Abstract 759: Preclinical evaluation of a GFRA1 targeted antibody-drug conjugate in breast cancer

Despite recent advances in treatment, breast cancer remains the second-most common cause of cancer death among American women. A greater understanding of the molecular characteristics of individual tumors could ultimately lead to improved treatment options, particularly for subsets of breast cancer patients with unmet needs. Using an unbiased genomics approach to identify membrane-localized tumor associated antigens (TAAs), we have identified a novel breast cancer TAA that can potentially be exploited through antibody-drug conjugate (ADC) therapy. Here, we describe the development of a GFRA1-targeted ADC that demonstrates activity in GFRA1-positive cell lines and PDX tumor models. Work in non-Good Laboratory Practice (GLP) rat toxicology models revealed acceptable toxicity profiles and supports further evaluation of GFRA1-PBD in GFRA1-positive tumors.

Citation Format: Emily E. Bosco, Ronald J. Christie, Rosa Carrasco, Darrin Sabol, Jiping Zha, Karma DaCosta, Lee Brown, Sandrina Phipps, Qun Du, Binyam Bezabeh, Shannon Breen, Cui Chen, Molly Reed, MaryJane Hinrichs, Haihong Zhong, Zhan Xiao, Rakesh Dixit, Ronald Herbst, David A. Tice. Preclinical evaluation of a GFRA1 targeted antibody-drug conjugate in breast cancer [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 759.

[Analysis on the trend of innovation and development in the field of ophthalmology]

Objective: To systematically analyze the innovation and development trend in the field of ophthalmology. Methods: The latest ophthalmology funding program from the National Eye Institute and National Natural Science Foundation of China, and funding project for 2012 to 2016 from the National Institutes of Health, National Natural Science Foundation of China and National key research and development plan of China was collected. Using the comparative analysis method, the major ophthalmology funding areas at home and abroad were analyzed. Papers published in 2012 to 2016 in the field of ophthalmology were collected from the Web of Science Core Collection, among which ESI highly cited papers and hot papers were particularly selected. Using bibliometric methods, the time trend of the number of papers and the citation frequency were analyzed. Using the co-occurrence cluster analysis method, the continued focuses and emerging concerns of ophthalmology papers was analyzed. Results: The funding plan of the National Eye Institute mainly covers nine major diseases in ophthalmology. NSFC focuses on retinal damage and repair mechanisms. The National Key Research and Development Program of China focuses on research on high-end ophthalmic implants. NIH continues to focus on the molecular mechanisms of blinding eye disease such as diabetic retinopathy, age-related macular degeneration, glaucoma, corneal disease and cataracts, basic research in genetics, and advanced diagnostic techniques such as imaging. Latest areas of interest involve gene editing techniques and the application of stem cell technology in ophthalmology. In China, research and application of stem cells in ophthalmic diseases, intraocular sustained-release drug carrier, and precision medicine research in ophthalmology are emerging areas of funding. In 2012 to 2016, research topics of 168 papers collected by ESI focused on macular degeneration, retinal diseases, glaucoma and other eye diseases. How to quickly promote new drugs and new technological achievements to the clinical application is a problem in the field of ophthalmology. How to change the ophthalmology clinic model, so as to provide patients with convenient and quality service, has become a research topic that needs to be given attention to. Conclusions: Based on the multidimensional analysis of innovation and development in the field of ophthalmology, cross application and integration of ophthalmology and high - tech fields such as advanced imaging technology, stem cell technology, gene editing technology, molecular targeting, and artificial intelligence will provide a strong basis for the enhancement of China's ophthalmology research innovation and international competitiveness. Research efforts for ophthalmic transformation should be strengthened, in order to realize the clinical application of the achievements as soon as possible. (Chin J Ophthalmol, 2018, 54: 452-463).

Preclinical evaluation of a GFRA1 targeted antibody-drug conjugate in breast cancer

