Gedatolisib in combination with palbociclib and endocrine therapy in women with hormone receptor-positive, HER2-negative advanced breast cancer: results from the dose expansion groups of an open-label, phase 1b study.

BACKGROUND: The PI3K-mTOR pathway is frequently dysregulated in breast cancer. Combining an inhibitor targeting all class I PI3K isoforms and mTOR complex 1 (mTORC1)-mTOR complex 2 (mTORC2) with endocrine therapy and a CDK4/6 inhibitor might provide more effective tumour control than standard-of-care therapy. To evaluate this hypothesis, gedatolisib, a pan-PI3K-mTOR inhibitor, was assessed in a phase 1b trial combined with palbociclib and endocrine therapy in patients with hormone receptor-positive, HER2-negative, advanced breast cancer. Results from the dose expansion portion of this trial are reported herein. METHODS: This multicentre, open-label, phase 1b study recruited female patients aged at least 18 years from 17 sites across the USA with hormone-receptor-positive, HER2-negative, advanced breast cancer and an Eastern Cooperative Oncology Group performance status of 0-1. Four patient groups were studied in the dose expansion portion of the study: treatment-naive in the advanced setting (first line; group A), progression on 1-2 lines of endocrine therapy but CDK4/6 inhibitor-naive (group B); and one or more previous lines (second-line and higher) of therapy, including a CDK4/6 inhibitor (groups C and D). Gedatolisib 180 mg was administered intravenously weekly in 28-day treatment cycles for groups A-C, and on days 1, 8, and 15 for group D. Letrozole (group A), fulvestrant (groups B-D), and palbociclib (all groups) were administered at standard doses and schedules. The primary endpoint was investigator-assessed objective response rate per RECIST version 1.1 in the evaluable analysis set. This trial is completed and registered with ClinicalTrials.gov, NCT02684032. FINDINGS: Between Dec 19, 2017, and June 19, 2019, 103 female participants were enrolled in the dose expansion groups A (n=31), B (n=13), C (n=32), and D (n=27). Median follow-up was 16·6 months (IQR 5·7-48·4) for group A, 11·0 months (7·6-16·9) for group B, 3·6 months (1·8-7·5) for group C, and 9·4 months (5·3-16·7) for group D for the primary endpoint. Gedatolisib, palbociclib, and endocrine therapy induced an objective response in 23 (85·2%; 90% CI 69·2-94·8) of 27 evaluable first-line participants (group A). In the second-line and higher setting, an objective response was observed in eight (61·5%; 90% CI 35·5-83·4) of 13 evaluable group B participants, seven (25·0%; 12·4-41·9) of 28 evaluable group C participants, and 15 (55·6%; 38·2-72·0) of 27 evaluable group D participants; this included participants with both wild-type and mutated PIK3CA tumours. The most common grade 3-4 treatment-related adverse events were neutropenia (65 [63%] of 103), stomatitis (28 [27%]), and rash (21 [20%]). Grade 3-4 hyperglycaemia was reported in six (6%) participants. 23 (22%) of 103 participants had a treatment-related serious adverse event, and there were no treatment-related deaths. Nine (9%) participants discontinued treatment because of a treatment-emergent adverse event. INTERPRETATION: Gedatolisib plus palbociclib and endocrine therapy showed a promising objective response rate compared with the published results for standard-of-care therapies and had an acceptable safety profile. FUNDING: Pfizer and Celcuity.

Breast cancer brain metastases localization and risk of hydrocephalus: a single institution experience.

PURPOSE: Brain metastases occur in up to one-third of patients with breast cancer. aromatase, a marker for estrogen activity that has been shown to promote such metastasis, heavily concentrates in certain midline structures of brain. We hypothesize that breast cancer metastasizes more often to brain areas with higher aromatase activity and that these patients have a higher risk of developing obstructive hydrocephalus. METHODS: In our retrospective review of 709 patients who underwent stereotactic radiosurgery (January 2014-May 2020), we identified 358 patients treated for metastatic breast or lung cancer. The MRI scan that first showed evidence of brain metastases was reviewed and number of metastases counted by location. Procedures used to treat obstructive hydrocephalus were recorded. Chi square test was used for statistical analysis. RESULTS: Of 358 patients, 99 patients with breast cancer had 618 brain metastases and 259 patients with lung cancer had 1487 brain metastases. Compared with expected distribution of brain metastases based on regional brain volumes and metastatic lung carcinoma as a control, patients with breast cancer more often had metastases to the cerebellum, diencephalon, medulla, and parietal lobe, and underwent significantly more neurosurgical interventions for treatment of obstructive hydrocephalus. CONCLUSION: Brain metastases in patients with breast cancer occurred more often along midline structures of the brain, which we believe may be associated with the increased estrogen activity in these structures. This finding is important for physicians who treat patients with metastatic breast cancer given the higher possibility of developing obstructive hydrocephalus.

