PRMT5 controls pathogenicity and metabolic genes during Th17 polarization

PRMT5 catalyzes symmetric dimethylation (SDM) on arginine residues. PRMT5 methylates histone H3 and H4 producing remodeling of chromatin and regulation of gene transcription. PRMT5 is induced after T cell activation. Furthermore, both PRMT5 inhibitors and PRMT5 knockdown impair T cell proliferation and activation. However, the role of PRMT5 in T cell differentiation has not been analyzed. T cells undergo metabolic reprograming during activation which is critical for polarization. Differentiating T cells increase bioenergetics and anabolic pathways enhancing glycolysis, catabolism, uptake of fatty acids and oxidative phosphorylation. Whether PRMT5 has an impact on Th17 differentiation and metabolic reprograming is unknown. To address this question, we performed Th17 differentiation and RNA sequencing analyses in T cells from PRMT5fl/fl and iCD4-PRMT5Δ/Δ mice. Th17 differentiation was sharply suppressed in PRMT5 KO T cells, in which 25–30% of genes in the glycolysis, lactate or TCA pathways were reduced. To evaluate the functional effects of PRMT5 on energy metabolism, extracellular acidification rate (ECAR) and Oxygen consumption rate (OCR) were analyzed in Jurkat T cells transduced with control or PRMT5 shRNA and lactate secretion was measured on supernatants of Th1 and Th17 cells from PRMT5fl/fl and iCD4-PRMT5Δ/Δ mice. Knock down of PRMT5 decreased ECAR in Jurkat cells and lactate production in Th1 and Th17 cells in absence of PRMT5. In conclusion, PRMT5 promotes glycolytic energy metabolism and Th17 differentiation in T cells.

PRMT5 has roles in thymic/peripheral T cell development and EAE

Protein Arginine Methyltransferase (PRMT) 5 is a type-II methyltransferase involved in oncogenesis, embryonic and hematopoietic development. However, the role of PRMT5 T-cell biology is only now coming into focus. To evaluate PRMT5’s functions in T-cells, we have developed a conditional knock-out (KO) model that allow for a deletion of PRMT5 during thymic development, by knocking-out PRMT5 in all peripheral T cells (T-PRMT5D/D). Using this model that deletes both protein-coding isoforms of Prmt5, we investigated the role of the PRMT5 gene during T-cell development, proliferation and experimental autoimmune encephalomyelitis (EAE). We saw reduced numbers of CD4+ T-cells, Tregs and iNK T-cells in the thymus. CD4+, Treg and iNK T-cell number defects were seen in the peripheral lymphoid organs such as spleen and lymph nodes. Peripheral analyses also showed reduced CD8+ T-cells, naive, effector and central memory CD4+ T-cells. We also induced PRMT5 deletion specifically in peripheral CD4+ T cells (iCD4-PRMT5D/D). We utilize this model to induce PRMT5 deletion specifically in peripheral CD4+ T cells while ensuring that the mice develop normal numbers of peripheral T cells. Using this model, we showed that EAE was completely abolished in the mice. Total CNS infiltrating T-cell numbers were substantially reduced, and significant losses were observed in the Th1 and Th17 cytokine production from these cells. These data substantively demonstrate a driver role for PRMT5 in thymic CD4 Th cell development, peripheral CD4+, iNKT and CD8+ T-cell maintenance and Th cell-mediated EAE autoimmunity.