Despite recent advances in treatment, breast cancer remains the second-most common cause of cancer death among American women. A greater understanding of the molecular characteristics of breast tumors could ultimately lead to improved tumor-targeted treatment options, particularly for subsets of breast cancer patients with unmet needs. Using an unbiased genomics approach to uncover membrane-localized tumor-associated antigens (TAAs), we have identified glial cell line derived neurotrophic factor (GDNF) family receptor α 1 (GFRA1) as a breast cancer TAA. Immunohistochemistry (IHC) revealed that GFRA1 displays a limited normal tissue expression profile coupled with overexpression in specific breast cancer subsets. The cell surface localization as determined by fluorescence-activated cell sorting (FACS) and the rapid internalization kinetics of GFRA1 makes it an ideal target for therapeutic exploitation as an antibody-drug conjugate (ADC). Here, we describe the development of a pyrrolobenzodiazepine (PBD)-armed, GFRA1-targeted ADC that demonstrates cytotoxicity in GFRA1-positive cell lines and patient-derived xenograft (PDX) models. The safety profile of the rat cross-reactive GFRA1-PBD was assessed in a rat toxicology study to find transient cellularity reductions in the bone marrow and peripheral blood, consistent with known off-target effects of PBD ADC's. These studies reveal no evidence of on-target toxicity and support further evaluation of GFRA1-PBD in GFRA1-positive tumors.

A Feasibility Study of a New Unibody Branched Stent Graft Applied to Reconstruct the Canine Aortic Arch

OBJECTIVES

The aim was to evaluate the feasibility and safety of a new unibody branched stent graft for the reconstruction of the canine aortic arch.

METHODS

The unibody branched stent grafts included single branched stent grafts and double branched stent grafts. The main stent graft and branched limbs were sutured together. The branched stent grafts were folded into the introducer system, which consisted of a double channel catheter, a detachable sleeve, and an introducer sheath. The branched stent grafts were introduced and deployed into the aortic arch by the delivery system. Twenty adult mongrel dogs were used for the experiments. Ten dogs were implanted with single branched stent grafts; the other 10 were implanted with double branched stent grafts. The surviving animals were followed up for 3 months. Computed tomography angiography (CTA) was performed to observe the status of the branched stent grafts.

RESULTS

All the unibody branched stent grafts were successfully implanted into the canine aortic arches. The technical success rate was 100%. There was no cerebral infarction, paraplegia or incision infection. CTA showed that all the branched stent grafts were patent; there was no endoleak or stent migration.

CONCLUSIONS

The unibody branched stent graft system could be used to reconstruct the aortic arch. The animal experimental procedures demonstrated the safety and feasibility of the unibody branched stent graft system.

[Comparison of the prognostic value of the seventh and eighth edition of The AJCC Esophageal Cancer Staging System for the patients with stage Ⅱ and Ⅲesophageal squamous cell carcinoma]

Objective: To compare and evaluate the prognostic value of the 7(th) and 8(th) edition of The AJCC Esophageal Cancer Staging System for patients with stage Ⅱ and Ⅲ esophageal squamous cell carcinoma. Methods: The clinical data of 328 esophageal cancer patients who received operation at Department of Esophageal Cancer, Tianjin Tumour Hospital from January 2006 to December 2010 were restrospectively analyzed. There were 63 female and 265 male patients. The mean age was 65 (range: 33 to 87) years. Univariate and multivariate analysis were performed to identify the prognosis factors. Results: The five years overall survival rates among patients with stage Ⅱ and Ⅲ were both significantly different (χ(2)=87.035, 84.730, all P=0.000) according to the 7(th) and 8(th) editions of the TNM staging systems. The five years overall survival rate among patients with stage ⅡB and ⅢA were significantly different (39.6% vs 23.4%, P=0.001) according to the 7(th) edition of the esophageal cancer staging systems.According to the 8(th) edition of the esophageal cancer staging system, the 5 years survival rate of patients with stage ⅡA and ⅡB, ⅢB and Ⅳ was statistically significant (58.5% vs. 35.5%, P=0.040; 18.9% vs. 0, P=0.000). In multivariate analysis, tumor size, T staging, N staging and tumor differentiation (HR=1.592, 95%CI: 1.185 to 2.139, P=0.002; HR=1.519, 95% CI: 1.236 to 1.867, P=0.000; HR=1.647, 95% CI: 1.448 to 1.874, P=0.000; HR=1.404, 95% CI: 1.059 to 1.861, P=0.018) were the main independent prognosis factors affecting the prognosis of esophageal squamous cell carcinoma patients. Conclusions: Both the 7(th) and the 8(th) editions of TNM staging systems are able to reflect the clinical prognosis of patients receiving radical resection of esophageal cancer, and the factors of tumor size, differentiaton, invasion depth and lymph node metastases are the independent predictors of prognosis. The 8(th) edition provides a more detailed and more reasonable for the staging of stage Ⅱ and Ⅲ for esophageal cancer patients than the 7(th) edition, and it is more accurate for the prognosis of patients with esophageal cancer after surgery.

