Achievement of Target Gain Larger than Unity in an Inertial Fusion Experiment

On December 5, 2022, an indirect drive fusion implosion on the National Ignition Facility (NIF) achieved a target gain G_{target} of 1.5. This is the first laboratory demonstration of exceeding "scientific breakeven" (or G_{target}>1) where 2.05 MJ of 351 nm laser light produced 3.1 MJ of total fusion yield, a result which significantly exceeds the Lawson criterion for fusion ignition as reported in a previous NIF implosion [H. Abu-Shawareb et al. (Indirect Drive ICF Collaboration), Phys. Rev. Lett. 129, 075001 (2022)PRLTAO0031-900710.1103/PhysRevLett.129.075001]. This achievement is the culmination of more than five decades of research and gives proof that laboratory fusion, based on fundamental physics principles, is possible. This Letter reports on the target, laser, design, and experimental advancements that led to this result.

Bioanalysis of the Bicycle® toxin conjugate BT5528 and released monomethyl auristatin E via liquid chromatography-tandem mass spectrometry

Background: The Bicycle® toxin conjugate BT5528 is a novel peptide therapeutic conjugated to the cytotoxic agent monomethyl auristatin E (MMAE). A bioanalytical assay was developed to quantify BT5528 and unconjugated MMAE in human plasma. Methodology: BT5528 quantitation used a protein precipitation procedure followed by LC-MS/MS detection. Quantitation of MMAE required a selective offline and online solid-phase extraction with detection via LC-MS/MS. Results: BT5528 was quantified over the assay range of 5-2500 ng/ml and free MMAE was quantified over the assay range of 0.05-50 ng/ml. Conclusion: Bioanalytical methods were used in the bioanalysis of intact BT5528 and released MMAE, in a phase I/IIa clinical trial; to date, over 2000 human patient samples have been analyzed.

Comparison of Meal Patterns Across Common Racial Groups in the UK and the USA, Examining Associations with Weight Status and Diet Quality: a Secondary Analysis of NDNS and NHANES Datasets

OBJECTIVE

Understanding diets of population subgroups is essential for monitoring health of diversifying populations, but currently, meal patterns of many population subgroups are not widely known. This paper aimed to identify meal patterns of racial groups in the UK and USA, considering if racial groups exhibit similar patterns of intake irrespective of location and relationships between meal patterns and health parameters.

DESIGN

Data were extracted from the UK (National Diet and Nutrition Survey) and the USA (National Health and Nutrition Examination Survey) national dietary surveys. Temporal and content meal patterns among racial groups in the UK and USA (White, Black, Asian and Other, n = 1780 and n = 4339, respectively) were examined. Kruskal-Wallis tests were applied to understand differences across groups. Logistic regression models identified associations between meal patterns and body mass index and diet quality.

RESULTS

Black groups consumed fewer eating occasions than White and Other groups in both countries, while UK racial groups consumed significantly more snacks than USA groups. Food group contribution to eating occasion consumption was similar across countries where Asian groups in the USA and UK had the lowest meat intake at lunch and dinner. Meal frequency was positively associated with diet quality.

CONCLUSIONS

Overall, meal patterns differ across racial groups within a single country, and some differences were observed within groups of the same race across countries. Learnings from this research highlight the differences in consumption patterns across racial groups and the importance of considering a meal-based approach to dietary guidelines by racial group.

Supervised physical activity and the incidence of gestational diabetes mellitus: a systematic review and meta-analysis

BACKGROUND

Gestational diabetes mellitus (GDM) characterized by dysfunction in maintaining glucose homeostasis is recognized as the most common metabolic complication associated with pregnancy leading to adverse clinical outcomes for maternal and fetal health. Although previous analysis of the findings from randomized controlled trials (RCTs) support that regular physical activity reduces the incidence of GDM during pregnancy, less is known about the optimal timing of intervention with respect to trimester stage.

OBJECTIVES

To examine the interaction between both the timing and volume of supervised physical activity interventions on reducing the incidence of GDM during pregnancy.

STUDY DESIGN

Electronic databases including CINAHL, Embase, Medline and the Cochrane library were searched for records up to 29 September 2022. Eligibility criteria were RCTs including standard antenatal care + supervised physical activity intervention without dietary modification vs. those receiving standard antenatal care alone in women with no previous diagnosis of GDM, type 1 or type 2 diabetes mellitus.

RESULTS

Of the 3411 records identified, 20 RCTs comprising 6732 participants were included. It was found that supervised physical activity interventions decreased GDM risk when started within the first trimester (RR: 0.57, 95% CI: 0.41-0.79; p = .001) and by accumulating >600 MET·min·wk^-1 of exercise (RR: 0.77, 95% CI: 0.60-0.98; p = .03) compared with standard antenatal care alone. Women with a BMI ≤25 kg/m² experienced the greatest risk reduction in GDM following supervised exercise training (RR: 0.51, 95% CI: 0.34-0.75; p = .001).

