Ve Breast Cancer Research Articles

A molecular switch from tumor suppressor to oncogene in ER+ve breast cancer: Role of androgen receptor, JAK-STAT, and lineage plasticity

Cancers develop resistance to inhibitors of oncogenes mainly due to target-centric mechanisms such as mutations and splicing. While inhibitors or antagonists force targets to unnatural conformation contributing to protein instability and resistance, activating tumor suppressors may maintain the protein in an agonistic conformation to elicit sustainable growth inhibition. Due to the lack of tumor suppressor agonists, this hypothesis and the mechanisms underlying resistance are not understood. In estrogen receptor (ER)-positive breast cancer (BC), androgen receptor (AR) is a druggable tumor suppressor offering a promising avenue for this investigation. Spatial genomics suggests that the molecular portrait of AR-expressing BC cells in tumor microenvironment corresponds to better overall patient survival, clinically confirming AR's role as a tumor suppressor. Ligand activation of AR in ER-positive BC xenografts reprograms cistromes, inhibits oncogenic pathways, and promotes cellular elasticity toward a more differentiated state. Sustained AR activation results in cistrome rearrangement toward transcription factor PROP paired-like homeobox 1, transformation of AR into oncogene, and activation of the Janus kinase/signal transducer (JAK/STAT) pathway, all culminating in lineage plasticity to an aggressive resistant subtype. While the molecular profile of AR agonist-sensitive tumors corresponds to better patient survival, the profile represented in the resistant phenotype corresponds to shorter survival. Inhibition of activated oncogenes in resistant tumors reduces growth and resensitizes them to AR agonists. These findings indicate that persistent activation of a context-dependent tumor suppressor may lead to resistance through lineage plasticity-driven tumor metamorphosis. Our work provides a framework to explore the above phenomenon across multiple cancer types and underscores the importance of factoring sensitization of tumor suppressor targets while developing agonist-like drugs.

Abstract PO2-04-14: Dual Inhibition of WEE1 and PKMYT1 Synergistically Overcomes CDK4/6 Inhibitor Resistance in Breast Cancer

Abstract Cyclin-dependent kinase 4/6 inhibitors (CDK4/6i) are approved for the treatment of advanced estrogen receptor-positive, HER2-negative (ER+ve) breast cancer when combined with endocrine therapy. However, the emergence of resistance to CDK4/6 inhibitors poses a significant clinical challenge. This study investigates the mechanisms underlying CDK4/6 inhibitor resistance and identifies a common occurrence of high replication stress in triple-negative breast cancer (TNBC) and CDK4/6 inhibitor-resistant ER+ve breast cancers. While ER+ve breast cancer patients have benefited from targeted therapy, TNBC patients, particularly those without germline BRCA1/2 or PALB2 mutations, lack effective treatment options. TNBC and CDK4/6 inhibitor-resistant ER+ve breast cancer cells exhibit an increased dependence on cell cycle arrest to repair replication stress-induced DNA damage. Failure to exit the cell cycle results in excessive DNA damage, thereby limiting their proliferative potential. Based on these findings, we hypothesize that dual inhibition of WEE1 and PKMYT1, two kinases involved in G2/M cell cycle transition and crucial for cell cycle arrest and DNA damage repair, could synergistically inhibit tumor growth. Although WEE1 and PKMYT1 share a common function in promoting G2/M cell cycle transition through CDK1 phosphorylation, their functions are not entirely redundant, suggesting that targeting both kinases may elicit a synergistic response. Recent clinical trials have shown resistance to WEE1-targeted monotherapies, emphasizing the need for combining WEE1 inhibitors with other agents, such as PKMYT1 inhibitors. We demonstrate the synergistic effects of WEE1 inhibitor (MK1775/AZD1775) and PKMYT1 inhibitor (RP6306) in a panel of TNBC and ER+ve breast cancer cells with acquired palbociclib resistance (PalboR). Combination treatment with both inhibitors leads to excessive unrepaired DNA damage, as indicated by increased γH2AX foci following 48 hours of combination treatment, whereas single-agent treatments induce significantly lower levels of DNA damage. Furthermore, we observed the AZD1775/RP6306 combination decreases the expression of the DNA repair protein Rad51 in PalboR cells. To evaluate the clinical potential of dual WEE1 and PKMYT1 inhibition, we generated organoids from metastatic breast cancer lesions of patients who had progressed on CDK4/6 inhibitors for ex vivo studies. Our results demonstrate that dual inhibition of WEE1 and PKMYT1 is more effective than single-agent treatments in eliminating CDK4/6 inhibitor-resistant organoids. Additionally, using patient-derived xenograft mouse models from patients who had progressed on palbociclib and endocrine treatment, we show that the AZD1775/RP6306 combination exhibits superior tumor suppression effects compared to single agents. Overall, this study highlights the potential therapeutic benefits of dual inhibition of WEE1 and PKMYT1 in overcoming CDK4/6 inhibitor resistance in TNBC and ER+ve breast cancer patients. These findings provide a rationale for future clinical trials aimed at exploring the clinical utility of this combination therapy. Citation Format: Mei-Kuang Chen, Grace DeAlessandro, Tuyen Bui, Khandan Keyomarsi. Dual Inhibition of WEE1 and PKMYT1 Synergistically Overcomes CDK4/6 Inhibitor Resistance in Breast Cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO2-04-14.