Role of PRMT5 in cholesterol metabolism and Th17 pathogenicity

Protein Arginine Methyltransferase (PRMT) 5 is an enzyme catalyzing symmetric dimethylation (SDM) of arginine. This post-translational modification is known to be involved in oncogenesis and embryonic development. Our previous work has shown that PRMT5 is induced during T cell activation. However, the role and mechanisms by which PRMT5 modulates T helper (Th) cell polarization and autoimmune disease have not yet been elucidated. To study the impact of PRMT5 on gene expression programs induced in activated T cells, we developed a conditional PRMT5 knockout (KO) mouse model in which PRMT5 deletion can be induced in CD4+ T cells after thymic development and performed RNA sequencing (RNAseq) analyses in 3-day activated naïve CD4 T cells. We found that PRMT5 promoted expression of cholesterol biosynthetic pathway enzymes that produce Retinoid-Related Orphan Receptor (ROR) agonists that activate ROR-gt and promote Th17 differentiation. Indeed, Th17 differentiation was blunted in PRMT5 KO T cells. Finally, we identify the cholesterol biosynthesis pathway regulator SREBP-1 as a target of PRMT5 SDM. This work shows that PRMT5 expression in activated T cells is needed for the cholesterol biosynthesis gene expression program, generating ROR-gt agonistic activity and promoting Th17 differentiation. These results point to T cell PRMT5 and the downstream cholesterol biosynthesis pathway as promising therapeutic targets in Th17 cell-based diseases.

International Nosocomial Infection Control Consortium (INICC) report, data summary of 45 countries for 2012-2017: Device-associated module

BACKGROUND

We report the results of International Nosocomial Infection Control Consortium (INICC) surveillance study from January 2012 to December 2017 in 523 intensive care units (ICUs) in 45 countries from Latin America, Europe, Eastern Mediterranean, Southeast Asia, and Western Pacific.

METHODS

During the 6-year study period, prospective data from 532,483 ICU patients hospitalized in 242 hospitals, for an aggregate of 2,197,304 patient days, were collected through the INICC Surveillance Online System (ISOS). The Centers for Disease Control and Prevention-National Healthcare Safety Network (CDC-NHSN) definitions for device-associated health care-associated infection (DA-HAI) were applied.

RESULTS

Although device use in INICC ICUs was similar to that reported from CDC-NHSN ICUs, DA-HAI rates were higher in the INICC ICUs: in the medical-surgical ICUs, the pooled central line-associated bloodstream infection rate was higher (5.05 vs 0.8 per 1,000 central line-days); the ventilator-associated pneumonia rate was also higher (14.1 vs 0.9 per 1,000 ventilator-days,), as well as the rate of catheter-associated urinary tract infection (5.1 vs 1.7 per 1,000 catheter-days). From blood cultures samples, frequencies of resistance, such as of Pseudomonas aeruginosa to piperacillin-tazobactam (33.0% vs 18.3%), were also higher.

CONCLUSIONS

Despite a significant trend toward the reduction in INICC ICUs, DA-HAI rates are still much higher compared with CDC-NHSN's ICUs representing the developed world. It is INICC's main goal to provide basic and cost-effective resources, through the INICC Surveillance Online System to tackle the burden of DA-HAIs effectively.

Protein arginine methyltransferase 5 promotes cholesterol biosynthesis-mediated Th17 responses and autoimmunity

Protein arginine methyltransferase 5 (PRMT5) catalyzes symmetric dimethylation (SDM) of arginine, a posttranslational modification involved in oncogenesis and embryonic development. However, the role and mechanisms by which PRMT5 modulates Th cell polarization and autoimmune disease have not yet been elucidated. Here, we found that PRMT5 promoted SREBP1 SDM and the induction of cholesterol biosynthetic pathway enzymes that produce retinoid-related orphan receptor (ROR) agonists that activate RORγt. Specific loss of PRMT5 in the CD4+ Th cell compartment suppressed Th17 differentiation and protected mice from developing experimental autoimmune encephalomyelitis (EAE). We also found that PRMT5 controlled thymic and peripheral homeostasis in the CD4+ Th cell life cycle and invariant NK (iNK) T cell development and CD8+ T cell maintenance. This work demonstrates that PRMT5 expression in recently activated T cells is necessary for the cholesterol biosynthesis metabolic gene expression program that generates RORγt agonistic activity and promotes Th17 differentiation and EAE. These results point to Th PRMT5 and its downstream cholesterol biosynthesis pathway as promising therapeutic targets in Th17-mediated diseases.

Neoadjuvant radiotherapy in rectal cancer - less is more?

