Omission of Axillary Lymph Node Dissection in Patients with Residual Nodal Disease After Neoadjuvant Chemotherapy.

BACKGROUND: Axillary management after neoadjuvant chemotherapy (NAC) is evolving but axillary lymph node dissection (ALND) remains the standard of care for patients with residual nodal disease. The results of the Alliance A011202 trial evaluating the oncologic safety of ALND omission in this cohort are pending but we hypothesize that ALND omission is already increasing. METHODS: The National Cancer Database was queried to identify patients diagnosed with cT1-3N1M0 breast cancer who underwent NAC and had residual nodal disease (ypN1mi-2) from 2012 to 2021. Temporal trends in omission of completion ALND were assessed annually. Multivariable logistic and Cox regression models were used to identify factors associated with ALND omission and overall survival (OS), respectively. RESULTS: A total of 6101 patients were included; the majority presented with cT2 disease (57%), with 69% HER2+, 23% triple-negative, and 8% hormone receptor-positive/HER2-. Overall, 34% underwent sentinel lymph node biopsy (SLNB) alone. Rates of ALND were the lowest in the last 4 years of observation. After adjustment, treatment at community centers (vs. academic) and lower pathologic nodal burden were associated with omission of ALND. ALND omission was associated with a higher unadjusted OS (5-year OS: 86% SLNB alone vs. 84% ALND; log-rank p = 0.03), however this association was not maintained after adjustment. CONCLUSIONS: Despite the impending release of the Alliance A011202 results, omission of ALND in patients with residual nodal disease after NAC is increasing. This practice appears more prominent in community centers and in patients with a lower burden of residual nodal disease. No association with OS was noted.

Rates of Pathologic Complete Response and Overall Survival in Patients with Inflammatory Breast Cancer: A National Cancer Database Study.

BACKGROUND: Patients with inflammatory breast cancer (IBC) have worse survival compared with stage III non-IBC matched cohorts; however, the prognostic significance of achieving pathologic complete response (pCR) in the setting of IBC is not well described. We evaluated overall survival (OS) between IBC patients and non-IBC patients who achieved pCR. METHODS: Adult females diagnosed in 2010-2018 with clinical prognostic stage III unilateral invasive breast cancer treated with neoadjuvant chemotherapy (NAC) followed by surgery were selected from the National Cancer Database. Unadjusted OS from surgery was estimated using the Kaplan-Meier method, and log-rank tests were used to compare groups. Cox proportional hazard models were used to estimate the association of study groups with OS after adjustment for available covariates. RESULTS: The study included 38,390 patients; n = 4600 (12.0%) IBC and n = 33,790 (88.0%) non-IBC. Overall pCR rates were lower for IBC compared with non-IBC (20.7% vs. 23.3%; p < 0.001). Among those achieving pCR, 5-year mortality was higher for IBC patients (16.4%, 95% confidence interval [CI] 13.9-19.1%) versus non-IBC patients (9.1%, 95% CI 8.4-9.8%; log-rank p < 0.001). Among all patients achieving pCR, IBC remained associated with worse OS compared with non-IBC (hazard ratio 1.48, 95% CI 1.19-1.85; p < 0.001). CONCLUSION: We found a lower pCR rate and worse OS in IBC patients compared with non-IBC stage III patients. Despite effective systemic therapies, achieving a pCR for IBC patients may not carry the same prognostic impact compared with non-IBC stage III patients.

Triple-Negative Breast Cancer in Older Patients: Does SLNB Guide Therapy?

