Phase III Randomized, Placebo-Controlled Trial of Endocrine Therapy ± 1 Year of Everolimus in Patients With High-Risk, Hormone Receptor-Positive, Early-Stage Breast Cancer.

PURPOSE: Phosphatidylinositol 3-kinase/AKT-serine threonine kinase/mammalian target of rapamycin (mTOR) pathway abnormalities contribute to endocrine resistance. Everolimus, an mTOR inhibitor, improved progression-free survival in hormone receptor-positive metastatic breast cancer (BC) when combined with endocrine therapy (ET). In this phase III randomized, placebo-controlled trial, we assessed the efficacy of everolimus + ET as adjuvant therapy in high-risk, hormone receptor-positive, human epidermal growth factor receptor 2-negative BC after adjuvant/neoadjuvant chemotherapy. METHODS: Patients were randomly assigned 1:1 to physician's choice ET and 1 year of everolimus (10 mg orally once daily) or placebo stratified by risk group. The primary end point was invasive disease-free survival (IDFS) evaluated by a stratified log-rank test with the hazard ratio (HR) estimated by Cox regression. Subset analyses included preplanned evaluation by risk group and exploratory analyses by menopausal status and age. Secondary end points included overall survival (OS) and safety. Everolimus did not improve IDFS/OS when added to ET in patients with early-stage high-risk, hormone receptor-positive BC. RESULTS: One thousand and nine hundred thirty-nine patients were randomly assigned with 1,792 eligible for analysis. Overall, no benefit of everolimus was seen for IDFS (HR, 0.94 [95% CI, 0.77 to 1.14]) or OS (HR, 0.97 [95% CI, 0.75 to 1.26]). The assumption of proportional hazards was not met suggesting significant variability in the HR over time since the start of treatment. In an unplanned subgroup analysis among postmenopausal patients (N = 1,221), no difference in IDFS (HR, 1.08 [95% CI, 0.86 to 1.36]) or OS (HR, 1.19 [95% CI, 0.89 to 1.60]) was seen. In premenopausal patients (N = 571), everolimus improved both IDFS (HR, 0.64 [95% CI, 0.44 to 0.94]) and OS (HR, 0.49 [95% CI, 0.28 to 0.86]). Treatment completion rates were lower in the everolimus arm compared with placebo (48% v 73%) with higher grade 3 and 4 adverse events (35% v 7%). CONCLUSION: One year of adjuvant everolimus + ET did not improve overall outcomes. Subset analysis suggests mTOR inhibition as a possible target for patients who remain premenopausal after chemotherapy.

Circulating tumor cells et al.: towards a comprehensive liquid biopsy approach in breast cancer.

Liquid biopsy has emerged as a crucial tool in managing breast cancer (BC) patients, offering a minimally invasive approach to detect circulating tumor biomarkers. Until recently, the majority of the studies in BC focused on evaluating a single liquid biopsy analyte, primarily circulating tumor DNA and circulating tumor cells (CTCs). Despite the proven prognostic and predictive value of CTCs, their low abundance when detected using enrichment methods, especially in the early stages, poses a significant challenge. It is becoming evident that combining diverse circulating biomarkers, each representing different facets of tumor biology, has the potential to enhance the management of patients with BC. This article emphasizes the importance of considering these biomarkers as complementary/synergistic rather than competitive, recognizing their ability to contribute to a comprehensive disease profile. The review provides an overview of the clinical significance of simultaneously analyzing CTCs and other biomarkers, including cell-free circulating DNA, extracellular vesicles, non-canonical CTCs, cell-free RNAs, and non-malignant cells. Such a comprehensive liquid biopsy approach holds promise not only in BC but also in other cancer types, offering opportunities for early detection, prognostication, and therapy monitoring. However, addressing associated challenges, such as refining detection methods and establishing standardized protocols, is crucial for realizing the full potential of liquid biopsy in transforming our understanding and approach to BC. As the field evolves, collaborative efforts will be instrumental in unlocking the revolutionary impact of liquid biopsy in BC research and management.

Randomized Phase II Trial of Endocrine Therapy With or Without Ribociclib After Progression on Cyclin-Dependent Kinase 4/6 Inhibition in Hormone Receptor-Positive, Human Epidermal Growth Factor Receptor 2-Negative Metastatic Breast Cancer: MAINTAIN Trial.

