Abstract GS5-05: Resistance to neoadjuvant chemotherapy in triple negative breast cancer mediated by a reversible drug-tolerant state

Approximately 50% of patients with localized triple negative breast cancer (TNBC) have substantial residual cancer burden following treatment with neoadjuvant chemotherapy (NACT), resulting in distant metastasis and death for most of these patients. While genomic and phenotypic intra-tumor heterogeneity are pervasive features of TNBCs at the time of diagnosis, the functional contributions of heterogeneous tumor cell populations to chemoresistance have not been elucidated.

To investigate tumor evolution accompanying NACT, we employed orthotopic patient-derived xenograft (PDX) models of treatment-naïve TNBC, which retain intra-tumor heterogeneity characteristic of human TNBC. We discovered that some PDX models initially exhibited partial sensitivity to standard front-line NACT (Adriamycin plus Cytoxan, AC). Following AC, residual tumors were resistant to chemotherapy but repopulated tumors with chemo-sensitive cells if left untreated, indicating that tumor cells possessed inherent plasticity. To identify the tumor cell subpopulation(s) conferring chemoresistance, we conducted barcode-mediated clonal tracking in three independent PDX models by introducing a high-complexity pooled lentiviral barcode library into PDX tumor cells which were then orthotopically engrafted into recipient mice. Strikingly, residual tumors maintained the same heterogeneous clonal architecture as naïve tumors. Concordantly, whole-exome sequencing revealed conservation of genomic subclonal architecture throughout treatment. These results were corroborated by genomic sequencing of serial biopsies pre- and post-AC obtained directly from TNBC patients enrolled on an ongoing clinical trial at MD Anderson (ARTEMIS; NCT02276443). Together, these studies revealed that genomically distinct pre-treatment subclones were equally capable of surviving AC to reconstitute tumors after treatment.

To identify functional addictions of residual tumor cells, we conducted histologic and transcriptomic profiling. Residual tumors following AC-treatment exhibited extensive fibrotic desmoplasia and tumor cell pleomorphism in both PDX models and in serial biopsies obtained from TNBC patients enrolled on the ARTEMIS trial. Strikingly, these AC-induced features were reverted upon regrowth of residual tumors in PDXs and in patients' tumors. Similarly, residual tumors exhibited unique transcriptomic features, many of which are also de-regulated in cohorts of human TNBCs undergoing chemotherapy treatment. These features were nearly completely reverted after tumors regrew, suggesting that the residual tumor state may be a unique and transient therapeutic window. Gene set enrichment analyses revealed that residual tumors had increased activation of oxidative phosphorylation and decreased glycolytic signaling. Pharmacologic targeting of oxidative phosphorylation with a small-molecule inhibitor of mitochondrial electron transport chain complex I (IACS-010759) significantly delayed the regrowth of AC-treated residual tumors in three independent PDX models. Collectively, these studies reveal that a reversible phenotypic state can confer chemoresistance in the absence of genomic selection and that the residual tumor state is a novel therapeutic window for chemo-refractory TNBC.

Citation Format: Echeverria GV, Ge Z, Seth S, Jeter-Jones SL, Zhang X, Zhou X, Cai S, Tu Y, McCoy A, Peoples M, Lau R, Shao J, Sun Y, Bristow C, Carugo A, Ma X, Harris A, Wu Y, Moulder S, Symmans WF, Marszalek JR, Heffernan TP, Chang JT, Piwnica-Worms H. Resistance to neoadjuvant chemotherapy in triple negative breast cancer mediated by a reversible drug-tolerant state [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr GS5-05.

Abstract P3-07-03: Withdrawn

This abstract was withdrawn by the authors.

Citation Format: Rinkenbaugh AL, Sinha VC, Zhang X, Shao J, Piwnica-Worms H. Withdrawn [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-07-03.

