Axillary nodal disease burden is not associated with an elevated 21-gene recurrence score in post-menopausal women presenting with a clinically negative axilla.

BACKGROUND: The predictive and prognostic value of the recurrence score (RS) has emphasized the importance of tumor biology and has reduced the prognostic implications of limited nodal burden in post-menopausal women with HR+/HER2-invasive breast cancer (IBC). It is unclear whether routine axillary staging has a continued role in the management of small, clinically node negative (cN0) HR+/HER2- IBC. We sought to estimate the association of RS with pN stage. METHODS: Patients >50yo diagnosed with cN0, HR+/HER2- IBC (2015-2019) with an available RS were identified from the National Cancer Database. The clinicopathologic characteristics and rates of pN-stage (pN0, pN1, pN2/3) were compared for RS of ≤25 vs. >25. RESULTS: The median patient age was 64.1 (IQR 58-69) and the majority (75%) of tumors displayed ductal histology. Most (81.6%) were cT1 on presentation and pT1 (74.7%) on final pathology. There were 130,568 (86.2%) with a RS â€‹≤ â€‹25 and 20,879 (13.8%) with a RS â€‹> â€‹25. On final pathology, 128,995 (85.2%) were pN0 and 21,991 (14.5%) pN1. Of the pN1, 2699 (12.3%) yielded a RS â€‹> â€‹25. There were 461 (0.3%) patients with pN2-pN3 disease. Of those, 57 (12.4%) had RS â€‹> â€‹25. CONCLUSION: In our analysis, pN0 and pN1 tumors are biologically similar by gene expression assay in postmenopausal patients with similar proportions of high RS. These data support the notion that tumor biology examined via RS may have more prognostic and predictive value than metastatic dissemination to limited lymph nodes. These findings support the ongoing evaluation of routine axillary staging in postmenopausal patients with HR+/HER2- IBC.

Available Systemic Treatments and Emerging Therapies for Breast Cancer Brain Metastases.

OPINION STATEMENT: In 2023, breast cancer brain metastases (BCBrM) remain a major clinical challenge gaining well-deserved attention. Historically managed with local therapies alone, systemic therapies including small molecule inhibitors and antibody-drug conjugates (ADCs) have shown unprecedented activity in recent trials including patients with brain metastases. These advancements stem from efforts to include patients with stable and active BCBrM in early- and late-phase trial design. Tucatinib added to trastuzumab and capecitabine improves intracranial and extracranial progression-free survival and overall survival in stable and active human epidermal growth factor receptor 2 (HER2+)-positive brain metastases. Trastuzumab deruxtecan (T-DXd) has both shown impressive intracranial activity in stable and active HER2+ BCBrMs challenging historical thinking of ADCs' inability to penetrate the central nervous system (CNS). T-DXd has shown potent activity in HER2-low (immunohistochemistry scores of 1+ or 2+, non-amplified by fluorescence in situ hybridization) metastatic breast cancer and will be studied in HER2-low BCBrM as well. Novel endocrine therapies including oral selective estrogen downregulators (SERDs) and complete estrogen receptor antagonists (CERANs) are being studied in hormone receptor-positive BCBrM clinical trials due to robust intracranial activity in preclinical models. Triple-negative breast cancer (TNBC) brain metastases continue to portend the worst prognosis of all subtypes. Clinical trials leading to the approval of immune checkpoint inhibitors have enrolled few BCBrM patients leading to a lack of understanding of immunotherapies contribution in this subgroup. Data surrounding the use of poly(adenosine diphosphate-ribose) polymerase (PARP) inhibitors in patients with germline BRCA mutation carriers with CNS disease is hopeful. ADCs including those targeting low-level HER2 expression and TROP2 are under active investigation in triple-negative BCBrMs.

Survival Outcomes Among Patients with Metastatic Breast Cancer: Review of 47,000 Patients.

BACKGROUND: Although metastatic breast cancer (MBC) remains incurable, advances in therapies have improved survival. Using a contemporary dataset of de novo MBC patients, we explore how overall (OS) and cancer-specific survival (CSS) changed over time. METHODS: All patients with de novo MBC from 1988 to 2016 were selected from Surveillance, Epidemiology, and End Results (SEER) 18. Unadjusted OS and CSS were estimated by Kaplan-Meier method and stratified by disease characteristics. Cox proportional hazards models determined factors associated with survival. RESULTS: 47,034 patients were included, with median OS of 25 months and CSS of 27 months. Survival steadily improved over time (1988: 1-year OS 62%, CSS 65%; 2015: 1-year OS 72%, CSS 74%). Patients with triple-negative breast cancer (TNBC) had the worst prognosis and were most likely to die from MBC [versus human epidermal growth factor receptor 2 (HER2)+ and hormone receptor (HR)+/HER2-]. Those with ≥ 4 sites of metastatic disease were also more likely to die from MBC with nearly identical OS and CSS (5-year OS 9%, CSS 9%), when compared with those with 1 site (5-year OS 31%, CSS 35%). After adjustment, improved CSS was associated with bone-only disease [hazard ratio (HR) 0.88, 95% confidence interval (CI) 0.83-0.94], while TNBC (versus HER2+: HR 3.12, 95% CI 2.89-3.36) and > 3 sites of metastatic disease (versus 1 site: HR 3.24, 95% CI 2.68-3.91) were associated with worse CSS (all p < 0.001). CONCLUSIONS: Accurate prognostic estimates are essential for patient care. As treatments for patients with MBC have expanded, OS and CSS have improved, and more patients, particularly with limited distant disease or favorable tumor subtypes, are also dying from non-MBC causes.