PURPOSE: Cyclin-dependent kinase 4/6 inhibitor (CDK4/6i) with endocrine therapy (ET) improves progression-free survival (PFS) and overall survival (OS) in hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) metastatic breast cancer (MBC). Although preclinical and clinical data demonstrate a benefit in changing ET and continuing a CDK4/6i at progression, no randomized prospective trials have evaluated this approach. METHODS: In this investigator-initiated, phase II, double-blind placebo-controlled trial in patients with HR+/HER2- MBC whose cancer progressed during ET and CDK4/6i, participants switched ET (fulvestrant or exemestane) from ET used pre-random assignment and randomly assigned 1:1 to the CDK4/6i ribociclib versus placebo. PFS was the primary end point, defined as time from random assignment to disease progression or death. Assuming a median PFS of 3.8 months with placebo, we had 80% power to detect a hazard ratio (HR) of 0.58 (corresponding to a median PFS of at least 6.5 months with ribociclib) with 120 patients randomly assigned using a one-sided log-rank test and significance level set at 2.5%. RESULTS: Of the 119 randomly assigned participants, 103 (86.5%) previously received palbociclib and 14 participants received ribociclib (11.7%). There was a statistically significant PFS improvement for patients randomly assigned to switched ET plus ribociclib (median, 5.29 months; 95% CI, 3.02 to 8.12 months) versus switched ET plus placebo (median, 2.76 months; 95% CI, 2.66 to 3.25 months) HR, 0.57 (95% CI, 0.39 to 0.85); P = .006. At 6 and 12 months, the PFS rate was 41.2% and 24.6% with ribociclib, respectively, compared with 23.9% and 7.4% with placebo. CONCLUSION: In this randomized trial, there was a significant PFS benefit for patients with HR+/HER2- MBC who switched ET and received ribociclib compared with placebo after previous CDK4/6i and different ET.

Benefit of adjuvant chemotherapy in node-negative T1a versus T1b and T1c triple-negative breast cancer.

PURPOSE: National comprehensive cancer network guidelines recommend delivery of adjuvant chemotherapy in node-negative triple-negative breast cancer (TNBC) if the tumor is > 1 cm and consideration of adjuvant chemotherapy for T1b but not T1a disease. These recommendations are based upon sparse data on the role of adjuvant chemotherapy in T1a and T1b node-negative TNBC. Our objective was to clarify the benefits of chemotherapy for patients with T1N0 TNBC, stratified by tumor size. METHODS: We performed a retrospective analysis of survival outcomes of TNBC patients at two academic institutions in the United States from 1999 to 2018. Primary tumor size, histology, and nodal status were based upon surgical pathology. The Kaplan-Meier plot and 5-year unadjusted survival probability were evaluated. RESULTS: Among 282 T1N0 TNBC cases, the status of adjuvant chemotherapy was known for 258. Mean follow-up was 5.3 years. Adjuvant chemotherapy was delivered to 30.5% of T1a, 64.7% T1b, and 83.9% T1c (p < 0.0001). On multivariable analysis, factors associated with delivery of adjuvant chemotherapy were tumor size and grade 3 disease. Improved overall survival was associated with use of chemotherapy in patients with T1c disease (93.2% vs. 75.2% p = 0.008) but not T1a (100% vs. 100% p = 0.3778) or T1b (100% vs. 95.8% p = 0.2362) disease. CONCLUSION: Our data support current guidelines indicating benefit from adjuvant chemotherapy in node-negative TNBC associated with T1c tumors but excellent outcomes were observed in the cases of T1a and T1b disease, regardless of whether adjuvant chemotherapy was delivered.

Facts and Perspectives: Implications of tumor glycolysis on immunotherapy response in triple negative breast cancer.

