Pathogenesis, prevention, diagnosis and treatment of breast cancer

Women of sub-Saharan African descent have disproportionately higher incidence of triple-negative breast cancer (TNBC) and TNBC-specific mortality across all populations. Population studies show racial differences in TNBC biology, including higher prevalence of basal-like and quadruple-negative subtypes in African Americans (AA). However, previous investigations relied on self-reported race (SRR) of primarily U.S. populations. Due to heterogeneous genetic admixture and biological consequences of social determinants, the true association of African ancestry with TNBC biology is unclear. To address this, we conducted RNA sequencing on an international cohort of AAs, as well as West and East Africans with TNBC. Using comprehensive genetic ancestry estimation in this African-enriched cohort, we found expression of 613 genes associated with African ancestry and 2,000+ associated with regional African ancestry. A subset of African-associated genes also showed differences in normal breast tissue. Pathway enrichment and deconvolution of tumor cellular composition revealed that tumor-associated immunologic profiles are distinct in patients of African descent. Significance: Our comprehensive ancestry quantification process revealed that ancestry-associated gene expression profiles in TNBC include population-level distinctions in immunologic landscapes. These differences may explain some differences in race–group clinical outcomes. This study shows the first definitive link between African ancestry and the TNBC immunologic landscape, from an African-enriched international multiethnic cohort. See related commentary by Hamilton et al., p. 2496. This article is highlighted in the In This Issue feature, p. 2483

Aims: To investigate cardiovascular (CV) safety and event rates for dapagliflozin versus other glucose‐lowering drugs (GLDs) in a real‐world type 2 diabetes population after applying the main inclusion criteria and outcomes from the DECLARE‐TIMI 58 study. Methods: Patients with new initiation of dapagliflozin and/or other GLDs were identified in Swedish nationwide healthcare registries for the period 2013 to 2016. Patients were included if they met the main DECLARE‐TIMI 58 inclusion criteria: age ≥40 years and established CV disease or presence of multiple‐risk factors, e.g. men aged ≥55 years and women aged ≥60 years with hypertension or dyslipidaemia. Propensity scores for the likelihood of dapagliflozin initiation were calculated, then 1:3 matching was carried out. DECLARE‐TIMI 58 outcomes were hospitalization for heart failure (HHF) or CV‐specific mortality, and major adverse CV events (MACE; CV‐specific mortality, myocardial infarction, or stroke). Cox survival models were used to estimate hazard ratios (HRs). Results: After matching, a total of 28 408 new‐users of dapagliflozin and/or other GLDs were identified, forming the population for the present study (henceforth referred to as the DECLARE‐like cohort. The mean age of this cohort was 66 years, and 34% had established CV disease. Dapagliflozin was associated with 21% lower risk of HHF or CV mortality versus other GLDs (HR 0.79, 95% confidence interval [CI] 0.69‐0.92) and had no significant association with MACE (HR 0.90, 95% CI 0.79‐1.03). HHF and CV mortality risks, separately, were lower at HR 0.79 (95% CI 0.67‐0.93) and HR 0.75 (95% CI 0.57‐0.97), respectively. Non‐significant associations were seen for myocardial infarction and stroke: HR 0.91 (95% CI 0.74‐1.11) and HR 1.06 (95% CI 0.87‐1.30), respectively. Conclusion: In a real‐world population similar to those included in the DECLARE‐TIMI 58 study, dapagliflozin was safe with regard to CV outcomes and resulted in lower event rates of HHF and CV mortality versus other GLDs.

Invasive breast cancer tends to metastasize to lymph nodes and systemic sites. The management of metastasis has evolved by focusing on controlling the growth of the disease in the breast/chest wall, and at metastatic sites, initially by surgery alone, then by a combination of surgery with radiation, and later by adding systemic treatments in the form of chemotherapy, hormone manipulation, targeted therapy, immunotherapy and other treatments aimed at inhibiting the proliferation of cancer cells. It would be valuable for us to know how breast cancer metastasizes; such knowledge would likely encourage the development of therapies that focus on mechanisms of metastasis and might even allow us to avoid toxic therapies that are currently used for this disease. For example, if we had a drug that targeted a gene that is critical for metastasis, we might even be able to cure a vast majority of patients with breast cancer. By bringing together scientists with expertise in molecular aspects of breast cancer metastasis, and those with expertise in the mechanical aspects of metastasis, this paper probes interesting aspects of the metastasis cascade, further enlightening us in our efforts to improve the outcome from breast cancer treatments.