Receptor-positive HER2-negative Breast Research Articles

Abstract OT1-12-04: A phase IIIb, open-label, local, multicenter study of the molecular features of postmenopausal women with hormone receptor-positive (HR+) HER2-negative advanced breast cancer on first-line treatment with ribociclib and letrozole (BioItaLEE)

Abstract Background: characterizing the molecular features associated with prolonged benefit from CDK 4/6 inhibitors in HR+ HER2- BC and the acquired genomic alterations following treatment progression remains an unmet need and is crucial for leveraging the efficacy of CDK4/6 inhibitors and for elucidating resistance mechanisms. Identifying pre-treatment or pharmacodynamic predictive markers of treatment benefit, as well as predictive markers of toxicity by correlating pharmacogenomics with adverse events, could help physicians to select patients who may benefit the most from these therapies and improve the clinical management. Trial design: this is an Italian, multicenter, open-label, single-arm trial (NCT03439046) enrolling approximately 350 HR+ HER2- aBC first line patients in 48 sites. Patients are treated with ribociclib and letrozole and eligibility criteria are similar to the MONALEESA-2 trial. Patients will be followed for safety and efficacy outcomes. An extensive prospective collection of biological samples at different time points will be performed as follow: whole blood and plasma at baseline, cycle 1-D15, cycle 2-D1, at first imaging evaluation, at cycle 24-D1, as well as upon progression of disease; newly obtained tissue biopsies at baseline and at progression; a buccal swab for pharmacogenetics at baseline. Efficacy and safety data will be collected for all patients. Aims: the primary objective of this study is to identify circulating tumor DNA (ctDNA) alterations at baseline, to describe their evolution during treatment and to evaluate the association with clinical outcome. An optimized Next Generation Sequencing approach for the detection of low abundance events in ctDNA will be adopted. Single nucleotide variants and copy number alterations in a customized panel of genes relevant for BC will be analyzed. Secondary objectives include the evaluation of: serum thymidine kinase 1 activity over time as blood marker of early response; ctDNA alterations across different patient profiles and clonal evolution of ctDNA alterations under treatment; ctDNA alterations at time of tumor progression; correlation between mutational status detected in ctDNA and matched tissue samples; features of tumor microenvironment before and after treatment; association of pharmacogenomics patterns with adverse events and clinical outcomes. Clinical efficacy and safety of ribociclib + letrozole will be correlated with all biological endpoints. Statistical methods: the study is descriptive in nature and no formal statistical testing is necessary or applicable. Sample size is aligned with other biomarker studies and is based on a feasibility analysis of the trial and relative timelines. Present accrual: The first study patient was screened in Feb 2018, as in June 2018, 126 patients have been screened and 78 patients have been enrolled. Citation Format: De Laurentiis M, Arpino G, Bianchini G, Malorni L, Castelletti D, De Vecchi R, Grasso D. A phase IIIb, open-label, local, multicenter study of the molecular features of postmenopausal women with hormone receptor-positive (HR+) HER2-negative advanced breast cancer on first-line treatment with ribociclib and letrozole (BioItaLEE) [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr OT1-12-04.

Abstract P4-01-16: Detection of plasma tumor DNA (ptDNA) in patients with hormone receptor-positive HER2-negative (HR+HER2-) early breast cancer (EBC) in clinical remission

