An Unlikely Source of Iodine Uptake: A Bronchogenic Cyst Masquerading as Metastatic Thyroid Cancer

Radioactive iodine therapy and posttreatment scanning are essential components of differentiated thyroid carcinoma treatment and detection of metastatic disease. False-positive results can be seen on an I-131 scan and are important for clinicians to be aware of. Here, we present a case of a 33-year-old female with follicular thyroid carcinoma who was noted to have an area of moderate uptake in the chest on a whole-body scan following remnant ablation with 30 mCi of I-131 (1.11GBq) concerning for a metastatic hilar lymph node. This was determined to be a mediastinal bronchogenic cyst on surgical pathology. It has been previously proposed that the expression of sodium iodide symporters in some bronchogenic cysts could be the mechanism by which iodine uptake is seen within them. We were able to demonstrate positive immunohistochemical staining for both sodium iodide symporter and the associated paired box gene 8 transcription factor in the cyst sample, which supports the proposed theory.

Defining Ultra-Massive Transfusion through a Systematic Review

Background

Despite the widespread use of ultra-massive transfusion (UMT) as an intervention for trauma patients in hemorrhagic shock, no standard definition exists. We performed a systematic review to determine a consensus definition for UMT.

Methods

A search was performed from 1979-2022. The authors screened studies defining UMT and associated outcomes as defined by our prespecified PICO questions. The PRISMA guidelines were used.

Results

1662 articles met criteria for eligibility assessment, 17 for full-text review and eight for data extraction. Only two studies demonstrated a consensus definition of UMT, which used ≥20 units of red blood cell product within 24hrs. Parameters associated with increased mortality included lower blood pressure, lower pulse and lower Glasgow Coma Score at the time of presentation and a higher injury severity score and undergoing a resuscitative thoracotomy.

Conclusions

The absence of a consensus definition for UMT raises challenges from clinical, research and ethical perspectives. Based on our findings, the authors advocate for the feasibility of standardizing the definition of UMT as ≥20 units of red blood cell product within 24hrs.

Rare Primary Fallopian Tube Grade 2 Neuroendocrine Tumor: A Case Report With Review of Literature

Neuroendocrine neoplasms commonly arise from the gastrointestinal tract and lungs. Less commonly, they may occur in the gynecologic tract, typically within the ovary of a mature cystic teratoma. Primary neuroendocrine neoplasms of the fallopian tube are exceptionally rare and only a total of 11 cases have been reported in the literature. We describe the first case to our knowledge of a primary grade 2 neuroendocrine tumor of the fallopian tube in a 47-yr-old female. In this report, we describe the case's unique presentation, review the published literature on primary neuroendocrine neoplasms of the fallopian tube, discuss the treatment options, and speculate on their origin and histogenesis.

Robust biomarker discovery through multiplatform multiplex image analysis of breast cancer clinical cohorts

Spatial profiling of tissues promises to elucidate tumor-microenvironment interactions and enable development of spatial biomarkers to predict patient response to immunotherapy and other therapeutics. However, spatial biomarker discovery is often carried out on a single patient cohort or imaging technology, limiting statistical power and increasing the likelihood of technical artifacts. In order to analyze multiple patient cohorts profiled on different platforms, we developed methods for comparative data analysis from three disparate multiplex imaging technologies: 1) cyclic immunofluorescence data we generated from 102 breast cancer patients with clinical follow-up, in addition to publicly available 2) imaging mass cytometry and 3) multiplex ion-beam imaging data. We demonstrate similar single-cell phenotyping results across breast cancer patient cohorts imaged with these three technologies and identify cellular abundance and proximity-based biomarkers with prognostic value across platforms. In multiple platforms, we identified lymphocyte infiltration as independently associated with longer survival in triple negative and high-proliferation breast tumors. Then, a comparison of nine spatial analysis methods revealed robust spatial biomarkers. In estrogen receptor-positive disease, quiescent stromal cells close to tumor were more abundant in good prognosis tumors while tumor neighborhoods of mixed fibroblast phenotypes were enriched in poor prognosis tumors. In triple-negative breast cancer (TNBC), macrophage proximity to tumor and B cell proximity to T cells were greater in good prognosis tumors, while tumor neighborhoods of vimentin-positive fibroblasts were enriched in poor prognosis tumors. We also tested previously published spatial biomarkers in our ensemble cohort, reproducing the positive prognostic value of isolated lymphocytes and lymphocyte occupancy and failing to reproduce the prognostic value of tumor-immune mixing score in TNBC. In conclusion, we demonstrate assembly of larger clinical cohorts from diverse platforms to aid in prognostic spatial biomarker identification and validation.

Abstract PD2-06: Implications of Heterogeneity in Breast Tumor Cell MHC-I Expression on Immunity and Therapeutic Resistance

Background Immune checkpoint inhibitors (ICIs) targeting the PD-1/L1 axis are approved in early-stage treatment for triple-negative breast cancer (TNBC), but only a fraction of patients benefit. Tumor expressed antigens bound to major histocompatibility complex-I (MHC-I) are required for CD8-mediated tumoricidal activity, and thus, response to anti-PD-1/L1 targeted ICI. However, many breast tumors downregulate, or heterogeneously express, MHC-I, making them less susceptible to ICIs. Tumor cells downregulating MHC-I may be effectively targeted by natural killer (NK) cells due to ‘missing self’ signals. However, this heterogeneity in MHC-I expression is poorly modeled in most preclinical studies, limiting our understanding of how to overcome ICI resistance in the context of heterogeneous MHC-I expression, as is often observed clinically. Objective We aimed to 1) quantitatively delineate how intratumoral heterogeneity in MHC class I expression affects immune responses and immunotherapy outcomes in mouse models and 2) determine whether targeting inhibitory signals on NK cells can overcome ICI resistance in MHC-I heterogenous TNBC. Methods We performed quantitative immunofluorescence for MHC-I, CD8, CD56, and pan-cytokeratin on breast cancer tumors from diverse subtypes (n=314) to obtain single-cell-resolution MHC-I expression and spatial information of tumor and immune cells. Fluorescence intensity and spatial analysis were processed to output individual tumor/stromal cell MHC-I expression and the composition of the local tumor microenvironment. To determine the functional effect of MHC-I heterogeneity in vivo, we generated a CRISPR-guided B2m knockout (B2m-null) in a murine orthotopic model (EMT6). We then combined MHC-I-proficient and MHC-I-deficient isogenic lines at various ratios to model how populations of MHC-I loss affected the immune microenvironment. We also assessed a second, intrinsically heterogenous (MHC-I expression) TNBC model E0771. To evaluate changes in the microenvironment, we used flow cytometry and an immune NanoString panel to evaluate gene expression patterns in tumor cells and infiltrating immune cells. Results TNBC patients had the highest MHC-I expression level across tumor cells, but also the highest variability and probability of demonstrating bimodal MHC-I expression (consisting of high and low/absent cells within a single tumor). ER+ tumors were unimodally low. Using spatial analysis, we identified that heterogenous MHC-I tumors had significantly higher levels of infiltrating NK cells(Paired T-Test: p=0.03). In murine models, even 10% or less of MHC-I-null (B2m-null) EMT6 cells in the tumor injection resulted in acquisition of ICI resistance. Interestingly, heterogeneity in expression of MHC-I resulted in a substantial infiltration by NKG2A+ NK cells compared to MHC-I high or -low tumors (Student T-Test: p=.002). Activation of these infiltrating NK cells via anti-NKG2A and anti-PD-L1 combination treatment restored complete responses in heterogeneous EMT6 tumors, and significantly extended survival in both E0771 (Mantel-Cox: p< 0.0001) and EMT6 models (Mantel-Cox: < 0.0001). Additionally, anti-NKG2A and anti-PDL1 combination treatment improved complete response in the heterogenous MHC-I EMT6 model to 30% and in the parental EMT-6 tumors to 70%. Conclusion Combined therapy with anti-NKG2A (targeting NK cells) and anti-PD-L1 (targeting CD8+ T cells) can restore immunotherapy responses and overcome resistance due to lack of MHC-I expression in tumor cell subpopulations.

Citation Format: Brandie C. Taylor, Xiaopeng Sun, Justin Balko, Paula Gonzalez-Ericsson, Melinda Sanders. Implications of Heterogeneity in Breast Tumor Cell MHC-I Expression on Immunity and Therapeutic Resistance [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr PD2-06.

Abstract PD2-02: Longitudinal local and peripheral immunologic changes associated with checkpoint inhibition response in murine models of breast cancer

Immune checkpoint inhibitors (ICI) have significantly enhanced patient survival in some cancer types but yield limited success in breast cancer. ICIs activate anti-tumor immunity by overriding the inhibition of tumor infiltrating lymphocytes (TILs). Clinical trials in triple negative breast cancer (TNBC) patients, who are more likely to harbor TILs within tumor stroma, have demonstrated increased progression-free survival (IMpassion130) and pathologic complete response (KEYNOTE-522) to ICI. Consequently, combinations of ICI and chemotherapy have been FDA-approved for metastatic TNBC. However, the therapeutic benefit of ICIs is highly heterogeneous among breast cancer patients; as such, we sought to model ICI response in vivo to evaluate therapeutic resistance and response heterogeneity, as well as ascertain predictive biomarkers for favorable outcomes to ICI in breast cancer. We used an immunocompetent EMT6 orthotopic mammary tumor model to investigate the efficacy of ICI (anti-PD-L1). Analysis of the primary tumor immune landscape was performed by flow cytometry and single-cell RNA sequencing. Matched longitudinal samples of the tumor microenvironment (collected by fine-needle aspiration) and peripheral blood (PBMC) from mice were profiled by bulk RNA and T-cell receptor (TCR) sequencing to identify systemic genomic alterations and T-cell expansion, respectively. Single-agent ICI robustly suppressed primary tumor growth (p =0.0046) and extended survival (p< 0.0001) beyond the control group in the EMT6 model. The addition of chemotherapy (paclitaxel and/or doxorubicin) demonstrated moderate therapeutic efficacy but failed to enhance ICI benefit. Phenotypic profiling of the tumor microenvironment (TME) revealed increased T cells, dendritic cells, and NK cells in anti-PD-L1 only and chemotherapy combination groups. Despite using a genetically identical tumor model and murine host, we found that PD-L1 blockade induced heterogeneous responses, similar to clinical outcomes in breast cancer patients, ranging from complete response to intrinsic resistance. Analysis of the primary tumor microenvironment showed upregulated signatures of cytotoxic T cell response and activation, specifically inflammatory interferon signaling (both prior to and post ICI administration) that corresponded to favorable response to anti-PD-L1 in individual mice. Longitudinal analysis of the peripheral blood identified modest changes among mice at baseline that progressively deviated by response type (non responders-vs-responder mice). Moreover, mice harbored enriched myeloid signatures and clonal T cell expansion during therapy corresponding to ICI resistance and response, respectively. Further investigations of matched peripheral blood and the primary tumor microenvironment signatures may identify systemic biomarkers and tumor antigen-specific T cell clones to accurately predict ICI response in patients and uncover mechanisms for sensitizing tumors refractory to ICI. In conclusion, we identify a heterogeneously ICI-responsive in vivo model that emulates TNBC patient response to combinatorial ICI approaches. We describe host-specific signatures, specifically myeloid cell responses, that correlate with differential responses to immunotherapy, which may serve as a basis for tracking immunotherapy response in peripheral blood from breast cancer patients.