Triple negative breast cancer (TNBC) is an aggressive disease that is difficult to treat and portends a poor prognosis in many patients. Recent efforts to implement immune checkpoint inhibitors into the treatment landscape of TNBC have led to improved outcomes in a subset of patients both in the early stage and metastatic settings. However, a large portion of patients with TNBC remain resistant to immune checkpoint inhibitors and have limited treatment options beyond cytotoxic chemotherapy. The interplay between the anti-tumor immune response and tumor metabolism contributes to immunotherapy response in the preclinical setting, and likely in the clinical setting as well. Specifically, tumor glycolysis and lactate production influence the tumor immune microenvironment through creation of metabolic competition with infiltrating immune cells, which impacts response to immune checkpoint blockade. In this review, we will focus on how glucose metabolism within TNBC tumors influences the response to immune checkpoint blockade and potential ways of harnessing this information to improve clinical outcomes.

Alterations of the 70 kDa heat shock protein (HSP70) and sequestosome-1 (p62) in women with breast cancer.

Peripheral blood mononuclear cells (PBMCs) respond to altered physiological conditions to alleviate the threat. Production of the 70 kDa heat shock protein (HSP70) is up-regulated to protect proteins from degradation. Sequestosome-1 (p62) binds to altered proteins and the p62-protein complex is degraded by autophagy. P62 is also a regulator of intracellular kinase activity and cell differentiation. We hypothesized that the PBMC response to a malignant breast mass involves elevated production of HSP70 and a decrease in intracellular p62. In this study 46 women had their breast mass excised. PBMCs were isolated and intracellular levels of HSP70 and p62 were quantitated by ELISA. Differences between women with a benign or malignant breast mass were determined. A breast malignancy was diagnosed in 38 women (82.6%) while 8 had a benign lesion. Mean intracellular HSP70 levels were 79.3 ng/ml in PBMCs from women with a malignant lesion as opposed to 44.2 ng/ml in controls (p = 0.04). The mean PBMC p62 level was 2.3 ng/ml in women with a benign breast lesion as opposed to 0.6 ng/ml in those with breast cancer (p < 0.001). Mean p62 levels were lowest in women with invasive carcinoma and a positive lymph node biopsy when compared to those with in-situ carcinoma or absence of lymphadenopathy, respectively. Intracellular HSP70 and p62 levels in PBMCs differ between women with a malignant or benign breast lesion. These measurements may be of value in the preoperative triage of women with a breast mass.

Tetrathiomolybdate (TM)-associated copper depletion influences collagen remodeling and immune response in the pre-metastatic niche of breast cancer.

Tetrathiomolybdate (TM) is a novel, copper-depleting compound associated with promising survival in a phase II study of patients with high-risk and triple-negative breast cancer. We sought to elucidate the mechanism of TM by exploring its effects on collagen processing and immune function in the tumor microenvironment (TME). Using an exploratory cohort, we identified markers of collagen processing (LOXL2, PRO-C3, C6M, and C1M) that differed between those with breast cancer versus controls. We measured these collagen biomarkers in TM-treated patients on the phase II study and detected evidence of decreased collagen cross-linking and increased degradation over formation in those without disease compared to those who experienced disease progression. Preclinical studies revealed decreased collagen deposition, lower levels of myeloid-derived suppressor cells, and higher CD4+ T-cell infiltration in TM-treated mice compared with controls. This study reveals novel mechanisms of TM targeting the TME and immune response with potential applications across cancer types.

Phase I/II trial of ruxolitinib in combination with trastuzumab in metastatic HER2 positive breast cancer.

PURPOSE: Preclinical data demonstrate STAT3 as an important regulator in HER2+ tumors, and disruption of the IL6-JAK2-STAT-S100A8/S100A9 signaling cascade reduces HER2+ cell viability. Ruxolitinib is an FDA approved inhibitor of JAK1 and JAK2. We performed a phase I/II trial investigating the safety and efficacy of the combination of trastuzumab and ruxolitinib in patients with trastuzumab-resistant metastatic HER2+ breast cancer. METHODS: Patients with metastatic HER2+ breast cancer progressing on at least 2 lines of HER2-directed therapy were eligible. The phase I portion determined the tolerable dose of ruxolitinib in combination with trastuzumab. The primary objective of the phase II was to assess the progression free survival (PFS) of the combination of ruxolitinib plus trastuzumab compared to historical control. RESULTS: Twenty-eight patients were enrolled, with a median number of prior therapies of 4.5. Ruxolitinib 25 mg twice daily was the recommended phase II dose with no dose limiting toxicities (DLTs). Of 26 evaluable patients in phase II, the median PFS was 8.3 weeks (95% CI 7.1, 13.9). Among the 14 patients with measurable disease, 1 patient had a partial response and 4 patients had stable disease. Most of the adverse events were hematologic. CONCLUSION: While well tolerated with a strong preclinical rationale, the combination of ruxolitinib and trastuzumab did not lead to an improvement in PFS compared to historical control in patients with trastuzumab-resistant metastatic HER2+ breast cancer.