Abstract Background: Detection of ptDNA in patients with HR+HER2- EBC in clinical remission may impact recommendations for type and duration of adjuvant endocrine therapy. A sensitive technique to identify tumor mutations in plasma is BEAMing digital PCR. The frequency and timing of detectable mutations in plasma of patients in clinical remission from HR+HER2- EBC are unknown. Methods: We screened a prospective institutional repository for patients that met inclusion criteria. Eligible patients must have been enrolled to the repository between 12/1/2008 (repository start) and 12/31/2016, had HR+HER2- EBC, received follow-up at Johns Hopkins with appointment scheduled between 3/1/2017 and 12/31/2017, completed curative surgery at least 6 months prior to this appointment, been recommended or initiated adjuvant endocrine therapy, and been in clinical remission. Appropriate patients were approached for a current blood sample during their follow-up appointment in 2017. Blood was analyzed using a BEAMing digital PCR platform (Sysmex Inostics OncoBEAM™) for AKT1, PIK3CA, and ESR1 mutations. Results: We identified 67 eligible patients and collected blood from 60. Most patients had relatively low risk disease including 40 patients (67%) with stage I disease, and only 21 patients (35%) received chemotherapy. Patients were evenly divided between receiving tamoxifen or an aromatase inhibitor, and some patients switched from one to the other. The majority of patients (68%) had surgery between 1 and 5 years prior to the current blood draw. Detailed patient characteristics are provided in Table 1. Two out of the 60 patients had detectable ptDNA, both with stage IIA disease. One patient had a mutation in the ESR1 ligand-binding domain P535H 9 months after surgery and while taking adjuvant tamoxifen for 7 months. Sanger sequencing of primary tumor tissue did not reveal this mutation. Another patient had a mutation in PIK3CA exon 9 E542K 9.5 years after surgery and after taking adjuvant tamoxifen for at least 7 years. Amplifying this locus in DNA from primary tumor tissue was unsuccessful; further analysis using droplet digital PCR (ddPCR) is planned. Conclusions: Detection of ptDNA was feasible in a relatively low-risk group of patients with HR+HER2- EBC in clinical remission. Sampling a larger number of patients is needed to gain more understanding of the frequency and timing of detectable ptDNA. Next steps should also focus on determining the natural history of detectable ptDNA in patients with HR+HER2 EBC in clinical remission which may impact adjuvant treatment recommendations. Funding sources: Komen SAC110053, P30 CA06973, Breast Cancer Research Foundation Table 1:Characteristics of included patients N (%)Total patients60Age at diagnosis, median(range)57 (30-77)Female59 (98)Caucasian54 (90)Postmenopausal at diagnosis36 (60)Tumor size <2 cm42 (70)Node negative45 (75)Invasive ductal histology44 (73)Received adjuvant chemotherapy21 (35)Type of adjuvant endocrine therapy Tamoxifen25 (42)Aromatase inhibitor26 (43)Tamoxifen and AI7 (12)None2 (3)Time after surgery 6 months to <1 year6 (10)1 year to <5 years41 (68)5 years to <10 years13 (22) Citation Format: Shah M, Hunter N, Ensminger J, Shinn D, Cole AJ, Quinn HE, Edelstein DL, Wang C, Smith KL, Richardson AL, Cimino-Mathews A, Wolff AC, Cravero K, Park BH, Stearns V. Detection of plasma tumor DNA (ptDNA) in patients with hormone receptor-positive HER2-negative (HR+HER2-) early breast cancer (EBC) in clinical remission [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P4-01-16.

A high-risk 70-gene signature is not associated with the detection of tumor cell dissemination to the bone marrow.

The 70-gene signature (70-GS) is a prognostic tool, grouping patients in risk groups to assess their need for adjuvant chemotherapy. Tumor cell dissemination to the bone marrow is a marker of minimal residual disease and associated with impaired survival. In this study, we aimed to evaluate whether 70-GS is associated with the presence of disseminated tumor cells (DTCs) in the bone marrow of patients with early breast cancer. In patients with hormone receptor-positive HER2-negative early breast cancer, the 70-GS was obtained and the presence of DTCs was immunohistochemically evaluated using cytokeratin staining with the A45-B/B3 antibody. 149 patients were included into the analysis. 40 (27%) had a high-risk 70-GS and 35 (23%) had detectable DTCs in their bone marrow. 9 (22%) of the 40 patients with high-risk 70-GS and 26 (24%) of the 109 patients with a low-risk 70-GS were positive for DTCs (p=0.863). As both 70-GS and DTC detection are known prognostic factors but do not seem to correlate, a follow-up on a larger cohort is warranted to evaluate if a combination of the two is able to better stratify the relapse risk in early breast cancer patients.