Evaluating anthracycline + taxane versus taxane-based chemotherapy in older women with node-negative triple-negative breast cancer: a SEER-Medicare study.

PURPOSE: Adjuvant chemotherapy reduces recurrence in early-stage triple-negative breast cancer (TNBC). However, data are lacking evaluating anthracycline + taxane (ATAX) versus taxane-based (TAX) chemotherapy in older women with node-negative TNBC, as they are often excluded from trials. The purpose of this study was to evaluate the effect of adjuvant ATAX versus TAX on cancer-specific (CSS) and overall survival (OS) in older patients with node-negative TNBC. PATIENTS AND METHODS: Using the SEER-Medicare database, we selected patients aged ≥ 66 years diagnosed with Stage T1-4N0M0 TNBC between 2010 and 2015 (N = 3348). Kaplan-Meier survival curves and adjusted Cox proportional hazards models were used to estimate 3-year OS and CSS. Multivariant Cox regression analysis was used to identify independent factors associated with use of ATAX compared to TAX. RESULTS: Approximately half (N = 1679) of patients identified received chemotherapy and of these, 58.6% (N = 984) received TAX, 25.0% (N = 420) received ATAX, and 16.4% (N = 275) received another regimen. Three-year CSS and OS was improved with any adjuvant chemotherapy from 88.9 to 92.2% (p = 0.0018) for CSS and 77.2% to 88.6% for OS (p < 0.0001). In contrast, treatment with ATAX compared to TAX was associated with inferior 3-year CSS and OS. Three-year CSS was 93.7% with TAX compared to 89.8% (p = 0.048) for ATAX and OS was 91.0% for TAX and 86.4% for ATAX (p = 0.032). CONCLUSION: While adjuvant chemotherapy was associated with improved clinical outcomes, the administration of ATAX compared to TAX was associated with inferior 3-year OS and CSS in older women with node-negative TNBC. The use of adjuvant ATAX should be considered carefully in this patient population.

Neoadjuvant endocrine therapy expands stromal populations that predict poor prognosis in estrogen receptor-positive breast cancer.

The tumor microenvironment (TME) is an important modulator of response and resistance to endocrine therapy in estrogen receptor alpha (ER) positive breast cancer. Endocrine therapy is highly effective at reducing tumor burden and preventing recurrence in most estrogen receptor alpha (ER) positive breast cancers. Existing drugs work either directly by targeting tumor-cell ER or indirectly by inhibiting estrogen production in stromal cells with aromatase inhibitors (AI). However, many stromal cells also express ER and the direct impact of endocrine therapies on ER + stromal cells remain unclear. In this study, we investigated how neoadjuvant endocrine therapy (NET) directly effects stromal cells by measuring changes in stomal components of the TME that favor tumor progression. We previously defined two major subsets of tumor-associated stromal cells (TASCs): CD146 positive/CDCP1 negative (TASCCD146 ), CD146 negative/CDCP1 positive (TASCCDCP1 ), and generated a differentially expressed genes list associated with each type. Here, we applied the TASC gene list for classification and an algorithm that estimates immune cell abundance (TIMEx) to METABRIC transcriptomic data for ER + breast cancer patients coupled with multiplex imaging and analysis of paired tissue samples pre- and post- NET with the AI exemestane. TASCCDCP1 composition predicted for decreased patient survival in the METABRIC cohort. Exemestane treatment significantly increased expression of TASCCDCP1 and decreased expression of TASCCD146 . The posttreatment shift toward TASCCDCP1 composition correlated with increased macrophage infiltration and increased CD8+ T-cell, B cell, and general stromal components. The effectiveness of NET is currently based solely on the reduction of ER+ breast cancer cells. Here, we show NET displays clear TME effects that promote the expansion of the less favorable TASCCDCP1 population which are correlated with TME remodeling and reshaping immune infiltration supportive of tumor progression. Our findings highlight the need to further understand the role of endocrine therapy on TME remodeling, tumor progression, and patient outcomes.

