Abstract P4-07-12: Development of Triple-negative breast cancer (TNBC) syngeneic models and TROP2-directed antibody-drug conjugate (ADC) surrogate to model therapeutic combinations

Background: Sacituzumab govitecan (SG, Trodelvy®) is a human trophoblast cell surface antigen 2 (TROP-2) directed antibody drug conjugate (ADC) coupled to an active form of irinotecan (SN-38) via our novel hydrolyzable linker (CL2A). SG is the only FDA-approved ADC treatment for TNBC patients in the second-line setting. TROP-2 is a transmembrane protein encoded by the tumor-associated calcium signal transducer 2 (TACSTD2) gene and highly expressed in TNBC, an aggressive type of cancer accounting for approximately 15% of all breast cancers. TROP-2 overexpression is associated with poor survival and relapse, but its biological function in TNBC remains poorly understood. Hypothesis/rationale: To better understand TROP-2 and TROP-2-directed ADC biology, we developed and characterized TROP2high vs TROP2low TNBC syngeneic tumors and an SG surrogate directed to murine TROP-2. Experimental design: We established 2 syngeneic TNBC models with differential TROP-2 expression: 4T1 cells were flow sorted into high (>95%) vs low (< 7%) TROP-2 expressors and EMT6 cells were transduced with a murine TACSTD2-encoding lentivirus. Balb/c mice were subcutaneously implanted with 0.5 × 10 E6 TROP-2high, TROP-2low, or parental tumor cells (4T1 or EMT6). Tumor immunophenotyping and transcriptomic analyses were performed 15 and 24 days after implantation. An SG mouse surrogate was engineered to mimic SG, using an anti-TROP-2 antibody (Rab64) that cross-reacts with human and murine TROP-2 covalently attached to SN-38 by the CL2A linker. SG surrogate activity was characterized in vitro and in 4T1 syngeneic models. Results: SG surrogate demonstrated high affinity for human and mouse TROP-2 (KD=1.1 and 1.4 nM, respectively) with SN-38 release rates and PK similar to that of SG. Flow cytometry analysis after bulk cell sorting of 4T1 or lentivirus transduction of EMT6 confirmed high TROP2 expression after at least 3 in vitro passages. Fifteen days after subcutaneous implantation, flow cytometry analysis of tumor single-cell suspensions revealed significant differences in immune infiltrates between 4T1-derived tumor groups (n=5/group; mean percentages in TROP2high vs TROP2low 4T1-derived tumors of cells expressing CD45: 65% vs 10%, P < 0.0001; CD8: 5.5% vs 1%, P = 0.0033; CD4: 22% vs 4%, P = 0.0055; macrophages: 12.5% vs 2.5%, P = 0.0002; myeloid cells: 52% vs 75%, P = 0.0066). In addition, TROP2high 4T1-derived tumors were smaller and had significantly less necrosis than TROP2low and unsorted 4T1-derived tumors 25 days after implantation. Finally, transcriptomics analyses of TROP2high vs TROP2low 4T1-derived tumors demonstrated the association of TACSTD2 expression levels with regulation of distinct molecular pathways. Conclusion: Syngeneic tumors derived from 4T1 cells with differential TROP2 expression levels are associated with differential cellular states and tumor microenvironment composition. In contrast, no significant phenotypic changes were observed in tumors derived from TACSTD2-transduced compared with mock-transduced EMT6 cells. Taken together, these results suggest that expression of the TACSTD2 gene is associated with, but not causative of, different tumor phenotypic states. Additional studies to investigate TROP-2 expression as a correlative marker of patient prognosis and the antitumor immune response are warranted. The effects of in vivo treatment with an SG surrogate on 4T1 tumor growth and immune phenotype will be discussed at the time of the presentation.

Citation Format: Chih-Chien Chou, Jordan Kardos, Becky Yang, Jessica Orf, Rutwij Dave, Yurong Lai, Chingwei V. Lee, Giuseppe A. Papalia, Kelli Boyd, Lauri Diehl, Nathalie Scholler. Development of Triple-negative breast cancer (TNBC) syngeneic models and TROP2-directed antibody-drug conjugate (ADC) surrogate to model therapeutic combinations [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 P4-07-12.

577 Non-clinical efficacy, pharmacokinetics, and pharmacodynamics of a novel bi-functional anti-CD73-TGFβRII-trap molecule in combination with immune checkpoint therapy

Background

A novel murine bi-functional molecule, G04-trap, comprised of an anti-CD73 antibody fused to the extracellular domain of TGFβ receptor II, is designed to potently antagonize two prominent immunosuppressive and pro-tumorigenic pathways present across a variety of cancer types. Inhibition of both CD73-adenosine and TGFβ pathways is expected to create favorable conditions within the tumor microenvironment and restore antitumor immune responses.