CONCLUSION

Supervised physical activity reduces the incidence of GDM during pregnancy. It is recommended that pregnant individuals achieve a minimum of 600 MET·min·wk^-1 of physical activity during the first trimester in order to reduce their odds of developing GDM. Attaining a healthy pre-pregnancy BMI is also an important determinant for the prevention of GDM with exercise.

BT8009; A Nectin-4 Targeting Bicycle Toxin Conjugate for Treatment of Solid Tumors

Multiple tumor types overexpress Nectin-4 and the antibody-drug conjugate (ADC), enfortumab vedotin (EV) shows striking efficacy in clinical trials for metastatic urothelial cancer, which expresses high levels of Nectin-4, validating Nectin-4 as a clinical target for toxin delivery in this indication. Despite excellent data in urothelial cancer, little efficacy data are reported for EV in other Nectin-4 expressing tumors and EV therapy can produce significant toxicities in many patients, frequently leading to discontinuation of treatment. Thus, additional approaches to this target with the potential to extend utility and reduce toxicity are warranted. We describe the preclinical development of BT8009, a "Bicycle Toxin Conjugate" (BTC) consisting of a Nectin-4-binding bicyclic peptide, a cleavable linker system and the cell penetrant toxin mono-methylauristatin E (MMAE). BT8009 shows significant antitumor activity in preclinical tumor models, across a variety of cancer indications and is well tolerated in preclinical safety studies. In several models, it shows superior or equivalent antitumor activity to an EV analog. As a small hydrophilic peptide-based drug BT8009 rapidly diffuses from the systemic circulation, through tissues to penetrate the tumor and target tumor cells. It is renally eliminated from the circulation, with a half-life of 1-2 hours in rat and non-human primate. These physical and PK characteristics differentiate BT8009 from ADCs and may provide benefit in terms of tumor penetration and reduced systemic exposure. BT8009 is currently in a Phase 1/2 multicenter clinical trial across the US, Canada, and Europe, enrolling patients with advanced solid tumors associated with Nectin-4 expression.

Lawson Criterion for Ignition Exceeded in an Inertial Fusion Experiment

For more than half a century, researchers around the world have been engaged in attempts to achieve fusion ignition as a proof of principle of various fusion concepts. Following the Lawson criterion, an ignited plasma is one where the fusion heating power is high enough to overcome all the physical processes that cool the fusion plasma, creating a positive thermodynamic feedback loop with rapidly increasing temperature. In inertially confined fusion, ignition is a state where the fusion plasma can begin "burn propagation" into surrounding cold fuel, enabling the possibility of high energy gain. While "scientific breakeven" (i.e., unity target gain) has not yet been achieved (here target gain is 0.72, 1.37 MJ of fusion for 1.92 MJ of laser energy), this Letter reports the first controlled fusion experiment, using laser indirect drive, on the National Ignition Facility to produce capsule gain (here 5.8) and reach ignition by nine different formulations of the Lawson criterion.

Abstract 333: Activity of the erythropoietin-producing hepatocellular A2 receptor (EphA2) targeting Bicycle® Toxin Conjugate (BTC™) BCY6033 in EGFR inhibitor resistant non-small lung cancer (NSCLC) patient derived xenografts

Introduction: EphA2 regulates cell migration, adhesion, proliferation and differentiation, and is overexpressed in human cancers which have been shown to correlate with tumor progression. BCY6033 contains a bicyclic peptide targeting EphA2, linked to the cytotoxin Monomethyl auristatin E via a molecular spacer and cleavable linker designed to target EphA2 expressing tumors. BCY6033 is analogous to BT5528, a BTC™ currently in phase I/II clinical trial in patients with advanced malignancies associated with EphA2 expression. Recent literature indicate that tumor EphA2 expression may be up regulated in EGFR mutant lung models following 1st, 2nd and possibly 3rd generation EGFR inhibitors. Here we report on EphA2 expression in well characterized and clinically annotated patient derived xenografts (PDX) of NSCLC including EGFR mutant NSCLC derived either from erlotinib or osimertinib resistant patients. In vivo activity of BCY6033 is presented in two EphA2 expressing PDX models.

Experimental procedures: In vivo, an initial tolerability study was conducted with once weekly administration of BCY6033 by intravenous injection in NSG mice. The activity of BCY6033 was evaluated in EphA2 expressing EGFR mutant PDX models, DFCI-161 and DFCI-220 in NSG mice. A TMA was constructed containing FFPE derived from 69 PDX models (NSCLC n=61, SCLC-transformed n=5, de novo SCLC n=3). Of the 69 models, 35 were EGFR mutant. The TMA was subsequently stained via immunohistochemistry (IHC) using an α-EphA2 (R&D Systems) primary antibody. Tumor membranous H-score was assigned by a pathologist and a score of ≥50 was considered positive.

Results: Of the 69 PDXs, 16 were determined to be EphA2 positive. No correlation with genotype or clinical history was observed with EphA2 expression. EphA2 IHC was repeated on at least 5 different tumors for 5 PDX models with fast and robust in vivo growth latency. Two models, DFCI-161 and DFCI-220 with the most reproducible EphA2 staining were selected. Treatment with BCY6033 showed that a dose of 3 mg/kg once weekly administered intravenously was well tolerated in female NSG mice. BCY6033 treatment led to significant tumor growth inhibition with >80% tumor regressions in both DFCI-161 and DFCI-220 PDX models. Re-challenge of tumor out-growth showed that they retain sensitivity to BCY6033 treatment.

