Advanced Breast Cancer Patients Research Articles

Prognostic significance of HER2-low status in HR-positive/HER2-negative advanced breast cancer treated with CDK4/6 inhibitors

Whether Human Epidermal growth factor Receptor 2 (HER2)-low status has prognostic significance in HR + /HER2- advanced Breast Cancer (aBC) patients treated with first-line Endocrine Therapy plus CDK 4/6 inhibitors remains unclear. In 428 patients evaluated, HER2-low status was independently associated with significantly worse PFS and OS when compared with HER2-0 status. Based on our findings, HER2-low status could become a new prognostic biomarker in this clinical setting.

Abstract 1049: Liquid biopsy-based comprehensive genomic profiling reveal mutational landscape in advanced breast cancer

Abstract Introduction: Breast cancer is the most common malignancy worldwide in females, with more than 2.26 million new cases and 680 thousand of deaths in 2020. Advanced breast cancer is characterized by complicated genomic landscape and requires comprehensive genomic profiling. However, tissue biopsy is hard to get in patients with recurrent metastasis. Meanwhile, limited studies have been reported to use liquid biopsy and were not capable of reporting gene copy number loss. Here we reported a comprehensive genomic profiling study in advanced breast cancer patients using liquid biopsy. Methods: The prospective study is part of the Predicine’s Phoenix Program, a global molecular biomarkers screening program in multiple solid tumors. Currently, the study enrolled 220 advanced breast cancer patients from 8 centers in China, who were naïve to the 1st line treatment. 10ml of blood was collected from each patient and delivered to a central lab for ctDNA analysis. The study applied PredicineCARE, an NGS-based liquid biopsy assay, to profile somatic mutations, copy number variations, and gene fusions among these patients. Results: The study identified 793 somatic mutations and 283 copy number variants among blood samples from 220 patients. The most common altered genes were TP53(101/220, 46%), PIK3CA(77/220, 35%), BRCA2(37/352, 17%), PTEN(26/220, 12%), and ATM(24/220, 11%). Gene copy number gain incidents were identified on MYC(n=28), AKT3(n=23), FGFR1(n=18), and PIK3CA(n=16), etc. The study also reported gene copy number loss incidents through liquid biopsy, such as CDKN2A(n=17), BRCA1(n=12), TP53(n=11), RB1(n=11), BRCA2(n=10), PTEN(n=9), and ATM(n=8). Conclusions: This study revealed the comprehensive mutational landscape of advanced breast cancer patients through liquid biopsy, providing novel biomarkers for clinical diagnosis and targeted therapy mechanism studies. Citation Format: Haoran Tang, Feng Xie, Yue Zhang, Shidong Jia. Liquid biopsy-based comprehensive genomic profiling reveal mutational landscape in advanced breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1049.

Abstract 5590: Liquid biopsy testing in metastatic or advanced breast cancer patients during the COVID-19 pandemic

Abstract Objective: During the COVID-19 pandemic, cancer patients had restricted access to standard of care tissue biopsy. Liquid biopsy assays using next generation sequencing technology provides a less invasive method for determining circulating tumour mutations (ctDNA) associated with targeted treatments or prognosis. As part of deploying technology to help cancer patients obtain molecular testing, a clinical program was initiated to offer liquid biopsy testing for Canadian patients with advanced or metastatic breast cancer. Methods: Blood was drawn in two 10 mL StreckTM DNA BCTs and sent to the CAP/CLIA/DAP accredited Imagia Canexia Health laboratory for testing using the clinically validated Follow ItTM liquid biopsy assay. Plasma was isolated using a double spin protocol and plasma cell-free DNA (cfDNA) extracted using an optimized Promega Maxwell RSC method. Extracted cfDNA was amplified using the multiplex amplicon-based hotspot 30 or 38 gene panel and sequenced. An in-house developed bioinformatics pipeline and reporting platform were used to identify pathogenic single nucleotide variants (SNVs), indels (insertions and deletions), and gene amplification. Included in the panel are genes associated with metastatic breast cancer: AKT1, BRAF, ERBB2, ESR1, KRAS, PIK3CA, TP53. Results: To identify biomarkers, 1214 metastatic or advanced breast cancer patient cfDNA samples were tested. There were 15 cases sent for repeat testing. We reported 48% of samples harboring pathogenic ctDNA mutations in TP53 (22%), PIK3CA (19%), ESR1 (18%), AKT1 (2%), ERBB2 (1.5%). Co-occurring variants were identified in samples with ESR1/PIK3CA as well as TP53/PIK3CA (both p-values <0.001). Interestingly, 29% of samples with mutated ESR1 harbored ≥ 2 ESR1 ctDNA mutations. In 56% of cases, previous molecular testing indicated the cancer subtype as hormone receptor (ER, PR) positive with/without HER2 negative status. In this specific subgroup, 49% harbored ctDNA mutations with 63% of those being PIK3CA and/or ESR1 mutations. Conclusions: A population of Canadian women with metastatic breast cancer were tested using a liquid biopsy gene panel during the COVID-19 pandemic for identification of biomarkers for targeted therapeutic options. Over 50% of the samples were identified as hormone positive, with greater than 60% harboring PIK3CA and ESR1 ctDNA mutations. Studies have shown that metastatic PIK3CA mutated ER-positive/HER2-negative tumors are predictive to respond to alpelisib therapy and have FDA and Health Canada approval. Additionally, ESR1 mutations are associated with acquired resistance to antiestrogen therapies, and interestingly we identified 29% of ESR1 mutated samples with multiple mutations possibly indicating resistance subclones. In future studies, longitudinal monitoring for presence of multiple targetable and resistance mutations could be utilized to predict or improve clinical management. Citation Format: Benjamin L. Furman, Ebru Baran, Sonal Brahmbhatt, Betty Chan, Ka Mun Nip, Adrian Kense, Brenda Murphy, Vincent Funari, David G. Huntsman, Ruth Miller, Melissa K. McConechy. Liquid biopsy testing in metastatic or advanced breast cancer patients during the COVID-19 pandemic. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5590.

