF and GeoMx data, enabling the precise targeting of cell populations in adjacent slides. By examining the gene-expression signatures and enriched pathways within these regions, we uncovered molecular signatures associated with distinct morphological response patterns to NACT. These comprehensive analyses were integrated with the matching clinical, pathological, and genomic profiling information, leading to the identification of recurring cellular neighborhoods with potential therapeutic implications. Conclusions By integrating multi-omics and spatio-temporal analyses with clinicopathological features, we identified response-related patterns that could inform patient stratification and treatment selection. This study can potentially drive advancements in immuno-oncology and personalized therapeutic approaches for patients with HGSC. Citation Format: Ada Junquera, Zhihan Liang, Iga Niemiec, Inga-Maria Launonen, Mariana Luna-Alvarez, Matilda Salko, Maija Vääriskoski, Essi Kahelin, Ulla-Maija Haltia, Anni Virtanen, Anniina Färkkilä. Spatial landscape of cell cycle dynamics post-neoadjuvant chemotherapy in high-grade serous ovarian carcinoma [abstract]. In: Proceedings of the AACR Special Conference on Ovarian Cancer; 2023 Oct 5-7; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(5 Suppl_2):Abstract nr B060.

221 (PB-128) Poster - Comparative study of role of indocyanine green (ICG) combined with methylene blue dye versus methylene blue dye alone in sentinel lymph node biopsy (SLNB) in post-neo adjuvant chemotherapy breast cancer patients

221 (PB-128) Poster - Comparative study of role of indocyanine green (ICG) combined with methylene blue dye versus methylene blue dye alone in sentinel lymph node biopsy (SLNB) in post-neo adjuvant chemotherapy breast cancer patients

Treatment Response to Neoadjuvant Therapy in Squamous Esophageal Cancer-Correlation Between Metabolic Response and Histopathology.

Esophageal cancer is among the leading causes of cancer-related mortality worldwide. Patients presenting with localized and loco-regionally advanced cancer without distant metastases have reasonable survival with multimodality management. Adequate and comprehensive staging is the backbone for proper selection of patients fit for curative treatment. Positron emission tomography (PET) in combination with contrast-enhanced computed tomography (CECT) is utilized as the standard staging modality. Multimodality treatment has been able to achieve evaluable tumor responses including pathological complete response (pCR). It is, therefore, necessary to understand whether the impact of neoadjuvant therapy can be evaluated on imaging, i.e., standardized uptake value (SUV) on PET scan done for response assessment and if this can be correlated with histopathological response and later, with survival. Squamous cell carcinoma (SCC) is more common globally and in the Indian subcontinent; hence, we chose this subgroup to evaluate our hypothesis. This is a single institution, retrospective study. Out of the 1967 patients who were treated between 2009 and 2019, 1369 (78.54%) patients had SCC. Out of these, 44 received NACTRT, whereas 1325 received NACT followed by curative surgery. The standardized uptake value (SUV) of 18-fluorodeoxyglucose was recorded during pre- and post-neoadjuvant treatment (NAT) using positron emission tomography (PET). The histopathology of the final resection specimen was evaluated using the Mandard tumor regression grade (TRG) criteria with response being graded from 0 to 5 as no residual tumor (NRT), scanty residual tumor (SRT), and residual tumor We attempted to find a cut-off value of the post neoadjuvant SUV of the primary tumor site which correlated with achievement of better histopathological response. Out of 1325 patients of SCC esophagus who underwent surgery, 943 patients had available data of TRG, and it was categorized into the 0-2 category which had 325 patients (34.5%) and 3-5 category, 618 patients (65.5%). The SUV was taken only from the PET scans done at our institution, so as to achieve a more homogenous cohort, and this was available for 186 patients, 151 from the NACT group and 35 from the NACTRT group. The ROC method was used to find the cut-off for SUV (5.05) in the NACT cohort, which depicted significant difference in the outcome. Out of these, 93 patients who underwent NACT had SUV > 5.05 and 58 had SUV < 5.05. It was found that the subjective and objective histopathological scores correlated at a p value of < 0.0001. Specifically, the majority of cases with SRT tended to be in the 3-5 category of TRG, whereas cases with NRT are predominantly in the 0-2 category. In the ≥ 5.05 category of SUV, there were 76 cases with SRT. In the NACT cohort, the < 5.05 category of SUV, there are 26 cases with SRT and 32 cases with NRT. Among cases with SRT, 74.5% had SUV ≥ 5.05, while 25.5% had SUV < 5.05. Among cases with NRT, 34.7% had SUV ≥ 5.05, while 65.3% had SUV < 5.05 (p value 0.007). No significant association was found in the radio-pathological correlation in the NACTRT group. Our study confirms the correlation of post neoadjuvant chemotherapy PET SUV with histopathological response, the cut-off of SUV being 5.05 in our cohort. This confirms the predictive value of FDG PET as demonstrated in other studies. Furthermore, its prognostic value with respect to survival has been verified in multiple other studies. With larger scale randomized studies, we may be able to identify the group of patients who have borderline operability anatomically as well as physiologically, where alternative treatment regimens may be indicated to improve outcomes.