Dissecting the Biological Heterogeneity within Hormone Receptor Positive HER2 Negative Breast Cancer by Gene Expression Markers Identifies Indolent Tumors within Late Stage Disease

Hormone receptor positive (HR+) breast cancers are a heterogeneous class with differential prognosis. Although more than half of Indian women present with advanced disease, many such patients do well. We have attempted identification of biologically indolent tumors within HR+HER2- tumors based on gene expression using histological grade as a guide to tumor aggression. 144 HR+HER2- tumors were divided into subclasses based on scores derived by using transcript levels of multiple genes representing survival, proliferation, and apoptotic pathways and compared to classification by Ki-67 labeling index (LI). Clinical characters and disease free survival were compared between the subclasses. The findings were independently validated in the METABRIC data set. Using the previously established estrogen receptor (ER) down stream activity equation, 20% of the tumors with greater than 10% HR positivity by immunohistochemistry (IHC) were still found to have inadequate ER function. A tumor aggression probability score was used to segregate the remainder of tumors into indolent (22%) and aggressive (58%) classes. Significant difference in disease specific survival was seen between the groups (P = .02). Aggression probability based subclassification had a higher hazard ratio and also independent prognostic value (P<.05). Independent validation of the gene panel in the METABRIC data set showed all 3 classes; indolent (24%), aggressive (68%), and insufficient ER signaling (7%) with differential survival (P = .01). In agreement with other recent reports, biologically indolent tumors can be identified with small sets of gene panels and these tumors exist in a population with predominantly late stage disease.

Targeted intraoperative radiotherapy tumor bed boost during breast conserving surgery after neoadjuvant chemotherapy in hormone receptor positive HER2 negative breast cancer.

e12090 Background: Targeted intraoperative radiotherapy (TARGIT – IORT) as a tumor bed boost during breast conserving surgery is an established option for women with early breast cancer. In a previous study our group could show a beneficial effect of TARGIT-IORT on overall survival after neoadjuvant chemotherapy compared to an external boost in an unselected cohort. In this study we present an analysis of the hormone receptor positive HER2 negative subgroup. Methods: In this non-randomized cohort study involving 46 hormone receptor positive HER2 negative patients after NACT we compared outcomes of 21 patients who received a tumour bed boost with IORT (TARGIT-IORT) during lumpectomy versus 25 patients treated in the previous 13 months with external (EBRT) boost. All patients received whole breast radiotherapy. Disease free survival (DFS) and overall survival (OS) were compared. Results: There were no statistical differences between the two groups regarding tumor size, grading, nodal status and pCR rates. Median follow up was 49 months. Whereas DFS was not significantly different between the groups the 5-year Kaplan-Meier estimate of OS was significantly better by 21% with IORT: TARGIT-IORT 0 events 100%, EBRT 5 events 79%, log rank p = 0.028. Conclusions: Although our results have to be interpreted with caution due to a possible selection bias and the small numbers, we could show that the improved OS as previously demonstrated in our dataset for TARGIT-IORT during lumpectomy after neoadjuvant chemotherapy as a tumor bed boost compared to an external beam radiotherapy boost is driven by the hormone receptor positive HER2 negative subgroup. These data give further support to the inclusion of such patients in the TARGIT-B (Boost) randomised trial that is testing whether IORT boost is superior to EBRT boost and to the analysis of subgroups based on tumor biology in this trial.

Abstract P4-07-10: Epithelial mesenchymal transition associated with high miR-221 and integrin β6 leads to poor prognosis in hormone receptor positive HER2 negative breast cancers

Abstract Background: MicroRNA mediated molecular alterations are involved in the initiation and progression of cancer. Altered expression of multiple microRNAs is associated with endocrine resistance in hormone receptor positive HER2 negative (HR+/HER2-ve) cancer. The role of miR-221 in inducing epithelial to mesenchymal transition (EMT) is well documented especially in cell line model systems. However, the detailed mechanism of specific microRNAs in intrinsic and acquired resistance to endocrine therapy needs to be worked out. In addition, more needs to be done in the documentation of these mechanisms in human breast cancer specimens with complete clinical documentation and long-term follow-up. In this study, we have evaluated the clinical significance of miR-221 and its mechanistic role in EMT using human specimens and cell line models. Materials and Methods: Formalin fixed paraffin embedded tumor from 129 HR+/HER2-ve breast cancer patients with a median follow up of 63 months were used for estimation of miR-221 by quantitative real time PCR. Expression levels of genes which are direct targets of miR-221 and related genes in EMT were analysed from these tumors. Survival between miR-221 high and low groups was compared by Kaplan Meier survival curves and prognostic relevance was estimated by Cox proportional hazard model. Cell line experiments to investigate the role of miR-221 in inducing EMT through integrin β6 are underway in both wild type and tamoxifen resistant MCF-7 cell lines (A gift from Prof Ben Ho Park, Johns Hopkins University School of Medicine). Results: A significant elevated level of miR-221 was observed in small proportion (14%) of HR+/HER2-ve tumors. miR-221 expression had an inverse correlation with both ER protein and ESR1 mRNA levels within HR+/HER2-ve tumors. Tumors with high levels of miR-221 showed significantly higher expression of integrin β6 which is a robust marker of EMT. Patients with high expression of miR-221 had a poorer survival in Kaplan Meier analysis. Results of interrogation of EMT mediated through integrin related pathways involving miR-221 in cell line models will be presented. Discussion: The association between miR-221 and integrin β6 in HR+/HER2-ve breast cancer with endocrine resistance suggests a potential link between an epigenetic regulator and a mediator of tumor-stromal interaction. The other mediators involved in this pathway are being investigated. miR-221 could be potentially used as a marker for identification of a poor prognostic subtype within HR+/HER2-ve breast cancers. Citation Format: Prabhu JS, Kaul R, Korlimarla A, Desai K, Gangadharan C, Rajarajan S, Nair MG, Alexander A, Kaluve R, Manjunath S, Correa M, Prasad MSN, Patil S, Srinath BS, Sridhar TS. Epithelial mesenchymal transition associated with high miR-221 and integrin β6 leads to poor prognosis in hormone receptor positive HER2 negative breast cancers [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P4-07-10.