Citation Format: Ann Hanna, Xiaopeng Sun, Quanhu Sheng, Melinda Sanders, Justin Balko. Longitudinal local and peripheral immunologic changes associated with checkpoint inhibition response in murine models of breast cancer [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr PD2-02.

Abstract 6149: Prognostic tumor microenvironment subtypes in triple-negative breast cancer

Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer in which the tumor microenvironment (TME) is prognostic, with increased tumor-infiltrating lymphocytes predicting a good prognosis. Positive clinical trials of immune checkpoint inhibitors in TNBC further highlight the TME’s importance, but its single-cell composition and relationship to patient survival has not been well described. Therefore, we generated highly-multiplex cyclic immunofluorescence (CyCIF) data from 59 TNBC in tissue microarrays. Our CyCIF dataset served as a discovery cohort; the data included 35 protein markers and clinical outcomes for 18 patients. For a validation cohort, we analyzed 32 markers imaged with multiplex ion beam imaging (MIBI) in 38 TNBC patients (Keren et. al., Cell 2018). In the CyCIF cohort, we used markers’ single-cell mean intensity to generate a Umap manifold, which we clustered with the unsupervised Leiden algorithm. We annotated the resulting 28 cell types as epithelial, immune or stromal. In the MIBI cohort, we similarly clustered and annotated 21 cell types as epithelial, immune or stromal. Next, we clustered the patients based on the fraction of epithelial, immune or stromal cells in the tissue. In the CyCIF cohort, patients fell into three subtypes: epithelial-rich, stroma-rich and immune-rich. The patients in the epithelial-rich group had significantly shorter survival than the other two subtypes (log-rank p-value = 0.0008) and had shorter recurrence-free survival (log-rank p-value = 0.048). In the MIBI cohort, patients fell into the same three subtypes. As in the CyCIF cohort, the epithelial-rich patients had shorter survival than the other subtypes (log-rank p-value = 0.021), although there was no difference in recurrence-free survival (log-rank p-value = 0.47). Finally, we identified protein biomarkers with significantly different expression levels between the subtypes in one or both cohorts. The poor-prognosis, epithelial-rich subtype had higher CD31 expression in both cohorts, and in the CyCIF cohort, Glut1 was elevated, indicating a hypoxic, angiogenic TME. The immune infiltrate was primarily CD68+ macrophages and the stroma was activated, with higher levels of Ki67 in both cohorts. In contrast, the stroma-rich, good prognosis subtype had low immune infiltration, including fewer macrophages, low CD31 expression and a quiescent, non-proliferating stroma. Lastly, the good-prognosis, immune-rich subtype had high T and B cells levels, as well as markers of immune regulation, memory cells, and antigen presentation cells. In conclusion, we generated and analyzed a new multiplex CyCIF dataset with clinical annotation and confirmed our analytical findings in a second multiplex imaging dataset. We delineated three TME subtypes in TNBC with different outcomes, cell types and biomarker expression, potentially leading to better patient stratification and informing new drug targets.

Citation Format: Jennifer R. Eng, Elmar Bucher, Zhi Hu, Melinda Sanders, Bapsi Chakravarthy, Summer Gibbs, Koei Chin, Jennifer Pietenpol, Joe W. Gray. Prognostic tumor microenvironment subtypes in triple-negative breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 6149.

Pre-clinical evaluation of a third generation absorbable antibacterial envelope

Funding Acknowledgements

Type of funding sources: Private company. Main funding source(s): Medtronic

Background

An absorbable antibacterial envelope (TYRX), which stabilizes cardiac implantable electronic devices (CIEDs) was shown to significantly reduce infections in a large randomized controlled trial (WRAP-IT). A 3rd generation envelope (T3) is being developed to improve the implanter experience and enable smoother device insertion with a redesigned, multifilament mesh, an enhanced form factor, and identical polymer coating and antibiotic concentrations as the currently available 2nd generation envelope (T2).

Purpose

To compare drug elution profiles of T3 vs T2 and evaluate the efficacy of T3 against bacteria commonly known to be associated with CIED infections.

Methods

The T3 drug elution profile was assessed in vitro by evaluating the amount of each drug, minocycline and rifampin, released at a given timepoint using an accelerated dissolution method. For comparative analysis with T2, elution curve equivalency was based on similarity factor values (f2) of ≥50 per FDA guidance. An in vivo elution study was also conducted (per the Principles of Laboratory Animal Care [NIH Publication no. 85-23 revised 1985]) to ensure drug concentrations met the minimal inhibitory concentration (MIC) through 7 days. Substantial equivalence was defined as rifampin and minocycline concentrations above MIC at 2hr post-implant and sustained through 7 days. In a further animal model, 12 pockets were created in 6 rabbits, for CIED insertion with and without T3 envelopes, to evaluate efficacy against gram+ and gram- bacteria. At day 7, implant sites were evaluated for signs of infection via macroscopic observations and microbial recovery procedures. A Fisher’s Exact Test was used for comparisons.

Results

The T3 envelope showed a similar elution profile to T2 in vitro (Figure) with f2 >50 (range 76-84). In the in vivo assessment, the T3 envelope eluted both antibiotics above the MIC at 2hr post-implant with sustained elution through 7 days, consistent with historical T2 performance. Further bacterial challenge studies in vivo showed a statistically significant reduction (p<0.05) in infections with 0/6 infected pockets in the CIED + T3 group vs 6/6 infected pockets in the CIED only group consistent with T2 performance (Table).

Conclusion

The 3rd generation absorbable antibacterial envelope demonstrated equivalent pre-clinical performance compared to the 2nd generation envelope as antibiotic elution curves were equivalent, elution was sustained at concentrations above MIC for 7 days, and infection rates were significantly reduced compared to no envelope. These results suggest equivalent clinical performance could be expected with the newly designed envelope.

Peripheral Blood Monocyte Abundance Predicts Outcomes in Patients with Breast Cancer

Biomarkers of response are needed in breast cancer to stratify patients to appropriate therapies and avoid unnecessary toxicity. We used peripheral blood gene expression and cell type abundance to identify biomarkers of response and recurrence in neoadjuvant chemotherapy treated breast cancer patients. We identified a signature of interferon and complement response that was higher in the blood of patients with pathologic complete response. This signature was preferentially expressed by monocytes in single cell RNA sequencing. Monocytes are routinely measured clinically, enabling examination of clinically measured monocytes in multiple independent cohorts. We found that peripheral monocytes were higher in patients with good outcomes in four cohorts of breast cancer patients. Blood gene expression and cell type abundance biomarkers may be useful for prognostication in breast cancer.

Significance

Biomarkers are needed in breast cancer to identify patients at risk for recurrence. Blood is an attractive site for biomarker identification due to the relative ease of longitudinal sampling. Our study suggests that blood-based gene expression and cell type abundance biomarkers may have clinical utility in breast cancer.

245 Host myeloid response to tumor and immunotherapy is associated with heterogeneity in outcomes to anti-PDL1

Background

Immune checkpoint inhibitors (ICI) improve patient survival in some cancer types but yield limited success in breast cancer. Phase-III clinical trials in triple-negative breast cancer (TNBC) patients, who harbor extensive tumor-infiltrating lymphocytes, demonstrate increased progression-free survival (IMpassion130) and pathologic complete response (KEYNOTE-522). Consequently, combinations of ICI and chemotherapy have been FDA-approved for metastatic TNBC patients. However, the therapeutic benefit of ICI alone and the most efficacious chemotherapy combinations are poorly characterized. We sought to model ICI response in vivo to elucidate the mechanisms of immunotherapy efficacy in breast cancer and ascertain the therapeutic benefits of different chemotherapeutic combinations with ICI.

Methods

Using an immunocompetent EMT6 orthotopic mammary tumor model, we investigated the efficacy of single-agent immunotherapy and in combination with standard-of-care chemotherapy (paclitaxel [PAC] or doxorubicin [DOX]). We used single-cell RNA sequencing and bulk RNA and T-cell receptor (TCR) sequencingto assess the cellular landscape of the primary tumor in response to combinatorial therapeutic strategies and identify systemic genetic alterations and T-cell expansion, respectively.

Results

Single-agent anti-PD-L1 robustly suppressed primary tumor growth (p =0.0046) and extended survival (p<0.0001) beyond the isotype control. Chemotherapy demonstrated moderate therapeutic efficacy without potentiating the benefit of single-agent anti-PD-L1. Interestingly, despite using a genetically identical murine tumor model/host, anti-PD-L1 induced heterogeneous responses, from complete response to intrinsic resistance. Longitudinal analysis of peripheral blood from heterogeneously responding mice uncovered myeloid cell recruitment signatures corresponding to transient responses ultimately converting to resistance. We identified specific clonal T cell expansion present only in responders. Single-cell transcriptomic profiling of the tumor microenvironment revealed increased T cells and natural killer cells and reduced regulatory T cells in the combination groups versus chemotherapy alone, although this did not translate into improved benefit. Gene-set enrichment analysis on infiltrating T cells identified a robust signature of cytotoxic T cell activation characterized by a significant enrichment in inflammatory pathways in both single-agent anti-PD-L1 and in combination with chemotherapy.

Conclusions

We identify a heterogeneously ICI-responsive in vivo model that emulates TNBC patient response to combinatorial ICI approaches. We describe single-agent ICI efficacy in upregulating cytotoxic immune cell infiltration and expansion within the primary tumor that diminishes tumor growth and enhances survival. Moreover, this study describes differential responses in a genetically similar host, which reflects heterogeneous patient response to ICI. Further characterization may identify systemic biomarkers and tumor antigen-specific T cell clones to accurately predict immunotherapy response in patients and uncover mechanisms for sensitizing refractory tumors to ICI

756 Identifying the role of B7-H4 as a suppressor of tumor infiltrating lymphocytes and a target for immunotherapy in breast cancer

Background

Immune checkpoint inhibitors (ICI) have improved patient survival in some cancer types but yielded limited success in breast cancer. Combinations of ICI (αPD-L1/PD-1) and chemotherapy have been FDA-approved for metastatic TNBC patients, and potentially in the early breast cancer setting, but many patients remain non-responsive to ICI. B7-H4 is a B7 family ligand with proposed immunosuppressive functions being explored as a cancer immunotherapy target and may be associated with resistance to αPD-L1. We confirmed an inverse expression pattern between B7-H4 and PD-L1 in breast tumor cells, which has previously been noted by others. B7-H4 was expressed in immune-excluded tumors, while PD-L1 was expressed in immune-infiltrated tumors. Based on these findings, we hypothesized ectopic B7-H4 expression would induce αPD-L1 resistance through immune cell suppression in vivo.