Conclusion: BCY6033 is a potentially promising drug effective against EphA2 expressing PDX models. Future studies and clinical trials will seek to determine the efficacy of BT5528 in EphA2 expressing tumors.

Citation Format: Kenneth Ngo, Elena V. Ivanova, Tyler J. Teceno, Carly Campbell, Johanna Lahdenranta, Stephen J. Blakemore, Gavin Bennett, Pasi A. Jänne, Cloud P. Paweletz, Prafulla C. Gokhale. Activity of the erythropoietin-producing hepatocellular A2 receptor (EphA2) targeting Bicycle® Toxin Conjugate (BTC™) BCY6033 in EGFR inhibitor resistant non-small lung cancer (NSCLC) patient derived xenografts [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 333.

Abstract 1319: Rapid accumulation of cytotoxic payload in tumor tissue drives BT5528 activity in tumor models

BT5528 was developed as a Bicycle® toxin conjugate to deliver monomethyl auristatin E (MMAE) -payload to EphA2 overexpressing tumors. It consists of a bicyclic peptide targeting the tumor antigen EphA2, linked to the cytotoxin MMAE via a molecular spacer and cleavable linker. Administration of BT5528 results in rapid uptake of payload into EphA2 overexpressing xenograft tumors associated with persistent toxin levels in tumor tissue and limited systemic exposure of both parent drug and payload (1). BT5528 showed a favorable preclinical profile supporting the initiation of a first-in-human Phase I/II study (NCT04180371) to investigate safety and efficacy of BT5528 in indications with evidence of EphA2 expression including non-small-cell lung cancer (NSCLC), ovarian cancer, triple-negative breast cancer (TNBC), gastric/upper gastrointestinal (GI), pancreatic and urothelial cancers (2). We have used EphA2 overexpressing tumor xenograft models in both mice and rats to elucidate the relative differences between toxin payload delivery and systemic exposure of BT5528. Comparison of payload-delivery and systemic exposure from EphA2 -targeted Bicycle toxin conjugate and antibody-drug conjugate (ADC) demonstrate the differentiation of these toxin-payload delivery platforms. ADC payload delivery depends upon a sustained plateau-like pharmacokinetic (PK) profile that exposes target and potentially nontarget organs to intact ADC for several days. In contrast, BT5528 achieves prolonged toxin delivery to tumors, following transient exposure in plasma of less than one hour. A Phase I/II study of BT5528 in patients with solid tumors is ongoing, which will investigate if this PK novel, differentiated pharmacokinetic profile, unique to Bicycle toxin conjugates, gives rise to a favorable balance of efficacy and safety. References: 1. Bennett et al. Mol. Cancer Ther. 2020;19:1385-942. 2. Bendell et al. TPS3655 Journal of Clinical Oncology 38, no. 15_suppl

Citation Format: Johanna Lahdenranta, Gavin Bennett, Philip Huxley, Gemma Mudd, Punit Upadhyaya, Phil Jeffrey, Nicholas Keen. Rapid accumulation of cytotoxic payload in tumor tissue drives BT5528 activity in tumor models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1319.

60 Front Door Specialist Frailty MDT Working at MFT NHS Trust—The Therapy Team Poster Presentation

Introduction

The therapy team consists of physiotherapists, Occupational therapists and therapy technicians working generically to deliver a comprehensive therapy assessment to patients presenting in our Emergency Department, Clinical Decisions Unit and Medical Admissions Unit between the hours of 08:00–18:00 7 days a week. The therapists provide the hospitals frailty service in ED and MAU with early therapy assessment and intervention, supporting the provision of a Comprehensive Geriatric Assessment. The aims of our service are to provide early therapy assessment of our most vulnerable patients to avoid unnecessary hospital admissions and reduce readmission rates, and for those requiring hospital care to provide early mobilisation and discharge planning to reduce length of stay and complications associated with hospital admission. We provide the therapy component of the CGA as part of the specialist frailty MDT service and act as an interface with local community health and social services.

Method

A full review of our frailty MDT service was undertaken and a re-allocation of our resources and staff was piloted in July 2019.

During this pilot our therapy staff presence was re-distributed allowing greater patient numbers to be assessed promptly on their arrival to ED.

This adjustment supported the Frailty MDT actions of:

Results

Data collection showed total referrals to therapy increased from 67 (June 2019) to 160 (July 2019). In July same day discharges were at 43%; discharges ≥72 hours 24%; 7 day readmission at 9%; 28 day readmissions at 11% and 38% were referred to community services.

Conclusion

These changes enabled us to provide a full MDT frailty service to frail older people presenting at our ED in a timely manner and to a larger number of suitable patients.