Abstract PO3-11-01: Single centre experience of the adoption of self-administered HER2-directed therapy in patients with breast cancer

Abstract Single centre experience of the adoption of self-administered HER2-directed therapy in patients with breast cancer Background: Programs to promote the self-administration of systemic anti-cancer therapy (SACT) offer greater convenience and shared decision making for patients with the opportunity to alleviate pressures on cancer services. Aims and Objective: The aims of this study were to quantify the uptake/acceptability of self-administration (SA) of subcutaneous trastuzumab (sc T), to evaluate safety, patients’ perception of the programme and the chair capacity released as a consequence. Methods: Patients receiving T for the treatment of HER2 +ve breast cancer were offered training in SA. The competency-based training programme, under the supervision of a chemotherapy-trained nurse, consisted of a minimum of 3 training sessions. Patients were also provided with printed and electronic material (via an App) on how to self-administer sc T, with 24/7 contact details in the event of an adverse event or device failure. Once trained and deemed competent, sc T was shipped to the patients’ home in a temperature-controlled environment, in a pre-filled syringe. All patients were assessed by telephone one day before and one day after SA using the Common Terminology Criteria for Adverse Events (CTCAE). Analysis of the total number of administrations of sc T, between February 2022 and June 2023 was conducted. A telephone survey using a validated questionnaire Self-Management Assessment scale (SMASc) was also undertaken. Results Of 46 breast cancer patients receiving single agent sc T, 32 agreed to participate in the program and were trained. 2 patients were undergoing training at data analysis. 6 patients declined and 6 were ineligible for the programme on the basis of inclusion criteria. The median age of the 32 patients that participated was 62, (range 27-77). The average distance from their home address to the cancer centre was 11.7 miles (range 3.5-27.9). 25 (78%) patients were Caucasian, 4 (13%) were Asian and 3 (9%) were of African/Caribbean origin. Patients had received an average of 10 sc injections in the hospital environment (median 5, range 1-103) before starting the training sessions. They required an average of 3 training sessions before sign-off (median 3, range 1-4). In the 32 patients studied, a total of 302 SA injections were delivered median 9 (range 1- 24) No Grade 3 or 4 CTCAE toxicities or infusion-related reactions were reported. During the 17-month period, a total of 302 hours of chair time was saved. 25 of the 32 patients responded to SMASc questionnaires utilising the six-point Likert scale. Patients reported average scores of 5.32 (median 6) and 5.56 (median 6) respectively, for questions relating to having information about their condition and sufficient training to self-administer. They felt that they had sufficient support to participate in the programme (average 5.56 median 6). 80% of the patients would recommend this programme and 88% felt they had benefited. Comments from patients themed around the value of the support provided, ease of administration and time saved. Discussion Programs such as these empower patients and carers to take a more active role in managing their condition with consequent reduced hospital attendance. Safety and acceptability for those patients who agreed to the program has been confirmed. Success of this program with sc T has enabled expansion to incorporate self-administration of Phesgo (sc trastuzumab and pertuzumab) with 31% (14/45) of the current P patient cohort enrolled onto the programme within 2 weeks of roll out and the first patients self-administering their treatment from August 2023. With the continued expansion of SACT treatments, we encourage stakeholders to consider self-administration of SACT as an option. Formulation of treatments conducive to patient self-administration is a key component to this. Citation Format: Wendy Ng, Vikash Dodhia, Amy Guppy, Stephanie Sutherland, Marlgozata Wojtas, Karen Harrold, Adisa Aolat, Tome Tapiwa, David Miles. Single centre experience of the adoption of self-administered HER2-directed therapy in patients with 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 PO3-11-01.