BACKGROUND: Older breast cancer patients represent a heterogeneous population. Studies demonstrate that sentinel lymph node biopsy (SLNB) omission may be appropriate in some clinical scenarios, yet patients with triple-negative breast cancer (TNBC) are often excluded from these studies. This study evaluated differences in treatment and survival for older patients with TNBC based on SLNB receipt and result. METHODS: Patients 70 years old or older with a diagnosis of cT1-2/cN0/M0 TNBC (2010-2019) who underwent surgery were selected from the National Cancer Database. Logistic regression estimated the association of SLNB with therapy, and Cox proportional hazards models estimated the association of SLNB with overall survival (OS) after adjustment for select factors. RESULTS: Of the 15,167 patients included in the study (median age, 77 years), 13.02% did not undergo SLNB, 5.14% had pN1 disease, 0.12% had pN2 disease, and 0.01% had pN3 disease. Most of the patients (83.9%) underwent surgery first, and 16.1% received neoadjuvant chemotherapy. Of those who underwent surgery first and SLNB, 6.2% had pN+ disease. Receipt of SLNB was associated with a higher likelihood of chemotherapy (odds ratio [OR] 1.85; 95% confidence interval [CI] 1.55-2.21), regardless of pN status. Compared with those who did not undergo a SLNB, a negative SLNB was significantly associated with lower mortality (hazard ratio [HR] 0.68; 95% CI 0.63-0.75), although there was no difference for a positive SLNB (HR 1.14; 95% CI 0.98-1.34). The patients receiving chemotherapy first showed no difference in survival based on SLNB receipt or result (p = 0.23). CONCLUSIONS: Most older patients with TNBC do not have nodal involvement and do not receive chemotherapy. The receipt and results of SLNB may be associated with outcomes for some who undergo surgery first, but not for those who receive neoadjuvant chemotherapy.

Assessment of Treatment Sequence in Patients With Stage III Breast Cancer.

INTRODUCTION: Stage III breast cancer is defined as locally advanced breast cancer and is treated with curative intent. Historically, overall survival (OS) did not differ based on treatment sequence (neoadjuvant chemotherapy [NAC] followed by surgery versus surgery followed by chemotherapy). Given recent advancements, we examined if treatment sequence may be associated with improved OS in a contemporary cohort of patients with stage III breast cancer. METHODS: Patients aged 18-80 years with prognostic stage III breast cancer who received chemotherapy and surgery were selected from the Surveillance, Epidemiology, and End Results database. Patients were stratified by treatment sequence (NAC versus surgery first). Unadjusted OS and breast cancer-specific survival (BCSS) were estimated using the Kaplan-Meier method and compared with log-rank tests. Cox proportional hazards models were used to estimate the association of treatment sequence with OS and BCSS after adjustment for selected covariates. RESULTS: The study included 26,573 patients; median follow-up was 62.0 months (95% confidence interval [CI] 61.0-63.0). Patients receiving NAC had a worse OS and BCSS compared to those who underwent surgery first (5-year OS rates 0.66 versus 0.73; 5-year BCSS rates 0.70 versus 0.77; both log-rank P < 0.001). After adjustment for tumor subtype, receipt of NAC (versus surgery first) remained associated with a worse OS (hazard ratio 1.27, 95% CI 1.2-1.34, P < 0.001) and BCSS (hazard ratio 1.35, 95% CI 1.27-1.43, P < 0.001). CONCLUSIONS: Based on data from patients treated largely before 2020, undergoing surgery first may be associated with improved survival, even after adjustment for known covariates including tumor subtype. These findings may inform treatment when caring for patients with operable, locally advanced breast cancer.

Utility of Axillary Staging in Older Patients with HER2-Positive Breast Cancer.