Eribulin Plus Pembrolizumab in Patients with Metastatic Triple-Negative Breast Cancer (ENHANCE 1): A Phase Ib/II Study.

PURPOSE: As monotherapies, eribulin (chemotherapy) and pembrolizumab (immunotherapy) have shown promise for patients with metastatic triple-negative breast cancer (mTNBC). This phase Ib/II study examined eribulin plus pembrolizumab as a potential mTNBC treatment in first-line and later-line settings. PATIENTS AND METHODS: In this open-label, single-arm, phase Ib/II study, eligible patients had mTNBC, measurable disease, and ≤2 prior systemic anticancer therapies in the metastatic setting. Patients were enrolled by number of prior systemic anticancer therapies (stratum 1: 0 vs stratum 2: 1-2) in the metastatic setting and further analyzed by tumor programmed death-ligand 1 (PD-L1) expression status. All patients received intravenous eribulin 1.4 mg/m2 on day 1 and day 8, plus intravenous pembrolizumab 200 mg on day 1, of 21-day cycles. The primary objectives were the safety, tolerability, and objective response rate (ORR) of this combination. RESULTS: The study included 167 patients (phase Ib, n = 7; phase II, n = 160). The most common treatment-emergent adverse events were fatigue (66%), nausea (58%), peripheral sensory neuropathy (41%), alopecia (40%), and constipation (37%). ORRs were 25.8% [95% confidence interval (CI): 15.8-38.0] for stratum 1 (n = 66) and 21.8% (95% CI: 14.2-31.1) for stratum 2 (n = 101). Patients with PD-L1-positive tumors (combined positive score ≥1) had numerically higher ORR than those with PD-L1-negative tumors, particularly in stratum 1 [stratum 1: 34.5% (95% CI: 17.9-54.3) vs 16.1% (95% CI: 5.5-33.7); stratum 2, 24.4% (95% CI: 12.9-39.5) vs 18.2% (95% CI: 8.2-32.7)]. CONCLUSIONS: Eribulin plus pembrolizumab was generally well tolerated and showed promising antitumor activity in mTNBC. Efficacy outcomes appeared influenced by line of therapy and PD-L1 status.

Three-dimensional growth of breast cancer cells potentiates the anti-tumor effects of unacylated ghrelin and AZP-531.

Breast cancer is the most common type of cancer in women and notwithstanding important therapeutic advances, remains the second leading cause of cancer-related death. Despite extensive research relating to the hormone ghrelin, responsible for the stimulation of growth hormone release and appetite, little is known of the effects of its unacylated form, especially in cancer. The present study aimed to characterize effects of unacylated ghrelin on breast cancer cells, define its mechanism of action, and explore the therapeutic potential of unacylated ghrelin or analog AZP-531. We report potent anti-tumor effects of unacylated ghrelin, dependent on cells being cultured in 3D in a biologically-relevant extracellular matrix. The mechanism of unacylated ghrelin-mediated growth inhibition involves activation of Gαi and suppression of MAPK signaling. AZP-531 also suppresses the growth of breast cancer cells in vitro and in xenografts, and may be a novel approach for the safe and effective treatment of breast cancer.

Akt Inhibition Is Associated With Favorable Immune Profile Changes Within the Tumor Microenvironment of Hormone Receptor Positive, HER2 Negative Breast Cancer.