Methods

Using an immunocompetent and αPD-L1-sensitive EMT6 orthotopic mammary cancer model, we induced ectopic expression of B7-H4 and performed animal survival studies to assess therapy response, and RNA analysis to assess changes to cell signaling among tumor infiltrating immune cells. Finally, we performed transcriptomic correlation analyses from the cancer cell line encyclopedia dataset to identify potential regulators of B7-H4 in breast cancer.

Results

In the αPD-L1-sensitive EMT6 mammary cancer model, tumors with cell-surface B7-H4 expression were more resistant to immunotherapy. Additionally, tumor infiltrating immune cells had reduced immune activation signaling based on transcriptomic analysis. We also observed strong correlation with B7-H4 mRNA and epithelial cell markers, in contrast to gene expression markers of mesenchymal cells.

Conclusions

Our data support the hypothesis that B7-H4 induces tumor resistance to αPD-L1 ICI through an immunosuppressive function. Additionally, the strong correlation of B7-H4 to epithelial cell markers suggests a potential regulatory mechanism of B7-H4 expression independent of PD-L1 regulation.

318 Enforced tumor specific MHC-I heterogeneity in triple negative breast cancer drives immunotherapy resistance

Background

Despite the broad success of immune checkpoint inhibition (ICI e.g. anti-Programmed Death Ligand-1 [PD-L1]) in cancer treatment, tumor-intrinsic factors leading to intrinsic and acquired resistance are poorly understood. Tumor specific MHC-I expression is indispensable for anti-PD-1/L1 response as complete loss of MHC-I via B2M deletion results in inability of CD8+ T cells to recognize tumor-associated antigens. However, MHC-I is heterogeneously downregulated or lost in many tumor types. Tumor cell destruction can also occur through non-synaptic mechanisms, in a so-called ‘field effect’. Therefore, we modeled heterogeneous loss of MHC-I expression in breast cancer and experimentally evaluated how heterogeneous MHC-I loss affects response to anti-PD-L1 therapy.

Methods

We performed quantitative immunofluorescence for MHC-I and Pan-CK on breast cancer tumors (n=410). To determine the functional effect of MHC-I heterogeneity on anti-PD-L1 response, we used an immunocompetent EMT6 orthotopic mammary tumor model which ubiquitously expresses MHC-I at baseline. Using CRISPR/Cas9, we engineered EMT6 cells with B2m loci excision resulting in complete knockout of MHC-I on the cell surface. We then orthotopically implanted B2m-comtetent and B2m-KO cells at varying inoculum ratios (100:0, 90:10, 50:50, 10:90, 0:100) into syngeneic Balb/C mice and assessed immune responsiveness and efficacy of checkpoint inhibition. Additionally, to look at how loss of MHC-I affects the tumor microenvironment we will use the PanCancer Immune NanoString panel (n=770 genes) to evaluate gene expression patterns in tumor cells and infiltrating immune cells.

Results

In patient samples, we identified high diversity in MHC-I expression across all clinical subtypes, with triple negative breast cancer (TNBC) having the highest MHC-I expression. Chemotherapy-treated tumors had higher MHC-I levels than untreated tumors. In mice when 10% of cells were B2m-KO, we observed a 50% reduction in complete eradication of EMT6 tumors with aPD-L1 treatment and reduced disease-stabilization and no complete responses when a 50% mixture of MHC-I deficient cells. An increasing percentage of B2m KO leads to worse outcomes overall and a decrease in infiltrating T cells.

Conclusions

Our work suggests that there is an ICI-responsive phenotype that is driven by heterogeneity in MHC-I expression levels. As little as 10% of tumor specific MHC-I loss can lead to therapeutic resistance and a decrease in complete responders. This represents that early TNBC may be less responsive to single-agent PD-L1 due to specific percentages of MHC-I loss. MHC-I expression can influence therapy outcomes and potentially lead to novel observations of how to overcome lack of, or limited, MHC-I expression.

Tumor-Specific Major Histocompatibility-II Expression Predicts Benefit to Anti-PD-1/L1 Therapy in Patients With HER2-Negative Primary Breast Cancer

PURPOSE

Immunotherapies targeting PD-1/L1 enhance pathologic complete response (pCR) rates when added to standard neoadjuvant chemotherapy (NAC) regimens in early-stage triple-negative, and possibly high-risk estrogen receptor-positive breast cancer. However, immunotherapy has been associated with significant toxicity, and most patients treated with NAC do not require immunotherapy to achieve pCR. Biomarkers discerning patients benefitting from the addition of immunotherapy from those who would achieve pCR to NAC alone are clearly needed. In this study, we tested the ability of MHC-II expression on tumor cells, to predict immunotherapy-specific benefit in the neoadjuvant breast cancer setting.

PATIENTS AND METHODS

This was a retrospective tissue-based analysis of 3 cohorts of patients with breast cancer: (i) primary nonimmunotherapy-treated breast cancers (n = 381), (ii) triple-negative breast cancers (TNBC) treated with durvalumab and standard NAC (n = 48), and (iii) HER2-negative patients treated with standard NAC (n = 87) or NAC and pembrolizumab (n = 66).

RESULTS

HLA-DR positivity on ≥5% of tumor cells, defined a priori, was observed in 10% and 15% of primary non-immunotherapy-treated hormone receptor-positive and triple-negative breast cancers, respectively. Quantitative assessment of MHC-II on tumor cells was predictive of durvalumab + NAC and pembrolizumab + NAC (ROC AUC, 0.71; P = 0.01 and AUC, 0.73; P = 0.001, respectively), but not NAC alone (AUC, 0.5; P = 0.99).

CONCLUSIONS

Tumor-specific MHC-II has a strong candidacy as a specific biomarker of anti-PD-1/L1 immunotherapy benefit when added to standard NAC in HER2-negative breast cancer. Combined with previous studies in melanoma, MHC-II has the potential to be a pan-cancer biomarker. Validation is warranted in existing and future phase II/III clinical trials in this setting.

Feasibility, preliminary efficacy, and accessibility of a twitter-based social support group vs Fitbit only to decrease sedentary behavior in women

BACKGROUND

Health behavior change interventions delivered by social media allow for real-time, dynamic interaction, peer social support, and experimenter-provided content.

AIMS

We tested the feasibility, acceptability, and preliminary efficacy of a novel Twitter-based walking break intervention with daily behavior change strategies and prompts for social support, combined with a Fitbit, vs. Fitbit alone.

METHODS

In a 2-group pilot, 45 sedentary women from a heart clinic were randomized to Twitter + Fitbit activity tracker (Tweet4Wellness, n = 23) or Fitbit-only (control, n = 22). All received a Fitbit and 13 weeks of tailored weekly step goals. Tweet4Wellness consisted of a private Twitter support group, with daily automated behavior change "tweets" informed by behavior change theory, and encouragement to communicate within the group. Feasibility outcomes included recruitment and enrollment numbers, implementation challenges, and number and type of help requests from participants throughout the study period. Preliminary efficacy outcomes provided by Fitbit data were sedentary minutes, number of hours with >250 steps, maximum sitting bout, weighted sedentary median bout length, total steps, intensity minutes (>3.0 METS), and ratio of time spent sitting-to-moving. Acceptability outcomes included level of Twitter participation within Tweet4Wellness, and Likert scale plus open-ended survey questions on enjoyment and perceived effectiveness of intervention components. Survey data on acceptability of the features of the intervention were collected at 13 weeks (end-of-treatment [EOT]) and 22 weeks (follow-up).

RESULTS

The study was feasible, with addressable implementation challenges. Tweet4Wellness participants changed significantly from baseline to EOT relative to control participants on number of active hours p = .018, total steps p = .028, and ratio of sitting-to-moving, p = .014. Only sitting-to-moving was significant at follow-up (p = .047). Among Tweet4Wellness participants, each tweet sent during treatment was associated with a 0.11 increase in active hours per day (p = .04) and a 292-step increase per day (p < .001). Tweet4Wellness participants averaged 54.8 (SD = 35.4) tweets, totaling 1304 tweets, and reported liking the accountability and peer support provided by the intervention.

CONCLUSION

A Twitter-delivered intervention for promoting physical activity among inactive women from a heart clinic was feasible, acceptable, and demonstrated preliminary efficacy in increasing daily active hours, daily total steps, and the ratio of sitting-to-moving from pre to post for the intervention compared with the control. Lessons learned from this pilot suggest that the next study should expand the recruitment pool, refine the intervention to increase group engagement, and select active hours, total steps, and ratio of sitting-to-movement as primary sedentary behavior measures.

Analysis of the Motional Stark Effect (MSE) diagnostic to measure the rotational transform and current profile in the Large Helical Device

The analysis method of the Motional Stark Effect (MSE) diagnostic to measure the rotational transform and current profiles in the Large Helical Device has been improved. This was done by using the Variational Moments Equilibrium Code to calculate an equilibrium database for various pressure profiles and current profiles. This method looks for the radial profile of the rotational transform in the equilibrium database that gives the best fit to the polarization angle profiles measured with the MSE diagnostic. This analysis improves the measurements of rotational transform, especially near the magnetic axis, where the sensitivity of the polarization angle measurements becomes low and the uncertainty due to error in the estimation of the Pfirsch-Schlüter current becomes large. The radial profiles of the rotational transform and current profiles for Electron Cyclotron Current Drive and Neutral Beam Current Drive are obtained in the new analysis method with a sufficiently high accuracy to discuss the discrepancy of the current density profiles between the measurements and the calculations.