BACKGROUND: The utility of sentinel lymph node biopsy (SLNB) in older patients remains controversial. Advancements in human epidermal growth factor receptor 2 (HER2)-directed therapy have revolutionized disease response rates and prognosis, supporting efforts to re-evaluate the utility of SLNB. We aimed to assess the differences in treatment and overall survival (OS) in older patients with HER2-positive breast cancer based on SLNB. METHODS: Using the National Cancer Database (2010-2020), patients ≥ 70 years of age diagnosed with cT1-2/cN0/M0, HER2-positive breast cancer were identified. Logistic regression assessed associations with SLNB, systemic therapy, and radiation. Cox proportional hazard models were used to identify factors associated with OS. Analyses were stratified by treatment sequence, i.e. upfront surgery or neoadjuvant therapy (NAT) followed by surgery. RESULTS: Of the 17,609 patients included, 94% underwent upfront surgery (n = 16,492) and the remaining underwent NAT (n = 1117). Those who underwent SLNB were more likely to receive adjuvant therapy, irrespective of nodal status {upfront surgery/systemic therapy (odds ratio [OR] 2.82, 95% confidence interval [CI] 2.17-3.67); upfront surgery/radiation (OR 3.97, 95% CI 3.03-5.21); NAT/radiation (OR 5.69, 95% CI 1.83-17.69)}. The breast pathologic complete response (pCR) rate was highest among the hormone receptor (HR)-negative/HER2-positive subtype (50.0%), of which none were found to be ypN+. Comorbidity burden was associated with significantly lower rates of adjuvant systemic therapy and worse OS. CONCLUSIONS: Patients who underwent SLNB, regardless of pN status, were more likely to receive adjuvant therapy. Nodal positivity is exceedingly rare for patients with a breast pCR following NAT, especially among the HR-negative/HER2-positive subtype. It is reasonable to consider omission of SLNB in select subgroups of older patients with HER2-positive breast cancer.

Hidden secrets of the cancer genome: unlocking the impact of non-coding mutations in gene regulatory elements.

Discoveries in the field of genomics have revealed that non-coding genomic regions are not merely "junk DNA", but rather comprise critical elements involved in gene expression. These gene regulatory elements (GREs) include enhancers, insulators, silencers, and gene promoters. Notably, new evidence shows how mutations within these regions substantially influence gene expression programs, especially in the context of cancer. Advances in high-throughput sequencing technologies have accelerated the identification of somatic and germline single nucleotide mutations in non-coding genomic regions. This review provides an overview of somatic and germline non-coding single nucleotide alterations affecting transcription factor binding sites in GREs, specifically involved in cancer biology. It also summarizes the technologies available for exploring GREs and the challenges associated with studying and characterizing non-coding single nucleotide mutations. Understanding the role of GRE alterations in cancer is essential for improving diagnostic and prognostic capabilities in the precision medicine era, leading to enhanced patient-centered clinical outcomes.

Anatomy Versus Biology: What Guides Chemotherapy Decisions in Older Patients With Breast Cancer?

INTRODUCTION: With the increasing utilization of genomic assays, such as the Oncotype DX recurrence score (RS), the relevance of anatomic staging has been questioned for select older patients with breast cancer. We sought to evaluate differences in chemotherapy receipt and/or survival among older patients based on RS and sentinel lymph node biopsy (SLNB) receipt/result. METHODS: Patients aged ≥ 65 diagnosed with pT1-2/cN0/M0 hormone-receptor-positive (HR+)/HER2-breast cancer (2010-2019) were selected from the National Cancer Database. Logistic regression was used to identify factors associated with chemotherapy receipt. Cox proportional hazards models were used to estimate the association of RS/SLNB group with overall survival. A cost-benefit study was also performed. RESULTS: Of the 75,428 patients included, the majority had an intermediate RS (58.2% versus 27.9% low, 13.8% high) and were SLNB- (85.1% versus 11.6% SLNB+, 3.3% none). Chemotherapy was recommended for 13,442 patients (17.8%). After adjustment, chemotherapy receipt was more likely with higher RS and SLNB+. After adjustment, SLNB receipt/result was only associated with overall survival among those with an intermediate RS. However, returning to the OR for SLNB is not cost-effective. CONCLUSIONS: SLNB receipt/result was associated with survival for those with an intermediate RS, but not a low or high RS, suggesting that an SLNB may indeed be unnecessary for select older patients with breast cancer.

Racial/Ethnic Disparities in Pathologic Complete Response and Overall Survival in Patients With Triple-Negative Breast Cancer Treated With Neoadjuvant Chemotherapy.