Tumour-associated macrophages drive stromal cell-dependent collagen crosslinking and stiffening to promote breast cancer aggression.

Stromal stiffening accompanies malignancy, compromises treatment and promotes tumour aggression. Clarifying the molecular nature and the factors that regulate stromal stiffening in tumours should identify biomarkers to stratify patients for therapy and interventions to improve outcome. We profiled lysyl hydroxylase-mediated and lysyl oxidase-mediated collagen crosslinks and quantified the greatest abundance of total and complex collagen crosslinks in aggressive human breast cancer subtypes with the stiffest stroma. These tissues harbour the highest number of tumour-associated macrophages, whose therapeutic ablation in experimental models reduced metastasis, and decreased collagen crosslinks and stromal stiffening. Epithelial-targeted expression of the crosslinking enzyme, lysyl oxidase, had no impact on collagen crosslinking in PyMT mammary tumours, whereas stromal cell targeting did. Stromal cells in microdissected human tumours expressed the highest level of collagen crosslinking enzymes. Immunohistochemical analysis of biopsies from a cohort of patients with breast cancer revealed that stromal expression of lysyl hydroxylase 2, an enzyme that induces hydroxylysine aldehyde-derived collagen crosslinks and stromal stiffening, correlated significantly with disease specific mortality. The findings link tissue inflammation, stromal cell-mediated collagen crosslinking and stiffening to tumour aggression and identify lysyl hydroxylase 2 as a stromal biomarker.

Insulin receptor substrate-1 (IRS-1) mediates progesterone receptor-driven stemness and endocrine resistance in oestrogen receptor+ breast cancer.

BACKGROUND: Progesterone receptors (PR) are potent modifiers of endocrine responses. In aberrant signalling cancer contexts, phosphorylation events dramatically alter steroid hormone receptor action. METHODS: The transcriptomes of primary tumours and metastases in mice harbouring ER+ breast cancer patient-derived xenografts (PDXs) were analysed following single-cell RNAseq. In vitro assays were employed to delineate mechanisms of endocrine resistance and stemness. RESULTS: A 16-gene phospho-Ser294 PR (p-PR) signature predicted poor outcome in ER+ breast cancer. Relative to primary PDX tumours, metastatic lesions expressed abundant p-PR and exhibited an activated PR gene programme with elevated expression of PGR and IRS-1. Breast cancer models of activated PR lost the expression of IGF1R and acquired insulin hypersensitivity with tamoxifen insensitivity. Activated p-PR+ breast cancer cells formed increased tumourspheres with enlarged ALDH+ and CD24-/CD44 populations. E2 induced PR/IRS-1 interaction and exchange of IGF1Rß for IRS-1 in p-PR-containing transcriptional complexes. Inhibition of IRS-1 or IR and inducible IRS-1 knockdown reduced tumourspheres. Endocrine-resistant models of luminal B breast cancer induced p-PR in 3D cultures and required PR and IRS-1 for tumoursphere formation. CONCLUSIONS: Phospho-PR-B cooperates with IRS-1 to promote outgrowth of endocrine-resistant and stem-like breast cancer cells. Targeting phospho-PR/IRS-1 crosstalk may block the emergence of endocrine resistance.

Real-world evidence from a University Hospital system regarding the uptake of adjuvant pertuzumab and/or neratinib before and after their FDA approval.

PURPOSE: Adjuvant pertuzumab and neratinib are independently FDA-approved for treatment of early-stage HER2-positive breast cancer in combination with or following trastuzumab for one year, respectively. Both agents reduce the risk of recurrence; however, the absolute benefit is modest for many patients with added risk of adverse effects. The purpose of this study was to evaluate the clinical use of adjuvant pertuzumab and neratinib in patients with early-stage HER2-positive breast cancer. METHODS: Patients diagnosed with stage I-III HER2-positive breast cancer treated with trastuzumab at four University of Colorado Health hospitals between July 2016 and April 2019 were identified. Patient demographics, cancer stage, treatment, and administration of pertuzumab and/or neratinib were obtained. RESULTS: We identified a total of 350 patients who received adjuvant trastuzumab for stage I-III HER2-positive breast cancer; 253 (73.1%) had tumors that were ≥ T2 or node-positive disease. The rate of adjuvant pertuzumab use increased following FDA approval; pertuzumab was administered to the majority of patients with node-positive HER2-positive breast cancer. The use of adjuvant pertuzumab was associated with younger age, premenopausal status, and node-positive disease. Rates of administration of adjuvant neratinib were lower, with only 15.2% of patients receiving this therapy within 3 months of completing adjuvant trastuzumab. CONCLUSION: In our cohort of patients treated within a diverse healthcare network, the majority of patients with node-positive HER2-positive breast cancer received adjuvant pertuzumab following FDA approval. The use of adjuvant neratinib was less common, potentially as a result of adverse effects, prolongation of therapy, previous administration of adjuvant pertuzumab, and modest benefit.