BT5528-100 phase I/II study of the safety, pharmacokinetics, and preliminary clinical activity of BT5528 in patients with advanced malignancies associated with EphA2 expression

TPS3655

Background: BT5528 is a Bicycle Toxin Conjugate (BTC), comprising a bicyclic peptide targeting the tumor antigen EphA2, linked to a cytotoxin (monomethyl auristatin E [MMAE]) via a tumor microenvironment cleavable linker. Bicycles are a novel class of chemically synthesized constrained peptides, developed by Bicycle Therapeutics. EphA2 is reported to be overexpressed in a range of solid tumors, contributes to oncogenesis, tumor-associated angiogenesis and metastasis. Intracellular EphA2 signaling converges on pathways that are integral to cell growth, proliferation, migration and invasion. Increased EphA2 expression has been identified as a resistance mechanism to EGFR Tyrosine Kinase Inhibitor based therapy. BT5528 mechanism of action is dependent on tumor penetration, target binding and release of MMAE toxin payload. BTCs offer advantages over antibody-toxin conjugates exhibiting rapid penetration of dense tumors and decreased extra-tumor exposure. BT5528 exhibited a favorable preclinical profile supporting the initiation of a first-in-human study to investigate safety and efficacy of BT5528 in indications with evidence of EphA2 expression including non-small-cell lung cancer (NSCLC), ovarian cancer, triple-negative breast cancer (TNBC), gastric/upper gastrointestinal (GI), pancreatic and urothelial cancers. Methods: BT5528-100 (NCT04180371) is a Ph I/II study to evaluate safety and tolerability of weekly BT5528 alone and in combination with Q4W nivolumab. Each dose escalation utilizes a 3+3 design which converts to a Bayesian design to determine MTD or MAD and RP2D for BT5528 with and without nivolumab. Eligible patients must have advanced solid tumors associated with EphA2 expression which have recurred after exhausting standard treatment options. Patients must have available tumor tissue and acceptable hematologic and organ function, with exclusions for uncontrolled brain metastases, thromboembolic events, bleeding disorders, uncontrolled hypertension, CYP3A4 inhibitors/inducers or, for the nivolumab cohorts, autoimmune disease. On-study tumor and blood samples will be collected for biomarker evaluations including tumor EphA2 expression, ADA, and candidate response biomarkers for BT5528 alone and combination with nivolumab. Pharmacokinetic data will be reported for C1D1 and D15 for BT5528 and MMAE. The expansion phase will enroll specific tumor types to evaluate clinical activity of BT5528. Enrollment is ongoing. Clinical trial information: NCT04180371 .

MMAE Delivery Using the Bicycle Toxin Conjugate BT5528

The EphA2 receptor is found at high levels in tumors and low levels in normal tissue and high EphA2 expression in biopsies is a predictor of poor outcome in patients. Drug discovery groups have therefore sought to develop EphA2-based therapies using small molecule, peptide, and nanoparticle-based approaches (1-3). However, until now only EphA2-targeting antibody-drug conjugates (ADC) have entered clinical development. For example, MEDI-547 is an EphA2-targeting ADC that displayed encouraging antitumor activity in preclinical models and progressed to phase I clinical testing in man. Here we describe the development of BT5528, a bicyclic peptide ("Bicycle") conjugated to the auristatin derivative maleimidocaproyl-monomethyl auristatin E to generate the Bicycle toxin conjugate BT5528. The report compares and contrasts the Pharmacokinetics (PK) characteristics of antibody and Bicycle-based targeting systems and discusses how the PK and payload characteristics of different delivery systems impact the efficacy-toxicity trade off which is key to the development of successful cancer therapies. We show that BT5528 gives rise to rapid update into tumors and fast renal elimination followed by persistent toxin levels in tumors without prolonged exposure of parent drug in the vasculature. This fast in, fast out kinetics gave rise to more favorable toxicology findings in rats and monkeys than were observed with MEDI-547 in preclinical and clinical studies.Graphical Abstract: http://mct.aacrjournals.org/content/molcanther/19/7/1385/F1.large.jpg.

Gas Chromatographic Determination of Deoxynivalenol in Wheat with Electron Capture Detection: Collaborative Study

Ten laboratories participated in a collaborative study of a method for the determination of deoxynivalenol in wheat by gas chromatography with electron capture detection. Each laboratory analyzed 6 samples in duplicate. Each collaborator received samples spiked at the 100.3, 501.3, and 1002.6 ng/g levels; a control sample; and 2 naturally contaminated samples. The average recovery (outliers excluded) for the spiked samples was 92.2%. The mean repeatability and reproducibility, respectively, were 32.2 and 41.3% for the spiked samples and 30.9 and 47.6% for the naturally contaminated samples. The method was adopted official first action.