PURPOSE: Black women have higher rates of death from triple-negative breast cancer (TNBC) than White women. We hypothesized that pathologic complete response (pCR) to neoadjuvant chemotherapy (NAC) and overall survival (OS) may vary by race/ethnicity in patients with TNBC. METHODS: We identified women 18 years and older with stage I-III TNBC who received NAC followed by surgery from the National Cancer Database (2010-2019). We excluded patients without race/ethnicity or pathology data. Primary outcomes were pCR rates and OS on the basis of race/ethnicity. RESULTS: Forty thousand eight hundred ninety women with TNBC met inclusion criteria (median age [IQR], 53 [44-61] years): 26,150 Non-Hispanic White (64%, NHW), 9,672 Non-Hispanic Black (23.7%, NHB), 3,267 Hispanic (8%), 1,368 Non-Hispanic Asian (3.3%, NHA), and 433 Non-Hispanic Other (1.1%, NHO) patients. Overall, 29.8% demonstrated pCR (NHW: 30.5%, NHB: 27%, Hispanic: 32.6%, NHA: 28.8%, NHO: 29.8%). Unadjusted OS was significantly higher for those with pCR compared with those with residual disease (5-year OS, 0.917 [95% CI, 0.911 to 0.923] v 0.667 [95% CI, 0.661 to 0.673], log-rank P < .001), and this association persisted after adjustment for demographic and tumor factors. The effect of achieving pCR on OS did not differ by race/ethnicity (interaction P = .10). However, NHB patients were less likely (odds ratio [OR], 0.89 [95% CI, 0.83 to 0.95], P = .001) and Hispanic patients were more likely (OR, 1.19 [95% CI, 1.08 to 1.31], P = .001) to achieve pCR than NHW patients. After adjustment for patient and disease factors, including achievement of pCR, Hispanic (hazard ratio [HR], 0.76 [95% CI, 0.69 to 0.85], P < .001) and NHA (HR, 0.64 [95% CI, 0.55 to 0.75], P < .001) race/ethnicity remained associated with OS. CONCLUSION: Odds of achieving pCR and OS in patients with TNBC appear to be associated with race/ethnicity. Additional research is necessary to understand how race/ethnicity is associated with rates of pCR and OS, whether related to socioeconomic factors or biologic variables, or both.

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.

Retained Biopsy Site Markers After Breast Lesion Surgical Resection: Associations With Residual Malignancy.

BACKGROUND. Biopsy site markers (BSMs) placed during image-guided core needle biopsy (CNB) are typically targeted for surgical excision, along with the breast imaging abnormality. Retained BSMs raise concern of incomplete resection of the breast abnormality. OBJECTIVE. The purpose of our study was to assess the frequency of residual malignancy in patients with retained BSMs identified on the initial mammography performed after breast lesion surgical excision. METHODS. This retrospective study included 30 patients (median age, 59 years) who underwent surgical resection between August 2015 and April 2022 of a borderline, high-risk, or malignant breast lesion after CNB and technically adequate preoperative image-guided localization, in whom the initial postoperative mammography report described a retained nonmigrated BSM. EMR data were extracted. The index pathology from CNB and initial surgical resection was classified as malignant or nonmalignant. The presence of residual malignancy after initial surgical resection required pathologic confirmation from subsequent tissue sampling; the absence of residual malignancy required 2 years of benign imaging follow-up. RESULTS. Thirteen specimen radiographs were interpreted intraoperatively by a surgeon with later radiologist interpretation, and 17 underwent real-time radiologist interpretation. Eighteen patients had malignant index pathology from the initially resected lesion. The frequency of residual malignancy on subsequent follow-up after initial surgical resection was higher in patients with malignant than nonmalignant index pathology (39% [7/18] vs 0% [0/12], respectively; p = .02). Among patients with malignant index pathology, the frequency of residual malignancy was higher in those without, than with, malignancy in the initial surgical specimen (80% [4/5] vs 23% [3/13]; p = .047). Also in these patients, the frequency of a positive interpretation of the initial postoperative mammography (BI-RADS category 4 or 6) was not significantly different between those with and without residual malignancy (57% [4/7] vs 55% [6/11]; p > .99). CONCLUSION. Patients with retained BSMs associated with malignant index lesions are at substantial risk of having residual malignancy. Initial postoperative mammography is not sufficient for excluding residual malignancy. CLINICAL IMPACT. Retained BSMs associated with index malignancy should be considered suspicious for residual malignancy. In this scenario, timely additional tissue sampling targeting the retained BSM is warranted, given the greater-than-2% chance of malignancy. Active surveillance is a reasonable management strategy in patients with retained BSMs from nonmalignant index lesions.