Neoadjuvant chemotherapy for triple-negative and Her2 +ve breast cancer: striving for the standard of care.

Neoadjuvant chemotherapy (NAC) for triple-negative (TN) and Her2-positive (HER2) breast cancers is supported by international guidelines as it can decrease extent of surgery, provide prognostic information, and allow response-driven adjuvant therapies. Our goal was to describe practice patterns for patients with TN and HER2-positive breast cancer and identify the factors associated with the receipt of NAC versus surgery as initial treatment. A retrospective population-based cohort study of adult women diagnosed with stage I-III TN or HER2-positive breast cancer (2012-2020) in Ontario was completed using linked administrative datasets. The primary outcome was NAC as first treatment. The association between NAC and patient, tumor, and practice-related factors was examined using multivariable logistic regression models. Of 14,653 patients included, 23.9% (n = 3500) underwent NAC as first treatment. Patients who underwent NAC were more likely to be younger and have larger tumors, node-positive disease, and stage 3 disease. Of patients who underwent surgery first, 8.8% were seen by a medical oncologist prior to surgery. On multivariable analysis, increasing tumor size (T2 vs T1/T0: 2.75 (2.31-3.28)) and node-positive (N1 vs N0: OR 3.54 (2.92-4.30)) disease were both associated increased odds of receiving NAC. A considerable proportion of patients with TN and HER2-positive breast cancer do not receive NAC as first treatment. Of those, most were not assessed by both a surgeon and medical oncologist prior to initiating therapy. This points toward potential gaps in multidisciplinary assessment and disparities in receipt of guideline-concordant care.

Abstract 3370: Anti-tumor activity of Debio 0123 in combination with sacituzumab govitecan in preclinical models of breast cancer

Abstract Background: Debio 0123 is a WEE1 inhibitor that has previously shown significant preclinical efficacy in combination with DNA damaging agents and is currently being investigated in phase 1 clinical studies either as a monotherapy or in combination with different standard therapies. Sacituzumab govitecan (SG) is a TROP2 directed antibody-drug-conjugate (ADC) carrying an SN38 payload that has recently gained approval in TNBC and ER+ve breast cancer after demonstrating improvements in survival versus standard therapies. Despite these promising data some patients still do not respond to SG treatment, develop resistance or experience toxic side effects. Herein we present preclinical data that demonstrates Debio 0123 improves tumor response to SG in breast cancer models and provides sustained complete responses and anti-metastatic activity. Methods: Synergy between Debio 0123 and SG was evaluated in breast cancer cell lines, with varying levels of TROP2 expression, in vitro using standard cytotoxicity assay in a matrix combination format. Efficacy of Debio 0123 and SG as monotherapies or in combination was further assessed in vivo, in both TROP2high and TROP2low subcutaneous breast cancer xenograft models at different doses. Results: In vitro, Debio 0123 in combination with SG demonstrated synergistic tumor cell killing in all 4 breast cancer cell lines tested, at all concentrations. In vivo, TROP2high MDA-MB-468 breast cancer xenograft tumors treated with Debio 0123 at 30mg/kg QD resulted in minimal anti-tumor activity as a monotherapy but completely regressed 100% of the tumors in combination with SG. Furthermore, 40% of these complete regressions were sustained for up to 100 days post-treatment initiation. These data were then further replicated at a reduced dose of SG. In the TROP2low MDA-MB-231luc model, Debio 0123 significantly improved response to SG resulting in a 2-fold improvement in tumor growth inhibition. Additionally, combination treatment significantly inhibited metastasis of these tumors to the lung and lymph nodes as monitored by bioluminescence. Collectively, these results lead to a significant improvement in animal survival as a combination compared to either treatment as a monotherapy. Conclusion: These results demonstrate that Debio 0123 synergizes with, and significantly improves breast cancer tumor cell response to, SG regardless of TROP2 expression levels (both in vitro and in vivo), leading to complete regressions and inhibition of metastasis. Collectively these data support Debio 0123 in combination with SG could be a potential therapeutic approach for improving responses in patients with breast cancer. Citation Format: Luke Piggott, Esteban Rodrigo Imedio, Francesco Staehli. Anti-tumor activity of Debio 0123 in combination with sacituzumab govitecan in preclinical models of breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3370.

SIRT1 mediates breast cancer development and tumorigenesis controlled by estrogen-related receptor β.