Test of the hadronic interaction models SIBYLL2.3, EPOS-LHC and QGSJETII- 04 with Tibet EAS core data

A hybrid experiment has been started by the ASγ experiment at Yangbajing (4300m a.s.l.) in Tibet since May 2009, that consists of a high-energy air-shower-core array (YAC-I) and a high-density air-shower array (Tibet-III). In this paper, we report our results to check the hadronic interaction models SIBYLL2.3, SIBYLL2.1, EPOS-LHC and QGSJETII-04 in the multi-tens TeV energy region using YAC-I+Tibet-III experimental data from May 2009 through January 2010. The effective live time is calculated as 106.05 days. The results show that the description of transverse momentum, inelastic cross-section and inelasticity for the 4 hadronic interaction models is consistent with YAC-I experimental data within 15% systematic errors range in the forward region below 100 TeV. Among them, the EPOS-LHC model is the best hadronic interaction model. Furthermore, we find that the H4a composition model is the best one below the 100 TeV energy region.

On the Solar Cycle Variation of the Solar Diurnal Anisotropy of Multi-TeV Cosmic-ray Intensity Observed with the Tibet Air Shower Array

We analyze the temporal variation of the solar diurnal anisotropy of the multi-TeV cosmic-ray intensity observed with the Tibet air shower array from 2000 to 2009, covering the maximum and minimum of the 23rd solar cycle. We comfirm that a remarkable additional anisotropy component is superposed on the Compton-Getting anisotropy at 4.0 TeV, while its amplitude decreases at higher energy regions. In constrast to the additional anisotropy reported by the Matsushiro experiment at 0.6 TeV, we find the residual component measured by Tibet at multi-TeV energies is consistent with being stable, with a fairly constant amplitude of 0.041% ± 0.003% and a phase at around 07.17 ± 00.16 local solar time at 4.0 TeV. This suggests the additional anisotropy observed by the Tibet experiment could result from mechanisms unrelated to solar activities.

Differentiation of Transformed Bipolar Disorder From Unipolar Depression by Resting-State Functional Connectivity Within Reward Circuit

Previous studies have found that neural functional abnormalities detected by functional magnetic resonance imaging (fMRI) in brain regions implicated in reward processing during reward tasks show promise to distinguish bipolar from unipolar depression (UD), but little is known regarding resting-state functional connectivity (rsFC) within the reward circuit. In this study, we investigated neurobiomarkers for early recognition of bipolar disorder (BD) by retrospectively comparing rsFC within the reward circuit between UD and depressed BD. Sixty-six depressed patients were enrolled, none of whom had ever experienced any manic/hypomanic episodes before baseline. Simultaneously, 40 matched healthy controls (HC) were also recruited. Neuroimaging data of each participant were obtained from resting-state fMRI scans. Some patients began to manifest bipolar disorder (tBD) during the follow-up period. All patients were retrospectively divided into two groups (33 tBD and 33 UD) according to the presence or absence of mania/hypomania in the follow-up. rsFC between key regions of the reward circuit was calculated and compared among groups. Results showed decreased rsFC between the left ventral tegmental area (VTA) and left ventral striatum (VS) in the tBD group compared with the UD group, which showed good accuracy in predicting diagnosis (tBD vs. UD) according to receiver operating characteristic (ROC) analysis. No significant different rsFC was found within the reward circuit between any patient group and HC. Our preliminary findings indicated that bipolar disorder, in early depressive stages before onset of mania/hypomania attacks, already differs from UD in the reward circuit of VTA-VS functional synchronicity at the resting state.

TPH-2 Gene Polymorphism in Major Depressive Disorder Patients With Early-Wakening Symptom

