Faculty Bibliography

Breast cancer disparities in outcomes remain a persistent challenge in the USA, with survival influenced by neighborhood context, access to resources, and the applicability of existing scientific evidence across populations. These disparities arise from complex, intersectional factors spanning social, structural, and biologic domains. While social determinants of health (SDOH) are strongly associated with breast cancer incidence and outcomes, the causality of biologic mechanisms underlying these associations remain incompletely understood. This review examines breast cancer disparities at the societal level and highlights emerging research that links social epidemiology with tumor biology, emphasizing the need for continued investigation using advanced genomic and epigenetic approaches to better understand and ultimately reduce inequities in breast cancer outcomes.

Cancer disparities among populations in the United States are a persistent and ongoing challenge. Medical mistrust (MM), or the tendency to distrust individuals and systems even at the cost of one's own well-being, has been implicated in contributing to worse health outcomes. Thus, understanding the relationship between MM and cancer care disparities may inform effective interventions to improve outcomes for all. We conducted a two-step review: (1) a standard review to examine the relationship between MM and the cancer continuum of care, and (2) a systematic review to assess interventions targeted to mitigate MM in cancer care. The standard review included eleven studies, which revealed that MM impacted cancer screening, treatment adherence, clinical trial participation, and access to social support. Key mediators of MM included patient-provider discordance, health-related and sociodemographic-related discrimination, perceptions of Western medicine, low quality care, and health insurance. Our systematic review yielded twelve interventions-67% tailored towards screening, 17% towards patient navigation services, and 17% towards clinical trial participation. Key methods included adapting patient-centered (e.g. gathering patient perspectives, increasing racial and ethnic representation) and community-based approaches (e.g. use of churches and training family members to disseminate patient education) to overall create culturally tailored interventions against MM across the cancer continuum of care.

Patients with triple negative breast cancer (TNBC) and comorbid Type 2 Diabetes (T2D), characterized by insulin resistance of adipose tissue, have higher risk of metastasis and shorter survival. Adipocytes are the main non-malignant cells of the breast tumor microenvironment (TME). However, adipocyte metabolism is usually ignored in oncology and mechanisms that couple T2D to TNBC outcomes are poorly understood. Here we hypothesized that exosomes, small vesicles secreted by TME breast adipocytes, drive epithelial-to-mesenchymal transition (EMT) and metastasis in TNBC via miRNAs. Exosomes were purified from conditioned media of 3T3-L1 mature adipocytes, either insulin-sensitive (IS) or insulin-resistant (IR). Murine 4T1 cells, a TNBC model, were treated with exosomes in vitro (72h). EMT, proliferation and angiogenesis were elevated in IR vs. control and IS. Brain metastases showed more mesenchymal morphology and EMT enrichment in the IR group. MiR- 145a-3p is highly differentially expressed between IS and IR, and potentially regulates metastasis. Implications: IR adipocyte exosomes modify the TME, enhance EMT, and promote brain metastasis-likely via miRNA pathways-suggesting that metabolic diseases like T2D foster a pro-metastatic TME, reducing survival, warranting close monitoring and potential metabolic interventions in TNBC patients with T2D.

Women with obesity-driven diabetes are predisposed to more aggressive breast cancers. However, patient metabolic status does not fully inform the current standard of care. We previously identified plasma exosomes as functionally critical actors in intercellular communication and drivers of tumor progression. Here, we generated patient-derived organoids (PDOs) from breast tumor resections to model signaling within the tumor microenvironment (TME). Novel techniques and a short (1-week) culture preserved native tumor-infiltrating lymphocytes for the first time in breast tumor PDOs. After 3-day exosome treatment, we measured the impact of exosomal signaling on PDOs via single-cell RNA sequencing. Exosomes derived from Type 2 diabetic patient plasma significantly upregulated pathways associated with epithelial-to-mesenchymal transition, invasiveness, and cancer stemness, compared to non-diabetic exosome controls. Intratumoral heterogeneity and immune evasion increased in the diabetic context, consistent with enhanced tumor aggressiveness and metastatic potential of these PDOs. Our model of systemic metabolic dysregulation and perturbed transcriptional networks enhances understanding of dynamic interactions within the TME in obesity-driven diabetes and offers new insights into novel exosomal communication.