Comparison of PD-L1 (22C3) Expression in Paired Primary and Metastatic Breast Carcinoma

IntroductionPD-L1 immunohistochemistry (IHC) is being used as a predictive marker of the benefit derived from immunotherapy in several cancer types, including breast cancer. However, the insight gleaned of the prognostic and predictive value of PD-L1 status and its correlation with molecular characteristics during breast cancer progression remains limited. MethodsWe performed an PD-L1 (22C3) assay in pre-treatment primary and metastatic tumor sections from 33 patients with breast carcinoma, matched for post neoadjuvant chemotherapy (p-NACT). PD-L1 expression was evaluated using 3 scoring methods: immune cell (IC) and tumor cell (TC) with a 1% as the cutoff value, and combined positive scores (CPS) with a 1 as the cutoff value. Twenty-two samples from 11 patients had successful fluorescence in situ hybridization (FISH)-based molecular data available for analysis. ResultsIn the 33 pre-treatment primary tumors, PD-L1 IC, TC, and CPS showed positive correlation with stromal tumor infiltrate lymphocytes (sTIL), histological grade 3, and triple negative breast carcinoma (TNBC). In the matched metastatic tumors, only PD-L1 IC showed a positive correlation with sTIL. The primary tumors showed a higher PD-L1 expression than the matched metastatic tumors by IC and CPS. Negative to positive conversion by CPS was identified in the metastatic tumors from lung, pleura and liver. p-NACT tumors also showed a trend of lower PD-L1 expression compared to the pre-treatment tumors. Six patients had matched samples for molecular and PD-L1 comparison, and none of them showed consistent gene alterations or PD-L1 expression among the primary, p-NACT and metastatic tumors. ConclusionOur study showed a decrease in PD-L1 expression and disconnected molecular features during breast cancer progression. Repeating PD-L1 IHC testing could be considered in some specific metastatic sites if primary tumors were negative. Further studies are needed to identify other predictive factors for immune checkpoint inhibitor (ICI) therapy in patients with breast carcinoma.

Neoadjuvant chemotherapy-induced remodeling of human hormonal receptor-positive breast cancer revealed by single-cell RNA sequencing

Hormone receptor-positive breast cancer (HR+ BC) is known to be relatively insensitive to chemotherapy, and since chemotherapy has remained the major neoadjuvant therapy for HR+ BC, the undetermined mechanism of chemoresistance and how chemotherapy reshapes the immune microenvironment need to be explored by high-throughput technology. By using single-cell RNA sequencing and multiplexed immunofluorescence staining analysis of HR+ BC samples (paired pre- and post-neoadjuvant chemotherapy (NAC)), the levels of previously unrecognized immune cell subsets, including CD8+ T cells with pronounced expression of T-cell development (LMNA) and cytotoxicity (FGFBP2) markers, CD4+ T cells characterized by proliferation marker (ATP1B3) expression and macrophages characterized by CD52 expression, were found to be increased post-NAC, which were predictive of chemosensitivity and their antitumor function was also validated with in vitro experiments. In terms of immune checkpoint expression of CD8+ T cells, we found their changes were inconsistent post-NAC, that LAG3, VSIR were decreased, and PDCD1, HAVCR2, CTLA4, KLRC1 and BTLA were increased. In addition, we have identified novel genomic and transcriptional patterns of chemoresistant cancer cells, both innate and acquired, and have confirmed their prognostic value with TCGA cohorts. By shedding light on the ecosystem of HR+ BC reshaped by chemotherapy, our results uncover valuable candidates for predicting chemosensitivity and overcoming chemoresistance in HR+ BC.