Dissection of a circulating CD3+ CD20+ T cell subpopulation in patients with psoriasis

CD3⁺ CD20⁺ T cells are a population of CD3⁺ T cells that express CD20 and identified in healthy donors and autoimmune diseases. However, the nature and role of these cells in patients with psoriasis remain unclear. In this study, we aimed to investigate the level, phenotype, functional and clinical relevance of CD3⁺ CD20⁺ T cells in the peripheral blood of patients with psoriasis. We found that a small subset of CD3⁺ T cells expressed CD20 molecule in the peripheral blood of patients with psoriasis, and their levels were similar to those in healthy donors. Circulating CD3⁺ CD20⁺ T cells in patients with psoriasis were enriched in CD4⁺ cells and displayed an activated effector phenotype, as these cells contained fewer CD45RA⁺ -naive and CCR7⁺ cells with increased activity than those of CD3⁺ T cells lacking CD20. In addition, compared with healthy donors, circulating CD3⁺ CD20⁺ T cells in patients with psoriasis produced more cytokines, interleukin (IL)-17A, tumour necrosis factor (TNF)-α and IL-21, but not IL-4 and IFN-γ. Furthermore, a significantly positive correlation was found between the levels of IL-17A, TNF-α and IL-21-production CD3⁺ CD20⁺ T cells with Psoriasis Area and Severity Index scores. Our findings suggest that CD3⁺ CD20⁺ T cells may play a role in the pathogenesis of psoriasis.

Spectacles need and ownership among multiethnic students in rural China

OBJECTIVES

The aim of this study is to describe the prevalence and associated factors of spectacles need and ownership among multiethnic school students in rural China.

STUDY DESIGN

School-based cross-sectional study.

METHODS

This school-based eye study was conducted in Yunnan province located in Southwestern China. Questionnaires were filled out by children with the help of their parents concerning demographic characteristics, spectacles usage, and myopia-related lifestyle exposures. Spectacles need was defined as participants who had an uncorrected visual acuity (VA) of less than 6/12 but could be corrected to more than 6/12 in the better-seeing eye, with myopia of less than -0.5 diopters (D), hyperopia of more than +2.0 D, or astigmatism of more than 0.75 D in both eyes. Definition of spectacles ownership was based on spectacles wearing at school on the examination day.

RESULTS

Among the 7681 students aged 5-16 years participating in this study, 7166 (93.3% of the study participants) successfully completed VA tests and questionnaires. The rate of spectacles need among children with an uncorrected VA of 6/12 or worse in either eye was 68.3% (623/912). Among the students who needed spectacles, only 18.9% owned them. Multivariate analyses revealed that spectacles ownership was significantly associated with increasing age (odds ratio [OR]: 1.30; 95% confidence interval [CI]: 1.08-1.55), more time on reading and writing (OR = 1.66; 95% CI: 1.15-2.40), having myopic friend(s) (OR: 1.90; 95% CI: 1.01-3.56), self-awareness of myopia (OR: 6.67; 95% CI: 2.48-17.92), and poorer uncorrected VA (OR: 4.57; 95% CI: 2.78-7.52).

CONCLUSIONS

We observed a lower rate of spectacles ownership among rural children compared with those of similar ages in urban China. These findings may have important public health implications for China and other countries regarding vision-related health resources allocation.

Note: Development of a multichannel magnetic probe array for magnetohydrodynamic activity studies in Sino-United Spherical Tokamak

A 30-channel movable magnetic probe radial array measuring the poloidal magnetic field's time derivative Ḃ_θ has been developed and installed on the Sino-United Spherical Tokamak to investigate the magnetohydrodynamic (MHD) activities in ohmic discharges. The probe array consists of thirty identical commercial chip inductors mounted on a slim printed circuit board and shielded by a customized quartz tube of 14 mm in outer diameter. With the application of instrumentation amplifiers, the system exhibits a good signal to noise ratio and the measured vertical field spatial distribution agrees well with the simulation result. The measured spatial and temporal distribution of Ḃ_θ during the MHD activities exhibits a clear phase reversal layer, which is a direct proof of tearing mode and provides a reliable indication of the magnetic island chain position.