AIM

There is significant international variation in the use of neoadjuvant radiation prior to total mesorectal excision. The MERCURY group advocate selective neoadjuvant chemoradiotherapy (CRT). We have performed a retrospective, single-centre study of patients treated with CRT, where only the circumferential resection margin is threatened, with the aim of identifying whether a more selective approach to CRT provides acceptable local relapse rates (LRRs).

METHOD

All consecutive patients who underwent radical surgery for rectal adenocarcinoma over a 5-year period (2007-2012) in the Oxford University Trust were considered. Electronic hospital systems were reviewed to obtain patient and tumour demographics, treatment and follow-up information. All patients were classified into risk categories according to National Institute for Health and Care Excellence guidance. Data were analysed using Microsoft Excel and R.

RESULTS

Two hundred and seventy-two patients were identified: 123, 89 and 60 in the high-, intermediate- and low-risk categories, respectively. Seventy-nine per cent of those in the high-risk group, 6% in the intermediate and 5% in the low-risk group underwent CRT. The overall 5-year LRR and distant recurrence rate (DRR) were 5.2% and 17.8%, respectively. The 5-year LRR for those who went straight to surgery was 2.0% and for those who had neoadjuvant CRT it was 7.4%. The DRR for these two groups was 8.5% and 18.9%, respectively.

CONCLUSION

Our series demonstrates that the use of CRT only in margin-threatening tumours, results in an exceptionally low LRR for those without margin-threatening disease. In routine clinical care, this strategy can minimize the significant morbidity of multimodal treatment and allow earlier introduction of systemic therapy to minimize distant recurrence.

R0 Resection Margin, A New Quality Measure in the Era of National Bowel Screening?

Aims To determine the completeness of polyp resection (i.e. achieving an R0 margin) and its relation with Endoscopists, histopathologist, size, location and technique of polypectomy in an NSS cohort. The definition of R0 margin is complete macroscopic resection with a negative microscopic margin at polypectomy. Method NCCS (National Colon Cancer Screening) colonoscopies are offered to bowel cancer screening patients after a positive faecal immunochemical test (FIT) test in a Joint Advisory Group (JAG) accredited Gastrointestinal Endoscopy centre. We histologically evaluated the polyp margins for complete resection, which was defined as the absence of adenomatous or hyperplastic tissue in the resected polyp margins in a cohort of faecal immunochemical test positive patients. Results A total of 186 consecutive NCCS colonoscopies out of a total of 542 performed between 2013 and 2017 were included in this study. Of the polyps excised 152(27%) had a R0 margin histologically, and 30(5%) had involvement of the margin. Surprisingly in 373(67%) of polyps pathologists were unable to assess the margin. Conclusion Achieving an R0 margin should be a key performance indicator for endoscopists performing polypectomy. At the same time more studies on polyp margins are recommended.

EAU-ESMO consensus statements on the management of advanced and variant bladder cancer-an international collaborative multi-stakeholder effort: under the auspices of the EAU and ESMO Guidelines Committees†

BACKGROUND

Although guidelines exist for advanced and variant bladder cancer management, evidence is limited/conflicting in some areas and the optimal approach remains controversial.

OBJECTIVE

To bring together a large multidisciplinary group of experts to develop consensus statements on controversial topics in bladder cancer management.

DESIGN

A steering committee compiled proposed statements regarding advanced and variant bladder cancer management which were assessed by 113 experts in a Delphi survey. Statements not reaching consensus were reviewed; those prioritised were revised by a panel of 45 experts before voting during a consensus conference.

SETTING

Online Delphi survey and consensus conference.

PARTICIPANTS

The European Association of Urology (EAU), the European Society for Medical Oncology (ESMO), experts in bladder cancer management.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Statements were ranked by experts according to their level of agreement: 1-3 (disagree), 4-6 (equivocal), 7-9 (agree). A priori (level 1) consensus was defined as ≥70% agreement and ≤15% disagreement, or vice versa. In the Delphi survey, a second analysis was restricted to stakeholder group(s) considered to have adequate expertise relating to each statement (to achieve level 2 consensus).