Methods

G04-trap was evaluated in Detroit562, MC38, and Hepa1-6 efficacy tumor models. Tumor growth inhibition (TGI) was determined when >/=9 animals were alive in each group. Tumor-bearing mice received isotype control (200 microgram), G04-trap (246 microgram), anti-PD-(L)1 (200 microgram) or G04-trap + anti-PD-(L)1 twice per week for 3 weeks. Pharmacokinetic (PK) and pharmacodynamic (PD) assessment was performed on MC38 tumor-bearing mice dosed with 3 mg/kg, 10 mg/kg, or 30 mg/kg G04-trap. Plasma and tumor PK, CD73 target occupancy on T cells, plasma TGFβ, plasma free-sCD73, and tumor CD73 activity were measured after a single dose administration of G04-trap

Results

Administration of G04-trap to mice harboring TGFβ-dependent human pharyngeal Detroit562 xenograft tumors led to a dose-dependent anti-tumor response (83% TGI, at 246 microgram vs. isotype control on day 21). In addition, treatment with G04-trap in combination with immune checkpoint inhibition showed anti-tumor activity in MC38 and Hepa1-6 syngeneic mouse models. In MC38 on day 18, there was a statistically significant TGI with G04-trap + anti-PD-L1 (99% TGI vs. isotype control or 98% TGI vs. anti-PD-L1 alone). A more modest effect was observed in Hepa1-6, with 47% TGI in mice receiving G04-trap + anti-PD-1 vs. isotype control on day 27. To further interpret the efficacy observed in the MC38 tumor model, we performed in-depth PK/PD analysis. Intravenous administration of G04-trap at 3-30 mg/kg resulted in 10% tumor-to-plasma exposure ratio. Full TGFβ target coverage and full CD73 target occupancy on blood T cells was sustained for >3 days, supporting a BIW dosing schedule in non-clinical studies. Treatment also resulted in a dose-dependent inhibition of CD73 activity in tumors. In contrast to cellular CD73, a dose-dependent increase in free sCD73 concentration above baseline was measured in the plasma, consistent with previous reports evaluating anti-CD73 antibodies [1].

Conclusions

Dual inhibition of CD73 and TGFβ in combination with immune checkpoint blockade resulted in enhanced anti-tumor activity in xenograft and syngeneic tumor models. These results suggest that further exploration of this approach is warranted.

References

Zhao Y, Gu H, Postelnek J, DeMichele M, Yuan L, Zhang YJ, et al. Fit-for-purpose protein biomarker assay validation strategies using hybrid immunocapture-liquid chromatography-tandem-mass spectrometry platform: Quantitative analysis of total soluble cluster of differentiation 73. Anal Chim Acta. 2020;1126:144–53.

Chatbots to Support Mental Wellbeing of People Living in Rural Areas: Can User Groups Contribute to Co-design?

Digital technologies such as chatbots can be used in the field of mental health. In particular, chatbots can be used to support citizens living in sparsely populated areas who face problems such as poor access to mental health services, lack of 24/7 support, barriers to engagement, lack of age appropriate support and reductions in health budgets. The aim of this study was to establish if user groups can design content for a chatbot to support the mental wellbeing of individuals in rural areas. University students and staff, mental health professionals and mental health service users (N = 78 total) were recruited to workshops across Northern Ireland, Ireland, Scotland, Finland and Sweden. The findings revealed that participants wanted a positive chatbot that was able to listen, support, inform and build a rapport with users. Gamification could be used within the chatbot to increase user engagement and retention. Content within the chatbot could include validated mental health scales and appropriate response triggers, such as signposting to external resources should the user disclose potentially harmful information or suicidal intent. Overall, the workshop participants identified user needs which can be transformed into chatbot requirements. Responsible design of mental healthcare chatbots should consider what users want or need, but also what chatbot features artificial intelligence can competently facilitate and which features mental health professionals would endorse.

Neurovascular coupling and oxygenation are decreased in hippocampus compared to neocortex because of microvascular differences

The hippocampus is essential for spatial and episodic memory but is damaged early in Alzheimer's disease and is very sensitive to hypoxia. Understanding how it regulates its oxygen supply is therefore key for designing interventions to preserve its function. However, studies of neurovascular function in the hippocampus in vivo have been limited by its relative inaccessibility. Here we compared hippocampal and visual cortical neurovascular function in awake mice, using two photon imaging of individual neurons and vessels and measures of regional blood flow and haemoglobin oxygenation. We show that blood flow, blood oxygenation and neurovascular coupling were decreased in the hippocampus compared to neocortex, because of differences in both the vascular network and pericyte and endothelial cell function. Modelling oxygen diffusion indicates that these features of the hippocampal vasculature may restrict oxygen availability and could explain its sensitivity to damage during neurological conditions, including Alzheimer's disease, where the brain's energy supply is decreased.

Prostaglandin I2 signaling licenses Treg suppressive function and prevents pathogenic reprogramming

Tregs restrain both the innate and adaptive immune systems to maintain homeostasis. Allergic airway inflammation, characterized by a Th2 response that results from a breakdown of tolerance to innocuous environmental antigens, is negatively regulated by Tregs. We previously reported that prostaglandin I2 (PGI2) promoted immune tolerance in models of allergic inflammation; however, the effect of PGI2 on Treg function was not investigated. Tregs from mice deficient in the PGI2 receptor IP (IP KO) had impaired suppressive capabilities during allergic airway inflammatory responses compared with mice in which PGI2 signaling was intact. IP KO Tregs had significantly enhanced expression of immunoglobulin-like transcript 3 (ILT3) compared with WT Tregs, which may contribute to the impairment of the IP KO Treg's ability to suppress Th2 responses. Using fate-mapping mice, we reported that PGI2 signaling prevents Treg reprogramming toward a pathogenic phenotype. PGI2 analogs promoted the differentiation of naive T cells to Tregs in both mice and humans via repression of β-catenin signaling. Finally, a missense variant in IP in humans was strongly associated with chronic obstructive asthma. Together, these data support that PGI2 signaling licenses Treg suppressive function and that PGI2 is a therapeutic target for enhancing Treg function.