Abstract PS4-19: Evaluation of tumor-specific MHC-II expression as a biomarker

Recently MHC-II protein expression levels in breast cancer tumor cells were shown to predict response to the PD-1 inhibitor pembrolizumab on a neoadjuvant clinical trial for ER+ and TNBC (ISPY-2). To better understand this biomarker and avoid post-market issues, we aimed to investigate possible pitfalls of MHC-II/HLA-DR quantification, prevalence of HLA-DR expression in breast cancer (BC) cells and its association with clinical data in a cohort of 372 BC patents. We assessed tumor and non-tumor HLA-DR expression by multiplex fluorescence immunohistochemistry on 8 TMAs containing 372 surgical BC samples, comprised of 239 ER+ and 123 TNBCs. Patient characteristics are shown in table 1. PanCK was used to define the tumor area and HLA-DR quantification was performed by training an object classifier on QuPath. Upon visual examination, 23 samples showed patchy panCK expression. We excluded normal breast epithelium and in situ components, which showed varying degrees of HLA-DR. 44.4% of breast cancers expressed HLA-DR, with 8.3% showing high tumor expression (HLA-DRHI; ≥20% of tumor cells). TNBC showed higher prevalence of HLA-DRHI cases (35% HLADR+, 14.6% HLA-DRHI, mean tumor HLA-DR expression (% of tumor cells) 10.3%, range 0-84%) than ER+ BC (51% HLADR+, 5.4% HLA-DRHI, mean 7.4%, range 0-66.5%). In some cases, HLA-DR and panCK expression were mutually exclusive. In other cases the lack of panCK expression highlighted the presence of stromal cells within the tumor area that were not evident on H&E. Tumoral MHC-II expression correlated with the presence of TILs for ER+ BC (r=0.18, p=0.0158) and TNBC (r=0.20, p= 0.0450), specifically CD3 (r=0.49 p&lt;0.0001) and CD4 (r=0.48 p&lt;0.0001), and to a lesser extent CD8 (r=0.28, p= 0.013) in a subset of TNBCs on which these stains where performed (n=81). We found no correlation between tumoral MHC-II expression and clinical characteristics (ER and PR within ER+ BC, age, presence of lymph node metastasis, stage, neoadjuvant treatment) in ER+ or TNBC. High tumor HLA-DR expression correlated with poorer recurrence-free survival (RFS) in ER+ BC (p=0.038) but showed no correlation in TNBC. Cox proportional hazard model including clinical data determined that only stage was an independent predictor of survival in ER+. Non-tumoral HLA-DR expression was associated with better RFS (p=0.007) and overall survival (p=0.01) in TNBC; however, only stage was an independent predictor in multivariant analyses. Tumor MHC-II expression in BC has been reported to range from 22% to 48.5% in TNBC or unselected BC, and high tumoral MHC-II expression was reported to be 6.9% in unselected BC and 36.3% in TNBC. Specific rates of HLA-DR expression in ER+ breast cancer have not been extensively investigated. Here we report a similar overall prevalence, but lower number of tumors presenting high HLA-DR expression and an association with poorer survival in ER+ BC. HLA-DR IHC is a robust assay that can be easily used to identify MCH-II high expressing tumors and scoring percentage of tumoral cells should be more reproducible than PD-L1 scoring on immune cells when assessed by a trained pathologist.

Table 1: Patient characteristicsTNBCER+Total number of cases239123Median age48,563Treatmenttreatment naïve26%45%neoadjuvant chemotherapy74%4%pre-surgical letrozole-51%Positive lymph node58%14%StageI27%82%II20%27%III67%8%IV0%1%

Citation Format: Paula Ines Gonzalez Ericsson, Justin M Balko, Violeta Sanchez, Melinda Sanders. Evaluation of tumor-specific MHC-II expression as a biomarker [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS4-19.

0180 Sleep, Sleepiness, and Sleep Hygiene Related to Nomophobia (No Mobile Phone Phobia)

Introduction

Previously, active phone use at bedtime has been implicated in disrupted sleep and related complaints. To improve sleep, a recommendation following such findings is limiting phone use before and during bedtime. However, for those with the characteristic of “nomophobia”, fear of being out of mobile phone contact, this recommendation could exacerbate anxiety at and around bedtime and disrupt, rather than improve, sleep. In 2012, an estimated 77% of 18-24-year-olds could be identified as nomophobic. Because of the prevalence of nomophobia and its possible interaction with sleep, we explored the existence of nomophobia in a college-age population and its relationship to sleep, sleepiness, and sleep hygiene behaviors.

Methods

327 university students (age: M=19.7 years, SD=3.78) recruited from introductory psychology courses and campus newsletters were given extra credit or a chance to win $25 gift cards for participation. Participants completed demographic information, the Nomophobia Questionnaire (NMP-Q), the Epworth Sleepiness Scale (ESS), the Pittsburgh Sleep Quality Index, questions regarding associated features of inadequate sleep hygiene, and the Sleep Hygiene Index. Additional sleep hygiene questions assessed frequency of active and passive technology use during sleep time.

Results

89.4% of the participants had moderate or severe nomophobia. Greater nomophobia was significantly related to greater daytime sleepiness (ESS) (r(293)=.150, p&lt;.05), associated features of poor sleep (daytime sleepiness: r(297)=.097, p&lt;.05, and avolition: r(297)=.100, p&lt;.05), more maladaptive sleep hygiene behaviors including active technology use during sleep time (r(298)=.249, p&lt;.05), long daytime naps, inconsistent wake and bed times, using bed for non-sleep purposes, uncomfortable bed, and bedtime cognitive rumination (r’s=0.097 to 0.182).

Conclusion

Most participants experienced moderate to severe nomophobia with greater nomophobia associated with greater sleepiness, avolition, and poorer sleep hygiene. Nomophobia is likely to be an important consideration when treating sleep disorders and/or making any sleep hygiene recommendations.

Support

Hendrix College Charles Brewer Fund for Psychology

0194 Bedtime Technology Use and New Questions for the Sleep Hygiene Index

Introduction

We examined the relationship between bedtime active and passive social technology use (self and bedpartner) and daytime sleepiness/sleep. We generated questions to differentiate participants with and without bedpartners and updated passive personal, active bedpartner, and passive bedpartner social technology questions of the Sleep Hygiene Index.

Methods

327 students (age: M=19.7 years, SD=3.78) recruited through psychology courses and campus newsletters received extra credit or chances to win $25 gift cards. Participants completed demographic information, the Epworth Sleepiness Scale (ESS), the Pittsburgh Sleep Quality Index, questions regarding associated features of inadequate sleep hygiene, and the Sleep Hygiene Index. Five questions assessed active and passive social technology use, presence of a bedpartner, and awareness of bedpartner active and passive social technology use during sleep time.

Results

61.8% and 62.7% of students reported frequently or always using active and passive bedtime social technology, respectively; and 23.5% and 29.1% reported noticing a partner’s active or passive use. More frequent active technology use was significantly related to greater daytime sleepiness (ESS) (r(305)=.193, p&lt;.05), sleep disturbances (PSQI-global: r(302)=.120, p&lt;.05), and associated features of inadequate sleep hygiene (daytime sleepiness, worry about sleep, mood disturbance, avolition, and reduced cognition (r(306)=.212, p&lt;.05)). Neither passive use nor passive or active partner use was significantly related to any sleep/sleepiness variables.

Conclusion

We continue to find students are frequent users of bedtime social technology which is related to daytime sleepiness, disrupted sleep, and related complaints. Passive and partner active/passive bedtime technology use may not have a significant impact on daytime sleepiness. It is possible younger participants are not good judges of passive or partner technology use or this younger population is resilient to these disruptions.

Support

none

The path to a better biomarker: application of a risk management framework for the implementation of PD-L1 and TILs as immuno-oncology biomarkers in breast cancer clinical trials and daily practice

Immune checkpoint inhibitor therapies targeting PD-1/PD-L1 are now the standard of care in oncology across several hematologic and solid tumor types, including triple negative breast cancer (TNBC). Patients with metastatic or locally advanced TNBC with PD-L1 expression on immune cells occupying ≥1% of tumor area demonstrated survival benefit with the addition of atezolizumab to nab-paclitaxel. However, concerns regarding variability between immunohistochemical PD-L1 assay performance and inter-reader reproducibility have been raised. High tumor-infiltrating lymphocytes (TILs) have also been associated with response to PD-1/PD-L1 inhibitors in patients with breast cancer (BC). TILs can be easily assessed on hematoxylin and eosin-stained slides and have shown reliable inter-reader reproducibility. As an established prognostic factor in early stage TNBC, TILs are soon anticipated to be reported in daily practice in many pathology laboratories worldwide. Because TILs and PD-L1 are parts of an immunological spectrum in BC, we propose the systematic implementation of combined PD-L1 and TIL analyses as a more comprehensive immuno-oncological biomarker for patient selection for PD-1/PD-L1 inhibition-based therapy in patients with BC. Although practical and regulatory considerations differ by jurisdiction, the pathology community has the responsibility to patients to implement assays that lead to optimal patient selection. We propose herewith a risk-management framework that may help mitigate the risks of suboptimal patient selection for immuno-therapeutic approaches in clinical trials and daily practice based on combined TILs/PD-L1 assessment in BC. © 2020 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Association of tumor-infiltrating lymphocytes with distant disease-free survival in the ShortHER randomized adjuvant trial for patients with early HER2+ breast cancer

BACKGROUND

There is the need to identify new prognostic markers to refine risk stratification for HER2-positive early breast cancer patients. The aim of this study was to evaluate the association of tumor-infiltrating lymphocytes (TILs) with distant disease-free survival (DDFS) in patients with HER2-positive early breast cancer enrolled in the ShortHER adjuvant trial which compared 9 weeks versus 1-year trastuzumab in addition to chemotherapy, and to test the interaction between TILs and treatment arm.

PATIENTS AND METHODS

Stromal TILs were assessed for 866 cases on centralized hematoxylin and eosin-stained tumor slides. The association of TILs as 10% increments with DDFS was assessed with Cox models. Kaplan-Meier curves were estimated for patients with TILs ≥20% and TILs <20%. Median follow-up was 6.1 years.

RESULTS

Median TILs was 5% (Q1-Q3 1%-15%). Increased TILs were independently associated with better DDFS in multivariable model [hazard ratio (HR) 0.73, 95% confidence interval (CI) 0.59-0.89, P = 0.006, for each 10% TILs increment]. Five years DDFS rates were 91.1% for patients with TILs <20% and 95.7% for patients with TILs ≥20% (P = 0.025). The association between 10% TILs increments and DDFS was significant for patients randomized to 9 weeks of trastuzumab (HR 0.60, 95% CI 0.41-0.88) but not for patients treated with 1 year of trastuzumab (HR 0.89, 95% CI 0.71-1.12; test for interaction P = 0.088). For patients with TILs <20%, the HR for the comparison between the short versus the long arm was 1.75 (95% CI 1.09-2.80, P=0.021); whereas, for patients with TILs ≥20% the HR for the comparison of short versus long arm was 0.23 (95% CI 0.05-1.09, P = 0.064), resulting in a significant interaction (P = 0.015).