Abstract 4444: Targeting PI3K isoforms to improve the effectiveness of T cell mediated immunotherapy

Abstract Hyperactivation of the PI3K pathway has been reported to correlate with resistance to immune checkpoint blockade therapy (ICB) in melanoma, highlighting the therapeutic potential of combining PI3K inhibition (PI3Ki) with ICB. To maximize the clinical benefit of PI3Ki-based immune oncology (IO) combination, we characterized the role of PI3K isoforms in tumor and T cells and determined the immunological impacts of PI3Ki alone or in combination with ICB. Inhibitions of PI3K were achieved by either genetic knockdown (KD) or the bioactive compound in PTEN-present (B16/MC38), PTEN-absent (BP/D4M) tumor cell lines, and CD8+ T cells (Pmel-1). Following PI3Ki, we determined the activation status of the PI3K pathway (p-AKT level), transcriptional profile, and cellular function of these cells. We found both in vitro KD and pharmacological inhibition of either PI3Kα or PI3Kβ displayed a dramatic reduction of the PI3K pathway in tumor cells but moderate or no reduction in T cells, whereas the PI3K pathway significantly decreased in T cells with PI3Kγ or PI3Kδ inhibition. KD of PI3Kα or β isoforms drastically sensitized both D4M and MC38 tumors to αPD1 in vivo. We also observed that only PI3Kγ or PI3Kδ inhibition profoundly suppressed cytokine production and cytotoxicity of CD8+ T cell, suggesting that PI3Kα or PI3Kβ isoform inhibition can achieve tumor specific PI3Ki with limited impacts on T cell function. Furthermore, we used multiple syngeneic melanoma models to determine whether PI3K isoform inhibition can synergize the antitumor activity of ICB in vivo. In PTEN-present tumors, BYL719 (BYL, a PI3Kα inhibitor) synergized with αPD1 to delay tumor growth and extend survival (median survival of MC38-bearing mice in control (Ctrl), BYL, αPD1, and combination (Comb) groups: 30, 36, 33, and >45 respectively; p<0.05: Ctrl/BYL/αPD1 vs Comb). However, a limited combinatorial effect between GSK2636771(a PI3Kβ inhibitor) and αPD1 was observed in PTEN-present tumor models. Moreover, the combination of BYL and αPD1 exhibits superior antitumor activity in a spontaneous Braf-mutant, PTEN-loss melanoma model when compared with either reagent. Mechanistically, the combination of BYL and αPD1 improved CD8+ T cells tumor infiltration (14 days treatment, mean CD8+ number/mg of the tumor, Ctrl:1392.9, BYL:2073.9, αPD1:1545.2, Comb:4691.8; p<0.01: Ctrl/BYL/αPD1 vs Comb) and reduced MDSCs in MC38 tumors (p<0.05: Ctrl vs Comb). Multi-omics profiling of tumor cells with in vitro and in vivo PI3K isoform inhibition is ongoing. Collectively, our results demonstrate that PI3Kα inhibitor can potentiate T cell-mediated antitumor immune responses regardless of PTEN status, providing a strong rationale for the clinical development of the BYL-based IO combination. In collaboration with Novartis, MD Anderson Cancer Center will launch a Phase I/II trial of the FDA-approved BYL in combination with αPD1 in advanced melanoma and breast cancer patients. Citation Format: Ritu Bohat, Xiaofang Liang, Chunyu Xu, Yitao Tang, Jiakai Hou, Nicholas A. Egan, Leilei Shi, Ashley Guerrero, Roshni Jaffery, Elizabeth M. Burton, Han Liang, Hussein Tawbi, Michael A. Davies, Weiyi Peng. Targeting PI3K isoforms to improve the effectiveness of T cell mediated immunotherapy. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4444.

Abstract 3123: A method for quantifying circulating tumor DNA level and molecular response using methylome sequencing

Abstract Background: Circulating tumor DNA (ctDNA) level and the change in level at a subsequent time point (e.g. on-treatment change from baseline or postoperative changes through time) are promising tools for predicting patient prognosis and response to therapy. Existing methods use somatic variant allele frequencies to quantify circulating tumor fractions (cTF). Their performance can be limited by the number of detectable somatic alterations and the associated limit of detection (LoD), as well as interference from copy number variation and non-tumor alterations, such as clonal hematopoiesis. Here, we describe the LoD, precision and limit of quantitation (LoQ) of cTF level and change using GuardantINFINITY, a next generation sequencing panel covering over 800 genes with genome-wide methylation detection. Method: The cTF of a single sample is estimated from methylation signals across targeted regions of the GuardantINFINITY methylation panel, calibrated using internal training data. cTF change compares two or more samples from the same patient to identify patient-specific methylated regions, and compare the methylation signals of the paired regions. LoQ of cTF level and change were assessed in experimental titrations of advanced colorectal, breast, and lung cancer patient samples and cell line samples into cancer-free backgrounds at different target levels between 0.1%-0.5% cTF. LoD is defined as the lowest cTF level where >95% replicates were detected to have tumor-derived methylation signals. LoQ of cTF level or change is defined as the lowest cTF where the coefficient of variation (CV) across replicates is less than 30%. Accuracy of methylation based cTF compared to cTFs calculated from maximum VAF of somatic mutations was assessed on 1,400 clinical samples of colorectal and lung cancer patients (N=189, 372, 252 and 463 for stage I to IV). Results: Experimental titrations of cancer samples demonstrated a single-sample LoD of 0.05% cTF (lowest dilution level) and quantitative precision down to a LoQ of below 0.1%, compared to the LoQ of 0.3% estimated by somatic mutations. In paired clinical titration samples, the LoQ of methylation ctDNA level change was also below 0.1%, compared to the LoQ of ctDNA level change estimated by somatic mutations at 0.3-0.5%. In the 1,400 clinical samples, 64% had at least one somatic mutation detected, 90% had ct-DNA detected with methylation and 96% of these ct-DNA detected samples had cTF above the defined methylation LoQ. Among patients with both methylation and genomic signals identified, the methylation method quantified a similar cTF to those that were calculated using maximum somatic driver mutations (Pearson r=0.83). Conclusion: Methylome sequencing using GuardantINFINITY enables accurate and precise quantification of ctDNA level and change with a liquid-only approach, offering longitudinal ctDNA monitoring for more patients than previous methods. Citation Format: Sai Chen, Katie Quinn, Che-Yu Lee, Jun Zhao, Kyle Chang, Tingting Jiang, Shile Zhang, Carin Espenschied, Sara Wienke, Thereasa Rich, Indira Wu, Yvonne Kim, Xianxian Liu, Nageswara Alla, Dustin Ma, Giao Tran, Han-Yu Chuang. A method for quantifying circulating tumor DNA level and molecular response using methylome sequencing [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3123.

