Faculty Bibliography

Advancements in molecular profiling and endocrine therapy (ET) have led to more focused clinical attention on precision medicine. These advances have expanded our understanding of breast cancer (BC) pathogenesis and hold promising implications for the future of therapy. The estrogen receptor-α is a predominant endocrine regulatory protein in the breast and in estrogen-induced BC. Successful targeting of proteins and genes within estrogen receptor (ER) nuclear and nonnuclear pathways remains a clinical goal. Several classes of antiestrogenic agents are available for patients with early, advanced, or metastatic BC, including selective ER modulators, aromatase inhibitors, and a selective ER degrader. Clinical development is focused upon characterizing the efficacy and tolerability of inhibitors that target the phosphatidylinositol 3 kinase (PI3K)/akt murine thymoma viral oncogene (AKT)/mammalian target of rapamycin inhibitor (mTOR) signaling pathway or the cyclin-dependent kinase 4/6 (CDK4/6) cell cycle pathway in women with hormone receptor-positive, human epidermal growth receptor 2-negative BC who have demonstrated disease recurrence or progression. De novo and acquired resistance remain a major challenge for women with BC receiving antiestrogenic therapy. Therefore, sequential combination of targeted ET is preferred in these patients, and the ever-increasing understanding of resistance mechanisms may better inform the selection of future therapy. This review describes the intricate roles of the PI3K/AKT/mTOR and CDK4/6 pathways in intracellular signaling and the use of endocrine and endocrine-based combination therapy in BC.

PURPOSE OF REVIEW:The treatment landscape for many cancers has dramatically changed with the development of checkpoint inhibitors. This article will review the literature concerning the use of checkpoint inhibitors in breast cancer. RECENT FINDINGS:The histological subtype of BC with the strongest signal of efficacy has been triple-negative breast cancer (TNBC). Early trials of single-agent checkpoint inhibitors did not demonstrate a uniformly positive signal. Clinical studies suggest response rates between 5 and 10% in pretreated patients and roughly 20-25% for untreated advanced TNBC. However, in the small subset of patients who do respond, the response is often durable. More encouraging results have been reported with their use in combination with chemotherapy in the neoadjuvant setting. Larger phase III studies are underway to confirm these earlier findings. An immune-directed therapeutic approach for the management of BC is underway, and it is likely that combination therapy will be required to achieve a level of efficacy worthy of use in the BC treatment paradigm. These agents are not without both economic and clinical toxicity; therefore, it is imperative that we identify patients most likely to benefit from these therapies through well-designed biologically plausible clinical studies and by evaluating novel combinatorial approaches with informative biomarker driven correlative studies.

Purpose: We profiled circulating tumor cells (CTCs) to study the biology of blood-borne metastasis and to monitor biomarker status in metastatic breast cancer (MBC).Methods: CTCs were isolated from 105 patients with MBC using EPCAM-based immunomagnetic enrichment and fluorescence-activated cells sorting (IE/FACS), 28 of whom had serial CTC analysis (74 samples, 2-5 time points). CTCs were subjected to microfluidic-based multiplex QPCR array of 64 cancer-related genes (n = 151) and genome-wide copy-number analysis by array comparative genomic hybridization (aCGH; n = 49).Results: Combined transcriptional and genomic profiling showed that CTCs were 26% ESR1^-ERBB2^-, 48% ESR1⁺ERBB2^-, and 27% ERBB2⁺ Serial testing showed that ERBB2 status was more stable over time compared with ESR1 and proliferation (MKI67) status. While cell-to-cell heterogeneity was observed at the single-cell level, with increasingly stable expression in larger pools, patient-specific CTC expression "fingerprints" were also observed. CTC copy-number profiles clustered into three groups based on the extent of genomic aberrations and the presence of large chromosomal imbalances. Comparative analysis showed discordance in ESR1/ER (27%) and ERBB2/HER2 (23%) status between CTCs and matched primary tumors. CTCs in 65% of the patients were considered to have low proliferation potential. Patients who harbored CTCs with high proliferation (MKI67) status had significantly reduced progression-free survival (P = 0.0011) and overall survival (P = 0.0095) compared with patients with low proliferative CTCs.Conclusions: We demonstrate an approach for complete isolation of EPCAM-positive CTCs and downstream comprehensive transcriptional/genomic characterization to examine the biology and assess breast cancer biomarkers in these cells over time. Clin Cancer Res; 24(6); 1486-99. ©2018 AACR.

BACKGROUND:The 21-gene recurrence score (RS) assay determines the benefit of adding chemotherapy to endocrine therapy for patients with early stage, estrogen receptor (ER)-positive, HER2-negative breast cancer. The RS risk groups predict the likelihood of distant recurrence and have recently been associated with an increased risk of locoregional recurrence (LRR). This study analyzed clinicopathologic features of patients with low RS and LRR. METHODS:In our institutional database, we identified 1396 consecutive female patients with lymph node negative, ER+/HER2- invasive breast carcinoma and low RS (<18) results, treated at our center from 2008 to 2013. We collected data on clinicopathologic features, treatment and outcome. RESULTS:The median patient age was 57 years (range 22-90). The median tumor size was 1.2 cm (range 0.3-5.8). Overall, 66.6% (930/1396) women were treated with breast conserving surgery (BCS) and radiation therapy, 3.4% (48/1396) with BCS alone, 29.7% (414/1396) with total mastectomy, and 0.3% (4/1396) with total mastectomy and radiation therapy. Most patients (84.8%; 1184/1396) received endocrine therapy alone, 12.1% (169/1396) were treated with chemotherapy plus endocrine therapy, and only 3.1% (43/1396) received no systemic therapy. At a median follow-up of 52 months, 0.9% (13/1396) of patients developed LRR. Sites of LRR included the ipsilateral breast (n = 8), chest wall (n = 3), axillary node (n = 1), and internal mammary node (n = 1). All patients with LRR had negative resection margins at the initial surgery. The rate of LRR in patients treated with adjuvant endocrine therapy alone was 0.7% (8/1184). All eight patients received standard local treatment. Three patients had lymphovascular invasion but no other significant risk factors for LRR were identified. CONCLUSIONS:Our study of node negative, ER+/HER2- breast cancer patients with low RS observed extremely low rates of LRR: 0.9% (13/1396) in the whole cohort and 0.7% (8/1184) in patients treated with endocrine therapy alone. As the largest series to date, we report detailed clinicopathologic data and clinical outcomes of this cohort and provide a comprehensive characterization of patients who developed LRR.