Background: Sleep disturbances, such as early wakening, are frequently observed in patients with major depressive disorder (MDD). The suprachiasmatic nuclei (SCN), which controls circadian rhythm, is innervated by the raphe nucleus, a region where Tryptophan hydroxylase-2 (TPH-2) gene is primarily expressed. Although TPH-2 is often implicated in the pathophysiology of depression, few studies have applied a genetic and imaging technique to investigate the mechanism of early wakening symptom in MDD. We hypothesized that TPH-2 variants could influence the function of SCN in MDD patients with early wakening symptom. Methods: One hundred and eighty five MDD patients (62 patients without early wakening and 123 patients with early wakening) and 64 healthy controls participated in this study. Blood samples were collected and genotyping of rs4290270, rs4570625, rs11178998, rs7305115, rs41317118, and rs17110747 were performed by next-generation sequencing (NGS) technology. Logistic regression model was employed for genetic data analysis using the PLINK software. Based on the allele type, rs4290270, which was significant in the early wakening MDD group, participants were categorized into two groups (A allele and T carrier). All patients underwent whole brain resting-state functional magnetic resonance imaging (rs-fMRI) scanning and a voxel-wise functional connectivity comparison was performed between the groups. Results: rs4290270 was significantly linked to MDD patients who exhibited early wakening symptom. The functional connectivities of the right SCN with the right fusiform gyrus and right middle frontal gyrus were increased in the T carrier group compared to the A allele group. In addition, the functional connectivities of the left SCN with the right lingual gyrus and left calcarine sulcus were decreased in the T carrier group compared to the A allele group. Conclusion: These findings suggested that the TPH-2 gene variant, rs4290270, affected the circadian regulating function of SCN. The altered functional connectivities, observed between the SCN and right fusiform gyrus, right middle frontal gyrus, the right lingual gyrus and left calcarine sulcus, could highlight the neural mechanism by which SCN induces sleep-related circadian disruption in T carrier MDD patients. Hence, rs4290270 could potentially serve as a reliable biomarker to identify MDD patients with early wakening symptom.

A Novel Thermoresponsive Gel as a Potential Delivery System for Lipoxin

The objective of this study was to evaluate a novel thermoresponsive polyisocyanopeptide (PIC)–based hydrogel as an injectable carrier for local drug delivery for periodontal applications. Three formulations of PIC gels, 0.2%, 0.5%, and 1% w/w, were prepared. As controls, commercially available poloxamer 407 (P407) gels of 20% and 26% w/w were used. Lipoxin A₄ (LXA₄), a proresolving drug, was suspended into the gel solutions. The systems were evaluated regarding dynamic mechanical properties, injectability and stability, release and bioactivity of LXA₄, and cytocompatibility. Results showed that the gelation temperatures of PIC and P407 gels were around 13°C to 23°C. PIC gels were less viscous and mechanically weaker than P407 gels due to the low polymer concentrations. However, PIC gels kept gel integrity for at least 2 wk when incubated with phosphate-buffered saline, whereas P407 gels were disintegrated totally within 1 wk. LXA₄ was chemically stable in both neutral and alkaline medium for over 1 mo. The release of LXA₄ from either 1% PIC or 26% P407 gels depicted an initial burst release followed by a sustained release for around 4 d. The extent of burst release was negatively correlated to the polymer concentration. LXA₄ remained bioactive after release from PIC gels. No cytotoxicity was observed for 1% PIC gel. However, 26% P407 inhibited periodontal ligament cell and gingival epithelial cell growth. In conclusion, the thermoresponsive PIC gel is a potential candidate for periodontal drug delivery.

[Simultaneous determination of trichloroethylene and trichloroethanol in blood by liquid-liquid extraction-gas chromatography]

Objective: To establish a method for determing the trichloroethylene(TCE)and trichloroethanol(TCOH)in blood samples by liquid-liquid extraction-gas chromatography with electron capture detector. Methods: With this method,ether was used as extraction solvent and trichloromethane was used as an internal standard. The whole blood sample was extracted with ether, and dehydrated by anhydrous sodium sulfate. Then the analytes were separated on HP-5 capillary column(30m×0.32mm×0.15μm)and detected byECD.The retention time was for qualitative analysis and the internal standard was for quantitation. Results: The standard curves of TCE and TCOH showed significant linearity between 95.5μg/L-7640.0μg/L(r=0.9997)and 19.0μg/L-1520.0μg/L(r=0.9992). The average recovery was 95.5%-103.6%.The intra-day and inter-day precisions(RSD)were 2.5%-6.8%(n=6)and 1.6%-4.3%(n=6) respectively. The detect limit of TCE and TCOH were 2.10 μg/L and 0.56μg/L(S/N=3)respectively.The blood can be kept 7 days at-20℃ refrigerator without significantly loss. Conclusion: This method is proved to be simple,practical and highly sensitive. It can satisfy the request for the determination of blood samples of humans exposed to TCE.