Tumour necrosis factor-alpha levels as predictor factor on clinical response of anthracycline-based neoadjuvant chemotherapy in locally advance breast cancer patients: experimental research.

Analysing TNF-α levels as a predictor factor on clinical response anthracycline-based neoadjuvant chemotherapy. This study design used observational analysis. The length of study was carried out in the period from May 2021 to June 2022. The study procedure included measuring participants' TNF-α levels the day before chemotherapy was carried out and clinical response. Participants received anthracycline-based neoadjuvant chemotherapy (cyclophosphamide of 500mg/m2, doxorubicin of 50mg/m2 and fluorouracil/5FU of 500mg/m2) for 3 cycles. The study analysis used the Chi-square, logistic regression and Spearman's test with P<0.05. The average TNF-α levels was 137.2±311.8pg/ml, ranging from 5.74 to 1.733pg/ml. The results of the calculation of the cutoff value of TNF-α in the study were 18635pg/ml (area under curve =0.850; 95% CI =0.729-0.971). Based on cutoff 1, most participants with high TNF-α levels also had a negative response of 83.3% and those with low TNF-α levels also had a positive response of 75% (P<0.001). Meanwhile, at cutoff 2, similar conditions were also found, namely high TNF-α levels, negative response (84.2%) and low TNF-α levels, positive response (78.9%; P<0.001). The statical analysis showed a significant association of TNF-α levels on the clinical response of chemotherapy, which showed r=-0.606 and P<0.001. TNF-α levels predict clinical response for anthracycline-based neoadjuvant chemotherapy in locally advanced breast cancer patients.

Surgical Outcome after Downstaging in Locally Advanced Breast Carcinoma-A Clinical Study of 50 Cases

Background: The number of deaths related to breast cancer is increasing at an alarming pace worldwide. In Bangladesh, the incidence rate of breast cancer was about 22.5 per 100000 females. Almost everyone has a palpable lump, and 40% of them have locally advanced breast cancer. The typical treatment for patients with LABC is neoadjuvant chemotherapy followed by surgery. Materials and Methods: From January 2018 to December 2022, 50 newly diagnosed locally advanced breast cancer (LABC) patients were enrolled in this prospective study at the Bangladesh Medical College Hospital, Dhaka; to assess the clinical and pathological response of the disease after chemotherapy and surgery. The size of the primary tumor and the size of the axillary nodes were measured and compared to the previous record. The patients had a surgery and axillary excision after three to six weeks of neoadjuvant treatment. The pathological response of the primary tumor and axillary node was examined using histopathology. Other biological markers were tested, including the estrogen receptor (ER), progesterone receptor (PR) and Human epidermal growth factor receptor (Her-2). Results: 44 patients (88.0%) responded clinically after four cycles of neoadjuvant chemotherapy, with 7 patients (14.0%) showing complete clinical response (cCR) and 41 patients (82.0%) showing partial response (pCR). In 22 individuals, surgical specimens revealed complete pathological response (cPR) (10 percent). Conclusions: The neoadjuvant chemotherapy schedule for locally advanced breast cancer has good surgical outcome. KYAMC Journal Vol. 13, No. 04, January 2023: 229-233

Profiling the Spectrum of Headache Disorders on 440 Breast Cancer Patients: Highlights on Clinical and Pathological Mechanisms.

Although widely studied, the association between migraines (M) and breast cancer (BC) risk remains evasive. In this prospective single-center study, 440 early or locally advanced BC patients were enrolled at IRCCS Humanitas Research Hospital. Clinical and demographical data were collected. Those who suffered from headaches were evaluated with the International Classification of Headache Disorders. M was found to be significantly more prevalent in BC patients: 56.1% versus an expected prevalence of 17% in the global population. M patients showed a higher risk of having stage II or III BC than stage I, which was more frequently found in the non-headache population. Interestingly, the frequency of headache attacks was positively correlated with estrogen (r = 0.11, p = 0.05) and progesterone (r = 0.15, p = 0.007) expression, especially in patients with migraine without aura. The higher the expression of hormone receptors in BC, the higher the headache frequency. Moreover, patients suffering from headaches showed an overall earlier onset of BC. Our findings challenge the idea of a net preventive role of M on BC, suggesting a rather complex interaction in which M mostly influences some BC subtypes and vice versa. Further multi-center studies with extended follow-up are needed.

Establishment and verification of a digital PCR assay for the detection of CK19 expression in quantitative analysis of circulating tumor cell.