Purpose of the review/UNASSIGNED:To understand the evidence for extending adjuvant aromatase inhibitor (AI) therapy from 5 to 10 years in post-menopausal women with hormone receptor positive (HR+) breast cancer. Recent findings/UNASSIGNED:Multiple large trials have investigated this question. The two trials most representative of the dilemma faced in clinical practice are the MA.17R and NSABP-B42 trials, which both investigated the benefit of continuing versus stopping AI therapy beyond 5 years. Both trials showed that extended AI therapy led to a reduction in new or recurrent breast cancers, but had no effect on survival outcomes when death from any cause was included. Summary/UNASSIGNED:The decision to extend AI therapy beyond 5 years remains a personalized one based on a discussion of the projected risk of recurrence, the expected benefits of prolonged AI treatment, and the patient's ability to tolerate side effects so that quality of life is preserved.

OBJECTIVE: Bevacizumab, a monoclonal antibody to VEGF, has shown efficacy in ovarian, cervical and endometrial cancer in addition to several other solid tumors. Serious side effects include hypertension, proteinuria, bowel perforation, and thrombosis. We tested the hypothesis that genetic variation in hypertension-associated genes is associated with bevacizumab-induced hypertension (BIH). METHODS: Patients with solid tumors treated with bevacizumab in combination with other therapy were identified from six clinical trials. Haplotype-tagging (ht) SNPs for 10 candidate genes associated with hypertension were identified through the International Hapmap Project. Germline DNA was genotyped for 103 htSNPs using mass spectrometry. Bevacizumab toxicities were identified from clinical trial reports. Haplotypes were reconstructed from diploid genotyping data and frequencies were compared using standard two-sided statistical tests. RESULTS: The study included 114 patients with breast, lung, ovarian, or other cancers, of whom 38 developed BIH. WNK1, KLKB1, and GRK4 were found to contain single loci associated with BIH. Haplotype analysis of WNK1, KLKB1, and GRK4 identified risk haplotypes in each gene associated with grade 3/4 BIH. A composite risk model was created based on these haplotypes. Patients with the highest risk score were the most likely to develop grade 3/4 BIH (OR=6.45; P=0.005; 95%CI, 1.86-22.39). CONCLUSIONS: We concluded that genetic variation in WNK1, KLKB1, and GRK4 may be associated with BIH. These genes are biologically plausible mediators due to their role in blood pressure control, regulating sodium homeostasis and vascular tone. This preliminary risk model performed better than population-based risk models and when further validated may help risk-stratify patients for BIH prior to initiating therapy.

BACKGROUND/PURPOSE/OBJECTIVE:The 21-gene recurrence score (RS) assay evaluates the likelihood of distant recurrence and benefit of chemotherapy in lymph node-negative, estrogen receptor (ER)-positive, HER2-negative breast cancer patients. The RS categories are associated with the risk of locoregional recurrence (LRR) in some, but not all studies. METHODS:We reviewed the institutional database to identify consecutive female patients with node-negative, ER+/HER2- breast carcinoma tested for the 21-gene RS assay and treated at our center from 2008 to 2013. We collected data on clinicopathologic features, treatment, and outcome. Statistical analysis was performed using SAS version 9.4 or R version 3.3.2. RESULTS:Of 2326 patients, 60% (1394) were in the low RS group, 33.4% (777) in the intermediate RS group, and 6.6% (155) in the high RS group. Median follow-up was 53 months. A total of 44 LRRs were observed, with a cumulative incidence of 0.17% at 12 months and 1.6% at 48 months. The cumulative incidence of LRR at 48 months was 0.84%, 2.72% and 2.80% for low, intermediate, and high RS groups, respectively (p < 0.01). Univariate analysis showed that the risk of LRR was associated with the RS categories (p < 0.01), T stage (p < 0.01) and lymphovascular invasion (LVI) (p = 0.009). There was no difference in LRR rates by initial local treatment (total mastectomy vs. breast-conserving surgery plus radiation therapy). The RS remained significantly associated with LRR after adjusting for LVI and T stage. Compared to patients with low RS, the risk of LRR was increased more than 4-fold (hazard ratio: 4.61, 95% CI 1.90-11.19, p < 0.01), and 3-fold (hazard ratio: 2.81, 95% CI 1.41-5.56, p < 0.01) for high and intermediate risk categories, respectively. CONCLUSIONS:Our study confirms that RS is significantly associated with the risk of LRR in node-negative, ER+/HER2- breast cancer patients. Our findings suggest that in addition to its value for prognostic stage grouping and decision-making regarding adjuvant systemic therapy, the role of the RS in identifying patients not requiring radiotherapy should be studied.