RESULTS AND LIMITATIONS

Overall, 116 statements were included in the Delphi survey. Of these, 33 (28%) statements achieved level 1 consensus and 49 (42%) statements achieved level 1 or 2 consensus. At the consensus conference, 22 of 27 (81%) statements achieved consensus. These consensus statements provide further guidance across a broad range of topics, including the management of variant histologies, the role/limitations of prognostic biomarkers in clinical decision making, bladder preservation strategies, modern radiotherapy techniques, the management of oligometastatic disease and the evolving role of checkpoint inhibitor therapy in metastatic disease.

CONCLUSIONS

These consensus statements provide further guidance on controversial topics in advanced and variant bladder cancer management until a time where further evidence is available to guide our approach.

High Performance Bi-2212 Round Wires Made with Recent Powders

Multifilamentary Bi₂Sr₂CaCu₂O_x (Bi-2212) wire made by the powder-in-tube technique is the only high temperature superconductor made in the round shape preferred by magnet builders. The critical current density (J _C ) of Bi-2212 round wire was improved significantly by the development of overpressure heat treatment in the past few years. Bi-2212 wire is commercially available in multiple architectures and kilometer-long pieces and a very promising conductor for very high field NMR and accelerator magnets. We studied the effects of precursor powder and heat treatment conditions on the superconducting properties and microstructure of recent Bi-2212 wires. Short samples of recent wire with optimized overpressure processing showed J _C (4.2 K, 15 T) = 6640 A/mm² and J _C (4.2 K, 30 T) = 4670 A/mm², which correspond to engineering critical current densities J _E (4.2 K, 15 T) = 1320 A/mm² and J _E (4.2 K, 30 T) = 930 A/mm².

Spectral and Structural Variations of Biomimetic Light-Harvesting Nanotubes

Bioinspired, self-assembled nanotubes have been investigated by low-temperature, polarization-resolved single-tube spectroscopy. These assemblies are based on zinc chlorin monomers and are considered as model systems that resemble the secondary structural elements in the natural light-harvesting systems of green (non)sulfur bacteria. Compared to the natural systems, the spectral parameters extracted from the single-nanotube spectra feature distributions with significantly smaller widths, which is ascribed to a tremendous reduction of structural heterogeneity in the artificial systems. Employing quantum chemical molecular modeling the spectra of individual nanotubes can be explained consistently only for a molecular packing model that is fundamentally different from those considered so far for the natural systems. Subsequent theoretical simulations reveal that the remaining spectral variations between single nanotubes can be traced back to small variations of the mutual orientations of the monomer transition dipole moments that are far beyond the resolving power of high-resolution electron microscopy imaging techniques.

Variations in antibiotic use across India: multi-centre study through Global Point Prevalence survey

The aim of the study was to assess antimicrobial prescribing patterns, and variation in practice, in India. A point prevalence survey (PPS) was conducted in October to December 2017 in 16 tertiary care hospitals across India. The survey included all inpatients receiving an antimicrobial on the day of PPS and collected data were analysed using a web-based application of the University of Antwerp. In all, 1750 patients were surveyed, of whom 1005 were receiving a total of 1578 antimicrobials. Among the antimicrobials prescribed, 26.87% were for community-acquired infections; 19.20% for hospital-acquired infections; 17.24% for medical prophylaxis; 28.70% for surgical prophylaxis; and 7.99% for other or undetermined reasons. Antibiotic prescribing quality indicators, such as reason in notes and post-prescription review score, were low. This PPS showed widespread antibiotic usage, underlining the need for antibiotic stewardship to promote evidence-based practice.