Myofunctional therapy. Part 1: Culture, industrialisation and the shrinking human face

Culture, industrialisation and the shrinking human face: Why is it important? Over the past 300,000 years, not only has the way we consume food from birth through our lifetime changed, there have also been changes related to the methods of food preparation, availability, processing, and storage. These diet-related factors, along with other epigenetic factors, have led to a widespread increase in orofacial myofunctional disorders (OMDs) and resultant human malocclusion phenotypes (HMPs) worldwide. Currently there is an increasing need for resolution of HMPs in early childhood and associated OMDs. This review will include reports of cases and describe the nature of the problem and strategies for effective solutions.

BET Inhibition Enhances the Antileukemic Activity of Low-dose Venetoclax in Acute Myeloid Leukemia

PURPOSE

The BCL2 inhibitor, venetoclax, has transformed clinical care in acute myeloid leukemia (AML). However, subsets of patients do not respond or eventually acquire resistance. Venetoclax-based regimens can lead to considerable marrow suppression in some patients. Bromodomain and extraterminal inhibitors (BETi) are potential treatments for AML, as regulators of critical AML oncogenes. We tested the efficacy of novel BET inhibitor INCB054329, and its synergy with venetoclax to reduce AML without induction of hematopoietic toxicity.

EXPERIMENTAL DESIGN

INCB054329 efficacy was assessed by changes in cell cycle and apoptosis in treated AML cell lines. In vivo efficacy was assessed by tumor reduction in MV-4-11 cell line-derived xenografts. Precision run-on and sequencing (PRO-seq) evaluated effects of INCB054329. Synergy between low-dose BETi and venetoclax was assessed in cell lines and patient samples in vitro and in vivo while efficacy and toxicity was assessed in patient-derived xenograft (PDX) models.

RESULTS

INCB054329 induced dose-dependent apoptosis and quiescence in AML cell lines. PRO-seq analysis evaluated the effects of INCB054329 on transcription and confirmed reduced transcriptional elongation of key oncogenes, MYC and BCL2, and genes involved in the cell cycle and metabolism. Combinations of BETi and venetoclax led to reduced cell viability in cell lines and patient samples. Low-dose combinations of INCB054329 and venetoclax in cell line and PDX models reduced AML burden, regardless of the sensitivity to monotherapy without development of toxicity.

CONCLUSIONS

Our findings suggest low dose combinations of venetoclax and BETi may be more efficacious for patients with AML than either monotherapy, potentially providing a longer, more tolerable dosing regimen.

1408. Enterovirus D68 RNA Visualized in the Anterior Horn of the Spinal Cord of a Pediatric Patient with Flaccid Paralysis

Background

Acute flaccid myelitis (AFM) is a polio-like paralyzing illness of children. AFM incidence is increasing during every other year outbreaks that occur in the United States simultaneously with outbreaks of enterovirus D68 (EV-D68) infection. Demonstrating that EV-D68 directly causes AFM has been challenging due to rare detection of the virus in the cerebrospinal fluid (CSF) of patients despite frequent detection at nonsterile sites. Murine studies have shown that EV-D68 can infect spinal cord anterior horn motor neurons and cause paralysis, similar to poliovirus. However, a key outstanding question is whether EV-D68 causes AFM in humans by direct viral pathogenesis or by indirect host immunopathogenesis.

Methods

We investigated the pathogenesis of AFM using tissues from a previously reported case of a 5-year-old boy who presented in fall 2008 with four days of progressive limb and voice weakness followed by incontinence, apnea, and death. He had a CSF pleocytosis of 2094/µL with EV-D68 identified in the CSF by sequencing of the VP1 gene. We designed probes for in situ hybridization (ISH) based on this sequence to stain formalin fixed paraffin embedded tissues from his autopsy. For immunohistochemistry (IHC) we used both commercial polyclonal anti-EV-D68 antibodies and our own human monoclonal antibodies that stain virus infected cells in vitro. Immunophenotyping was done by IHC.

Results

With ISH we identified EV-D68 RNA in the anterior horn of the patient’s spinal cord, corresponding to the location of motor neuron cell bodies. This area was highly inflamed, with an infiltrate of lymphocytes and macrophages. Viral RNA was in low abundance, and we could not detect viral surface proteins by IHC. Neither RNA nor viral antigen was detected in the lungs, which had extensive inflammatory infiltrate.

Conclusion

Deaths in AFM patients are rare and often distant from initial presentation, but this patient died four days after onset of weakness, allowing us to directly demonstrate that EV-D68 can infect the human spinal cord. Low abundance of virus suggests the virus either reached the spinal cord prior to weakness onset or was cleared rapidly by the immune response. Therefore, both direct viral pathology and immune factors likely contribute to AFM disease in EV-D68 infection.

Disclosures

James E. Crowe, Jr, MD, IDBiologics (Board Member, Consultant, Grant/Research Support)Vanderbilt University (Other Financial or Material Support, Inventor on patent related to this abstract)

Oral Azacitidine and Cedazuridine Approximate Parenteral Azacitidine Efficacy in Murine Model

Background

DNA methyltransferase inhibitors (DNMTis) improve survival for patients with myelodysplastic syndromes (MDS) and those with acute myeloid leukemia (AML) unable to receive standard cytotoxic chemotherapy and are, accordingly, the backbone of standard-of-care treatment for these conditions. Standard regimens with DNMTIs, decitabine (DEC) or azacitidine (AZA) include daily subcutaneous (s.c.) or intravenous (i.v.) administration for 5–7 consecutive days. Attempts to provide the therapy orally have been limited given rapid clearance of the agents by the enzyme cytidine deaminase (CDA), which is ubiquitous in the gut and liver as part of first-pass metabolism. Recently, cedazuridine (CDZ), an oral inhibitor of CDA, was successfully combined with DEC to approximate the pharmacokinetics of i.v. DEC in patients.