New Persistent Opioid and Benzodiazepine Use After Curative-Intent Treatment in Patients With Breast Cancer.

BACKGROUND: Opioid and benzodiazepine use and abuse is a national healthcare crisis to which patients with cancer are particularly vulnerable. Long-term use and risk factors for opioid and benzodiazepine use in patients with breast cancer is poorly characterized. METHODS: We conducted a retrospective population-based study of patients with breast cancer diagnosed between 2008 and 2015 undergoing curative-intent treatment identified through the SEER-Medicare linked database. Primary outcomes were new persistent opioid use and new persistent benzodiazepine use. Factors associated with new opioid and benzodiazepine use were investigated by univariate and multivariable logistic regression. RESULTS: Among opioid-naïve patients, new opioid use was observed in 22,418 (67.4%). Of this group, 611 (2.7%) developed persistent opioid use at 3 months and 157 (0.7%) at 6 months after treatment. Risk factors for persistent use at 3 and 6 months included stage III disease (odds ratio [OR], 2.16; 95% CI, 1.49-3.12, and OR, 3.48; 95% CI, 1.58-7.67), surgery plus chemotherapy (OR, 1.44; 95% CI, 1.10-1.88, and OR, 2.28; 95% CI, 1.40-3.71), surgery plus chemoradiation therapy (OR, 1.47; 95% CI, 1.10-1.96, and OR, 2.34; 95% CI, 1.38-3.96), and initial tramadol use (OR, 2.66; 95% CI, 2.05-3.46, and OR, 3.12; 95% CI, 1.93-5.04). Among benzodiazepine-naïve patients, new benzodiazepine use was observed in 955 (10.3%), and 111 (11.6%) developed new persistent use at 3 months. Tamoxifen use was statistically significantly associated with new persistent benzodiazepine use at 3 months. CONCLUSIONS: A large percentage of patients receiving curative-intent treatment of breast cancer were prescribed new opioids; however, only a small number developed new persistent opioid use. In contrast, a smaller proportion of patients received a new benzodiazepine prescription; however, new persistent use after completion of treatment was more likely and particularly related to concurrent treatment with tamoxifen.

Recovery and analysis of transcriptome subsets from pooled single-cell RNA-seq libraries.

Single-cell RNA sequencing (scRNA-seq) methods generate sparse gene expression profiles for thousands of single cells in a single experiment. The information in these profiles is sufficient to classify cell types by distinct expression patterns but the high complexity of scRNA-seq libraries often prevents full characterization of transcriptomes from individual cells. To extract more focused gene expression information from scRNA-seq libraries, we developed a strategy to physically recover the DNA molecules comprising transcriptome subsets, enabling deeper interrogation of the isolated molecules by another round of DNA sequencing. We applied the method in cell-centric and gene-centric modes to isolate cDNA fragments from scRNA-seq libraries. First, we resampled the transcriptomes of rare, single megakaryocytes from a complex mixture of lymphocytes and analyzed them in a second round of DNA sequencing, yielding up to 20-fold greater sequencing depth per cell and increasing the number of genes detected per cell from a median of 1313 to 2002. We similarly isolated mRNAs from targeted T cells to improve the reconstruction of their VDJ-rearranged immune receptor mRNAs. Second, we isolated CD3D mRNA fragments expressed across cells in a scRNA-seq library prepared from a clonal T cell line, increasing the number of cells with detected CD3D expression from 59.7% to 100%. Transcriptome resampling is a general approach to recover targeted gene expression information from single-cell RNA sequencing libraries that enhances the utility of these costly experiments, and may be applicable to the targeted recovery of molecules from other single-cell assays.