NF-kB/mTOR/MYC axis drives PRMT5 protein induction after T cell activation

Multiple sclerosis (MS) is a debilitating autoimmune disease of the central nervous system (CNS) mediated by CD4+ T cells. Clinical data has provided evidence that MS patient T cells display an activated or memory phenotype and genome-wide association studies (GWAS) have identified single nucleotide polymorphisms linked to NF-kB complex and MYC genes in MS patients. These data imply a role for TcR (T cell receptor) signaling pathways in MS. PRMT5 is the major type II arginine methyltransferase catalyzing the symmetric dimethylation of histones and other proteins. Our lab has recently reported PRMT5 plays a crucial role in inflammatory T cell expansion and EAE disease. From cancer studies, we are aware of links between NF-kB/MYC signaling and PRMT5 induction. Here, we unravel the impact of NF-kB/MYC pathways in T cell PRMT5 expression and pathogenic T cell responses. We used naïve and memory mouse Th1/Th2 CD4+T cells as models to identify mechanisms controlling PRMT5 protein expression in initial and recall T cell activation. Naïve (initial) mouse T cell activation resulted in NF-kB-dependent transient Prmt5 transcription and NF-kB, mTOR and Myc-dependent PRMT5 protein induction. Recall activation in memory T cells showed rapid induction of PRMT5 protein expression, supported by both transcription and loss of Prmt5-targeting miRNAs. These results highlight the importance of the NF-kB/mTOR/MYC axis in PRMT5-driven pathogenic T cell expansion and may guide targeted therapeutic strategies for MS.

Contribution of Protein Arginine Methyltransferase (PRMT)5 to House Dust Mite Asthma

Severe asthma affects 2.4 million Americans and 23.8 million people worldwide and accounts for the majority of total asthma hospital costs. Most severe asthma is mediated by Th17/neutrophilic responses, alone or combined with Th2 and/or Th1 responses. In contrast, Treg responses are deficient. Protein Arginine Methyl Transferase (PRMT) 5 catalyzes symmetric dimethylation (SDM) of arginine on histones and other proteins, thereby regulating gene expression. PRMT5 promotes murine Th1/Th17 responses in central nervous system autoimmunity. However, its impact on asthma has not been established. We evaluated the role of PRMT5 on mouse models of house dust mite (HDM) asthma. PRMT5 and its symmetric demethylation activity were increased in lung infiltrating cells during Th2/Th17-mediated HDM severe asthma, suggesting a role for PRMT5 in asthma pathogenesis. To determine the contribution of PRMT5 to HDM asthma pathogenesis, we used first-in-class PRMT5-specific inhibitors developed at The Ohio State University. PRMT5 inhibitor HLCL65 modulated Th1, Th2 and Th17 differentiation and suppressed airway hyperreactivity in Th2/Th17 models of house dust mite (HDM)-induced asthma. Overall, these results support a role for PRMT5 in severe asthma pathogenesis.

NF-κB/mTOR/MYC Axis Drives PRMT5 Protein Induction After T Cell Activation via Transcriptional and Non-transcriptional Mechanisms

Multiple sclerosis is an autoimmune disease of the central nervous system (CNS) mediated by CD4⁺ T cells and modeled via experimental autoimmune encephalomyelitis (EAE). Inhibition of PRMT5, the major Type II arginine methyltransferase, suppresses pathogenic T cell responses and EAE. PRMT5 is transiently induced in proliferating memory inflammatory Th1 cells and during EAE. However, the mechanisms driving PRMT5 protein induction and repression as T cells expand and return to resting is currently unknown. Here, we used naive mouse and memory mouse and human Th1/Th2 cells as models to identify mechanisms controlling PRMT5 protein expression in initial and recall T cell activation. Initial activation of naive mouse T cells resulted in NF-κB-dependent transient Prmt5 transcription and NF-κB, mTOR and MYC-dependent PRMT5 protein induction. In murine memory Th cells, transcription and miRNA loss supported PRMT5 induction to a lesser extent than in naive T cells. In contrast, NF-κB/MYC/mTOR-dependent non-transcriptional PRMT5 induction played a major role. These results highlight the importance of the NF-κB/mTOR/MYC axis in PRMT5-driven pathogenic T cell expansion and may guide targeted therapeutic strategies for MS.