CONCLUSIONS

TILs are an independent prognostic factor for HER2-positive early breast cancer patients treated with adjuvant chemotherapy and trastuzumab and may refine the ability to identify patients at low risk of relapse eligible for de-escalated adjuvant therapy.

Noninvasive Follicular Thyroid Neoplasm With Papillary-Like Nuclear Features in Children: An Institutional Experience and Literature Review

BACKGROUND

Papillary thyroid carcinoma (PTC) in children has a distinctive set of clinicopathologic features and molecular signature compared to their adult counterparts. The recent recommendation to reclassify encapsulated follicular variant of papillary thyroid carcinoma (EFVPTC) without invasion as noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) is based on evidence derived almost exclusively from studies in adults. Clinicopathologic studies restricted to pediatric NIFTP are limited.

METHODS

We retrospectively analyzed all pediatric PTC and NIFTP diagnosed and treated in our institution from 1999 to 2016 (n = 31).

RESULTS

Using recently published consensus diagnostic criteria, we identified 3 NIFTP and 2 infiltrative follicular variants of papillary thyroid carcinoma (FVPTC) among 31 cases. Two of the NIFTP cases were initially diagnosed as EFVPTC. All 3 patients with NIFTP had unifocal tumors of lower American Joint Committee on Cancer (AJCC) classification (T2 or lower) and were free of lymph node or distant metastasis. Total (n = 1) or completion (n = 2) thyroidectomy was performed in all cases, and only 1 NIFTP patient received subsequent radioablative therapy. No residual or recurrent disease has been observed during follow-up (15-138 months) in patients with NIFTP.

CONCLUSIONS

Our experience with NIFTP in children is similar to outcomes reported in adult studies, suggesting that pediatric NIFTP behave indolently as evidenced by the absence of local recurrence in our cohort.

Abstract GS6-06: A neoadjuvant trial with letrozole identifies PRR11 in the 17q23 amplicon as a mechanism of resistance to endocrine therapy in ER-positive breast cancer

Although the 17q23 amplicon has been associated with luminal B breast cancer (BC) and high risk of recurrence, a specific gene or genes in this region that would be causal to endocrine resistance have not yet been uncovered. We performed whole transcriptome analysis on RNA extracted from 58 estrogen receptor (ER)+ BCs treated with neoadjuvant letrozole for median 7.2 months. PRR11 (Proline rich 11), located in 17q23, was upregulated in non-responding tumors as defined by relapse after a median follow up of 5 years and/or a preoperative endocrine prognostic index (PEPI) ≥4. Differential gene expression analysis between tumors expressing low vs high PRR11 mRNA showed that BC signatures associated with proliferation, IGF-1 and PI3K signaling were enriched in tumors with high PRR11 expression.

Rate of PRR11 amplification is 15.2% in the Metastatic Breast Cancer project, but 9.5% and 9.4% in METABRIC and The Cancer Genome Atlas (TCGA), respectively. Gene Set Enrichment Analysis revealed an enrichment of hallmark gene sets associated with proliferation in PRR11-amplified ER+ BCs in METABRIC and TCGA. Integrated analysis of gene expression with on-treatment Ki67 levels from three independent studies with operable ER+ BCs treated with neoadjuvant aromatase inhibitor (ACOSOG-Z1031, NCT00651976, Llombart-Cussac et al.) showed that PRR11 was the only gene in 17q23 with a significant correlation with a high Ki67 levels across all studies.

PRR11 knockdown inhibited E2-independent growth of HCC1428 LTED (long-term estrogen deprived) and MCF7 LTED cells in culture and MCF7 xenografts. PRR11 siRNA also inhibited growth of fulvestrant-resistant and tamoxifen-resistant MCF7 cells. Conversely, PRR11 transduction induced MDA-MB-134VI cell growth under estrogen-depleted conditions. Using a PCR array with 84-cell cycle genes, we identified SKP2, CDKN1A, CCNB2, CCNA2, CKS2 and CCNB1 as genes downregulated by PRR11 knockdown. Except for SKP2 and CDKN1A, expression of all those genes was elevated in PRR11-amplifiedER+ BCs in TCGA and METABRIC.

Suggesting a link to activation of PI3K signaling, we found the proline-rich motif of PRR11 associates with the SH3 domain of the p85 regulatory subunit of PI3K. We hypothesized that this association suppresses p85 homodimer formation, thus facilitating binding of PI3Kα (p110α)-p85 dimers to IRS1, retention of p110α at the plasma membrane and, hence, activation of PI3K/AKT. To test this, we co-transfected HEK293T cells with HA-p85 and FLAG-p85. Forced expression of PRR11 reduced HA-p85 and FLAG-p85 homodimers as shown by HA and FLAG pulldowns followed by FLAG and HA immunoblots, respectively. PRR11 overexpression enhanced insulin-stimulated association of IRS1 to p110α and activation of AKT. PRR11 knockdown reduced insulin/IGF-1/2-stimulated p-AKT. In METABRIC and TCGA, PRR11 amplification and PIK3CA mutations are exclusive of each other, suggesting these alterations would be functionally linked with the same pathway.

Connectivity map analysis with the list of genes significantly overexpressed in ER+/PRR11-amplified BCs predicted PI3K inhibitors as perturbations that suppress such gene list. In the MGH/Sanger dataset, PRR11-amplified BC cell lines displayed significantly higher sensitivity to the pan-PI3K inhibitor pictilisib compared to cell lines without PRR11 amplification. Finally, inhibition of PI3Kα by siRNA or alpelisib abrogated E2-independent growth and insulin-stimulated growth of PRR11-transduced MDA-MB-134VI and MCF10A cells, respectively, suggesting p110α is required for the growth promoting effects of PRR11.

These data suggest that 1) PRR11 is a mediator of resistance to antiestrogens via amplification of PI3K/AKT signaling, and 2) PI3Kα is a potential therapeutic target in ER+ BCs harboring PRR11 amplification.

Citation Format: Kyung-min Lee, Angel Guerrero-Zotano, Ariella Hanker, Alberto Servetto, Dhivya Sudhan, Luigi Formisano, Valerie Jansen, Paula González-Ericsson, Melinda Sanders, Thomas Stricker, Lewis Cantley, Carlos Arteaga. A neoadjuvant trial with letrozole identifies PRR11 in the 17q23 amplicon as a mechanism of resistance to endocrine therapy in ER-positive breast cancer [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr GS6-06.

High-risk human papilloma virus testing in oropharyngeal squamous cell carcinoma at a university-based cancer center: A quality improvement project

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Background: Although traditionally linked to smoking and alcohol, high-risk (HR) human papilloma virus (HPV) associated head and neck cancers are becoming increasingly common in non-smokers. HR HPV causes approx. 70% of all oropharyngeal squamous cell carcinomas (OPSCC) and they have better outcomes when compared with smoking associated OPSCC. An accurate HPV assessment in OPSCC is important due to its relevance in treatment and follow up. This Quality Improvement project was designed to evaluate frequency of HPV testing with p16 immunochemistry (IHC) staining in patients with OPSCC at a University-based cancer center. Methods: All cases diagnosed with OPSCC or those with high suspicion for OPSCC between 2008 and 2017 were obtained from Department of Pathology. Patients with biopsies from sites other than oropharynx as well as those with biopsies performed at outside hospitals were excluded. All pathology reports were reviewed to identifyfrequency of p16 IHC staining. Results: A list of 127 cases was obtained from Pathology. Of these, 26 non-OPSCC and external hospital slides were excluded, making sample size (n) 101. HR HPV testing by p16 IHC staining was performed in 42 of 101 patients (41.5%) and not performed in 59 (58.5%). 38 of 42 patients tested were positive for HR HPV (90.5%). There was an overall upward trend in the frequency of HPV testing over the 10 years. Conclusions: HR HPV testing was done only in 41.5% of eligible patients suggesting a deficiency in testing for this biomarker. Various causes for this lack of testing were identified, most common one being inadequacy of tissue specimen. 90.5% of eligible patients tested were positive for HR-HPV, highlighting the strong association between HPV and OPSCC. Based on importance of testing HR HPV in OPSCC and need for aligning with American Society of Clinical Pathology guidelines, corrective actions were proposed by meeting with pathologists and otolaryngologists.

Accuracy and precision of non-invasive cardiac output monitoring by electrical cardiometry: a systematic review and meta-analysis

Cardiac output monitoring is used in critically ill and high-risk surgical patients. Intermittent pulmonary artery thermodilution and transpulmonary thermodilution, considered the gold standard, are invasive and linked to complications. Therefore, many non-invasive cardiac output devices have been developed and studied. One of those is electrical cardiometry. The results of validation studies are conflicting, which emphasize the need for definitive validation of accuracy and precision. We performed a database search of PubMed, Embase, Web of Science and the Cochrane Library of Clinical Trials to identify studies comparing cardiac output measurement by electrical cardiometry and a reference method. Pooled bias, limits of agreement (LoA) and mean percentage error (MPE) were calculated using a random-effects model. A pooled MPE of less than 30% was considered clinically acceptable. A total of 13 studies in adults (620 patients) and 11 studies in pediatrics (603 patients) were included. For adults, pooled bias was 0.03 L min^-1 [95% CI - 0.23; 0.29], LoA - 2.78 to 2.84 L min^-1 and MPE 48.0%. For pediatrics, pooled bias was - 0.02 L min^-1 [95% CI - 0.09; 0.05], LoA - 1.22 to 1.18 L min^-1 and MPE 42.0%. Inter-study heterogeneity was high for both adults (I² = 93%, p < 0.0001) and pediatrics (I² = 86%, p < 0.0001). Despite the low bias for both adults and pediatrics, the MPE was not clinically acceptable. Electrical cardiometry cannot replace thermodilution and transthoracic echocardiography for the measurement of absolute cardiac output values. Future research should explore it's clinical use and indications.

Full-term newborn infant with blistering skin lesions-Caution regarding use of pain medications

Multiple opioids are known to trigger mast cell degranulation. We report the case of a neonate with blistering skin lesions at birth who died of multi-organ failure after administration of morphine. Given the excessive histamine release and potential complications associated with morphine administration, alternative opioids and adjuvants should be considered in infants presenting with evidence of bullous or infiltrative skin lesions until mastocytosis is ruled out.