The objective of this study was to establish and verify a digital PCR assay for the detection of CK19 gene expression, and to use it to detect circulating tumor cells (CTC) by taking advantages of its ultra-high sensitivity and absolute quantitation. Firstly, the primers and probes were designed according to the mRNA sequence of CK19 gene, and housekeeping gene ABL1 was used as the internal control. The best candidate was screened by human breast cancer MCF7 cells and healthy human leukocytes from 13 sets of primer and probes and verified by direct sequencing. Secondly, after the reaction conditions of the selected primers and probes were optimized, limit of blank (LOB) analysis were performed with different concentrations of cDNAs as templates from healthy human leukocytes. The results revealed the LOB of CK19 with ABL1 copy numbers of 20,000, 15,000, 10,000, 5000 and 2500 were 9.24, 8.93, 3.12, 3.17 and 2.53 copies, respectively. Thirdly, the different concentrations of cDNAs from MCF7 cells and healthy human leukocytes were premixed and used in the limit of detection (LOD) analysis, which showed that the CK19 gene could be effectively detected at the concentration ratio of 50%, 10%, 5%, 1%, 0.5% and 0.1%, and the linear R2 value was 0.9998. Finally, the preliminary results of digital PCR in clinical samples indicated that CK19 copy numbers were higher in advanced breast cancer patients than healthy controls. The above results demonstrated the advantages of our CK19 digital PCR assay in sensitivity, specificity, and accurate quantification. If verified further, the assay is expected to play significant roles in the quantitative analysis of CTC in breast cancer with a good application prospect.

The role of HMGCR expression in combination therapy of simvastatin and FAC treated locally advanced breast cancer patients.

Several studies have shown the role of statin added to the patient's chemotherapy regimen and the role of Hydroxymethylglutaryl-CoA Reductase (HMGCR) expression in predicting breast cancer patient outcomes. In our previous study, adding statins improved clinical and pathological responses in LABC patients. Furthermore, we planned to study statin's role as a combination to neoadjuvant chemotherapy (NAC) in treating locally advanced breast cancers on the basis of HMGCR expression. Moreover, we aimed to study the association between the patients' clinicopathological characteristics and HMGCR expression. This study is a randomized, double-blinded, placebo-controlled trial in two health centers in Indonesia. Each patient enrolled with written informed consent and then randomized to receive either simvastatin 40 mg/day or a placebo, combined with the fluorouracil, adriamycin, and cyclophosphamide (FAC) NAC. HMGCR was associated with low staging and normal serum cholesterol in the high Ki67 level group (p =0.042 and p =0.021, respectively). The pre-and post-chemotherapy tumor sizes are significantly correlated in two groups (HMGCR negative expression, p =0.000 and HMGCR moderate expression, p =0.001) with a more considerable average decrease in tumor size compared to HMGCR strong expression group. Statin therapy might work better in HMGCR-negative or low-expression tumors, although HGMCR expression is associated with better clinical parameters in our study.

Cytotoxic chemotherapy is associated with decreased bone mineral density in postmenopausal women with early and locally advanced breast cancer.

The burden and mechanisms of endocrine therapy-related bone loss have been studied in detail. However, there is limited data regarding cytotoxic chemotherapy's impact on bone health. There are no definitive guidelines for bone mineral density (BMD) monitoring and treatment with bone-modifying agents during cytotoxic chemotherapy. The study's primary objective was to evaluate the changes in BMD and fracture risk assessment tool (FRAX) scores among breast cancer women on cytotoxic chemotherapy. One hundred and nine newly diagnosed early and locally advanced postmenopausal breast cancer patients planned for anthracycline and taxane-based chemotherapy were recruited prospectively during the study period from July 2018 to December 2021. BMD of the lumbar spine, the femoral neck, and the total hip were assessed by dual-energy X-ray absorptiometry scan. BMD and FRAX scores were evaluated at baseline, end of chemotherapy, and 6months of follow-up. The median age of the study population was 53 (45-65) years. Early and locally advanced breast cancers were seen in 34 (31.2%) and 75 (68.8%) patients, respectively. The duration of follow-up between two BMD measurements was 6months. The percentage of decrease in BMD at the lumbar spine, femoral neck, and total hip were - 2.36 ± 2.90, - 2.63 ± 3.79, and - 2.08 ± 2.80, respectively (P-value = 0.0001). The median risk of major osteoporotic fracture (MOF) at 10years (FRAX score) increased from 1.7 (1.4) to 2.7% (2.4) (P-value = 0.0001). This prospective study in postmenopausal breast cancer women shows a significant association of cytotoxic chemotherapy with the worsening of bone health in terms of BMD and FRAX score.

WGCNA-based identification of potential targets and pathways in response to treatment in locally advanced breast cancer patients.

Locally advanced breast cancer patients have a poor prognosis; however, the relationship between potential targets and the response to treatment is still unclear. The gene expression profiles of breast cancer patients with stages from IIB to IIIC were downloaded from The Cancer Genome Atlas. We applied weighted gene co-expression network analysis and differentially expressed gene analysis to identify the primary genes involved in treatment response. The disease-free survival between low- and high-expression groups was analyzed using Kaplan-Meier analysis. Gene set enrichment analysis was applied to identify hub genes-related pathways. Additionally, the CIBERSORT algorithm was employed to evaluate the correlation between the hub gene expression and immune cell types. A total of 16 genes were identified to be related to radiotherapy response, and low expression of SVOPL, EDAR, GSTA1, and ABCA13 was associated with poor overall survival and progression-free survival in breast cancer cases. Correlation analysis revealed that the four genes negatively related to some specific immune cell types. The four genes were downregulated in H group compared with the L group. Four hub genes associated with the immune cell infiltration of breast cancer were identified; these genes might be used as a promising biomarker to test the treatment in breast cancer patients.