Abstract P2-06-14: The role of SLC7A5 (LAT1) in endocrine therapy-resistant breast cancer

Endocrine therapies are commonly used to treat estrogen receptor-positive (ER+) breast cancers, which comprise 70% of all new breast cancer cases. Unfortunately, emergence of resistance to these therapies presents a major clinical challenge. Cancer cells can adapt to the dysregulation of cellular metabolism induced by endocrine therapy in order to evade cell death.Central to this adaptation is the scavenging of free-formed amino acids from the tumor microenvironment. For example, we found 109 solute carrier (SLC) mRNAs to be differentially expressed between endocrine-sensitive and resistant cells. We began our mechanistic studies of these genes with SLC family 7 member 5 (SLC7A5 or LAT1). SLC7A5 is a key component of a transmembrane transporter, which can complex with CD98 and increase the uptake of large, neutral amino acids (such as leucine or tyrosine).

We used a panel of endocrine therapy-resistant (LCC9) and sensitive (MCF7; LCC1) breast cancer cells. SLC7A5 expression was upregulated by estrogen in MCF7 and LCC1 cells; this induction was blocked by fulvestrant treatment. Basal expression of the SLC7A5 protein in the absence of estrogen was 2.75-fold higher in LCC9 cells compared with MCF7 cells; SLC7A5 mRNA expression was 71-fold higher. Fulvestrant treatment did not significantly alter SLC7A5 mRNA or protein expression in LCC9 cells. Inhibiting SLC7A5 function using either a pharmacological inhibitor (JPH203), or depleting expression using siRNA, led to significant suppression of LCC9 cell growth. Cell cycle analysis revealed that SLC7A5 depletion caused cells to accumulate in the G1-phase, with a concurrent reduction of cells in S-phase. In four publicly available datasets of ER+, tamoxifen treated breast cancer patients, high expression of SLC7A5 was significantly associated with poor relapse-free survival.

This study uncovers a novel adaptive mechanism in endocrine therapy-resistant breast cancer cells that is facilitated by increased expression of SLC7A5, which enables them to supplement their increased metabolic needs and promoting cell growth. Blocking the functions of SLC7A5, perhaps in conjunction with inhibition of autophagy, may therefore offer a new avenue of potential therapeutic intervention against endocrine therapy-resistant breast cancers.

Citation Format: Sevigny CM, Sengupta S, Luo Z, Jin L, Pearce D, Clarke R. The role of SLC7A5 (LAT1) in endocrine therapy-resistant breast cancer [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 P2-06-14.

Abstract P5-04-17: Local network topology differences between early and late recurrence in ER+ breast cancers

Background: Late recurrence is characteristic of ER+ breast cancers. Despite an apparently effective adjuvant endocrine therapy, many breast cancers recur years after their initial endocrine treatment. Why some tumors recur early (<3 years) and some recur later (>5 years) is poorly understood. If systemic endocrine therapies killed all cells, recurrence would reflect only the appearance of new disease. Thus, we hypothesized that cells that survive and lie dormant may be driven, in part, by altered wiring of their cell death signaling. We, therefore, studied how cell death signaling is differentially wired in primary tumors that will recur early versus those that will recur later.

Method: Genes involved in apoptosis, autophagy, ferroptosis, necrosis, and pyroptosis were identified from KEGG to initiate network feature analysis of gene expression data from public and our first in-house gene expression dataset. Data were collected from ER+ breast cancer pre-endocrine treatment samples with up to 20 years follow-up. Publicly available datasets used were GSE6532, GSE2034, GSE7390, GSE17705, GSE12093, and TCGA. We applied our Knowledge-fused Differential Dependency Network (KDDN) analysis tool to the public datasets; KDDN has provided powerful new insights into signaling in breast and other cancers. Common gene-gene interactions (edges) predicted in at least two different datasets were extracted from all KDDN analyses results. To strengthen the relevance of these features, predicted network edges that represent known protein-protein interactions (PPI) were identified from the STRING database, and these edges were noted in the signaling graphs. Final network graphs were constructed using the common edges from all overlaid networks. We conducted IPA analysis on all nodes in the final network and selected those incorporating network hubs. We took a similar approach to our second in-house dataset, which we used for independent testing. Here, patients were included if their tumor exhibited an initial reduction in volume of at least 40% by four months in response to neo-adjuvant Letrozole. Patients were then classified into two groups during follow-up of up to 3.7 years: i) initial tumor size reduction followed by continued response (expected to recur late); ii) initial reduction followed by tumor regrowth (expected to recur early). KDDN analysis was performed on pretreatment samples from these two groups and a network created annotated with PPI information.