[Practice of parenting and related factors on children aged 0-5 in the urban areas of China]

Objective: To characterize the relations between the practice of parenting and associated factors on children (0-5 years old) in urban areas of China, in order to provide evidence for promoting the early development of children and to provide positive guidance and service programs on parenting. Methods: A total of 4 515 parents from 15 cities (14 provinces) were surveyed with a self-administered questionnaire. Parenting and Family Adjustment Scales (PAFAS) was used, including parameters as: consistency and coercive parenting, positive encouragement, parent-child relationship and parental emotion adjustment, family relationship and parental teamwork aspects, etc. Both single factor analysis and multiple linear regression were used to examine the associations between parenting practice, individual, parental and family factors. Results: The mean score of PAFAS was 21.00 (15.00-28.00), associated with factors as children's age, only-child family, premature delivery, father's education level, confidence on parenting, problems regarding the parental mood, annual family income, family structure and behavior on seeking professional help, etc. Results showed that there were big differences on the practice of parenting in China and influenced by variety of factors. Conclusions: The general situation of parenting was well, in the urban areas of China. The practice of parenting was associated with a series of individual, parental and family factors. Programs on improving the parenting skills and promoting the early development of children, should be highlighted.

Homogeneous reduced moment in a gapful scalar chiral kagome antiferromagnet

We present a quantitative experimental investigation of the scalar chiral magnetic order with in Nd3Sb3Mg2O14. Static magnetization reveals a net ferromagnetic ground state, and inelastic neutron scattering from the hyperfine coupled nuclear spin reveals a local ordered moment of 1.76(6) μ B , just 61(2)% of the saturated moment size. The experiments exclude static disorder as the source of the reduced moment. A 38(1) μ eV gap in the magnetic excitation spectrum inferred from heat capacity rules out thermal fluctuations and suggests a multipolar explanation for the moment reduction. We compare Nd3Sb3Mg2O14 to Nd pyrochlores and show that Nd2Zr2O7 is in a spin fragmented state using nuclear Schottky heat capacity.

A forced-choice preferential looking task for the assessment of vision in dogs: pilot study

OBJECTIVES

To describe preliminary use of a forced-choice preferential looking task for the clinical assessment of vision in dogs.

MATERIALS AND METHODS

The vision of 18 pet dogs was investigated in two separate studies using a forced-choice preferential looking task: multiple observers watched eye, head and body movements on video recordings to identify cues suggesting when a dog had seen the feature of interest. Human observer reliability was determined using eight dogs and computer-generated stimuli. Visual acuity was assessed using computer-generated grating stimuli: in real-time, an observer watched each dog's eye movement patterns and behaviour to decide whether each grating was seen. Stimuli were presented in a step-wise manner and were controlled by the observer. Acuity was estimated as the highest spatial frequency the dog was determined to have seen.

RESULTS

Median estimated visual acuity was better at 1 m compared to that at 3 m. Average test time was longer at a 3-m distance than at 1 m. Inter- and intra-observer reliability was better from 1 m than from 3 m.

CLINICAL SIGNIFICANCE

Preliminary use of a forced-choice preferential looking task for measurement of visual acuity in dogs has potential use as a clinical tool for the assessment of vision in dogs.

Extended Adjuvant Therapy with Neratinib Plus Fulvestrant Blocks ER/HER2 Crosstalk and Maintains Complete Responses of ER+/HER2+ Breast Cancers: Implications to the ExteNET Trial

PURPOSE

The phase III ExteNET trial showed improved invasive disease-free survival in patients with HER2⁺ breast cancer treated with neratinib versus placebo after trastuzumab-based adjuvant therapy. The benefit from neratinib appeared to be greater in patients with ER⁺/HER2⁺ tumors. We thus sought to discover mechanisms that may explain the benefit from extended adjuvant therapy with neratinib.Experimental Design: Mice with established ER⁺/HER2⁺ MDA-MB-361 tumors were treated with paclitaxel plus trastuzumab ± pertuzumab for 4 weeks, and then randomized to fulvestrant ± neratinib treatment. The benefit from neratinib was evaluated by performing gene expression analysis for 196 ER targets, ER transcriptional reporter assays, and cell-cycle analyses.

RESULTS

Mice receiving "extended adjuvant" therapy with fulvestrant/neratinib maintained a complete response, whereas those treated with fulvestrant relapsed rapidly. In three ER⁺/HER2⁺ cell lines (MDA-MB-361, BT-474, UACC-893) but not in ER⁺/HER2^- MCF7 cells, treatment with neratinib induced ER reporter transcriptional activity, whereas treatment with fulvestrant resulted in increased HER2 and EGFR phosphorylation, suggesting compensatory reciprocal crosstalk between the ER and ERBB RTK pathways. ER transcriptional reporter assays, gene expression, and immunoblot analyses showed that treatment with neratinib/fulvestrant, but not fulvestrant, potently inhibited growth and downregulated ER reporter activity, P-AKT, P-ERK, and cyclin D1 levels. Finally, similar to neratinib, genetic and pharmacologic inactivation of cyclin D1 enhanced fulvestrant action against ER⁺/HER2⁺ breast cancer cells.

CONCLUSIONS

These data suggest that ER blockade leads to reactivation of ERBB RTKs and thus extended ERBB blockade is necessary to achieve durable clinical outcomes in patients with ER⁺/HER2⁺ breast cancer.

The brain microenvironment mediates resistance in luminal breast cancer to PI3K inhibition through HER3 activation

Although targeted therapies are often effective systemically, they fail to adequately control brain metastases. In preclinical models of breast cancer that faithfully recapitulate the disparate clinical responses in these microenvironments, we observed that brain metastases evade phosphatidylinositide 3-kinase (PI3K) inhibition despite drug accumulation in the brain lesions. In comparison to extracranial disease, we observed increased HER3 expression and phosphorylation in brain lesions. HER3 blockade overcame the resistance of HER2-amplified and/or PIK3CA-mutant breast cancer brain metastases to PI3K inhibitors, resulting in marked tumor growth delay and improvement in mouse survival. These data provide a mechanistic basis for therapeutic resistance in the brain microenvironment and identify translatable treatment strategies for HER2-amplified and/or PIK3CA-mutant breast cancer brain metastases.

Comparison of anatomical tibial plateau angle versus observer measurement from lateral radiographs in dogs

This study was conducted to compare the anatomical tibial plateau angle (TPA) with that measured by observers from a lateral radiograph of the limb, the hypothesis being that there would not be any statistically significant differences between the observer measured TPA and the true anatomical TPA. Twelve pelvic limbs from skeletally mature greyhound cadavers, without any clinical or radiographic evidence of stifle pathology, were used in this study. The radiographs were taken of each limb in a lateral position with the primary beam centered over the tibial eminences and collimated to include the stifle and tarso-crural joints. For subsequent radiographs, Kirschner wires were inserted to enable identification of the tibial plateau. The TPA was then measured, by three observers, from the plain radiographs and by one observer from the marked radiographs. The mean observer TPA was 24.4° (range 17–30°) and the mean anatomical TPA was 23.8° (range 15–31°). The mean and median discrepancy between the anatomical TPA and the observer TPA was negative and very small (− 0.64° and 0°). The magnitude of the discrepancy between individual measurements made by the observers tended to overestimate small angles and underestimate the large ones, and this trend is statistically significant. These results suggest that the measurements made by observers accurately represent the anatomical slope of the tibial plateau. Therefore, observer TPA is suitable for the planning and assessment of TPLO procedures. However, as the anatomical TPA moves away from a median angle (23.25°) the magnitude of error in the measurement increases.

Abstract GS6-05: Gain-of-function kinase library screen identifies FGFR1 amplification as a mechanism of resistance to antiestrogens and CDK4/6 inhibitors in ER+ breast cancer

Background: CDK4/6 inhibitors have been approved in combination with endocrine therapy for treatment of ER+ metastatic breast cancer. The goal of this study was to discover mechanisms of resistance to ER antagonists alone and in combination with CDK4/6 inhibitors.

Results: To achieve this goal, we used lentiviral vectors to individually express 559 human kinase open reading frames (ORFs) in ER+ MCF7 human breast cancer cells treated with fulvestrant ± the CDK4/6 inhibitor ribociclib. In MCF7 cells treated with fulvestrant alone or with ribociclib, we identified 15 and 17 kinases associated with resistance, respectively. Ten of these kinases overlapped in both groups. In a secondary screen, MCF7 cells were stably transduced with V5-tagged lentiviruses expressing the positive 'hits' for treatment with fulvestrant/ribociclib. Five of 17 kinases (FGFR1, FRK, HCK, FGR, CRKL) were confirmed to induce resistance to fulvestrant/palbociclib and fulvestrant/ribociblib. Survey of TCGA for copy number alterations and/or expression of these 5 genes showed only FGFR1 to be amplified/overexpressed in ˜15% of ER+ breast cancers. Experiments in vitro showed that ER+/FGFR1-amplified (amp) MDA-134, CAMA-1 and HCC1500 human breast cancer cells and MCF7 cells stably transduced with FGFR1 were relatively resistant to estrogen deprivation, fulvestrant and fulvestrant/palbociclib compared to non-FGFR1 amp MCF7 cells. This resistance was abrogated by treatment with the FGFR tyrosine kinase inhibitor (TKI) lucitanib. Treatment with fulvestrant or palbociclib alone modestly delayed growth of ER+/FGFR1-amp breast cancer patient-derived xenografts (PDX) established in nude mice. However, addition of the FGFR TKI erdafitinib to fulvestrant/palbociclib resulted in marked PDX regression in all mice without associated toxicity and a complete cell cycle arrest measured by Ki67. Treatment of FGFR-amp cells with FGF-2 strongly induced CCND1 (cyclin D1) expression. Downregulation of CCND1 with CCND1 RNAi oligonucleotides restored sensitivity of FGFR1-amp cells to fulvestrant/palbociclib, thus phenocopying the effect of FGFR TKIs. Conversely, overexpression of CCND1 in MCF7 cells induced resistance to estrogen deprivation and to fulvestrant ± palbociclib. Finally, we examined next gen sequencing of cell free tumor DNA by Guardant360 in 34 patients before and after progression on CDK4/6 inhibitor. In 10/34 (29%) post-progression specimens, we detected alterations in the FGFR pathway: FGFR1 amplification (n=7), FGFR1 N546K (n=1), FGFR2 N549K (n=1), and FGFR2 V395D (n=1) activating mutations.

Conclusions: These data suggest aberrant FGFR signaling is a mechanism of resistance to anti-ER therapies ± CDK4/6 inhibitors. We posit overexpression of cyclin D1 induced by both FGFR signaling and ER transcription plays a role in drug resistance. Based on these findings we propose ER+/FGFR1 amplified breast cancers are endocrine resistant and should be candidates for treatment with combinations of ER and FGFR antagonists. Accordingly, we have initiated a phase Ib trial of fulvestrant, palbociclib and erdafitinib in patients with antiestrogen resistant ER+/HER2-negative breast cancer with FGFR1-4 amplification.