Abstract P4-22-09: A phase 2 open label study of everolimus in combination with endocrine therapy in resistant hormone receptor-positive HER2-negative advanced breast cancer

Abstract Background: Therapies targeting estrogen receptor (ER) signaling are standard for patients (pts) with hormone receptor positive (HR+) (ER and/or progesterone receptor [PR] positive) metastatic breast cancer (MBC). Dysregulation of the mammalian target of rapamycin (mTOR) pathway has been associated with endocrine therapy (ET) resistance. BOLERO-2 demonstrated that the addition of the mTOR inhibitor, everolimus (EVE), to exemestane doubled the PFS in HR+ HER2- MBC pts who previously progressed on nonsteroidal aromatase inhibitor therapy.The premise of this phase 2 trial in HR+ MBC is that the addition of EVE to the last ET on which the disease progressed may restore sensitivity to ET and extend the benefit of the anti-estrogen therapy. Methods: Pts ≥18 yrs with HR+, HER2- unresectable, locally recurrent, or MBC refractory to ET in either the adjuvant or advanced/metastatic setting. 0-1 chemotherapy (chemo) regimens for MBC were permitted. Post-/ pre-/peri-menopausal women were eligible with ovarian function suppression permitted. Additional eligibility requirements include: no prior mTOR inhibitor therapy, measurable or evaluable disease, ECOG ≤2, adequate bone marrow and organ function. EVE (10 mg PO daily) was administered on a 4-wk cycle in combination with the same dose and schedule of the last ET to which their disease became resistant. Disease assessments were performed every 2 cycles and treatment continued until disease progression or unacceptable toxicity. Blood samples and archival tumor were collected respectively for the VeriStrat Assay and for the Foundation One molecular profiling platform. Results: 48 pts were enrolled; data from 26 pts is presented. Median age 63.5 yrs (range, 36-81) with 46% ≥ 65 yrs. 14 (54%) pts had received chemo in the adjuvant setting, 9 pts (35%) received chemo for MBC, and 4 pts (15%) received chemo in both settings. All pts had at least 1 prior hormonal therapy; 9 pts received ≥ 3 hormonal agents. EVE was combined with tamoxifen (27%), AIs (61%), and fulvestrant (12%). Median time on treatment was 18.6 wks (range 1-48.9 weeks). 5 pts (19%) remain on treatment and 21 (81%) have discontinued therapy due to: disease progression - 17, toxicity -2, and other causes - 2. 23 pts were evaluable for response. 1 pt on fulvestrant plus EVE had a PR and 18 pts (78%) had SD as best response, with SD &amp;gt; 6 mos in 7 pts, for a clinical benefit rate (CR+PR+ SD ≥ 6 months) of 35%. With a median follow up of 11 mos (range 2-16 mos), the median PFS was 6.6 months (range 3.6-9.4); the median OS has not been reached. Treatment-related adverse events consisted mostly of stomatitis, rash and fatigue with few G3 events: stomatitis 3 pts, rash 2 pts, and 1 each of fatigue, edema, and neutropenia. G1 pneumonitis was present in 2 pts. There were no G4 events or treatment related deaths. Conclusions: In HR+ HER2- advanced/MBC patients who progressed on prior ET, the addition of EVE to the ET to which their disease became resistant, resulted in 1 PR and 7 pts with SD &amp;gt; 6 mos. The results of the full study population will be presented. Modulation of the mTOR/AKT/PI3K pathway with EVE may extend the benefit of ET, even after tumor progression on ET alone. Citation Format: Yardley DA, Blakely L, Hemphill B, Joseph M, Liggett W, Daniel B, Castrellon A, Shastry M, Finney L, DeBusk L, Hainsworth JD, Burris III HA. A phase 2 open label study of everolimus in combination with endocrine therapy in resistant hormone receptor-positive HER2-negative advanced breast cancer [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P4-22-09.