Background: The PI3K/Akt/mTOR pathway in part impacts tumorigenesis through modulation of host immune activity. To assess the effects of Akt inhibition on the tumor micro-environment (TME), we analyzed tumor tissue from patients with operable hormone receptor positive, HER2 negative breast cancer (BC) treated on a presurgical trial with the Akt inhibitor MK-2206. Methods: Quantitative multiplex immunofluorescence (qmIF) was performed using CD3, CD8, CD4, FOXP3, CD68, and pancytokeratin on biopsy and surgical specimens of MK-2206 and untreated, control patients. nanoString was performed on surgical specimens to assess mRNA expression from MK-2206-treated vs. control patients. Results: Increased CD3+CD8+ density was observed in post vs. pre-treatment tissue in the MK-2206-treated vs. control patients (87 vs. 0.2%, p < 0.05). MK-2206 was associated with greater expression of interferon signaling genes (e.g., IFI6, p < 0.05) and lower expression of myeloid genes (CD163, p < 0.05) on differential expression and gene set enrichment analyses. Greater expression of pro-apoptotic genes (e.g., BAD) were associated with MK-2206 treatment (p < 0.05). Conclusion: Akt inhibition in operable BC was associated with a favorable immune profile in the TME, including increased CD3+CD8+ density and greater expression of interferon genes. Additional studies are warranted, as this may provide rationale for combining Akt inhibition with immunotherapy.

Phase I Study of Veliparib on an Intermittent and Continuous Schedule in Combination with Carboplatin in Metastatic Breast Cancer: A Safety and [18F]-Fluorothymidine Positron Emission Tomography Biomarker Study.

BACKGROUND: Poly(ADP-ribose) polymerase inhibitors (PARPis) are U.S. Food and Drug Administration (FDA) approved for treatment of BRCA-mutated metastatic breast cancer. Furthermore, the BROCADE studies demonstrated benefit of adding an oral PARPi, veliparib, to carboplatin and paclitaxel in patients with metastatic breast cancer harboring BRCA mutation. Given multiple possible dosing schedules and the potential benefit of this regimen for patients with defective DNA repair beyond BRCA, we sought to find the recommended phase II dose (RP2D) and schedule of veliparib in combination with carboplatin in patients with advanced breast cancer, either triple-negative (TNBC) or hormone receptor (HR)-positive, human epidermal growth receptor 2 (HER2) negative with defective Fanconi anemia (FA) DNA-repair pathway based on FA triple staining immunofluorescence assay. MATERIALS AND METHODS: Patients received escalating doses of veliparib on a 7-, 14-, or 21-day schedule with carboplatin every 3 weeks. Patients underwent [18]fluoro-3'-deoxythymidine (18 FLT) positron emission tomography (PET) imaging. RESULTS: Forty-four patients (39 TNBC, 5 HR positive/HER2 negative with a defective FA pathway) received a median of 5 cycles (range 1-36). Observed dose-limiting toxicities were grade (G) 4 thrombocytopenia (n = 4), G4 neutropenia (n = 1), and G3 akathisia (n = 1). Common grade 3-4 toxicities included thrombocytopenia, lymphopenia, neutropenia, anemia, and fatigue. Of the 43 patients evaluable for response, 18.6% achieved partial response and 48.8% had stable disease. Median progression-free survival was 18.3 weeks. RP2D of veliparib was established at 250 mg twice daily on days 1-21 along with carboplatin at area under the curve 5. Patients with partial response had a significant drop in maximum standard uptake value (SUVmax ) of target lesions between baseline and early in cycle 1 based on 18 FLT-PET (day 7-21; ptrend = .006). CONCLUSION: The combination of continuous dosing of veliparib and every-3-week carboplatin demonstrated activity and an acceptable toxicity profile. Decrease in SUVmax on 18 FLT-PET scan during the first cycle of this therapy can identify patients who are likely to have a response. IMPLICATIONS FOR PRACTICE: The BROCADE studies suggest that breast cancer patients with BRCA mutation benefit from addition of veliparib to carboplatin plus paclitaxel. This study demonstrates that a higher dose of veliparib is tolerable and active in combination with carboplatin alone. With growing interest in imaging-based early response assessment, the authors demonstrate that decrease in [18]fluoro-3'-deoxythymidine positron emission tomography (FLT-PET) SUVmax during cycle 1 of therapy is associated with response. Collectively, this study established a safety profile of veliparib and carboplatin in advanced breast cancer while also providing additional data on the potential for FLT-PET imaging modality in monitoring therapy response.