Trastuzumab deruxtecan (T-DXd) is approved for HER2-low (HER2 immunohistochemistry (IHC)1+ or 2+ with non-amplified in situ hybridization (ISH)), but not HER2-0 (IHC 0) metastatic breast cancer. The impact of repeat biopsies (Bxs) in identifying new potential candidates with triple negative breast cancer (TNBC) for T-DXd treatment remains unknown. 512 consecutive patients with TNBC at diagnosis were included in the study cohort. Bxs were categorized as core, surgical, or metastatic based on the timing and method of biopsy (Bx) acquisition, and the total number of Bxs was determined for each patient. Additionally, matched biopsies were identified, and the rate of discordance in HER2 status was calculated. The proportion of patients with at least one HER2-low result increased as the number of successive Bxs increased [59%, 73%, 83%, 83%, and 100% when 1 (196 patients), 2 (231 patients), 3 (48 patients), 4 (29 patients), and ≥ 5 (8 patients) Bxs were obtained, respectively]. Among patients without a prior HER2-low result, approximately one-third demonstrated HER2-low status with each additional successive Bx. HER2 status exhibited variability between matched Bxs, with observed discordance rates of 26%, 44%, and 33% between matched core-surgical, early-metastatic, and two metastatic matched Bxs, respectively. Our findings indicate that HER2 status can vary between different Bxs taken during the disease course of patients with TNBC with the highest discordance rate observed between the primary and metastatic Bxs. For patients with metastastic HER2-0 TNBC, repeat Bxs can increase the chance of obtaining a HER2-low result, thereby offering patients a promising therapeutic option.

Discrimination can contribute to worse health outcomes, but its prevalence in breast cancer is not well studied. We aimed to understand how women with stage I-III breast cancer faced discrimination in health care and everyday settings through the Everyday Discrimination Scale, cross-sectional survey. 296 women, 178 (60%) Non-Hispanic White (NHW), 76 (26%) Non-Hispanic Black (NHB), and 42 (14%) Hispanic participated. NHB women reported significantly more discrimination in everyday life compared to NHW women (score 20.1 vs 16.1, p < 0.001) and Hispanic women (score 20.1 vs 16.0, p < 0.001). In the health care setting, NHB had statistically more frequent reports of being ignored (23.7% vs. 5.6%), treated with less respect (21.1% vs. 7.3%), and treated with less courtesy (18.7% vs. 6.2%; all P = < 0.001) when compared to NHW women. NHB women experience a higher degree of discrimination both inside and outside of health care. Further research to understand discrimination on breast cancer outcomes is warranted.

Discrimination can contribute to worse health outcomes, but its prevalence in breast cancer is not well studied. We aimed to understand how women with stage I-III breast cancer faced discrimination in health care and everyday settings through a cross-sectional survey. 296 women, 178 (60%) Non-Hispanic White (NHW), 76 (26%) Non-Hispanic Black (NHB), and 42 (14%) Hispanic participated. NHB women reported significantly more discrimination in everyday life compared to NHW women (score 20.1 vs 16.1, p<.001) and Hispanic women (score 20.1 vs 16.0, p<.001). In the health care setting, NHB had statistically more frequent reports of being ignored (23.7% vs. 5.6%), treated with less respect (21.1% vs. 7.3%), and treated with less courtesy (18.7% vs. 6.2%; all P=<.001) when compared to NHW women. NHB women experience a higher degree of discrimination both inside and outside of health care. Further research to understand discrimination on breast cancer outcomes is warranted.

PURPOSE/OBJECTIVE:Cyclin-dependent kinase (CDK) 4/6 inhibitors (CDK4/6is) are an important component of treatment for hormone receptor-positive/human epidermal growth factor receptor 2-negative (HER2-) metastatic breast cancer (MBC), but it is not known if patients might derive benefit from continuation of CDK4/6i with endocrine therapy beyond initial tumor progression or if the addition of checkpoint inhibitor therapy has value in this setting. METHODS:The randomized multicenter phase II PACE trial enrolled patients with hormone receptor-positive/HER2- MBC whose disease had progressed on previous CDK4/6i and aromatase inhibitor (AI) therapy. Patients were randomly assigned 1:2:1 to receive fulvestrant (F), fulvestrant plus palbociclib (F + P), or fulvestrant plus palbociclib and avelumab (F + P + A). The primary end point was investigator-assessed progression-free survival (PFS) in patients treated with F versus F + P. RESULTS:alterations. CONCLUSION/CONCLUSIONS:The addition of palbociclib to fulvestrant did not improve PFS versus fulvestrant alone among patients with hormone receptor-positive/HER2- MBC whose disease had progressed on a previous CDK4/6i plus AI. The increased PFS seen with the addition of avelumab warrants further investigation in this patient population.

UNLABELLED:(72h). EMT, proliferation and angiogenesis were elevated in IR vs. control and IS. Brain metastases showed more mesenchymal morphology and EMT enrichment in the IR group. MiR-145a-3p is highly differentially expressed between IS and IR, and potentially regulates metastasis. SIGNIFICANCE/UNASSIGNED:IR adipocyte exosomes modify TME, increase EMT and promote metastasis to distant organs, likely through miRNA pathways. We suggest metabolic diseases such as T2D reshape the TME, promoting metastasis and decreasing survival. Therefore, TNBC patients with T2D should be closely monitored for metastasis, with metabolic medications considered.