Results: MAPK8 and CYCS (Molecular Mechanisms of Cancer, p=1.58E-52), TNFRSF1A Neuroinflammation Signaling Pathway, p=1.26E-54), RELA, and NFKB1 (Colorectal Cancer Metastasis Signaling, p=7.94E-35), were identified as hubs. Hubs may be critical signaling components driving the differences between tumors that will become dormant and recur late. Connections between SLC25A6 and SQSTM1 (p = 0.008), BIRC2 and GABARAP (p = 0.021) in the early group, and AKT3 and IRS2 (p = 0.014) in the late group, were shared between the two final networks. With longer follow-up time on the second in-house dataset, we will better define the two groups and identify additional common phenotype specific gene-gene interactions.

Citation Format: Clarke R, Dixon M, Jin L, Pearce D, Turnbull A, Selli C, Hu R, Zwart A, Wang Y, Xuan J, Sengupta S, Sims A, Liu MC. Local network topology differences between early and late recurrence in ER+ breast cancers [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 P5-04-17.

Abstract P4-15-05: The presence of one or multiple foci of microinvasion is not associated with an increased risk of local recurrence in women with ductal carcinoma in situ treated with breast conserving therapy

Background: Ductal Carcinoma in Situ (DCIS) is a non-invasive breast cancer often treated with breast-conserving surgery (BCS) with or without radiotherapy (RT). It is unclear if the presence of microinvasion (MI) (invasion ≤1mm) is associated with an increased risk of LR (DCIS or invasive) or invasive LR compared to women with pure DCIS. In addition, the impact of multiple foci (>2) of MI compared to pure DCIS is also unknown; therefore, it is unclear if some women with MI require more aggressive treatment. We evaluated the impact of the presence of MI and the number of foci of MI on the risks of any LR and invasive LR in a population of women with DCIS with and without MI treated with BCS.

Methods: The cohort includes all women diagnosed with pure DCIS or DCIS with MI in Ontario from 1994-2003 treated with BCS +/- RT. All cases had systematic pathology review to confirm the presence and number of foci of MI. Treatment and outcomes were ascertained through administrative databases and validated by chart review. Cox proportional hazards model was used to evaluate the impact of MI and the number of foci of MI (1 vs >2 foci) on the development of any LR and invasive LR compared to cases with pure DCIS. The 10-yr local recurrence-free survival (LRFS) and invasive LRFS rates were calculated using the Kaplan-Meier approach with differences compared using the log-rank test.

Results: The population cohort includes 2,988 women with DCIS treated by BCS (N=2,721 pure DCIS, N= 267 DCIS with MI). Median follow-up (12 years; p=.23) and median age at diagnosis (58 years; p=.17) were similar in both groups. RT was given in 58% of cases with MI and 51% of cases with pure DCIS (p=.03). Hormonal therapy was utilized in 7.1% of women with MI and 5.3% of women with pure DCIS (p=.22). LR developed in 59 (22.1%) cases with MI and 530 (19.6%) cases of pure DCIS. Women with MI were more likely to have high nuclear grade (p<.001), and larger tumor size (p<.001) compared to those without MI. On multivariable analyses adjusted for age, the presence of 1 focus of MI(HR=.92, 95% CI: .64-1.33) or ≥2 foci of MI (HR=1.26, 95% CI: .85-1.85) was not associated with an increased risk of any LR compared to cases with pure DCIS. Factors associated with any LR were age <50 years at diagnosis, RT, multifocality and high nuclear grade. The presence of 1 focus of MI (HR=.86, 95% CI: .52-1.40) or > 2 foci of MI (HR=1.45, 95% CI: .90-2.32) was also not associated with an increased risk of invasive LR compared to cases of pure DCIS. Among women treated with BCS alone, the 10 year LRFS rates were 80%, 75% and 73% for women with pure DCIS, 1 focus, >2 foci of MI (p=.10). The invasive LRFS rates were 89%, 91% and 85% (p=.26). Among women treated with BCS+RT, the 10 year LRFS rates were 87%, 88% and 80% (p=0.32) for women with pure DCIS, 1 focus or ≥2 foci of MI. The invasive LRFS rates were 93%, 90% and 86% (p=.44). There was no interaction between the presence of MI and RT.