Silent mating type information regulation 2 homolog 1 (SIRT1) is a class III histone deacetylase (HDAC) that is NAD + dependent and essential for metabolism, senescence, and cell survival. SIRT1 is overexpressed in several cancers, including breast cancer. SIRT1 is a well-known target gene of the estrogen receptor alpha (ER alpha) and is closely related to ER alpha deacetylation. Transcription factor Estrogen-related receptors (ERRs) share sequence homology with ERs in the DNA-binding domain, therefore, the possibility of sharing target genes between them is high. Our current research aims togain insight into the function of ERRβ in regulating the activity of SIRT1 during the progression of breast cancer. ER-positive (ER + ve) breast cancer cells and tissues had considerably enhanced SIRT1 expression. Six potential ERRE sites were identified by analysis of the 5' upstream region of SIRT1, and both in vitro and in vivo experiments supported their presence. We found SIRT1 to be up-regulated in ERRβ overexpressed ER + ve breast cancer cells. Furthermore, our findings suggested that ectopic production of ERR and PCAF would increase SIRT1 activity. Our findings also indicated that ectopic production of ERRβ and PCAF increased SIRT1 activity. With sufficient evidence demonstrating the substantial involvement of SIRT1 in cell proliferation, migration, and colony formation capability, we were also able to illustrate the tumorigenic role of SIRT1. Overall, our findings highlight SIRT1's tumorigenic influence on breast cancer and suggest that SIRT1 inhibitors might serve as potential therapeutic drugs for the treatment of breast cancer.

Palbociclib real-world data collection to assess safety and efficacy in patients with metastatic HER2+ve breast cancer

Palbociclib real-world data collection to assess safety and efficacy in patients with metastatic HER2+ve breast cancer

Overexpression of BQ323636.1 contributes to anastrozole resistance in AR+ve/ER+ve breast cancer.

Aromatase inhibitors (Ais) are used as adjuvant endocrine therapy for oestrogen receptor-positive (ER+ve) post-menopausal breast cancer patients. Ais, by inhibiting the enzyme aromatase, block the conversion of androgen to oestrogen, reducing oestrogen levels. Resistance to Ais limits their clinical utilisation. Here, we show that overexpression of BQ323636.1 (BQ), a novel splice variant of nuclear co-repressor NCOR2, is associated with resistance to the non-steroidal aromatase inhibitor anastrozole in ER+ve post-menopausal breast cancer. Mechanistic study indicates that BQ overexpression enhances androgen receptor (AR) activity and in the presence of anastrozole, causes hyper-activation of AR signalling, which unexpectedly enhanced cell proliferation, through increased expression of CDK2, CDK4, and CCNE1. BQ overexpression reverses the effect of anastrozole in ER+ve breast cancer in an AR-dependent manner, whilst co-treatment with the AR antagonist bicalutamide recovered its therapeutic effect both in vitro and in vivo. Thus, for BQ-overexpressing breast cancer, targeting AR can combat anastrozole resistance. Clinical study of 268 primary breast cancer samples of ER+ve patients who had been treated with non-steroidal Ais showed 32.5% (38/117) of cases with combined high nuclear expression of BQ and AR, which were found to be significantly associated with Ai resistance. Non-steroidal Ai-treated patients with high nuclear expression of both BQ and AR had poorer overall, disease-specific, and disease-free survival. These findings suggest the importance of assessing BQ and AR expression status in the primary ER+ve breast tumour prior to Ai treatment. This may save patients from inappropriate treatment and enable effective therapy to be given at an early stage. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Use of PARPi among patients with HER2+ve MBC: Results from a real world dataset.