Inhibition of EZH2 Catalytic Activity Selectively Targets a Metastatic Subpopulation in Triple-Negative Breast Cancer.

Epigenetic changes are increasingly being appreciated as key events in breast cancer progression. However, breast cancer subtype-specific epigenetic regulation remains poorly investigated. Here we report that EZH2 is a leading candidate of epigenetic modulators associated with the TNBC subtype and that it predicts poor overall survival in TNBC patients. We demonstrate that specific pharmacological or genetic inhibition of EZH2 catalytic activity impairs distant metastasis. We further define a specific EZH2high population with enhanced invasion, mammosphere formation, and metastatic potential that exhibits marked sensitivity to EZH2 inhibition. Mechanistically, EZH2 inhibition differentiates EZH2high basal cells to a luminal-like phenotype by derepressing GATA3 and renders them sensitive to endocrine therapy. Furthermore, dissection of human TNBC heterogeneity shows that EZH2high basal-like 1 and mesenchymal subtypes have exquisite sensitivity to EZH2 inhibition compared with the EZH2low luminal androgen receptor subtype. These preclinical findings provide a rationale for clinical development of EZH2 as a targeted therapy against TNBC metastasis.

Endocrine Therapy-related Endocrinopathies-Biology, Prevalence and Implications for the Management of Breast Cancer.

Nearly 270,000 new breast cancer cases are predicted to be diagnosed in the USA in 2019 with more than 70% being estrogen receptor positive and treated using endocrine therapy. The suppression of estrogen biosynthesis or action via the use of ovarian suppression, aromatase inhibitors and selective estrogen receptor modulators/degraders, respectively, is effective in approximately 70% of women. The systemic inhibition of estrogen during breast cancer treatment is also associated with side effects due to the important endocrine functions of this steroid hormone, including its role in the maintenance of energy homeostasis and bone health. The current work will present perspectives of the impact of endocrine therapy from the point of view of breast medical oncology, endocrinology, and basic science.

Integrative Molecular Analysis of Patients With Advanced and Metastatic Cancer.

PURPOSE: We developed a precision medicine program for patients with advanced cancer using integrative whole-exome sequencing and transcriptome analysis. PATIENTS AND METHODS: Five hundred fifteen patients with locally advanced/metastatic solid tumors were prospectively enrolled, and paired tumor/normal sequencing was performed. Seven hundred fifty-nine tumors from 515 patients were evaluated. RESULTS: Most frequent tumor types were prostate (19.4%), brain (16.5%), bladder (15.4%), and kidney cancer (9.2%). Most frequently altered genes were TP53 (33%), CDKN2A (11%), APC (10%), KTM2D (8%), PTEN (8%), and BRCA2 (8%). Pathogenic germline alterations were present in 10.7% of patients, most frequently CHEK2 (1.9%), BRCA1 (1.5%), BRCA2 (1.5%), and MSH6 (1.4%). Novel gene fusions were identified, including a RBM47-CDK12 fusion in a metastatic prostate cancer sample. The rate of clinically relevant alterations was 39% by whole-exome sequencing, which was improved by 16% by adding RNA sequencing. In patients with more than one sequenced tumor sample (n = 146), 84.62% of actionable mutations were concordant. CONCLUSION: Integrative analysis may uncover informative alterations for an advanced pan-cancer patient population. These alterations are consistent in spatially and temporally heterogeneous samples.

SETER/PR: a robust 18-gene predictor for sensitivity to endocrine therapy for metastatic breast cancer.