A retrospective, non-interventional study of breast cancer patients diagnosed with ER+/HER2 negative, locally advanced or metastatic breast cancer treated with palbociclib in Denmark

BackgroundThe recommended first-line treatment for advanced, ER+/HER2 negative breast cancer is a CDK 4/6 inhibitor in combination with an endocrine backbone. This study investigated the use of palbociclib, as first- or second-line therapy for advanced breast cancer patients in a real-world setting.Material and MethodsThis retrospective, population-based study included all Danish, advanced breast cancer patients with ER+/HER2 negative disease who initiated first- or second-line treatment with palbociclib from January 1st, 2017, until December 31st, 2020. The primary outcomes were PFS and OS.ResultsThe study included 1054 advanced breast cancer patients with a mean age of 66.8 years. Median OS was 51.7 months (95% CI, 44.9–54.6) for all patients in the first-line setting (n = 728) and median PFS was 24.3 months (95% CI, 21.7–27.8). Patients treated in second line (n = 326) had a median OS of 32.5 months (95% CI, 29.9–35.9) and a median PFS of 13.6 months (95% CI, 11.5–15.7). In first-line setting, the PFS and OS were significantly different for endocrine sensitive patients treated with AI (aromatase inhibitor) (n = 423) vs. fulvestrant (n = 158) as endocrine backbone to palbociclib (median PFS AI 31.3 months vs fulvestrant 19.9 months, p = 0.002 and median OS AI 56.9 months vs. fulvestrant 43.6 months, p = 0.001). In endocrine resistant patients (n = 145), no statistically significant difference in PFS was shown (median PFS AI 21.5 months vs. fulvestrant 12.0 months, p = 0.09), whereas OS was significantly different (median OS AI 43.5 months vs. fulvestrant 28.8 months, p = 0.02).ConclusionIn this real-world study, treatment with palbociclib combination therapy met the standards of efficacy set by the phase III trials, PALOMA-2 and PALOMA-3, and the standards set by real-world studies in other countries. The study showed significantly different outcomes in terms of PFS and OS in endocrine sensitive patients comparing AI vs. fulvestrant as endocrine backbone to palbociclib as first-line therapy.

Efficacy of CDK 4/6 Inhibitors and Radiotherapy in Breast Cancer Patients with Brain Metastases

Cyclin-dependent kinase 4/6 inhibitors (CDK4/6i) combined with endocrine therapy are the standard of care for HR-positive/HER2-negative advanced breast cancer patients. However, their role in the treatment of brain metastases is currently unclear. We retrospectively evaluate the results of patients (pts) with advanced breast cancer treated at our institution with CDK4/6i and radiotherapy to the brain. The primary endpoint was progression-free survival (PFS). Secondary endpoints were local control (LC) and severe toxicity. Among 371 pts treated with CDK4/6i, 24 pts (6.5%) received radiotherapy to the brain before (11 pts), during (6 pts), or after (7 pts) CDK4/6i treatment. Sixteen pts received ribociclib, six received palbociclib, and two received abemaciclib. Six- and twelve-month PFS was 76.5% (95% CI: 60.3-96.9) and 49.7% (95% CI: 31.7-77.9), respectively, whereas six- and twelve-month LC was 80.2% (95% CI: 58.7-100) and 68.8% (95% CI: 44.5-100), respectively. With a median follow-up of 9.5 months, no unexpected toxicity was observed. We conclude that treatment with both CDK4/6i and brain radiotherapy is feasible and should not increase the toxicity compared to brain radiotherapy or CDK4/6i alone. However, the small number of individuals treated concurrently limits the conclusions about the combination of both modalities, and the results from ongoing prospective clinical trials are eagerly awaited to understand both the toxicity profile and the clinical response fully.

Abstract P5-02-35: Radiomic biomarkers to predict the efficacy of anti-PD-1 immunotherapy-based combinational treatment in advanced breast cancer: a multi-center study

Abstract Introduction: Immunotherapy, especially immune checkpoint inhibitors, is regarded as one of the major breakthroughs in breast cancer treatment. However, it is an important challenge to accurately locate the patients who benefit from immunotherapy, because there is still a lack of universal and robust predictors of the efficacy of immunotherapy. Radiomics can extract quantitative imaging features in a highthroughput manner and assess tumor microenvironment and heterogeneity. This study investigated the correlation between deep learning radiomic biomarkers, including its predictive value for immunotherapy response in advanced breast cancer (ABC) patients. Methods: 240 patients with metastatic breast cancer treated with anti-PD-1 immunotherapy in three institutions from February 2018 to January 2022 were studied retrospectively, among which, the data of 61 patients were collected through prospective clinical trials. For these data, 189 ABC patients from prospective clinical trials and Sun Yat-sen University Cancer Center were evaluated as a training set to establish a radiomic model to predict value of immunotherapy, then this model was independently validated with 51 ABC patients from Sun Yat-sen Memorial Hospital. The CE-CT (contrast enhanced computed tomography) images of patients within one month before immunotherapy were were delineated with regions of interest (ROI) and radiomics features extraction. Data dimension reduction, feature selection and radiomic model construction were carried out with multilayer perceptron (MLP) deep learning. Combined with the radiomics signatures, independent clinical characteristics and pathological risk factors, the predictive model was established by multivariable logistic regression analysis. ROC curve (receiver operator area under receiver operator area, AUC) and Delong test were used to evaluate and compare the prediction performance of the model. Finally, decision curve analysis (DCA) is used to determine the net benefits predicted by the model. Results: The radiomic biomarker performed well in predicting response to immunotherapy, reflflected by the AUCs in the training set(AUC=0.885, 95% CI: 0.829-0.941) and validation set (AUC=0.871, 95% CI: 0.752-0.991), respectively. The accuracy of this radiomics model was better than those of clinical indicators, including PD-L1 expression. Conclusions: By combining deep learning technology and CT images and PD-L1 expression, we developed an independent predictive model that could identify MBC patients most likely to benefifit from immunotherapy, and may effectively improve more precise and individualized decision support. Citation Format: Jieqiong Liu, Jianli Zhao, Zhixian Sun, Yunfang Yu, Zhongyu Yuan, Herui Yao, Ying Wang. Radiomic biomarkers to predict the efficacy of anti-PD-1 immunotherapy-based combinational treatment in advanced breast cancer: a multi-center study [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P5-02-35.