New generation breast cancer cell lines developed from patient-derived xenografts.

BACKGROUND: Breast cancer is a highly heterogeneous disease characterized by multiple histologic and molecular subtypes. While a myriad of breast cancer cell lines have been developed over the past 60 years, estrogen receptor alpha (ER)+ disease and some mutations associated with this subtype remain underrepresented. Here we describe six breast cancer cell lines derived from patient-derived xenografts (PDX) and their general characteristics. METHODS: Established breast cancer PDX were processed into cell suspensions and placed into standard 2D cell culture; six emerged into long-term passageable cell lines. Cell lines were assessed for protein expression of common luminal, basal, and mesenchymal markers, growth assessed in response to estrogens and endocrine therapies, and RNA-seq and oncogenomics testing performed to compare relative transcript levels and identify putative oncogenic drivers. RESULTS: Three cell lines express ER and two are also progesterone receptor (PR) positive; PAM50 subtyping identified one line as luminal A. One of the ER+PR+ lines harbors a D538G mutation in the gene for ER (ESR1), providing a natural model that contains this endocrine-resistant genotype. The third ER+PR-/low cell line has mucinous features, a rare histologic type of breast cancer. The three other lines are ER- and represent two basal-like and a mixed ductal/lobular breast cancer. The cell lines show varied responses to tamoxifen and fulvestrant, and three were demonstrated to regrow tumors in vivo. RNA sequencing confirms all cell lines are human and epithelial. Targeted oncogenomics testing confirmed the noted ESR1 mutation in addition to other mutations (i.e., PIK3CA, BRCA2, CCND1, NF1, TP53, MYC) and amplifications (i.e., FGFR1, FGFR3) frequently found in breast cancers. CONCLUSIONS: These new generation breast cancer cell lines add to the existing repository of breast cancer models, increase the number of ER+ lines, and provide a resource that can be genetically modified for studying several important clinical breast cancer features.

Analysis of circulating breast cancer cell heterogeneity and interactions with peripheral blood mononuclear cells.

For solid tumors, extravasation of cancer cells and their survival in circulation represents a critical stage of the metastatic process that lacks complete understanding. Gaining insight into interactions between circulating tumor cells (CTCs) and other peripheral blood mononuclear cells (PBMCs) may provide valuable prognostic information. The purpose of this study was to use single-cell RNA-sequencing (scRNA-seq) of liquid biopsies from breast cancer patients to begin defining intravascular interactions. We captured CTCs from the peripheral blood of breast cancer patients using size-exclusion membranes followed by scRNA-seq of enriched CTCs and carry-over PBMCs. Transcriptome analysis identified two populations of CTCs: one enriched for transcripts indicative of estrogen responsiveness and increased proliferation and another enriched for transcripts characteristic of reduced proliferation and epithelial-mesenchymal transition (EMT). We applied interactome and pathway analysis to determine interactions between CTCs and other captured cells. Our analysis predicted for enhanced immune evasion in the CTC population with EMT characteristics. In addition, PD-1/PD-L1 pathway activation and T cell exhaustion were predicted in T cells isolated from breast cancer patients compared with normal T cells. We conclude that scRNA-seq of breast cancer CTCs generally stratifies them into two types based on their proliferative and epithelial state and differential potential to interact with PBMCs. Better understanding of CTC subtypes and their intravascular interactions may help design treatments directed against CTCs with high metastatic and immune-evasive competence.

A phase II clinical trial of the Aurora and angiogenic kinase inhibitor ENMD-2076 for previously treated, advanced, or metastatic triple-negative breast cancer.