Modified Model of Whole Ovary Transplantation in Rats

OBJECTIVE

A rat model of right whole ovary transplantation is difficult to establish because of an unfit location or absence of the right ovarian artery. The purpose of this study is to develop a rat model of left whole ovary transplantation.

METHODS

Two methods of whole ovary transplantation were performed. In Group A (n = 40), the rats underwent right whole ovary grafting via conventional orthotopic allotransplant, with donor abdominal aorta and inferior vena cava end-to-side anastomoses to the recipient abdominal aorta and inferior vena cava. In Group B (n = 40), the rats underwent left whole ovary graft via orthotopic allotransplant, with donor abdominal aorta and left renal vein end-to-side anastomoses to the recipient abdominal aorta and inferior vena cava. Bilateral native ovariectomy in the recipient was performed immediately in both groups. The operative times, recipient survival rates, and transplanted ovarian function were measured.

RESULTS

There was no significant difference in the success rates of transplant between the 2 groups, with 92.5% and 90% success, respectively. All the living recipients recovered ovarian function. However, the operative time for the donor, the vein anastomosis time, and the cold ischemia time decreased significantly in Group B (P < .05).

CONCLUSION

The modified method of left whole ovary transplantation is reliable and easy to perform, which could significantly shorten the times of graft harvest and cold ischemia. The method is a good supplement and improvement of the conventional model of rat whole ovary transplantation.

THE CORRELATION BETWEEN NECK CIRCUMFERENCE AND UMBILICAL ARTERY BLOOD FLOW IN PHYSIOLOGIC PREGNANCIES

Objective

To study the correlation between neck circumference(NC) and umbilical artery blood flow in physiologic pregnancies.

Methods

One hundred and one healthy pregnant woman in the third trimester were enrolled. Anthropometric measurements and ultrasonic testing were done.

Results

The women with NC ≥34.7cm had a more elevated umbilical artery pulsatility index(PI) and systolic/diastolic ratio (S/D) than the women with NC <34.7cm (P<0.01). NC were positively correlated with PI(r=0.224,P=0.024) and S/D ratio(r=0.415,P=0.0001). In multivariate analysis, NC was independently associated with PI (β=0.026, P=0.016) and S/D ratio (β=0.132, P=0.0001).

Conclusions

Obesity has an adverse impact on feto-placetal vessels, and NC was superior to body mass index.

Abstract GS6-06: Identifying metastatic drivers in patient-derived xenograft models of triple negative breast cancer

Metastases are responsible for the vast majority of deaths due to breast cancer. Triple negative breast cancer (TNBC) is an aggressive subtype of breast cancer characterized by high rates of metastasis and poor prognosis. We are employing patient derived xenograft (PDX) models of TNBC to identify drivers of metastasis. Tumor samples are obtained from the breast tumors of patients with TNBC and engrafted immediately into the humanized mammary fat pads of immune compromised mice. Lentiviral transduction was employed to express bioluminescent and fluorescent markers in two independent PDX models of TNBC. Using these models, we demonstrated that human breast tumors are capable of completing all stages of the metastatic cascade in mice, and metastatic lesions are observed in organs normally found in patients with metastatic breast cancer including lung, liver, bone, brain, and lymph nodes. Dynamic and reversible epithelial to mesenchymal transition (EMT) was observed as tumors metastasized to lung and were re-passaged to recipient mouse mammary glands. Lung metastases were isolated using bioluminescence imaging and lung metastasis gene expression signatures were generated. Metastasis signatures from two independent PDX models were compared to identify genes that were commonly de-regulated in lung metastases relative to corresponding mammary tumors. Comprehensive gain-of-function screens were then conducted in vivo to identify functional drivers of TNBC metastasis. Carcinoembryonic antigen-related cell adhesion molecule 5 (CEACAM5) was identified as a metastatic driver in this screen. CEACAM5 mRNA and protein levels were elevated in lung metastases relative to corresponding mammary gland tumors in mice. In addition, we demonstrated that CEACAM5 expression was upregulated in the lung metastases of breast cancer patients, and its expression inversely correlated with patient survival. Our data indicate that the metastatic function of CEACAM5 is to promote growth of breast tumors in the lung by inducing MET (mesenchymal to epithelial transition).