Chromatin insulation orchestrates matrix metalloproteinase gene cluster expression reprogramming in aggressive breast cancer tumors.

BACKGROUND: Triple-negative breast cancer (TNBC) is an aggressive subtype that exhibits a high incidence of distant metastases and lacks targeted therapeutic options. Here we explored how the epigenome contributes to matrix metalloprotease (MMP) dysregulation impacting tumor invasion, which is the first step of the metastatic process. METHODS: We combined RNA expression and chromatin interaction data to identify insulator elements potentially associated with MMP gene expression and invasion. We employed CRISPR/Cas9 to disrupt the CCCTC-Binding Factor (CTCF) binding site on an insulator element downstream of the MMP8 gene (IE8) in two TNBC cellular models. We characterized these models by combining Hi-C, ATAC-seq, and RNA-seq with functional experiments to determine invasive ability. The potential of our findings to predict the progression of ductal carcinoma in situ (DCIS), was tested in data from clinical specimens. RESULTS: We explored the clinical relevance of an insulator element located within the Chr11q22.2 locus, downstream of the MMP8 gene (IE8). This regulatory element resulted in a topologically associating domain (TAD) boundary that isolated nine MMP genes into two anti-correlated expression clusters. This expression pattern was associated with worse relapse-free (HR = 1.57 [1.06 - 2.33]; p = 0.023) and overall (HR = 2.65 [1.31 - 5.37], p = 0.005) survival of TNBC patients. After CRISPR/Cas9-mediated disruption of IE8, cancer cells showed a switch in the MMP expression signature, specifically downregulating the pro-invasive MMP1 gene and upregulating the antitumorigenic MMP8 gene, resulting in reduced invasive ability and collagen degradation. We observed that the MMP expression pattern predicts DCIS that eventually progresses into invasive ductal carcinomas (AUC = 0.77, p < 0.01). CONCLUSION: Our study demonstrates how the activation of an IE near the MMP8 gene determines the regional transcriptional regulation of MMP genes with opposing functional activity, ultimately influencing the invasive properties of aggressive forms of breast cancer.

Epigenetic Profiles of Triple-Negative Breast Cancers of African American and White Females.