BACKGROUND: Triple-negative breast cancer (TNBC) remains an aggressive breast cancer subtype with limited treatment options. ENMD-2076 is a small-molecule inhibitor of Aurora and angiogenic kinases with proapoptotic and antiproliferative activity in preclinical models of TNBC. METHODS: This dual-institution, single-arm, two-stage, phase II clinical trial enrolled patients with locally advanced or metastatic TNBC previously treated with one to three prior lines of chemotherapy in the advanced setting. Patients were treated with ENMD-2076 250 mg orally once daily with continuous dosing in 4-week cycles until disease progression or unacceptable toxicity occurred. The primary endpoint was 6-month clinical benefit rate (CBR), and secondary endpoints included progression-free survival, pharmacokinetic profile, safety, and biologic correlates in archival and fresh serial tumor biopsies in a subset of patients. RESULTS: Forty-one patients were enrolled. The 6-month CBR was 16.7% (95% CI, 6-32.8%) and included two partial responses. The 4-month CBR was 27.8% (95% CI, 14-45.2%), and the average duration of benefit was 6.5 cycles. Common adverse events included hypertension, fatigue, diarrhea, and nausea. Treatment with ENMD-2076 resulted in a decrease in cellular proliferation and microvessel density and an increase in p53 and p73 expression, consistent with preclinical observations. CONCLUSIONS: Single-agent ENMD-2076 treatment resulted in partial response or clinical benefit lasting more than 6 months in 16.7% of patients with pretreated, advanced, or metastatic TNBC. These results support the development of predictive biomarkers using archival and fresh tumor tissue, as well as consideration of mechanism-based combination strategies. TRIAL REGISTRATION: ClinicalTrials.gov, NCT01639248 . Registered on July 12, 2012.

Patient-derived xenograft (PDX) models in basic and translational breast cancer research.

Patient-derived xenograft (PDX) models of a growing spectrum of cancers are rapidly supplanting long-established traditional cell lines as preferred models for conducting basic and translational preclinical research. In breast cancer, to complement the now curated collection of approximately 45 long-established human breast cancer cell lines, a newly formed consortium of academic laboratories, currently from Europe, Australia, and North America, herein summarizes data on over 500 stably transplantable PDX models representing all three clinical subtypes of breast cancer (ER+, HER2+, and "Triple-negative" (TNBC)). Many of these models are well-characterized with respect to genomic, transcriptomic, and proteomic features, metastatic behavior, and treatment response to a variety of standard-of-care and experimental therapeutics. These stably transplantable PDX lines are generally available for dissemination to laboratories conducting translational research, and contact information for each collection is provided. This review summarizes current experiences related to PDX generation across participating groups, efforts to develop data standards for annotation and dissemination of patient clinical information that does not compromise patient privacy, efforts to develop complementary data standards for annotation of PDX characteristics and biology, and progress toward "credentialing" of PDX models as surrogates to represent individual patients for use in preclinical and co-clinical translational research. In addition, this review highlights important unresolved questions, as well as current limitations, that have hampered more efficient generation of PDX lines and more rapid adoption of PDX use in translational breast cancer research.

The 21-Gene Recurrence Score Assay for Node-Positive, Early-Stage Breast Cancer and Impact of RxPONDER Trial on Chemotherapy Decision-Making: Have Clinicians Already Decided?

Background: The 21-gene recurrence score (RS) assay is retrospectively validated for assessing prognosis and benefit from chemotherapy in hormone receptor-positive, early-stage breast cancer (EBC) with low RS. We hypothesized that oncologists have already incorporated the RS assay for decision-making in higher-risk, node-positive disease, despite the lack of prospective data and contrary to NCCN Guideline recommendations. This study provides the first analysis of trends and differences in RS use and therapeutic implications in a population-based data set of patients with node-positive EBC. It also assesses the impact of the RxPONDER trial on clinicians' chemotherapy recommendations. Methods: Node-positive EBC cases diagnosed during 2010 through 2012 and included in the National Cancer Data Base were used. Multivariate logistic regression was used to estimate test use and impact on chemotherapy recommendations. Results: The RS assay was ordered for 16.5% of the 80,405 identified patients. Of all variables, the RS assay had the strongest association with chemotherapy recommendation, with adjusted odds ratios (AORs) of 19 for scores >30. Odds of chemotherapy recommendation were significantly lower for the group who received the test (AOR, 0.21; 95% CI, 0.20-0.22). When divided based on the cutoff point of 25 adopted by the RxPONDER trial, those with an RS of 18 to 25 had significantly lower odds of chemotherapy recommendation compared with those with an RS of 26 to 30 (AOR, 0.32; 95% CI, 0.26-0.40). Test use was lower for blacks, community centers, uninsured/governmentally insured patients, higher tumor grade, larger tumor size, and more nodes involved. Chemotherapy recommendation was higher for patients of younger age, with private insurance, and with higher tumor grade, size, and number of nodes involved. Black patients had significantly higher RS (AOR, 1.37; 95% CI, 1.25-1.79). Conclusions: The RS assay influences clinicians' chemotherapy recommendation in node-positive EBC. Clinicians are using the inclusion criteria of the RxPONDER trial before its final release. Black patients have higher RS, likely representing worse biology. Significant differences exist in test use and clinical implications based on race, insurance, and facility.