Soluble TAM receptor tyrosine kinases in rheumatoid arthritis: correlation with disease activity and bone destruction

The TAM receptor tyrosine kinases (TAM RTK) are a subfamily of receptor tyrosine kinases, the role of which in autoimmune diseases such as systemic lupus erythematosus has been well explored, while their functions in rheumatoid arthritis (RA) remain largely unknown. In this study, we investigated the role of soluble TAM receptor tyrosine kinases (sAxl/sMer/sTyro3) in patients with RA. A total of 306 RA patients, 100 osteoarthritis (OA) patients and 120 healthy controls (HCs) were enrolled into this study. The serum concentrations of sAxl/sMer/sTyro3 were measured by enzyme-linked immunosorbent assay (ELISA), then the associations between sAxl/sMer/sTyro3 levels and clinical features of RA patients were analysed. We also investigated whether sTyro3 could promote osteoclast differentiation in vitro in RA patients. The results showed that compared with healthy controls (HCs), sTyro3 levels in the serum of RA patients were elevated remarkably and sMer levels were decreased significantly, whereas there was no difference between HCs and RA patients on sAxl levels. The sTyro3 levels were correlated weakly but positively with white blood cells (WBC), immunoglobulin (Ig)M, rheumatoid factor (RF), swollen joint counts, tender joint counts, total sharp scores and joint erosion scores. Conversely, there were no significant correlations between sMer levels and the above indices. Moreover, RA patients with high disease activity also showed higher sTyro3 levels. In-vitro osteoclast differentiation assay showed further that tartrate-resistant acid phosphatase (TRAP)⁺ osteoclasts were increased significantly in the presence of sTyro3. Collectively, our study indicated that serum sTyro3 levels were elevated in RA patients and correlated positively with disease activity and bone destruction, which may serve as an important participant in RA pathogenesis.

Pyrrolobenzodiazepine Antibody-Drug Conjugates Designed for Stable Thiol Conjugation

Thiosuccinimide-linked antibody-drug conjugates (ADCs) are susceptible to drug loss over time due to a retro-Michael reaction, which can be prevented by selecting stable conjugation positions or hydrolysis of the thiosuccinimide. Here, we investigate pyrrolobenzodiazepine (PBD) ADC drug-linkers equipped with N-phenyl maleimide functionality for stable thiol conjugation via thiosuccinimide hydrolysis. Two PBD drug-linker formats (enzyme-cleavable and non-cleavable) were evaluated following site-specific conjugation to an engineered cysteine incorporated at position T289, which is known to be unstable for N-alkyl maleimide conjugates. N-phenyl maleimide PBDs conjugated to antibodies with similar efficiencies as N-alkyl maleimide PBDs and enhanced thiosuccinimide hydrolysis for N-phenyl maleimide PBDs was confirmed by mass spectrometry, capillary isoelectric focusing, and a SYPRO Orange dye binding assay. All of the PBD ADCs were highly potent in vitro regardless of maleimide- or linker-type, exhibiting low pM EC₅₀ values. Thiol conjugation to N-phenyl maleimide PBD minimized the retro-Michael reaction in both rat and mouse serum. However, cleavage of the valine-alanine dipeptide in mouse serum for ADCs containing cleavable drug-linker led to drug loss regardless of maleimide type, which impacted ADC potency in tumor growth inhibition studies that were conducted in mouse models. Therapeutic improvement in mouse tumor models was realized for ADCs prepared with non-cleavable PBD drug-linkers that were conjugated through N-phenyl maleimide, where a stronger tumor growth inhibition (TGI) response was achieved when compared to the analogous N-alkyl maleimide drug-linker ADC. Altogether, our findings highlight the stability and efficacy benefits of N-phenyl maleimide functionality for ADCs that are produced with thiol-maleimide conjugation chemistry.

Insertion of scFv into the hinge domain of full-length IgG1 monoclonal antibody results in tetravalent bispecific molecule with robust properties

By simultaneous binding two disease mediators, bispecific antibodies offer the opportunity to broaden the utility of antibody-based therapies. Herein, we describe the design and characterization of Bs4Ab, an innovative and generic bispecific tetravalent antibody platform. The Bs4Ab format comprises a full-length IgG1 monoclonal antibody with a scFv inserted into the hinge domain. The Bs4Ab design demonstrates robust manufacturability as evidenced by MEDI3902, which is currently in clinical development. To further demonstrate the applicability of the Bs4Ab technology, we describe the molecular engineering, biochemical, biophysical, and in vivo characterization of a bispecific tetravalent Bs4Ab that, by simultaneously binding vascular endothelial growth factor and angiopoietin-2, inhibits their function. We also demonstrate that the Bs4Ab platform allows Fc-engineering similar to that achieved with IgG1 antibodies, such as mutations to extend half-life or modulate effector functions.