e13044 Background: Among individuals with germline mutations in BRCA1/ BRCA2 genes, life-time risk of developing breast cancer is approximately 50%. The majority of these cancers are HER2-ve with a low frequency of HER2+ve breast cancer (2.1%-10% in pts with BRCA1 mutations and 6.8%-13% of pts with BRCA2 mutations) with co-occurrence of BRCA mutation and HER2+ve status being a poor prognostic factor. PARPi have been shown in phase III trials to be effective in HER2-ve BRCA mutation MBC. The objective of this retrospective analysis was to look at the prognostic outcome associated with use of PARPi among pts with HER2 +ve BRCA mutated MBC in the real-world setting. Methods: We utilized a federated network of de-identified health data representing approximately 107 million pt lives available through the TriNetX Research Network. We identified patients with MBC who were treated with PARPi, and pts were assumed to have BRCA mutated MBC if they were recorded with a PARPi. Overall survival (OS) was computed using the Kaplan Meier product limit method. Pts with MBC were defined as having HER2+ve status if they received an anti-HER2 therapy after metastasis, HR+ve if they received endocrine therapy after metatstasis, and triple negative (TNBC) if they did not receive anti-HER2 therapy or endocrine therapy. Results: 1369pts with MBC were treated with PARPi, of whom 77.9%received olaparib. Mean age of pts was 57ys. 546(39.9%), 521(38.1%) and 73(5.3%) pts had TNBC, HR+ve/HER2-ve, and HER2+ve MBC, respectively. Among pts with HER2+ve disease, 35.2% and 74.0% had HR-ve and HR+ve MBC, respectively. Median time to use of PARPi was 7.1m, 15.1m, and 24.0m among pts with TNBC, HR+ve/HER2-ve, and HER2 +ve MBC respectively. Median OS was 44.4m, 47.0m, and 46.7m among pts with TNBC, HR+ve/HER2-ve and HER2+ve MBC respectively. Among pts with HER2+ve disease, median OS was 74.5m and 31.5m among pts with HR+ve and HER-ve disease, respectively (HR=0.27, p=0.0001). 321(23.4%) pts had brain metastases of whom 36.8%, 36.4% and 8.1% had TNBC, HR+ve/HER2-ve and HER2+ve MBC respectively. Among pts with HER2+ve MBC,38.3% received anti HER2 therapy before PARPi, 24.7% received anti HER2 therapy after PARPi and 37.0% received PARPi and anti HER2 therapy concurrently. Among pts with HER2+ve disease, median OS was 44.4m among those who received anti -HER2 therapy on or before PARPi and 93.8m among those who received anti-HER2 therapy after PARPi (HR 0.83, p=0.64).Among pts with brain metastases, median OS was 23.9m, 40.0m and 40.2m among pts with TNBC, HR+ve/HER-ve and HER2+ve MBC respectively. Conclusions: To our knowledge this is the first real world data set to report on the prognostic outcome of pts with HER2+ve BRCA mutated MBC. When PARPi inhibitors are given median OS is similar among the three subtypes of breast cancer. Although not significant, there appears to be a trend towards improved OS with earlier use of PARPi among patients with HER2+ve BRCA mutated MBC.

SRSF5 Regulates the Expression of BQ323636.1 to Modulate Tamoxifen Resistance in ER-Positive Breast Cancer

About 70% of breast cancer patients are oestrogen receptor-positive (ER +ve). Adjuvant endocrine therapy using tamoxifen (TAM) is an effective approach for preventing local recurrence and metastasis. However, around half of the patients will eventually develop resistance. Overexpression of BQ323636.1 (BQ) is one of the mechanisms that confer TAM resistance. BQ is an alternative splice variant of NCOR2. The inclusion of exon 11 generates mRNA for NCOR2, while the exclusion of exon 11 produces mRNA for BQ. The expression of SRSF5 is low in TAM-resistant breast cancer cells. Modulation of SRSF5 can affect the alternative splicing of NCOR2 to produce BQ. In vitro and in vivo studies confirmed that the knockdown of SRSF5 enhanced BQ expression, and conferred TAM resistance; in contrast, SRSF5 overexpression reduced BQ expression and, thus, reversed TAM resistance. Clinical investigation using a tissue microarray confirmed the inverse correlation of SRSF5 and BQ. Low SRSF5 expression was associated with TAM resistance, local recurrence and metastasis. Survival analyses showed that low SRSF5 expression was associated with poorer prognosis. We showed that SRPK1 can interact with SRSF5 to phosphorylate it. Inhibition of SRPK1 by a small inhibitor, SRPKIN-1, suppressed the phosphorylation of SRSF5. This enhanced the proportion of SRSF5 interacting with exon 11 of NCOR2, reducing the production of BQ mRNA. As expected, SRPKIN-1 reduced TAM resistance. Our study confirms that SRSF5 is essential for BQ expression. Modulating the activity of SRSF5 in ER +ve breast cancer will be a potential approach to combating TAM resistance.