Citation Format: Formisano L, Lu Y, Jansen VM, Bauer JA, Hanker A, Gonzalez Ericsson P, Lee K-M, Nixon MJ, Guerrero-Zotano AL, Schwarz LJ, Sanders M, Sudhan D, Dugger TC, Cruz MR, Behdad A, Cristofanilli M, Bardia A, O'Shaughnessy J, Mayer IA, Arteaga CL. Gain-of-function kinase library screen identifies FGFR1 amplification as a mechanism of resistance to antiestrogens and CDK4/6 inhibitors in ER+ breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr GS6-05.

MHC-II expression to drive a unique pattern of adaptive resistance to antitumor immunity through receptor checkpoint engagement

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Background: Anti-PD-1 therapy is effective in many cancers, but tumor-intrinsic factors governing response and resistance are largely unknown. MHC-II (HLA-DR) expression on tumor cells can predict response to anti-PD-1. Thus, we sought to determine the molecular features of MHC-II+ tumors in the evolution of anti-PD-1 response. Methods: We performed RNA-seq on 58 anti-PD-1 treated melanoma and lung tumors, including a subset of matched specimens prior to treatment and at acquired resistance. We performed immunohistochemistry (IHC) for immunologic markers, including HLA-DR on tumor cells. In triple-negative breast cancers (TNBC; n = 103), we performed IHC and/or quantitative immunofluorescence (QIF) for LAG3, PD-L1, CD4, CD8, Fc-receptor-like 6 (FCRL6), and granzyme B (GZMB). QIF images were assessed by Automated Quantitative Analysis (AQUA). To determine the functional effect of MHC-II on tumor cells, we generated isogenic MHC-II+ mouse tumors and assessed immune responsiveness and efficacy of checkpoint inhibition. Results: We identified unique inflammatory signatures in HLA-DR+ tumors, correlating with enhanced pre-treatment CD4+ and CD8+ tumor-infiltrating lymphocytes (TILs) and response to anti-PD-1. LAG3+ and FCRL6+ TILs were enriched in HLA-DR+ tumors. LAG3 and FCRL6, known inhibitory receptors which bind MHC-II, were elevated at anti-PD-1 resistance. Similarly, in > 100 TNBCs, HLA-DR+ tumor cells associated with increased CD4+ and CD8+ TILs and enhanced LAG3+ and FCRL6+ TILs. Further, presence of MHC-II-suppressing (LAG3+/FCRL6+) TILs associated with decreased GZMB+ CD8+ T cells, suggesting suppressed cytotoxicity. In mice, enforced expression of MHC-II on tumor cells enhanced CD4-enhanced anti-tumor immunity but was thwarted by LAG3+ TIL recruitment. Combined anti-LAG3 and anti-PD-1 therapy was selectively effective in MHC-II+ tumors. Conclusions: MHC-II+ tumors are immunologically active and may circumvent anti-tumor immunity by targeting MHC-II antigen presentation via recruitment of MHC-II-suppressing TILs. MHC-II expression may be useful to stratify patients to anti-PD-1/anti-LAG3 and eventually, anti-PD-1/anti-FCRL6 combinations.

Assessing Tumor-Infiltrating Lymphocytes in Solid Tumors: A Practical Review for Pathologists and Proposal for a Standardized Method from the International Immuno-Oncology Biomarkers Working Group: Part 2: TILs in Melanoma, Gastrointestinal Tract Carcinomas, Non-Small Cell Lung Carcinoma and Mesothelioma, Endometrial and Ovarian Carcinomas, Squamous Cell Carcinoma of the Head and Neck, Genitourinary Carcinomas, and Primary Brain Tumors

Assessment of the immune response to tumors is growing in importance as the prognostic implications of this response are increasingly recognized, and as immunotherapies are evaluated and implemented in different tumor types. However, many different approaches can be used to assess and describe the immune response, which limits efforts at implementation as a routine clinical biomarker. In part 1 of this review, we have proposed a standardized methodology to assess tumor-infiltrating lymphocytes (TILs) in solid tumors, based on the International Immuno-Oncology Biomarkers Working Group guidelines for invasive breast carcinoma. In part 2 of this review, we discuss the available evidence for the prognostic and predictive value of TILs in common solid tumors, including carcinomas of the lung, gastrointestinal tract, genitourinary system, gynecologic system, and head and neck, as well as primary brain tumors, mesothelioma and melanoma. The particularities and different emphases in TIL assessment in different tumor types are discussed. The standardized methodology we propose can be adapted to different tumor types and may be used as a standard against which other approaches can be compared. Standardization of TIL assessment will help clinicians, researchers and pathologists to conclusively evaluate the utility of this simple biomarker in the current era of immunotherapy.

Assessing Tumor-infiltrating Lymphocytes in Solid Tumors: A Practical Review for Pathologists and Proposal for a Standardized Method From the International Immunooncology Biomarkers Working Group: Part 1: Assessing the Host Immune Response, TILs in Invasive Breast Carcinoma and Ductal Carcinoma In Situ, Metastatic Tumor Deposits and Areas for Further Research

Assessment of tumor-infiltrating lymphocytes (TILs) in histopathologic specimens can provide important prognostic information in diverse solid tumor types, and may also be of value in predicting response to treatments. However, implementation as a routine clinical biomarker has not yet been achieved. As successful use of immune checkpoint inhibitors and other forms of immunotherapy become a clinical reality, the need for widely applicable, accessible, and reliable immunooncology biomarkers is clear. In part 1 of this review we briefly discuss the host immune response to tumors and different approaches to TIL assessment. We propose a standardized methodology to assess TILs in solid tumors on hematoxylin and eosin sections, in both primary and metastatic settings, based on the International Immuno-Oncology Biomarker Working Group guidelines for TIL assessment in invasive breast carcinoma. A review of the literature regarding the value of TIL assessment in different solid tumor types follows in part 2. The method we propose is reproducible, affordable, easily applied, and has demonstrated prognostic and predictive significance in invasive breast carcinoma. This standardized methodology may be used as a reference against which other methods are compared, and should be evaluated for clinical validity and utility. Standardization of TIL assessment will help to improve consistency and reproducibility in this field, enrich both the quality and quantity of comparable evidence, and help to thoroughly evaluate the utility of TILs assessment in this era of immunotherapy.

Association of FGFR1 with ERα Maintains Ligand-Independent ER Transcription and Mediates Resistance to Estrogen Deprivation in ER+ Breast Cancer

Purpose:FGFR1 amplification occurs in approximately 15% of estrogen receptor-positive (ER⁺) human breast cancers. We investigated mechanisms by which FGFR1 amplification confers antiestrogen resistance to ER⁺ breast cancer.Experimental Design: ER⁺ tumors from patients treated with letrozole before surgery were subjected to Ki67 IHC, FGFR1 FISH, and RNA sequencing (RNA-seq). ER⁺/FGFR1-amplified breast cancer cells, and patient-derived xenografts (PDX) were treated with FGFR1 siRNA or the FGFR tyrosine kinase inhibitor lucitanib. Endpoints were cell/xenograft growth, FGFR1/ERα association by coimmunoprecipitation and proximity ligation, ER genomic activity by ChIP sequencing, and gene expression by RT-PCR.Results: ER⁺/FGFR1-amplified tumors in patients treated with letrozole maintained cell proliferation (Ki67). Estrogen deprivation increased total and nuclear FGFR1 and FGF ligands expression in ER⁺/FGFR1-amplified primary tumors and breast cancer cells. In estrogen-free conditions, FGFR1 associated with ERα in tumor cell nuclei and regulated the transcription of ER-dependent genes. This association was inhibited by a kinase-dead FGFR1 mutant and by treatment with lucitanib. ChIP-seq analysis of estrogen-deprived ER⁺/FGFR1-amplified cells showed binding of FGFR1 and ERα to DNA. Treatment with fulvestrant and/or lucitanib reduced FGFR1 and ERα binding to DNA. RNA-seq data from FGFR1-amplified patients' tumors treated with letrozole showed enrichment of estrogen response and E2F target genes. Finally, growth of ER⁺/FGFR1-amplified cells and PDXs was more potently inhibited by fulvestrant and lucitanib combined than each drug alone.Conclusions: These data suggest the ERα pathway remains active in estrogen-deprived ER⁺/FGFR1-amplified breast cancers. Therefore, these tumors are endocrine resistant and should be candidates for treatment with combinations of ER and FGFR antagonists. Clin Cancer Res; 23(20); 6138-50. ©2017 AACR.

Abstract 5008: The brain microenvironment mediates resistance in luminal breast cancer to PI3K inhibition through HER3 activation

Brain metastases represent a devastating progression of luminal breast cancer. While targeted therapies are often effective systemically, they fail to adequately control brain metastases. In preclinical models that faithfully recapitulate the disparate clinical responses in these microenvironments, we observed that brain metastases evade PI3K inhibition despite efficient drug delivery. In comparison to extracranial disease, there is increased HER3 expression and phosphorylation in the brain lesions. HER3 blockade overcomes the resistance of both HER2-amplified and/or PIK3CA-mutant breast cancer brain metastases to PI3K inhibitors, leading to striking tumor growth delay and significant improvement of mouse survival. Collectively, these data provide a mechanistic basis underlying therapeutic resistance in the brain microenvironment and identify rapidly translatable treatment strategiesfor HER2-amplified and/or PIK3CA-mutant breast cancer brain metastases.