Citation Format: Powell E, Shao J, Picon HM, Ge Z, Echeverria GV, Peoples M, Bristow C, Cai S, Tu Y, McCoy AM, Piwnica-Worms D, Draetta G, Edwards JR, Moulder SL, Symmans WF, Heffernan TP, Liang H, Piwnica-Worms H. Identifying metastatic drivers in patient-derived xenograft models of triple negative 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 GS6-06.

Abstract PD8-03: ESR1 gene fusions drive endocrine therapy resistance and metastasis in breast cancer

Background. Dysregulation of the estrogen receptor gene (ESR1) is an established mechanism of inducing endocrine therapy resistance. We previously discovered a chromosomal translocation event generating an estrogen receptor gene fused in-frame to C-terminal sequences of YAP1 (ESR1-YAP1) that contributed to endocrine therapy resistance in estrogen receptor positive (ER+) breast cancer models. This study compares functional, transcriptional, and pharmacological properties of additional ESR1 gene fusion events of both early stage (ESR1-NOP2) late stage (ESR1-YAP1 and ESR1-PCDH11x) breast cancers to gain a better understanding of therapeutic resistance and metastasis. Understanding the role of ESR1 fusions in inducing metastasis is critical, since the primary cause of death in breast cancer patients is through metastasis to distant sites.

Methods. RNA-seq screens identified ESR1 fusions from early and late stage, endocrine therapy resistant breast tumor samples. Functional experiments were conducted using ER+ breast cancer cell lines, xenograft, and PDX models to test the ability of ESR1 fusions to induce therapeutic resistance and metastasis. ChIP-seq and RNA-seq were performed to examine transcriptional properties and differential gene expression induced by the fusions which directed subsequent pharmacological experiments with a CDK4/6 inhibitor.

Results. ESR1-YAP1 and ESR1-PCDH11x promoted estrogen-independent and fulvestrant-resistant growth in vitro and induced greater tumor growth and increased metastatic capacity to the lungs of xenografted mice. In contrast, the ESR1-NOP2 fusion was sensitive to low estrogen conditions in vitro, and did not promote tumor growth. RNA-seq profiling revealed E2F targets pathway as the most highly enriched pathway induced by the ESR1 fusions. IHC revealed higher levels of pRb in ESR1-YAP1 and ESR1-PCDH11x xenograft tumors and subsequent CDK4/6 inhibition completely blocked tumor growth in an ESR1-YAP1 PDX model. Integrating RNA-seq with ChIP-seq data, we discovered a set of EMT and metastasis genes bound by all ESR1 fusions and WT-ER, but whose expression was strongly and uniquely up-regulated only by the ESR1-YAP1 and ESR1-PCDH11x fusions. These studies also revealed gained sites bound only by the ESR1-YAP1 and ESR1-PCDH11x fusions, not bound by WT-ER nor ESR1-NOP2. Genes mapping to these sites have a role in metastatic biology and were highly up-regulated by the YAP1 and PCDH11x fusions, potentially mediated by long range transcriptional activation.