Abstract OT2-1-08: A phase II open label study of everolimus in combination with anti-estrogen therapy in hormone receptor-positive HER2-negative advanced breast cancer

Abstract Background: Hormone receptor positive (HR+) breast cancer, defined as estrogen receptor and/or progesterone receptor positive, accounts for 70% of invasive breast cancers. While most HR+ tumors initially respond to anti-estrogen therapy, resistance, linked to crosstalk between cell signaling and signal transduction pathways, subsequently develops in almost 100%. Preclinical data has shown that the PI3K/Akt/mammalian target of rapamycin (mTOR) pathway is activated in long-term estrogen-deprived and aromatase inhibitor-resistant breast cancer cells. It is hypothesized that in this group of endocrine-resistant patients (pts), resistance to anti-estrogen therapy is driven by the PI3K/Akt/mTOR pathway and hence the inhibition of this pathway may reverse resistance. This study will evaluate the efficacy of adding everolimus (an inhibitor of mTOR) to anti-estrogen therapy in pts with HR+ metastatic breast cancer (MBC) who have progressed on anti-estrogen therapy. Study Objectives: This multi-center, open-label Phase II trial is designed to determine the efficacy (primary endpoint is PFS), safety and tolerability of everolimus in combination with anti-estrogen therapy in pts with HR+, HER2-negative MBC with disease progression on prior anti-estrogen therapy. An exploratory objective of this study is to evaluate the prognostic value of the VeriStrat assay in this population. VeriStrat testing has been used to predict treatment efficacy in clinical trials of non small cell lung cancer, head and neck squamous carcinoma, and MBC. Eligibility: Pts ≥18 years with HR+, HER2-negative breast cancer that is either unresectable, locally recurrent, or metastatic are eligible. Pts must have progressed on anti-estrogen therapy (recurrence while on/within 12 months of treatment for early stage breast cancer, or progressed while on/within 1 month of treatment for advanced/MBC), but anti-estrogen therapy is not required to be the last therapy prior to enrollment. No washout for anti-estrogen therapy is required, and ≤1 previous chemotherapy regimen is allowed. Post menopausal or pre-/ peri-menopausal women on tamoxifen are eligible and ovarian function suppression is permitted. Prior treatment with a mTOR inhibitor is not allowed. Additional eligibility requirements include: measurable or evaluable disease, ECOG ≤2, adequate bone marrow and organ function and an adequate lipid profile (fasting serum cholesterol ≤300 mg/dL or ≤7.75 mmol/L and fasting triglyceride ≤2.5 x ULN). Trial Design: Everolimus will be administered at a dose of 10 mg PO daily in combination with the FDA prescribed doses of the most recent anti-estrogen therapy on which the pt progressed. Treatment cycles will be 4 weeks, with response evaluations by CT scans every 2 cycles. Pts will be treated until disease progression or unacceptable toxicity occurs. With an alpha=0.5, a sample size of 42 will provide 80% power to detect improvement in median PFS. Blood samples for the VeriStrat assay will be collected at baseline, on Cycle 3 Day 1, at disease progression and at the first follow-up visit post disease progression. Archival tumor tissue samples will be collected for comprehensive genomic profiling. This trial has a total accrual goal of 46 pts. Citation Format: Denise A Yardley, Mythili Shastry, Laura M DeBusk, Howard A Burris III, John D Hainsworth. A phase II open label study of everolimus in combination with anti-estrogen therapy in hormone receptor-positive HER2-negative advanced breast cancer [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr OT2-1-08.