[Interaction between TRPC1 and STIM1 in calcium sensing receptor mediated calcium influx and nitric oxide production in human umbilical vein endothelial cells]

Objective: To investigate the interaction of Ca(2+) protein TRPC1 and STIM1 in extracellular Ca(2+) -sensing receptor (CaR)-induced extracellular Ca(2+) influx and the production of nitric oxide (NO). Methods: Human umbilical vein endothelial cells (HUVECs) were cultured and incubated with CaR agonist spermine (activating store-operates cation channels (SOC) and receptor-operated channels (ROC)), CaR negative allosteric modulator Calhex231 (blocking SOC, activating ROC) and ROC analogue TPA (activating ROC, blocking SOC), protein kinase C (PKC) inhibitor Ro31-8220, PKCs and PKCμ inhibitor Go6967(activate SOC, blocking ROC), respectively. The interaction of TRPC1 and STIM1 was determined using the immunofluorescence methods. The interaction between TRPC1 and STIM1 were examined by Co-immuno precipitation. The HUVECs were divided into: TRPC1 and STIM1 short hairpin RNA group (shTRPC1+ shSTIM1 group), vehicle-TRPC1+ vehicle-STIM1 group and control group. The cells were incubated with four different treatments under the action of above mentioned interventions, intracellular Ca(2+) concentration ([Ca(2+) ](i)) was detected using the fluorescence Ca(2+) indicator Fura-2/AM, the production of NO was determined by DAF-FM. Results: (1) The expression of TRPC1 and STIM1 proteins levels in HUVECs: Under the confocal microscope, TRPC1 and STIM1 protein expression showed masculine gender, both located in cytoplasm in the normal control group. Post incubation with Calhex231+ TPA, Ro31-8220 and Go6967, TRPC1 and STIM1 positioned in cytoplasm was significantly reduced, and the combined TRPC1 and STIM1 was also significantly reduced. (2) The interaction of TRPC1 and STIM1 in HUVECs: The relative ratios of Calhex231+ TPA+ Spermine+ Ca(2+) group, Ro31-8220+ Spermine+ Ca(2+) group and Go6976+ Spermine+ Ca(2+) group STIM1/TRPC1 and TRPC1/STIM1 were as follows: (25.98±2.17)% and (44.10±4.01)%, (20.85±1.01)% and (46.31±3.47)%, (23.88±2.05)% and (39.65±2.91)%, which were significantly lower than those in the control group (100.00±4.66)% and (100.00±6.40)% and in the Spermine+ Ca(2+) group (106.04±2.45)% and (107.78±2.66)% (all P<0.05). (3) The influence of joint TRPC1 and STIM1 transfection to four different drugs treated HUVECs on [Ca(2+) ](i) and NO generation: The changes of two excitation fluorescence intensity ratio and NO net fluorescence intensity values were consistent, [Ca(2+) ](i) and NO net fluorescence intensity values were significantly lower in the experimental group than the control group and the vehicle group (all P<0.05), while which were similar between the vehicle group and control group (all P>0.05). Conclusions: Our results indicate that TRPC1 and STIM1 jointly regulate CaR-mediated Ca(2+) influx and nitric oxide generation in HUVECs in the form of binary complex.

Determination of eddy current response with magnetic measurements

Accurate mutual inductances between magnetic diagnostics and poloidal field coils are an essential requirement for determining the poloidal flux for plasma equilibrium reconstruction. The mutual inductance calibration of the flux loops and magnetic probes requires time-varying coil currents, which also simultaneously drive eddy currents in electrically conducting structures. The eddy current-induced field appearing in the magnetic measurements can substantially increase the calibration error in the model if the eddy currents are neglected. In this paper, an expression of the magnetic diagnostic response to the coil currents is used to calibrate the mutual inductances, estimate the conductor time constant, and predict the eddy currents response. It is found that the eddy current effects in magnetic signals can be well-explained by the eddy current response determination. A set of experiments using a specially shaped saddle coil diagnostic are conducted to measure the SUNIST-like eddy current response and to examine the accuracy of this method. In shots that include plasmas, this approach can more accurately determine the plasma-related response in the magnetic signals by eliminating the field due to the eddy currents produced by the external field.