The CDK4/6 Inhibitor Palbociclib Inhibits Estrogen-Positive and Triple Negative Breast Cancer Bone Metastasis In Vivo

CDK 4/6 inhibitors have demonstrated significant improved survival for patients with estrogen receptor (ER) positive breast cancer (BC). However, the ability of these promising agents to inhibit bone metastasis from either ER+ve or triple negative BC (TNBC) remains to be established. We therefore investigated the effects of the CDK 4/6 inhibitor, palbociclib, using in vivo models of breast cancer bone metastasis. In an ER+ve T47D model of spontaneous breast cancer metastasis from the mammary fat pad to bone, primary tumour growth and the number of hind limb skeletal tumours were significantly lower in palbociclib treated animals compared to vehicle controls. In the TNBC MDA-MB-231 model of metastatic outgrowth in bone (intracardiac route), continuous palbociclib treatment significantly inhibited tumour growth in bone compared to vehicle. When a 7-day break was introduced after 28 days (mimicking the clinical schedule), tumour growth resumed and was not inhibited by a second cycle of palbociclib, either alone or when combined with the bone-targeted agent, zoledronic acid (Zol), or a CDK7 inhibitor. Downstream phosphoprotein analysis of the MAPK pathway identified a number of phosphoproteins, such as p38, that may contribute to drug-insensitive tumour growth. These data encourage further investigation of targeting alternative pathways in CDK 4/6-insensitive tumour growth.

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.

Expression of substance P, neurokinin 1 receptor, Ki-67 and pyruvate kinase M2 in hormone receptor negative breast cancer and evaluation of impact on overall survival

BackgroundChronic inflammation is a hallmark of cancer, and it can be stimulated by many factors. Substance P (SP), through binding to neurokinin 1 receptor (NK1R), and pyruvate kinase M2 (PKM2) play critical roles in cancer development and progression via modulating the tumor microenvironment. This study aimed to investigate the prognostic significance of SP and PKM2 in combination with NK1R and Ki-67 in hormone receptor negative (HR-ve) breast cancer.MethodsImmunohistochemical expression levels of SP, NK1R, PKM2, and Ki-67 were measured in 144 paraffin-embedded breast cancer tissues (77 h -ve and 67 h + ve). SP, NK1R, and PKM2 were scored semiquantitatively, while Ki-67 was obtained by the percentage of total number of tumor cells with nuclear staining. The optimal cutoff value for SP, NK1R, PKM2, and Ki-67 were assessed by Cutoff Finder.ResultsHigh SP expression in HR -ve breast cancer was associated with TNM stage (p = 0.020), pT stage (p = 0.035), pN stage (p = 0.002), axillary lymph node metastasis (p = 0.003), and NK1R expression level (p = 0.010). In HR + ve breast cancer, SP expression was associated with HER2 status (p = 0.001) and PKM2 expression level (p = 0.012). Regarding PKM2 expression level, it significantly associated with HER2 status (p = 0.001) and history of DCIS (p = 0.046) in HR-ve tumors, and with HER2 status (p < 0.001) and SP expression level (p = 0.012) in HR + ve tumors. Survival analysis revealed that high SP level negatively impacted overall survival in HR-ve tumors that had low NK1R level (p = 0.021). Moreover, high SP negatively impacted overall survival in HR-ve tumors that had low Ki-67 level (p = 0.005). High PKM2 negatively impacted overall survival in HR-ve cases with low SP (p = 0.047).ConclusionCombined expression levels of SP with NK1R or Ki-67, and PKM2 with SP could be used to predict survival in breast cancer patients with HR-ve tumors. Our findings suggest a role of SP/NK1R pathway and PKM2 in HR-ve breast cancer pathogenesis which should be further investigated to unveil the underlying molecular mechanisms.

Modulating the Activity of Androgen Receptor for Treating Breast Cancer

The androgen receptor (AR) is a steroid hormone receptor widely detected in breast cancer. Evidence suggests that the AR might be a tumor suppressor in estrogen receptor alpha-positive (ERα+ve) breast cancer but a tumor promoter in estrogen receptor alpha-negative (ERα-ve) breast cancer. Modulating AR activity could be a potential strategy for treating breast cancer. For ERα+ve breast cancer, activation of the AR had been demonstrated to suppress the disease. In contrast, for ERα-ve breast cancer, blocking the AR could confer better prognosis to patients. These studies support the feasibility of utilizing AR modulators as anti-cancer drugs for different subtypes of breast cancer patients. Nevertheless, several issues still need to be addressed, such as the lack of standardization in the determination of AR positivity and the presence of AR splice variants. In future, the inclusion of the AR status in the breast cancer report at the time of diagnosis might help improve disease classification and treatment decision, thereby providing additional treatment strategies for breast cancer.

Genotypic and haplotype analysis of Interleukin-6 and -18 gene polymorphisms in association with clinicopathological factors in breast cancer.