Objective

To determine if an oral dosing strategy might be feasible in the clinic with AZA, we attempted to increase the bioavailability of oral AZA through the use of CDZ, in a murine model.

Methods

Following pharmacokinetic and pharmacodynamic assessment of oral AZA dosed with CDZ in murine and monkey models, we tested this regimen in vivo with a human cell line-derived xenograft transplantation experiment (CDX). Following this we combined the regimen with venetoclax (VEN) to test the efficacy of an all-oral regimen in a patient-derived xenograft (PDX) model.

Results

Parenteral AZA and oral AZA + CDZ exhibited similar pharmacokinetic profiles, and efficacy against human AML cells. Tumor regression was seen with AZA + CDZ in MOLM-13 CDX and PDX models.

Conclusions

We conclude that oral AZA when combined with CDZ achieves successful tumor regression in both CDX and PDX models. Furthermore, the combination of AZA + CDZ with VEN in a PDX model emulated responses seen with VEN + AZA in the clinic, implying a potential all-oral VEN-based therapy opportunity in myeloid diseases.

Economic impacts of implementing a national smoke-free prison policy

Background

Worldwide, over 600,000 non-smokers are killed annually due to exposure to secondhand smoke (SHS); the UK societal cost of SHS is estimated at £700million per annum. Prior to recent smoke free policy in Scottish prisons smoking rates were very high (70-75%), well above population rates, subjecting people in custody (PiC) and prison staff to high levels of SHS. Eradicating SHS exposure in prisons could lead to improved health in previous smokers and non-smokers alike, and decrease demand on the National Health Service. However, to date, there is little evidence relating to the economic impact of smoking bans in prisons.

Methods

An economic evaluation estimating the short-term and lifetime impacts of smokefree prison policy in Scotland policy used data from the TIPs study (Jun 2016-Nov 2019) for prison staff and PiC. The analyses adopted a public health and personal perspective and key resources included: implementation costs, cessation support services, health service use and personal costs. For the short-term analyses data were sourced from TIPs staff and PiC surveys, and routine data from the Scottish Prison Service and NHS National Services Scotland. Outcomes included SHS exposure, staff sickness absence, violent incidents and quality adjusted life years (QALYs). The life-time analysis used a Markov model to estimate cost per QALY for both staff and PiC.

Results

SHS exposure measures show a median reduction of 91%. Costs and economic outcome results (mean cost pre- and post-ban, cost-consequences balance sheet and incremental cost per QALYs) are confidential until May 2020 due to their sensitivity and will be available to present at EUPHA 2020.

Conclusions

Previous economic evaluations have focussed on smoking bans in public places and raising the smoking age. This is the first economic analysis of a national prison smoking ban and analysis will be of interest to prison services in other jurisdictions which have yet to implement smokefree policy.

Smokefree policy and medication dispensing for people in prison: interrupted time series analysis

Background

Previous evaluations of smokefree prison policies have suggested improvements in self-rated health and some smoking-related symptoms. No studies to date have investigated impacts on medication use as proxy measures of objective ill-health or as indicators of potential negative unintended consequences. These is limited evidence to date on these important outcomes.

Methods

We obtained from NHS National Services Scotland aggregate data on medication items dispensed in prisons, based on individual named patient medication records, and from the Scottish Prison Service data on the prison population, for the period Jan 2013-Nov 2019. Items of interest comprised those for smoking cessation (varenicline and buproprion); nicotine replacement; specific smoking-related health conditions (glyceryl trinitrate; inhaled bronchodilators and steroids; antibiotics; chloramphenicol eye drops; and proton pump inhibitors and H2 receptor antagonists), and potential unintended mental health consequences (anti-depressants). We also included a set of negative controls for which dispensing was not expected to be affected by the new smokefree policy (anticonvulsants, excluding pregabalin and gabapentin). Analyses were undertaken using AutoRegressive Integrated Moving Average (ARIMA) time series methods, with the dates of the policy's announcement and of implementation included as pre-specified breakpoints.

Results

The results of ARIMA modelling of medication dispensing are confidential until May 2020 due to their sensitivity and will be available to present at WCPH 2020.

Conclusions

The use of routinely available dispensing data as an indicator of objective health impacts and potential negative unintended consequences provides novel insights into the effectiveness of smokefree prison policies. Results will be of interest to international jurisdictions considering such policies and to those seeking to harness the potential of administrative data for natural experiments.

Fine-Needle Aspiration-Based Patient-Derived Cancer Organoids

Patient-derived cancer organoids hold great potential to accurately model and predict therapeutic responses. Efficient organoid isolation methods that minimize post-collection manipulation of tissues would improve adaptability, accuracy, and applicability to both experimental and real-time clinical settings. Here we present a simple and minimally invasive fine-needle aspiration (FNA)-based organoid culture technique using a variety of tumor types including gastrointestinal, thyroid, melanoma, and kidney. This method isolates organoids directly from patients at the bedside or from resected tissues, requiring minimal tissue processing while preserving the histologic growth patterns and infiltrating immune cells. Finally, we illustrate diverse downstream applications of this technique including in vitro high-throughput chemotherapeutic screens, in situ immune cell characterization, and in vivo patient-derived xenografts. Thus, routine clinical FNA-based collection techniques represent an unappreciated substantial source of material that can be exploited to generate tumor organoids from a variety of tumor types for both discovery and clinical applications.