Abstract P5-03-04: PIK3CA mutation prevalence in hormone receptor positive breast cancer patients in United Arab Emirates

Abstract Background: The Phosphatidylinositol-4,5-bisphosphonate 3-kinase catalytic subunit alpha (PIK3CA) gene is mutated in about 30-40% of hormone receptor positive/human epidermal growth factor receptor 2 negative (HR+/HER2−) breast cancer (BC) patients. For HR+/HER2- advanced breast cancer patients with disease progression following endocrine-based therapy, the NCCN guideline recommends testing for PIK3CA mutations with tumour or liquid biopsy to identify suitable patients for targeted therapy with alpelisib, an oral α-specific PI3K inhibitor in combination with fulvestrant. The primary objective of this study was to evaluate the proportion and distribution of PIK3CA mutational landscape of HR+ve BC patients at the largest cancer centre in the United Arab Emirates (UAE). Material and methods: Retrospective review of consecutive HR+ve BC patients at Tawam Hospital for whom PIK3CA testing was requested. DNA was extracted from the samples and a targeted resequencing assay was used for mutation detection in exons 7, 9 and 20 of the PIK3CA gene. Sequencing was carried out using the Next Generation Sequencing platform Ion GeneStudio S5 Prime System with a detection limit of 2-5% of the mutant allelic content. Results: 124 patients with HR+ve BC were enrolled in the present study. The pathology samples were considered unsuitable/unsatisfactory in 18 cases. The median age was 51.5 years (range 31-90). All patients were female, 54% were post-menopausal and 49% presented with de-novo metastatic disease. Of the 106 eligible patients, PIK3CA mutations were detected in 33 (31%) patients, the most common being H1047R (45%) and E545K (30%) mutations in exons 20 and 9, respectively. Other less common mutations included C420R mutations (6%) in exon 7, E542 (6%) in exon 9 and H1047Y (3%) in exon 20. 9% of patients had more than one hotspot mutations, primarily in exons 9 and 20. Of the 12 HER2 +ve patients tested, 3 had PIK3CA mutations, most commonly the H1047R mutation in exon 20. Conclusion: The prevalence of PIK3CA mutations and the presence of most common hotspot mutations in exons 20 and 9 was consistent with prior published studies. The clinical relevance of PIK3CA mutations in HER2 +ve BC patients needs further assessment. Citation Format: Fathi Azribi, Mohammad Hourani, Sulaman Magdub, Aydah Alawadhi, Ali Yousif, Emad Dawoud, Khaled Al Qawasmeh, Mouza Al Ameri, Diaeddine Trad, Nouri Bennini, Mohamed Ahmed, Jawaher Ansari. PIK3CA mutation prevalence in hormone receptor positive breast cancer patients in United Arab Emirates [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P5-03-04.

Abstract P3-02-07: Combined Chemo-endocrine Therapy Maybe a New Option for HR+/HER2− Advanced Breast Cancer: A Prospective, Single-center Clinical Study of Fulvestrant plus Oral Vinorelbine

Abstract Background Fulvestrant have demonstrated synergistic antitumor effect with chemotherapy regimen. This study evaluates the efficacy and safety of Fulvestrant with Vinorelbine in patients with hormone receptor positive (HR+)/human epidermal growth factor receptor-2-negative (HER2−) recurrent or metastatic breast cancer. Methods In this prospective, single-arm and investigator-initiated clinical study, patients with recurrent or metastatic HR+/HER2− breast cancer after the first line adjuvant endocrine therapy for &amp;gt; 1 year were eligible, in which the subjects of the first line was defined as the patients with recurrence and metastasis after adjuvant endocrine therapy for over 1 year and did not receive treatment for the recurrence and metastasis and the second-line defined as the patients who had disease progression after receiving first-line endocrine therapy or first-line chemotherapy). Patients were administered i.m. Fulvestrant 500mg (day 1 per cycle for 28 days) and oral Vinorelbine (60 mg/m2 on day 1, 8 and 15 of each cycle). The primary endpoint was progression-free survival (PFS). Secondary endpoints included overall survival (OS), objective response rate (ORR), disease control rate (DCR), duration of response (DoR), and safety. The Kaplan–Meier method and log-rank test were used to evaluate PFS and OS. Results Total 38 HR+/HER2- advanced breast cancer patients with median follow-up time (25.1 months) were enrolled in, and median PFS [9.86 months (95% CI: 7.2, 23.13)] were discovered. The median PFS of the first-line and the second-line treatment population were 20.73 months (95% CI: 9.82, NR) and 4.27 months (95% CI: 3.68, NR), respectively. The median OS of the intent-to-treat (ITT) and the first-line treatment population were not reached, and the OS of the second-line treatment was 28.2 months (95% CI: 11.5, NR). The ORR of the ITT population was 39.47% (95% CI: 23.93, 55.01). The ORR of the patients receiving first-line and second-line treatments were 44.44% (95% CI: 25.70, 63.19) and 27.27% (95% CI: 0.95, 53.59), respectively. The DCR of ITT population was 92.11% (95% CI: 83.54, 100.00)], and the median DoR was approximately 15.33 months (95% CI: 7.23, 22.54)]. In the safety analysis, most of the adverse events were grade of 1/2, and none of grade 4/5 adverse events were reported. Conclusion This is the first exploratory study of Fulvestrant with oral Vinorelbine regimen in the treatment of HR+/HER2− recurrent and metastatic breast cancer conducted worldwide. The combinative chemo-endocrine therapy was efficacious, safe and promising for patients with HR+/HER2− advanced breast cancer. Citation Format: Xue Wang, Jian Yue, Jiayu Wang, Pin Zhang, Fei Ma, Binghe Xu, Peng Yuan. Combined Chemo-endocrine Therapy Maybe a New Option for HR+/HER2− Advanced Breast Cancer: A Prospective, Single-center Clinical Study of Fulvestrant plus Oral Vinorelbine [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P3-02-07.