Abstract 76: Synthetic lethal targeting of BRCA mutant tumors with antibody linked pyrrolobenzodiazepine dimers

Pyrrolbenzodiazepine dimers (PBDs) are amongst the most potent DNA alkylating agents, with activity against a broad spectrum of tumors. PBDs form cross-links within the minor groove of DNA causing double strand breaks (DSB). DNA repair genes such as BRCA1 and BRCA2 play important roles in homologous recombination repair (HRR) of DSB. Cells defective in BRCA1 or BRCA2 are known to be sensitive to DNA interstrand crosslinks. Accordingly, it is possible that PBD-based ADCs will have enhanced killing of cells (synthetic lethality) in which HR processes are defective by inactivation of BRCA1 or BRCA2 genes in breast, ovarian and other cancers. To determine anti-tumor activity of PBD dimers, we have used MEDI0641, PBD-dimer conjugated to anti-5T4 antibody, against BRCA wild type and mutant xenograft tumor models. MEDI0641 was &gt;3-fold more potent in BRCA1 or BRCA2 mutant models than in wild-type xenografts. Similar observations were seen in 25 patient-derived xenograft (PDX) models (19 breast and 6 ovarian) bearing mutations in BRCA1 or BRCA2 (blinded to 5T4 expression) treated with MEDI0641. Out of a total of 25 PDX models, 17 models had tumor regression with a single administration of MEDI0641 at 0.3 mg/kg (response rate = 68%), and 14 models showed response to 0.1 mg/kg of MEDI0641 (response rate = 56%). In BRCA wild-type PDX models, a higher dose of 1 mg/kg was required to achieve full anti-tumor efficacy. Retrospective analysis of 5T4 expression in PDX tumors demonstrated no correlation between efficacy and target expression in BRCA mutant PDX models. To further delineate the role of BRCA1/2 mutations in determining sensitivity to PBD, we used siRNA knock-down of both BRCA1 and BRCA2 in the DNA repair wild type HeLa cells. Knockdown of BRCA genes sensitized Hela cells to PBD payload and MEDI0641 in vitro. Anti-tumor activity of MEDI0641 was further examined in isogenic BRCA2 knockout xenograft models. Genetic deletion of BRCA2 markedly increased anti-tumor activity of MEDI0641. In conclusion, PBD based ADCs may have improved therapeutic window in cancer patients with somatic BRCA mutations.

Citation Format: Haihong Zhong, Ravinder Tammali, Cui Chen, Christine Fazenbaker, Kennedy Maureen, Noel Monks, Jay Harper, Ronald Herbst, Dave Tice. Synthetic lethal targeting of BRCA mutant tumors with antibody linked pyrrolobenzodiazepine dimers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 76. doi:10.1158/1538-7445.AM2017-76

Fractionated Dosing Improves Preclinical Therapeutic Index of Pyrrolobenzodiazepine-Containing Antibody Drug Conjugates

Purpose: To use preclinical models to identify a dosing schedule that improves tolerability of highly potent pyrrolobenzodiazepine dimers (PBDs) antibody drug conjugates (ADCs) without compromising antitumor activity.Experimental Design: A series of dose-fractionation studies were conducted to investigate the pharmacokinetic drivers of safety and efficacy of PBD ADCs in animal models. The exposure-activity relationship was investigated in mouse xenograft models of human prostate cancer, breast cancer, and gastric cancer by comparing antitumor activity after single and fractionated dosing with tumor-targeting ADCs conjugated to SG3249, a potent PBD dimer. The exposure-tolerability relationship was similarly investigated in rat and monkey toxicology studies by comparing tolerability, as assessed by survival, body weight, and organ-specific toxicities, after single and fractionated dosing with ADCs conjugated to SG3249 (rats) or SG3400, a structurally related PBD (monkeys).Results: Observations of similar antitumor activity in mice treated with single or fractionated dosing suggests that antitumor activity of PBD ADCs is more closely related to total exposure (AUC) than peak drug concentrations (C_max). In contrast, improved survival and reduced toxicity in rats and monkeys treated with a fractionated dosing schedule suggests that tolerability of PBD ADCs is more closely associated with C_max than AUC.Conclusions: We provide the first evidence that fractionated dosing can improve preclinical tolerability of at least some PBD ADCs without compromising efficacy. These findings suggest that preclinical exploration of dosing schedule could be an important clinical strategy to improve the therapeutic window of highly potent ADCs and should be investigated further. Clin Cancer Res; 23(19); 5858-68. ©2017 AACR.