Importance: Triple-negative breast cancer (TNBC) is the most aggressive breast cancer subtype and appears to have disproportionately higher incidence and worse outcomes among younger African American females. Objective: To investigate whether epigenetic differences exist in TNBCs of younger African American females that may explain clinical disparities seen in this patient group. Design, Setting, and Participants: This cross-sectional study used clinical, demographic, DNA methylation (HumanMethylation450; Illumina), and gene expression (RNA sequencing) data for US patient populations from publicly available data repositories (The Cancer Genome Atlas [TCGA], 2006-2012, and Gene Expression Omnibus [GEO], 2004-2013) accessed on April 13, 2021. White and African American females with TNBC identified in TCGA (69 patients) and a validation cohort of 210 African American patients from GEO (GSE142102) were included. Patients without available race or age data were excluded. Data were analyzed from September 2022 through April 2023. Main Outcomes and Measures: DNA methylation and gene expression profiles of TNBC tumors by race (self-reported) and age were assessed. Age was considered a dichotomous variable using age 50 years as the cutoff (younger [<50 years] vs older [≥50 years]). Results: A total of 69 female patients (34 African American [49.3%] and 35 White [50.7%]; mean [SD; range] age, 55.7 [11.6; 29-82] years) with TNBC were included in the DNA methylation analysis; these patients and 210 patients in the validation cohort were included in the gene expression analysis (279 patients). There were 1115 differentially methylated sites among younger African American females. The DNA methylation landscape on TNBC tumors in this population had increased odds of enrichment of hormone (odds ratio [OR], 1.82; 95% CI, 1.21 to 2.67; P = .003), muscle (OR, 1.85; 95% CI, 1.44 to 2.36; P < .001), and proliferation (OR, 3.14; 95% CI, 2.71 to 3.64; P < .001) pathways vs other groups (older African American females and all White females). Alterations in regulators of these molecular features in TNBCs of younger African American females were identified involving hormone modulation (downregulation of androgen receptor: fold change [FC] = -2.93; 95% CI, -4.76 to -2.11; P < .001) and upregulation of estrogen-related receptor α (FC = 0.86; 95% CI, 0.34 to 1.38; P = .002), muscle metabolism (upregulation of FOXC1: FC = 1.33; 95% CI, 0.62 to 2.03; P < .001), and proliferation mediators (upregulation of NOTCH1: FC = 0.71; 95% CI, 0.23 to 1.19; P = .004 and MYC (FC = 0.81; 95% CI, 0.18 to 1.45; P = .01). Conclusions and Relevance: These findings suggest that TNBC of younger African American females may represent a distinct epigenetic entity and offer novel insight into molecular alterations associated with TNBCs of this population. Understanding these epigenetic differences may lead to the development of more effective therapies for younger African American females, who have the highest incidence and worst outcomes from TNBC of any patient group.

A Pilot Study of Neoadjuvant Nivolumab, Ipilimumab, and Intralesional Oncolytic Virotherapy for HER2-negative Breast Cancer.

Purpose: Neoadjuvant combination immune checkpoint blockade and intralesional oncolytic virotherapy have the potential to activate antitumor responses in patients with breast cancer. Experimental Design: Eligibility for this pilot phase I trial included patients with localized HER2-negative breast cancer who received systemic nivolumab and ipilimumab and intratumor talimogene laherparepvec (T-VEC; NCT04185311). The primary objective was to evaluate the safety and adverse event profile of immunotherapy combined with T-VEC in patients with localized, HER2-negative breast cancer. Results: Six patients were enrolled, 4 having relapses after prior neoadjuvant chemotherapy and 2 who were previously untreated. Toxicities included 1 patient having grade 3 hypotension and type 1 diabetes mellitus, 3 patients with hypothyroidism, and all patients having constitutional symptoms known to be associated with the administration of T-VEC. One patient had a pathologic complete response, 3 patients had pathologic partial responses, 1 showed no significant response, and 1 had disease progression. Biopsies demonstrated increased immune cell infiltration in samples from patients who responded to therapy. Conclusions: This triple immunotherapy regimen provided responses in patients with advanced or relapsed HER2-negative breast cancer, at the expense of long-term toxicities. Significance: Systemic immune checkpoint blockade with a programmed death receptor 1 and a CTL antigen-4 blocking antibody, combined with intralesional oncolytic virotherapy, is a chemotherapy-free combination aimed at inducing an antitumor immune response locally and systemic immunity.

Neoadjuvant Chemotherapy and Endocrine Therapy for Older Patients with Estrogen Receptor Positive Breast Cancer: Comparison of Approaches.