Abstract OT1-01-02: EMBER-4: A phase 3 adjuvant trial of imlunestrant vs standard endocrine therapy (ET) in patients with ER+, HER2- early breast cancer (EBC) with an increased risk of recurrence who have previously received 2 to 5 years of adjuvant ET

Abstract Background: Adjuvant ET has been the standard of care for patients with estrogen receptor-positive (ER+), human epidermal growth factor receptor 2-negative (HER2-) EBC. A significant proportion of patients with increased risk still experience disease relapse despite available ET and more optimum ET is needed to prevent patients developing incurable metastatic cancer. Distant recurrence risk ranges from 20% to 40% after 5 years of adjuvant ET, depending on clinicopathological (clin-path) features at diagnosis. Consequently, there is a need to further optimize adjuvant treatment, particularly in those patients who are at increased risk of recurrence. Imlunestrant is an orally bioavailable selective estrogen receptor degrader (SERD) with pure antagonistic properties and the potential to overcome ET resistance. In early phase trials, imlunestrant monotherapy showed favorable safety with pharmacokinetic (PK) exposures exceeding fulvestrant and preliminary efficacy in ER+, HER2- advanced breast cancer patients (EMBER, Jhaveri 2022) along with robust biological/pharmacodynamic activity and tolerability in EBC (EMBER-2, Neven). Trial Design: EMBER-4 is a randomized, open-label, global phase 3 study comparing imlunestrant versus physicians’ choice of ET, in patients who are at an increased risk of recurrence based on clin-path features and who have received 2 to 5 years of standard adjuvant ET. Approximately 6,000 patients will be randomized 1:1 to receive imlunestrant (400 mg daily) for 5 years or physicians’ choice of adjuvant ET (tamoxifen or an aromatase inhibitor, AI, dosed per label). Study treatment duration is 5 years. Males and pre-/peri-menopausal women will receive concomitant treatment with a GnRH agonist if receiving imlunestrant or an AI. Stratification factors include time from initial adjuvant ET, use of prior adjuvant cyclin dependent kinase 4/6 inhibitors, nodal status, menopausal status, and geographic region. Eligibility criteria: Eligible patients are adult males and females (pre-, peri- or postmenopausal) with ER+, HER2- EBC who have completed definitive locoregional therapy and have received 2 to 5 years of prior adjuvant ET without disease recurrence, but who are at increased risk of recurrence based on clin-path features at diagnosis. Prior (neo) adjuvant chemotherapy and/or targeted therapy with a CDK4/6- or PARP- inhibitor is permitted. Study endpoints: The primary endpoint is invasive disease-free survival (IDFS), excluding second non-breast primary invasive cancers. Key secondary endpoints include distant relapse-free survival, overall survival, IDFS including second non-breast primary invasive cancers, safety, PK and patient reported outcomes. Recruitment for EMBER-4 begins globally in Q4 2022. Citation Format: Komal Jhaveri, Joyce O’Shaughnessy, Fabrice Andre, Matthew P. Goetz, Nadia Harbeck, Miguel Martín, Francois-Clement Bidard, Zachary M. Thomas, Suzanne Young, Roohi Ismail-Khan, Lillian M. Smyth, Michael Gnant. EMBER-4: A phase 3 adjuvant trial of imlunestrant vs standard endocrine therapy (ET) in patients with ER+, HER2- early breast cancer (EBC) with an increased risk of recurrence who have previously received 2 to 5 years of adjuvant ET [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr OT1-01-02.

Abstract P2-11-19: Inflammatory indexes as prognostic biomarkers in advanced triple negative breast cancer patients

Abstract Background The identification of treatment selection biomarkers for advanced triple negative breast cancer (aTNBC) patients remains an unmet need. The immune system is known to be involved in the microenvironment of triple negative breast cancer (TNBC). Immune ratios like the neutrophil-to-lymphocyte ratio (NLR), the platelet-to-lymphocyte ratio (PLR), the monocyte-lymphocyte ratio (MLR) and the systemic immune-inflammation index (SII) may reflect the immune system functional status in these patients and the involvement of circulating immune cells in cancer progression. In particular MLR showed to predict overall survival (OS) in aTNBC and to contribute to migration of circulating tumor cells [1]. Methods A retrospective-prospective, observational multicenter study from the GIM-14 experience was performed to investigate the association between inflammatory indexes (NLR, MLR, PLR and SII), as measured at baseline and at progression, and clinical and survival aspects in patients with aTNBC in first line setting. The optimal cutoff values between low and high expression of inflammatory indexes were established on the basis of cut-off values determined in a previously conducted study in order to validate them[1], and was used to predict progression-free survival (PFS) and OS. Time-to-event variables (PFS; OS) were calculated using Kaplan-Meier method, while Cox regression model was used to estimate HRs and their 95% CI. Results 105 consecutive patients with a diagnosis of aTNBC were fully evaluated for the final analysis. The median age at diagnosis was 55 years (33-86). Of them, 80 patients received a neo/adjuvant treatment after diagnosis. At first progression the majority of patients (n= 97) received chemotherapy, while only 8 patients were treated with chemo-immunotherapy due to the programmed death ligand 1 (PD-L1) expression in the immunohistochemical analyses. At a median follow-up of 54 months, median PFS in the whole patients population was 13 months (95% CI 9,4-16,5), while median OS was 17.3 OS (95% CI 13-22,2). All high inflammation based scores evaluated at diagnosis of metastatic disease were significantly associated with lower PFS, in particular high NLR (≥3) and high MLR (≥0.34) (p = 0.0006 and p = 0.011, respectively). Similarly, all high indexes appeared significantly associated with a lower OS, especially NLR (&amp;gt;3), SII (≥836) and MLR (≥0.34) (p &amp;lt; 0.0001, p = 0.0005, p=001 respectively). In particular also NLR and SII evaluated at disease progression after first line treatment were significantly associated with a worse OS (p=0.0006 and p=0.001 respectively). In multivariable analysis for predictors of overall survival, the number of metastatic sites, NLR, SII and MLR remained significant (p&amp;lt; 0.0001, p=0.006, p=0.005 respectively). Conclusions NLR, SII and MLR are predictors of OS in aTNBC. Although our results need validation with larger studies, we suggest that inflammatory ratios could be used as feasible biomarkers of prognosis and treatment efficacy in aTNBC. Further research about HER-2 low categorized patients will be updated and presented at the final meeting. 1. De Giorgi U, Mego M, Scarpi E, Giordano A, Giuliano M, Valero V, Alvarez RH, Ueno NT, Cristofanilli M, Reuben JM. Association between circulating tumor cells and peripheral blood monocytes in metastatic breast cancer. Ther Adv Med Oncol. 2019 Aug 14;11:1758835919866065. doi: 10.1177/1758835919866065. PMID: 31452692; PMCID: PMC6696837. Citation Format: Caterina Gianni, Michela Palleschi, Emanuela Scarpi, Filippo Merloni, Eva Blondeaux, Fabio Puglisi, Elena Collovà, Palma Pugliese, Francesco Cognetti, Irene Giannubilo, Tommaso Ruelle, Claudia Bighin, Lucia Del Mastro, Ugo De Giorgi. Inflammatory indexes as prognostic biomarkers in advanced triple negative breast cancer patients [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P2-11-19.