Cytokines are multifunctional glycoproteins that play a vital role in the tumor microenvironment and progression of breast cancer. Genetic polymorphisms may influence the immune responses restrained by pro- and anti-inflammatory cytokine expression in tumors. Hence, the present study evaluated the contribution of Interleukin (IL) 6 (rs1800797, rs1800796, and rs1800795) and IL18 (rs1946518, rs187238, and rs549908) genotypes and their haplotypes to the risk, progression of breast cancer in South Indian population. The polymorphisms of IL6 -597G&gt;A, -572C&gt;G &amp; -174G&gt;C, and IL18 -607C&gt;A, -137G&gt;C, 105A&gt;T were genotyped through PCR-RFLP and As-PCR assays in the blood DNA of 600 subjects. We have performed haplotype, LD, univariate, multivariate logistic regression, and Kaplan-Meier analyses for the obtained data. The frequency of AA genotype &amp; A-allele of IL6 -597G&gt;A, and CC genotype &amp; C-allele of IL6 -174G&gt;C polymorphism was higher in breast cancer patients and was found to be significantly associated with late (advanced) stage, metastasis, etc. Further, IL18 -607C&gt;A, -137G&gt;C, and 105A&gt;T polymorphisms were found to be associated with lobular carcinoma subtype, PgR -ve, and HER2+ve breast cancer patients. In survival analysis, wehave observed that the C-allele of IL6-174G&gt;C polymorphismto be significantly associated with 5years of overall survival in breast cancer subjects. All SNPs of the IL6 and IL18 genes showed perfect LD; the G-C-C, A-G-G, and A-C-C haplotype combinations of IL6 gene conferred 2.09, 2.25, and 4.72 folds risk for breast cancer respectively. Hence, our results suggest the importance of genotypic and haplotype analysis of IL6 and IL18 gene variants in the progression and risk prediction of breast cancer.

Molecular crosstalk between CUEDC2 and ERα influences the clinical outcome by regulating mitosis in breast cancer.

Development of endocrine resistance in hormone-receptor-positive (HR+ve) subtype and lack of definitive target in triple-negative subtype challenge breast cancer management. Contributing to such endocrine resistance is a protein called CUEDC2. It degrades hormone receptors, estrogen receptor-α (ERα) and progesterone receptor. Higher level of CUEDC2 in ERα+ve breast cancer corresponded to poorer disease prognosis. It additionally influences mitotic progression. However, the crosstalk of these two CUEDC2-driven functions in the outcome of breast cancer remained elusive. We showed that CUEDC2 degrades ERα during mitosis, utilising the mitotic-ubiquitination-machinery. We elucidated the importance of mitosis-specific phosphorylation of CUEDC2 in this process. Furthermore, upregulated CUEDC2 overrode mitotic arrest, increasing aneuploidy. Finally, recruiting a prospective cohort of breast cancer, we found significantly upregulated CUEDC2 in HR-ve cases. Moreover, individuals with higher CUEDC2 levels showed a poorer progression-free-survival. Together, our data confirmed that CUEDC2 up-regulation renders ERα+ve malignancies to behave essentially as HR-ve tumors with the prevalence of aneuploidy. This study finds CUEDC2 as a potential prognostic marker and a therapeutic target in the clinical management of breast cancer.

Abstract 6399: SP in relation to NK1R and Ki67 predicts survival in hormone receptor negative breast cancer