BACKGROUND: Benefits of a pathologic complete response (pCR) following neoadjuvant therapy are well established, yet outcomes for older women are understudied. We sought to examine the pCR and overall survival (OS) rates of women with estrogen receptor (ER) positive breast cancer across age groups. METHODS: Women diagnosed with cT1-4, N0-3, M0, ER+/HER2- breast cancer (2010-2018) who underwent neoadjuvant chemotherapy (NACT) or neoadjuvant endocrine therapy (NET) followed by surgery were selected from the National Cancer Database and categorized by age. Differences were tested, and Cox proportional hazards models were used to estimate the association of response with OS after adjustment for covariates. RESULTS: In the 43,009-patient cohort, 84.8% received NACT and 15.2% received NET. Of those aged ≥ 70 (N = 5623), 51.0% received NACT, and 49.0% received NET. Compared with younger women receiving NACT, older women were less likely to have a breast or nodal pCR [no pCR by age: 85.1% (≥ 70 years) vs 82.2% (50-69 years) vs 77.7% (< 50 years), p < 0.001]. Rates of pCR were similarly low for all women receiving NET [no pCR by age: 95.6% (≥ 70 years) vs 95% (50-69 years) vs 96% (< 50 years), p = 0.06]. After adjustment, pCR after NACT was not associated with OS for older patients, but better survival outcomes were noted for older patients achieving pCR after NET. CONCLUSION: For women with ER+/HER2- breast cancer, pCR rates after NACT are lower in older women compared with younger women, and are equally low after NET for all women. However, pCR after NET is associated with improved OS among older women, unlike pCR after NACT.

Construction and validation of a gene expression classifier to predict immunotherapy response in primary triple-negative breast cancer.

BACKGROUND: Immune checkpoint inhibitors (ICI) improve clinical outcomes in triple-negative breast cancer (TNBC) patients. However, a subset of patients does not respond to treatment. Biomarkers that show ICI predictive potential in other solid tumors, such as levels of PD-L1 and the tumor mutational burden, among others, show a modest predictive performance in patients with TNBC. METHODS: We built machine learning models based on pre-ICI treatment gene expression profiles to construct gene expression classifiers to identify primary TNBC ICI-responder patients. This study involved 188 ICI-naïve and 721 specimens treated with ICI plus chemotherapy, including TNBC tumors, HR+/HER2- breast tumors, and other solid non-breast tumors. RESULTS: The 37-gene TNBC ICI predictive (TNBC-ICI) classifier performs well in predicting pathological complete response (pCR) to ICI plus chemotherapy on an independent TNBC validation cohort (AUC = 0.86). The TNBC-ICI classifier shows better performance than other molecular signatures, including PD-1 (PDCD1) and PD-L1 (CD274) gene expression (AUC = 0.67). Integrating TNBC-ICI with molecular signatures does not improve the efficiency of the classifier (AUC = 0.75). TNBC-ICI displays a modest accuracy in predicting ICI response in two different cohorts of patients with HR + /HER2- breast cancer (AUC = 0.72 to pembrolizumab and AUC = 0.75 to durvalumab). Evaluation of six cohorts of patients with non-breast solid tumors treated with ICI plus chemotherapy shows overall poor performance (median AUC = 0.67). CONCLUSION: TNBC-ICI predicts pCR to ICI plus chemotherapy in patients with primary TNBC. The study provides a guide to implementing the TNBC-ICI classifier in clinical studies. Further validations will consolidate a novel predictive panel to improve the treatment decision-making for patients with TNBC.

Triple-Negative Breast Cancer (TNBC) is an aggressive type of breast cancer, responsible for a substantial burden of breast cancer-related deaths. In recent years, immunotherapy, a therapy that triggers the patient's immune system to attack the tumor, has arisen as a promising treatment in various cancers, including TNBC. However, a subset of patients with TNBC does not respond to this treatment. Here, we employed advanced computational techniques to predict response to immunotherapy plus chemotherapy in patients with primary TNBC. Our method is more accurate than using other existing markers, such as PD-L1, but is not very accurate in patients with non-TNBC breast cancers or non-breast cancers. This method could potentially be used to better select patients for immunotherapy, upfront, avoiding the side effects and costs of treating patients in which immunotherapy might not work.