Abstract 4479: BT8009: A bicyclic peptide toxin conjugate targeting Nectin-4 (PVRL4) displays efficacy in preclinical tumor models

We have identified a Nectin-4 targeting peptide for delivery of cytotoxic agents to Nectin-4 expressing tumors. Nectin-4 is a cell adhesion molecule, that is highly expressed in certain tumor types, including bladder, TNBC and NSCLC, but has a restricted distribution in normal tissue. Bicycles® are small (1.5kDa) fully synthetic, structurally constrained, peptide drugs that combine the affinity of antibodies with the pharmacokinetic properties of small molecules. The Bicycle phage display platform was utilised to rapidly identify a high affinity (18 nM) and highly selective bicyclic Nectin-4 binding peptide. Synthetic modification of the initial lead peptide improved affinity (0.3 nM), hydrophilicity and stability. The optimised peptide is conjugated through an inert sarcosine spacer chain and a cleavable linker to the toxin MMAE, to form the Bicycle Toxin Conjugate (BTC) BT8009. Once bound to cell surface Nectin-4, the linker system is cleaved by peptidases (e.g. cathepsin B) upregulated in the tumor micro environment. Full structure of BT8009 will be disclosed within the presentation. Fluorescence polarisation and surface plasmon resonance show BT8009 has low nanomolar affinity (3nM) for Nectin-4 and high selectivity (>1000 fold) over Nectins 1-3, and the 5 nectin-like, family members. Good affinity for the cognate native protein is maintained across the preclinical safety species. High content imaging of cultures of MDA-MB-468 cells, demonstrates binding of the BTC to cell membrane. In vivo, BT8009 is well tolerated in mouse and rat and shows regressions across a range of cell and patient derived xenograft models. Efficacy correlates with the expression level of Nectin-4 on the tumor cells, and the dose delivered. In the MDA-MB-468 (TNBC) CDX model full tumor regression was seen with weekly i.v. administration of 3 mg/k g i.v. (4 doses), with no tumor regrowth out to 70 days post last dose. Similar efficacy was seen in two NSCLC PDX models (adenocarcinoma and squamous cell carcinoma) with full regression attained in both. Near full regression was seen in a squamous cell esophageal cancer PDX. Larger tumors show a similar degree of sensitivity to the BTC, with rapid tumor regression from a volume of 800 mm3. As a small peptide BT8009 undergoes rapid clearance from the plasma with minimal exposure to non-targeted organs. After a single dose, MMAE has been shown to be retained within tumor tissue in excess of 60 h, at exposure levels significantly greater than corresponding plasma and other tissue levels. Bicycle Toxin Conjugates represent a novel treatment modality for nectin-4 expressing tumors with excellent efficacy in several mouse xenograft models.

Citation Format: Mike Rigby, Paul Beswick, Gemma Mudd, Katerine Van Rietschoten, Liuhong Chen, Sophie M. Watcham, Heather Allen, Amy Brown, Helen Harrison, Gavin Bennett, Phil Jeffrey, Peter U. Park, Maria Koehler, Nicholas Keen. BT8009: A bicyclic peptide toxin conjugate targeting Nectin-4 (PVRL4) displays efficacy in preclinical tumor models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4479.

Abstract 3257: Activation of CD137 using multivalent and tumor targeted Bicyclic peptides

CD137 (4-1BB/TNFRSF9) is a costimulatory T-cell receptor belonging to the TNF receptor superfamily. Agonistic anti-CD137 antibodies have shown potent, often curative anti-tumor activity in preclinical models. Two human anti-CD137 antibodies, urelumab and utomilumab are currently undergoing clinical testing. Urelumab has shown several single-agent, partial responses, but its use has been hampered by hepatoxicity, while utomilumab has shown little or no single agent activity.

Bicycles® are a new class of drugs - fully synthetic, constrained bicyclic peptides that combine the attributes of antibodies, small molecules, and peptides by delivering high affinity, selectivity, and rapid clearance. Their small size (1.5-2 kDa) delivers advantages in tumor penetration, and renal elimination may avoid the liver and GI toxicity often associated with other drug modalities, including certain antibodies. We hypothesized that fully synthetic Bicycle CD137 agonists with rapid clearance, minimal liver exposure and no Fc receptor interaction may induce CD137 mediated anti-tumor activity while avoiding liver toxicity.

A high affinity lead BCY3814 (KD ~30 nM) that binds to the CD137 ligand-binding site was identified. CD137 activation requires receptor crosslinking, thus multivalent binding would be expected to recapitulate the action of the natural trimeric ligand. We envisioned that CD137 agonism could be achieved directly by using multimeric CD137 Bicycles or in a tumor targeted fashion with bispecific or “heterotandem” Bicycles. The synthetic simplicity and highly modular nature of the Bicycle® platform enabled us to rapidly explore both formats.

To generate a “pure” CD137 agonist we synthesized >50 different multimeric variants of BCY3814 with chemical linkers of various lengths and rigidity and using different sites of attachments, while maintaining a compact size (<15 kDa). Tumor targeted CD137 agonists were generated as heterotandems, whereby BCY3814 is conjugated to a tumor antigen targeting Bicycle. In this design, the CD137 Bicycle only induces CD137 agonism after the molecule binds to a tumor cell with high receptor expression.

We discovered Bicycle multimers that exhibit a range of potencies in a cell-based CD137-dependent reporter assay, activate human T cells in vitro as indicated by increased cytokine release, and show biological activity in vivo. Bicycle heterotandems targeting Nectin-4 and EphA2 exhibited highly potent and tumor cell specific activity in both the cell-based reporter assay and the human T cell assay. Selected CD137 multimers and heterotandems are being tested further in humanized mouse models for T cell activation, anti-tumor activity, and liver safety. These molecules are promising, novel cancer immunotherapy candidates and importantly, they pave the way for development of synthetic agonists of other TNF receptors that can be targeted to the local tumor microenvironment.