Conclusion. ESR1-YAP1 and ESR1-PCDH11x are driver fusions that occur in drug-resistant, advanced stage breast cancer and are a new class of recurrent somatic mutation that can cause acquired endocrine therapy resistance, yet can be treated with CDK4/6 inhibition. These driver fusions also confer increased metastatic ability through their ability to drive expression of genes that contribute to EMT and metastasis. In contrast, ESR1-NOP2 did not produce functional protein and appears to be a passenger event. These studies may provide pre-clinical rationale for targeting ESR1 translocated breast tumors, since the presence of an ESR1 driver fusion places a patient in a therapeutic category where none of the currently available endocrine therapies are likely to be effective.

Citation Format: Lei JT, Shao J, Zhang J, Iglesia M, Chan DW, Cao J, Anurag M, Singh P, Haricharan S, Kavuri SM, Matsunuma R, Schmidt C, Kosaka Y, Crowder R, Hoog J, Phommaly C, Goncalves R, Ramalho S, Rodrigues-Peres RM, Lai W-C, Hampton O, Rogers A, Tobias E, Parikh P, Davies S, Ma C, Suman V, Hunt K, Watson M, Hoadley KA, Thompson A, Perou CM, Creighton CJ, Maher C, Ellis MJ. ESR1 gene fusions drive endocrine therapy resistance and metastasis in 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 PD8-03.

Evaluation of the Interplanetary Magnetic Field Strength Using the Cosmic-Ray Shadow of the Sun

We analyze the Sun's shadow observed with the Tibet-III air shower array and find that the shadow's center deviates northward (southward) from the optical solar disk center in the "away" ("toward") interplanetary magnetic field (IMF) sector. By comparing with numerical simulations based on the solar magnetic field model, we find that the average IMF strength in the away (toward) sector is 1.54±0.21_{stat}±0.20_{syst} (1.62±0.15_{stat}±0.22_{syst}) times larger than the model prediction. These demonstrate that the observed Sun's shadow is a useful tool for the quantitative evaluation of the average solar magnetic field.

[Comparative analysis of open surgical repair and endovascular aortic repair in the treatment of abdominal aortic aneurysm implicated visceral arteries]

Objective: To evaluate the value of open surgery repair and endovascular aortic repair in the treatment of abdominal aortic aneurysm which implicate visceral arteries. Methods: From January 2012 to October 2016, 26 patients were reviewed. According to the treatment, they were divided into open surgery group (n=7) and endovascular repair group(n=19). Then, the characteristics and relative data of follow-up of the two groups were analysis. Results: In open surgery group, there were 7 patients. All of them were men, median age 58(41-62) years and 1 patient were older than 75 years. And in endovascular repair group, there were 19 patients(14 men) of median age 72(66-76) years, 8 patients were older than 75 years. Patients in endovascular repair group were significantly older than who were in open surgery group (Z=-13.06, P<0.05). Complications of open surgery group and endovascular repair group were 57.14% and 15.79% respectively. There was no statistically significant difference (χ(2)=3.13, P>0.05). During follow-up, the diameters of aneurysm which planted stents were smaller than before. Conclusions: In the treatment of abdominal aortic aneurysm implicated visceral arteries, open surgery is mainly suitable for the patients with low-risk. But the rate of complications was high. By contrast, endovascular aortic repair with small trauma and high safety, has becoming the first choice.

Structural evolution during calcination and sintering of a (La0.6Sr0.4)0.99CoO3-δ nanofiber prepared by electrospinning

Design of three-dimensional metal oxide nanofibers by electrospinning is being widely explored. However, the impacts of calcination and sintering on the resulting morphology remain unknown. For the first time, (La_0.6Sr_0.4)_0.99CoO_3-δ (LSC) nanofiber, which is among the most promising electrode materials for solid oxide fuel cells, was synthesized by sol-gel electrospinning. By elevating the temperature in oxygen using in situ transmission electron microscopy, we discovered the structural transitions from nanofibers to nanotubes and then to nano-pearl strings. This facile and up-scalable method can be widely applied to design metal oxide one-dimensional nanomaterials with precise control in both geometry (nanofiber, nanotube and nano-pearl string) and surface area (by varying grain size).