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Fine-needle aspiration (FNA) is safe, minimally invasive, and widely used clinically

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FNA is a source of material for organoid culture and personalized medicine

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This technique requires minimal processing, preserving histology, and immune cells

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Downstream applications: high-throughput screens, immune analysis, and xenografts

Bcl2-Expressing Quiescent Type B Neural Stem Cells in the Ventricular-Subventricular Zone Are Resistant to Concurrent Temozolomide/X-Irradiation

The ventricular-subventricular zone (V-SVZ) of the mammalian brain is a site of adult neurogenesis. Within the V-SVZ reside type B neural stem cells (NSCs) and type A neuroblasts. The V-SVZ is also a primary site for very aggressive glioblastoma (GBM). Standard-of-care therapy for GBM consists of safe maximum resection, concurrent temozolomide (TMZ), and X-irradiation (XRT), followed by adjuvant TMZ therapy. The question of how this therapy impacts neurogenesis is not well understood and is of fundamental importance as normal tissue tolerance is a limiting factor. Here, we studied the effects of concurrent TMZ/XRT followed by adjuvant TMZ on type B stem cells and type A neuroblasts of the V-SVZ in C57BL/6 mice. We found that chemoradiation induced an apoptotic response in type A neuroblasts, as marked by cleavage of caspase 3, but not in NSCs, and that A cells within the V-SVZ were repopulated given sufficient recovery time. 53BP1 foci formation and resolution was used to assess the repair of DNA double-strand breaks. Remarkably, the repair was the same in type B and type A cells. While Bax expression was the same for type A or B cells, antiapoptotic Bcl2 and Mcl1 expression was significantly greater in NSCs. Thus, the resistance of type B NSCs to TMZ/XRT appears to be due, in part, to high basal expression of antiapoptotic proteins compared with type A cells. This preclinical research, demonstrating that murine NSCs residing in the V-SVZ are tolerant of standard chemoradiation therapy, supports a dose escalation strategy for treatment of GBM. Stem Cells 2019;37:1629-1639.

Beyond Epilepsy and Autism: Disruption of GABRB3 Causes Ocular Hypopigmentation

Reduced ocular pigmentation is common in Angelman syndrome (AS) and Prader-Willi syndrome (PWS) and is long thought to be caused by OCA2 deletion. GABRB3 is located in the 15q11-13 region flanked by UBE3A, GABRA5, GABRG3, and OCA2. Mutations in GABRB3 have frequently been associated with epilepsy and autism, consistent with its role in neurodevelopment. We report here a robust phenotype in the mouse in which deletion of Gabrb3 alone causes nearly complete loss of retinal pigmentation due to atrophied melanosomes, as evidenced by electron microscopy. Using exome and RNA sequencing, we confirmed that only the Gabrb3 gene was disrupted while the Oca2 gene was intact. However, mRNA abundance of Oca2 and other genes adjacent to Gabrb3 is substantially reduced in Gabrb3^-/- mice, suggesting complex transcriptional regulation in this region. These results suggest that impairment in GABRB3 downregulates OCA2 and indirectly causes ocular hypopigmentation and visual defects in AS and PWS.

Mitochondrial protein Fus1/Tusc2 in premature aging and age-related pathologies: critical roles of calcium and energy homeostasis

Decreased energy production and increased oxidative stress are considered to be major contributors to aging and aging-associated pathologies. The role of mitochondrial calcium homeostasis has also been highlighted as an important factor affecting different pathological conditions. Here, we present evidence that loss of a small mitochondrial protein Fus1 that maintains mitochondrial homeostasis results in premature aging, aging-associated pathologies, and decreased survival. We showed that Fus1KO mice develop multiple early aging signs including lordokyphosis, lack of vigor, inability to accumulate fat, reduced ability to tolerate stress, and premature death. Other prominent pathological changes included low sperm counts, compromised ability of adult stem cells to repopulate tissues, and chronic inflammation. At the molecular level, we demonstrated that mitochondria of Fus1 KO cells have low reserve respiratory capacity (the ability to produce extra energy during sudden energy demanding situations), and show significantly altered dynamics of cellular calcium response.

Our recent studies on early hearing and memory loss in Fus1 KO mice combined with the new data presented here suggest that calcium and energy homeostasis controlled by Fus1 may be at the core of its aging-regulating activities. Thus, Fus1 protein and Fus1-dependent pathways and processes may represent new tools and targets for anti-aging strategies.

MLF1 is a proapoptotic antagonist of HOP complex-mediated survival

In the HAX1/HtrA2-OMI/PARL (HOP) mitochondrial protein complex, anti-apoptotic signals are generated by cleavage and activation of the serine protease HtrA2/OMI by the rhomboid protease PARL upon recruitment of both proteases to inner mitochondrial membrane protein HAX1 (HS1-associated protein X-1). Here we report the negative regulation of the HOP complex by human leukemia-associated myeloid leukemia factor 1 (MLF1). We demonstrate that MLF1 physically and functionally associates with HAX1 and HtrA2. Increased interaction of MLF1 with HAX1 and HtrA2 displaces HtrA2 from the HOP complex and inhibits HtrA2 cleavage and activation, resulting in the apoptotic cell death. Conversely, over-expressed HAX1 neutralizes MLF1's effect and inhibits MLF1-induced apoptosis. Importantly, Mlf1 deletion reverses B- and T-cell lymphopenia and significantly ameliorates the progressive striatal and cerebellar neurodegeneration observed in Hax1^-/- mice, with a doubling of the lifespan of Mlf1^-/-/Hax1^-/- animals compared to Hax1^-/- animals. Collectively, these data indicate that MLF1 serves as a proapoptotic antagonist that interacts with the HOP mitochondrial complex to modulate cell survival.