Improvements to the HITS-CLIP protocol eliminate widespread mispriming artifacts.

BACKGROUND: High-throughput sequencing of RNA isolated by crosslinking immunoprecipitation (HITS-CLIP) allows for high resolution, genome-wide mapping of RNA-binding proteins. This methodology is frequently used to validate predicted targets of microRNA binding, as well as direct targets of other RNA-binding proteins. Hence, the accuracy and sensitivity of binding site identification is critical. RESULTS: We found that substantial mispriming during reverse transcription results in the overrepresentation of sequences complementary to the primer used for reverse transcription. Up to 45 % of peaks in publicly available HITS-CLIP libraries are attributable to this mispriming artifact, and the majority of libraries have detectable levels of mispriming. We also found that standard techniques for validating microRNA-target interactions fail to differentiate between artifactual peaks and physiologically relevant peaks. CONCLUSIONS: Here, we present a modification to the HITS-CLIP protocol that effectively eliminates this artifact and improves the sensitivity and complexity of resulting libraries.

Breast Cancer Following Radiation for Hodgkin Lymphoma: Clinical Scenarios and Risk-Reducing Strategies.

Since most patients with Hodgkin lymphoma survive their disease, long-term issues such as development of second primary malignancies arise, especially in patients treated with multimodal therapy including radiation therapy plus chemotherapy. The risk of breast cancer is significantly elevated in women exposed to high-dose ionizing radiation to the chest before age 40. The case of a 48-year-old patient with a lump in her right breast is presented as a clinical scenario in this article. We review available strategies for screening and risk reduction through chemoprevention or risk-reducing surgery, as well as challenges for management of breast cancer in patients with prior exposure to radiation for Hodgkin lymphoma. The Children's Oncology Group clinical practice guidelines for long-term follow-up care of pediatric cancer survivors provide recommendations that have been endorsed by American and European oncologists.

Genome-wide analysis of miRNA-mRNA interactions in marrow stromal cells.

Regulation of hematopoietic stem cell proliferation, lineage commitment, and differentiation in adult vertebrates requires extrinsic signals provided by cells in the marrow microenvironment (ME) located within the bone marrow. Both secreted and cell-surface bound factors critical to this regulation have been identified, yet control of their expression by cells within the ME has not been addressed. Herein we hypothesize that microRNAs (miRNAs) contribute to their controlled expression. MiRNAs are small noncoding RNAs that bind to target mRNAs and downregulate gene expression by either initiating mRNA degradation or preventing peptide translation. Testing the role of miRNAs in downregulating gene expression has been difficult since conventional techniques used to define miRNA-mRNA interactions are indirect and have high false-positive and negative rates. In this report, a genome-wide biochemical technique (high-throughput sequencing of RNA isolated by cross-linking immunoprecipitation or HITS-CLIP) was used to generate unbiased genome-wide maps of miRNA-mRNA interactions in two critical cellular components of the marrow ME: marrow stromal cells and bone marrow endothelial cells. Analysis of these datasets identified miRNAs as direct regulators of JAG1, WNT5A, MMP2, and VEGFA; four factors that are important to ME function. Our results show the feasibility and utility of unbiased genome-wide biochemical techniques in dissecting the role of miRNAs in regulation of complex tissues such as the marrow ME.

HITS-CLIP reveals key regulators of nuclear receptor signaling in breast cancer.

miRNAs regulate the expression of genes in both normal physiology and disease. While miRNAs have been demonstrated to play a pivotal role in aspects of cancer biology, these reports have generally focused on the regulation of single genes. Such single-gene approaches have significant limitations, relying on miRNA expression levels and heuristic predictions of mRNA-binding sites. This results in only circumstantial evidence of miRNA-target interaction and typically leads to large numbers of false positive predictions. Here, we used a genome-wide approach (high-throughput sequencing of RNA isolated by crosslinking immunoprecipitation, HITS-CLIP) to define direct miRNA-mRNA interactions in three breast cancer subtypes (estrogen receptor positive, Her2 amplified, and triple negative). Focusing on steroid receptor signaling, we identified two novel regulators of the ER pathway (miR-9-5p and miR-193a/b-3p), which together target multiple genes involved in ER signaling. Moreover, this approach enabled the definition of miR-9-5p as a global regulator of steroid receptor signaling in breast cancer. We show that miRNA targets and networks defined by HITS-CLIP under physiologic conditions are predictive of patient outcomes and provide global insight into miRNA regulation in breast cancer.