Citation Format: Kristen E. Hurov, Punit Upadhyaya, Jessica Kublin, Xueyuan Zhou, Julia Kristensson, Rachid Lani, Gemma Mudd, Katerine van Rietschoten, Frank An, Johanna Lahdenranta, Liuhong Chen, Gavin Bennett, Kevin McDonnell, Peter Park, Nicholas Keen. Activation of CD137 using multivalent and tumor targeted Bicyclic peptides [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3257.

Investigation of Fugitive Aerosols Released into the Environment during High-Flow Therapy

BACKGROUND

Nebulised medical aerosols are designed to deliver drugs to the lungs to aid in the treatment of respiratory diseases. However, an unintended consequence is the potential for fugitive emissions during patient treatment, which may pose a risk factor in both clinical and homecare settings.

METHODS

The current study examined the potential for fugitive emissions, using albuterol sulphate as a tracer aerosol during high-flow therapy. A nasal cannula was connected to a head model or alternatively, a interface was connected to a tracheostomy tube in combination with a simulated adult and paediatric breathing profile. Two aerodynamic particle sizers (APS) recorded time-series aerosol concentrations and size distributions at two different distances relative to the simulated patient.

RESULTS

The results showed that the quantity and characteristics of the fugitive emissions were influenced by the interface type, patient type and supplemental gas-flow rate. There was a trend in the adult scenarios; as the flow rate increased, the fugitive emissions and the mass median aerodynamic diameter (MMAD) of the aerosol both decreased. The fugitive emissions were comparable when using the adult breathing profiles for the nasal cannula and tracheostomy interfaces; however, there was a noticeable distinction between the two interfaces when compared for the paediatric breathing profiles. The highest recorded aerosol concentration was 0.370 ± 0.046 mg m-3 from the tracheostomy interface during simulated paediatric breathing with a gas-flow rate of 20 L/min. The averaged MMAD across all combinations ranged from 1.248 to 1.793 µm by the APS at a distance of 0.8 m away from the patient interface.

CONCLUSIONS

Overall, the results highlight the potential for secondary inhalation of fugitive emissions released during simulated aerosol treatment with concurrent high-flow therapy. The findings will help in developing policy and best practice for risk mitigation from fugitive emissions.

Comparison of aerosol delivery across combinations of drug delivery interfaces with and without concurrent high-flow nasal therapy

BACKGROUND

Current clinical practice during high-flow nasal therapy (HFNT) involves utilization of a nasal cannula to provide humidification, with a facemask placed over the cannula to deliver aerosol. Few studies have compared aerosol delivery across various delivery interfaces during HFNT. The objective of this study was to address this gap in the literature and evaluate aerosol delivery using two nebulizer types across different drug delivery interfaces, nasal cannula, facemask, and mouthpiece, during simulated adult HFNT.

METHODS

A facemask or mouthpiece and/or a nasal cannula were positioned on an anatomically correct adult head model. The head model was connected to a breathing simulator via a collection filter. Both healthy breathing pattern and distressed breathing patterns were utilized. Aerosol dose was determined by quantifying the mass of drug captured on a filter positioned distal to the trachea.

RESULTS

During simulated healthy breathing, a significantly greater aerosol dose was observed when the vibrating mesh nebulizer (VMN) was integrated with HFNT alone, supplying aerosol and humidified air simultaneously (2.88 ± 0.15%), as opposed to using with a facemask (0.33 ± 0.07%, 1.62 ± 0.46%, and 1.07 ± 0.25% at 0 L/min (LPM), 2LPM, and 6LPM, respectively) or mouthpiece (0.56 ± 0.13%, 2.16 ± 0.06%, and 1.82 ± 0.41% at 0LPM, 2LPM, and 6LPM). In addition, aerosol delivery was also significantly greater when the VMN was integrated into simulated HFNT (2.88 ± 0.15%), in comparison with using the jet nebulizer (JN) with a facemask (0.82 ± 0.16%) or a mouthpiece (0.86 ± 0.11%). During simulated distressed breathing, a significantly greater aerosol dose was observed when the VMN was integrated with HFNT, supplying aerosol and humidified air simultaneously (6.81 ± 0.45%), compared with using a facemask (0.86 ± 0.04%, 2.96 ± 0.26%, and 4.23 ± 0.93% at 0LPM, 2LPM, and 6LPM) or mouthpiece (0.73 ± 0.37%, 0.97 ± 0.20%, and 3.11 ± 0.53% at 0LPM, 2LPM, and 6LPM, respectively). Aerosol delivery was also greater when the VMN was integrated into HFNT (6.81 ± 0.45%), in comparison with using the JN with a facemask (5.72 ± 0.71%) or a mouthpiece (0.69 ± 0.53%). Furthermore, across all drug delivery interfaces, and in line with previous reports, aerosol delivery was greater during simulated distressed breathing, in comparison with simulated healthy adult breathing.