Haploinsufficiency of the Myc regulator Mtbp extends survival and delays tumor development in aging mice

Alterations of specific genes can modulate aging. Myc, a transcription factor that regulates the expression of many genes involved in critical cellular functions was shown to have a role in controlling longevity. Decreased expression of Myc inhibited many of the deleterious effects of aging and increased lifespan in mice. Without altering Myc expression, reduced levels of Mtbp, a recently identified regulator of Myc, limit Myc transcriptional activity and proliferation, while increased levels promote Myc-mediated effects. To determine the contribution of Mtbp to the effects of Myc on aging, we studied a large cohort of Mtbp heterozygous mice and littermate matched wild-type controls. Mtbp haploinsufficiency significantly increased longevity and maximal survival in mice. Reduced levels of Mtbp did not alter locomotor activity, litter size, or body size, but Mtbp heterozygous mice did exhibit elevated markers of metabolism, particularly in the liver. Mtbp^+/- mice also had a significant delay in spontaneous cancer development, which was most prominent in the hematopoietic system, and an altered tumor spectrum compared to Mtbp^+/+ mice. Therefore, the data suggest Mtbp is a regulator of longevity in mice that mimics some, but not all, of the properties of Myc in aging.

Preclinical Evaluation of 4-[18F]Fluoroglutamine PET to Assess ASCT2 Expression in Lung Cancer

PURPOSE

Alanine-serine-cysteine transporter 2 (ASCT2) expression has been demonstrated as a promising lung cancer biomarker. (2S,4R)-4-[(18)F]Fluoroglutamine (4-[(18)F]fluoro-Gln) positron emission tomography (PET) was evaluated in preclinical models of non-small cell lung cancer as a quantitative, non-invasive measure of ASCT2 expression.

PROCEDURES

In vivo microPET studies of 4-[(18)F]fluoro-Gln uptake were undertaken in human cell line xenograft tumor-bearing mice of varying ASCT2 levels, followed by a genetically engineered mouse model of epidermal growth factor receptor (EGFR)-mutant lung cancer. The relationship between a tracer accumulation and ASCT2 levels in tumors was evaluated by IHC and immunoblotting.

RESULT

4-[(18)F]Fluoro-Gln uptake, but not 2-deoxy-2-[(18)F]fluoro-D-glucose, correlated with relative ASCT2 levels in xenograft tumors. In genetically engineered mice, 4-[(18)F]fluoro-Gln accumulation was significantly elevated in lung tumors, relative to normal lung and cardiac tissues.

CONCLUSIONS

4-[(18)F]Fluoro-Gln PET appears to provide a non-invasive measure of ASCT2 expression. Given the potential of ASCT2 as a lung cancer biomarker, this and other tracers reflecting ASCT2 levels could emerge as precision imaging diagnostics in this setting.

Abstract 2404: Dysregulation of lung developmental pathways associated with LKB1 loss in lung cancer

Loss of the LKB1 tumor suppressor influences differentiation phenotypes in mouse models of lung adenocarcinoma and in human tumors. We utilize molecular data from resected human lung adenocarcinomas characterized by the TCGA to demonstrate that LKB1 deficient tumors exhibit a higher prevalence of neuroendocrine and gut-like differentiation markers than do LKB1 wild-type tumors (41% vs 9%, odds ratio = 7.3, P = 5.9E-19 for neuroendocrine differentiation; 36% vs 12%, odds ratio = 4.3, P = 2.5E-11 for gut-like differentiation. Fisher's exact test). Using copy number analysis and transcription factor enrichment analysis, we link these phenotypes to activation of particular transcription factors, namely FOXA2, HNF1A, ASCL1, and TTF1. We observe similar associations among non-small cell lung cancer cell lines, which may represent appropriate ideal models for further experimentation. Furthermore, we examine these differentiation phenotypes using immunohistochemical analysis of a tissue microarray (TMA), combined with RNAseq expression analysis, and MS/MS proteomic characterization of the same cohort of 36 tumors. Our molecular characterization confirms the neuroendocrine and gut-like differentiation phenotypes observed in the TCGA dataset and their association with LKB1-loss. Moreover, our immunohistochemical analysis demonstrates that these distinct differentiation subtypes are heterogeneously expressed within single tumors. Co-expression of neuroendocrine, gut-like, and respiratory differentiation is significantly more likely to occur within LKB1 deficient tumors, and is also associated with increased expression of a c-Kit positive sub-population that appears to lack expression of more differentiated markers. Among the TCGA tumors, this tri-lineage expression pattern is seen in 12.5% of LKB1-deficient tumors, compared to 1% of LKB1-wild-type tumors (Odds ratio 11.5, P = 3.2E-8. Fisher's exact test). These findings give further support to the role of LKB1 in regulating differentiation phenotypes in lung cancer, and may suggest a hierarchy of progenitor cells and lineage-specific subpopulations within these tumors.

Citation Format: Jacob M. Kaufman, Cindy Lowe, Bradford Harris, Kelli Boyd, Joseph Amann, Rosana Eisenberg, David Carbone, Pierre Massion. Dysregulation of lung developmental pathways associated with LKB1 loss in lung cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2404.