Conclusions: Women with DCIS with one or multiple foci of microinvasion (<1mm) treated by breast conserving therapy do not have an increased risk of LR or invasive LR compared to women with pure DCIS.

Citation Format: Lalani N, Paszat L, Sutradhar R, Gu S, Fong C, Nofech-Mozes S, Hanna W, Tuck A, Youngson B, Miller N, Done SJ, Chang MC, Sengupta S, Elavathil L, Jani PA, Bonin M, Rakovitch E. The presence of one or multiple foci of microinvasion is not associated with an increased risk of local recurrence in women with ductal carcinoma in situ treated with breast conserving therapy [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 P4-15-05.

Abstract P4-04-10: Molecular features of dormancy in ER+ breast cancers

Background:Late recurrence (emergence from dormancy) is characteristic of ER+ breast cancers. Despite adjuvant endocrine therapy, many breast cancers recur decades after their initial diagnosis and treatment. Why this occurs is poorly understood.

Methods: We studied 2 independent datasets of endocrine treated, ER+ breast cancers with up to 20 years follow-up. The 1st comprised matched samples from the primary tumor pretreatment at diagnosis and the first recurrence after or during adjuvant endocrine therapy (all FFPE). The 2nd dataset comprised pretreatment biopsies only (all snap frozen). For both datasets, high quality RNA was amplified, labelled, and subjected to transcriptome analysis using the Affymetrix technology (U133 Plus 2.0). Low quality data were identified using 'simpleaffy' and 'ffpe', and removed; all tools were from the R package unless otherwise noted. Remaining data were normalized using 'frma'. Genes differentially expressed between early (≤3 years) and late (≥ 5 years) were selected using limma. Unsupervised hierarchical clustering and PCA explored the structure of the data.

A similar molecular analysis was done on the 2nd dataset. A classification scheme that robustly separated early from late recurrences was validated in an independent public dataset of comparable patients, array platform, and frozen tissues. We also explored features in pretreatment samples that predetermined response duration.

Results: Genes that separated pretreatment specimens by recurrence time did not separate posttreatment specimens. Specimens did not cluster in patient pairs or by site of recurrence.

8245 genes were differentially expressed between early and late recurrences in the FFPE samples, while 2400 genes were significantly different in the same comparison in the frozen samples. Initial pathway analysis was done on each dataset independently using IPA (Ingenuity® Systems, www.ingenuity.com). 70 canonical pathways were identified in common between the two datasets (pretreatment). We then looked for genes regulated in both datasets (ignores FFPE and frozen tissue as source). There were 279 genes in common that differentially regulated in the same direction (upregulated; downregulated). IPA analysis of these genes identified 49 canonical pathways. We also explored the differentially expressed gene sets using 'GSEA' (www.software.broadinstitute.org/gsea/index.jsp). Pathways consistently associated with early vs. late recurrence include integrin signaling, the unfolded protein response, endoplasmic reticulum stress, actin-based motility, and estrogen biosynthesis.

Conclusion: Analysis of pretreatment tumors can predict early recurrences from those that will remain dormant and recur much later. Recurrent tumors exhibit a remodeled molecular landscape that likely reflects the effects of treatments and/or a recreation of a niche with potentially common features at the site of recurrence. Changes in molecular signaling associated with duration of recurrence are consistent with our experimental model studies in vitro implicating UPR signaling as a major integrator of response to endocrine therapy and duration of survival. Additional data sets are being arrayed and more detailed molecular signaling studies are in progress.

Citation Format: Clarke R, Dixon MJ, Jin L, Turnbull A, Hu R, Zwart A, Wang Y, Xuan J, Sengupta S, Renshaw L, Sims A, Liu MC. Molecular features of dormancy in ER+ breast cancers [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 P4-04-10.