CONCLUSIONS

This article will be of considerable benefit in enhancing the understanding of aerosol delivery during HFNT, an increasingly adopted therapeutic intervention by healthcare professionals.

Investigation of the Quantity of Exhaled Aerosols Released into the Environment during Nebulisation

BACKGROUND

Secondary inhalation of medical aerosols is a significant occupational hazard in both clinical and homecare settings. Exposure to fugitive emissions generated during aerosol therapy increases the risk of the unnecessary inhalation of medication, as well as toxic side effects.

METHODS

This study examines fugitively-emitted aerosol emissions when nebulising albuterol sulphate, as a tracer aerosol, using two commercially available nebulisers in combination with an open or valved facemask or using a mouthpiece with and without a filter on the exhalation port. Each combination was connected to a breathing simulator during simulated adult breathing. The inhaled dose and residual mass were quantified using UV spectrophotometry. Time-varying fugitively-emitted aerosol concentrations and size distributions during nebulisation were recorded using aerodynamic particle sizers at two distances relative to the simulated patient. Different aerosol concentrations and size distributions were observed depending on the interface.

RESULTS

Within each nebuliser, the facemask combination had the highest time-averaged fugitively-emitted aerosol concentration, and values up to 0.072 ± 0.001 mg m-3 were recorded. The placement of a filter on the exhalation port of the mouthpiece yielded the lowest recorded concentrations. The mass median aerodynamic diameter of the fugitively-emitted aerosol was recorded as 0.890 ± 0.044 µm, lower the initially generated medical aerosol in the range of 2⁻5 µm.

CONCLUSIONS

The results highlight the potential secondary inhalation of exhaled aerosols from commercially available nebuliser facemask/mouthpiece combinations. The results will aid in developing approaches to inform policy and best practices for risk mitigation from fugitive emissions.

Abstract 5855: Bicycle Drug Conjugates targeting EphA2 for the treatment of solid tumors: Discovery and selection of BT5528

Ephrin receptor A2 (EphA2) is a member of the Ephrin receptor family of cell-cell junction proteins and is both highly overexpressed in several solid tumors and associated with poor prognosis in patients. Bicycles® are novel therapeutic agents: bicyclic peptides constrained via a chemical scaffold, which confer structural stability leading to high affinity and selectivity usually associated with antibodies. Bicycles can be elaborated to carry payloads to a specific target and their relatively small size (1.5-3 kDa) allows rapid tissue penetration and extravasation. Bicycle binders for EphA2 were identified using a proprietary phage display peptide technology consisting of highly diverse phage libraries of Bicycles. Initial screening identified Bicycle binders with high affinity for EphA2. EphA2 binding Bicycles were conjugated to cytotoxic payload via a cleavable linker to form a Bicycle Toxin Conjugate (BTC) and evaluated for EphA2 dependent cytotoxicity in vitro and in vivo. Efficacy was seen in EphA2-expressing xenograft models, but toxicity was seen at higher doses. These Bicycles were highly plasma protein bound, and relatively lipophilic. Visualization of Bicycle distribution by microPET showed localization to tumor, but with significant distribution to liver. Subsequent screening with a wider range of phage libraries and scaffolds identified Bicycle binders with alternate structures, lower PPB and lipophilicity. Crystal structures of these Bicycles bound to EphA2 enabled rational design to enhance potency and drug-like properties. Visualization of bio-distribution of these optimised Bicycles by microPET showed localization to tumor, with negligible localization to liver and renal clearance. A range of Bicycle Toxin Conjugates were produced by linking bicycle binders to cleavable linkers and toxin payloads. A series of BTCs were developed with DM1 payload, with linkers ranging from uncleavable to unhindered disulfide. Similarly, a series of BTCs were developed with MMAE payload, using uncleavable linker and a variety of cleavable peptidic linkers with different enzyme sensitivity. Binding affinity is maintained to EphA2 protein and cells expressing EphA2. BTC efficacy was evaluated in EphA2-expressing xenograft models, initially the HT-1080 fibrosarcoma model, but also MDA-MB-231 triple-negative breast cancer and NCI-H1975 lung cancer models. Efficacy was seen from 1mg/kg qw and complete regression of tumors from 2 weeks dosing at 2mg/kg qw. No efficacy was seen in xenograft models without EphA2 expression (eg MOLP-8).From >75 BTCs evaluated, BT5528 was chosen as a candidate molecule to progress to in-depth preclinical profiling. The development of Bicycle Toxin Conjugates against EphA2 allows fast and efficient targeting of solid tumors while sparing non-tumor tissues.

Citation Format: Gavin Bennett, Philip Huxley, Amy Brown, Gemma Mudd, Katerine van Rietschoten, Silvia Pavan, Liuhong Chen, Sophie M. Watcham, Peter U. Park, Nicholas Keen. Bicycle Drug Conjugates targeting EphA2 for the treatment of solid tumors: Discovery and selection of BT5528 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5855.