Fluorocoxib A loaded nanoparticles enable targeted visualization of cyclooxygenase-2 in inflammation and cancer

Cyclooxygenase-2 (COX-2) is expressed in virtually all solid tumors and its overexpression is a hallmark of inflammation. Thus, it is a potentially powerful biomarker for the early clinical detection of inflammatory disease and human cancers. We report a reactive oxygen species (ROS) responsive micellar nanoparticle, PPS-b-POEGA, that solubilizes the first fluorescent COX-2-selective inhibitor fluorocoxib A (FA) for COX-2 visualization in vivo. Pharmacokinetics and biodistribution of FA-PPS-b-POEGA nanoparticles (FA-NPs) were assessed after a fully-aqueous intravenous (i.v.) administration in wild-type mice and revealed 4-8 h post-injection as an optimal fluorescent imaging window. Carrageenan-induced inflammation in the rat and mouse footpads and 1483 HNSCC tumor xenografts were successfully visualized by FA-NPs with fluorescence up to 10-fold higher than that of normal tissues. The targeted binding of the FA cargo was blocked by pretreatment with the COX-2 inhibitor indomethacin, confirming COX-2-specific binding and local retention of FA at pathological sites. Our collective data indicate that FA-NPs are the first i.v.-ready FA formulation, provide high signal-to-noise in inflamed, premalignant, and malignant tissues, and will uniquely enable clinical translation of the poorly water-soluble FA compound.

A phase II study of capecitabine and oxaliplatin combination chemotherapy in patients with inoperable adenocarcinoma of the gall bladder or biliary tract

BACKGROUND

Advanced biliary tract carcinomas are associated with a poor prognosis, and palliative chemotherapy has only modest benefit. This multi-centre phase II study was conducted to determine the efficacy of capecitabine in combination with oxaliplatin in patients with inoperable gall bladder or biliary tract cancer.

METHODS

This was a Phase II, non-randomised, two-stage Simon design, multi-centre study. Ethics approval was sought and obtained by the North West MREC, and then locally by the West Glasgow Hospitals Research Ethics Committee. Eligible patients with inoperable locally advanced or metastatic adenocarcinoma of the gall bladder or biliary tract and with adequate performance status, haematologic, renal, and hepatic function were treated with capecitabine (1000 mg/m(2) po, twice daily, days 1-14) and oxaliplatin (130 mg/m(2) i.v., day 1) every 3 weeks for up to six cycles. The primary objective of the study was to determine the objective tumour response rates (complete and partial). The secondary objectives included assessment of toxicity, progression-free survival, and overall survival.

RESULTS

Forty-three patients were recruited between July 2003 and December 2005. The regimen was well tolerated with no grade 3/4 neutropenia or thrombocytopenia. Grade 3/4 sensory neuropathy was observed in six patients. Two-thirds of patients received their chemotherapy without any dose delays. Overall response rate was 23.8% (95% CI 12.05-39.5%). Stable disease was observed in a further 13 patients (31%) and progressive disease observed in 12 (28.6%) of patients. The median progression-free survival was 4.6 months (95% CI 2.8-6.4 months; Fig. 1) and the median overall survival 7.9 months (95% CI 5.3-10.4 months; Fig. 2). Fig. 1 Progression-free survival Fig. 2 Overall survival

CONCLUSION

Capecitabine combined with oxaliplatin has a lower disease control and shorter overall survival than the combination of cisplatin with gemcitabine which has subsequently become the standard of care in this disease. However, capecitabine in combination with oxaliplatin does have modest activity in this disease, and can be considered as an alternative treatment option for patients in whom cisplatin and/or gemcitabine are contra-indicated.

Effects of Repeated Anesthesia Containing Urethane on Tumor Formation and Health Scores in Male C57BL/6J Mice

Repeated injection of urethane (ethyl carbamate) is carcinogenic in susceptible strains of mice. Most recent cancer studies involving urethane-induced tumor formation use p53(+/-) mice, which lack one copy of the p53 tumor suppressor gene. In contrast, the same protocol elicits at most a single tumor in wildtype C57BL/6 mice. The effect of repeatedly injecting urethane as a component of a ketamine-xylazine anesthetic mixture in the highly prevalent mouse strain C57BL/6 is unknown. Male C57BL/6J mice (n = 30; age, 3 mo) were anesthetized once monthly for 4 mo by using 560 mg/kg urethane, 28 mg/kg ketamine, and 5.6 mg/kg xylazine. The physical health of the mice was evaluated according to 2 published scoring systems. The average body condition score (scale, 1 to 5; normal, 3) was 3.3, 3.3, and 3.4 after the 2nd, 3rd, and 4th injections, respectively. The visual assessment score was 0 (that is, normal) at all time points examined. Within 1 wk after the 4th injection, the mice were euthanized, necropsied, and evaluated histopathologically. No histopathologic findings were noteworthy. We conclude that repeated monthly injection with urethane as a component of an anesthetic cocktail does not cause clinically detectable abnormalities or induce neoplasia in C57BL/6J mice. These findings are important because urethane combined with low-dose ketamine, unlike other anesthetic regimens, allows for accurate recording of neuronal activity in both the brain and retina. Longitudinal neuronal recordings minimize the number of mice needed and improve the analysis of disease progression and potential therapeutic interventions.

Socioeconomic status, human papillomavirus, and overall survival in head and neck squamous cell carcinomas in Toronto, Canada

BACKGROUND

Despite universal healthcare in some countries, lower socioeconomic status (SES) has been associated with worse cancer survival. The influence of SES on head and neck cancer (HNC) survival is of immense interest, since SES is associated with the risk and prognostic factors associated with this disease.