Preclinical Evaluation of MEDI0641, a Pyrrolobenzodiazepine-Conjugated Antibody-Drug Conjugate Targeting 5T4

Antibody-drug conjugates (ADC) are used to selectively deliver cytotoxic agents to tumors and have the potential for increased clinical benefit to cancer patients. 5T4 is an oncofetal antigen overexpressed on the cell surface in many carcinomas on both bulk tumor cells as well as cancer stem cells (CSC), has very limited normal tissue expression, and can internalize when bound by an antibody. An anti-5T4 antibody was identified and optimized for efficient binding and internalization in a target-specific manner, and engineered cysteines were incorporated into the molecule for site-specific conjugation. ADCs targeting 5T4 were constructed by site-specifically conjugating the antibody with payloads that possess different mechanisms of action, either a DNA cross-linking pyrrolobenzodiazepine (PBD) dimer or a microtubule-destabilizing tubulysin, so that each ADC had a drug:antibody ratio of 2. The resulting ADCs demonstrated significant target-dependent activity in vitro and in vivo; however, the ADC conjugated with a PBD payload (5T4-PBD) elicited more durable antitumor responses in vivo than the tubulysin conjugate in xenograft models. Likewise, the 5T4-PBD more potently inhibited the growth of 5T4-positive CSCs in vivo, which likely contributed to its superior antitumor activity. Given that the 5T4-PBD possessed both potent antitumor activity as well as anti-CSC activity, and thus could potentially target bulk tumor cells and CSCs in target-positive indications, it was further evaluated in non-GLP rat toxicology studies that demonstrated excellent in vivo stability with an acceptable safety profile. Taken together, these preclinical data support further development of 5T4-PBD, also known as MEDI0641, against 5T4⁺ cancer indications. Mol Cancer Ther; 16(8); 1576-87. ©2017 AACR.

Effect of photoperiod on serum hormone concentrations during the annual reproductive cycle in geese

The poor egg-laying rate of geese hinders the development of the goose industry; therefore, the reproductive performance of geese is an important area of investigation. To evaluate the relationship between photoperiod, reproductive hormones, and reproductive activity during the egg-laying cycle in geese under natural conditions, we collected blood samples from Sichuan white geese and Xupu geese to quantify changes in prolactin (PRL), estradiol (E2), vasoactive intestinal polypeptide (VIP), follicle stimulating hormone (FSH), gonadotropin-inhibitory hormone (GnIH), and luteinizing hormone (LH). We also calculated the rate of egg laying for the two populations during the egg-laying cycle. We show that the egg-laying rate and the serum concentration of some hormones (PRL, E2, VIP, FSH, GnIH, and LH) differed significantly between the two populations during the pre-laying, laying, and ceased-laying periods. Serum LH concentrations may be associated with maturation of the ovary and oviducts, whereas FSH, PRL, and GnIH play important roles in egg laying. These results provide a useful resource for future studies examining the laying rate in geese.

Efficient Preparation of Site-Specific Antibody-Drug Conjugates Using Cysteine Insertion

Antibody-drug conjugates (ADCs) are a class of biopharmaceuticals that combine the specificity of antibodies with the high-potency of cytotoxic drugs. Engineering cysteine residues in the antibodies using mutagenesis is a common method to prepare site-specific ADCs. With this approach, solvent accessible amino acids in the antibody have been selected for substitution with cysteine for conjugating maleimide-bearing cytotoxic drugs, resulting in homogeneous and stable site-specific ADCs. Here we describe a cysteine engineering approach based on the insertion of cysteines before and after selected sites in the antibody, which can be used for site-specific preparation of ADCs. Cysteine-inserted antibodies have expression level and monomeric content similar to the native antibodies. Conjugation to a pyrrolobenzodiazepine dimer (SG3249) resulted in comparable efficiency of site-specific conjugation between cysteine-inserted and cysteine-substituted antibodies. Cysteine-inserted ADCs were shown to have biophysical properties, FcRn, and antigen binding affinity similar to the cysteine-substituted ADCs. These ADCs were comparable for serum stability to the ADCs prepared using cysteine-mutagenesis and had selective and potent cytotoxicity against human prostate cancer cells. Two of the cysteine-inserted variants abolish binding of the resulting ADCs to FcγRs in vitro, thereby potentially preventing non-target mediated uptake of the ADCs by cells of the innate immune system that express FcγRs, which may result in mitigating off-target toxicities. A selected cysteine-inserted ADC demonstrated potent dose-dependent anti-tumor activity in a xenograph tumor mouse model of human breast adenocarcinoma expressing the oncofetal antigen 5T4.