There is a clinical need to predict sensitivity of metastatic hormone receptor-positive and HER2-negative (HR+/HER2-) breast cancer to endocrine therapy, and targeted RNA sequencing (RNAseq) offers diagnostic potential to measure both transcriptional activity and functional mutation. We developed the SETER/PR index to measure gene expression microarray probe sets that were correlated with hormone receptors (ESR1 and PGR) and robust to preanalytical and analytical influences. We tested SETER/PR index in biopsies of metastastic HR+/HER2- breast cancer against the treatment outcomes in 140 patients. Then we customized the SETER/PR assay to measure 18 informative, 10 reference transcripts, and sequence the ligand-binding domain (LBD) of ESR1 using droplet-based targeted RNAseq, and tested that in residual RNA from 53 patients. Higher SETER/PR index in metastatic samples predicted longer PFS and OS when patients received endocrine therapy as next treatment, even after adjustment for clinical-pathologic risk factors (PFS: HR 0.534, 95% CI 0.299 to 0.955, p = 0.035; OS: HR 0.315, 95% CI 0.157 to 0.631, p = 0.001). Mutated ESR1 LBD was detected in 8/53 (15%) of metastases, involving 1-98% of ESR1 transcripts (all had high SETER/PR index). A signature based on probe sets with good preanalytical and analytical performance facilitated our customization of an accurate targeted RNAseq assay to measure both phenotype and genotype of ER-related transcription. Elevated SETER/PR was associated with prolonged sensitivity to endocrine therapy in patients with metastatic HR+/HER2- breast cancer, especially in the absence of mutated ESR1 transcript.

Phase I Trial of Veliparib, a Poly ADP Ribose Polymerase Inhibitor, Plus Metronomic Cyclophosphamide in Metastatic HER2-negative Breast Cancer.

BACKGROUND: Poly-ADP-ribose-polymerase is an essential nuclear enzyme, involved in base-excision repair of damaged DNA. Poly-ADP-ribose-polymerase inhibition sensitizes tumor cells to cytotoxic agents, which induce DNA damage, including cyclophosphamide (C), and metronomic dosing of C may optimize potential for synergy. METHODS: The primary objective of this phase I trial was to determine the safety and identify the recommended phase II dose of the combination of low-dose oral C (50, 75, 100, and 125 mg) once daily in combination with veliparib (V) (100, 200, and 300 mg) administered twice a day (BID) for 21-day cycles using a standard 3 + 3 design in patients with metastatic human epidermal growth factor receptor 2/neu-negative breast cancer. Dose-limiting toxicity was defined as any grade 3 non-hematologic toxicity or grade 4 thrombocytopenia/neutropenia occurring during cycle 1. RESULTS: A total of 31 patients were enrolled; 19 were treated with 50 mg of C and 12 were treated at higher doses (75, 100, or 125 mg), with V doses ranging from 50 to 300 mg BID. The recommended phase II dose of the combination was V 200 mg orally BID plus C 125 mg orally daily, with nausea and headache dose-limiting at higher V dose levels. Objective response or stable disease for at least 24 weeks occurred in 3 (43%) of 7 patients with known deleterious germline BRCA mutations and 2 (11%) of 19 patients with negative/unknown mutation status (P = .1). CONCLUSION: The combination of oral continuous dosing of V (200 mg orally BID) with metronomic C (50, 75, 100, and 125 mg daily) is well-tolerated and shows antitumor activity in patients with BRCA-mutation-associated metastatic human epidermal growth factor receptor 2/neu-negative breast cancer.

Therapeutic Advances and New Directions for Triple-Negative Breast Cancer.

Triple-negative breast cancer (TNBC) is a molecularly diverse grouping with poor prognosis for which chemotherapy remains the foundation of treatment. The molecular heterogeneity of the disease rationalizes its diverse biological behavior and differential response to treatment. Estimates of up to 20% of patients diagnosed have germline mutations in DNA-damage repair-pathway genes, namely BRCA1 and 2, and this can be used to select patients likely to respond to platinums and/or inhibitors of poly(ADP-ribose) polymerase (PARP). Similar strategies can be utilized in other subtypes of TNBC that have 'BRCA-like' tumor biology due to the presence of mutations in alternate DNA-damage repair genes. The diverse biological behavior of TNBC and its variable response to chemotherapy were largely decoded following genotyping studies that enabled the identification of distinct molecular subtypes, such that the biological and genetic heterogeneity of the disease could be understood. This subsequently enabled the identification of therapeutic 'vulnerabilities' for each subtype that encompass biological processes including proliferation, DNA repair, apoptosis, angiogenesis, immune modulation, and invasion and metastasis. To expedite the development of therapies for high-risk, early-stage breast cancer, we have adopted novel trial designs and re-defined endpoints as surrogates of clinical outcomes. The purpose of this review is to highlight the current standard and experimental treatment options for TNBC.