Abstract P4-07-45: Treatment strategies for advanced triple negative breast cancer patients as per routine clinical practice: analysis from the observational study GEICAM/2014-03 (RegistEM)

Abstract Background: Triple negative breast cancer (TNBC) is well known for its more aggressive course and poorer prognosis compared to other BC subtypes. RegistEM study provides real world data to understand the distribution of BC subtypes in the advanced setting, being its primary objective. Biological samples collection is part of its procedures. This is a non-interventional cohort study and 1,907 patients (pts) have been enrolled up to now (females and males) with advanced BC (ABC), diagnosed from Jan-2016 to Dec-2019, either after recurrence or as first BC diagnosis, in 38 Spanish sites. These pts will be followed for at least 5 years. Methods: In the current analysis (cut-off date 08/April/2022, database ongoing), we describe characteristics, treatment patterns and outcomes, including comparison between recurrent and de novo disease, of 157 pts with advanced TNBC included in the RegistEM study. Those pts represent the 10% of pts available in the database at the cut-off date and with ABC diagnosis up to December 2018 (n=1559). The BC clinical subtypes were histologically confirmed on the most recent tumor lesion (metastatic [M] or primary BC) before starting with the 1st-line therapy. Results: At first ABC diagnosis, 73% pts had recurrent early BC (EBC), 26% de novo MBC and 1% unresectable locally ABC (ULABC). Median age was 57 years (range 30-88), all pts were women, 98% Caucasian and 65% postmenopausal. Family history of BC and/or ovarian cancer was reported in 37% pts, and a hereditary-risk genetic test was performed in 59 of 147 pts. Germline BRCA1/2 and TP53 were the most frequently mutated genes, 21% (6/28) and 47% (8/17) pts, respectively. Visceral involvement was present in 69% pts (similar between recurrent EBC and de novo ABC, although brain metastases were only present in the recurrent EBC group), and ≤ 2 metastatic locations in 59%. In 61% (70/115) pts with recurrent EBC, the subtype was assessed in metastatic lesions, and 39 pts of them also had TN subtype in primary BC. In terms of the most frequent therapies by line: 1) 1st-line: chemotherapy (CT) (60%) and CT/biological therapy (BT) (39%). Of the 87 pts with CT alone, monotherapy was the preferred option in 57% pts (capecitabine 25%, taxanes 16%, and eribulin or vinorelbine, 5% each). Bevacizumab was the most frequent BT (79%) combined with CT (single agent in 56% pts, mostly taxanes and capecitabine). Progressive disease (PD) was reported in 85% pts (similar in pts with both recurrent and de novo MBC or ULABC); 2) 2nd-line: CT (79%) (monotherapy capecitabine, eribulin, taxanes) and CT/BT (17%) (CT-containing bevacizumab 82%). Progression was reported in 92% pts; 3) 3rd-line: CT (90%) (eribulin 33%, platinum-based 25%) and CT/BT (9%) (CT-containing bevacizumab 67%). Progression was reported in 88% pts. At database cut-off date, death was reported in 133 (85%) pts, mainly because of PD. Overall survival (OS) was similar between both groups, recurrent and de novo MBC. Conclusion: In this population of Spanish TNBC pts with ABC, three quarters had recurrent disease. De novo ABC pts had a higher proportion of non-visceral metastases, with absence of brain involvement at the first diagnosis. Single-agent CT and CT plus bevacizumab were the most frequent therapies, and OS was similar between recurrent and de novo MBC pts, although numerically higher in the later group. Citation Format: Silvia Antolin Novoa, César A Rodríguez, Josefina Cruz, Sara López-Tarruella, Ariadna Tibau, Encarna Adrover, Ana Miguel, Mireia Margelí, Purificación Martínez, María Hernández, Antonio Antón, Álvaro Rodríguez-Lescure, Catalina Falo, Isabel Álvarez, Diego Malón, Raquel Andrés, José L Alonso-Romero, César Gómez, J. José Illaramendi, Ruth Campo, Juan José Miralles, Susana Bezares, Federico Rojo, Angel Guerrero-Zotano. Treatment strategies for advanced triple negative breast cancer patients as per routine clinical practice: analysis from the observational study GEICAM/2014-03 (RegistEM) [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P4-07-45.