Citation Format: Gino B. Ferraro, David P. Kodack, Vasileios Askoxylakis, Qing Sheng, Mark Badeaux, Shom Goel, Xiaolong Qi, Ram Shankaraiah, Alexander Z. Cao, Rakesh R. Ramjiawan, Divya Bezwada, Bhushankumar Patel, Youngchul Song, Carlotta Costa, Kamila Naxerova, Christina Wong, Jonas Kloepper, Rita Das, Angela Tam, Jantima Tanboon, Dan G. Duda, Ryan C. Miller, Marni B. Siegel, Carey K. Anders, Melinda Sanders, Valeria M. Estrada, Robert Schlegel, Carlos L. Arteaga, Elena Brachtel, Alan Huang, Dai Fukumura, Jeffrey A. Engelman, Rakesh K. Jain. The brain microenvironment mediates resistance in luminal breast cancer to PI3K inhibition through HER3 activation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5008. doi:10.1158/1538-7445.AM2017-5008

Abstract 3890: Mitochondrial MCL1 maintains triple negative breast cancer stem cells and contributes to chemotherapy resistance

Cytotoxic chemotherapy is the standard of care for patients with triple negative breast cancer (TNBC). Most patients with advanced TNBC progress after chemotherapy and die from metastatic disease. MCL1 is an anti-apoptotic Bcl-2 family member known to sequester and inactivate pro-apoptotic Bcl-2 family proteins and, thus, contribute to chemotherapy resistance. We previously reported that ~45% of residual TNBCs that remain in the breast after neoadjuvant chemotherapy harbor MCL1 amplification, suggesting a causal role for MCL1 in drug resistance. A recent report (Goodwin et al. 2015) suggested that siRNA-mediated ablation of MCL1 does not induce apoptosis in claudin-low TNBC cells with a cancer stem cell (CSC) gene expression signature. CSCs comprise a rare population of cells with tumor-initiating properties and refractoriness to chemotherapy. In this study, we showed that MCL1 expression is elevated in claudin-low TNBC SUM159PT and MDA436 CSCs as measured by ALDH+ by flow cytometry and ability to form mammospheres. RNA interference of MCL1 in SUM159PT cells reduced CSCs and attenuated tumor formation in vivo. Mitochondrial oxidative phosphorylation (mtOXPHOS) plays a crucial role in maintenance of CSCs. MCL1 has been shown to localize in the mitochondrial matrix and contribute to mitochondrial respiration. Thus, we hypothesized that MCL1 contributes to enrichment of TNBC CSCs and chemotherapy resistance via mitochondrial regulation. Stable transfection and overexpression of MCL1 in MDA468 cells increased oxygen consumption ratio, mitochondrial membrane potential, and production of reactive oxygen species (ROS), all features of activated mtOXPHOS. Conversely, RNAi-mediated ablation of MCL1 in SUM159PT and MDA436 cells repressed these markers of activated mtOXPHOS. A mutant of MCL1 lacking its mitochondrial target sequences (MTS) was unable to localize in mitochondria and, when transfected into MDA468 cells, reduced the CD44high/CD24low fraction and mammosphere formation. We next tested VU0659158, a BH3 mimetic in development at Vanderbilt that disrupts MCL1 interactions with BH3 domain-containing proteins, such as BID, BIM, NOXA and PUMA. Treatment of SUM159PT cells with VU0659158 increased caspase activity but did not attenuate mammosphere formation. Analysis of mRNA expression in TCGA revealed that genes induced by mtOXPHOS involved in the hypoxia pathway are significantly up-regulated in MCL1 amplified breast cancers. Finally, pharmacological inhibition of HIF-1α, a key regulator of hypoxia, with digoxin decreased CSCs and attenuated tumor formation in vivo. These data suggest that 1) MCL1 confers resistance to chemotherapy by expanding CSCs via mtOXPHOS independent of its BH3 domain-mediated, anti-apoptotic function, and 2) targeting mitochondrial respiration and the hypoxia pathway may delay or reverse chemotherapy resistance in MCL1 amplified TNBC.

Citation Format: Kyung-min Lee, Jennifer Giltnane, Justin Balko, Luis Schwarz, Angel Guerrero, Katie Hutchinson, Mellissa Hicks, Violeta Sanchez, Melinda Sanders, Taekyu Lee, Edward Olejniczak, Stephen Fesik, Carlos Arteaga. Mitochondrial MCL1 maintains triple negative breast cancer stem cells and contributes to chemotherapy resistance [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3890. doi:10.1158/1538-7445.AM2017-3890

Modulation of Aneuploidy in Leishmania donovani during Adaptation to Different In Vitro and In Vivo Environments and Its Impact on Gene Expression

Aneuploidy is usually deleterious in multicellular organisms but appears to be tolerated and potentially beneficial in unicellular organisms, including pathogens. Leishmania, a major protozoan parasite, is emerging as a new model for aneuploidy, since in vitro-cultivated strains are highly aneuploid, with interstrain diversity and intrastrain mosaicism. The alternation of two life stages in different environments (extracellular promastigotes and intracellular amastigotes) offers a unique opportunity to study the impact of environment on aneuploidy and gene expression. We sequenced the whole genomes and transcriptomes of Leishmania donovani strains throughout their adaptation to in vivo conditions mimicking natural vertebrate and invertebrate host environments. The nucleotide sequences were almost unchanged within a strain, in contrast to highly variable aneuploidy. Although high in promastigotes in vitro, aneuploidy dropped significantly in hamster amastigotes, in a progressive and strain-specific manner, accompanied by the emergence of new polysomies. After a passage through a sand fly, smaller yet consistent karyotype changes were detected. Changes in chromosome copy numbers were correlated with the corresponding transcript levels, but additional aneuploidy-independent regulation of gene expression was observed. This affected stage-specific gene expression, downregulation of the entire chromosome 31, and upregulation of gene arrays on chromosomes 5 and 8. Aneuploidy changes in Leishmania are probably adaptive and exploited to modulate the dosage and expression of specific genes; they are well tolerated, but additional mechanisms may exist to regulate the transcript levels of other genes located on aneuploid chromosomes. Our model should allow studies of the impact of aneuploidy on molecular adaptations and cellular fitness.IMPORTANCE Aneuploidy is usually detrimental in multicellular organisms, but in several microorganisms, it can be tolerated and even beneficial. Leishmania-a protozoan parasite that kills more than 30,000 people each year-is emerging as a new model for aneuploidy studies, as unexpectedly high levels of aneuploidy are found in clinical isolates. Leishmania lacks classical regulation of transcription at initiation through promoters, so aneuploidy could represent a major adaptive strategy of this parasite to modulate gene dosage in response to stressful environments. For the first time, we document the dynamics of aneuploidy throughout the life cycle of the parasite, in vitro and in vivo We show its adaptive impact on transcription and its interaction with regulation. Besides offering a new model for aneuploidy studies, we show that further genomic studies should be done directly in clinical samples without parasite isolation and that adequate methods should be developed for this.

The molecular basis of breast cancer pathological phenotypes

The histopathological evaluation of morphological features in breast tumours provides prognostic information to guide therapy. Adjunct molecular analyses provide further diagnostic, prognostic and predictive information. However, there is limited knowledge of the molecular basis of morphological phenotypes in invasive breast cancer. This study integrated genomic, transcriptomic and protein data to provide a comprehensive molecular profiling of morphological features in breast cancer. Fifteen pathologists assessed 850 invasive breast cancer cases from The Cancer Genome Atlas (TCGA). Morphological features were significantly associated with genomic alteration, DNA methylation subtype, PAM50 and microRNA subtypes, proliferation scores, gene expression and/or reverse-phase protein assay subtype. Marked nuclear pleomorphism, necrosis, inflammation and a high mitotic count were associated with the basal-like subtype, and had a similar molecular basis. Omics-based signatures were constructed to predict morphological features. The association of morphology transcriptome signatures with overall survival in oestrogen receptor (ER)-positive and ER-negative breast cancer was first assessed by use of the Molecular Taxonomy of Breast Cancer International Consortium (METABRIC) dataset; signatures that remained prognostic in the METABRIC multivariate analysis were further evaluated in five additional datasets. The transcriptomic signature of poorly differentiated epithelial tubules was prognostic in ER-positive breast cancer. No signature was prognostic in ER-negative breast cancer. This study provided new insights into the molecular basis of breast cancer morphological phenotypes. The integration of morphological with molecular data has the potential to refine breast cancer classification, predict response to therapy, enhance our understanding of breast cancer biology, and improve clinical management. This work is publicly accessible at www.dx.ai/tcga_breast. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

PI3K Inhibition Reduces Mammary Tumor Growth and Facilitates Antitumor Immunity and Anti-PD1 Responses

Purpose: Metastatic breast cancers continue to elude current therapeutic strategies, including those utilizing PI3K inhibitors. Given the prominent role of PI3Kα,β in tumor growth and PI3Kγ,δ in immune cell function, we sought to determine whether PI3K inhibition altered antitumor immunity.Experimental Design: The effect of PI3K inhibition on tumor growth, metastasis, and antitumor immune response was characterized in mouse models utilizing orthotopic implants of 4T1 or PyMT mammary tumors into syngeneic or PI3Kγ-null mice, and patient-derived breast cancer xenografts in humanized mice. Tumor-infiltrating leukocytes were characterized by IHC and FACS analysis in BKM120 (30 mg/kg, every day) or vehicle-treated mice and PI3Kγ^null versus PI3Kγ^WT mice. On the basis of the finding that PI3K inhibition resulted in a more inflammatory tumor leukocyte infiltrate, the therapeutic efficacy of BKM120 (30 mg/kg, every day) and anti-PD1 (100 μg, twice weekly) was evaluated in PyMT tumor-bearing mice.Results: Our findings show that PI3K activity facilitates tumor growth and surprisingly restrains tumor immune surveillance. These activities could be partially suppressed by BKM120 or by genetic deletion of PI3Kγ in the host. The antitumor effect of PI3Kγ loss in host, but not tumor, was partially reversed by CD8⁺ T-cell depletion. Treatment with therapeutic doses of both BKM120 and antibody to PD-1 resulted in consistent inhibition of tumor growth compared with either agent alone.Conclusions: PI3K inhibition slows tumor growth, enhances antitumor immunity, and heightens susceptibility to immune checkpoint inhibitors. We propose that combining PI3K inhibition with anti-PD1 may be a viable therapeutic approach for triple-negative breast cancer. Clin Cancer Res; 23(13); 3371-84. ©2016 AACR.

Classification and analysis of human ovarian tissue using full field optical coherence tomography

In this study, a full field optical coherence tomography (FFOCT) system was used to analyze and classify normal and malignant human ovarian tissue. 14 ovarian tissue samples (7 normal, 7 malignant) were imaged with the FFOCT system and five features were extracted by analyzing the normalized image histogram from 56 FFOCT images, based on the differences in the morphology of the normal and malignant tissue samples. A generalized linear model (GLM) classifier was trained using 36 images, and sensitivity of 95.3% and specificity of 91.1% was obtained. 20 images were used to test the model, and a sensitivity of 91.6% and specificity of 87.7% was obtained.

Characterizing optical properties and spatial heterogeneity of human ovarian tissue using spatial frequency domain imaging

A spatial frequency domain imaging (SFDI) system was developed for characterizing ex vivo human ovarian tissue using wide-field absorption and scattering properties and their spatial heterogeneities. Based on the observed differences between absorption and scattering images of different ovarian tissue groups, six parameters were quantitatively extracted. These are the mean absorption and scattering, spatial heterogeneities of both absorption and scattering maps measured by a standard deviation, and a fitting error of a Gaussian model fitted to normalized mean Radon transform of the absorption and scattering maps. A logistic regression model was used for classification of malignant and normal ovarian tissues. A sensitivity of 95%, specificity of 100%, and area under the curve of 0.98 were obtained using six parameters extracted from the SFDI images. The preliminary results demonstrate the diagnostic potential of the SFDI method for quantitative characterization of wide-field optical properties and the spatial distribution heterogeneity of human ovarian tissue. SFDI could be an extremely robust and valuable tool for evaluation of the ovary and detection of neoplastic changes of ovarian cancer.