PATIENTS AND METHODS

Newly diagnosed HNC patients from 2003 to 2010 (n=2124) were identified at Toronto's Princess Margaret Cancer Centre. Principal component analysis was used to calculate a composite score using neighbourhood-level SES variables obtained from the 2006 Canada Census. Associations of SES with overall survival were evaluated in HNC subsets and by p16 status (surrogate for human papillomavirus).

RESULTS

SES score was higher for oral cavity (n=423) and p16-positive oropharyngeal cancer (OPC, n=404) patients compared with other disease sites. Lower SES was associated with worse survival [HR 1.14 (1.06-1.22), p=0.0002], larger tumor staging (p<0.001), current smoking (p<0.0001), heavier alcohol consumption (p<0.0001), and greater comorbidity (p<0.0002), but not with treatment regimen (p>0.20). After adjusting for age, sex, and stage, the lowest SES quintile was associated with the worst survival only for OPC patients [HR 1.66 (1.09-2.53), n=832], primarily in the p16-negative subset [HR 1.63 (0.96-2.79)]. The predictive ability of the prognostic models improved when smoking/alcohol was added to the model (c-index 0.71 vs. 0.69), but addition of SES did not (c-index 0.69).

CONCLUSION

SES was associated with survival, but this effect was lost after accounting for other factors (age, sex, TNM stage, smoking/alcohol). Lower SES was associated with greater smoking, alcohol consumption, comorbidity, and stage.

PERIPHERAL NERVE BING-NEEL SYNDROME

Background

Bing-Neel syndrome (BNS) is a rare manifestation of Waldenstrom's Macroglobulinaemia (WM) due to direct infiltration of the central nervous system. Isolated peripheral nerve infiltration has not been described but as the blood-nerve-barrier has similar characteristics to the blood-brain-barrier, CNS-penetrating chemotherapy would be required.

Case

A 43 year-old man was diagnosed with WM after presenting with constitutional symptoms; IgMk paraprotein (34.6 g/L) and lymphoplasmacytoid cells in the bone marrow. He received R-CVP (Rituximab, Cyclophosphamide, Vincristine, and Prednisolone) with good partial haematological response and minimal distal sensory vincristine-related neuropathy. Ten months later he developed a rapidly progressive, symmetric sensorimotor deficit in all four limbs with impairment of walking and hand clumsiness, MRC sum score=61/70. Electrophysiology showed a non-length dependant axonal neuropathy with patchy slowing. Sural nerve biopsy revealed a patchy infiltrate WM cells. He tolerated 4 cycles of blood-nerve-barrier penetrating multi-agent chemotherapy, IDARAM (idarubicin, dexamethasone, cytosine arabinoside, methotrexate, cytosine arabinoside plus intrathecal methotrexate). A marked improvement was seen during treatment and by 3 months later MRC score was 70/70. No electrophysiological difference was detectable at this stage.

Discussion

Peripheral BNS is not a recognised neurological manifestation of WM but with appropriate treatment a good outcome may be achieved.

Border patrol gone awry: lung NKT cell activation by F. tularensis exacerbates tularemia-like disease (MUC1P.908)

The respiratory mucosa is a major site for pathogen invasion and, hence, a site requiring constant immune surveillance. The semi-invariant natural killer T (NKT) cells are enriched within the lung vasculature. Despite optimal positioning for border patrol, the role of NKT cells in respiratory infectious diseases remains poorly understood. Hence, we assessed their function in a murine model of pulmonary tularemia—because tularemia is a sepsis-like proinflammatory disease and NKT cells are known to control the cellular and humoral responses underlying sepsis. Here we show for the first time that respiratory infection with Francisella tularensis live vaccine strain results in rapid recruitment of NKT cells to the lung interstitium. Interstitial NKT cell activation resulted in protective interferon-γ production, and affected both local and systemic proinflammatory responses. Hence, NKT cell-deficient mice showed reduced inflammatory cytokine and chemokine response yet survived the infection whilst their wild type counterparts did not. Strikingly, NKT cell-deficient mice had increased lymphocytic infiltration in the lungs that organized into structures resembling induced bronchus-associated lymphoid tissue (iBALT) at the peak of infection. Thus, NKT cell activation by F tularensis infection hampers iBALT formation, which in conjunction with NKT cell-dependent proinflammatory response causes severe pulmonary tularemia-like disease in mice.

The effects of glucuronic acid and N-acetyl-D-glucosamine on in vitro fertilisation of porcine oocytes

High incidences of polyspermic penetration continue to challenge researchers during porcine in vitro fertilisation (IVF). The aim of this study was to reduce the incidence of polyspermy by increasing the perivitelline space thickness with glucuronic acid and N-acetyl-D-glucosamine (GlcNAc) supplementation during oocyte maturation. After maturation, zona pellucida and perivitelline space thicknesses, intracellular glutathione concentrations and fertilisation kinetics were measured, in addition to embryonic cleavage and blastocyst formation at 48h and 144h after IVF, respectively. There were no significant differences between the treatments for zona pellucida thickness, penetration rates, male pronuclear formation or cortical granule exocytosis. Glucuronic acid supplementation significantly increased (PPPP<0.05) of cleavage and blastocyst formation by 48 and 144h after IVF compared with all other groups. These results indicate that supplementing with 0.005mM glucuronic acid and 0.005mM GlcNAc during oocyte maturation decreases the incidence of polyspermic penetration by increasing perivitelline space thickness and improving embryo development in pigs.