A millikelvin all-fiber cavity optomechanical apparatus for merging with ultra-cold atoms in a hybrid quantum system

We describe the construction of an apparatus designed to realize a hybrid quantum system comprised of a cryogenically cooled mechanical oscillator and ultra-cold ⁸⁷Rb atoms coupled via light. The outstanding feature of our instrument is an in situ adjustable asymmetric all-fiber membrane-in-the-middle cavity located inside an ultra-high vacuum dilution refrigerator based cryostat. We show that Bose-Einstein condensates of N=2×10⁶ atoms can be produced in less than 20 s and demonstrate a single photon optomechanical coupling strength of g₀=2π×9 kHz employing a high-stress Si₃N₄ membrane with a mechanical quality factor Q_m>10⁷ at a cavity setup temperature of T_MiM = 480 mK.

Electrocatalytic Cobalt Nanoparticles Interacting with Nitrogen-Doped Carbon Nanotube in Situ Generated from a Metal-Organic Framework for the Oxygen Reduction Reaction

A metal organic framework (MOF), synthesized from cobalt salt, melamine (mela), and 1,4-dicarboxybezene (BDC), was used as precursor to prepare Co/CoN_x/N-CNT/C electrocatalyst via heat treatment at different temperature (700-900 °C) under nitrogen atmosphere. Crystallites size and microstrain in the 800 °C heat-treated sample (MOFs-800) were the lowest, whereas the stacking fault value was the highest among the rest of the homemade samples, as attested to by the Williamson-Hall analysis, hence assessing that the structural or/and surface modification of Co nanoparticles (NPs), found in MOFs-800, was different from that in other samples. CNTs in MOFs-800, interacting with Co NPs, were formed on the surface of the support, keeping the hexagonal shape of the initial MOF. Among the three homemade samples, the MOF-800 sample, with the best electrocatalytic performance toward oxygen reduction reaction (ORR) in 0.1 M KOH solution, showed the highest density of CNTs skin on the support, the lowest I_D/I_G ratio, and the largest N atomic content in form of pyridinic-N, CoN_x, pyrrolic-N, graphitic-N, and oxidized-N species. Based on the binding energy shift toward lower energies, a strong interaction between the active site and the support was identified for MOFs-800 sample. The number of electron transfer was 3.8 on MOFs-800, close to the value of 4.0 determined on the Pt/C benchmark, thus implying a fast and efficient multielectron reduction of molecular oxygen on CoN_x active sites. In addition, the chronoamperometric response within 24 000 s showed a more stable current density at 0.69 V/RHE on MOFs-800 as compared with that of Pt/C.

Effects of feeding conditions on gene expression in chicken breast muscle

Chicken meat quality is becoming increasingly important among breeders and consumers. To understand the effect of feeding conditions on chicken meat quality, we investigated the profiles of genes expressed in chicken breast muscle. Using RNA sequencing, we identified 336, 321, and 387 differentially expressed genes among Chengkou, Daninghe, and Qingjiaoma chickens under scatter- and captivity-feeding conditions. Twenty-two genes differentially expressed between different feeding conditions were shown to be common among the three breeds. Seven of these genes were assessed by real-time quantitative PCR, which confirmed the findings of RNA sequencing and suggested that the results were viable. The differentially expressed genes showed enrichment for a series of significant pathways, including energy metabolism, xenobiotics biodegradation and metabolism, and the immune system. These results provide a solid foundation for elucidating the molecular mechanisms underlying chicken meat quality.

Remodeling of the gut microbiota and structural shifts in Preeclampsia patients in South China

Preeclampsia (PE) is one of the pregnancy metabolic diseases. Since Gut microbiota play important roles in the hosts' metabolism, it is necessary to investigate the gut microbiota in PE patients, so that some intestinal dysbiosis might be detected as a biomarker for PE early diagnosis or as a target for intervention. One hundred subjects were categorized into four groups: 26 PE patients in late pregnancy, healthy individuals in early, middle, and late pregnancy (26/24/24 women). Gut microbiota were analyzed by sequencing the V4 region of the 16S rDNA gene using Illuminal MiSeq. Data were analyzed by multivariate statistics. Bacteroidetes was the dominant bacterium (47.57-52.35%) in the pregnant women in South China. Tenericutes increased while Verrucomicrobia almost disappeared in late pregnancy. In the PE patients, there was an overall increase in pathogenic bacteria, Clostridium perfringens (p = 0.03) and Bulleidia moorei (p = 0.00) but a reduction in probiotic bacteria Coprococcus catus (p = 0.03). Our research suggests that there is a significant structural shift of the gut microbiota in PE patients, which might be associated with the occurrence and development of the disease. However, further studies are required to understand the underlying mechanisms.