Abstract Background: Substance P (SP) is a tachykinin that has been implicated in carcinogenesis in several types of cancer through binding to neurokinin 1 receptor (NK1R). This study aimed to investigate the expression levels of SP and NK1R in hormone receptor negative (HR -ve) versus positive (HR +ve) breast cancer tissues and their relationship with clinicopathological characteristics of patients, Ki-67 index, and overall survival rate. Methods: Immunohistochemical expression levels of SP, NK1R and Ki-67 were measured in 144 paraffin-embedded breast cancer tissues (77 HR -ve and 67 HR +ve). SP and NK1R were scored semiquantitatively, while Ki-67 was obtained by the percentage of total number of tumor cells with nuclear staining. The optimal cutoff value for SP, NK1R and Ki-67 were assessed by Cutoff Finder. Pearson Chi-square (χ2) and Fisher’s exact tests were used to compare the staining scores between groups. ANOVA and student’s t-test were used to compare group means. Kaplan-Meier method with log-rank test was used for survival analysis. Results: High expression of SP, NK1R and Ki-67 was observed in 41%, 36.8% and 38.9% of cases, respectively. Association analyses revealed that SP expression in HR -ve breast cancer was higher in pN3 tumors (p=0.002), positive axillary lymph node metastasis (p=0.003), and high NK1R expression (p=0.010). In HR+ve breast cancer, SP was lower in HER2 positive tumors (p=0.001). Regarding NK1R, the association analysis showed that low NK1R expression level in HR +ve tumors was related to stage IV (p=0.023), pN1 (p=0.006), and low Ki-67 index (p=0.038). Survival analysis revealed that high SP level negatively impacted overall survival in HR-ve tumors that had low NK1R level (p=0.021). Moreover, high SP negatively impacted overall survival in HR-ve tumors that had low Ki-67 level (p=0.005). Nevertheless, NK1R expression did not impact survival in HR-ve or HR+ve cases despite stratification by SP and Ki-67 expression (p&amp;gt;0.05). Conclusion: Up to our knowledge, this is the first study to investigate the prognostic potential of SP and NK1R in breast cancer. Combined expression levels of SP and NK1R or Ki-67 could be used to predict survival in breast cancer patients with HR-ve tumors. Our findings suggest the potential role of SP and NK1R as therapeutic targets in breast cancer. Citation Format: Maha S. Al-Keilani, Rana Elstaty, Mohammad A. Alqudah. SP in relation to NK1R and Ki67 predicts survival in hormone receptor negative breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 6399.

Oncometabolite profiling identifying estrogen-responsive genes in breast cancer.

e13611 Background: Metabolomic profiling in breast cancer (BC) is an emerging avenue to identify clinically actionable biomarkers as well as targeted therapeutics. Altered metabolic pathways has been identified in BC. Studies have discovered an association between oncometabolite levels, DNA methylation and other epigenetic changes, with prognosis in BC. Changes in cancer cells metabolism may thus indicate disease aggressiveness and its response to therapy. Methods: An in-silico based oncometabolite profiling was performed in ER +ve and TNBC (ER-/PR-/Her2-) data sets using NCBO-GEO tools. . Inclusion criteria included studies on Human subjects, having at least 2 ER+ PR+ and TNBC samples. After manually filtering the top 250 most significant differentially expressed genes in all studies, those with clear metabolic functions as per the GO category were pooled together, which included both the overexpressed and downregulated genes. 15 unique genes were cherry-picked and taken for further analysis out of which six were downregulated, and nine were upregulated. The identified genes harbouring ERE in their upstream 1000bp region were further analysed to identify CpG islands. In addition, we also performed a Bio-Reader based Text Mining Tool to streamline Pubmed abstracts with the positive strings “oncometabolite,” “breast cancer,” “stem cells” “survival”. We also queried against negative strings “sequencing,” “mutations,” “infections,” “drug-resistance” to develop a list of highly focused abstracts. Results: Novel estrogen-regulated oncometabolite that were differentially expressed in ER+ve vs TNBC BC were identified. Further, we reinforced the fact that 4 out of 7 targets had upstream CpG islands within 1000bp n Both upregulated AMY2A, B3GNT5, PNPLA3 and 2HG whereas and downregulated genes in PLCD4, FBP1 and CA12 along with one target identified from the literature were selectively expressed in ER+ve BC. Conclusions: Our study has identified estrogen-responsive metabolic genes involved in BC. We are currently validating our results in a wet lab setup from breast cancer patient samples. Validated targets may be tested for therapeutic intervention in BC.

Oncotype results compared to standard pathological markers: A five year audit 2015 -2020 NHS Lanarkshire

Aims: Oncotype Dx is a multi-gene test used to help define the prognosis in ER+ve node -ve breast cancer. This audit examines whether there is any further patient or pathological data that might refine the population that should get the oncotype funded.

91MO Randomized trial of neoadjuvant chemotherapy with or without concurrent aromatase inhibitor therapy to downstage ER+ve breast cancer: Breast Cancer Trials Group ANZ 1401 ELIMINATE trial

Chemotherapy (CT) and endocrine therapy (ET) are used sequentially in systemic management of ER+ve HER2-negative early breast cancer, leading to a delay in the initiation of ET. There is little randomized data to assess the benefits/harms of concurrent chemo-endocrine therapy (CET) using aromatase inhibitors (AI). We examined neoadjuvant CT with the addition of letrozole (plus goserelin in pre-/peri-menopausal women) versus CT alone.