Real-world Evidence of Diagnostic Testing and Treatment Patterns in US Patients With Breast Cancer With Implications for Treatment Biomarkers From RNA Sequencing Data.

OBJECTIVE/BACKGROUND: We performed a retrospective analysis of longitudinal real-world data (RWD) from patients with breast cancer to replicate results from clinical studies and demonstrate the feasibility of generating real-world evidence. We also assessed the value of transcriptome profiling as a complementary tool for determining molecular subtypes. METHODS: De-identified, longitudinal data were analyzed after abstraction from records of patients with breast cancer in the United States (US) structured and stored in the Tempus database. Demographics, clinical characteristics, molecular subtype, treatment history, and survival outcomes were assessed according to strict qualitative criteria. RNA sequencing and clinical data were used to predict molecular subtypes and signaling pathway enrichment. RESULTS: The clinical abstraction cohort (n = 4000) mirrored the demographics and clinical characteristics of patients with breast cancer in the US, indicating feasibility for RWE generation. Among patients who were human epidermal growth factor receptor 2-positive (HER2+), 74.2% received anti-HER2 therapy, with ∼70% starting within 3 months of a positive test result. Most non-treated patients were early stage. In this RWD set, 31.7% of patients with HER2+ immunohistochemistry (IHC) had discordant fluorescence in situ hybridization results recorded. Among patients with multiple HER2 IHC results at diagnosis, 18.6% exhibited intra-test discordance. Through development of a whole-transcriptome model to predict IHC receptor status in the molecular sequenced cohort (n = 400), molecular subtypes were resolved for all patients (n = 36) with equivocal HER2 statuses from abstracted test results. Receptor-related signaling pathways were differentially enriched between clinical molecular subtypes. CONCLUSIONS: RWD in the Tempus database mirrors the overall population of patients with breast cancer in the US. These results suggest that real-time, RWD analyses are feasible in a large, highly heterogeneous database. Furthermore, molecular data may aid deficiencies and discrepancies observed from breast cancer RWD.

Early Stage HER2-Positive Breast Cancers Not Achieving a pCR From Neoadjuvant Trastuzumab- or Pertuzumab-Based Regimens Have an Immunosuppressive Phenotype.

BACKGROUND: Stromal tumor-infiltrating lymphocytes (TILs) might predict pathologic complete response (pCR) in patients with HER2-positive (HER2+) breast cancer treated with trastuzumab (H). Docetaxel (T), carboplatin (C), H, and pertuzumab (P) have immune-modulating effects. Pre- and post-treatment immune biomarkers in cancers treated with neoadjuvant TCH with or without P are lacking. In this study we quantified baseline and changes in TILs, cluster of differentiation (CD) 4+, CD8+, FoxP3+, and PD-L1+ cells using immunohistochemistry (IHC) and quantified productive T-cell receptor ß (TCRß) rearrangements and TCRß clonality using next-generation sequencing (NGS) in 30 HER2+ breast cancer tissues treated with neoadjuvant H with or without P regimens. MATERIALS AND METHODS: Thirty pre- and post-neoadjuvant TCH (n = 4) or TCHP (n = 26) breast cancer tissues were identified. TILs were quantified manually using hematoxylin and eosin. CD4, CD8, FoxP3, and PD-L1 were stained using IHC. TCRß was evaluated using NGS. Immune infiltrates were compared between pCR and non-pCR groups using the Wilcoxon rank sum test. RESULTS: A pCR occurred in 15 (n = 15; 50%) cancers (TCH n = 2; TCHP, n = 13). Pretreatment TILs, CD4+, CD8+, FoxP3+, and PD-L1+ cells were not associated with response (P = .42, P = .55, P = .19, P = .66, P = .87, respectively. Pretreatment productive TCRß and TCRß clonality did not predict response, P = .84 and P = .40, respectively). However, post-treatment CD4+ and FoxP3+ cells (T-regulatory cells) were elevated in the non-pCR cohort (P = .042 and P = .082, respectively). CONCLUSION: An increase in regulatory T cells in non-pCR tissues suggests the development of an immunosuppressive phenotype. Further investigation in a larger cohort of samples is warranted to validate these findings.

HR+, HER2- Advanced Breast Cancer and CDK4/6 Inhibitors: Mode of Action, Clinical Activity, and Safety Profiles.

BACKGROUND: Cyclin-dependent kinase (CDK) 4/6 inhibitor-based therapies have shown great promise in improving clinical outcomes for patients with hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) advanced breast cancer. OBJECTIVES: 1. Discuss the mode of action of the three CDK4/6 inhibitors in late clinical development: palbociclib (PD-0332991; Pfizer), ribociclib (LEE011; Novartis), and abemaciclib (LY2835219; Lilly). 2. Describe the efficacy and safety data relating to their use in HR+, HER2- advanced breast cancer. 3. Discuss the key side effects associated with CDK4/6 inhibitors along with considerations for adverse event management and patient monitoring. METHOD: Relevant information and data were assimilated from manuscripts, congress publications, and online sources. RESULTS: CDK4/6 inhibitors have demonstrated improved progression-free survival in combination with endocrine therapy compared with endocrine therapy alone. The side-effect profile of each agent is described, along with implications for patient monitoring, and considerations for patient care providers and pharmacists. CONCLUSION: Addition of a CDK4/6 inhibitor to endocrine therapy increases efficacy and delays disease progression. Insight into the unique side-effect profiles of this class of agents and effective patient monitoring will facilitate the successful use of CDK4/6 inhibitor-based therapies in the clinic.