Abstract 3756: Small synthetic, multivalent bicyclic peptides that activate T cell costimulatory protein CD137

CD137 (4-1BB/TNFRSF9) belongs to the TNF receptor superfamily and provides costimulatory signaling for T cells and NK cells. Agonistic anti-CD137 antibodies have shown potent, often curative anti-tumor activity in preclinical models. These effects are mainly mediated by cytotoxic T cells and generate long lasting, memory responses. Two human anti-CD137 antibodies urelumab and utomilumab are currently undergoing clinical testing. Urelumab has shown several single-agent, partial responses, but its use has been hampered by hepatoxicity, whilst utomilumab lacks hepatotoxicity, but it has shown little or no single agent activity.

Bicycles® are a new class of drugs - fully synthetic, constrained bicyclic peptides that have antibody-like, high affinity and exquisite target specificity unachievable with conventional small molecule approaches. The Bicycle platform uses phage display and chemical optimization to rapidly identify and mature binders for affinity and physicochemical properties. Their small size (1.5-2 kDa) delivers advantages in tumor penetration, and rapid renal elimination may avoid the liver and GI toxicity often associated with other drug modalities, including certain antibodies. We hypothesized that a fully synthetic Bicycle CD137 agonist with rapid renal clearance, minimal liver interaction and no Fc receptor interaction may induce CD137 mediated anti-tumor activity while avoiding liver toxicity.

1015 Bicycles were screened on phage against recombinant CD137. After phage and chemical optimization, a high affinity lead BCY3814 (KD ~30 nM) was selected. BCY3814 competes for binding with the CD137 ligand and utomilumab (known to bind to CD137 ligand binding site) but does not compete with urelumab which binds an alternative epitope. In common with many TNF receptors, CD137 activation requires receptor crosslinking, thus multivalent binders would be expected to recapitulate the action of its natural trimeric ligand. Uniquely, the versatility of the Bicycle format allowed us to rapidly generate more than 50 different bi-, tri- and tetra-valent variants of BCY3814 with chemical linkers and hinges of various lengths and rigidity using different sites of attachments, while maintaining a compact size (<15 kDa). We developed molecules exhibiting a wide range of potency and efficacy in cell-based CD137 activation assays. Several of these synthetic Bicycle CD137 agonists were 10-fold more potent than the clinical antibodies or the natural ligand. These potent Bicycles are being tested in a humanized CD137 mouse model to demonstrate anti-tumour activity with reduced liver toxicity. We hypothesise that such molecules will be promising, novel cancer immunotherapy candidates and pave the way for development of synthetic agonists of other TNF receptors.

Citation Format: Peter U. Park, Rachid Lani, Gemma Mudd, Julia Kristensson, Katerine Van Rietschoten, W. Frank An, Gavin Bennett, Kevin McDonnell, Nicholas Keen. Small synthetic, multivalent bicyclic peptides that activate T cell costimulatory protein CD137 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3756.

In Vitro Determination of the Main Effects in the Design of High-Flow Nasal Therapy Systems with Respect to Aerosol Performance

INTRODUCTION

The use of concurrent aerosol delivery during high-flow nasal therapy (HFNT) may be exploited to facilitate the delivery of a variety of prescribed medications for inhalation. Until now, a systematic approach to determine the conditions required to yield an optimal emitted dose has not been reported. The aim of this study was to establish the effects of gas flow rate, input droplet size, and nebulizer position on the amount of aerosol exiting the nasal cannula during HFNT and thus becoming available for inhalation.

METHODS

Testing was completed according to a factorial statistical design of experiments (DOE) approach. Emitted dose was characterized with a vibrating mesh nebulizer (Aerogen Solo, Aerogen Ltd) for an adult model of HFNT at three clinically relevant gas flow rates, using three nebulizers producing varying input droplet sizes and placed at two different nebulizer positions.

RESULTS

Increasing the gas flow rate significantly lowered the emitted dose, with a dose of 7.10% obtained at 10 LPM, 2.67% at 25 LPM, and 1.30% at 40 LPM (p < 0.0001). There was a significant difference in emitted dose between nebulizers with different input droplet sizes, with increasing input droplet size associated with a reduced emitted dose (6.11% with an input droplet size of 3.22 µm, 2.76% with 4.05 µm, and 2.38% with 4.88 µm, p  = 0.0002, Pearson's r = - 0.2871). In addition, the droplet size exiting the nasal cannula interface was lower than that produced by the aerosol generator for all devices under test. Positioning the nebulizer immediately after the humidification chamber yielded a marginally greater emitted dose (3.79%) than when the nebulizer was placed immediately upstream of the nasal cannula (3.39%). Flow rate, input droplet size, and nebulizer position were at the 0.10 level of significance, indicating that all three factors had significant effects on emitted dose. According to the DOE model, flow rate had the greatest influence on emitted dose, followed by input droplet size and then nebulizer position.

CONCLUSION

Our findings indicate that in order to optimize the amount of aerosol exiting the nasal cannula interface during HFNT, it is necessary for gas flow rate to be low and the input droplet size to be small, while the nebulizer should be positioned immediately after the humidification chamber.

FUNDING

Aerogen Limited.