Targeting aberrant fatty acid synthesis and storage in endocrine resistant breast cancer cells.

Background: Lipid metabolic reprogramming is an emerging characteristic of endocrine therapy (ET) resistance in estrogen receptor-positive (ER+) breast cancer. We explored changes in lipid metabolism in ER+ breast cancer cell lines following acquired resistance to common endocrine treatments and tested efficacy of an inhibitor in current clinical trials. Methods: We derived ER+ breast cancer cell lines resistant to Tamoxifen (TamR), Fulvestrant (FulvR), and long-term estrogen withdrawal (EWD). Parental and ET resistant cells were subjected to global gene expression and unbiased lipidomic profiling. Lipid storage changes were assessed via neutral lipid staining with Oil Red O (ORO). The impact of the fatty acid synthase (FASN) inhibitor TVB-2640 on the growth and lipid storage of these cell lines was evaluated. Additionally, 13 C 2 -acetate tracing was used to examine FASN activity in parental and ET resistant cells in the absence or presence of TVB-2640. Results: Compared to parental cells, lipid metabolism and processing pathways were notably enriched in ET resistant cells, which exhibited distinct lipidomes characterized by increased triglyceride and polyunsaturated FA (PUFA) species. ET-resistant cells displayed enhanced cytoplasmic lipid droplets. Increased FASN protein levels were observed in ET-resistant cells, and TVB-2640 effectively inhibited FASN activity. FASN inhibition reduced cell growth in some but not all cell lines and ET resistance types and did not correlate to lipid storage reduction. 13 C 2 -acetate tracing confirmed reduced palmitate synthesis and enhanced PUFA synthesis in ET-resistant cells, especially when combined with FulvR. Conclusion: ET resistant breast cancer cells exhibit a shift towards enhanced triglyceride storage and complex lipids enriched with PUFA acyl chains. While targeting FASN alongside ET may not fully overcome ET resistance in our models, focusing on the unique lipid metabolic dependencies, such as PUFA pathways, may present a promising alternative strategy for treating ET resistant breast cancer.

Phase Ia/b Study of Giredestrant ± Palbociclib and ± Luteinizing Hormone-Releasing Hormone Agonists in Estrogen Receptor-Positive, HER2-Negative, Locally Advanced/Metastatic Breast Cancer.

PURPOSE: Giredestrant is an investigational next-generation, oral, selective estrogen receptor antagonist and degrader for the treatment of estrogen receptor-positive (ER+) breast cancer. We present the primary analysis results of the phase Ia/b GO39932 study (NCT03332797). PATIENTS AND METHODS: Patients with ER+, HER2-negative locally advanced/metastatic breast cancer previously treated with endocrine therapy received single-agent giredestrant (10, 30, 90, or 250 mg), or giredestrant (100 mg) ± palbociclib 125 mg ± luteinizing hormone-releasing hormone (LHRH) agonist. Detailed cardiovascular assessment was conducted with giredestrant 100 mg. Endpoints included safety (primary), pharmacokinetics, pharmacodynamics, and efficacy. RESULTS: As of January 28, 2021, with 175 patients enrolled, no dose-limiting toxicity was observed, and the MTD was not reached. Adverse events (AE) related to giredestrant occurred in 64.9% and 59.4% of patients in the single-agent ± LHRH agonist and giredestrant + palbociclib ± LHRH agonist cohorts, respectively (giredestrant-only-related grade 3/4 AEs were reported in 4.5% of patients across the single-agent cohorts and 3.1% of those with giredestrant + palbociclib). Dose-dependent asymptomatic bradycardia was observed, but no clinically significant changes in cardiac-related outcomes: heart rate, blood pressure, or exercise duration. Clinical benefit was observed in all cohorts (48.6% of patients in the single-agent cohort and 81.3% in the giredestrant + palbociclib ± LHRH agonist cohort), with no clear dose relationship, including in patients with ESR1-mutated tumors. CONCLUSIONS: Giredestrant was well tolerated and clinically active in patients who progressed on prior endocrine therapy. Results warrant further evaluation of giredestrant in randomized trials in early- and late-stage ER+ breast cancer.